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Theoretical studies on vibrational spectra of some mixed carbonyl-halide complexes of Osmium(II)
Spectrochimica Acta Part A 65 (2006) 501–510
Theoretical studies on vibrational spectra of some mixed carbonyl-halide complexes of Osmium(II) Jianying Zhao a , Yu Zhang a,∗ , Guodong Tang a , Longgen Zhu b a
Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials, Department of Chemistry, Huaiyin Teachers College, Huai’an 223001, Jiangsu, PR China b State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093, Jiangsu, PR China Received 5 February 2005; received in revised form 30 May 2005; accepted 3 December 2005
Abstract The vibrational spectra of Os(CO)6 2+ and some of its mixed carbonyl-halide complexes, cis-Os(CO)2 X4 2− , fac-Os(CO)3 X3 − and Os(CO)5 X+ (X = F, Cl, Br and I), have been systematically investigated by ab initio RHF and density functional B3LYP methods with LanL2DZ and SDD basis sets. The calculated vibrational frequencies of complexes Os(CO)6 2+ , cis-Os(CO)2 X4 2− and fac-Os(CO)3 X3 − are evaluated via comparison with the experimental values. In infrared frequency region, the C–O stretching vibrational frequencies calculated at B3LYP level with two basis sets are in good agreement with the observed values with deviations less than 5%. In the far-infrared region, the B3LYP/SDD method achieved the best results with deviations less than 9% for Os–X stretching and less than 8% for Os–C stretching vibrational frequencies. The vibrational frequencies for Os(CO)5 X+ that have not been experimentally reported were predicted. © 2005 Elsevier B.V. All rights reserved. Keywords: Vibrational frequencies; Ab initio RHF; Density functional B3LYP; Mixed carbonyl-halide complexes of Os(II)
1. Introduction Since the first transition-metal carbonyl complex, nickel tetracarbonyl, was synthesized by Mond et al. [1]. These type of complexes have become one of the most important classes of inorganic compounds. These complexes are not just of interest in academic research [2–6], they are also used by industry as important homogeneous and heterogeneous catalysts [7–14]. In these complexes, the nature of the bonds between transition metals and carbon monoxides were well established. The synergic bonding model due to Dewar [15] and Chatt and Duncanson [16] has a central role in organometallic chemistry. The power of this model has been demonstrated by Hoffmann and co-workers, who showed that the structure and reactivity of many transitionmetal complexes can be understood and, to a certain extent, can even be predicted using the -donation -back-donation picture in conjunction with semiempirical calculations [17–21]. Frenking et al. [22–26] have extensively studied the structures
∗
Corresponding author. Tel.: +86 5173511083; fax: +86 5173942349. E-mail address: [email protected] (Z. Yu).
1386-1425/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.saa.2005.12.001
and bonding of these type complexes, especially OC → M -donation and metal → CO -back-donation. Vibrational spectra is a very important analytical tool to experimentally investigate these kind of transition metal complex, the bond properties can be reflected from vibrational frequencies, vibrational intensities and vibrational force constance, so, the vibrational properties of many transition metal complexes were studied using quantum chemistry methods, such as ab initio Hartree–Fock (HF), Møllar–Plesset (MP2) and density functional theory (DFT) [27–40]. Andrews has reviewed the investigations on the spectroscopic and theoretical of vibrational frequencies in transition metal carbonyl cations, neutrals, and anions recently [41]. Some of the vibrational frequencies of mixed carbonyl-halide complexes of Os(II) were experimentally investigated by Cleare and Griffith [42], therefore, we can use theoretical methods with different basis sets to carry out systematic calculations for their vibrational frequencies and compare them with the experimental values. The purposes for this work are to gain further insight into the effect of theoretical methods with different basis sets used on calculations of structure parameters and vibrational frequencies for mixed carbonyl-halide complexes of Os(II), in order to iden-
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tify the preferred computational approach and to establish the level of accuracy that can be reached, and to predict vibrational frequencies for the complexes, in which experimental assignments were uncertain and experimental data were absent.
2. Calculations The geometries of the molecules have been optimized with Oh , C2v , C3v , and C4v symmetries for Os(CO)6 2+ , cis-
Table 1 Optimized bond lengths of Os(CO)6 2+ and cis-Os(CO)2 X4 2− Os(CO)6 2+
Os(CO)2 F4 2−
Os(CO)2 Cl4 2−
Os(CO)2 Br4 2−
Os(CO)2 I4 2−
1.878 1.166 2.063 2.087
1.904 1.152 2.573 2.574
1.911 1.150 2.732 2.744
1.916 1.149 2.904 2.933
2.097 1.117 – –
1.883 1.164 2.073 2.090
1.909 1.151 2.575 2.578
1.916 1.148 2.714 2.728
1.920 1.147 2.904 2.938
ROs–C RC–O ROs−X1 ROs−X3
2.037 1.150 – –
1.846 1.212 2.051 2.067
1.850 1.198 2.546 2.556
1.854 1.196 2.706 2.729
1.859 1.195 2.878 2.920
ROs–C RC–O ROs−X1 ROs−X3
2.044 1.150 – –
1.851 1.211 2.063 2.069
1.855 1.197 2.538 2.554
1.859 1.194 2.684 2.712
1.864 1.193 2.874 2.919
Method
Bond
RHF/LanL2DZ
ROs–C RC–O ROs−X1 ROs−X3
RHF/SDD
ROs–C RC–O ROs−X1 ROs−X3
B3LYP/LanL2DZ
B3LYP/SDD
– – – –
Table 2 Optimized bond lengths of fac-Os(CO)3 X3 − Method
Bond lengths
Os(CO)3 F3 −
Os(CO)3 Cl3 −
Os(CO)3 Br3 −
Os(CO)3 I3 −
RHF/LanL2DZ
Os–X Os–C C–O
2.036 1.943 1.144
2.526 1.947 1.140
2.685 1.949 1.140
2.863 1.949 1.141
RHF/SDD
Os–X Os–C C–O
2.044 1.949 1.143
2.529 1.950 1.139
2.668 1.952 1.139
2.870 1.953 1.140
B3LYP/LanL2DZ
Os–X Os–C C–O
2.024 1.900 1.183
2.518 1.898 1.179
2.683 1.900 1.179
2.867 1.902 1.180
B3LYP/SDD
Os–X Os–C C–O
2.032 1.908 1.183
2.514 1.904 1.179
2.663 1.906 1.179
2.866 1.908 1.179
Table 3 Optimized bond lengths of Os(CO)5 X+ Method
Bond
Os(CO)5 F+
Os(CO)5 Cl+
Os(CO)5 Br+
Os(CO)5 I+
RHF/LanL2DZ
ROs–C RC–O ROs–X
2.062, 2.018 1.121, 1.127 2.011
2.055, 2.012 1.121, 1.126 2.467
2.052, 2.014 1.122, 1.126 2.622
2.048, 2.017 1.123, 1.126 2.799
RHF/SDD
ROs–C RC–O ROs–X
2.071, 2.022 1.122, 1.127 2.013
2.065, 2.013 1.122, 1.126 2.468
2.062, 2.018 1.123, 1.127 2.601
2.058, 2.021 1.123, 1.127 2.802
B3LYP/LanL2DZ
ROs–C RC–O ROs–X
2.009, 1.963 1.154, 1.163 2.037
2.006, 1.957 1.155, 1.162 2.492
2.004, 1.959 1.156, 1.162 2.650
2.001, 1.963 1.157, 1.162 2.827
B3LYP/SDD
ROs–C RC–O ROs–X
2.018, 1.966 1.155, 1.164 2.037
2.015, 1.961 1.155, 1.163 2.490
2.013, 1.965 1.156, 1.163 2.628
2.010, 1.968 1.157, 1.163 2.825
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503
Fig. 1. Optimized geometries of: (a) Os(CO)6 2+ ; (b) cis-Os(CO)2 X4 2− ; (c) fac-Os(CO)3 X3 − ; (d) Os(CO)5 X+ .
Os(CO)2 X4 2− , fac-Os(CO)3 X3 − and Os(CO)5 X+ (X = F, Cl, Br and I), respectively. These geometry optimization procedures proceed in two steps—firstly the geometries were constructed by MM+ molecular dynamics from HyperChem 6.0 package
[43], and secondly, optimized by RHF and DFT levels of theory with LanL2DZ (Los Alamos ECP plus double-zeta) [44,45] and SDD (Stuttgart/Dresden effective core potential) [46] basis sets using Gaussian 98W program package [47]. DFT calculations
Table 4 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of Os(CO)6 2+ Assignment
A1g 1 [CO] A1g 2 [OsC] Eg 3 [CO] Eg 4 [OsC] T1g 5 [␦OsCO] T1u 6 [CO] T1u 7 [␦OsCO] T1u 8 [OsC] T1u 9 [␦COsC] T2g 10 [␦OsCO] T2g 11 [␦COsC] T2u 12 [␦OsCO] T2u 13 [␦COsC] a
RHF
B3LYP
Exp.[51]
LanL2DZ
SDD
LanL2DZ
SDD
–
– – – – – – – – – – – – –
2462 (220)a 360 (9) 2429 (173) 355 (0.9) 358 2417 (627) 574 (110) 311 (11) 118 (0.1) 499 (5) 105 (5) 525 90
2211 (222) 427 (13) 2159 (280) 397 (0.04) 359 2138 (599) 578 (90) 348 (42) 116 (0.1) 488 (2) 104 (8) 522 86
2204 (227) 423 (14) 2155 (282) 397 (0.02) 350 2132 (590) 572 (91) 339 (37) 113 (0.02) 482 (1) 102 (8) 515 83
2259 – 2218 – – 2190 562 346 – – 132 – –
Data in the parentheses are vibrational intensities.
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Table 5 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of cis–Os(CO)2 X4 2− Method
Assignment
Os(CO)2 F4 2−
Os(CO)2 Cl4 2−
Os(CO)2 Br4 2−
Os(CO)2 I4 2−
RHF/LanL2DZ
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] A1 6 [␦XOsX ] A1 7 [␦COsC ] A1 8 [␦XOsX ] A2 9 [␦OsCO ] A2 10 [␦XOsX ] A2 11 [␦COsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B1 14 [␦COsX ] B1 15 [␦COsX ] B2 16 [CO ] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ] B2 21 [␦COsX ]
2098 (879, 94)a 726 (30, 1) 538 (15, 9) 493 (148, 4) 457 (7, 2) 218 (8, 1) 186 (2, 0.2) 112 (0.5,5) 630 (0.3) 201 (0.3) 105 (2) 654 (39, 0.1) 456 (191, 0.01) 212 (9, 0.6) 119 (5, 1) 1967 (2599, 72) 590 (31, 1) 516 (94, 3) 450 (45, 0.3) 200(3, 1) 123 (3, 0.4)
2166 (1007, 276) 685 (68, 4) 495 (4, 4) 277 (38, 4) 254 (9, 4) 129 (3, 0.5) 114 (1, 5) 97 (1, 0.3) 591 (0.1) 116 (4) 94 (2) 607 (52, 0.3) 268 (98, 0.1) 128 (2, 1) 106 (0.1, 4) 2084 (1746, 94) 548 (22, 0.2) 474 (45, 0.7) 246 (36, 0.4) 125 (4, 1) 90 (0.01, 0.2)
2173 (1081, 399) 671 (80, 9) 489 (5, 7) 182 (17, 3) 154 (2, 4) 121 (0.04, 3) 82 (0.2, 2) 61 (0.2, 0.7) 581 (0.5) 93 (3) 71 (2) 596 (47, 0.4) 186 (53, 0.04) 110 (0.1, 0.7) 78 (0.1, 4) 2102 (1509, 87) 537 (21, 0.4) 468 (29, 1) 156 (18, 1) 99 (0.1, 0.8) 69 (0.03, 0.1)
2170 (1184, 591) 662 (92, 19) 486 (6, 14) 146 (8, 2) 119 (1, 4) 110 (1, 5) 65 (0.1, 1) 46 (0.1, 1) 576 (2) 97 (2) 55 (3) 593 (46, 1) 152 (39, 0.1) 111 (0.7, 1) 61 (0.6, 5) 2109 (1321, 73) 531 (21, 1) 465 (19, 2) 118 (12, 1) 93 (0.3, 0.7) 58 (0.03, 0.1)
RHF/SDD
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] A1 6 [␦XOsX ] A1 7 [␦COsC ] A1 8 [␦XOsX ] A2 9 [␦OsCO ] A2 10 [␦XOsX ] A2 11 [␦COsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B1 14 [␦COsX ] B1 15 [␦COsX ] B2 16 [CO ] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ] B2 21 [␦COsX ]
2103 (897, 98) 719 (28, 0.3) 529 (167, 8) 489 (143, 4) 455 (11, 1) 215 (8, 2) 186 (1, 0.3) 109 (0.5, 5) 619 (0.3) 201 (0.4) 103 (2) 644 (37, 0.01) 452 (210, 0.1) 212 (8, 0.6) 117 (6, 1) 1976 (2529, 81) 578 (29, 1) 500 (119, 2) 445 (32, 0.05) 204 (3, 1) 124 (3, 0.3)
2169 (956, 225) 678 (63, 3) 485 (3, 5) 272 (35, 4) 246 (10, 2) 130 (1, 0.6) 113 (0.4, 4) 98 (1, 0.1) 583 (0.02) 118 (3) 95 (1) 601 (50, 0.1) 259 (95, 0.1) 128 (3, 1) 107 (0.1, 4) 2091 (1611, 88) 539 (22, 0.4) 461 (45, 0.5) 238 (37, 0.1) 127 (3, 1) 93 (0.01, 0.2)
2179 (1023, 192) 666 (70, 6) 477 (4, 7) 180 (20, 4) 148 (4, 5) 119 (0.1, 2) 83 (0.2, 1) 62 (0.2, 0.8) 573 (0.3) 96 (3) 72 (1) 590 (41, 0.3) 177 (67, 0.4) 111 (0.1, 0.7) 78 (0.2, 3) 2114 (1325, 80) 528 (17, 0.6) 455 (25, 0.6) 149 (24, 1) 102 (0.1, 1) 71 (0.02, 0.1)
2179 (1057, 225) 655 (83, 11) 475 (4, 12) 144 (9, 3) 118 (1, 5) 107 (2, 6) 66 (0.6, 1) 47 (0.01, 1) 567 (1) 99 (2) 55 (2) 584 (46, 0.4) 147 (42, 1) 111 (2, 1) 62 (0.6, 3) 2124 (1084, 53) 522 (17, 1) 452 (14, 1) 114 (14, 3) 94 (1, 0.2) 58 (0.04, 0.2)
B3LYP/LanL2DZ
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] A1 6 [␦XOsX ] A1 7 [␦COsC ] A1 8 [␦XOsX ] A2 9 [␦OsCO ] A2 10 [␦XOsX ] A2 11 [␦COsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B1 14 [␦COsX ] B1 15 [␦COsX ] B2 16 [CO ] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ] B2 21 [␦COsX ]
1892 (545, 30) 676 (8, 0.5) 574 (15, 30) 494 (102, 12) 453 (20, 6) 225 (3, 1) 191 (0.8, 0.5) 105 (1, 6) 594 (1) 203 (1) 101 (3) 624 (9, 0.1) 463 (152, 0.2) 217 (3, 2) 114 (8, 2) 1795 (1446, 16) 570 (2, 15) 548 (20, 2) 444 (59, 1) 207 (3, 0.5) 114 (3, 0.4)
1940 (709, 114) 650 (36, 2) 573 (6, 29) 278 (18, 19) 255 (14, 12) 129 (1, 0.4) 107 (0.01, 8) 99 (0.1, 0.4) 570 (0.2) 117 (7) 85 (3) 595 (24, 0.2) 277 (78, 0.04) 125 (0.1, 4) 100 (1, 5) 1859 (1191, 27) 561 (1, 18) 516 (16, 0.5) 243 (32, 1) 125 (1, 0.6) 79 (0.3, 0.3)
1943 (759, 160) 635 (49, 5) 570 (6, 29) 180 (8, 4) 154 (3, 15) 112 (0.005, 4.2) 81 (0.1, 3) 60 (0.009, 1) 558 (0.05) 85 (7) 69 (1) 581 (25, 0.02) 190 (41, 0.003) 98 (0.1, 1) 76 (0.4, 7) 1868 (1054, 30) 556 (0.5, 17) 504 (15, 1) 153 (14, 2) 92 (0.03, 0.6) 61 (0.1, 0.2)
1942 (803, 217) 622 (63, 121) 566 (7, 29) 141 (4, 5) 113 (0.5, 17) 108 (0.6, 7) 74 (0.5, 3) 44 (0.001, 2) 548 (0.01) 85 (5) 53 (4) 574 (26, 0.01) 153 (28, 0.04) 98 (0.003, 2) 60 (1, 7) 1872 (920, 32) 550 (0.1, 16) 496 (15, 2) 116 (8, 3) 83 (0.6, 0.6) 52 (0.3, 0.3)
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Table 5 (Continued ) Method
Assignment
Os(CO)2 F4 2−
Os(CO)2 Cl4 2−
Os(CO)2 Br4 2−
Os(CO)2 I4 2−
B3LYP/SDD
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] A1 6 [␦XOsX ] A1 7 [␦COsC ] A1 8 [␦XOsX ] A2 9 [␦OsCO ] A2 10 [␦XOsX ] A2 11 [␦COsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B1 14 [␦COsX ] B1 15 [␦COsX ] B2 16 [CO ] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ] B2 21 [␦COsX ]
1897 (566, 22) 670 (7, 0.2) 565 (13, 27) 496 (98, 13) 457 (30, 4) 222 (3, 1) 191 (0.6, 0.5) 102 (1, 6) 585 (1) 202 (1) 96 (3) 616 (9, 0.2) 466 (178, 0.01) 215 (3, 1) 111 (8, 2) 1799 (1440, 18) 559 (6, 14) 538 (20, 1) 445 (62, 0.3) 210 (3, 0.5) 116 (3, 0.4)
1941 (680, 71) 645 (33, 0.8) 562 (5, 28) 275 (16, 15) 251 (14, 10) 130 (1, 0.4) 107 (0.1, 7) 100 (0.03, 0.2) 562 (0.5) 120 (4) 85 (3) 588 (24, 0.4) 273 (75, 0.02) 128 (0.5, 2) 100 (1, 5) 1860 (1133, 27) 549 (3, 16) 509 (16, 0.7) 240 (31, 0.5) 128 (1, 1) 83 (0.3, 0.3)
1946 (745, 34) 631 (43, 3) 557 (5, 27) 178 (10, 10) 151 (5, 21) 110 (0.004, 4) 84 (0.05, 2) 62 (0.02, 2) 550 (0.2) 86 (7) 71 (1) 574 (21, 0.2) 183 (54, 0.4) 99(0.1, 1) 80(0.4, 6) 1871 (950, 35) 542 (1, 11) 496 (12, 1) 148 (20, 4) 95 (0.01, 0.4) 63 (0.1, 0.3)
1945 (756, 24) 617 (59, 6) 553 (5, 26) 140 (5, 5) 112 (1, 23) 107 (1, 8) 66 (0.4, 1) 45 (0.0002, 2) 539 (0.1) 86 (4) 54 (3) 565 (26, 0.4) 150 (32, 1) 98 (0.1, 2) 62 (0.7, 4) 1877 (783, 31) 536 (0.1, 9) 487 (12, 2) 114 (10, 5) 85 (0.8, 0.2) 52 (0.2, 0.4)
Exp. [42]
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B2 16 [CO] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ]
– – – – – – – – – – – –
2024 652 600 312 276 596 302 1899 – 533 258 130
2005 641 601 189 164 588 213 1902 – 511 – –
2001 624 599 135 108 577 160 1912 545 506 – –
a
Data in the parentheses are vibrational intensities, the first value in parentheses is infrared intensity and the second one is Raman active.
were performed with the use of Becke’s three parameters hybrid method with the Lee, Yang and Parr non-local functions [48,49]. The maximum values of the converged criterion are 0.000383 for maximum force, 0.000077 for RMS force, 0.001780 for maximum displacement and 0.000726 for RMS displacement (au. units), all geometries converged perfectly, and all optimized structure have only positive eigenvalues of the Hessian matrix, i.e. they are minima on the potential energy surface. The vibrational frequencies and intensities were computed at the same theoretical levels as that used in the geometry optimization. 3. Results and discussion 3.1. Optimized geometries The geometries of the complexes Os(CO)6 2+ , cisOs(CO)2 X4 2− , fac-Os(CO)3 X3 − and Os(CO)5 X+ were optimized under the restriction of Oh , C2v , C3v , and C4v symmetries, subsequent frequency calculations showed that these structures are indeed minima on the potential energy surface (number of imaginary frequencies is zero). The calculated bond lengths are given in Tables 1–3 and the fully optimized geometries of these complexes are shown in Fig. 1. As seen in the tables,
the calculated bond distances are dependent on the theoretical methods used. With the same basis set, the bond lengths ˚ longer than that calcalculated by B3LYP are ca. 0.033–0.047 A ˚ shorter for Os–C. For culated by RHF for C–O, 0.032–0.057 A Os–X bond distances, the bond lengths calculated by B3LYP ˚ shorter than that calculated by RHF in are ca. 0.004–0.028 A ˚ cis-Os(CO)2 X4 2− and fac-Os(CO)3 X3 − , while, 0.022–0.027 A longer in Os(CO)5 X+ . Using the same method, although SDD basis set is bigger than LanL2DZ, the calculated results are close to each other. Compared to Os(CO)6 2+ , the calculated bond distances of Os–C in the mixed carbonyl-halide complexes are shortened with halogen atoms substitution, especially, the Os–C bond that is trans to the halogen atoms. In complexes of cis-Os(CO)2 X4 2− , the bond distances of Os–X1 , ˚ shorter than which are trans to Os–C, are about 0.001–0.045 A Os–X3 . In the complexes Os(CO)5 X+ , the bond distances of Os–C at axial position, are slightly shorter than that at equatorial position, while the C–O distance at axial position, are slightly longer than that at equatorial position. For these compounds, the more halogen substituted, the shorter Os–C bond distance and the longer C–O bond distances were obtained. Although there is no structure data available for these complexes, the bonds parameter of Os(C6 H4 Cl–2)Cl(CO)(PPh3 )2
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Table 6 Calculated vibrational frequencies of fac-Os(CO)3 X3 − Method
Assignment
Os(CO)3 F3 −
Os(CO)3 Cl3 −
Os(CO)3 Br3 −
Os(CO)3 I3 −
RHF/LanL2DZ
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 6 A1 [␦XOsX ] 7 A2 [␦OsCO ] 8 A2 [␦XOsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 14 E[␦XOsC ] 15 E[␦XOsC ] 16 E[␦XOsC ]
2263 (411, 156)a 546 (146, 1) 457 (0.4, 4) 672 (65, 2) 213 (9, 1) 111 (0.01, 2) 546 125 2159 (1639, 148) 652 (25, 0.9) 566 (48, 0.2) 511 (66, 2) 435 (39, 1) 207 (1, 0.5) 133 (6, 1) 102 (0.001, 4)
2275 (703, 277) 653 (136, 5) 460 (1, 0.6) 319 (33, 7) 131 (2, 0.2) 114 (1, 5) 524 96 2200 (1203, 120) 631 (39, 4) 534 (25, 0.09) 439 (22, 0.8) 296 (33, 2) 130 (2, 0.7) 114 (0.01, 5) 98 (0.4, 0.4)
2267 (906, 344) 646 (156, 9) 462 (5, 0.6) 216 (11, 7) 121 (0.08, 2) 99 (0.02, 3) 517 84 2199 (1087, 110) 624 (45, 7) 525 (25, 0.3) 440 (14, 0.7) 194 (16, 3) 119 (0.0007, 2) 99 (0.02, 3) 72 (0.002, 1)
2254 (1179, 426) 643 (173, 15) 466 (11, 0.6) 174 (5, 7) 121 (0.3, 3) 96 (0.1, 2) 514 82 2191 (985, 99) 619 (54, 12) 522 (25, 0.7) 442 (8, 0.7) 153 (9, 5) 119 (0.5, 2) 96 (0.1, 2) 58 (0.002, 2)
RHF/SDD
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 6 A1 [␦XOsX ] 7 A2 [␦OsCO ] 8 A2 [␦XOsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 14 E[␦XOsC ] 15 E[␦XOsC ] 16 E[␦XOsC ]
2260 (409, 158) 545 (153, 1) 449 (0.1, 4) 665 (62, 2) 212 (9, 1) 109 (0.02, 2) 535 126 2159 (1592, 150) 644 (24, 0.6) 557 (51, 0.1) 510 (74, 1) 423 (33, 2) 207 (2, 0.6) 135 (6, 1) 100 (0.002, 4)
2271 (690, 240) 649 (128, 4) 455 (1, 0.8) 314 (32, 7) 132 (2, 0.2) 113 (0.8, 4) 518 100 2200 (1139, 111) 626 (38, 3) 528 (25, 0.2) 432 (21, 0.8) 289 (34, 2) 132 (1, 0.8) 114 (0.03, 4) 100 (0.3, 0.5)
2265 (897, 215) 641 (138, 5) 454 (4, 1) 214 (15, 8) 120 (0.03, 2) 85 (0.3, 3) 511 86 2200 (1009, 107) 620 (42, 6) 519 (21, 0.5) 431 (12, 0.6) 189 (20, 4) 118 (0.003, 1) 100 (0.06, 3) 75 (0.0, 1)
2254 (1179, 426) 643 (173, 15) 466 (11, 0.6) 174 (5, 7) 121 (0.3, 3) 68 (0.02, 4) 514 82 2191 (985, 99) 619 (54, 12) 522 (25, 0.7) 442 (8, 0.7) 153 (9, 5) 119 (0.5, 2) 96 (0.1, 2) 58 (0.003, 2)
B3LYP/LanL2DZ
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 6 A1 [␦XOsX ] 7 A2 [␦OsCO ] 8 A2 [␦XOsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 14 E[␦XOsC ] 15 E[␦XOsC ] 16 E[␦XOsC ]
2034 (297, 80) 537 (96, 6) 518 (6, 25) 635 (26, 2) 228 (3, 2) 102 (0.5, 5) 511 107 1925 (1262, 64) 621 (13, 0.2) 537 (44, 0.2) 510 (36, 11) 489 (11, 0.4) 212 (0.6, 1) 122 (4, 0.9) 95 (0.05, 6)
2043 (501, 182) 618 (86, 1) 509 (0.7, 7) 311 (16, 13) 127 (0.7, 0.8) 103 (0.2, 7) 487 77 1954 (1005, 78) 595 (26, 1) 509 (0.8, 7) 497 (26, 2) 285 (24, 4) 120 (0.3, 1) 102 (0.1, 7) 86 (0.2, 0.9)
2035 (621, 230) 607 (108, 3) 503 (0.003, 8) 208 (4, 9) 109 (0.03, 3) 78 (0.02, 5) 477 67 1951 (903, 84) 581 (33, 2) 504 (0.002, 8) 488 (23, 0.1) 184 (11, 4) 106 (0.003, 3) 85 (0.04, 4) 66 (0.0002, 2)
2024 (766, 290) 600 (131, 7) 499 (0.1, 7) 165 (1, 8) 106 (0.2, 3) 63 (0.05, 5) 468 66 1946 (801, 90) 569 (42, 5) 500 (0.1, 7) 482 (21, 0.7) 142 (6, 5) 108 (0.1, 4) 82 (0.3, 2) 53 (0.008, 3)
B3LYP/SDD
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 6 A1 [␦XOsX ] 7 A2 [␦OsCO ] 8 A2 [␦XOsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 14 E[␦XOsC ]
2031 (296, 77) 531 (55, 0.007) 510 (9, 24) 631 (24, 1) 227 (2, 2) 101 (0.5, 5) 502 108 1924 (1256, 67) 616 (13, 0.09) 531 (55, 0.01) 507 (42, 10) 483 (0.9, 0.4) 212 (0.6, 1)
2040 (489, 149) 614 (78, 0.6) 500 (5, 5) 309 (15, 13) 130 (0.7, 0.7) 103 (0.06, 6) 480 80 1951 (976, 77) 590 (26, 0.5) 500 (5, 5) 490 (24, 3) 283 (24, 3) 124 (0.2, 1)
2033 (628, 131) 603 (94, 1) 492 (0.2, 7) 207 (6, 12) 108 (0.0, 2) 83 (0.04, 4) 471 68 1949 (855, 92) 580 (29, 2) 492 (0.3, 7) 483 (20, 0.09) 180 (14, 5) 104 (0.0, 2)
2022 (764, 127) 595 (121, 3) 488 (0.2, 5) 164 (2, 9) 106 (0.04, 5) 65 (0.003, 4) 461 67 1945 (734, 93) 566 (40, 3) 489 (0.2, 5) 475 (17, 1) 140 (7, 6) 104 (0.3, 3)
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Table 6 (Continued ) Method
Exp. [42]
a
Assignment
Os(CO)3 F3 −
Os(CO)3 Cl3 −
Os(CO)3 Br3 −
Os(CO)3 I3 −
15 E[␦XOsC ] 16 E[␦XOsC ]
127 (5, 0.9) 92 (0.06, 6)
102 (0.2, 6) 88 (0.1, 1)
88 (0.007, 5) 69 (0.004, 2)
84 (0.2, 2) 53 (0.002, 3)
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 15 E[␦XOsC ]
– – – – – – – – – – –
2125 598 470 322 136 2040 624 499 468 281 105
2120 595 479 217 121 2040 613 494 465 200 101
2110 580 470 178 – 2040 597 488 462 159 –
Data in the parentheses are vibrational intensities, the first value in parentheses is infrared intensity and the second one is Raman active.
and (I)[Os(CO)3 (CNBu+ )]3 Mn(CO)5 can be used to compare the Os–C, Os–Cl and Os–I bond distance, in which Os–C bond ˚ Os–Cl is 2.466 A ˚ and Os–I is 2.777 A ˚ distances is 1.850 A, [50,51], therefore, our calculated bond distances are overestimated at all levels in some extent. Considering that the optimized geometries are ionic compounds without countercations involved and electron correction deficiencies of basis sets employed, it is estimated that the deviations of calculated geometry parameters from the observed ones are quite substantial. In general, longer bond lengths will result in lower vibrational frequencies and higher vibrational intensities. However, as seen below, the calculated results are not only dependent on the optimized geometries, but also on the theoretical method used. 3.2. Vibrational frequencies Vibrational analysis for the Oh symmetric complex Os(CO)6 2+ indicates that the complex has 33 fundamental vibrations (2A1g , 2Eg , T1g , 3T1u , 2T2g , 2T2u ), in which T1u are only infrared active, A1g , Eg and T2g are only Raman-active and T1g , T2u are inactive. The complexes of cis-Os(CO)2 X4 2− belong to C2v symmetry, 21 fundamental vibrational modes can be reduced to vib = 8A1 + 3A2 + 4B1 + 6B2 , in which, A1 , B1 and B2 are both infrared and Raman active, A2 frequencies are Raman active only. The calculated vibrational frequencies and intensities of these molecules are summarized in Tables 4 and 5, together with available experimental values. The assignment of the calculated vibrational fundamental frequencies is based on the symmetry, experimental values, vibrational intensities and calculated normal vibrational modes. Considering the C–O stretching vibration modes (1 A1g , 3 Eg and 6 T1u in Os(CO)6 2+ ; 1 A1 and 16 B2 in cisOs(CO)2 X4 2− ), the theoretical methods, rather than basis sets and displacement of halogens, dominate the accuracy of the calculated values. The frequencies calculated at B3LYP level give the results 31–84 cm−1 lower than the experimental values. However, the frequencies calculated at RHF levels are 145–215 cm−1 higher than the measured ones. Therefore, these results indicate that the B3LYP method is more suitable for calculation of the C–O stretching vibrational frequencies for
these complexes. The values obtained with LanL2DZ and SDD basis sets are close to each other. With varying from Cl to I, the calculated C–O frequencies slightly changed, this trend is consistent with that observed in the experiments. For 1 A1g of cis-Os(CO)2 X2 − , the vibrational frequencies are significantly lower than that in the complex of Os(CO)6 2+ , this result indicates that halogen substitution causes change in charge distribution and force constants of C–O bonds. In the far-infrared region, the experimental vibrational frequencies of Os(CO)6 2+ were well assignment by Wang et al. [52]. However, the assignment of cis-Os(CO)2 X4 2− are incompletely. Cleare and Griffith [42] assigned the experimental vibrational frequencies of ca. 650 cm−1 to A1 3 Os–C stretching mode and that of ca. 600 cm−1 to A1 2 Os–C–O bending vibration. However, according to our calculations, we’d better assign the experimental vibrational frequencies of 652, 641 and 624 cm−1 to A1 2 Os–C–O bending mode and that of 600, 601 and 599 cm−1 to Os–C stretching vibrational mode for cis-Os(CO)2 Cl4 2− , cis-Os(CO)2 Br4 2− and cis-Os(CO)2 I4 2− , respectively. With this assignments, the frequencies calculated at B3LYP level with two basis sets are in good agreement with the experimental ones, little better values are obtained at B3LYP/SDD level. With this method, the deviations of calculated data from experimental values are less than 9% for the Os–X stretching vibrational modes, and less than 8% for Os–C stretching vibrational modes for Os(CO)6 2+ and cisOs(CO)2 X4 2+ . With halogen vary from F to I, the vibrational frequencies of Os–C stretching mode and Os–C–N bending mode slightly decreased. The vibrational frequencies of [Os(CO)6 ]2+ has been calculated by Thiel and co-workers with BP86/ECP2 [29], our calculation is very close to the results. Since there is no scale factor used in these calculations for comparison with experimental data, it is reasonable to believe that B3LYP/SDD calculation for the vibrational frequencies of Os(CO)6 2+ and cis-Os(CO)2 X4 2− provides reliable data for the vibrational modes and it is believable for further calculations of vibrational frequencies. In C3v symmetry fac-Os(CO)3 X3 -type complexes, the CO groups are trans to the halogen atoms. Twenty-four fundamental vibrational modes are reduced to vib = 6A1 + 2A2 + 8E, in
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Table 7 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of Os(CO)5X+ Method
Assignment
Os(CO)5 F+
Os(CO)5 Cl+
Os(CO)5 Br+
Os(CO)5 I+
RHF/LanL2DZ
1 A1 [CO ] 2 A1 [CO ] 3 A1 [␦OsCO ] 4 A1 [OsC ] 5 A1 [OsC ] 6 A1 [OsX ] 7 A1 [␦COsC ] 8 A2 [OsC ] 9 B1 [␦OsCO ] 10 B1 [␦COsC ] 11 B2 [CO ] 12 B2 [␦OsCO ] 13 B2 [␦OsCO ] 14 B2 [␦COsC ] 15 E[CO ] 16 E[␦OsCO ] 17 E[␦OsCO ] 18 E[␦OsCO ] 19 E[OsC ] 20 E[␦COsX ] 21 E[␦COsX ] 22 E[␦COsC ]
2431 (0.1, 225)a 2332 (693, 136) 605 (145, 2) 395 (13, 1) 379 (4, 0.4) 575 (145, 2) 112 (0.005, 0.4) 373 523 (0, 5) 109 (0, 6) 2397 (222) 549 (0, 0.01) 370 (0, 2) 80 (0, 0.2) 2378 (923, 13) 593 (99, 0.3) 557 (0.001, 2) 437 (0.3, 1) 324 (22, 1) 159 (7, 0.05) 113 (0.1, 1) 97 (0.03, 3)
2423 (26, 240) 2336 (668, 167) 607 (143, 1) 405 (24,2) 390 (1, 9) 357 (24, 8) 120 (0.1, 0.1) 379 530 (0, 5) 111 (0, 6) 2387 (213) 553 (0, 0.2) 380 (0, 1) 88 (0, 0.03) 2373 (949, 2) 597 (102, 0.5) 555 (3, 4) 438 (1, 0.2) 340 (23, 0.2) 126 (2, 0.04) 108 (1, 5) 99 (0.4, 0.7)
2417 (64, 250) 2336 (658, 190) 610 (61, 2) 399 (11, 1) 393 (0.1, 1) 241 (7, 9) 121 (0.3, 0.01) 381 532 (0, 5) 111 (0, 6) 2381 (216) 553 (0, 0.5) 384 (0, 1) 91 (0, 0.01) 2367 (984, 0.05) 598 (101, 0.4) 552 (6, 6) 438 (2, 0.3) 345 (24, 0.03) 121 (0.4, 0.3) 103 (0.1, 4) 86 (1, 0.5)
2408 (138, 260) 2334 (643, 222) 613 (184, 5) 398 (10, 0.4) 394 (4, 2) 190 (3, 11) 122 (0.7, 0.4) 383 534 (0, 4) 111 (0, 6) 2372 (223) 553 (0, 1) 389 (0, 1) 93 (0, 0.0002) 2358 (1039, 2) 600 (100, 0.4) 550 (9, 8) 438 (4, 0.3) 351 (27, 0.04) 120 (0.2, 0.5) 104 (0.04, 4) 79 (0.4, 0.5)
RHF/SDD
1 A1 [CO ] 2 A1 [CO ] 3 A1 [␦OsCO ] 4 A1 [OsC ] 5 A1 [OsC ] 6 A1 [OsX ] 7 A1 [␦COsC ] 8 A2 [OsC ] 9 B1 [␦OsCO ] 10 B1 [␦COsC ] 11 B2 [CO ] 12 B2 [␦OsCO ] 13 B2 [␦OsCO ] 14 B2 [␦COsC ] 15 E[CO ] 16 E[␦OsCO ] 17 E[␦OsCO ] 18 E[␦OsCO ] 19 E[OsC ] 20 E[␦COsX ] 21 E[␦COsX ] 22 E[␦COsC ]
2425 (0.01, 226) 2326 (680, 136) 602 (5, 1) 387 (12, 1) 375 (2, 0.5) 575 (183, 2) 110 (0.01, 0.4) 363 538 (0, 0.04) 106 (0, 0, 5) 2389 (0, 0, 218) 514 (0, 4) 371 (0, 2) 79 (0, 0.1) 2373 (890, 11) 585 (94, 0.4) 551 (0.3, 2) 428 (0.2, 0.7) 307 (18, 1) 160 (7, 0.1) 110 (0.03, 1) 95 (0.03, 3)
2418 (24, 231) 2332 (661, 167) 595 (140, 1) 399 (3, 2) 383 (1, 1) 349 (24, 7) 116 (0.03, 0.1) 368 540 (0, 0.2) 108 (0, 5) 2385 (0, 201) 519 (0, 4) 379 (0, 1) 86 (0, 0.04) 2369 (898, 2) 587 (99, 0.5) 548 (1, 3) 428 (0.6, 0.3) 318 (19, 0.2) 125 (3, 0.1) 107 (0.7, 4) 96 (0.2, 1)
2411 (56, 225) 2329 (654, 193) 599 (153, 1) 392 (8, 1) 384 (0.4, 1) 237 (10, 9) 117 (0.2, 0.1) 370 541 (0, 0. 3) 108 (0, 5) 2377 (0, 202) 521 (0, 4) 381 (0, 1) 89 (0, 0.02) 2361 (925, 0.01) 587 (96, 0.5) 545 (4, 5) 428 (2, 0.3) 322 (20, 0.02) 118 (0.6, 0.2) 101 (0.1, 4) 87 (0.8, 0.4)
2403 (122, 220) 2328 (639, 225) 601 (180) 390 (10, 1) 388 (2, 2) 187 (4, 10) 119 (0.6, 0.6) 372 539 (0, 1) 108 (0, 5) 2370 (0, 204) 524 (0, 4) 386 (0, 0.6) 92 (0, 0.01) 2354 (970, 2) 589 (94, 0.5) 542 (8, 6) 427 (3, 0.3) 327 (23, 0.02) 117 (0.4, 0.4) 101 (0.1, 4) 79 (0.5, 0.5)
B3LYP/LanL2DZ
1 A1 [CO ] 2 A1 [CO ] 3 A1 [␦OsCO ] 4 A1 [OsC ] 5 A1 [OsC ] 6 A1 [OsX ] 7 A1 [␦COsC ] 8 A2 [OsC ] 9 B1 [␦OsCO ] 10 B1 [␦COsC ] 11 B2 [CO ] 12 B2 [␦OsCO ] 13 B2 [␦OsCO ] 14 B2 [␦COsC ] 15 E[CO ] 16 E[␦OsCO ] 17 E[␦OsCO ] 18 E[␦OsCO ]
2184 (0.02, 223) 2063 (608, 137) 593 (86, 1) 452 (2, 14) 434 (16, 3) 532 (23, 5) 100 (0.1, 0.5) 364 500 (0, 1) 104 (0, 9) 2129 (0, 315) 538 (0, 0.2) 418 (0, 0.2) 70 (0, 0.2) 2101 (894, 18) 584 (70, 0.03) 541 (0.3, 0.4) 421 (0.1, 0.3)
2177 (16, 225) 2067 (589, 170) 591 (110, 0.5) 456 (3, 13) 443 (5, 4) 332 (9, 10) 108 (0.5, 0.1) 367 504 (0, 1) 105 (0, 9) 2124 (0, 286) 526 (0, 0.03) 426 (0, 0.4) 74 (0, 0.05) 2099 (883, 6) 583 (72, 0.04) 532 (4, 2) 414 (0.1, 0.4)
2170 (39, 228) 2065 (585, 201) 590 (123, 0.6) 455 (3, 15) 442 (6, 2) 220 (3, 7) 110 (0.7, 0.06) 368 504 (0, 0.8) 105 (0, 9) 2118 (0, 278) 519 (0, 0.3) 428 (0, 0.6) 77 (0, 0.02) 2094 (901, 2) 583 (70, 0.02) 526 (7, 3) 410 (0.7, 0.8)
2161 (86, 237) 2063 (584, 249) 591 (140, 1) 455 (2, 18) 439 (8, 1) 172 (1, 6) 111 (1, 0.4) 370 507 (0, 0.6) 105 (0, 9) 2109 (0, 270) 513 (0, 1) 433 (0, 1) 80 (0, 0.01) 2085 (932, 0.02) 584 (68, 0.002) 521 (9, 5) 409 (2, 2)
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Table 7 (Continued ) Method
B3LYP/SDD
a
Assignment
Os(CO)5 F+
Os(CO)5 Cl+
Os(CO)5 Br+
Os(CO)5 I+
19 20 21 22
346 (50, 1) 145 (0.7, 0.03) 104 (0.02, 3) 92 (0.2, 4)
365 (57, 1) 114 (0.2, 0.3) 95 (0.03, 7) 89 (0.5, 0.1)
370 (46, 1) 111 (0.03, 1) 95 (0.01, 5) 71 (0.4, 0.9)
376 (45, 1) 110 (0.01, 1) 96 (0.0004, 4) 65 (0.2, 0.5)
2177 (0.03, 225) 2057 (614, 138) 585 (82, 0.8) 448 (2, 13) 432 (14, 4) 544 (46, 6) 99 (0.1, 0.5) 352 491 (0, 0.7) 101 (0, 9) 2125 (0, 318) 528 (0, 0.2) 418 (0, 0.2) 68 (0, 0.2) 2096 (883, 18) 576 (70, 0.03) 537 (0.02, 0.3) 413 (0.1, 0.2) 337 (47, 1) 150 (1, 0.1) 102 (0.001, 3) 90 (0.2, 3)
2170 (15, 219) 2061 (594, 172) 581 (110, 0.6) 451 (3, 12) 437 (4, 5) 327 (9, 10) 105 (0.3, 0.1) 355 495 (0, 0.6) 102 (0, 9) 2120 (0, 281) 515 (0, 0.005) 424 (0, 0.4) 73 (0, 0.1) 2094 (861, 6) 575 (72, 0.03) 527 (3, 1) 404 (0.3, 0.5) 352 (43, 1) 114 (0.4, 0.1) 95 (0.1, 7) 88 (0.3, 0.3)
2163 (36, 210) 2058 (593, 206) 582 (120, 0.7) 448 (2, 16) 436 (6, 3) 218 (4, 7) 107 (0.6, 0.1) 356 496 (0, 0.7) 102 (0, 9) 2113 (0, 270) 510 (0, 0.1) 427 (0, 0.7) 75 (0, 0.04) 2087 (875, 2) 575 (69, 0.02) 522 (5, 2) 402 (0.7, 0.8) 356 (43, 1) 109 (0.1, 1) 92 (0.0001, 5) 73 (0.4, 0.8)
2155 (79, 206) 2056 (593, 252) 580 (142, 1) 449 (1, 20) 434 (7, 1) 171 (1, 6) 109 (1, 0.6) 359 499 (0, 0.6) 103 (0, 8) 2105 (0, 257) 501 (0, 0.6) 430 (0, 1) 78 (0, 0.02) 2079 (897, 0.04) 575 (67, 0.002) 515 (8, 4) 398 (1, 2) 362 (41, 1) 108 (0.1, 1) 93 (0.004, 4) 66 (0.3, 0.5)
E[OsC ] E[␦COsX ] E[␦COsX ] E[␦COsC ]
1 A1 [CO ] 2 A1 [CO ] 3 A1 [␦OsCO ] 4 A1 [OsC ] 5 A1 [OsC ] 6 A1 [OsX ] 7 A1 [␦COsC ] 8 A2 [OsC ] 9 B1 [␦OsCO ] 10 B1 [␦COsC ] 11 B2 [CO ] 12 B2 [␦OsCO ] 13 B2 [␦OsCO ] 14 B2 [␦COsC ] 15 E[CO ] 16 E[␦OsCO ] 17 E[␦OsCO ] 18 E[␦OsCO ] 19 E[OsC ] 20 E[␦COsX ] 21 E[␦COsX ] 22 E[␦COsC ]
Data in the parentheses are vibrational intensities, the first value in parentheses is infrared intensity and the second one is Raman active.
which A1 , and E modes are both infrared active and Raman active, the calculated vibrational frequencies and intensities of the complexes are listed in Table 6. Similar to the calculated bond distances increased from F to I, the calculated vibrational frequencies of Os–X are significantly dependent on substitution of halogen atoms. Using B3LYP/SDD method, 467 and 343 cm−1 decreased for the Os–X stretching vibrational modes of 4 A1 and 13 E, respectively, when halogen changes from F to I. The calculated 4 Os–X stretching vibrational frequencies of A1 symmetry in fac-Os(CO)3 X3 − are 24–135 cm−1 higher than that in the cis-Os(CO)2 X4 2− , while the calculated 13 Os–X stretching vibrational frequencies of E symmetry in fac-Os(CO)3 X3 − are 32–43 cm−1 higher than those in cis-Os(CO)2 X4 2− B2 symmetry 19 . Similar trends can be found in other methods. The complexes of Os(CO)5 X+ belong to C4v symmetry. There are 30 fundamental vibrations reduced to vib = 7A1 + A2 + 2B1 + 4B2 + 8E, in which, A1 and E are both infrared and Raman active, B1 and B2 are Raman active only. In these complexes, the CO group arrange in two positions, one of them is trans to the halogen atom and the others are neighbor to the halogen atom. The calculated vibrational frequencies and intensities of the complexes are listed in Table 7. For the C–O that are neighbor to halogen atoms, the theoretical methods, rather than basis sets and displacement of halogens, dominate the calculated values of Os–C stretching vibrational modes, there is no significant change with varying from F to I. However, when CO group and halogen atom are in the trans position, the Os–C stretching and C–Os–C bending are not only dependent on the theoretical methods but also on the substituted halogen atoms.
3.3. Vibrational intensities The intensity of antisymmetric vibrations may be used as a measurement of the extent of bonding in this type of complexes [53]. As shown in parentheses of Tables 4–7, the calculated intensities are mainly dependent on the theoretical methods, rather than basis sets. In these complexes, the vibrational intensities calculated at B3LYP level correctly give relative tendency of the major intensities in the experimental vibrational spectra. For the complexes studied here, the IR vibrational intensities of A1 C–O stretching vibrational modes increase significantly from Cl to I, indicating that the C–O -bond strength increases in the order (C–O)Cl < (C–O)Br < (C–O)I. The heavier halogens donate their -bonding electrons more to the Os atom because of their smaller electronegativity, therefore, a tendency for back of -bonding electrons to the carbonal ligand would be expected. 4. Conclusion This investigation indicates that B3LYP method is superior to RHF method for the calculation of C–O stretching vibrational mode and far-infrared frequencies in heavy atom containing mixed carbonyl-halide Os(II) complexes, with both basis sets concerned. For a given method, the calculated data are slightly improved by SDD basis set. In infrared frequency region, the C–O stretching vibrational frequencies calculated at B3LYP level with two basis sets are in good agreement with the observed values with deviations less than 5%. In the far-infrared region,
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the B3LYP/SDD method achieved the best results with deviations less than 9% for Os–X stretching and less than 8% for Os–C stretching vibrational frequencies. These deviations are quite smooth for a given type of vibration. The C–O stretching vibrational frequencies and Os–X, Os–C stretching frequencies and the OsCN bending vibrational frequencies calculated at B3LYP/SDD level, are accurate enough with the deviations in the same order as anharmonicity corrections and effect from solvent or matrix or crystal. Therefore, this study confirms again that the theoretical calculation of vibrational frequencies for metal complexes is quite useful for the vibrational assignment and for predicting new vibrational frequencies. Acknowledgments This work was supported by the Natural Science Foundation of Jiangsu Educational Department (Nos. 04KJB 150015). References [1] L. Mond, C. Langer, F.J. Quincke, Chem. Soc. (1890) 749. [2] H. Werner, Angew. Chem. 102 (1990) 1109; H. Werner, Angew. Chem., Int. Ed. Engl. 29 (1990) 1077. [3] J.E. Ellis, Adv. Organomet. Chem. 31 (1990) 1. [4] E.P. Kundig, M. Moskovits, G.A. Ozin, Angew. Chem., Int. Ed. Engl. 14 (1975) 292. [5] G.A. Ozin, Acc. Chem. Res. 10 (1977) 21. [6] P.K. Hurlburt, J.J. Rack, J.S. Luck, S.F. Dec, J.D. Webb, O.P. Anderson, S.H. Strauss, J. Am. Chem. Soc. 116 (1994) 10003. [7] E.I. Solomon, P.M. Jones, J.A. May, Chem. Rev. 93 (1993) 2623. [8] A. Sen, Acc. Chem. Res. 26 (1993) 303. [9] K.C. Waugh, Catal. Today 15 (1992) 51. [10] M.A. Vannice, Catal. Today 12 (1992) 255. [11] L. Guczi (Ed.), Studies in Surface Science and Catalysis; New Trends in CO Activation 64, Elsevier, Amsterdam, 1991. [12] G. Henrici-Oliv´e, S. Oliv´e, The Chemistry of the Catalyzed Hydrogenation of Carbon Monoxide, Springer-Verlag, Berlin, 1983. [13] P.C. Ford (Ed.), Catalytic Activation of Carbon Monoxide; ACS Symposium Series 152, American Chemical Society, Washington, DC, 1981. [14] A.W. Ehlers, S. Dapprich, S.F. Vyboishchikov, G. Frenking, Organometallics 15 (1996) 105. [15] M.S. Dewar, Bull. Soc. Chim. Fr. 18 (1951) C71. [16] J. Chatt, L.A. Duncanson, J. Chem. Soc. (1953) 2939. [17] R. Hoffmann, M.M.L. Chen, D.L. Thorn, Inorg. Chem. 16 (1977) 503.
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Theoretical studies on vibrational spectra of some mixed carbonyl-halide complexes of Osmium(II) Jianying Zhao a , Yu Zhang a,∗ , Guodong Tang a , Longgen Zhu b a
Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials, Department of Chemistry, Huaiyin Teachers College, Huai’an 223001, Jiangsu, PR China b State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093, Jiangsu, PR China Received 5 February 2005; received in revised form 30 May 2005; accepted 3 December 2005
Abstract The vibrational spectra of Os(CO)6 2+ and some of its mixed carbonyl-halide complexes, cis-Os(CO)2 X4 2− , fac-Os(CO)3 X3 − and Os(CO)5 X+ (X = F, Cl, Br and I), have been systematically investigated by ab initio RHF and density functional B3LYP methods with LanL2DZ and SDD basis sets. The calculated vibrational frequencies of complexes Os(CO)6 2+ , cis-Os(CO)2 X4 2− and fac-Os(CO)3 X3 − are evaluated via comparison with the experimental values. In infrared frequency region, the C–O stretching vibrational frequencies calculated at B3LYP level with two basis sets are in good agreement with the observed values with deviations less than 5%. In the far-infrared region, the B3LYP/SDD method achieved the best results with deviations less than 9% for Os–X stretching and less than 8% for Os–C stretching vibrational frequencies. The vibrational frequencies for Os(CO)5 X+ that have not been experimentally reported were predicted. © 2005 Elsevier B.V. All rights reserved. Keywords: Vibrational frequencies; Ab initio RHF; Density functional B3LYP; Mixed carbonyl-halide complexes of Os(II)
1. Introduction Since the first transition-metal carbonyl complex, nickel tetracarbonyl, was synthesized by Mond et al. [1]. These type of complexes have become one of the most important classes of inorganic compounds. These complexes are not just of interest in academic research [2–6], they are also used by industry as important homogeneous and heterogeneous catalysts [7–14]. In these complexes, the nature of the bonds between transition metals and carbon monoxides were well established. The synergic bonding model due to Dewar [15] and Chatt and Duncanson [16] has a central role in organometallic chemistry. The power of this model has been demonstrated by Hoffmann and co-workers, who showed that the structure and reactivity of many transitionmetal complexes can be understood and, to a certain extent, can even be predicted using the -donation -back-donation picture in conjunction with semiempirical calculations [17–21]. Frenking et al. [22–26] have extensively studied the structures
∗
Corresponding author. Tel.: +86 5173511083; fax: +86 5173942349. E-mail address: [email protected] (Z. Yu).
1386-1425/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.saa.2005.12.001
and bonding of these type complexes, especially OC → M -donation and metal → CO -back-donation. Vibrational spectra is a very important analytical tool to experimentally investigate these kind of transition metal complex, the bond properties can be reflected from vibrational frequencies, vibrational intensities and vibrational force constance, so, the vibrational properties of many transition metal complexes were studied using quantum chemistry methods, such as ab initio Hartree–Fock (HF), Møllar–Plesset (MP2) and density functional theory (DFT) [27–40]. Andrews has reviewed the investigations on the spectroscopic and theoretical of vibrational frequencies in transition metal carbonyl cations, neutrals, and anions recently [41]. Some of the vibrational frequencies of mixed carbonyl-halide complexes of Os(II) were experimentally investigated by Cleare and Griffith [42], therefore, we can use theoretical methods with different basis sets to carry out systematic calculations for their vibrational frequencies and compare them with the experimental values. The purposes for this work are to gain further insight into the effect of theoretical methods with different basis sets used on calculations of structure parameters and vibrational frequencies for mixed carbonyl-halide complexes of Os(II), in order to iden-
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tify the preferred computational approach and to establish the level of accuracy that can be reached, and to predict vibrational frequencies for the complexes, in which experimental assignments were uncertain and experimental data were absent.
2. Calculations The geometries of the molecules have been optimized with Oh , C2v , C3v , and C4v symmetries for Os(CO)6 2+ , cis-
Table 1 Optimized bond lengths of Os(CO)6 2+ and cis-Os(CO)2 X4 2− Os(CO)6 2+
Os(CO)2 F4 2−
Os(CO)2 Cl4 2−
Os(CO)2 Br4 2−
Os(CO)2 I4 2−
1.878 1.166 2.063 2.087
1.904 1.152 2.573 2.574
1.911 1.150 2.732 2.744
1.916 1.149 2.904 2.933
2.097 1.117 – –
1.883 1.164 2.073 2.090
1.909 1.151 2.575 2.578
1.916 1.148 2.714 2.728
1.920 1.147 2.904 2.938
ROs–C RC–O ROs−X1 ROs−X3
2.037 1.150 – –
1.846 1.212 2.051 2.067
1.850 1.198 2.546 2.556
1.854 1.196 2.706 2.729
1.859 1.195 2.878 2.920
ROs–C RC–O ROs−X1 ROs−X3
2.044 1.150 – –
1.851 1.211 2.063 2.069
1.855 1.197 2.538 2.554
1.859 1.194 2.684 2.712
1.864 1.193 2.874 2.919
Method
Bond
RHF/LanL2DZ
ROs–C RC–O ROs−X1 ROs−X3
RHF/SDD
ROs–C RC–O ROs−X1 ROs−X3
B3LYP/LanL2DZ
B3LYP/SDD
– – – –
Table 2 Optimized bond lengths of fac-Os(CO)3 X3 − Method
Bond lengths
Os(CO)3 F3 −
Os(CO)3 Cl3 −
Os(CO)3 Br3 −
Os(CO)3 I3 −
RHF/LanL2DZ
Os–X Os–C C–O
2.036 1.943 1.144
2.526 1.947 1.140
2.685 1.949 1.140
2.863 1.949 1.141
RHF/SDD
Os–X Os–C C–O
2.044 1.949 1.143
2.529 1.950 1.139
2.668 1.952 1.139
2.870 1.953 1.140
B3LYP/LanL2DZ
Os–X Os–C C–O
2.024 1.900 1.183
2.518 1.898 1.179
2.683 1.900 1.179
2.867 1.902 1.180
B3LYP/SDD
Os–X Os–C C–O
2.032 1.908 1.183
2.514 1.904 1.179
2.663 1.906 1.179
2.866 1.908 1.179
Table 3 Optimized bond lengths of Os(CO)5 X+ Method
Bond
Os(CO)5 F+
Os(CO)5 Cl+
Os(CO)5 Br+
Os(CO)5 I+
RHF/LanL2DZ
ROs–C RC–O ROs–X
2.062, 2.018 1.121, 1.127 2.011
2.055, 2.012 1.121, 1.126 2.467
2.052, 2.014 1.122, 1.126 2.622
2.048, 2.017 1.123, 1.126 2.799
RHF/SDD
ROs–C RC–O ROs–X
2.071, 2.022 1.122, 1.127 2.013
2.065, 2.013 1.122, 1.126 2.468
2.062, 2.018 1.123, 1.127 2.601
2.058, 2.021 1.123, 1.127 2.802
B3LYP/LanL2DZ
ROs–C RC–O ROs–X
2.009, 1.963 1.154, 1.163 2.037
2.006, 1.957 1.155, 1.162 2.492
2.004, 1.959 1.156, 1.162 2.650
2.001, 1.963 1.157, 1.162 2.827
B3LYP/SDD
ROs–C RC–O ROs–X
2.018, 1.966 1.155, 1.164 2.037
2.015, 1.961 1.155, 1.163 2.490
2.013, 1.965 1.156, 1.163 2.628
2.010, 1.968 1.157, 1.163 2.825
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503
Fig. 1. Optimized geometries of: (a) Os(CO)6 2+ ; (b) cis-Os(CO)2 X4 2− ; (c) fac-Os(CO)3 X3 − ; (d) Os(CO)5 X+ .
Os(CO)2 X4 2− , fac-Os(CO)3 X3 − and Os(CO)5 X+ (X = F, Cl, Br and I), respectively. These geometry optimization procedures proceed in two steps—firstly the geometries were constructed by MM+ molecular dynamics from HyperChem 6.0 package
[43], and secondly, optimized by RHF and DFT levels of theory with LanL2DZ (Los Alamos ECP plus double-zeta) [44,45] and SDD (Stuttgart/Dresden effective core potential) [46] basis sets using Gaussian 98W program package [47]. DFT calculations
Table 4 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of Os(CO)6 2+ Assignment
A1g 1 [CO] A1g 2 [OsC] Eg 3 [CO] Eg 4 [OsC] T1g 5 [␦OsCO] T1u 6 [CO] T1u 7 [␦OsCO] T1u 8 [OsC] T1u 9 [␦COsC] T2g 10 [␦OsCO] T2g 11 [␦COsC] T2u 12 [␦OsCO] T2u 13 [␦COsC] a
RHF
B3LYP
Exp.[51]
LanL2DZ
SDD
LanL2DZ
SDD
–
– – – – – – – – – – – – –
2462 (220)a 360 (9) 2429 (173) 355 (0.9) 358 2417 (627) 574 (110) 311 (11) 118 (0.1) 499 (5) 105 (5) 525 90
2211 (222) 427 (13) 2159 (280) 397 (0.04) 359 2138 (599) 578 (90) 348 (42) 116 (0.1) 488 (2) 104 (8) 522 86
2204 (227) 423 (14) 2155 (282) 397 (0.02) 350 2132 (590) 572 (91) 339 (37) 113 (0.02) 482 (1) 102 (8) 515 83
2259 – 2218 – – 2190 562 346 – – 132 – –
Data in the parentheses are vibrational intensities.
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Table 5 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of cis–Os(CO)2 X4 2− Method
Assignment
Os(CO)2 F4 2−
Os(CO)2 Cl4 2−
Os(CO)2 Br4 2−
Os(CO)2 I4 2−
RHF/LanL2DZ
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] A1 6 [␦XOsX ] A1 7 [␦COsC ] A1 8 [␦XOsX ] A2 9 [␦OsCO ] A2 10 [␦XOsX ] A2 11 [␦COsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B1 14 [␦COsX ] B1 15 [␦COsX ] B2 16 [CO ] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ] B2 21 [␦COsX ]
2098 (879, 94)a 726 (30, 1) 538 (15, 9) 493 (148, 4) 457 (7, 2) 218 (8, 1) 186 (2, 0.2) 112 (0.5,5) 630 (0.3) 201 (0.3) 105 (2) 654 (39, 0.1) 456 (191, 0.01) 212 (9, 0.6) 119 (5, 1) 1967 (2599, 72) 590 (31, 1) 516 (94, 3) 450 (45, 0.3) 200(3, 1) 123 (3, 0.4)
2166 (1007, 276) 685 (68, 4) 495 (4, 4) 277 (38, 4) 254 (9, 4) 129 (3, 0.5) 114 (1, 5) 97 (1, 0.3) 591 (0.1) 116 (4) 94 (2) 607 (52, 0.3) 268 (98, 0.1) 128 (2, 1) 106 (0.1, 4) 2084 (1746, 94) 548 (22, 0.2) 474 (45, 0.7) 246 (36, 0.4) 125 (4, 1) 90 (0.01, 0.2)
2173 (1081, 399) 671 (80, 9) 489 (5, 7) 182 (17, 3) 154 (2, 4) 121 (0.04, 3) 82 (0.2, 2) 61 (0.2, 0.7) 581 (0.5) 93 (3) 71 (2) 596 (47, 0.4) 186 (53, 0.04) 110 (0.1, 0.7) 78 (0.1, 4) 2102 (1509, 87) 537 (21, 0.4) 468 (29, 1) 156 (18, 1) 99 (0.1, 0.8) 69 (0.03, 0.1)
2170 (1184, 591) 662 (92, 19) 486 (6, 14) 146 (8, 2) 119 (1, 4) 110 (1, 5) 65 (0.1, 1) 46 (0.1, 1) 576 (2) 97 (2) 55 (3) 593 (46, 1) 152 (39, 0.1) 111 (0.7, 1) 61 (0.6, 5) 2109 (1321, 73) 531 (21, 1) 465 (19, 2) 118 (12, 1) 93 (0.3, 0.7) 58 (0.03, 0.1)
RHF/SDD
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] A1 6 [␦XOsX ] A1 7 [␦COsC ] A1 8 [␦XOsX ] A2 9 [␦OsCO ] A2 10 [␦XOsX ] A2 11 [␦COsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B1 14 [␦COsX ] B1 15 [␦COsX ] B2 16 [CO ] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ] B2 21 [␦COsX ]
2103 (897, 98) 719 (28, 0.3) 529 (167, 8) 489 (143, 4) 455 (11, 1) 215 (8, 2) 186 (1, 0.3) 109 (0.5, 5) 619 (0.3) 201 (0.4) 103 (2) 644 (37, 0.01) 452 (210, 0.1) 212 (8, 0.6) 117 (6, 1) 1976 (2529, 81) 578 (29, 1) 500 (119, 2) 445 (32, 0.05) 204 (3, 1) 124 (3, 0.3)
2169 (956, 225) 678 (63, 3) 485 (3, 5) 272 (35, 4) 246 (10, 2) 130 (1, 0.6) 113 (0.4, 4) 98 (1, 0.1) 583 (0.02) 118 (3) 95 (1) 601 (50, 0.1) 259 (95, 0.1) 128 (3, 1) 107 (0.1, 4) 2091 (1611, 88) 539 (22, 0.4) 461 (45, 0.5) 238 (37, 0.1) 127 (3, 1) 93 (0.01, 0.2)
2179 (1023, 192) 666 (70, 6) 477 (4, 7) 180 (20, 4) 148 (4, 5) 119 (0.1, 2) 83 (0.2, 1) 62 (0.2, 0.8) 573 (0.3) 96 (3) 72 (1) 590 (41, 0.3) 177 (67, 0.4) 111 (0.1, 0.7) 78 (0.2, 3) 2114 (1325, 80) 528 (17, 0.6) 455 (25, 0.6) 149 (24, 1) 102 (0.1, 1) 71 (0.02, 0.1)
2179 (1057, 225) 655 (83, 11) 475 (4, 12) 144 (9, 3) 118 (1, 5) 107 (2, 6) 66 (0.6, 1) 47 (0.01, 1) 567 (1) 99 (2) 55 (2) 584 (46, 0.4) 147 (42, 1) 111 (2, 1) 62 (0.6, 3) 2124 (1084, 53) 522 (17, 1) 452 (14, 1) 114 (14, 3) 94 (1, 0.2) 58 (0.04, 0.2)
B3LYP/LanL2DZ
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] A1 6 [␦XOsX ] A1 7 [␦COsC ] A1 8 [␦XOsX ] A2 9 [␦OsCO ] A2 10 [␦XOsX ] A2 11 [␦COsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B1 14 [␦COsX ] B1 15 [␦COsX ] B2 16 [CO ] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ] B2 21 [␦COsX ]
1892 (545, 30) 676 (8, 0.5) 574 (15, 30) 494 (102, 12) 453 (20, 6) 225 (3, 1) 191 (0.8, 0.5) 105 (1, 6) 594 (1) 203 (1) 101 (3) 624 (9, 0.1) 463 (152, 0.2) 217 (3, 2) 114 (8, 2) 1795 (1446, 16) 570 (2, 15) 548 (20, 2) 444 (59, 1) 207 (3, 0.5) 114 (3, 0.4)
1940 (709, 114) 650 (36, 2) 573 (6, 29) 278 (18, 19) 255 (14, 12) 129 (1, 0.4) 107 (0.01, 8) 99 (0.1, 0.4) 570 (0.2) 117 (7) 85 (3) 595 (24, 0.2) 277 (78, 0.04) 125 (0.1, 4) 100 (1, 5) 1859 (1191, 27) 561 (1, 18) 516 (16, 0.5) 243 (32, 1) 125 (1, 0.6) 79 (0.3, 0.3)
1943 (759, 160) 635 (49, 5) 570 (6, 29) 180 (8, 4) 154 (3, 15) 112 (0.005, 4.2) 81 (0.1, 3) 60 (0.009, 1) 558 (0.05) 85 (7) 69 (1) 581 (25, 0.02) 190 (41, 0.003) 98 (0.1, 1) 76 (0.4, 7) 1868 (1054, 30) 556 (0.5, 17) 504 (15, 1) 153 (14, 2) 92 (0.03, 0.6) 61 (0.1, 0.2)
1942 (803, 217) 622 (63, 121) 566 (7, 29) 141 (4, 5) 113 (0.5, 17) 108 (0.6, 7) 74 (0.5, 3) 44 (0.001, 2) 548 (0.01) 85 (5) 53 (4) 574 (26, 0.01) 153 (28, 0.04) 98 (0.003, 2) 60 (1, 7) 1872 (920, 32) 550 (0.1, 16) 496 (15, 2) 116 (8, 3) 83 (0.6, 0.6) 52 (0.3, 0.3)
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Table 5 (Continued ) Method
Assignment
Os(CO)2 F4 2−
Os(CO)2 Cl4 2−
Os(CO)2 Br4 2−
Os(CO)2 I4 2−
B3LYP/SDD
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] A1 6 [␦XOsX ] A1 7 [␦COsC ] A1 8 [␦XOsX ] A2 9 [␦OsCO ] A2 10 [␦XOsX ] A2 11 [␦COsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B1 14 [␦COsX ] B1 15 [␦COsX ] B2 16 [CO ] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ] B2 21 [␦COsX ]
1897 (566, 22) 670 (7, 0.2) 565 (13, 27) 496 (98, 13) 457 (30, 4) 222 (3, 1) 191 (0.6, 0.5) 102 (1, 6) 585 (1) 202 (1) 96 (3) 616 (9, 0.2) 466 (178, 0.01) 215 (3, 1) 111 (8, 2) 1799 (1440, 18) 559 (6, 14) 538 (20, 1) 445 (62, 0.3) 210 (3, 0.5) 116 (3, 0.4)
1941 (680, 71) 645 (33, 0.8) 562 (5, 28) 275 (16, 15) 251 (14, 10) 130 (1, 0.4) 107 (0.1, 7) 100 (0.03, 0.2) 562 (0.5) 120 (4) 85 (3) 588 (24, 0.4) 273 (75, 0.02) 128 (0.5, 2) 100 (1, 5) 1860 (1133, 27) 549 (3, 16) 509 (16, 0.7) 240 (31, 0.5) 128 (1, 1) 83 (0.3, 0.3)
1946 (745, 34) 631 (43, 3) 557 (5, 27) 178 (10, 10) 151 (5, 21) 110 (0.004, 4) 84 (0.05, 2) 62 (0.02, 2) 550 (0.2) 86 (7) 71 (1) 574 (21, 0.2) 183 (54, 0.4) 99(0.1, 1) 80(0.4, 6) 1871 (950, 35) 542 (1, 11) 496 (12, 1) 148 (20, 4) 95 (0.01, 0.4) 63 (0.1, 0.3)
1945 (756, 24) 617 (59, 6) 553 (5, 26) 140 (5, 5) 112 (1, 23) 107 (1, 8) 66 (0.4, 1) 45 (0.0002, 2) 539 (0.1) 86 (4) 54 (3) 565 (26, 0.4) 150 (32, 1) 98 (0.1, 2) 62 (0.7, 4) 1877 (783, 31) 536 (0.1, 9) 487 (12, 2) 114 (10, 5) 85 (0.8, 0.2) 52 (0.2, 0.4)
Exp. [42]
A1 1 [CO ] A1 2 [␦OsCO ] A1 3 [OsC ] A1 4 [OsX ] A1 5 [OsX ] B1 12 [␦OsCO ] B1 13 [OsX ] B2 16 [CO] B2 17 [␦OsCO ] B2 18 [OsC ] B2 19 [OsX ] B2 20 [␦XOsX ]
– – – – – – – – – – – –
2024 652 600 312 276 596 302 1899 – 533 258 130
2005 641 601 189 164 588 213 1902 – 511 – –
2001 624 599 135 108 577 160 1912 545 506 – –
a
Data in the parentheses are vibrational intensities, the first value in parentheses is infrared intensity and the second one is Raman active.
were performed with the use of Becke’s three parameters hybrid method with the Lee, Yang and Parr non-local functions [48,49]. The maximum values of the converged criterion are 0.000383 for maximum force, 0.000077 for RMS force, 0.001780 for maximum displacement and 0.000726 for RMS displacement (au. units), all geometries converged perfectly, and all optimized structure have only positive eigenvalues of the Hessian matrix, i.e. they are minima on the potential energy surface. The vibrational frequencies and intensities were computed at the same theoretical levels as that used in the geometry optimization. 3. Results and discussion 3.1. Optimized geometries The geometries of the complexes Os(CO)6 2+ , cisOs(CO)2 X4 2− , fac-Os(CO)3 X3 − and Os(CO)5 X+ were optimized under the restriction of Oh , C2v , C3v , and C4v symmetries, subsequent frequency calculations showed that these structures are indeed minima on the potential energy surface (number of imaginary frequencies is zero). The calculated bond lengths are given in Tables 1–3 and the fully optimized geometries of these complexes are shown in Fig. 1. As seen in the tables,
the calculated bond distances are dependent on the theoretical methods used. With the same basis set, the bond lengths ˚ longer than that calcalculated by B3LYP are ca. 0.033–0.047 A ˚ shorter for Os–C. For culated by RHF for C–O, 0.032–0.057 A Os–X bond distances, the bond lengths calculated by B3LYP ˚ shorter than that calculated by RHF in are ca. 0.004–0.028 A ˚ cis-Os(CO)2 X4 2− and fac-Os(CO)3 X3 − , while, 0.022–0.027 A longer in Os(CO)5 X+ . Using the same method, although SDD basis set is bigger than LanL2DZ, the calculated results are close to each other. Compared to Os(CO)6 2+ , the calculated bond distances of Os–C in the mixed carbonyl-halide complexes are shortened with halogen atoms substitution, especially, the Os–C bond that is trans to the halogen atoms. In complexes of cis-Os(CO)2 X4 2− , the bond distances of Os–X1 , ˚ shorter than which are trans to Os–C, are about 0.001–0.045 A Os–X3 . In the complexes Os(CO)5 X+ , the bond distances of Os–C at axial position, are slightly shorter than that at equatorial position, while the C–O distance at axial position, are slightly longer than that at equatorial position. For these compounds, the more halogen substituted, the shorter Os–C bond distance and the longer C–O bond distances were obtained. Although there is no structure data available for these complexes, the bonds parameter of Os(C6 H4 Cl–2)Cl(CO)(PPh3 )2
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Table 6 Calculated vibrational frequencies of fac-Os(CO)3 X3 − Method
Assignment
Os(CO)3 F3 −
Os(CO)3 Cl3 −
Os(CO)3 Br3 −
Os(CO)3 I3 −
RHF/LanL2DZ
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 6 A1 [␦XOsX ] 7 A2 [␦OsCO ] 8 A2 [␦XOsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 14 E[␦XOsC ] 15 E[␦XOsC ] 16 E[␦XOsC ]
2263 (411, 156)a 546 (146, 1) 457 (0.4, 4) 672 (65, 2) 213 (9, 1) 111 (0.01, 2) 546 125 2159 (1639, 148) 652 (25, 0.9) 566 (48, 0.2) 511 (66, 2) 435 (39, 1) 207 (1, 0.5) 133 (6, 1) 102 (0.001, 4)
2275 (703, 277) 653 (136, 5) 460 (1, 0.6) 319 (33, 7) 131 (2, 0.2) 114 (1, 5) 524 96 2200 (1203, 120) 631 (39, 4) 534 (25, 0.09) 439 (22, 0.8) 296 (33, 2) 130 (2, 0.7) 114 (0.01, 5) 98 (0.4, 0.4)
2267 (906, 344) 646 (156, 9) 462 (5, 0.6) 216 (11, 7) 121 (0.08, 2) 99 (0.02, 3) 517 84 2199 (1087, 110) 624 (45, 7) 525 (25, 0.3) 440 (14, 0.7) 194 (16, 3) 119 (0.0007, 2) 99 (0.02, 3) 72 (0.002, 1)
2254 (1179, 426) 643 (173, 15) 466 (11, 0.6) 174 (5, 7) 121 (0.3, 3) 96 (0.1, 2) 514 82 2191 (985, 99) 619 (54, 12) 522 (25, 0.7) 442 (8, 0.7) 153 (9, 5) 119 (0.5, 2) 96 (0.1, 2) 58 (0.002, 2)
RHF/SDD
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 6 A1 [␦XOsX ] 7 A2 [␦OsCO ] 8 A2 [␦XOsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 14 E[␦XOsC ] 15 E[␦XOsC ] 16 E[␦XOsC ]
2260 (409, 158) 545 (153, 1) 449 (0.1, 4) 665 (62, 2) 212 (9, 1) 109 (0.02, 2) 535 126 2159 (1592, 150) 644 (24, 0.6) 557 (51, 0.1) 510 (74, 1) 423 (33, 2) 207 (2, 0.6) 135 (6, 1) 100 (0.002, 4)
2271 (690, 240) 649 (128, 4) 455 (1, 0.8) 314 (32, 7) 132 (2, 0.2) 113 (0.8, 4) 518 100 2200 (1139, 111) 626 (38, 3) 528 (25, 0.2) 432 (21, 0.8) 289 (34, 2) 132 (1, 0.8) 114 (0.03, 4) 100 (0.3, 0.5)
2265 (897, 215) 641 (138, 5) 454 (4, 1) 214 (15, 8) 120 (0.03, 2) 85 (0.3, 3) 511 86 2200 (1009, 107) 620 (42, 6) 519 (21, 0.5) 431 (12, 0.6) 189 (20, 4) 118 (0.003, 1) 100 (0.06, 3) 75 (0.0, 1)
2254 (1179, 426) 643 (173, 15) 466 (11, 0.6) 174 (5, 7) 121 (0.3, 3) 68 (0.02, 4) 514 82 2191 (985, 99) 619 (54, 12) 522 (25, 0.7) 442 (8, 0.7) 153 (9, 5) 119 (0.5, 2) 96 (0.1, 2) 58 (0.003, 2)
B3LYP/LanL2DZ
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 6 A1 [␦XOsX ] 7 A2 [␦OsCO ] 8 A2 [␦XOsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 14 E[␦XOsC ] 15 E[␦XOsC ] 16 E[␦XOsC ]
2034 (297, 80) 537 (96, 6) 518 (6, 25) 635 (26, 2) 228 (3, 2) 102 (0.5, 5) 511 107 1925 (1262, 64) 621 (13, 0.2) 537 (44, 0.2) 510 (36, 11) 489 (11, 0.4) 212 (0.6, 1) 122 (4, 0.9) 95 (0.05, 6)
2043 (501, 182) 618 (86, 1) 509 (0.7, 7) 311 (16, 13) 127 (0.7, 0.8) 103 (0.2, 7) 487 77 1954 (1005, 78) 595 (26, 1) 509 (0.8, 7) 497 (26, 2) 285 (24, 4) 120 (0.3, 1) 102 (0.1, 7) 86 (0.2, 0.9)
2035 (621, 230) 607 (108, 3) 503 (0.003, 8) 208 (4, 9) 109 (0.03, 3) 78 (0.02, 5) 477 67 1951 (903, 84) 581 (33, 2) 504 (0.002, 8) 488 (23, 0.1) 184 (11, 4) 106 (0.003, 3) 85 (0.04, 4) 66 (0.0002, 2)
2024 (766, 290) 600 (131, 7) 499 (0.1, 7) 165 (1, 8) 106 (0.2, 3) 63 (0.05, 5) 468 66 1946 (801, 90) 569 (42, 5) 500 (0.1, 7) 482 (21, 0.7) 142 (6, 5) 108 (0.1, 4) 82 (0.3, 2) 53 (0.008, 3)
B3LYP/SDD
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 6 A1 [␦XOsX ] 7 A2 [␦OsCO ] 8 A2 [␦XOsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 14 E[␦XOsC ]
2031 (296, 77) 531 (55, 0.007) 510 (9, 24) 631 (24, 1) 227 (2, 2) 101 (0.5, 5) 502 108 1924 (1256, 67) 616 (13, 0.09) 531 (55, 0.01) 507 (42, 10) 483 (0.9, 0.4) 212 (0.6, 1)
2040 (489, 149) 614 (78, 0.6) 500 (5, 5) 309 (15, 13) 130 (0.7, 0.7) 103 (0.06, 6) 480 80 1951 (976, 77) 590 (26, 0.5) 500 (5, 5) 490 (24, 3) 283 (24, 3) 124 (0.2, 1)
2033 (628, 131) 603 (94, 1) 492 (0.2, 7) 207 (6, 12) 108 (0.0, 2) 83 (0.04, 4) 471 68 1949 (855, 92) 580 (29, 2) 492 (0.3, 7) 483 (20, 0.09) 180 (14, 5) 104 (0.0, 2)
2022 (764, 127) 595 (121, 3) 488 (0.2, 5) 164 (2, 9) 106 (0.04, 5) 65 (0.003, 4) 461 67 1945 (734, 93) 566 (40, 3) 489 (0.2, 5) 475 (17, 1) 140 (7, 6) 104 (0.3, 3)
Z. Jianying et al. / Spectrochimica Acta Part A 65 (2006) 501–510
507
Table 6 (Continued ) Method
Exp. [42]
a
Assignment
Os(CO)3 F3 −
Os(CO)3 Cl3 −
Os(CO)3 Br3 −
Os(CO)3 I3 −
15 E[␦XOsC ] 16 E[␦XOsC ]
127 (5, 0.9) 92 (0.06, 6)
102 (0.2, 6) 88 (0.1, 1)
88 (0.007, 5) 69 (0.004, 2)
84 (0.2, 2) 53 (0.002, 3)
1 A1 [CO ] 2 A1 [␦OsCO ] 3 A1 [OsC ] 4 A1 [OsX ] 5 A1 [␦COsC ] 9 E[CO ] 10 E[␦OsCO ] 11 E[␦OsCO ] 12 E[OsC ] 13 E[OsX ] 15 E[␦XOsC ]
– – – – – – – – – – –
2125 598 470 322 136 2040 624 499 468 281 105
2120 595 479 217 121 2040 613 494 465 200 101
2110 580 470 178 – 2040 597 488 462 159 –
Data in the parentheses are vibrational intensities, the first value in parentheses is infrared intensity and the second one is Raman active.
and (I)[Os(CO)3 (CNBu+ )]3 Mn(CO)5 can be used to compare the Os–C, Os–Cl and Os–I bond distance, in which Os–C bond ˚ Os–Cl is 2.466 A ˚ and Os–I is 2.777 A ˚ distances is 1.850 A, [50,51], therefore, our calculated bond distances are overestimated at all levels in some extent. Considering that the optimized geometries are ionic compounds without countercations involved and electron correction deficiencies of basis sets employed, it is estimated that the deviations of calculated geometry parameters from the observed ones are quite substantial. In general, longer bond lengths will result in lower vibrational frequencies and higher vibrational intensities. However, as seen below, the calculated results are not only dependent on the optimized geometries, but also on the theoretical method used. 3.2. Vibrational frequencies Vibrational analysis for the Oh symmetric complex Os(CO)6 2+ indicates that the complex has 33 fundamental vibrations (2A1g , 2Eg , T1g , 3T1u , 2T2g , 2T2u ), in which T1u are only infrared active, A1g , Eg and T2g are only Raman-active and T1g , T2u are inactive. The complexes of cis-Os(CO)2 X4 2− belong to C2v symmetry, 21 fundamental vibrational modes can be reduced to vib = 8A1 + 3A2 + 4B1 + 6B2 , in which, A1 , B1 and B2 are both infrared and Raman active, A2 frequencies are Raman active only. The calculated vibrational frequencies and intensities of these molecules are summarized in Tables 4 and 5, together with available experimental values. The assignment of the calculated vibrational fundamental frequencies is based on the symmetry, experimental values, vibrational intensities and calculated normal vibrational modes. Considering the C–O stretching vibration modes (1 A1g , 3 Eg and 6 T1u in Os(CO)6 2+ ; 1 A1 and 16 B2 in cisOs(CO)2 X4 2− ), the theoretical methods, rather than basis sets and displacement of halogens, dominate the accuracy of the calculated values. The frequencies calculated at B3LYP level give the results 31–84 cm−1 lower than the experimental values. However, the frequencies calculated at RHF levels are 145–215 cm−1 higher than the measured ones. Therefore, these results indicate that the B3LYP method is more suitable for calculation of the C–O stretching vibrational frequencies for
these complexes. The values obtained with LanL2DZ and SDD basis sets are close to each other. With varying from Cl to I, the calculated C–O frequencies slightly changed, this trend is consistent with that observed in the experiments. For 1 A1g of cis-Os(CO)2 X2 − , the vibrational frequencies are significantly lower than that in the complex of Os(CO)6 2+ , this result indicates that halogen substitution causes change in charge distribution and force constants of C–O bonds. In the far-infrared region, the experimental vibrational frequencies of Os(CO)6 2+ were well assignment by Wang et al. [52]. However, the assignment of cis-Os(CO)2 X4 2− are incompletely. Cleare and Griffith [42] assigned the experimental vibrational frequencies of ca. 650 cm−1 to A1 3 Os–C stretching mode and that of ca. 600 cm−1 to A1 2 Os–C–O bending vibration. However, according to our calculations, we’d better assign the experimental vibrational frequencies of 652, 641 and 624 cm−1 to A1 2 Os–C–O bending mode and that of 600, 601 and 599 cm−1 to Os–C stretching vibrational mode for cis-Os(CO)2 Cl4 2− , cis-Os(CO)2 Br4 2− and cis-Os(CO)2 I4 2− , respectively. With this assignments, the frequencies calculated at B3LYP level with two basis sets are in good agreement with the experimental ones, little better values are obtained at B3LYP/SDD level. With this method, the deviations of calculated data from experimental values are less than 9% for the Os–X stretching vibrational modes, and less than 8% for Os–C stretching vibrational modes for Os(CO)6 2+ and cisOs(CO)2 X4 2+ . With halogen vary from F to I, the vibrational frequencies of Os–C stretching mode and Os–C–N bending mode slightly decreased. The vibrational frequencies of [Os(CO)6 ]2+ has been calculated by Thiel and co-workers with BP86/ECP2 [29], our calculation is very close to the results. Since there is no scale factor used in these calculations for comparison with experimental data, it is reasonable to believe that B3LYP/SDD calculation for the vibrational frequencies of Os(CO)6 2+ and cis-Os(CO)2 X4 2− provides reliable data for the vibrational modes and it is believable for further calculations of vibrational frequencies. In C3v symmetry fac-Os(CO)3 X3 -type complexes, the CO groups are trans to the halogen atoms. Twenty-four fundamental vibrational modes are reduced to vib = 6A1 + 2A2 + 8E, in
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Table 7 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of Os(CO)5X+ Method
Assignment
Os(CO)5 F+
Os(CO)5 Cl+
Os(CO)5 Br+
Os(CO)5 I+
RHF/LanL2DZ
1 A1 [CO ] 2 A1 [CO ] 3 A1 [␦OsCO ] 4 A1 [OsC ] 5 A1 [OsC ] 6 A1 [OsX ] 7 A1 [␦COsC ] 8 A2 [OsC ] 9 B1 [␦OsCO ] 10 B1 [␦COsC ] 11 B2 [CO ] 12 B2 [␦OsCO ] 13 B2 [␦OsCO ] 14 B2 [␦COsC ] 15 E[CO ] 16 E[␦OsCO ] 17 E[␦OsCO ] 18 E[␦OsCO ] 19 E[OsC ] 20 E[␦COsX ] 21 E[␦COsX ] 22 E[␦COsC ]
2431 (0.1, 225)a 2332 (693, 136) 605 (145, 2) 395 (13, 1) 379 (4, 0.4) 575 (145, 2) 112 (0.005, 0.4) 373 523 (0, 5) 109 (0, 6) 2397 (222) 549 (0, 0.01) 370 (0, 2) 80 (0, 0.2) 2378 (923, 13) 593 (99, 0.3) 557 (0.001, 2) 437 (0.3, 1) 324 (22, 1) 159 (7, 0.05) 113 (0.1, 1) 97 (0.03, 3)
2423 (26, 240) 2336 (668, 167) 607 (143, 1) 405 (24,2) 390 (1, 9) 357 (24, 8) 120 (0.1, 0.1) 379 530 (0, 5) 111 (0, 6) 2387 (213) 553 (0, 0.2) 380 (0, 1) 88 (0, 0.03) 2373 (949, 2) 597 (102, 0.5) 555 (3, 4) 438 (1, 0.2) 340 (23, 0.2) 126 (2, 0.04) 108 (1, 5) 99 (0.4, 0.7)
2417 (64, 250) 2336 (658, 190) 610 (61, 2) 399 (11, 1) 393 (0.1, 1) 241 (7, 9) 121 (0.3, 0.01) 381 532 (0, 5) 111 (0, 6) 2381 (216) 553 (0, 0.5) 384 (0, 1) 91 (0, 0.01) 2367 (984, 0.05) 598 (101, 0.4) 552 (6, 6) 438 (2, 0.3) 345 (24, 0.03) 121 (0.4, 0.3) 103 (0.1, 4) 86 (1, 0.5)
2408 (138, 260) 2334 (643, 222) 613 (184, 5) 398 (10, 0.4) 394 (4, 2) 190 (3, 11) 122 (0.7, 0.4) 383 534 (0, 4) 111 (0, 6) 2372 (223) 553 (0, 1) 389 (0, 1) 93 (0, 0.0002) 2358 (1039, 2) 600 (100, 0.4) 550 (9, 8) 438 (4, 0.3) 351 (27, 0.04) 120 (0.2, 0.5) 104 (0.04, 4) 79 (0.4, 0.5)
RHF/SDD
1 A1 [CO ] 2 A1 [CO ] 3 A1 [␦OsCO ] 4 A1 [OsC ] 5 A1 [OsC ] 6 A1 [OsX ] 7 A1 [␦COsC ] 8 A2 [OsC ] 9 B1 [␦OsCO ] 10 B1 [␦COsC ] 11 B2 [CO ] 12 B2 [␦OsCO ] 13 B2 [␦OsCO ] 14 B2 [␦COsC ] 15 E[CO ] 16 E[␦OsCO ] 17 E[␦OsCO ] 18 E[␦OsCO ] 19 E[OsC ] 20 E[␦COsX ] 21 E[␦COsX ] 22 E[␦COsC ]
2425 (0.01, 226) 2326 (680, 136) 602 (5, 1) 387 (12, 1) 375 (2, 0.5) 575 (183, 2) 110 (0.01, 0.4) 363 538 (0, 0.04) 106 (0, 0, 5) 2389 (0, 0, 218) 514 (0, 4) 371 (0, 2) 79 (0, 0.1) 2373 (890, 11) 585 (94, 0.4) 551 (0.3, 2) 428 (0.2, 0.7) 307 (18, 1) 160 (7, 0.1) 110 (0.03, 1) 95 (0.03, 3)
2418 (24, 231) 2332 (661, 167) 595 (140, 1) 399 (3, 2) 383 (1, 1) 349 (24, 7) 116 (0.03, 0.1) 368 540 (0, 0.2) 108 (0, 5) 2385 (0, 201) 519 (0, 4) 379 (0, 1) 86 (0, 0.04) 2369 (898, 2) 587 (99, 0.5) 548 (1, 3) 428 (0.6, 0.3) 318 (19, 0.2) 125 (3, 0.1) 107 (0.7, 4) 96 (0.2, 1)
2411 (56, 225) 2329 (654, 193) 599 (153, 1) 392 (8, 1) 384 (0.4, 1) 237 (10, 9) 117 (0.2, 0.1) 370 541 (0, 0. 3) 108 (0, 5) 2377 (0, 202) 521 (0, 4) 381 (0, 1) 89 (0, 0.02) 2361 (925, 0.01) 587 (96, 0.5) 545 (4, 5) 428 (2, 0.3) 322 (20, 0.02) 118 (0.6, 0.2) 101 (0.1, 4) 87 (0.8, 0.4)
2403 (122, 220) 2328 (639, 225) 601 (180) 390 (10, 1) 388 (2, 2) 187 (4, 10) 119 (0.6, 0.6) 372 539 (0, 1) 108 (0, 5) 2370 (0, 204) 524 (0, 4) 386 (0, 0.6) 92 (0, 0.01) 2354 (970, 2) 589 (94, 0.5) 542 (8, 6) 427 (3, 0.3) 327 (23, 0.02) 117 (0.4, 0.4) 101 (0.1, 4) 79 (0.5, 0.5)
B3LYP/LanL2DZ
1 A1 [CO ] 2 A1 [CO ] 3 A1 [␦OsCO ] 4 A1 [OsC ] 5 A1 [OsC ] 6 A1 [OsX ] 7 A1 [␦COsC ] 8 A2 [OsC ] 9 B1 [␦OsCO ] 10 B1 [␦COsC ] 11 B2 [CO ] 12 B2 [␦OsCO ] 13 B2 [␦OsCO ] 14 B2 [␦COsC ] 15 E[CO ] 16 E[␦OsCO ] 17 E[␦OsCO ] 18 E[␦OsCO ]
2184 (0.02, 223) 2063 (608, 137) 593 (86, 1) 452 (2, 14) 434 (16, 3) 532 (23, 5) 100 (0.1, 0.5) 364 500 (0, 1) 104 (0, 9) 2129 (0, 315) 538 (0, 0.2) 418 (0, 0.2) 70 (0, 0.2) 2101 (894, 18) 584 (70, 0.03) 541 (0.3, 0.4) 421 (0.1, 0.3)
2177 (16, 225) 2067 (589, 170) 591 (110, 0.5) 456 (3, 13) 443 (5, 4) 332 (9, 10) 108 (0.5, 0.1) 367 504 (0, 1) 105 (0, 9) 2124 (0, 286) 526 (0, 0.03) 426 (0, 0.4) 74 (0, 0.05) 2099 (883, 6) 583 (72, 0.04) 532 (4, 2) 414 (0.1, 0.4)
2170 (39, 228) 2065 (585, 201) 590 (123, 0.6) 455 (3, 15) 442 (6, 2) 220 (3, 7) 110 (0.7, 0.06) 368 504 (0, 0.8) 105 (0, 9) 2118 (0, 278) 519 (0, 0.3) 428 (0, 0.6) 77 (0, 0.02) 2094 (901, 2) 583 (70, 0.02) 526 (7, 3) 410 (0.7, 0.8)
2161 (86, 237) 2063 (584, 249) 591 (140, 1) 455 (2, 18) 439 (8, 1) 172 (1, 6) 111 (1, 0.4) 370 507 (0, 0.6) 105 (0, 9) 2109 (0, 270) 513 (0, 1) 433 (0, 1) 80 (0, 0.01) 2085 (932, 0.02) 584 (68, 0.002) 521 (9, 5) 409 (2, 2)
Z. Jianying et al. / Spectrochimica Acta Part A 65 (2006) 501–510
509
Table 7 (Continued ) Method
B3LYP/SDD
a
Assignment
Os(CO)5 F+
Os(CO)5 Cl+
Os(CO)5 Br+
Os(CO)5 I+
19 20 21 22
346 (50, 1) 145 (0.7, 0.03) 104 (0.02, 3) 92 (0.2, 4)
365 (57, 1) 114 (0.2, 0.3) 95 (0.03, 7) 89 (0.5, 0.1)
370 (46, 1) 111 (0.03, 1) 95 (0.01, 5) 71 (0.4, 0.9)
376 (45, 1) 110 (0.01, 1) 96 (0.0004, 4) 65 (0.2, 0.5)
2177 (0.03, 225) 2057 (614, 138) 585 (82, 0.8) 448 (2, 13) 432 (14, 4) 544 (46, 6) 99 (0.1, 0.5) 352 491 (0, 0.7) 101 (0, 9) 2125 (0, 318) 528 (0, 0.2) 418 (0, 0.2) 68 (0, 0.2) 2096 (883, 18) 576 (70, 0.03) 537 (0.02, 0.3) 413 (0.1, 0.2) 337 (47, 1) 150 (1, 0.1) 102 (0.001, 3) 90 (0.2, 3)
2170 (15, 219) 2061 (594, 172) 581 (110, 0.6) 451 (3, 12) 437 (4, 5) 327 (9, 10) 105 (0.3, 0.1) 355 495 (0, 0.6) 102 (0, 9) 2120 (0, 281) 515 (0, 0.005) 424 (0, 0.4) 73 (0, 0.1) 2094 (861, 6) 575 (72, 0.03) 527 (3, 1) 404 (0.3, 0.5) 352 (43, 1) 114 (0.4, 0.1) 95 (0.1, 7) 88 (0.3, 0.3)
2163 (36, 210) 2058 (593, 206) 582 (120, 0.7) 448 (2, 16) 436 (6, 3) 218 (4, 7) 107 (0.6, 0.1) 356 496 (0, 0.7) 102 (0, 9) 2113 (0, 270) 510 (0, 0.1) 427 (0, 0.7) 75 (0, 0.04) 2087 (875, 2) 575 (69, 0.02) 522 (5, 2) 402 (0.7, 0.8) 356 (43, 1) 109 (0.1, 1) 92 (0.0001, 5) 73 (0.4, 0.8)
2155 (79, 206) 2056 (593, 252) 580 (142, 1) 449 (1, 20) 434 (7, 1) 171 (1, 6) 109 (1, 0.6) 359 499 (0, 0.6) 103 (0, 8) 2105 (0, 257) 501 (0, 0.6) 430 (0, 1) 78 (0, 0.02) 2079 (897, 0.04) 575 (67, 0.002) 515 (8, 4) 398 (1, 2) 362 (41, 1) 108 (0.1, 1) 93 (0.004, 4) 66 (0.3, 0.5)
E[OsC ] E[␦COsX ] E[␦COsX ] E[␦COsC ]
1 A1 [CO ] 2 A1 [CO ] 3 A1 [␦OsCO ] 4 A1 [OsC ] 5 A1 [OsC ] 6 A1 [OsX ] 7 A1 [␦COsC ] 8 A2 [OsC ] 9 B1 [␦OsCO ] 10 B1 [␦COsC ] 11 B2 [CO ] 12 B2 [␦OsCO ] 13 B2 [␦OsCO ] 14 B2 [␦COsC ] 15 E[CO ] 16 E[␦OsCO ] 17 E[␦OsCO ] 18 E[␦OsCO ] 19 E[OsC ] 20 E[␦COsX ] 21 E[␦COsX ] 22 E[␦COsC ]
Data in the parentheses are vibrational intensities, the first value in parentheses is infrared intensity and the second one is Raman active.
which A1 , and E modes are both infrared active and Raman active, the calculated vibrational frequencies and intensities of the complexes are listed in Table 6. Similar to the calculated bond distances increased from F to I, the calculated vibrational frequencies of Os–X are significantly dependent on substitution of halogen atoms. Using B3LYP/SDD method, 467 and 343 cm−1 decreased for the Os–X stretching vibrational modes of 4 A1 and 13 E, respectively, when halogen changes from F to I. The calculated 4 Os–X stretching vibrational frequencies of A1 symmetry in fac-Os(CO)3 X3 − are 24–135 cm−1 higher than that in the cis-Os(CO)2 X4 2− , while the calculated 13 Os–X stretching vibrational frequencies of E symmetry in fac-Os(CO)3 X3 − are 32–43 cm−1 higher than those in cis-Os(CO)2 X4 2− B2 symmetry 19 . Similar trends can be found in other methods. The complexes of Os(CO)5 X+ belong to C4v symmetry. There are 30 fundamental vibrations reduced to vib = 7A1 + A2 + 2B1 + 4B2 + 8E, in which, A1 and E are both infrared and Raman active, B1 and B2 are Raman active only. In these complexes, the CO group arrange in two positions, one of them is trans to the halogen atom and the others are neighbor to the halogen atom. The calculated vibrational frequencies and intensities of the complexes are listed in Table 7. For the C–O that are neighbor to halogen atoms, the theoretical methods, rather than basis sets and displacement of halogens, dominate the calculated values of Os–C stretching vibrational modes, there is no significant change with varying from F to I. However, when CO group and halogen atom are in the trans position, the Os–C stretching and C–Os–C bending are not only dependent on the theoretical methods but also on the substituted halogen atoms.
3.3. Vibrational intensities The intensity of antisymmetric vibrations may be used as a measurement of the extent of bonding in this type of complexes [53]. As shown in parentheses of Tables 4–7, the calculated intensities are mainly dependent on the theoretical methods, rather than basis sets. In these complexes, the vibrational intensities calculated at B3LYP level correctly give relative tendency of the major intensities in the experimental vibrational spectra. For the complexes studied here, the IR vibrational intensities of A1 C–O stretching vibrational modes increase significantly from Cl to I, indicating that the C–O -bond strength increases in the order (C–O)Cl < (C–O)Br < (C–O)I. The heavier halogens donate their -bonding electrons more to the Os atom because of their smaller electronegativity, therefore, a tendency for back of -bonding electrons to the carbonal ligand would be expected. 4. Conclusion This investigation indicates that B3LYP method is superior to RHF method for the calculation of C–O stretching vibrational mode and far-infrared frequencies in heavy atom containing mixed carbonyl-halide Os(II) complexes, with both basis sets concerned. For a given method, the calculated data are slightly improved by SDD basis set. In infrared frequency region, the C–O stretching vibrational frequencies calculated at B3LYP level with two basis sets are in good agreement with the observed values with deviations less than 5%. In the far-infrared region,
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the B3LYP/SDD method achieved the best results with deviations less than 9% for Os–X stretching and less than 8% for Os–C stretching vibrational frequencies. These deviations are quite smooth for a given type of vibration. The C–O stretching vibrational frequencies and Os–X, Os–C stretching frequencies and the OsCN bending vibrational frequencies calculated at B3LYP/SDD level, are accurate enough with the deviations in the same order as anharmonicity corrections and effect from solvent or matrix or crystal. Therefore, this study confirms again that the theoretical calculation of vibrational frequencies for metal complexes is quite useful for the vibrational assignment and for predicting new vibrational frequencies. Acknowledgments This work was supported by the Natural Science Foundation of Jiangsu Educational Department (Nos. 04KJB 150015). References [1] L. Mond, C. Langer, F.J. Quincke, Chem. Soc. (1890) 749. [2] H. Werner, Angew. Chem. 102 (1990) 1109; H. Werner, Angew. Chem., Int. Ed. Engl. 29 (1990) 1077. [3] J.E. Ellis, Adv. Organomet. Chem. 31 (1990) 1. [4] E.P. Kundig, M. Moskovits, G.A. Ozin, Angew. Chem., Int. Ed. Engl. 14 (1975) 292. [5] G.A. Ozin, Acc. Chem. Res. 10 (1977) 21. [6] P.K. Hurlburt, J.J. Rack, J.S. Luck, S.F. Dec, J.D. Webb, O.P. Anderson, S.H. Strauss, J. Am. Chem. Soc. 116 (1994) 10003. [7] E.I. Solomon, P.M. Jones, J.A. May, Chem. Rev. 93 (1993) 2623. [8] A. Sen, Acc. Chem. Res. 26 (1993) 303. [9] K.C. Waugh, Catal. Today 15 (1992) 51. [10] M.A. Vannice, Catal. Today 12 (1992) 255. [11] L. Guczi (Ed.), Studies in Surface Science and Catalysis; New Trends in CO Activation 64, Elsevier, Amsterdam, 1991. [12] G. Henrici-Oliv´e, S. Oliv´e, The Chemistry of the Catalyzed Hydrogenation of Carbon Monoxide, Springer-Verlag, Berlin, 1983. [13] P.C. Ford (Ed.), Catalytic Activation of Carbon Monoxide; ACS Symposium Series 152, American Chemical Society, Washington, DC, 1981. [14] A.W. Ehlers, S. Dapprich, S.F. Vyboishchikov, G. Frenking, Organometallics 15 (1996) 105. [15] M.S. Dewar, Bull. Soc. Chim. Fr. 18 (1951) C71. [16] J. Chatt, L.A. Duncanson, J. Chem. Soc. (1953) 2939. [17] R. Hoffmann, M.M.L. Chen, D.L. Thorn, Inorg. Chem. 16 (1977) 503.
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