Ab initio and DFT studies on vibrational spectra of some mixed carbonyl-halide complexes of ruthenium(II)

Ab initio and DFT studies on vibrational spectra of some mixed carbonyl-halide complexes of ruthenium(II)

Spectrochimica Acta Part A 61 (2005) 697–706 Ab initio and DFT studies on vibrational spectra of some mixed carbonyl-halide complexes of ruthenium(II...

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Spectrochimica Acta Part A 61 (2005) 697–706

Ab initio and DFT studies on vibrational spectra of some mixed carbonyl-halide complexes of ruthenium(II) Yu Zhanga,∗ , Jianying Zhaoa , Guodong Tanga , Longgen Zhub,∗∗ a

Chemistry Department, Huai Yin Teachers College, Huai An 223001, Jiangsu, People’s Republic of China State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093, Jiangsu, People’s Republic of China

b

Received 6 March 2004; accepted 28 April 2004

Abstract The vibrational spectra of Ru(CO)6 2+ and some of its mixed carbonyl-halide complexes, cis-Ru(CO)2 X4 2− , fac-Ru(CO)3 X3 − and Ru(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 Ru(CO)6 2+ , cis-Ru(CO)2 X4 2− and fac-Ru(CO)3 X3 − are evaluated via comparison with the experimental values. In the 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 8% for Ru–X stretching and less than 2% for Ru–C stretching vibrational frequencies. The vibrational frequencies for Ru(CO)5 X+ that have not been experimentally reported were predicted. © 2004 Elsevier B.V. All rights reserved. Keywords: Vibrational frequencies; Theoretical calculation; Mixed carbonyl-halide complexes of Ru(II)

1. Introduction Transition metal carbonyl complexes, which have formed a large and important class of inorganic compounds, have been of interests to experimental and theoretical chemists for a long time [1,2]. The nature of the bonds between transition metals and carbon monoxides were well established. The synergic bonding model due to Dewar [3] and Chatt and Duncanson [4] has a central role in organometallic chemistry. Quantum chemical methods, such as ab initio Hartree–Fock (HF), second-order Møller–Plesset (MP2) and density functional theory (DFT), have been shown to be an efficient and accurate methods for the calculation of transition metal compounds. These quantum chemical methods are able to predict electronic structure, bond characteristics, NMR chemical shift, etc. The applications of theoretical method to ∗ ∗∗

Corresponding author. Tel.: +86 5173511083; fax: +86 5173942349. E-mail address: [email protected] (Y. Zhang). Co-corresponding author.

1386-1425/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.saa.2004.04.025

predict the vibrational spectra have recently been extended to transition metal complexes. There are many calculations of vibrational spectra for transition metal complexes reported recently, such as, transition metal carbonyl complexes [5–11], ethylene complexes M(C2 H4 ) (M = Cu, Ag and Ru) [12] and [PdCl3 (C2 X4 )] [13], Agx (NO)y clusters [14], metal–polyarsenic complexes MAs8 n (M = V, Nb, Ta, Cr, Mo, W, Mn, Tc and Re) [15], Pd(II) and Pt(II) complexes [16–18]. We recently reported the theoretical calculation of vibrational spectra for mixed cyanide-halide complexes of palladium(IV) and platinum(IV) complexes [19]. Some of the vibrational frequencies of mixed carbonylhalide complexes were experimentally investigated by Cleare and Griffith [20], 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-

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halide complexes of Ru(II), in order to identify 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. 2. Calculations Geometry optimization is one of the most important steps in the theoretical calculations of vibrational spectra. This procedure proceeds in two steps—firstly the geometry was constructed by MM+ molecular dynamics from HyperChem 6.0 package [21], and secondly, optimized by RHF and DFT levels of theory with LanL2DZ (Los Alamos ECP plus double-zeta) [22,23] and SDD (Stuttgart/Dresden effective core potential) [24] basis sets using Gaussian 98W program package [25]. DFT calculations were performed with the use of Becke’s three parameter hybrid method with the Lee, Yang and Parr non-local functions [26,27]. 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 (a.u.), all geometries converged perfectly. 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 fully optimized geometries of Ru(CO)6 2+ , cisRu(CO)2 X4 2− , fac-Ru(CO)3 X3 − and Ru(CO)5 X+ (X = F, Cl, Br and I) are shown in Fig. 1. The calculated bond lengths and are given in Tables 1–3. The complex Ru(CO)6 2+ has a octahedron configuration with Oh symmetry, while the complexes cis-Ru(CO)2 X4 2− , fac-Ru(CO)3 X3 − and Ru(CO)5 X+ are tetragonal–bipyramidal structure. As seen in the tables, the calculated bond distances are dependent on the theoretical methods used. With the same basis set, the bond  lengths calculated by B3LYP are ca. 0.03–0.05 Alonger than that calculated by RHF for C–O and 0.004–0.17 A shorter for Ru–C. For Ru–X bond distances, the bond lengths calculated  by B3LYP are ca. 0.02–0.10 A shorter than that calculated by RHF in cis-Ru(CO)2 X4 2− and fac-Ru(CO)3 X3 − , while, about 0.03 A longer in Ru(CO)5 X+ . Using the same method, SDD basis set, that is bigger than LanL2DZ, makes the Ru–C and Ru–X bond distances slightly shortened, the  maximum deviations are 0.051 A . Compared to Ru(CO)6 2+ , the calculated bond distances of Ru–C in the mixed carbonyl-halide complexes are shortened with halogen atoms substitution, especially, the Ru–C bond that is trans to the halogen atoms. In complexes of cis-Ru(CO)2 X4 2− , the bond distances of Ru–X1, which are trans to Ru–C are  about 0.003–0.041 A shorter than Ru–X3. In the complex

Fig. 1. Optimized geometries of (a) Ru(CO)6 2+ , (b) cis-Ru(CO)2 X4 2− , (c) fac-Ru(CO)3 X3 − , (d) Ru(CO)5 X+ .

Ru(CO)5 X+ , the bond distances of Ru–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 Ru–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 [crypt221-Na]2 [H2 Ru4 (CO)12 ] can be used to compare the Ru–C and the C–O bond distance, in  which the Ru–C is 1.855–1.917 A and the C–O distances  1.130–1.170 A [28], the results of our calculations are close to the experimental values. 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 Ru(CO)6 2+ indicates that the complex has thirty-three fundamental vibrations (2A1g , 2Eg , T1g , 3T1u , 2T2g , 2T2u ), in

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Table 1 ˚ Optimized bond lengths of Ru(CO)6 2+ and cis-Ru(CO)2 X4 2− (A) Method

Bond length

Ru(CO)6 2+

Ru(CO)2 F4 2−

Ru(CO)2 Cl4 2−

Ru(CO)2 Br4 2−

Ru(CO)2 I4 2−

RHF/LanL2DZ

RRu–C RC–O RRu–X1 RRu–X3

2.150 1.116 – –

1.992 1.147 2.095 2.137

2.025 1.139 2.588 2.633

2.030 1.138 2.759 2.803

2.028 1.138 2.956 2.987

RHF/SDD

RRu–C RC–O RRu–X1 RRu–X3

2.120 1.117 – –

1.941 1.150 2.081 2.114

1.974 1.141 2.569 2.602

1.982 1.139 2.717 2.752

1.981 1.138 2.930 2.953

B3LYP/LanL2DZ

RRu–C RC–O RRu–X1 RRu–X3

2.044 1.149 – –

1.856 1.201 2.046 2.080

1.859 1.189 2.556 2.552

1.863 1.188 2.729 2.713

1.867 1.188 2.922 2.887

B3LYP/SDD

RRu–C RC–O RRu–X1 RRu–X3

2.029 1.149 – –

1.839 1.202 2.046 2.066

1.843 1.191 2.533 2.522

1.849 1.188 2.693 2.670

1.853 1.188 2.899 2.860

Table 2  Optimized bond lengths of fac-Ru(CO)3 X3 − (A ) Method

Bond length

Ru(CO)3 F3 −

Ru(CO)3 Cl3 −

Ru(CO)3 Br3 −

Ru(CO)3 I3 −

RHF/LanL2DZ

Ru–X Ru–C C–O

2.057 2.043 1.135

2.536 2.036 1.133

2.697 2.033 1.134

2.880 2.028 1.134

RHF/SDD

Ru–X Ru–C C–O

2.047 2.000 1.137

2.516 1.994 1.135

2.656 1.993 1.134

2.862 1.988 1.135

B3LYP/LanL2DZ

Ru–X Ru–C C–O

2.027 1.910 1.177

2.514 1.906 1.175

2.677 1.908 1.175

2.862 1.910 1.177

B3LYP/SDD

Ru–X Ru–C C–O

2.022 1.896 1.179

2.491 1.892 1.176

2.641 1.894 1.176

2.841 1.895 1.177

Table 3  Optimized bond lengths of Ru(CO)5 X+ (A ) Method

Bond length

Ru(CO)5 X+

Ru(CO)5 X+

Ru(CO)5 X+

Ru(CO)5 X+

RHF/LanL2DZ

RRu–C RC–O RRu–X

2.121, 2.128 1.121, 1.123 1.983

2.108, 2.110 1.122, 1.121 2.438

2.108, 2.106 1.123, 1.121 2.592

2.100, 2.110 1.122, 1.123 2.772

RHF/SDD

RRu–C RC–O RRu–X

2.093, 2.077 1.121, 1.123 1.986

2.086, 2.059 1.121, 1.123 2.423

2.081, 2.060 1.122, 1.123 2.563

2.074, 2.059 1.123, 1.123 2.766

B3LYP/LanL2DZ

RRu–C RC–O RRu–X

2.094, 1.982 1.153, 1.159 2.019

2.010, 1.976 1.154, 1.159 2.465

2.009, 1.979 1.155, 1.159 2.621

2.006, 1.983 1.156, 1.160 2.800

B3LYP/SDD

RRu–C RC–O RRu–X

2.004, 1.959 1.154, 1.161 2.016

1.999, 1.956 1.155, 1.160 2.454

1.997, 1.959 1.155, 1.160 2.593

1.994, 1.962 1.157, 1.160 2.790

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Table 4 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of Ru(CO)6 2+ Assignment A1g ν1 [CO] A1g ν2 [RuC] Eg ν3 [CO] Eg ν4 [RuC] T1g ν5 [δRuCO] T1u ν6 [CO] T1u ν7 [␦RuCO] T1u ν8 [RuC] T1u ν9 [CRuC] T2g ν10 [RuCO] T2g ν11 [CRuC] T2u ν12 [RuCO] T2u ν13 [CRuC]

RHF

B3LYP

Experimental [30]

LanL2DZ

SDD

LanL2DZ

SDD

2460 (175) 278 (0.01) 2442 (92) 289 (0.2) 320 2440 (367) 520 (54) 296 (1) 115 (1) 449 (5) 95 (4) 466 84

2458 (190) 294 (0.5) 2438 (108) 308 (0.1) 323 2433 (413) 535 (74) 305 (0.1) 117 (1) 464 (4) 97 (4) 478 84

2202 (222) 380 (9) 2163 (228) 361 (0.04) 333 2146 (418) 561 (83) 330 (11) 117 (0.2) 463 (2) 98 (7) 490 81

2204 (222,0) 392 (11) 2163 (241) 378 (0.01) 332 2144 (468) 567 (99) 342 (14) 116 (0.3) 471 (1) 99 (7) 492 80

which T1u are only infrared active, A1g , Eg and T2g are only Raman-active and T1g , T2u are inactive. The complexes of cis-Ru(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 (ν1 A1g , ν3 Eg and T1u in Ru(CO)6 2+ ; ν1 A1 and ν16 B2 in cisRu(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 50–87 cm−1 lower than the experimental values. However, the frequencies calculated at RHF levels are 204–300 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 ν1 A1g of cis-Ru(CO)2 X2 − , the vibrational frequencies are significantly lower than that in the complex of Ru(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 Ru(CO)6 2+ were well assignment by Wang et al. [29]. However, the assignment of cis-Ru(CO)2 X4 2− are uncompletely. Cleare and Griffith [20] assigned the experimental vibrational frequencies of ca. 500 cm−1 to A1 ν3 Ru–C stretching mode and that of ca. 570 cm−1 to A1 ν2 RuCN bending vibration. However, according our calculations, we would better assign the experimental vibrational frequencies of 642, 631 and 613 cm−1 to A1 ν2 RuCN

2254 – 2222 382 – 2219 557 336 – – 131 – –

stretching mode in cis-Ru(CO)2 Cl4 2− cis-Ru(CO)2 Br4 2− cis-Ru(CO)2 I4 2− , respectively, and that of 541 and 535 cm−1 to Ru–C stretching vibrational mode for cis-Ru(CO)2 Cl4 2− and cis-Ru(CO)2 Br4 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 8% for the Ru–X stretching vibrational modes, and less than 2% for Ru–C stretching vibrational modes for Ru(CO)6 2+ and cis-Ru(CO)2 X4 2+ . With halogen vary from F to I, the vibrational frequencies of Ru–C stretching mode and Ru–C–N bending mode slightly decreased. The results obtained at RHF level are significantly lower than those calculated at B3LYP level, and the larger deviations are achieved. It should be emphasized that there is no scale factor used in these calculations for comparison with experimental data. Therefore, it is reasonable to believe that B3LYP/SDD calculation for the vibrational frequencies of Ru(CO)6 2+ and cis-Ru(CO)2 X4 2− provides reliable data for the vibrational modes. It is believable for further calculations of vibrational frequencies The complexes of fac-Ru(CO)3 X3 − type possesses C3v symmetry, the CO groups are trans to the halogen atoms. Twenty-four fundamental vibrational modes are reduced to vib = 6A1 + 2A2 + 8E, in 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 Ru–X are significantly dependent on substitution of halogen atoms. Using B3LYP/SDD method, 454 and 301 cm−1 decreased for the Ru–X stretching vibrational modes of ν4 A1 and ν13 E, respectively, when halogen changes from F to I, the calculated ν4 Ru–X stretching vibrational frequencies of A1 symmetry in fac-Ru(CO)3 X3 − are 27–150 cm−1 higher than that in the cis-Ru(CO)2 X4 2− , while the calculated ν13 Ru–X stretching vibrational frequencies of E symmetry in fac-Ru(CO)3 X3 − are 24–45 cm−1 higher than those in cis-Ru(CO)2 X4 2−

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Table 5 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of cis-Ru(CO)2 X4 2− Method

Assignment

Ru(CO)2 F4 2−

Ru(CO)2 Cl4 2−

Ru(CO)2 Br4 2−

Ru(CO)2 I4 2−

RHF/LanL2DZ

A1 ν1 [νCO ] A1 ν2 [δRuCO ] A1 ν3 [νRuC ] A1 ν4 [νRuX ] A1 ν5 [νRuX ] A1 ν6 [δXRuX ] A1 ν7 [δCRuC ] A1 ν8 [δXRuX ] A2 ν9 [δRuCO ] A2 ν10 [δXRuX ] A2 ν11 [δCRuX ] B1 ν12 [δRuCO ] B1 ν13 [νRuX ] B1 ν14 [δCRuX ] B1 ν15 [δCRuX ] B2 ν16 [νCO ] B2 ν17 [δRuCO ] B2 ν18 [νRuC ] B2 ν19 [νRuX ] B2 ν20 [δXRuX ] B2 ν21 [δCRuX ]

2192 (519, 208) 605 (33, 2) 469 (123, 1) 394 (110, 1) 342 (15, 2) 187 (15, 3) 152 (3, 0.1) 87 (0.6, 2) 529 (0.2) 179 (0.2) 79 (1) 547 (32, 0.3) 403 (198, 0.1) 189 (5, 0.3) 90 (0.3, 0.8) 2135 (1432, 99) 506 (31, 0.05) 412 (56, 1) 347 (59, 1) 181 (12, 1) 101 (2, 0.5)

2247 (548, 286) 559 (59, 9) 333 (1, 8) 257 (47, 1) 216 (5, 1) 116 (5, 0.3) 102 (3, 2) 81 (3, 0.3) 499 (2) 103 (2) 85 (0.4) 509 (64, 1) 241 (102, 0.03) 120 (0.01, 0.6) 90 (0.1, 3) 2224 (740, 65) 462 (17, 0.004) 339 (0.001, 0.1) 231 (56, 0.1) 124 (8, 0.1) 86 (0.3, 0.1)

2252 (593, 403) 548 (65, 15) 329 (0.1, 13) 181 (23, 1) 129 (2, 1) 106 (1, 1) 75 (1, 1) 50 (1, 0.4) 490 (4) 87 (1) 63 (2) 499 (39, 1) 177 (60, 0.2) 103 (1, 0.1) 64 (0.5, 3) 2235 (626, 49) 452 (15, 0.1) 338 (0.3, 0.1) 156 (31, 0.2) 98 (0.1, 0.1) 65 (0.4, 0.1)

2249 (675, 634) 545 (74, 27) 334 (0.6, 24) 149 (49, 0.5) 107 (2, 2) 91 (1, 1) 58 (0.01, 1) 38 (0.4, 1) 486 (8) 93 (0.3) 47 (3) 497 (36, 1) 149 (14, 1) 106 (3, 0.6) 49 (2, 4) 2236 (549, 32) 448 (14, 1) 341 (1, 1) 125 (21, 0.4) 90 (1, 0.1) 54 (0.001, 0.1)

RHF/SDD

A1 ν1 [νCO ] A1 ν2 [δRuCO ] A1 ν3 [νRuC ] A1 ν4 [νRuX ] A1 ν5 [νRuX ] A1 ν6 [δXRuX ] A1 ν7 [δCRuC ] A1 ν8 [δXRuX ] A2 ν9 [δRuCO ] A2 ν10 [δXRuX ] A2 ν11 [δCRuX ] B1 ν12 [δRuCO ] B1 ν13 [νRuX ] B1 ν14 [δCRuX ] B1 ν15 [δCRuX ] B2 ν16 [νCO ] B2 ν17 [δRuCO ] B2 ν18 [νRuC ] B2 ν19 [νRuX ] B2 ν20 [δXRuX ] B2 ν21 [δCRuX ]

2173 (644, 183) 648 (31, 1) 490 (116, 1) 515 (16, 1) 387 (86, 1) 201 (11, 3) 165 (2, 0.3) 93 (0.2, 3) 549 (0.005) 189 (0.3) 89 (1) 575 (29, 0.1) 429 (215, 0.2) 201 (6, 0.3) 103 (1, 1) 2098 (1720, 123) 521 (34, 0.4) 430 (48, 0.4) 384 (86, 1) 191 (7, 2) 112 (1, 0.5)

2231 (647, 251) 597 (66, 6) 378 (0.1, 6) 264 (47, 1) 217 (4, 1) 121 (2, 0.4) 105 (1, 2) 86 (3, 0.1) 517 (1) 109 (0.2, 2) 89 (1) 534 (47, 0.1) 247 (100, 0.01) 126 (0.1, 0.2) 97 (0.004, 3) 2198 (919, 74) 479 (21, 0.1) 369 (6, 0.1) 232 (52, 0.04) 129 (4, 1) 90 (0.2, 0.1)

2242 (693, 240) 584 (67, 10) 370 (1, 9) 186 (27, 3) 126 (2, 2) 109 (1, 1) 79 (0.3, 1) 79 (0.3, 1) 507 (2) 92 (1) 67 (1) 523 (34, 0.2) 177 (74, 0.1) 109 (3, 0.4) 68 (1, 3) 2217 (729, 57) 468 (15, 1) 365 (1, 0.1) 155 (35, 1) 103 (0.1, 0.2) 68 (0.1, 0.1)

2240 (742, 306) 579 (77, 16) 375 (2, 15) 153 (14, 3) 109 (2, 2) 90 (2, 3) 62 (0.02, 0.5) 42 (0.3, 1) 502 (4) 97 (0.6) 51 (2) 519 (68, 0.1) 153 (50, 0.4) 109 (7, 0.6) 53 (2, 3) 2221 (599, 30) 464 (15, 2) 370 (0.1, 0.4) 126 (19, 2) 92 (3, 0.03) 56 (0.02, 0.2)

B3LYP/LanL2DZ

A1 ν1 [νCO ] A1 ν2 [δRuCO ] A1 ν3 [νRuC ] A1 ν4 [νRuX ] A1 ν5 [νRuX ] A1 ν6 [δXRuX ] A1 ν7 [δCRuC ] A1 ν8 [δXRuX ] A2 ν9 [δRuCO ] A2 ν10 [δXRuX ] A2 ν11 [δCRuX ] B1 ν12 [δRuCO ] B1 ν13 [νRuX ] B1 ν14 [δCRuX ] B1 ν15 [δCRuX ] B2 ν16 [νCO ] B2 ν17 [δRuCO ] B2 ν18 [νRuC ] B2 ν19 [νRuX ] B2 ν20 [δXRuX ] B2 ν21 [δCRuX ]

1904 (535, 53) 658 (6, 1) 532 (43, 14) 477 (73, 21) 428 (6, 10) 208 (2, 2) 175 (0.7, 0.6) 93 (0.1, 6) 567 (1) 194 (2) 88 (2) 606 (6, 0.03) 451 (163, 0.2) 205 (1, 2) 101 (3, 2) 1811 (1409, 32) 535 (17, 5) 514 (16, 6) 434 (61, 4) 199 (1, 1) 96 (2, 0.4)

1949 (654, 158) 622 (49, 2) 526 (8, 21) 270 (22, 17) 239 (6, 19) 123 (0.2, 0.2) 99 (0.4, 7) 89 (0.1, 1) 533 (0.03) 110 (7) 80 (2) 560 (30, 0.04) 281 (80, 0.1) 120 (0.02, 2) 93 (0.04, 6) 1877 (1020, 37) 512 (5, 11) 478 (19, 2) 236 (32, 3) 123 (0.04, 0.7) 73 (0.1, 0.2)

1949 (702, 207) 606 (66, 5) 523 (9, 24) 186 (7, 9) 144 (1, 17) 106 (0.4, 4) 74 (0.1, 2) 53 (0.001, 1) 517 (0.004) 80 (6) 64 (2) 545 (33, 0.2) 205 (43, 0.05) 96 (0.4, 1) 69 (1, 7) 1884 (870, 36) 507 (2, 11) 464 (29, 2) 156 (13, 3) 91 (1, 0.4) 57 (0.1, 0.2)

1945 (748, 260) 593 (81, 10) 521 (11, 27) 152 (3, 7) 105 (0.002, 15) 102 (1, 10) 58 (0.7, 2) 38 (0.001, 2) 505 (0.1) 83 (4) 49 (5) 537 (37, 0.6) 173 (30, 0.003) 96 (1, 2) 53 (1, 7) 1886 (728, 32) 502 (1, 9) 454 (21, 5) 124 (6, 5) 81 (3, 0.1) 49 (0.2, 0.3)

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Table 5 (Continued ) Method

Assignment

Ru(CO)2 F4 2−

Ru(CO)2 Cl4 2−

Ru(CO)2 Br4 2−

Ru(CO)2 I4 2−

B3LYP/SDD

A1 ν1 [νCO ] A1 ν2 [δRuCO ] A1 ν3 [νRuC ] A1 ν4 [νRuX ] A1 ν5 [νRuX ] A1 ν6 [δXRuX ] A1 ν7 [δCRuC ] A1 ν8 [δXRuX ] A2 ν9 [δRuCO ] A2 ν10 [δXRuX ] A2 ν11 [δCRuX ] B1 ν12 [δRuCO ] B1 ν13 [νRuX ] B1 ν14 [δCRuX ] B1 ν15 [δCRuX ] B2 ν16 [νCO ] B2 ν17 [δRuCO ] B2 ν18 [νRuC ] B2 ν19 [νRuX ] B2 ν20 [δXRuX ] B2 ν21 [δCRuX ]

1913 (574, 33) 670 (5, 0.5) 551 (4, 15) 486 (77, 19) 442 (11, 7) 218 (2, 1) 181 (0.3, 0.7) 95 (0.2, 6) 568 (1) 199 (2) 88 (2) 613 (5, 0.3) 472 (186, 0.003) 211 (1, 2) 106 (4, 2) 1818 (1385, 29) 546 (13, 6) 516 (15, 4) 445 (67, 2) 210 (1, 1) 102 (1, 0.4)

1953 (661, 86) 637 (44, 1) 541 (8, 23) 278 (20, 14) 244 (6, 15) 131 (0.04, 0.4) 102 (0.02, 6) 95 (0.1, 0.2) 538 (0.4) 117 (4) 81 (2) 571 (30, 0.7) 287 (80, 0.03) 128 (0.7, 1) 98 (0.1, 5) 1878 (1024, 33) 529 (7, 10) 485 (18, 2) 240 (31, 2) 131 (0.01, 1) 80 (0.01, 0.3)

1955 (722, 51) 621 (53, 3) 535 (9, 23) 190 (11, 11) 145 (2, 25) 107 (0.4, 3) 82 (0.2, 2) 61 (0.04, 0.3) 523 (0.1) 84 (6) 69 (1) 555 (27, 0.7) 205 (60, 0.6) 100 (0.6, 0.8) 77 (1, 6) 1888 (843, 40) 521 (2, 6) 471 (15, 4) 155 (19, 6) 98 (2, 0.2) 59 (0.01, 2)

1952 (739, 34) 606 (70, 6) 533 (10, 25) 155 (4, 8) 107 (0.1, 21) 103 (1, 11) 64 (0.7, 1) 43 (0.0001, 2) 510 (0.4) 85 (4) 53 (0.4) 547 (37, 2) 175 (36, 2) 99 (1, 1) 60 (1, 5) 1890 (760, 52) 517 (1, 4) 460 (16, 5) 126 (7, 8) 85 (3, 0.001) 51 (0.2, 0.5)

Experimental

A1 ν1 [νCO ] A1 ν2 [δRuCO ] A1 ν3 [νRuC ] A1 ν4 [νRuX ] A1 ν5 [νRuX ] B1 ν12 [δRuCO ] B1 ν13 [νRuX ] B2 ν16 [νCO ] B2 ν17 [δRuCO ] B2 ν18 [νRuC ] B2 ν19 [νRuX ]

2036 642 541 268

2032 631 535 183

2026 613

572 301 1935 500 478 259

562 211 1935 497 490 175

155 122 552 1940 456 131

Table 6 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of Ru(CO)3 X3 − Methods

Assignments

Ru(CO)3 F3 −

Ru(CO)3 Cl3 −

Ru(CO)3 Br3 −

Ru(CO)3 I3 −

RHF/LanL2DZ

ν1 A1 [νCO ] ν2 A1 [δRuCO ] ν3 A1 [νRuC ] ν4 A1 [νRuX ] ν5 A1 [δCRuC ] ν6 A1 [δXRuX ] ν7 A2 [δRuCO ] ν8 A2 [δXRuC ] ν9 E[νCO ] ν10 E[δRuCO ] ν11 E[δRuCO ] ν12 E[νRuC ] ν13 E[νRuX ] ν14 E[δXRuC ] ν15 E[δXRuC ] ν16 E[δXRuC ]

2296 (228, 195) 510 (162, 0.6) 307 (1, 2) 576 (14, 3) 189 (16, 1) 94 (1, 1) 471 111 2256 (846, 111) 540 (14, 2) 495 (82, 0.6) 469 (27, 0.8) 326 (14, 3) 187 (5, 0.6) 119 (9, 0.7) 83 (0.8, 2)

2303 (471, 292) 558 (102, 8) 343 (5, 7) 292 (35, 1) 122 (2, 0.3) 104 (0.2, 3) 457 95 2277 (612, 74) 535 (33, 6) 460 (13, 0.4) 351 (3, 0.5) 276 (46, 1) 129 (3, 0.3) 104 (0.2, 3) 91 (1, 0.04)

2296 (645, 382) 555 (117, 12) 337 (2, 6) 213 (18, 4) 111 (2, 1) 76 (0.7, 3) 450 83 2274 (558, 69) 532 (38, 10) 453 (12, 0.4) 350 (1, 0.01) 191 (26, 2) 113 (2, 0.3) 95 (0.5, 2) 65 (0.001, 1)

2284 (896, 514) 557 (131, 20) 345 (8, 7) 177 (10, 4) 110 (1, 2) 60 (0.01, 3) 448 81 2264 (513, 65) 532 (46, 17) 451 (13, 0.9) 352 (2, 0.5) 157 (16, 3) 110 (2, 0.9) 93 (0.03, 0.7) 51 (0.005, 2)

RHF/SDD

ν1 A1 [νCO ] ν2 A1 [δRuCO ] ν3 A1 [νRuC ] ν4 A1 [νRuX ] ν5 A1 [δCRuC ] ν6 A1 [δXRuX ] ν7 A2 [δRuCO ] ν8 A2 [δXRuC ]

2287 (285, 196) 510 (92, 0.2) 347 (2, 1) 611 (25, 2) 200 (13, 2) 99 (0.6, 1) 482 118

2294 (538, 266) 592 (118, 6) 374 (0.1, 0.6) 305 (40, 3) 129 (1, 0.2) 107 (2, 3) 469 100

2289 (735, 261) 587 (126, 8) 373 (3, 3) 221 (21, 6) 114 (2, 1) 82 (0.4, 2) 463 86

2278 (976, 278) 587 (144, 11) 380 (0.1, 0.02) 182 (11, 7) 113 (3, 1) 66 (0.006, 2) 459 84

Y. Zhang et al. / Spectrochimica Acta Part A 61 (2005) 697–706

703

Table 6 (Continued ) Assignments

Ru(CO)3 F3 −

Ru(CO)3 Cl3 −

Ru(CO)3 Br3 −

Ru(CO)3 I3 −

ν9 E[νCO ] ν10 E[δRuCO ] ν11 E[δRuCO ] ν12 E[νRuC ] ν13 E[νRuX ] ν14 E[δXRuC ] ν15 E[δXRuC ] ν16 E[δXRuC ]

2233 (998, 129) 572 (19, 1) 528 (167, 0.6) 485 (19, 1) 352 (25, 3) 196 (4, 0.8) 128 (7, 1) 87 (0.5, 2)

2259 (731, 84) 563 (41, 4) 475 (18, 0.4) 375 (0.7, 4) 281 (48, 1) 135 (2, 0.5) 110 (0.03, 3) 94 (0.7, 0.3)

2258 (646, 80) 560 (43, 8) 468 (14, 0.8) 374 (0.07, 0.2) 192 (29, 3) 117 (2, 0.3) 98 (0.3, 2) 70 (0.003, 1)

2251 (170, 65) 558 (54, 14) 466 (14, 2) 382 (9, 2) 157 (15, 5) 113 (2, 2) 96 (0.09, 0.7) 55 (0.006, 2)

B3LYP/LanL2DZ

ν1 A1 [νCO ] ν2 A1 [δRuCO ] ν3 A1 [νRuC ] ν4 A1 [νRuX ] ν5 A1 [δCRuC ] ν6 A1 [δXRuX ] ν7 A2 [δRuCO ] ν8 A2 [δXRuC ] ν9 E[νCO ] ν10 E[δRuCO ] ν11 E[δRuCO ] ν12 E[νRuC ] ν14 E[δXRuC ] ν15 E[δXRuC ] ν16 E[δXRuC ]

2035 (266, 99) 527 (95, 7) 461 (1, 20) 623 (15, 2) 203 (2, 2) 111 (3, 1) 482 97 1942 (1105, 93) 592 (16, 0.2) 508 (49, 0.08) 488 (12, 2) 195 (0.4, 1) 109 (4, 1) 84 (0.04, 6)

2038 (476, 196) 603 (94, 1) 480 (6, 13) 309 (14, 19) 121 (0.2, 0.1) 98 (1, 7) 451 75 1965 (806, 87) 562 (35, 2) 466 (14, 2) 465 (9, 2) 117 (0.1, 0.4) 96 (0.03, 7) 82 (0.1, 0.6)

2028 (609, 229) 592 (118, 2) 481 (4, 14) 217 (4, 13) 106 (0.3, 3) 71 (0.08, 5) 437 65 1961 (711, 88) 548 (43, 3) 462 (0.4, 3) 453 (19, 1) 105 (0.4, 2) 82 (0.1, 4) 60 (0.005, 2)

2016 (775, 268) 583 (138, 7) 481 (1, 16) 177 (1, 10) 103 (0.4, 4) 58 (0.03, 6) 427 63 1953 (614, 89) 538 (53, 4) 462 (0.2, 2) 442 (21, 3) 103 (1, 3) 80 (1, 2) 48 (0.002, 3)

B3LYP/SDD

ν1 A1 [νCO ] ν2 A1 [δRuCO ] ν3 A1 [νRuC ] ν4 A1 [νRuX ] ν5 A1 [δCRuC ] ν6 A1 [δXRuX ] ν7 A2 [δRuCO ] ν8 A2 [δXRuC ] ν9 E[νCO ] ν10 E[δRuCO ] ν11 E[δRuCO ] ν12 E[νRuC ] ν13 E[νRuX ] ν14 E[δXRuC ] ν15 E[δXRuC ] ν16 E[δXRuC ]

2037 (288, 95) 541 (110, 0.4) 477 (0.3, 24) 636 (13, 1) 216 (2, 2) 97 (0.01, 4) 481 101 1941 (1136, 85) 603 (17, 0.06) 514 (69, 0.1) 497 (4, 1) 469 (28, 6) 203 (0.5, 1) 120 (4, 1) 85 (0.01, 6)

2041 (483, 153) 615 (93, 0.6) 495 (7, 14) 317 (14, 19) 129 (0.2, 0.4) 101 (0.5, 6) 456 79 1964 (845, 82) 575 (38, 0.7) 477 (8, 3) 472 (16, 2) 285 (26, 6) 124 (0.05, 0.8) 102 (0.002, 6) 85 (0.05, 1)

2032 (638, 129) 605 (110, 1) 495 (4, 16) 222 (6, 16) 108 (0.1, 3) 80 (0.1, 5) 445 68 1960 (731, 93) 564 (42, 2) 474 (2, 2) 459 (16, 3) 190 (15, 8) 107 (0.4, 10) 87 (0.05, 5) 66 (0.002, 2)

2021 (786, 113) 596 (137, 2) 499 (2, 19) 182 (2, 12) 105 (0.5, 5) 64 (0.01, 4) 433 66 1955 (628, 89) 552 (55, 3) 474 (0.4, 1) 449 (18, 3) 154 (6, 9) 104 (1, 3) 84 (0.5, 2) 52 (0.0003, 3)

Experimental

ν1 A1 [νCO ] ν2 A1 [δRuCO ] ν3 A1 [νRuC ] ν4 A1 [νRuX ] ν9 E[νCO ] ν10 E[δRuCO ] ν12 E[νRuC ] ν13 E[νRuX ]

2137 575 512 315 2061 616 480 282

2126 567 495 288 2066 604 468 208

2110 552 480 196 2035 590 460 174

Methods

B2 symmetry ν19 . Similar trends can be found in other methods. The complexes of Ru(CO)5 X+ belong to C4v symmetry. There are 30 fundamental vibrations are reduced to vib = 7A1 + A2 + 2B1 + 4B2 + 8E, in which, A1 and E are both IR and Raman active, B1 is Raman active only, and A2 is inactive. In the complex, 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 Ru–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 RuC stretching and CRuC bending are not only dependent on the theoretical methods but also on the substituted halogen atoms.

704

Y. Zhang et al. / Spectrochimica Acta Part A 61 (2005) 697–706

Table 7 Calculated vibrational frequencies (cm−1 ) and intensities (km/mol) of Ru(CO)5 X+ Method

Assignment

Ru(CO)5 F+

Ru(CO)5 Cl+

Ru(CO)5 Br+

Ru(CO)5 I+

RHF/LanL2DZ

ν1 A1 [νCO ] ν2 A1 [νCO ] ν3 A1 [δRuCO ] ν4 A1 [νRuC ] ν5 A1 [νRuC ] ν6 A1 [νRuX ] ν7 A1 [δCRuC ] ν8 A2 [νRuC ] ν9 B1 [δRuCO ] ν10 B1 [δCRuC ] ν11 B2 [νCO ] ν12 B2 [δRuCO ] ν13 B2 [δRuCO ] ν14 B2 [δCRuC ] ν15 E[νCO ] ν16 E[δRuCO ] ν17 E[δRuCO ] ν18 E[δRuCO ] ν19 E[νRuC ] ν20 E[δCRuX ] ν21 E[δCRuX ] ν22 E[δCRuC ]

2424 (0.01, 175) 2382 (258, 88) 518 (122, 0.4) 306 (1, 1) 278 (0.4, 0.1) 607 (18, 3) 107 (0.1, 0.3) 320 463 (5) 97 (4) 2405 (113) 483 (0.1) 299 (1) 74 (0.8) 2401 (526, 4) 519 (49, 0.1) 365 (2, 3) 390 (1, 0.3) 299 (0.2, 0.2) 154 (17, 0.4) 104 (0.05, 0.5) 84 (0.003, 2)

2420 (19, 201) 2384 (353, 115) 548 (80, 3) 308 (1, 0.5) 287 (5, 0.01) 376 (19, 4) 116 (0.04, 0.3) 326 471 (4) 98 (4) 2401 (121) 490 (0.6) 310 (0.7) 81 (0.004) 2397 (568, 0.01) 527 (53, 0.2) 471 (5, 4) 386 (0.3, 0.03) 310 (2, 0.5) 122 (7, 0.5) 101 (1, 3) 81 (0.1, 1)

2413 (54, 221) 2381 (347, 135) 549 (102, 5) 328 (4, 4) 295 (0.4, 1) 238 (14, 5) 115 (0.2, 0.1) 329 373 (4) 99 (4) 2395 (131) 490 (1) 312 (0.6) 85 (0.001) 2391 (605, 2) 430 (54, 0.2) 471 (6, 5) 384 (1, 0.02) 313 (0.06, 0.6) 115 (2, 0.1) 92 (0.7, 4) 82 (1, 0.05)

2405 (133, 247) 2377 (326, 162) 554 (126, 11) 322 (4, 4) 295 (2, 2) 197 (9, 9) 115 (1, 1) 332 478 (3) 100 (4) 2386 (149) 492 (3) 317 (0.7) 88 (0.03) 2382 (664, 12) 534 (55, 0.2) 471 (8, 7) 383 (3, 0.001) 317 (0.5, 2) 114 (2, 0.02) 93 (0.3, 3) 76 (1, 0.3)

RHF/SDD

ν1 A1 [νCO ] ν2 A1 [νCO ] ν3 A1 [δRuCO ] ν4 A1 [νRuC ] ν5 A1 [νRuC ] ν6 A1 [νRuX ] ν7 A1 [δCRuC ] ν8 A2 [νRuC ] ν9 B1 [δRuCO ] ν10 B1 [δCRuC ] ν11 B2 [νCO ] ν12 B2 [δRuCO ] ν13 B2 [δRuCO ] ν14 B2 [δCRuC ] ν15 E[νCO ] ν16 E[δRuCO ] ν17 E[δRuCO ] ν18 E[δRuCO ] ν19 E[νRuC ] ν20 E[δCRuX ] ν21 E[δCRuX ] ν22 E[δCRuC ]

2421 (46, 0.005) 2368 (430, 105) 533 (147, 0.3) 328 (4, 2) 303 (0.3, 0.1) 616 (14, 3) 111 (0.3, 0.3) 324 479 (4) 99 (4) 2399 (134) 490 (0.1) 318 (1) 75 (0.1) 2392 (594, 6) 537 (68, 0.1) 490 (0.4, 2) 396 (0.5, 0.3) 360 (0.4, 0.3) 160 (15, 0.3) 107 (0.005, 0.6) 87 (0. 03, 2)

2416 (21, 208) 2371 (426, 134) 559 (103, 3) 323 (13, 1) 312 (4, 0.003) 380 (19, 10) 118 (0.03, 0.1) 328 482 (4) 100 (4) 2395 (134) 494 (0.4) 325 (1) 83 (0.02) 2389 (628, 0.06) 542 (73, 0.3) 494 (2, 3) 394 (0.3, 1) 314 (0.8, 0.03) 129 (7, 0.5) 104 (0.5, 3) 89 (0.1, 1)

2410 (55, 210) 2368 (422, 157) 562 (125, 5) 350 (0.8, 5) 315 (2, 0.1) 242 (17, 7) 117 (0.1, 0.2) 330 485 (4) 100 (4) 2389 (141) 495 (0.6) 328 (0.7) 86 (0.01) 2382 (662, 1) 543 (72, 0.4) 494 (4, 4) 393 (1, 0.1) 3161 (1, 0.3,) 118 (3, 0.003) 96 (0.7, 4) 84 (1, 0.01)

2402 (134, 220) 2366 (401, 182) 566 (157, 9) 348 (0.3, 6) 320 (5, 0.2) 198 (9, 10) 117 (0.7, 1) 335 491 (4) 101 (4) 2380 (152) 494 (1) 333 (0.04) 90 (0.004) 2373 (718, 9) 548 (72, 0.4) 494 (7, 6) 392 (2, 0.1) 322 (3, 1) 117 (2, 0.04) 96 (0.3, 4) 79 (1, 0.2)

B3LYP/LanL2DZ

ν1 A1 [νCO ] ν2 A1 [νCO ] ν3 A1 [δRuCO ] ν4 A1 [νRuC ] ν5 A1 [νRuC ] ν6 A1 [νRuX ] ν7 A1 [δCRuC ] ν8 A2 [νRuC ] ν9 B1 [δRuCO ] ν10 B1 [δCRuC ] ν11 B2 [νCO ] ν12 B2 [δRuCO ] ν13 B2 [δRuCO ] ν14 B2 [δCRuC ] ν15 E[νCO ] ν16 E[δRuCO ] ν17 E[δRuCO ] ν18 E[δRuCO ]

2177 (0.03, 224) 2079 (469, 142) 581 (34, 0.3) 401 (9, 1) 395 (2, 9) 533 (72, 8) 104 (0.01, 0.5) 336 477 (1) 98 (8) 2134 (272) 506 (0.02) 381 (0.01) 68 (0.1) 2113 (656, 14) 565 (72, 0.01) 505 (0.06, 0.4) 397 (0.04, 0.3)

2168 (14, 226) 2080 (446, 178) 575 (104, 0.04) 415 (0.085, 2) 402 (0.002, 10) 330 (13, 13) 113 (0.2, 0.1) 339 480 (0.7) 99 (8) 2126 (255) 493 (0.2) 388 (0.2) 73 (0.02) 2106 (879, 3) 564 (73, 0.002) 498 (3, 1) 386 (1, 1)

2160 (37, 228) 2079 (438, 207) 574 (124, 0.2) 409 (0.5, 4) 402 (0.3, 8) 228 (5, 10) 112 (0.6, 0.1) 340 482 (0.6) 99 (8) 2119 (255) 484 (0.7) 390 (0.1) 75 (0.002) 2099 (710, 1) 563 (72, 0.02) 792 (5, 2) 382 (3, 1)

2151 (85, 234) 2075 (429, 250) 576 (147, 0.9) 408 (0.01, 13) 398 (2, 1) 185 (2, 8) 110 (1, 0.8) 342 484 (0.4) 99 (0.05, 5) 2109 (256) 476 (2) 396 (1) 78 (0.01) 2090 (756, 2) 563 (69, 0.1) 486 (8, 3) 380 (7, 2)

Y. Zhang et al. / Spectrochimica Acta Part A 61 (2005) 697–706

705

Table 7 (Continued ) Method

B3LYP/SDD

Assignment

Ru(CO)5 F+

Ru(CO)5 Cl+

Ru(CO)5 Br+

Ru(CO)5 I+

ν19 E[νRuC ] ν20 E[δCRuX ] ν21 E[δCRuX ] ν22 E[δCRuC ]

335 (18, 1) 145 (4, 0.1) 102 (0.1, 2) 86 (0.07, 4)

348 (16, 0.3) 115 (1, 0.02) 92 (1, 6) 86 (0.5, 0.6)

352 (15, 0.1) 111 (0.5, 0.4) 89 (0.04, 5) 71 (1, 0.6)

355 (13, 0.002) 109 (0.4, 0.6) 90 (0.05, 5) 64 (1, 0.5)

ν1 A1 [νCO ] ν2 A1 [νCO ] ν3 A1 [δRuCO ] ν4 A1 [νRuC ] ν5 A1 [νRuC ] ν6 A1 [νRuX ] ν7 A1 [δCRuC ] ν8 A2 [νRuC ] ν9 B1 [δRuCO ] ν10 B1 [δCRuC ] ν11 B2 [νCO ] ν12 B2 [δRuCO ] ν13 B2 [δRuCO ] ν14 B2 [δCRuC ] ν15 E[νCO ] ν16 E[δRuCO ] ν17 E[δRuCO ] ν18 E[δRuCO ] ν19 E[νRuC ] ν20 E[δCRuX ] ν21 E[δCRuX ] ν22 E[δCRuC ]

2176 (0.03, 221) 2071 (522, 140) 590 (25, 0.6) 420 (5, 6) 404 (7, 6) 547 (78, 10) 105 (0.002, 0.5) 334 482 (0.6) 99 (8) 2132 (280) 503 (0.05) 390 (0.01) 67 (0.2) 2108 (714, 15) 571 (84, 0.002) 514 (0.3, 0.4) 397 (0.02, 0.3) 344 (23, 1) 155 (4, 0.2) 103 (0.001, 2) 87 (0.1, 4)

2168 (15, 216) 2075 (491, 173) 579 (12, 0.04) 429 (0.3, 0.2) 413 (0.1, 14) 331 (12, 12) 113 (0.1, 0.1) 337 486 (0.6) 99 (8) 2124 (254) 489 (0.1) 398 (0.2) 73 (0.05) 2102 (727, 3) 569 (87, 0.002) 507 (1, 1) 387 (2, 1) 357 (20, 0.4) 118 (2, 0.001) 96 (0.4, 5) 86 (0.3, 1)

2161 (37, 206) 2072 (490, 203) 579 (14, 0.05) 423 (1, 0.7) 414 (0.04, 14) 230 (6, 10) 111 (0.4, 0.2) 338 486 (0.7) 99 (8) 2117 (248) 481 (0.3) 400 (0.5) 75 (0.03) 2096 (751, 0.3) 568 (84, 0.001) 503 (3, 2) 384 (4, 1) 360 (19, 0.1) 112 (1, 0.5) 90 (0.07, 5) 73 (1, 0.4)

2152 (84, 201) 2070 (478, 239) 579 (17, 0.1) 419 (1, 4) 417 (0.1, 14) 187 (2, 9) 111 (1, 1) 341 489 (0.7) 100 (8) 2107 (242) 471 (1) 404 (1) 78 (0.01) 2087 (787, 1) 568 (81, 0.02) 498 (6, 3) 382 (9, 3) 363 (14, 0.05) 111 (1, 1) 91 (0.1, 5) 66 (1, 0.4)

3.3. Vibrational intensities As shown in parentheses of Tables 4–7, the calculated intensities are mainly dependent on the theoretical methods, rather than basis sets. In the complexes Ru(CO)6 2+ and cis-Ru(CO)2 X4 2− , the vibrational intensities calculated at B3LYP level correctly give relative tendency of the major intensities in the experimental vibrational spectra, while the RHF method are significantly lower than that calculated by B3LYP method. The intensity of antisymmetric vibrations may be used as a measurement of the extent of bonding in this type of complexes [30]. 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 Ru atom because of their smaller electronegativity, therefore, a tendency for back of ␲-bonding electrons to the carbonal ligand would be expected.

lated data are slightly improved by SDD basis set. The deviations between calculated and experimental values are quite smooth for a given type of vibration. The C–O stretching vibrational frequencies and Ru–X, Ru–C stretching frequencies and the RuCN 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 National Natural Science Foundation of China (No. 29871017) and the National Natural Science Foundation of Jiangsu Educational Office (No. 00KJB 15009).

References 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 Ru(II) complexes, with both basis sets concerned. For a given method, the calcu-

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