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3D supramolecular network constructed by intermolecular interactions in mixed ligand complex of zinc
Inorganic Chemistry Communications 8 (2005) 1090–1093 www.elsevier.com/locate/inoche
3D supramolecular network constructed by intermolecular interactions in mixed ligand complex of zinc Danuta Dobrzyn´ska a
a,*
, Tadeusz Lis b, Lucjan B. Jerzykiewicz
b
Faculty of Chemistry, Wrocław University of Technology, Wybrze_ze Wyspian´skiego 27, 50-370 Wrocław, Poland b Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland Received 22 June 2005; accepted 7 September 2005 Available online 19 October 2005
Abstract New complex [Zn(quin-2-c)2(Him)2] (quin-2-c = quinoline-2-carboxylate ion, Him = imidazole) was synthesized by self assembly and its structure was determined by X-ray analysis. The compound crystallizes in P21/c space group. Four independent molecules of complex are present in the structure. Strong hydrogen bonds create three different 1D chains which are collected in two different layers. The alternately packed layers form the 3D supramolecular structure. The interchain and interlayer contacts are of the C–H O, p p and C– H p type. The influence of strong hydrogen bond on the vibrational characteristics of the monodentately coordinated carboxylate group in zinc complexes with quin-2-c ion is discussed. 2005 Elsevier B.V. All rights reserved. Keywords: Zinc complex; Crystal structure; Supramolecular network; Hydrogen bonds; Infrared spectra
Carboxylates are efficient catalysts in the biological and chemical processes [1]. The carboxylate group offers a variety of coordination modes and many types of complexes are known [2]. The need for characterization of the metal enzyme centers as well as the searches for new catalytic or magnetic materials causes an incessant interest in carboxylate chemistry. Quinoline-2-carboxylic acid is the biological compound involved in the metabolism of tryptophan [3]. It is a strong chelator providing the donor set similar to that responsible for binding metal ion in PQQ cofactor of quinoprotein family [4]. To date three zinc complexes with quin-2-c ion have been obtained and structurally characterized: [Zn(MEDA)(quin-2-c)] [5] (MEDA = N-(2-mercaptoethyl)picolylamine), [Zn(quin-2-c)2(1-Meim)2] [6] and [Zn(quin-2-c)2(H2O)] [7]. In these complexes, quin-2-c ion binds in a N,O chelate mode and the metal environment mimics the zinc enzyme centers. In the crystals of the mentioned compounds, strong hydrogen bonds and *
Corresponding author. Tel.: +48 71 320 3909; fax: +48 71 328 4330. E-mail address: [email protected] (D. Dobrzyn´ska).
1387-7003/$ - see front matter 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2005.09.009
weak intermolecular interactions of the C–H O, C– H p and p p type lead to the formations of 2D and 3D supramolecular frameworks. As a continuation of our interest in quinoline-2-carboxylates, we have synthesized [Zn(quin-2-c)2(Him)2] and studied its crystal structure. The significant differences in the hydrogen bonding systems in [Zn(quin-2-c)2(1-Meim)2], [Zn(quin-2-c)2(H2O)] and [Zn(quin-2-c)2(Him)2] are expressively reflected in the vibrational characteristics of the monodentate carboxylate group. cis-Bis(quinoline-2-carboxylato) bis imidazole zinc(II) was obtained from the reaction of Zn(ClO4)2 Æ 6H2O with a twofold excess quinoline-2-carboxylic acid and five equivalents of imidazole in the form of the single crystals. Crystals are air stable and have very limited solubility in common organic solvents [8]. The crystal structure of the complex was determined by single-crystal X-ray diffraction [9,10]. In the crystal of [Zn(quin-2-c)2(Him)2], four independent molecules of the complex have been found (a, b, c and d). A drawing of the molecular structure (Fig. 1) represents the molecule of the title complex.
D. Dobrzyn´ska et al. / Inorganic Chemistry Communications 8 (2005) 1090–1093
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Table 2 ˚ ), () Hydrogen bonds for Zn(quin-2-c)2 (Him) (A D–H A
d(D–H) d(H A) d(D A) \(DHA) (i)
N(22)–H(22) . . . O(12) N(22A)–H(22B) . . . O(2A)(ii) N(22B)–H(22C) . . . O(2C) N(22C)–H(22D) . . . O(2B)(iii) N(32)–H(32) . . . O(2)(iv) N(32A)–H(32B) . . . O(12A)(v) N(32B)–H(32C) . . . O(12C)(vi) N(32C)–H(32D) . . . O(12B) C(9A)–H(9AA) . . . O(11A) C(32A)–H(32B) . . . O(2C)(vii) C(9)–H(9A) . . . O(11) C(9B)–H(9BA) . . . O(11B) C(22B)–H(22C) . . . O(12A)(viii) C(19)–H(19A) . . . O(1) C(19A)–H(19B) . . . O(1A) C(19B)–H(19C) . . . O(1B) C(19C)–H(19D) . . . O(1C) C(9C)–H(9CA) . . . O(11C) C(22)–H(22A) . . . O(2B)(ix) C(22C)–H(22D) . . . O(12)(viii) Fig. 1. The molecular structure of the title complex (a) with the atom numbering scheme. The displacement ellipsoids are drawn at the 50% probability level.
The selected bond distances and angles for a, b, c and d are collected in Table 1. Table 2 lists the hydrogen bonds of N–H O and C–H O type. The geometry of the molecules a, b, c and d is the same but the molecular parameters display significant differences (see Table 1). The Zn2+ ion is six coordinated with the O2N4 donor set. The quin-2-c ion binds to zinc in a chelate mode, through the carboxylate O atom and the quinoline N atom. The carboxylate group is monodentate. The chelate rings are almost coplanar with the quinoline rings, the medium angle between quinoline
Table 1 ˚ ) and angles () for Zn(quin-2-c)2 (Him)2 Selected bond lengths (A Bond distances Zn(1)–O(11) Zn(1)–O(1) Zn(1)–N(21) Zn(1)–N(31) Zn(1)–N(1) Zn(1)–N(11)
a 2.047(3) 2.048(3) 2.109(4) 2.117(4) 2.329(4) 2.375(4)
b 2.030(3) 2.052(3) 2.115(4) 2.131(4) 2.293(4) 2.418(4)
2.014(3) 2.045(3) 2.104(4) 2.133(4) 2.353(4) 2.354(4)
2.020(3) 2.043(3) 2.088(4) 2.135(4) 2.399(4) 2.399(4)
Bond angles O(11)–Zn(1)–N(21) O(1)–Zn(1)–N(21) O(11)–Zn(1)–N(31) O(1)–Zn(1)–N(31) N(21)–Zn(1)–N(31) O(11)–Zn(1)–N(1) O(1)–Zn(1)–N(1) N(21)–Zn(1)–N(1) O(11)–Zn(1)–N(11) O(1)–Zn(1)–N(11) N(31)–Zn(1)–N(11) N(1)–Zn(1)–N(11)
95.85(15) 92.84(15) 91.63(15) 95.70(15) 90.56(16) 96.64(14) 76.64(14) 85.45(15) 75.43(14) 96.36(14) 85.61(15) 99.52(14)
95.15(12) 95.42(13) 90.92(13) 96.47(12) 89.66(14) 96.39(12) 76.38(12) 89.47(14) 74.99(11) 95.65(12) 81.43(13) 100.64(13)
96.10(14) 92.21(14) 93.68(14) 95.01(14) 89.92(15) 96.62(14) 75.62(14) 83.78(15) 76.42(13) 95.55(13) 88.15(14) 99.36(13)
96.22(15) 91.13(14) 94.64(14) 95.79(14) 91.01(15) 95.06(14) 75.10(13) 84.40(15) 76.86(14) 96.18(14) 86.95(14) 98.73(14)
c
d
0.88 0.88 0.88 0.88 0.88 0.88 0.88 0.88 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95
1.85 1.85 1.85 1.85 1.85 1.89 1.87 1.85 2.20 2.44 2.23 2.27 2.55 2.28 2.33 2.26 2.24 2.27 2.52 2.49
2.728(6) 2.728(5) 2.722(6) 2.723(6) 2.722(6) 2.767(5) 2.733(5) 2.726(6) 3.078(5) 3.164(7) 3.107(7) 3.141(6) 3.186(7) 3.160(7) 3.208(5) 3.133(6) 3.113(6) 3.147(6) 3.196(7) 3.186(7)
172 171 169 168 170 172 168 174 152 133 154 152 124 154 153 152 152 153 128 130
Symmetry transformations used to generate equivalent atoms: (i) x, y, z + 2; (ii) x, y 1/2, z 1/2; (iii) x, y, z + 1; (iv) 4 x, y, z + 1; (v) x, y 1/2, z 3/2; (vi) 6 x, y, z 1; (vii) x 1, y 1/2, z 3/2; (viii) x + 1, y, z; (ix) x + 1, y, z + 1.
rings in a, b, c and d equals 113.8(1). Two molecules of imidazole connected with zinc by aromatic nitrogen atoms are located in cis position. The medium value of Zn–NHim ˚ , is very close to that found for distance, 2.116(4) A [Zn(quin-2-c)2(1-Meim)2] [6] and is a little longer than the ˚) typical value observed for octahedral complexes (2.084 A [11]. Zinc–oxygen bond lengths in the studied complex are close to the literature data [5–7,11]. The zinc–quinoline ˚ nitrogen distances in a, b, c and d are very long (2.354(4) A – medium value) when compared with those observed for other complexes of Zn with quin-2-c ion as well as in the octahedral complexes of zinc with pyridine ligands ˚ ) [11]. The geometry around zinc ion is severely (2.111 A distorted. The bite angle of the chelating ligand is very small in the studied compound. Its medium value equals 75.93(4), whereas the relevant values are 79.5 and 78.33 for [Zn(quin-2-c)2(H2O)] [7] and 77.9 for [Zn(quin-2-c)2(1-Meim)2] [6]. The intramolecular hydrogen bond of the C–H O type stabilizes the molecules of a, b, c and d, see Table 2. Various intermolecular interactions organize the supramolecular structure of the crystal. The strong hydrogen
Fig. 2. Chain of molecules of [Zn(quin-2-c)2(Him)2] connected by strong hydrogen bonds extending along c-axis.
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D. Dobrzyn´ska et al. / Inorganic Chemistry Communications 8 (2005) 1090–1093
bonds of the N–H O type (Table 2) create the 1D chains propagating along the crystallographic c-axis, Fig. 2. Three different chains can be distinguished: the first made of molecules a, the second built of molecules b and third comprising alternately positioned molecules c and d. The chains are collected in layers, Fig. 3. Two former chains are alternately packed in layer A, while layer B is made of the latter type of chains. Layers A and B are lo-
Fig. 3. Packing in the crystal of [Zn(quin-2-c)2(Him)2] viewed along the caxis. Layers A contain two types of chains, one made of a and second made of b. Layers B contain one type of chain, made of c and d. Dotted lines indicate stacking interactions. Atoms participating in the interlayer C–H O bonds are marked as balls.
˚ , d^ = 3.557 A ˚ ) and C–H p Fig. 4. p p contacts (Cg Cg = 3.738 A ˚, interactions between molecules b and d (a: d(C–H Cg) = 3.443(6) A ˚ , \(C–H Cg) = 174.5 ; b: d(C–H Cg) = 3.608(6) A ˚, d(H Cg) = 2.495 A ˚ , \(C–H Cg) = 162.0). Hydrogen atoms particid(H Cg) = 2.693 A pating in C–H p interactions with other neighbors are indicated.
cated alternately and create the 3D structure. The interchain interactions within layers are of the offset p p type [12]. The interlayer p p interactions are accompanied by C–H O hydrogen bonds and C–H p contacts, Figs. 3 and 4. The Dm(COO) = mas(COO) ms(COO) value which is commonly used in diagnosing the nature of carboxylate coordination follows the order Dmmonodentate > Dmionic Dmbridging > Dmchelate [13]. However, it is known that strong hydrogen bonding to the oxygen atom, not coordinated to the metal ion, in complexes with monodentate carboxylate group decreases the Dm value; this fact is very often neglected. To show the magnitude of the changes in D(COO) value caused by strong hydrogen bonding, we have compared the vibrational and structural characteristics of carboxylate group in [Zn(quin-2-c)2(Him)2] and [Zn(quin-2-c)2(1-Meim)2] (Table 3). In both compounds, the COO group of quin-2-c ligand binds to zinc in monodentate mode and the donor sets around the Zn2+ ions are the same (N4O2). The secondary ligands, imidazole and 1-methylimidazole, also coordinate to zinc in the same manner, through the aromatic (N3) nitrogen atom. In the crystal of [Zn(quin-2-c)2(Him)2], the strong hydrogen bridges of N–H O type are observed, whereas in [Zn(quin-2-c)2(1-Meim)2] only weak C–H O interactions are found. The Dm found for the former compound (223 cm 1) is smaller by 53 cm 1 than that observed for the latter complex (276 cm 1). According to the general rule, this value is characteristic of carboxylate bridging mode. The Dm value corresponding to the monodentate carboxylate group in [Zn(quin-2-c)2 (H2O)] is also significantly smaller than expected, and equals 240 cm 1. In this complex, strong intermolecular hydrogen bond between the coordinated water molecule and the carboxylate oxygen atom has been found (Table 3). Such low values of Dm have been reported for other monodentate carboxylates with C@O group involved in strong hydrogen bond [14] in all these cases the results of the X-ray analysis allowed to assign unambiguously the binding mode of carboxylate group. In conclusion, the new mixed ligand complex of zinc has been obtained by self assembly. The carboxylate ligands and imidazole molecules complete the strongly distorted octahedral coordination sphere around Zn2+ ion in cis configuration. In the crystal, four independent molecules are found. The title complex forms the supramolecular structure due to a variety of intermolecular interactions. Strong
Table 3 Comparison of vibrational and structural data for [Zn(quin-2-c)2 (Him)2], [Zn(quin-2-c)2 (1-Meim)2] and [Zn(quin-2-c)2 (H2O)] ˚) ˚) Compound mas(COO) (cm 1) ms(COO) (cm 1) Dm(COO) (cm 1) rC-O(M) (A rC@O (A [Zn(quin-2-c)2(Him)2] [Zn(quin-2-c)2(1-Meim)2]b [Zn(quin-2-c)2(H2O)]c a b c
Medium value. Ref. [6]. Ref. [7].
1618 1642 1630
1395 1366 1390
223 276 240
a
1.242 1.227 1.226a
a
1.254 1.273 1.270a
Hydrogen bond N–H O C–H O O–H O
D. Dobrzyn´ska et al. / Inorganic Chemistry Communications 8 (2005) 1090–1093
intermolecular hydrogen bonds create three types of 1D chains. The chains are arranged in two different layers which are packed alternately into 3D structure. The two latter supramolecular motifs result from the C–H O, C– H p and p p type interactions. Strong hydrogen bonds severely influence the vibrational characteristics of the carboxylate group. It is shown that the determination of the type of coordination of the carboxylate group cannot be made on the basis of their IR spectra only. Appendix A. Supplementary data Crystallographic data for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Center as supplementary publication No. CCDC 271897. Copies of the data can be obtained free of charge from CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44 1223 336 033; e-mail: [email protected]). Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.inoche.2005.09.009. References [1] (a) S. Kiani, A. Tapper, J.R. Staples, P. Stavropoulos, J. Am. Chem. Soc. 122 (2000) 7503; (b) J.J.R. Frau´sto da Silva, R.J.P. Williams, The Biological Chemistry of the Elements – The Inorganic Chemistry of Life, Claderon Press, Oxford, 1991. [2] C. Oldham, Carboxylates, Squarates and Related Species, in: G. Wilkinson (Ed.), Comprehensive Coordination Chemistry, Pergamon Press, Oxford, 1987. [3] P. Zhou, D. OHagan, U. Mocek, Z. Zeng, L.-D. Yuen, T. Frenzel, C.J. Unkefer, J.M. Beale, H.G. Floss, J. Am. Chem. Soc. 111 (1989) 7274. [4] O. Geiger, H. Go¨risch, Biochem. J. 261 (1989) 415. [5] U. Brand, H. Varenkamp, Inorg. Chem. 34 (1995) 3285. [6] T.A. Zevaco, H. Go¨rls, E. Dinjus, Inorg. Chim. Acta 269 (1998) 283.
1093
[7] N. Okabe, Y. Muranishi, Acta Cryst. E59 (2003) m244–m246. [8] Synthesis of cis-Bis(quinoline-2-carboxylato) bis imidazole zinc(II): Quinoline-2-carboxylic acid (0.069 g, 0.34 mmol) and imidazole (0.058 g, 0.86 mmol) were dissolved in 30 cm3 of DMF and the resulted solution was added to the solution of Zn(ClO4)2 Æ 6H2O (0.064 g, 0.17 mmol) in DMF. After three days the colorless crystals were obtained. Yield: 62%. Anal. Calc. For C26H20N6O4 Zn: C, 57.2; H, 3.7; N, 15.4. Found: C, 57.3; H, 3.6; N, 15.5%. IR (KBr disk) cm 1 : 3436 m, 3101 m, 3014 m, 2919 m, 2824 m, 2776 m, 2685 m, 2624 m, 1618 vs, 1595 s, 1563 s, 1544 s, 1507 w, 1595 w, 1463 s, 1430 w, 1395 vs, 1273 s, 1345 w, 1356 w, 1327 w, 1295 vw, 1259 w, 1216 vw, 1204 vw, 1179 w, 1149 m, 1094 m, 1067 s, 959 w, 942 w, 896 s, 857 m, 873 s, 803 vs, 778 vs, 755 s, 742 m, 664 s, 635 m, 623 m, 604 m, 521 w, 500 w.Safety note: Perchlorates are potentially explosive. Although we have experienced no accidents so far, all compounds containing perchlorate should be handled with care and in small quantities. [9] Preliminary examination and intensity data collections were carried out on a Xcalibur PX diffractometer with graphite-monochromated Mo Ka radiation. All data were corrected for Lorentz, polarization and absorption effects. Data reduction and analysis were carried out with the Xcalibur PX software. The structures were solved by direct methods using SHELXS-97 program and refined using full-matrix least-squares on all F2 data using SHELXL-97 program. All nonhydrogen atoms were refined anisotropically and hydrogen atoms were included in calculated positions with isotropic thermal parameters. [10] Crystal data Zn(quin-2-c)2(Him)2:C26H20N6O4 Zn. Mr = 545.85 g mol 1; Monoclinic system, P21/c space group with ˚ , b = 106.32(3)(); a = 17.924(4), b = 39.259(7), c = 13.970(3) A ˚ 3; Z = 16; Dcalc 1.537 g cm-3; T = 100(2) K; Crystal V = 9434(3) A size = 0.40 · 0.25 · 0.14 mm; Reflections collected = 136551; Reflections unique = 19395 [Rint = 0.0550]; R indices [I > 2r(I)] R1 = 0.0855, wR2 = 0.1784, S = 1.209. [11] C. Janiak, J. Chem. Soc., Dalton Trans. (2000) 3885. [12] A.G. Orpen, L. Brammer, F.H. Allen, O. Kennard, D.G. Watson, R. Taylor, J. Chem. Soc., Dalton Trans. (Suppl.) (1989). [13] G.B. Deacon, R.J. Phillips, Coord. Chem. Rev. 33 (1980) 227. [14] (a) S.T. Warzeska, F. Micciche´, M.Ch. Mimmi, E. Bouwman, H. Kooijman, A.L. Spek, J. Reedijk, J. Chem. Soc., Dalton Trans. (2001) 3507; (b) L.S. Erre, G. Micera, F. Cariati, G. Ciani, A. Sironi, H. Kozłowski, J. Baranowski, J. Chem. Soc., Dalton Trans. (1988) 363; (c) D. Dobrzyn´ska, B.L. Jerzykiewicz, M. Duczmal, Polyhedron 24 (2005) 407.
3D supramolecular network constructed by intermolecular interactions in mixed ligand complex of zinc Danuta Dobrzyn´ska a
a,*
, Tadeusz Lis b, Lucjan B. Jerzykiewicz
b
Faculty of Chemistry, Wrocław University of Technology, Wybrze_ze Wyspian´skiego 27, 50-370 Wrocław, Poland b Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland Received 22 June 2005; accepted 7 September 2005 Available online 19 October 2005
Abstract New complex [Zn(quin-2-c)2(Him)2] (quin-2-c = quinoline-2-carboxylate ion, Him = imidazole) was synthesized by self assembly and its structure was determined by X-ray analysis. The compound crystallizes in P21/c space group. Four independent molecules of complex are present in the structure. Strong hydrogen bonds create three different 1D chains which are collected in two different layers. The alternately packed layers form the 3D supramolecular structure. The interchain and interlayer contacts are of the C–H O, p p and C– H p type. The influence of strong hydrogen bond on the vibrational characteristics of the monodentately coordinated carboxylate group in zinc complexes with quin-2-c ion is discussed. 2005 Elsevier B.V. All rights reserved. Keywords: Zinc complex; Crystal structure; Supramolecular network; Hydrogen bonds; Infrared spectra
Carboxylates are efficient catalysts in the biological and chemical processes [1]. The carboxylate group offers a variety of coordination modes and many types of complexes are known [2]. The need for characterization of the metal enzyme centers as well as the searches for new catalytic or magnetic materials causes an incessant interest in carboxylate chemistry. Quinoline-2-carboxylic acid is the biological compound involved in the metabolism of tryptophan [3]. It is a strong chelator providing the donor set similar to that responsible for binding metal ion in PQQ cofactor of quinoprotein family [4]. To date three zinc complexes with quin-2-c ion have been obtained and structurally characterized: [Zn(MEDA)(quin-2-c)] [5] (MEDA = N-(2-mercaptoethyl)picolylamine), [Zn(quin-2-c)2(1-Meim)2] [6] and [Zn(quin-2-c)2(H2O)] [7]. In these complexes, quin-2-c ion binds in a N,O chelate mode and the metal environment mimics the zinc enzyme centers. In the crystals of the mentioned compounds, strong hydrogen bonds and *
Corresponding author. Tel.: +48 71 320 3909; fax: +48 71 328 4330. E-mail address: [email protected] (D. Dobrzyn´ska).
1387-7003/$ - see front matter 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2005.09.009
weak intermolecular interactions of the C–H O, C– H p and p p type lead to the formations of 2D and 3D supramolecular frameworks. As a continuation of our interest in quinoline-2-carboxylates, we have synthesized [Zn(quin-2-c)2(Him)2] and studied its crystal structure. The significant differences in the hydrogen bonding systems in [Zn(quin-2-c)2(1-Meim)2], [Zn(quin-2-c)2(H2O)] and [Zn(quin-2-c)2(Him)2] are expressively reflected in the vibrational characteristics of the monodentate carboxylate group. cis-Bis(quinoline-2-carboxylato) bis imidazole zinc(II) was obtained from the reaction of Zn(ClO4)2 Æ 6H2O with a twofold excess quinoline-2-carboxylic acid and five equivalents of imidazole in the form of the single crystals. Crystals are air stable and have very limited solubility in common organic solvents [8]. The crystal structure of the complex was determined by single-crystal X-ray diffraction [9,10]. In the crystal of [Zn(quin-2-c)2(Him)2], four independent molecules of the complex have been found (a, b, c and d). A drawing of the molecular structure (Fig. 1) represents the molecule of the title complex.
D. Dobrzyn´ska et al. / Inorganic Chemistry Communications 8 (2005) 1090–1093
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Table 2 ˚ ), () Hydrogen bonds for Zn(quin-2-c)2 (Him) (A D–H A
d(D–H) d(H A) d(D A) \(DHA) (i)
N(22)–H(22) . . . O(12) N(22A)–H(22B) . . . O(2A)(ii) N(22B)–H(22C) . . . O(2C) N(22C)–H(22D) . . . O(2B)(iii) N(32)–H(32) . . . O(2)(iv) N(32A)–H(32B) . . . O(12A)(v) N(32B)–H(32C) . . . O(12C)(vi) N(32C)–H(32D) . . . O(12B) C(9A)–H(9AA) . . . O(11A) C(32A)–H(32B) . . . O(2C)(vii) C(9)–H(9A) . . . O(11) C(9B)–H(9BA) . . . O(11B) C(22B)–H(22C) . . . O(12A)(viii) C(19)–H(19A) . . . O(1) C(19A)–H(19B) . . . O(1A) C(19B)–H(19C) . . . O(1B) C(19C)–H(19D) . . . O(1C) C(9C)–H(9CA) . . . O(11C) C(22)–H(22A) . . . O(2B)(ix) C(22C)–H(22D) . . . O(12)(viii) Fig. 1. The molecular structure of the title complex (a) with the atom numbering scheme. The displacement ellipsoids are drawn at the 50% probability level.
The selected bond distances and angles for a, b, c and d are collected in Table 1. Table 2 lists the hydrogen bonds of N–H O and C–H O type. The geometry of the molecules a, b, c and d is the same but the molecular parameters display significant differences (see Table 1). The Zn2+ ion is six coordinated with the O2N4 donor set. The quin-2-c ion binds to zinc in a chelate mode, through the carboxylate O atom and the quinoline N atom. The carboxylate group is monodentate. The chelate rings are almost coplanar with the quinoline rings, the medium angle between quinoline
Table 1 ˚ ) and angles () for Zn(quin-2-c)2 (Him)2 Selected bond lengths (A Bond distances Zn(1)–O(11) Zn(1)–O(1) Zn(1)–N(21) Zn(1)–N(31) Zn(1)–N(1) Zn(1)–N(11)
a 2.047(3) 2.048(3) 2.109(4) 2.117(4) 2.329(4) 2.375(4)
b 2.030(3) 2.052(3) 2.115(4) 2.131(4) 2.293(4) 2.418(4)
2.014(3) 2.045(3) 2.104(4) 2.133(4) 2.353(4) 2.354(4)
2.020(3) 2.043(3) 2.088(4) 2.135(4) 2.399(4) 2.399(4)
Bond angles O(11)–Zn(1)–N(21) O(1)–Zn(1)–N(21) O(11)–Zn(1)–N(31) O(1)–Zn(1)–N(31) N(21)–Zn(1)–N(31) O(11)–Zn(1)–N(1) O(1)–Zn(1)–N(1) N(21)–Zn(1)–N(1) O(11)–Zn(1)–N(11) O(1)–Zn(1)–N(11) N(31)–Zn(1)–N(11) N(1)–Zn(1)–N(11)
95.85(15) 92.84(15) 91.63(15) 95.70(15) 90.56(16) 96.64(14) 76.64(14) 85.45(15) 75.43(14) 96.36(14) 85.61(15) 99.52(14)
95.15(12) 95.42(13) 90.92(13) 96.47(12) 89.66(14) 96.39(12) 76.38(12) 89.47(14) 74.99(11) 95.65(12) 81.43(13) 100.64(13)
96.10(14) 92.21(14) 93.68(14) 95.01(14) 89.92(15) 96.62(14) 75.62(14) 83.78(15) 76.42(13) 95.55(13) 88.15(14) 99.36(13)
96.22(15) 91.13(14) 94.64(14) 95.79(14) 91.01(15) 95.06(14) 75.10(13) 84.40(15) 76.86(14) 96.18(14) 86.95(14) 98.73(14)
c
d
0.88 0.88 0.88 0.88 0.88 0.88 0.88 0.88 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95 0.95
1.85 1.85 1.85 1.85 1.85 1.89 1.87 1.85 2.20 2.44 2.23 2.27 2.55 2.28 2.33 2.26 2.24 2.27 2.52 2.49
2.728(6) 2.728(5) 2.722(6) 2.723(6) 2.722(6) 2.767(5) 2.733(5) 2.726(6) 3.078(5) 3.164(7) 3.107(7) 3.141(6) 3.186(7) 3.160(7) 3.208(5) 3.133(6) 3.113(6) 3.147(6) 3.196(7) 3.186(7)
172 171 169 168 170 172 168 174 152 133 154 152 124 154 153 152 152 153 128 130
Symmetry transformations used to generate equivalent atoms: (i) x, y, z + 2; (ii) x, y 1/2, z 1/2; (iii) x, y, z + 1; (iv) 4 x, y, z + 1; (v) x, y 1/2, z 3/2; (vi) 6 x, y, z 1; (vii) x 1, y 1/2, z 3/2; (viii) x + 1, y, z; (ix) x + 1, y, z + 1.
rings in a, b, c and d equals 113.8(1). Two molecules of imidazole connected with zinc by aromatic nitrogen atoms are located in cis position. The medium value of Zn–NHim ˚ , is very close to that found for distance, 2.116(4) A [Zn(quin-2-c)2(1-Meim)2] [6] and is a little longer than the ˚) typical value observed for octahedral complexes (2.084 A [11]. Zinc–oxygen bond lengths in the studied complex are close to the literature data [5–7,11]. The zinc–quinoline ˚ nitrogen distances in a, b, c and d are very long (2.354(4) A – medium value) when compared with those observed for other complexes of Zn with quin-2-c ion as well as in the octahedral complexes of zinc with pyridine ligands ˚ ) [11]. The geometry around zinc ion is severely (2.111 A distorted. The bite angle of the chelating ligand is very small in the studied compound. Its medium value equals 75.93(4), whereas the relevant values are 79.5 and 78.33 for [Zn(quin-2-c)2(H2O)] [7] and 77.9 for [Zn(quin-2-c)2(1-Meim)2] [6]. The intramolecular hydrogen bond of the C–H O type stabilizes the molecules of a, b, c and d, see Table 2. Various intermolecular interactions organize the supramolecular structure of the crystal. The strong hydrogen
Fig. 2. Chain of molecules of [Zn(quin-2-c)2(Him)2] connected by strong hydrogen bonds extending along c-axis.
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bonds of the N–H O type (Table 2) create the 1D chains propagating along the crystallographic c-axis, Fig. 2. Three different chains can be distinguished: the first made of molecules a, the second built of molecules b and third comprising alternately positioned molecules c and d. The chains are collected in layers, Fig. 3. Two former chains are alternately packed in layer A, while layer B is made of the latter type of chains. Layers A and B are lo-
Fig. 3. Packing in the crystal of [Zn(quin-2-c)2(Him)2] viewed along the caxis. Layers A contain two types of chains, one made of a and second made of b. Layers B contain one type of chain, made of c and d. Dotted lines indicate stacking interactions. Atoms participating in the interlayer C–H O bonds are marked as balls.
˚ , d^ = 3.557 A ˚ ) and C–H p Fig. 4. p p contacts (Cg Cg = 3.738 A ˚, interactions between molecules b and d (a: d(C–H Cg) = 3.443(6) A ˚ , \(C–H Cg) = 174.5 ; b: d(C–H Cg) = 3.608(6) A ˚, d(H Cg) = 2.495 A ˚ , \(C–H Cg) = 162.0). Hydrogen atoms particid(H Cg) = 2.693 A pating in C–H p interactions with other neighbors are indicated.
cated alternately and create the 3D structure. The interchain interactions within layers are of the offset p p type [12]. The interlayer p p interactions are accompanied by C–H O hydrogen bonds and C–H p contacts, Figs. 3 and 4. The Dm(COO) = mas(COO) ms(COO) value which is commonly used in diagnosing the nature of carboxylate coordination follows the order Dmmonodentate > Dmionic Dmbridging > Dmchelate [13]. However, it is known that strong hydrogen bonding to the oxygen atom, not coordinated to the metal ion, in complexes with monodentate carboxylate group decreases the Dm value; this fact is very often neglected. To show the magnitude of the changes in D(COO) value caused by strong hydrogen bonding, we have compared the vibrational and structural characteristics of carboxylate group in [Zn(quin-2-c)2(Him)2] and [Zn(quin-2-c)2(1-Meim)2] (Table 3). In both compounds, the COO group of quin-2-c ligand binds to zinc in monodentate mode and the donor sets around the Zn2+ ions are the same (N4O2). The secondary ligands, imidazole and 1-methylimidazole, also coordinate to zinc in the same manner, through the aromatic (N3) nitrogen atom. In the crystal of [Zn(quin-2-c)2(Him)2], the strong hydrogen bridges of N–H O type are observed, whereas in [Zn(quin-2-c)2(1-Meim)2] only weak C–H O interactions are found. The Dm found for the former compound (223 cm 1) is smaller by 53 cm 1 than that observed for the latter complex (276 cm 1). According to the general rule, this value is characteristic of carboxylate bridging mode. The Dm value corresponding to the monodentate carboxylate group in [Zn(quin-2-c)2 (H2O)] is also significantly smaller than expected, and equals 240 cm 1. In this complex, strong intermolecular hydrogen bond between the coordinated water molecule and the carboxylate oxygen atom has been found (Table 3). Such low values of Dm have been reported for other monodentate carboxylates with C@O group involved in strong hydrogen bond [14] in all these cases the results of the X-ray analysis allowed to assign unambiguously the binding mode of carboxylate group. In conclusion, the new mixed ligand complex of zinc has been obtained by self assembly. The carboxylate ligands and imidazole molecules complete the strongly distorted octahedral coordination sphere around Zn2+ ion in cis configuration. In the crystal, four independent molecules are found. The title complex forms the supramolecular structure due to a variety of intermolecular interactions. Strong
Table 3 Comparison of vibrational and structural data for [Zn(quin-2-c)2 (Him)2], [Zn(quin-2-c)2 (1-Meim)2] and [Zn(quin-2-c)2 (H2O)] ˚) ˚) Compound mas(COO) (cm 1) ms(COO) (cm 1) Dm(COO) (cm 1) rC-O(M) (A rC@O (A [Zn(quin-2-c)2(Him)2] [Zn(quin-2-c)2(1-Meim)2]b [Zn(quin-2-c)2(H2O)]c a b c
Medium value. Ref. [6]. Ref. [7].
1618 1642 1630
1395 1366 1390
223 276 240
a
1.242 1.227 1.226a
a
1.254 1.273 1.270a
Hydrogen bond N–H O C–H O O–H O
D. Dobrzyn´ska et al. / Inorganic Chemistry Communications 8 (2005) 1090–1093
intermolecular hydrogen bonds create three types of 1D chains. The chains are arranged in two different layers which are packed alternately into 3D structure. The two latter supramolecular motifs result from the C–H O, C– H p and p p type interactions. Strong hydrogen bonds severely influence the vibrational characteristics of the carboxylate group. It is shown that the determination of the type of coordination of the carboxylate group cannot be made on the basis of their IR spectra only. Appendix A. Supplementary data Crystallographic data for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Center as supplementary publication No. CCDC 271897. Copies of the data can be obtained free of charge from CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44 1223 336 033; e-mail: [email protected]). Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.inoche.2005.09.009. References [1] (a) S. Kiani, A. Tapper, J.R. Staples, P. Stavropoulos, J. Am. Chem. Soc. 122 (2000) 7503; (b) J.J.R. Frau´sto da Silva, R.J.P. Williams, The Biological Chemistry of the Elements – The Inorganic Chemistry of Life, Claderon Press, Oxford, 1991. [2] C. Oldham, Carboxylates, Squarates and Related Species, in: G. Wilkinson (Ed.), Comprehensive Coordination Chemistry, Pergamon Press, Oxford, 1987. [3] P. Zhou, D. OHagan, U. Mocek, Z. Zeng, L.-D. Yuen, T. Frenzel, C.J. Unkefer, J.M. Beale, H.G. Floss, J. Am. Chem. Soc. 111 (1989) 7274. [4] O. Geiger, H. Go¨risch, Biochem. J. 261 (1989) 415. [5] U. Brand, H. Varenkamp, Inorg. Chem. 34 (1995) 3285. [6] T.A. Zevaco, H. Go¨rls, E. Dinjus, Inorg. Chim. Acta 269 (1998) 283.
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[7] N. Okabe, Y. Muranishi, Acta Cryst. E59 (2003) m244–m246. [8] Synthesis of cis-Bis(quinoline-2-carboxylato) bis imidazole zinc(II): Quinoline-2-carboxylic acid (0.069 g, 0.34 mmol) and imidazole (0.058 g, 0.86 mmol) were dissolved in 30 cm3 of DMF and the resulted solution was added to the solution of Zn(ClO4)2 Æ 6H2O (0.064 g, 0.17 mmol) in DMF. After three days the colorless crystals were obtained. Yield: 62%. Anal. Calc. For C26H20N6O4 Zn: C, 57.2; H, 3.7; N, 15.4. Found: C, 57.3; H, 3.6; N, 15.5%. IR (KBr disk) cm 1 : 3436 m, 3101 m, 3014 m, 2919 m, 2824 m, 2776 m, 2685 m, 2624 m, 1618 vs, 1595 s, 1563 s, 1544 s, 1507 w, 1595 w, 1463 s, 1430 w, 1395 vs, 1273 s, 1345 w, 1356 w, 1327 w, 1295 vw, 1259 w, 1216 vw, 1204 vw, 1179 w, 1149 m, 1094 m, 1067 s, 959 w, 942 w, 896 s, 857 m, 873 s, 803 vs, 778 vs, 755 s, 742 m, 664 s, 635 m, 623 m, 604 m, 521 w, 500 w.Safety note: Perchlorates are potentially explosive. Although we have experienced no accidents so far, all compounds containing perchlorate should be handled with care and in small quantities. [9] Preliminary examination and intensity data collections were carried out on a Xcalibur PX diffractometer with graphite-monochromated Mo Ka radiation. All data were corrected for Lorentz, polarization and absorption effects. Data reduction and analysis were carried out with the Xcalibur PX software. The structures were solved by direct methods using SHELXS-97 program and refined using full-matrix least-squares on all F2 data using SHELXL-97 program. All nonhydrogen atoms were refined anisotropically and hydrogen atoms were included in calculated positions with isotropic thermal parameters. [10] Crystal data Zn(quin-2-c)2(Him)2:C26H20N6O4 Zn. Mr = 545.85 g mol 1; Monoclinic system, P21/c space group with ˚ , b = 106.32(3)(); a = 17.924(4), b = 39.259(7), c = 13.970(3) A ˚ 3; Z = 16; Dcalc 1.537 g cm-3; T = 100(2) K; Crystal V = 9434(3) A size = 0.40 · 0.25 · 0.14 mm; Reflections collected = 136551; Reflections unique = 19395 [Rint = 0.0550]; R indices [I > 2r(I)] R1 = 0.0855, wR2 = 0.1784, S = 1.209. [11] C. Janiak, J. Chem. Soc., Dalton Trans. (2000) 3885. [12] A.G. Orpen, L. Brammer, F.H. Allen, O. Kennard, D.G. Watson, R. Taylor, J. Chem. Soc., Dalton Trans. (Suppl.) (1989). [13] G.B. Deacon, R.J. Phillips, Coord. Chem. Rev. 33 (1980) 227. [14] (a) S.T. Warzeska, F. Micciche´, M.Ch. Mimmi, E. Bouwman, H. Kooijman, A.L. Spek, J. Reedijk, J. Chem. Soc., Dalton Trans. (2001) 3507; (b) L.S. Erre, G. Micera, F. Cariati, G. Ciani, A. Sironi, H. Kozłowski, J. Baranowski, J. Chem. Soc., Dalton Trans. (1988) 363; (c) D. Dobrzyn´ska, B.L. Jerzykiewicz, M. Duczmal, Polyhedron 24 (2005) 407.