摘要:
Hydrogen bond directed crystal engineering of nickel complexes: the crystal structure of cis-bis(4- ethylthiosemicarbazide)nickel(II) terephthalate and the influence of metal geometry on supramolecular structure Andrew D. Burrows, Ross W. Harrington and Mary F. Mahon Department of Chemistry, University of Bath, Claverton Down, Bath, UK BA2 7AY. E-mail: a.d.burrows@bath.ac.uk Received 4th February 2000, Accepted 3rd April 2000, Published 18th April 2000 The single crystal X-ray structure of cis-bis(4-ethylthiosemicarbazide)nickel(II) terephthalate, 1, reveals that the cations and anions are linked into hydrogen-bonded chains via interactions between two hydrogen bond donors on the thiosemicarbazide ligands and two hydrogen bond acceptors on the terephthalate (DD:AA).In contrast to the structures of transbis(thiosemicarbazide)nickel(II) dicarboxylates, the DD motifs are derived from the amino NH bonds, and are comprised of one hydrogen bond donor from each ligand on the complex. Consequently, the supramolecular structure of 1 is different to those observed for trans-bis(thiosemicarbazide)nickel(II) dicarboxylates, and the cations and anions lie almost perpendicular to each other in the crystal structure. the principal hydrogen bonds that these would dominate supramolecular structures, and generally these interactions are observed. However, the observation of a structure, [Ni{SC(NH2)(NHNMe2)}2(OH2)2][terephthalate]·2H2O,7 in which these interactions are absent clearly suggests that the subsidiary hydrogen bonds cannot be ignored.Our previous studies of bis(thiosemicarbazide)metal dicarboxylates have employed cations of the type trans- [M(tsc)2]2+. Here we report the crystal structure of cis- [NiL12][terephthalate], 1, in which L1 is NHEtC(S)NHNH2, 4-ethylthiosemicarbazide. The cis orientation of the thiosemicarbazide ligands leads to the presence of two alternative DD motifs in the cation, and it is these that are involved in chain formation in the crystal structure. Introduction Over the past few years, two main strategies have emerged for the controlled inclusion of transition metal centres into solid state supramolecular structures. These involve either the use of coordinative bonds1 or of intermolecular interactions, and in this latter class the hydrogen bond has received most attention.2 There are a number of factors contributing to the prevalence of hydrogen bonding in crystal engineering studies—the interactions are relatively strong, they are directional, and hydrogen bonds are able to act in concert with each other, thus enhancing the strength of intermolecular interactions.3 Multiple hydrogen bonds can be employed as the basis for supramolecular coordination chemistry by using bifunctional ligands that contain both metal binding groups and a hydrogen bonding surface that is unaltered on coordination.4 Although a number of such ligands have been designed, prepared and used,5 there also exist simple, cheap, readily available ligands that fulfil the above criteria and can be exploited in this manner.One such ligand is thiosemicarbazide [NH2C(S)NHNH2, tsc] which, on bidentate coordination through sulfur and nitrogen, contains two parallel NH groups. These can act as hydrogen bond donors to a moiety containing two appropriately disposed hydrogen bond acceptors. We have previously reported the interaction between two hydrogen bond donors (DD) on a thiosemicarbazide ligand and two hydrogen bond acceptors (AA) on a carboxylate as the building blocks for hydrogen bonded polymers of the general formula [M(tsc)2][dicarboxylate] based on nickel6,7 or zinc.8 The cations and anions are generally linked into chains by the DD:AA motif, a relatively robust supramolecular synthon9,10 in which the two hydrogen bonds are strengthened both by attractive secondary interactions11 and by an ionic contribution. We introduced the terminology principal hydrogen bonds to describe those interactions within the DD:AA motif and subsidiary hydrogen bonds to describe the other hydrogen bonds present within the structure, such as those involved in linking the chains together.It might be expected from the relative strength of DOI: 10.1039/b000977f CrystEngComm, 2000, 12 Results and discussion Single crystals of cis-[NiL12][terephthalate] were prepared by mixing aqueous solutions of [NiL12][NO3]2 and sodium terephthalate. The asymmetric unit of 1 (Fig. 1) consists of a nickel centre, which is located on a special position with half-site occupancy, to which one 4-ethylthiosemicarbazide ligand is coordinated through the sulfur and amino nitrogen atoms, and in addition one half of a terephthalate anion.The remainder of the cation is generated by transformation through a two-fold rotation axis at 0, y, 1/4, whilst the remainder of the anion is generated by transformation through a two-fold rotation axis at 1/2, y, 1/4. Both rotation axes are intrinsic to the C2/c space group. The nickel geometry in 1 is distorted square planar with selected bond lengths and angles given in Table 1. The Ni– N bond lengths [1.917(3) Å] are slightly longer than those observed in [Ni{SC(NH2)(NHNH2)}2][terephthalate],6 2 [1.901(2) Å] and similar to those in [Ni{SC(NHMe)(NHNH2)}2][ terephthalate]·4H2O, 7 3 [1.911(2) Å], whereas the Ni–S distances are slightly shorter than those in both 2 and 3 [2.152(1) Å, cf.2.170(1) Å for 2, and 2.1773(7) Å for 3]. The thiosemicarbazide ring in 1 is almost completely planar, with the largest deviationTable 1 Selected bond lengths (Å) and angles (°) for 1a S(1)–C(1) C(1)–N(3) N(3)–C(2) 1.917(3) 2.1515(14) 1.425(4) 1.319(4) Ni(1)–N(1) Ni(1)–S(1) N(1)–N(2) C(1)–N(2) C(1)–N(2)–N(1) C(1)–N(3)–C(2) N(3)–C(1)–N(2) N(3)–C(1)–S(1) N(2)–C(1)–S(1) 89.9(2) 88.65(10) 178.53(7) 92.81(8) 97.90(13) 116.1(2) N(1)–Ni(1)–N(1)' N(1)–Ni(1)–S(1) N(1)–Ni(1)–S(1)' S(1)–Ni(1)–S(1)' C(1)–S(1)–Ni(1) N(2)–N(1)–Ni(1) a Symmetry operation used to generate primed atoms is –x, y, –z + 1/2.Fig. 1 The asymmetric unit present in the crystal structure of 1. Click image or here for a 3D view. from the ring generated by Ni(1), S(1), C(1), N(2) and N(1) being 0.010 Å, for N(1). In the anion, the carboxylates are twisted out of the plane of the aromatic ring, with the mean torsion angle around C(4)–C(7) being 19.8°. This twist facilitates the formation of hydrogen bonds between N(2)– H(2) and O(1), and N(3)–H(3) and O(2) (see below). In contrast to the other bis(thiosemicarbazide)nickel dicarboxylate complexes that have been structurally characterised, the ligands in 1 are arranged mutually cis. This orientation results in the presence of two new DD motifs, both of which contain one hydrogen bond donor from each ligand.These motifs have the directionality required to interact with the AA motifs of carboxylate groups and form principal hydrogen bonds (Fig. 2). Table 2 Hydrogen bond geometries in the crystal structure of 1 X–H···Y/° H···Y/Å X···Y/Å X–H···Y 166(3) 151(3) 168(4) 164(4) 2.00(3) 1.88(3) 2.12(3) Principal hydrogen bonds— N(1)–H(1A)···O(1) 2.827(4) 1.96(3) N(1)–H(1B)···O(2) 2.786(4) Subsidiary hydrogen bonds linking chains— N(2)–H(2)···O(1) 2.735(4) Subsidiary hydrogen bonds linking sheets— N(3)–H(3)···O(2) 2.925(4) 1.732(4) 1.316(4) 1.448(5) 118.0(3) 124.0(3) 120.7(3) 120.0(3) 119.3(2) Fig. 2 The potential DD motifs available in the cis-bis(4- ethylthiosemicarbazide)nickel(II) cation. The blue motif is potentially present in all bis(thiosemicarbazide)nickel(II) cations, whereas the red motif is generated by the cis orientation of the ligands. Details of the hydrogen bonding observed within the structure of 1 are given in Table 2.The cations and anions are linked by pairs of hydrogen bonds through DD:AA interactions, but it is the new DD motif formed as a consequence of the cis orientation of the thiosemicarbazides that is utilised in this structure. These principal hydrogen bonds, N(1)–H(1A)···O(1) and N(1)'– H(1B)'···O(2), lead to the formation of eight-membered 22 R (8)], and hydrogen-bonded rings [graph set notation12 consequently to infinite cation···anion···cation chains along the a axis (Fig. 3). Symmetry operation generating XH –x, y, 1/2 – z 1/2 – x, 1/2 – y, 1 – z x, –y, –1/2 + zFig.3 The formation of hydrogen-bonded sheets within the crystal structure of 1 generated by the cross linking of the cation···anion···cation chains. Click image or here to access a rotatable 3D representation. Fig. 4 The interactions of sheets within the crystal structure of 1, serving to generate the observed 3D structure. As a result of the difference between the principal hydrogen bonding motif in this structure and that observed in trans-bis(thiosemicarbazide)nickel(II) dicarboxylates, the formation of sheets and their subsequent linking into the 3D structure must also occur in a different manner. A hydrogen bond, N(2)–H(2)···O(1), serves to link the chains into sheets that lie parallel to the ac plane.These interactions lead to the formation of 10- and 24-membered rings [graph sets 2 2 4 R (10) and R44 (24)] (Fig. 3). The sheets are subsequently linked via a further, longer hydrogen bond interaction between the remaining amino hydrogen atom H(3), and O(2) to afford the overall 3D structure (Fig. 4). In 3 the cation···anion···cation chains are linked into sheets by N– H···O hydrogen bonds in which one of the amino NH protons acts as hydrogen bond donor. As in 1 this leads to the formation of 10-membered rings, with the generated graph sets [ 24 R (10) and R44 (30)] similar to those in 1 (Fig. 5). The major difference between the two structures is in the way in which these sheets link together to generate the 3D structure.In 1 this occurs through long N–H···O hydrogen bonds whereas in 3 the hydrogen bonds are mediated by included water molecules. The hydrogen bonding motif adopted in 1 has other important structural consequences. Involvement of H(3) in inter-sheet hydrogen bonding results in a change in orientation of the thioamino group so that the N(3)–H(3) bond is not parallel to the N(2)–H(2) bond (as it is in all the previously characterised trans-bis(thiosemicarbazide)nickel and -zinc dicarboxylates), but is rotated by approximately 180° around the C(1)–N(3) bond vector. This means that the cation, as observed, contains only two and not four potential DD groups. In addition, since the N(1)–H(1A) and N(1)–H(1B) bonds are not co-planar with the chelate ring, the cations and anions in 1 lie almost perpendicular to each other, in contrast to those in 2 which are essentially coplanar.In 3 the cations and anions linked by the principalTable 3 Crystallographic data for compound 1a C14H22N6NiO4S2 461.21 293(2) Monoclinic C2/c 12.102(6) 15.053(7) 12.451(11) 118.80(3) 1988(2) 41.219 1923 1754 [R(int) = 0.0105] R1 = 0.0430, wR2 = 0.1353 R1 = 0.0471, wR2 = 0.1580 Chemical formula Formula weight T/K Crystal system Space group a/Å b/Å c/Å b/° V/Å3 Zm/mm–1 Reflections collected Independent reflections Final R indices [I > 2 s(I)] R indices (all data) a Click here for full crystallographic data (CCDC no. 1350/18). hydrogen bonds are close to co-planarity, though since these chains are linked by N–H···O hydrogen bonds involving amino NH groups which are directed above and below the plane of the cation (defined by Ni, N and S) the angles between the planes of the cations and anions and that defined by the sheets are 71.3(1) and 58.8(1)° respectively.The structure of 1 demonstrates that the metal geometry adopted can affect the number and arrangement of multiple hydrogen bonding motifs, which in turn can have an important effect on the manner in which cations and anions interact to form chain structures. The generation of DD motifs solely through the relative orientation of hydrogen bonding ligands was unexpected, and has important consequences for hydrogen bond mediated crystal engineering as the foundation of such studies is underpinned by the robustness of the principal hydrogen bond interactions.The emergence of new motifs as a consequence of ligand orientation adds another dimension to already established variables such as tautomerisation and polymorphism which combine to make crystal engineering such a complex and fascinating challenge. We are currently investigating other dicarboxylates of the cis-[NiL12]2+ cation to determine how the new DD:AA motif observed in the structure of 1 is affected by change in the anion. Experimental Sodium terephthalate (0.027 g, 0.127 mmol) in water (3 cm3) was added to a solution of [NiL12][NO3]2 (0.050 g, 0.127 mmol) in water (3 cm3). After standing for 72 h at room temperature, red crystals of 1 formed which were suitable for X-ray analysis.(Found: C, 36.2; N, 18.2; H, 4.77%) n /cm–1 1661m (NH 4.72%. C14H22N6NiO4S2 requires C, 36.5; N, 18.2; H, max/cm–1 3193w (NH), 1549s, 1350s (CO2); dmax 2). The crystal structure of 1 was determined on a CAD4 automatic four-circle diffractometer using Mo-Ka radiation ( l = 0.71069 Å). Details of the crystal structure are given in Table 3. The data was corrected for Lorentz and polarisation but not for absorption. The structure was solved using SHELX8613 and refined using SHELXL93.14 In the final least squares cycles all atoms were allowed to vibrate anisotropically. Hydrogen atoms were included at calculated positions on carbon centres.All hydrogens Fig. 5 Rotatable Chime representation of the hydrogen-bonded sheets present in the crystal structure of 3. Click image or here for a 3D view. attached to nitrogen atoms were readily located and refined at a fixed distance of 0.89 Å from the relevant parent atoms. The asymmetric unit of 1 (Fig. 1) along with the labelling scheme used was produced using ORTEX.15 References 1 A. J. Blake, N. R. Champness, P. Hubberstey, W.-S. Li, M. A. Withersby and M. Schröder, Coord. Chem. Rev., 1999, 183, 117; L. Carlucci, G. Ciani and D. M. Proserpio, Angew. Chem., Int. Ed., 1999, 38, 3488; O. M. Yaghi, H. L. Li, C. Davis, D. Richardson and T. L. Groy, Acc. Chem. Res., 1998, 31, 474; M.-L. Tong, S.- L. Zheng and X.-M. Chen, Chem.Commun., 1999, 561; O. R. Evans, R.-G. Xiong, Z. Liang, G. K. Wong and W. Lin, Angew. Chem., Int. Ed., 1999, 38, 536; A. S. Batsanov, P. Hubberstey, C. E. Russell and P. H. Walton, J. Chem. Soc., Dalton Trans., 1997, 2667. 2 D. Braga, F. Grepioni and G. R. Desiraju, J. Organomet. Chem., 1997, 548, 33; S. B. Copp, K. T. Holman, J. O. S Sangster, S. Subramanian and M. J. Zaworotko, J. Chem. Soc., Dalton Trans., 1995, 2223;S. Subramanian and M. J. Zaworotko, Coord. Chem. Rev., 1994, 137, 357. 3 D. Philp and J. F. Stoddart, Angew. Chem. Int., Ed. Engl., 1996, 35, 1154; C. B. Aakeröy, Acta Crystallogr., Sect. B, 1997, B53, 569; G. M. Whitesides, E. E. Simanek, J. P. Mathias, C. T. Seto, D. N. Chin, M. Mammen and D. M. Gordan, Acc. Chem.Res., 1995, 28, 37. 4 A. D. Burrows, C.-W. Chan, M. M. Chowdhry, J. E. McGrady and D. M. P. Mingos, Chem. Soc. Rev., 1995, 24, 329. 5 P. V. Bernhardt, Inorg. Chem., 1999, 38, 3481; C. L. Schauer, E. Matwey, F. W. Fowler and J. W. Lauher, J. Am. Chem. Soc., 1997, 119, 10245; C. Janiak, S. Deblon, H.-P. Wu, M. J. Kolm, P. Klüfers, H. Piotrowski and P. Mayer, Eur. J. Inorg. Chem., 1999, 1507; M. Mitsumi, J. Toyoda and K. Nakasuji, Inorg. Chem., 1995, 34, 3367; C. B. Aakeröy, A. M. Beatty and D. S. Leinen, J. Am. Chem. Soc., 1998, 120, 7383; M. M. Chowdhry, D. M. P. Mingos, A. J. P. White and D. J. Williams, Chem. Commun., 1996, 899. 6 A. D. Burrows, D. M. P. Mingos, A. J. P. White and D. J. Williams, Chem. Commun., 1996, 97. 7 M. T. Allen, A. D. Burrows and M. F. Mahon, J. Chem. Soc., Dalton Trans., 1999, 215. 8 A. D. Burrows, S. Menzer, D. M. P. Mingos, A. J. P. White and D. J. Williams, J. Chem. Soc., Dalton Trans., 1997, 4237. 9 D. Papoutsakis, J. P. Kirby, J. E. Jackson and D. G. Nocera, Chem. Eur. J., 1999, 5, 1474. 10 V. R. Thalladi, B. S. Goud, V. J. Hoy, F. H. Allen, J. A. K. Howard and G. R. Desiraju, Chem. Commun., 1996, 401. 11 J. Pranata, S. G. Wierschke and W. L. Jorgensen, J. Am. Chem. Soc., 1991, 113, 2810. 12 J. Bernstein, R. E. Davis, L. Shimoni and N.-L. Chang, Angew. Chem., Int. Ed. Engl., 1995, 34, 1555. 13 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, A46, 467. 14 G. M. Sheldrick, SHELXL, a computer program for crystal structure refinement, University of Göttingen, 1993. 15 P. McArdle, J. Appl. Crystallogr., 1995, 28, 65. CrystEngComm © The Royal Society of Chemistry 2000
ISSN:1466-8033
DOI:10.1039/b000977f
出版商:RSC
年代:2000
数据来源: RSC