Perplexing Coordination Behaviour of Potentially Bridging Bipyridyl-Type Ligands in the Coordination Chemistry of Zinc and Cadmium 1,1-Dithiolate Compounds

Abstract

Abstract:The X-ray structural chemistry of zinc and cadmium 1,1-dithiolates (for example, xanthate, dithiophosphate and dithiocarbamate) with potentially bridging bipyridyl-type ligands (for example, 4,4 -bipyridine) is reviewed. For zinc, the xanthates and dithiophosphates uniformly form one-dimensional coordination polymers, whereas the zinc dithiocarbamates are always zero-dimensional, reflecting the exceptional chelating ability of dithiocarbamate ligands compared with xanthates and dithiophosphates. For cadmium, one-dimensional coordination polymers are usually found, reflecting the larger size of cadmium compared with zinc, but zero-dimensional aggregates are sometimes found. Steric effects associated with the 1,1-dithiolate-bound R groups are shown to influence supramolecular aggregation and, when formed, polymer topology in order to reduce steric hindrance; the nature of the bipyridyl-type ligand can also be influential. For the dithiocarbamates of both zinc and cadmium, in instances where the dithiocarbamate ligand is functionalised with hydrogen bonding potential, extended supramolecular architectures are often formed via hydrogen bonding interactions. Of particular interest is the observation that the bipyridyl-type ligands do not always bridge zinc or cadmium 1,1-dithiolates, being monodentate instead, often in the presence of hydrogen bonding. Thus, hydroxyl-O-H . . . N(pyridyl) hydrogen bonds are sometimes formed in preference to M←N(pyridyl) coordinate-bonds, suggesting a competition between the two modes of association.

Crystal structure of catena-[(bis(O,O′-diethyl dithiophosphato-S,S′)-μ2-1,2-bis(3-pyridylmethylene)hydrazine-N,N′)zinc(II)], {C20H30N4O4P2S4Zn}n

“…The isomeric, potentially bridging molecules, 1,2bis(n-pyridylmethylene)hydrazine, n-NC5H4C(H)=N-N=C(H)C5H4N-n, often referred to as the n-pyridylaldazines (n-PyAld), have revealed interesting monodentate modes of coordination in their adducts with zinc-triad 1,1-dithiolates [5]. For example, when the metal node is zinc complexed to dithiocarbamate ( − S 2 CN(R)R′) and the ligand is 4-PyAld, monodentate coordination of 4-PyAld is observed in mononuclear Zn[S 2 CN(iPr)CH 2 CH 2 OH] 2 (4-PyAld) with five-coordinate zinc(II) [6]; the non-coordinating pyridyl-nitrogen atom engages in hydroxy-O-H· · · N(pyridyl) hydrogen bonding.…”

Crystal structure of catena-poly[{μ2-1,5-bis(diphenylphosphanyl)pentane-κ2 P:P′}dichloridocadmium(II)], C29H30CdCl2P2

“…Prior to the most recent study [5], the only other polymeric structure was that formed between CdCl 2 and (R,R)-trans-4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-dioxalane [8]. The title one-dimensional coordination polymer [CdCl 2 (dppp)]n, (I), where dppp is 1,5-bis (diphenylphosphino)propane, was determined in continuation of on-going studies of cadmium coordination polymers [5,[9][10][11]. The asymmetric unit of (I) is shown in the top view of the figure (70% probability displacement ellipsoids; the unlabelled dppp molecule is related by the symmetry operation (i) x, −1 + y, z) and comprises a cadmium(II), two chlorido ligands and a full dppp ligand.…”

Exploring the Topological Landscape Exhibited by Binary Zinc-triad 1,1-dithiolates

“…In short, the bulkier the R substituent, the less likely it is that supramolecular aggregation will occur. This concept is now well established in the structural chemistry of main group element 1,1-dithiolates [17,[40][41][42] and in the structural chemistry of related organotin carboxylates [43][44][45], where bulky groups can disrupt [18,[46][47][48]. Further, it should be stressed that the nature of R, at least that present in the overwhelming majority of zinc-triad xanthate structures, does not exert a significant influence upon the electronic structure of the xanthate anion [49].…”

“…Crystals 2018, 8, x FOR PEER REVIEW 4 of 32 and in the structural chemistry of related organotin carboxylates [43][44][45], where bulky groups can disrupt secondary bonding interactions [18,[46][47][48]. Further, it should be stressed that the nature of R, at least that present in the overwhelming majority of zinc-triad xanthate structures, does not exert a significant influence upon the electronic structure of the xanthate anion [49].…”

“…is in a position orthogonal to the S-Hg-S vector so that the mercury atom has a (planar) T-shaped geometry; the two proximate intra-chain oxygen atoms are disposed well above the HgS3 plane and with Hg … O separations of 2 × 2.93 Å are not considered as significant bonding interactions [33]. Both P21 (12) (18), and Pentyl (19) [38]. With the exception of 15, the structures adopt the common motif A and with obvious voids in the structure when viewed normal to the plane of the array; congestion obviously increases with the size of the R substituent, especially in 17 and 18.…”