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

Interligand Charge-Transfer Processes in Zinc Complexes

Electron donor–acceptor (EDA) complexes are characterized by charge-transfer (CT) processes between electron-rich and electron-poor counterparts, typically resulting in a new absorption band at a higher wavelength. In this paper, we report a series of novel 2,6-di(imino)pyridine ligands with different electron-rich aromatic substituents and their 1:2 (metal/ligand) complexes with zinc(II) in which the formation of a CT species is promoted by the metal ion coordination. The absorption properties of these complexes were studied, showing the presence of a CT absorption band only in the case of aromatic substituents with donor groups. The nature of EDA interaction was confirmed by crystallographic studies, which disclose the electron-poor and electron-rich moieties involved in the CT process. These moieties mutually belong to both the ligands and are forced into a favorable spatial arrangement by the coordinative preferences of the metal ion.

Unusual {···HNC2O···HCnO}, n = 1 or 2, synthons predominate in the molecular packing of the one-dimensional coordination polymers, {Cd[S2P(OR)2]2(3LH2)}n, for R = Me and Et, but are precluded when R = i-Pr; 3LH2 = N,N′-bis(3-pyridylmethyl)oxalamide

Linear, one-dimensional coordination polymers, {Cd[S2P(OR)2]2(3LH2)}n, for R = Me (1), Et (2) and i-Pr (3) have been fully characterised by a variety of physiochemical, spectroscopic, crystallographic and computational techniques. Two-dimensional...

I⋯N halogen bonding in 1 : 1 co-crystals formed between 1,4-diiodotetrafluorobenzene and the isomeric n-pyridinealdazines (n = 2, 3 and 4): assessment of supramolecular association and influence upon solid-state photoluminescence properties

1 : 1 co-crystals formed between 1,4-diiodotetrafluorobenzene and each of the three isomeric n-pyridinealdazines (n = 2, 3 and 4), featuring I⋯N halogen bonding contacts within one-dimensional chains, are described.

The Coordination Chemistry of Imidomethanedithiolate Di-anions: A Structural Comparison with Their Dithiocarbamate Analogs

A review of the coordination chemistry along with the structural features of heavy element complexes of dithiocarbimate di-anions in the form of [(R)C=NCS2]2− for R = CN, alkyl, and aryl are described. This class of compound is far less studied compared with the well-explored dithiocarbamate mono-anions formulated as [R(R’)NCS2]− for R/R’ = H, alkyl, and aryl. The coordination chemistry of dithiocarbimate di-anions is dominated by a S,S-chelating mode; rare examples of alternative modes of coordination are evident. When comparisons are available, the structural motifs adopted by metal dithiocarbimate complexes match those found for their dithiocarbamate analogs, with only small, non-systematic variations in the M–S bond lengths.

Dithiocarbamate Complexes of Platinum Group Metals: Structural Aspects and Applications

The incorporation of dithiocarbamate ligands in the preparation of metal complexes is largely prompted by the versatility of this molecule. Fascinating coordination chemistry can be obtained from the study of such metal complexes ranging from their preparation, the solid-state properties, solution behavior as well as their applications as bioactive materials and luminescent compounds, to name a few. In this overview, the dithiocarbamate complexes of platinum-group elements form the focus of the discussion. The structural aspects of these complexes will be discussed based upon the intriguing findings obtained from their solid- (crystallographic) and solution-state (NMR) studies. At the end of this review, the applications of platinum-group metal complexes will be discussed.

On the Coordination Role of Pyridyl-Nitrogen in the Structural Chemistry of Pyridyl-Substituted Dithiocarbamate Ligands

A search of the Cambridge Structural Database was conducted for pyridyl-substituted dithiocarbamate ligands. This entailed molecules containing both an NCS2− residue and pyridyl group(s), in order to study their complexation behavior in their transition metal and main group element crystals, i.e., d- and p-block elements. In all, 73 different structures were identified with 30 distinct dithiocarbamate ligands. As a general observation, the structures of the transition metal dithiocarbamates resembled those of their non-pyridyl derivatives, there being no role for the pyridyl-nitrogen atom in coordination. While the same is true for many main group element dithiocarbamates, a far greater role for coordination of the pyridyl-nitrogen atoms was evident, in particular, for the heavier elements. The participation of pyridyl-nitrogen in coordination often leads to the formation of dimeric aggregates but also one-dimensional chains and two-dimensional arrays. Capricious behaviour in closely related species that adopted very different architectures is noted. Sometimes different molecules comprising the asymmetric-unit of a crystal behave differently. The foregoing suggests this to be an area in early development and is a fertile avenue for systematic research for probing further crystallization outcomes and for the rational generation of supramolecular architectures.

A Structural Survey of Poly-Functional Dithiocarbamate Ligands and the Aggregation Patterns They Sustain

An overview is presented of the crystal structures of transition metal, main group element, and lanthanide compounds containing poly-functional dithiocarbamate ligands, namely species containing two or more connected NCS2− residues. In all, there are 40 different ligands of this type that have been characterised crystallographically in their heavy-element compounds with up to six NCS2− residues; all are bridging. In most cases, the resulting aggregates are zero-dimensional, often di-nuclear, but aggregates of up to 36 metal (gold) atoms are noted. There are smaller numbers of one-, two-, and three-dimensional architectures sustained by poly-functional dithiocarbamate ligands in their respective crystals. The survey highlights the opportunities afforded by this generally under-studied class of ligand.

Crystal structure of tetrakis (N-(2-hydroxyethyl)-N-isopropylcarbamodithioato-κS,S′)-(μ2(2-(pyridin-4-yl)vinyl)pyridine-κN,N′)dicadmium(II), C36H58Cd2N6O4S8

C36H58Cd2N6O4S8, monoclinic, P21/c (no. 14), a = 7.82927(4) Å, b = 11.64209(5) Å, c = 26.2493(1) Å, β = 95.6985(4)°, V = 2380.775(18) Å3, Z = 2, R gt(F) = 0.0158, wR ref(F 2) = 0.0411, T = 100(2) K.

Crystal structure of catena{di-aqua-sodium-[N-(hydroxyethyl), N-isopropyl-dithiocarbamato]}n, [C6H16NNaO2S2]n

C6H16NNaO2S2, monoclinic, P21/c (no. 14), a = 13.2126(4) Å, b = 5.9418(1) Å, c = 14.6038(3) Å, β = 100.395(3)°, V = 1127.68(5) Å3, Z = 4, R gt(F) = 0.0287, wR ref(F 2) = 0.0788, T = 100(2) K.

A Survey of Supramolecular Aggregation Based on Main Group Element⋯Selenium Secondary Bonding Interactions—A Survey of the Crystallographic Literature

The results of a survey of the crystal structures of main group element compounds (M = tin, lead, arsenic, antimony, bismuth, and tellurium) for intermolecular M⋯Se secondary bonding interactions is presented. The identified M⋯Se interactions in 58 crystals can operate independent of conventional supramolecular synthons and can sustain zero-, one-, two, and, rarely, three-dimensional supramolecular architectures, which are shown to adopt a wide variety of topologies. The most popular architecture found in the crystals stabilized by M⋯Se interactions are one-dimensional chains, found in 50% of the structures, followed by zero-dimensional (38%). In the majority of structures, the metal center forms a single M⋯Se contact; however, examples having up to three M⋯Se contacts are evident. Up to about 25% of lead(II)-/selenium-containing crystals exhibit Pb⋯Se tetrel bonding, a percentage falling off to about 15% in bismuth analogs (that is, pnictogen bonding) and 10% or lower for the other cited elements.

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

C20H30N4O4P2S4Zn, triclinic, P1̄ (no. 2), a = 8.01840(1) Å, b = 8.4326(1) Å, c = 23.5086(2) Å, α = 80.478(1)°, β = 80.679(1)°, γ = 76.112(1)°, V = 1509.37(3) Å3, Z = 2, R gt(F) = 0.0449, wR ref(F 2) = 0.1182, T = 100(2) K.

Crystal structure of catena-[(bis(O,O′-diethyl dithiophosphato-S,S′)-μ2-1,2-bis(4-pyridylmethylene)hydrazine-N,N′)cadmium(II)], {C20H30CdN4O4P2S4}n

C20H30CdN4O4P2S4, triclinic, P1̄ (no. 2), a = 9.3353(2) Å, b = 9.7725(2) Å, c = 10.6884(2) Å, α = 63.153(2)°, β = 64.193(2)°, γ = 62.710(2)°, V = 740.43(3) Å3, Z = 1, R gt(F) = 0.0171, wR ref(F 2) = 0.0465, T = 100 K.

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

C29H30CdCl2P2, orthorhombic, Pna21 (no. 33), a = 15.84368(4) Å, b = 8.46281(2) Å, c = 20.88054(8) Å, V = 2799.705(14) Å3, Z = 4, R gt(F) = 0.0275, wR ref(F 2) = 0.0719, T = 100(2) K.

Crystal structure of catena-poly[(μ2-pyrazine-N,N′)-bis(O,O′-di-isopropyldithiophosphato-S,S′)cadmium(II) acetonitrile di-solvate], [C16H32CdN2O4P2S4⋅2(C2H3N)]n

C20H38CdN4O4P2S4, triclinic, P1̄ (no. 2), a = 9.6352(2) Å, b = 11.3986(2) Å, c = 14.8017(3) Å, α = 85.713(2)°, β = 89.877(2)°, γ = 86.048(2)°, V = 1617.23(6) Å3, Z = 2, R gt(F) = 0.0285, wR ref(F 2) = 0.0829, T = 100 K.

Crystal structure of catena-poly{(μ2-N 1,N 2-bis[(pyridin-4-yl)methyl]ethanediamide-κ2 N:N′)-bis(O,O′-di-isopropyldithiophosphato-κ1 S)zinc(II)} — acetonitrile (1/1), C26H42N4O6P2S4Zn⋅C2H3N

C28H45N5O6P2S4Zn, monoclinic, P21/c (no. 14), a = 7.73670(10) Å, b = 21.56370(10) Å, c = 23.1184(2) Å, β = 99.121(1)°, V = 3808.12(6) Å3, Z = 4, R gt(F) = 0.0210, wR ref(F 2) = 0.0580, T = 100(2) K.

Crystal structure of catena-poly[(μ2-1,2-bis(3-pyridylmethylene)hydrazine-κ2 N:N′)-bis(O,O′-dimethyl dithiophosphato-κ2-S,S′)cadmium(II)], {C16H22CdN4O4P2S4}n

C16H22CdN4O4P2S4, orthorhombic, Pbca (no. 61), a = 12.66410(10) Å, b = 13.00140(10) Å, c = 15.30720(10) Å, V = 2520.35(3) Å3, Z = 4, R gt(F) = 0.0186, wR ref(F 2) = 0.0503, T = 100(2) K.

Crystal structure of catena-poly[(bis(O,O′-diethyl dithiophosphato-κ2 S,S′)-μ2-1,2-bis(3-pyridylmethylene)hydrazine-κ2 N:N′)cadmium(II)], {C20H30CdN4O4P2S4}n

C20H30CdN4O4P2S4, triclinic, P1̄ (no. 2), a = 9.0764(3) Å, b = 9.3969(3) Å, c = 9.6964(3) Å, α = 86.516(3)°, β = 63.362(3)°, γ = 75.250(3)°, V = 713.50(4) Å3, Z = 1, R gt(F) = 0.0166, wR ref(F 2) = 0.0462, T = 100(2) K.

Crystal structure of catena-[(μ2-pyrazine-κ2 N:N′)-bis(O,O′-di-ethyldithiophosphato-κ2 S,S′)cadmium(II)], {C12H24CdN2O4P2S4}n

C12H24CdN2O4P2S4, monoclinic, P2/n (no. 13), a = 11.7844(2) Å, b = 7.6063(1) Å, c = 13.1965(2) Å, β = 111.594(2)°, V = 1099.86(3) Å3, Z = 2, R gt(F) = 0.0171, wR ref(F 2) = 0.0467, T = 100 K.

The remarkable propensity for the formation of C–H⋯π(chelate ring) interactions in the crystals of the first-row transition metal dithiocarbamates and the supramolecular architectures they sustain

C–H⋯π(chelate ring) interactions play an important role in assembling first-row transition metal dithiocarbamates in their crystals.

A redetermination of the crystal structure of catena-poly[(bis(O,O′-isopropyl dithiophosphato-κ2 S,S′)-(μ2-1,2-bis(3-pyridylmethylene)hydrazine-κ2 N,N′)cadmium(II)], {C24H38CdN4O4P2S4}n

C24H38CdN4O4P2S4, monoclinic, P21/n (no. 14), a = 12.2264(1) Å, b = 10.8805(1) Å, c = 12.9590(1) Å, β = 108.172(1)°, V = 1637.95(3) Å3, Z = 2, R gt(F) = 0.0183, wR ref(F 2) = 0.0468, T = 100(2) K.

The pseudosymmetric low temperature polymorph of catena-poly[(μ2-4,4′-bipyridyl-κN,N′)-bis(O,O′-diethyldithiophosphato-κS)-cadmium(II)], {C18H28CdN2O4P2S4}n

C18H28CdN2O4P2S4, triclinic, P1̄ (no. 2), a = 10.3735(1) Å, b = 15.2066(2) Å, c = 26.5231(2) Å, α = 85.178(1)°, β = 81.311(1)°, γ = 71.541(1)°, V = 3920.17(7) Å3, Z = 6, Rgt(F) = 0.0214, wRref(F2) = 0.0556, T = 100(2) K.

Crystal structure of a low-temperature (100 K) polymorph of catena-poly[(μ2-4,4′-bipyridine-κ2N,N′)-bis(O,O′-diethyldithiophosphato-κ1S)zinc(II)], C18H28N2O4P2S4Zn

C18H28N2O4P2S4Zn, triclinic, P1̄ (no. 2), a = 15.2379(1) Å, b = 17.3322(2) Å, c = 21.8829(1) Å, α = 75.919(1)°, β = 78.050(1)°, γ = 68.170(1)°, V = 5159.97(8) Å3, Z = 8, Rgt(F) = 0.0246, wRref(F2) = 0.0681, T = 100 K.

Crystal structure of N-methyl-N-phenyl(methylsulfanyl)carbothioamide, C9H11NS2

C9H11NS2, monoclinic, P21/n (no. 14), a = 5.6183(1) Å, b = 18.2426(3) Å, c = 9.5185(2) Å, β = 96.835(2)°, V = 968.64(3) Å3, Z = 4, Rgt(F) = 0.0303, wRref(F2) = 0.0826, T = 100(2) K.

Crystal structure of catena-{di-aqua-sodium [n-butyl(methyl)carbamothioyl]sulfanide}n, [C6H16NNaO2S2]n

[C6H16NNaO2S2]n, monoclinic, P21/c (no. 14), a = 16.3469(2) Å, b = 5.7512(1) Å, c = 11.8647(1) Å, β = 91.046(1)°, V = 1115.27(3) Å3, Z = 4, Rgt(F) = 0.0212, wRref(F2) = 0.0562, T = 100(2) K.

Crystal structure of 4-phenylpiperazin-1-ium (4-phenylpiperazin-1-yl)carbothioylsulfanide, [C10H15N2][C11H13N2S2]

[C21H28N4S2], monoclinic, P21/c (no. 14), a = 16.1880(2) Å, b = 6.8168(1) Å, c = 19.7605(2) Å, β = 106.412(1)°, V = 2091.73(5) Å3, Z = 4, Rgt(F) = 0.0281, wRref(F2) = 0.0740, T = 100(2) K.

Crystal structure of (4-fluorobenzyl-κC)(bis(2-hydroxyethyl) carbamodithioato-κ2 S,S′)(2,2′-imino-diethanolato-κ3 N,O,O′)tin(IV), C16H25FN2O4S2Sn

C16H25FN2O4S2Sn, monoclinic, P21/n (no. 14), a = 11.2227(1) Å, b = 12.6793(1) Å, c = 13.8731(1) Å, β = 98.282(1)°, V = 1953.50(3) Å3, Z = 4, R gt(F) = 0.0198, wR ref(F 2) = 0.0507, T = 100(2) K.

(N,N-Diiso-propyl-dithio-carbamato)tri-phenyl-tin(IV): crystal structure, Hirshfeld surface analysis and computational study

The crystal and mol-ecular structures of the title triorganotin di-thio-carbamate, [Sn(C6H5)3(C7H14NS2)], are described. The mol-ecular geometry about the metal atom is highly distorted being based on a C3S tetra-hedron as the di-thio-carbamate ligand is asymmetrically chelating to the tin centre. The close approach of the second thione-S atom [Sn⋯S = 2.9264 (4) Å] is largely responsible for the distortion. The mol-ecular packing is almost devoid of directional inter-actions with only weak phenyl-C-H⋯C(phen-yl) inter-actions, leading to centrosymmetric dimeric aggregates, being noted. An analysis of the calculated Hirshfeld surface points to the significance of H⋯H contacts, which contribute 66.6% of all contacts to the surface, with C⋯H/H⋯C [26.8%] and S⋯H/H⋯H [6.6%] contacts making up the balance.

Crystal structure of catena-poly{[μ2-1,2-bis(diphenylphosphino)ethane]dichloridocadmium(II)}, C26H24CdCl2P2

C26H24CdCl2P2, monoclinic, P21/n (no. 14), a = 13.2003(1) Å, b = 11.4655(1) Å, c = 16.7390(1) Å, β = 100.955(1)°, V = 2487.25(3) Å3, Z = 4, R gt(F) = 0.0173, wR ref(F 2) = 0.0451, T = 100(2) K.

Crystal structure of catena-{poly[bis(O,O′-diethyldithiophosphato-S)-(μ2-1,2-bis(4-pyridylmethylene)hydrazine-N,N′)-zinc(II)] di-acetonitrile solvate}, {C20H30N4O4P2S4Zn ⋅ 2 C2H3N}n

C24H36N6O4P2S4Zn, triclinic, P1̄ (no. 2), a = 11.2847(2) Å, b = 12.6967(3) Å, c = 13.6595(3) Å, α = 64.738(2)°, β = 72.181(2)°, γ = 76.681(2)°, V = 1673.68(7) Å3, Z = 2, R gt(F) = 0.0225, wR ref(F 2) = 0.0582, T = 100(2) K.

Crystal structure of tetrakis(O,O′-diisopropyldithiophosphato-κ2 S,S′)-(μ2-1,2-bis(4-pyridylmethylene)hydrazine-κ2 N:N′)zinc(II), C36H66N4O8P4S8Zn2

C36H66N4O8P4S8Zn2, triclinic, P1̄ (no. 2), a = 7.94960(10) Å, b = 11.5638(2) Å, c = 16.5616(2) Å, α = 75.604(1)°, β = 86.321(1)°, γ = 83.103(2)°, V = 1463.06(4) Å3, Z = 1, R gt(F) = 0.0424, wR ref(F 2) = 0.1072, T = 100(2) K.

Crystal structure of catena-poly[(μ2-4,4′-bipyridyl-κN,N′)-bis(O,O′-dimethyldithiophosphato-κS)-zinc(II)], {C14H20N2O4P2S4Zn}n

C14H20N2O4P2S4Zn, triclinic, P1̄ (no. 2), a = 8.0014(2) Å, b = 10.3376(2) Å, c = 14.2488(3) Å, α = 84.676(2)°, β = 76.042(2)°, γ = 79.752(2)°, V = 1124.01(4) Å3, Z = 2, R gt(F) = 0.0265, wR ref(F 2) = 0.0655, T = 100(2) K.

A new structural motif for cadmium dithiocarbamates: crystal structures and Hirshfeld surface analyses of homoleptic zinc and cadmium morpholine dithiocarbamates

The crystal and molecular structures of two homoleptic morpholine-derived dithiocarbamates of zinc, binuclear {Zn[S2CN(CH2CH2)2O)2]2}2 (1), and cadmium, one-dimensional coordination polymer {Cd[S2CN(CH2CH2)2O)2]2}2 (2), are described. In 1, a centrosymmetric binuclear molecule is found as there are equal numbers of chelating and bidentate bridging dithiocarbamate ligands; weak transannular Zn···S interactions are found within the resultant eight-membered {···SCSZn}2 ring which has the form of a chair. The resultant 4+1 S5 donor set is highly distorted with the geometry tending towards a square-pyramid. By contrast, a square-planar geometry is found in centrosymmetric 2 defined by symmetrically chelating dithiocarbamate ligands. The presence of Cd···S secondary bonding in the crystal of 2 leads to a distorted 4+2 S6 octahedron and a linear coordination polymer, which is unprecedented in the structural chemistry of cadmium dithiocarbamates. The analyses of the Hirshfeld surfaces for 1 and 2 show the dominance of H···H, S···H/H···S and O···H/H···O contacts to the surface, i.e. contributing around 90 and 80%, respectively.

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

The crystal chemistry of the zinc-triad binary 1,1-dithiolates, that is, compounds of xanthate [−S2COR], dithiophosphate [−S2P(OR)2], and dithiocarbamate [−S2CNR2] ligands, is reviewed. Owing to a wide range of coordination modes that can be adopted by 1,1-dithiolate anions, such as monodentate, chelating, μ2-bridging, μ3-bridging, etc., there exists a rich diversity in supramolecular assemblies for these compounds, including examples of zero-, one-, and two-dimensional architectures. While there are similarities in structural motifs across the series of 1,1-dithiolate ligands, specific architectures are sometimes found, depending on the metal centre and/or on the 1,1-dithiolate ligand. Further, an influence of steric bulk upon supramolecular aggregation is apparent. Thus, bulky R groups generally preclude the close approach of molecules in order to reduce steric hindrance and therefore, lead to lower dimensional aggregation patterns. The ligating ability of the 1,1-dithiolate ligands also proves crucial in determining the extent of supramolecular aggregation, in particular for dithiocarbamate species where the relatively greater chelating ability of this ligand reduces the Lewis acidity of the zinc-triad element, which thereby reduces its ability to significantly expand its coordination number. Often, the functionalisation of the organic substituents in the 1,1-dithiolate ligands, for example, by incorporating pyridyl groups, can lead to different supramolecular association patterns. Herein, the diverse assemblies of supramolecular architectures are classified and compared. In all, 27 structurally distinct motifs have been identified.