Structural diversity in the mercury(II) bis( N , N -dialkyldithiocarbamate) compounds: an example of the importance of considering crystal structure when rationalising molecular structure

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.

Bis[bis(N-2-hydroxyethyl,N-isopropyl-dithiocarbamato)mercury(II)]2: crystal structure and Hirshfeld surface analysis

The presence of both κ2-chelating and μ2,κ2-tridentate bridging dithiocarbamate ligands in centrosymmetric {Hg[S2CN(iPr)CH2CH2OH]2}2 (1) leads to globular aggregates that are linked into a three-dimensional architecture via hydroxyl-O–H···O(hydroxy) hydrogen bonding. The structure contrasts that of Hg[S2CN(CH2CH2OH)2]2 (2; this is a literature structure) in which square planar units are connected into supramolecular chains via Hg···S secondary bonding; chains are connected in the crystal structure by hydroxyl-O–H···O(hydroxy) hydrogen bonding. A Hirshfeld surface analysis on 1 and 2 reveal the influence of O–H···O and Hg···S interactions on the molecular packing as well as the distinctive interactions, such as C–H···S interactions in 1 and C–H···π (HgS2C) contacts in 2. A bibliographic survey shows the different structural motifs observed for 1 and 2 are complimented by an additional five motifs for binary mercury(II) dithiocarbamates revealing a fascinating structural diversity for this class of compound.

Effect of co-crystallization of ethanol, pyridine and 2,2′-bipyridine on molecular aggregation in bis(1,2,3,4-tetrahydroquinolinedithiocarbamato-S,S′)mercury(ii) and synthesis of HgS nanoparticles

Different structural motifs are obtained by co-crystallization of 2,2′-bipyridine, ethanol and pyridine with [Hg(thqdtc)₂].

Synthesis, characterization and thermal studies of Zn(II), Cd(II) and Hg(II) complexes of N-methyl-N-phenyl dithiocarbamate: the single crystal structure of [(C(6)H(5))(CH(3))NCS(2)](4)Hg(2)

Zn(II), Cd(II) and Hg(II) complexes of N-methyl-N-phenyl dithiocarbamate have been synthesized and characterized by elemental analysis and spectral studies (IR, ¹H and ¹³C-NMR). The single crystal X-ray structure of the mercury complex revealed that the complex contains a Hg centre with a distorted tetrahedral coordination sphere in which the dinuclear Hg complex resides on a crystallographic inversion centre and each Hg atom is coordinated to four S atoms from the dithiocarbamate moiety. One dithiocarbamate ligand acts as chelating ligand while the other acts as chelating bridging ligand between two Hg atoms, resulting in a dinuclear eight-member ring. The course of the thermal degradation of the complexes has been investigated using thermogravimetric and differential thermal analyses techniques. Thermogravimetric analysis of the complexes show a single weight loss to give MS (M = Zn, Cd, Hg) indicating that they might be useful as single source precursors for the synthesis of MS nanoparticles and thin films.

Crystal structure, phase transitions, anomalous thermal and elastic properties of bis (butylammonium) zirconium bis(nitrilotriacetate) dihydrate and bis(butylammonium) hafnium bis(nitrilotriacetate) dihydrate, [NH3(CH2)3CH3]2X[N(CH2COO)3]2 · 2 H2O, (X=Zr, Hf)

The isotypic compounds [NH3(CH2)3CH3]2 · X[N(CH2COO)3]2 · 2 H2O, C20H40N4O14X (X: Zr; Hf) crystallize in space group P212121 with lattice constants a 1 = 10.314(4) Å, a 2 = 13.018(6)Å, a 3 = 21.357(8) Å, (Zr-salt) and a 1 = 10.308(4) Å, a 2 = 12.996(6) Å, a 3 = 21.377(8) Å (Hf-salt), Z = 4. The structure is built up from layers of X[N(CH2COO)3]2 anions with intralayer and interlayer Coulomb interactions to the NH3 groups of the butylammonium cations. In addition, hydrogen bonds of NH3 groups and water molecules with oxygen atoms of the nitrilotriacetate groups are present.

Strong anomalies occur in thermal expansion and elastic properties between 340 K and 160 K in both species, e.g. the thermoelastic constants T 11, T 33, T 44, T 12, T 13 and T 23 attain increasing positive values upon lowering the temperature. The result is a negative temperature derivative of the bulk compressibility over a wide temperature range, a quite unique phenomenon. The piezoelastic constants P 11, P 44 and P 13 show anomalies too. Ultrasonic waves are affected by an increasing attenuation below 250 K which culminates at about 188 K (Zr-salt) and 193 K (Hf-salt), indicating a weakly first-order transition, which is also recognized in differential scanning calorimetry and thermal expansion. The observed anomalies and the transition passing from room temperature to lower temperatures appear to be related mainly to distinct temperature-induced changes in bonding and position of one of the two non-equivalent butylammonium groups and the two water molecules.

Crystal structures of 2,2′-bipyridine adducts of two cadmium O-alkyl dithiocarbonates: rationalisation of disparate coordination geometries based on different crystal packing environments

Two distinct coordination geometries are found in the structures of Cd(S2COR)2(2,2′-bipyridine). For R = CH2CH2OCH3 (1) a N2S2 donor set defines a distorted tetrahedral geometry for cadmium as the xanthate ligands adopt a monodentate coordination mode. By contrast, a N2S3 donor set is found in the structure where R is butyl (2) as one of the xanthate ligands is chelating. An analysis of the crystal structures shows that both lattices feature extensive C–H...π interactions and that in (1) there are C–H...O interactions that are not present in (2). In (2) there are π...π interactions that are absent in (1). A qualitative argument based on crystal packing considerations is proposed to explain the differences in molecular structures.

Triphenylphosphine adducts of silver di-iso-propyl dithiophosphate

The molecular structure of dimeric {[S2P(OiPr)2](PPh3)}2· 2 CHCl3is built up about a centrosymmetric eight-membered ring that adopts a chair conformation as a result of bidentate bridging dithiophos phate ligands. The silver atom is in a trigonal planar geometry. Relatively close transannular Ag…S interactions are noted which, if considered significant, leads to a tridentate dithiophosphate ligand and a distorted tetrahedral geometry for silver. The presence of two PPh3molecules in the coordination sphere of silver in monomeric Ag[S2P(OiPr)2](PPh3)2· 3 CHCl3as well as a bidentate di thiophosphate ligand gives rise to a tetrahedral geometry. Adducts with lower or greater numbers of PPh3ligands could not be obtained pointing to the inherent stability of the characterised structures.

Prevalance of intermolecular Bi … S interactions in bismuth dithiocarbamate compounds: Bi(S2CNR2)3

A series of crystal structures of tris(N,N-di-isobutyldithiocarbamato)bismuth(III), Bi{S2CN(iBu2)}3 (1), tris(N,N-tetramethylenedithiocarbamato)bismuth(III), Bi{S2CN(CH2)4}3 (2), tris(N,N-hexamethylenedithiocarbamato)bismuth(III) chloroform solvate, Bi(S2CN(CH2)6)3 · CHCl3 (3), and tris(N-methyl, N-phenyldithiocarbamato)-bismuth(III) hemi acetonitrile solvate, Bi(S2CN · (Me)Ph)3 · 0.5 CH3CN (4) has been determined and each structure shows the presence of three chelating dithiocarbamate ligands as well as two (in (1) and (2)) or one (in (3) and (4)) intermolecular Bi … S interactions leading to the formation spherical dimeric aggregates. The conclusion of this structural study is that regardless of the size of the dithiocarbamate-bound R groups, intermolecular Bi … S interactions dominate the crystal packing in Bi(S2CNR2)3.

Polymeric topologies in cadmium(II) dithiophosphate adducts of the isomeric n-pyridinealdazines, n = 2, 3 and 4

A series of crystal structures of adducts formed between cadmium dithiophosphate, Cd(S2P(OiPr)2)2, and the isomeric n-pyridinealdazine ligands, n = 2, 3, and 4, are described. A centrosymmetric dimer is found in the 2 : 1 adduct with the 2-isomer, i.e. [Cd(S2P(OiPr)2)2(2-NC5H4C(H) = C(H)C5H4N-2)0.5]2, in which the cadmium atom exists within a cis-N2S4 donor set and the di-pyridyl-type ligand is tetradentate. By contrast, trans-N2S4 donor sets for cadmium and regular bridging modes of coordination lead to polymers with a step-ladder topology are found in the 1:1 adducts with the 3- and 4-isomeric ligands, i.e. [Cd(S2P(OiPr)2)2(n-NC5H4C(H) = C(H)C5H4N-n)]∞, for n = 3 and 4. Differences in aggregation behaviour are related to the binding requirements of the n-pyridinealdazine ligands.

Heterodi- [MAg, MAu (M = Pd, Pt)], Tri- [PdAg(2), PtAg(2), PtAu(2), Pt(2)M (M = Ni, Pt, Cd, Hg)], and Tetranuclear (Pt(2)Ag(2), Pt(2)Au(2)) 1,1-ethylenedithiolato complexes

The reactions of [M(PPh(3))(2)[S(2)C=C[C(O)Me](2)]] [M = Pd (1a), Pt (1b)] with AgClO(4) and PPh(3) or with [Au(PPh(3))(OCMe(2))]ClO(4) afford heterodinuclear [[M(PPh(3))(2)][M'(PPh(3))][S(2)C=C[C(O)Me](2)]]ClO(4) [M = Pd, M' = Ag (2a), M = Pt, M' = Ag (2b), Au (4)] or trinuclear [[M(PPh(3))(2)][M'(PPh(3))](2)[S(2)C=C[C(O)Me](2)]](ClO(4))(2) [M = Pd, M' = Ag (3a), M = Pt, M' = Ag (3b), Au (5)] 1,1-ethylenedithiolato complexes, depending on the molar ratio of the reagents. We have recently reported that, in the absence of added PPh(3), the reactions of [Pt[S(2)C=C[C(O)Me](2)]L(2)] [L = PPh(3) (1b), L(2) = 1,5-cyclooctadiene (cod) (1c)] with AgClO(4) produce the heterotetranuclear derivatives [[PtL(2)](2)Ag(2)[S(2)C=C[C(O)Me](2)](2)]](ClO(4))(2) [L = PPh(3) (6a), L(2) = cod (6b)], which have been used now as efficient transmetallating agents toward gold, platinum, mercury, nickel, copper, or cadmium metal centers to give new types of 1,1-ethylenedithiolato complexes: [[Pt(PPh(3))(2)](2)Au(2)[S(2)C=C[C(O)Me](2)](2)](ClO(4))(2) (7), [(PtL(2))(2)M[S(2)C=C[C(O)Me](2)](2)](ClO(4))(2) [L(2) = cod, M = Pt (8), L = PPh(3), M = Hg (9)], [[Pt(PPh(3))(2)](2)[S(2)C=C[C(Me)=O](2)](2)Ni](ClO(4))(2) (10), and [[Pt(PPh(3))(2)](2)[S(2)C=C[C(Me)=O](2)](2)[M(OClO(3))(2)]] [M = Cu (11), [C(O)Me](2)] moieties but, whereas in 7 they bridge two gold(I) centers through the sulfur atoms, in 11 they chelate the copper(II) center through the oxygen atoms. The last one is the first example of such a coordination mode for the 2,2-diacetyl-1,1-ethylenedithiolato ligand.