Synthesis and Characterization of Single-Source Molecular Precursors to BinaryMetal Sulphides: Bis(Diethyldithiocarbamato) M(II)Trialkylphosphine (M=Zn and Cd) Adducts

摘要

Monomeric, five-coordinate bis(diethyldithiocarbamato)M(II)(trialkylphosphine)complexes, 1 (M=Zn, alkyl=Me), 2 (M=Zn, alkyl=Et), 3 (M=Cd, alkyl=Me), and 4 (M=Cd, alkyl=Et) have been synthesized by addition of trialkylphosphine ligands to toluene solutions of bis(diethyldithiocarbamato)M(II) (M=Zn, and Cd). The bidentate ligand, 1,2-bis(diethylphosphino)ethane (DEPE) reacted with bis(diethyldithiocarbamato)M(II) (M=Zn, Cd) and a 1:1 mixture of (Et2NCS2)2Zn2:(Et2NCS2)2Cd2 in toluene to form five-coordinate, dinuclear DEPE-bridged complexes, (Et2NCS2)2M2(mu-DEPE), 5 (M=Zn), 6 (M=Cd) and 7 (Et2NCS2)2Zn)(muEt2PCH2CH2PEt2)Cd(Et2NCS2)2), respectively. The composition and structure of all compounds was confirmed by elemental analyses, infra-red spectroscopy, 1H, 13C (1H) and 31P(1H) nuclear magnetic resonance (NMR) and in selected cases by X-ray crystallography. The solid-state structures of (Et2NCS2)2ZnPMe3(1) and (Et2NCS2)2CdPEt3(4) have been determined by single-crystal X-ray diffraction. Thermogravimetric analysis (TGA) of compounds 1-3 showed that the PR3 ligands dissociated prior to thermal decomposition. However, compound 4 exhibited a single weight loss to give crystalline CdS as determined by X-ray powder diffraction, electron diffraction and transmission electron microscopy. The homobimetallic species, 5 and 6 also decomposed to give ZnS and CdS, respectively while the heterobimetallic species, 7, thermally decomposed to give crystalline Zn0.5S according to X-ray powder diffraction data.