Synthesis, structure and spectral properties of dithiocarbamato bridged dirhenium(III,II) complexes: A combined experimental and theoretical study

Abstract

Sodium salts of dimethyldithiocarbamate, diethyldithiocarbamate and pyrrolidinedithiocarbamate react with the multiply bonded paramagnetic dirhenium(III,II) complex Re2(μ-O2CCH3)Cl4(μ-dppm)2, 1 (dppm=Ph2PCH2PPh2) in refluxing ethanol to afford the paramagnetic substitution products of the type Re2(η2-S,S)2(μ-S,S)(μ-Cl)2(μ-dppm), where S,S represents the dithiocarbamato ligands [S,S=S2CNMe2, 4(LMe); S2CNEt2, 4(LEt) and S2CN(CH2)4, 4(LPyr)]. These are the first examples of dirhenium complexes that contain bridging dithiocarbamato ligand along with the dppm ligand. These complexes have very similar spectral (UV–Vis, IR, EPR) and electrochemical properties which are also reported. The identity of 4(LEt) has been established by single-crystal X-ray structure determination (Re–Re distance 2.6385 (9)Å) and is shown to have edge-shared bioctahedral structure. The electronic structure and the absorption spectra of the complexes are scrutinized by the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) analyses.