Heterotrimetallic tetrathiomolybdate and tetrathiotungstate complexes of rhodium(I) and copper(I) with Rh-Mo(W)-Cu interactions

Abstract

The synthesis and characterization of the monoanionic heterotrimetallic (d8···d0···d10) complexes [L2Rh(μ-S)2M(μ-S)2CuCl]− (L = P(OPh)3, P(O-o-Tol)3 (P(O-o-CH3C6H4)3), P(OMe)3, P(OEt)3, P(OiPr)3; L2 = COD (1,5-cyclooctadiene), cis-dppen (cis-Ph2PCH = CHPPh2); M = Mo, W) is presented. The complex (NEt4)[(cis-dppen)Rh(μ-S)2W(μ-S)2CuCl] was characterized by X-ray diffraction analysis. The detailed DFT study of the electronic structure of the complexes with P(OMe)3 and COD ligands has revealed the existence of extended electron delocalization over the atom-sharing (spiro) four-membered rings system Rh(μ-S)2M(μ-S)2Cu and the possibility of electronic communication between the terminal metal centers. The electronic spectra of the complexes with P(OMe)3 ligands were studied with TDDFT calculations and the main absorption band in the visible region was assigned to ν(Rh → Mo/W) electron transfer transition. The ν(Rh → Mo/W) transition was found to correlate linearly with Tolman’s electronic parameter of the phosphite ligands, making it an electronic parameter for the ligands studied. Finally, the study of the dependence of Δδ(31P) and 1J(Rh-P) of the phosphite complexes, with respect to the QALE model electronic parameters χd, πp and Ear, has succeeded in the assessment of the σ and π effects on these NMR spectral parameters.