Tetrathiomolybdate Complexes of Rhodium(I) with Molybdenum–Rhodium Interactions

Abstract

The synthesis and characterization of the tetrathiomolybdatorhodium(I) monoanionic complexes [L2Rh(μ-S)2MoS2](-) (L = CO (3), P(OPh)3 (4), P(O-o-Tol)3 (P(o-CH3C6H4)3; 5), P(OMe)3 (6), P(OEt)3 (7), P(O-i-Pr)3 (8); L2 = COD (1,5-cyclooctadiene; 2), cis-dppen (cis-Ph2PCH═CHPPh2; 9), dppe (Ph2PCH2CH2PPh2; 10), dppb (Ph2P(CH2)4PPh2; 11)) is presented. The complex 2 (NEt4(+) salt) was characterized by X-ray diffraction analysis. A detailed DFT study of the electronic structures of 2-4 and 6-8 has revealed the existence of extended electron delocalization over the four-membered Rh(μ-S)2Mo ring and hence the possibility of electronic communication between the metal centers. The electronic spectra were studied with TDDFT calculations, and the main absorption band in the visible region was assigned to ν(Rh→Mo) electron transfer transition, which is actually a HOMO-LUMO transition. The ν(Rh→Mo) transition was found to correlate linearly both with Tolman's electronic parameter of the phosphite ligands and the calculated HOMO-LUMO gap of the complexes, rendering it a well-defined ligand electronic parameter, which describes the net donating ability of monodentate and bidentate ligands (CO, COD, phosphites, diphosphines). The study of the variation of Δδ((31)P) and (1)J(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.

Topological analysis of the metal-metal bond: A tutorial review

“…The number of bonded metal atoms may be also evidenced through the hyperfine structure of the ESR signal of the radical formed upon oxidation of the polynuclear complex [21,26] 5. M-M bonding studies using electronic spectroscopy: in tetrathiomolybdatorhodium(I) monoanionic complexes, the maximum absorption band was found to involve a charge transfer ν(Rh→Mo) electronic transition, the wavelength of which correlates linearly both with Tolman's electronic parameter of the phosphite ligands and the calculated HOMO-LUMO gap of the complexes [27]. The red-shifted photoluminescence observed in biand polynuclear silver complexes was assigned to Ligand to Metal Charge transfer (LMCT) emissions perturbed by the short Ag-Ag contacts (LMMCT electronic transitions) [16].…”

Classification of the Electronic Properties of Chelating Ligands in cis-[LL′Rh(CO)2] Complexes

“…A detailed analysis of the three components of the shielding tensor was indeed required to elucidate the unexpected low downfield 13 C NMR chemical shifts of such carbenoid species, featuring a carbon atom with a nucleophilic character . Experimental scales relying on UV–visible measurements of chromium carbonyl- or tetrathiomolybdate rhodium complexes have been also reported. However, the most widely employed strategy is related to the Tolman’s electronic parameter (TEP), based on the infrared (IR) stretching frequency of carbon monoxide of A 1 symmetry ( v IR A1 (CO)), in Ni­(CO) 3 L complexes .…”

Structural and Electronic Investigation of Tetrachalcogenidomolybdate Dianions

“…X‐ray crystal structures are known for a wide variety of compounds containing [MoS 4 ],, and [MoO 2 S 2 ] dianions. Despite the utility of (PPh 4 ) 2 [MoS 4 ] in the preparation of bimetallic compounds, and nucleophilic substitution reactions with alkyl halides, its molecular structure has not yet been reported.…”