Bis(hydrosulfido)-bridged dinuclear rhodium(i) complexes as a platform for the synthesis of trinuclear sulfido aggregates with the core [MRh2(μ3-S2)] (M = Rh, Ir, Pd, Pt, Ru)

Abstract

The reaction of [Rh(μ-SH)(CO)(PPh₃)]₂ or [Rh(μ-SH){P(OPh)₃}₂]₂ with [Cp*MCl₂]₂ (M = Rh, Ir) in the presence of NEt₃ afforded the Rh₃ and IrRh₂ sulfido-bridged compounds [Cp*M(μ₃-S)₂Rh₂(CO)₂(PPh₃)₂] (M = Rh, 1; Ir, 2) and [Cp*Rh(μ₃-S)₂Rh₂{P(OPh)₃}₄] (3). The reaction with [MCl₂(cod)] (M = Pd, Pt), cis-[PtCl₂(PPh₃)₂] or [(η⁶-C₆H₆)RuCl₂]₂ under the same experimental conditions gave [(cod)M(μ₃-S)₂Rh₂{P(OPh)₃}₄] (M = Pd, 6; Pt, 7), [(cod)M(μ₃-S)₂Rh₂(CO)₂(PPh₃)₂] (M = Pd, 8; Pt, 9), [(PPh₃)₂Pt(μ₃-S)₂Rh₂(CO)₂(PPh₃)₂] (10) and [(η⁶-C₆H₆)Ru(μ₃-S)₂Rh₂(CO)₂(PPh₃)₂] (12), with PdRh₂, PtRh₂ and RuRh₂ trimetallic cores. The aggregates derived from [Rh(μ-SH)(CO)(PPh₃)]₂ were isolated as a mixture of trans and cis isomers in which the trans isomer predominates. The reaction of [Rh(μ-SH){P(OPh)₃}₂]₂ with 2 equiv. of n-BuLi at 253 K followed by addition of [Cp*IrCl₂]₂ gave [Cp*Ir(μ₃-S)₂Rh₂{P(OPh)₃}₄] (4) and [Cp*₂ClIr₂(μ₃-S)₂Rh{P(OPh)₃}₂] (5) in a 3 : 2 ratio. The RuRh₂ compound [(η⁶-C₆H₆)Ru(μ₃-S)₂Rh₂{P(OPh)₃}₄] (11) was prepared similarly from [Rh(μ-SH){P(OPh)₃}₂]₂ and [(η⁶-C₆H₆)RuCl₂]₂ using n-BuLi as a deprotonating agent. The molecular structures of compounds 3, 6, 7, 9 and 11 have been determined by X-ray analysis. The trinuclear complexes exhibit an asymmetric triangular metal core with two triply bridging sulfido ligands resulting in a distorted trigonal-bipyramidal M₃(μ₃-S)₂ heterometallic metal–sulfur core.