A series of new fluororhodium(I) complexes †

Abstract

The reaction of [Rh{η2-O2S(O)CF3}(PPri3)2] 1 with terminal alkynes RCCH (R = Ph or But) led to the formation of the vinylidene compounds trans-[Rh{η1-OS(O)2CF3}(CCHR)(PPri3)2] 2a,2b, which on treatment with tetrabutylammonium fluoride hydrate or KF gave the fluororhodium(I) complexes trans-[RhF(CCHR)(PPri3)2] 3a,3b in ca. 70% yield. An alternative route for the preparation of 3a (R = Ph) is based on the reaction of phenylacetylene with the dimer [{Rh(µ-F)(PPri3)2}2] 4, the latter being obtained from 1 and [NBu4]F hydrate as starting materials. Compound 4 reacts smoothly with L′ = CO, CNC6H3Me2-2,6, C2Ph2 and C2H4 to afford the mononuclear complexes trans-[RhF(L′)(PPri3)2], of which that with L′ = C2H4 was characterized by X-ray crystallography. In contrast to the hydroxo compound trans-[Rh(OH)(CCHPh)(PPri3)2], which on treatment with acids HX (X = CF3SO3, CH3CO2, PhO or PhCC) gave trans-[RhX(CCHPh)(PPri3)2], the fluoro derivative 3a reacts only with CF3SO3H and PhCCH by ligand substitution to yield the corresponding compounds. Acetic acid and phenol interact with 3a via XH· · ·FRh hydrogen bridges to form 1∶1 adducts, of which that with X = CH3CO2 rearranges to give trans-[Rh(O2CMe)(CCHPh)(PPri3)2] and probably trans-[Rh(FHF)(CCHPh)(PPri3)2].