Neutral PtRh2and PtRh4Tetraalkynyl Complexes. X-ray Crystal Structures of {Pt(C⋮CBut)4[Rh2(μ-X)(COD)2]2} (X = Cl, OH)

The reaction of 2 equiv of [Rh(COD)(acetone) 2 ] + with the dianionic homoleptic species [Pt(C⋮CR) 4 ] 2 - (R = Bu t ( 1a ), SiMe 3 ( 1b )) in acetone (molar ratio 2:1) gives the expected neutral trinuclear adducts {Pt(μ-C⋮CR) 4 [Rh(COD)] 2 } (R = Bu t ( 2a ), SiMe 3 ( 2b )) in moderately good yield. Further reaction of 2a with the binuclear [Rh(μ-X)(COD)] 2 (X = Cl, OH) derivatives (molar ratio 1:1) produces the formation of unusual pentanuclear {Pt(μ-C⋮CBu t ) 4 [Rh 2 (μ-X)(COD) 2 ] 2 } complexes (X = Cl ( 3a ), OH ( 4a )), which are formed by a dianionic “Pt(C⋮CBu t ) 4 ” fragment and two dinuclear cationic “Rh 2 (COD) 2 (μ-X)” units connected through bridging alkynyl ligands. The molecular structures of complexes 3a and 4a have been established by X-ray crystallography.