Reactions of the complexes [Re 2(CO) 9(η 1-P–P)] (P–P=Ph 2P(CH 2) nPPh 2, n=1–6) with Me 3NO: formation of close-bridged complexes [Re 2(CO) 8(μ-P–P)] and phosphine oxide complexes [Re 2(CO) 9{P–P(O)}

Abstract

Reactions of [Re 2(CO) 10] with Me 3NO and diphosphines [Ph 2P(CH 2) n PPh 2, n=1–6] yield mixtures of the monodentate–coordinated diphosphine complexes [Re 2(CO) 9(η 1-P–P)] (P–P=Ph 2P(CH 2) n PPh 2, n=1–6) (yields 5–40%) and bridged dimers [{Re 2(CO) 9} 2(μ-P–P)] (5–50%). These complexes were isolated as either equatorial or axial isomers, or a mixture of two isomers. Reactions of the monodentate complexes with Me 3NO yield close-bridged complexes [Re 2(CO) 8(μ-P–P)] and phosphine oxide complexes [Re 2(CO) 9{P–P(O)}]. The structures of the close-bridged complexes 1 ( n=3) and 2 ( n=4), were determined by X-ray crystallography. The Re–Re bond in the close-bridged complex with the longest phosphine chain ( n=6) is readily cleaved in CDCl 3 to give the complex [{ cis-ReCl(CO) 4} 2(μ-dpph)] ( 3) as the product, the structure of which was also determined by X-ray crystallography.