Reactions of the complexes [Re2(CO)9(η1-P–P)] (P–P=Ph2P(CH2)nPPh2, n=1–6) with Me3NO: formation of close-bridged complexes [Re2(CO)8(μ-P–P)] and phosphine oxide complexes [Re2(CO)9{P–P(O)}]

Reactions of [Re2(CO)10] with Me3NO and diphosphines [Ph2P(CH2)nPPh2, n=1–6] yield mixtures of the monodentate–coordinated diphosphine complexes [Re2(CO)9(η1-P–P)] (P–P=Ph2P(CH2)nPPh2, n=1–6) (yields 5–40%) and bridged dimers [{Re2(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 Me3NO yield close-bridged complexes [Re2(CO)8(μ-P–P)] and phosphine oxide complexes [Re2(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 CDCl3 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.