Reactions of the complexes [Re₂(CO)₉(η ¹-P-P)] (P-P = Ph₂P(CH₂)_nPPh ₂, 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 [Re ₂(CO)₉(η¹-P-P)] (P-P=Ph ₂P(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 Me ₃NO 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.