Synthesis, Structure and Reactivity of Bis(phosphido)‐Bridged Dinuclear Carbonyls of Platinum(I)

Abstract

AbstractThe platinum(I) dinuclear carbonyl [Pt2(μ‐PtBu2)2(PtBu2H)(CO)] (4) reacts with carbon monoxide (80 atm) to give the dicarbonyl complex [Pt(μ‐PtBu2)(CO)]2 (9), which is thermally and air stable if protected from moisture. Wet solvents convert 9 into the known trinuclear hydride Pt3(μ‐PtBu2)3(CO)2(H) (10), which is also formed by treating 9 with molecular hydrogen (180 atm). The reaction of 4 or 9 with phosphanes [PR3 = PMe3, PPh3, PCy3, PCy2H] results in the formation of the corresponding derivatives [Pt2(μ‐PtBu2)2(PtBu2H)(PR3)] [11, R = Me; 12, R = Ph; 13, R = Cy; 14, R3 = Cy2H], [Pt2(μ‐PtBu2)2(CO)(PR3)] [15, R = Me; 16, R = Ph; 17, R = Cy] or [Pt(μ‐PtBu2)(PR3)]2 [18, R = Me; 19, R = Ph; 20, R = Cy] in good yields. Complex 19 is protonated at platinum by CF3SO3H yielding the hydride [Pt2(μ‐PtBu2)2(H)(PPh3)2]CF3SO3 (21). The protonation of asymmetrically substituted 12 forms rapidly the kinetic hydride [(tBu2HP)Pt(μ‐PtBu2)2Pt(H)(PPh3)]CF3SO3 (22a), which then isomerises slowly to the more stable isomer [(Ph3P)Pt(μ‐PtBu2)2Pt(H)(PtBu2H)]CF3SO3 (22b). Dicarbonyl 9 is instead protonated at the phosphorus atom of a bridging phosphide; the unstable product of this reaction can be intercepted by adding CO to give the monophosphido‐bridged [Pt2(μ‐PtBu2)(PtBu2H)(CO)3]CF3SO3 (24) as a mixture of two isomers. The X‐ray crystal and molecular structures of 9, of a 2:1 mixture of 9 and 10, and of complexes 18, 19 and 21 are also reported.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)