Dinuclear Phosphido-Bridged Derivatives of Platinum(I). Synthesis and Characterization of [Pt₂(μ-PBut₂)₂(PBut₂H)(L)] [L = PBut₂R (R = H, Li, n-Heptyl), CO, η²-CS₂]

Contrarily to its palladium analogue, the platinum(II) dihydride [Pt(μ-PBu t 2 )(H)(PBu t 2 H)] 2 ( 3 ) does not reductively eliminate molecular hydrogen to the corresponding Pt(I) dinuclear derivative. The transformation can, however, be achieved in a two-step procedure, i.e., by oxidant-induced hydride abstraction from 3, which produces the cationic monohydride [Pt 2 (μ-PBu t 2 ) 2 (H)(PBu t 2 H) 2 ]PF 6, ( 4 )PF 6, and deprotonation of the latter with a strong base, which produces the desired [Pt(μ-PBu t 2 )(PBu t 2 H)] 2 ( 5 ). Complex 5 can be used as the precursor of other neutral bis-phosphido bridged platinum(I) derivatives. For example, carbon monoxide substitutes in mild conditions one of the terminally bonded secondary phosphines and yields quantitatively the monocarbonyl [Pt 2 (μ-PBu t 2 ) 2 (PBu t 2 H)(CO)], ( 6 ), whose crystal and molecular structure was determined by X-ray diffraction. Crystal data: monoclinic, space group P 2 1 / n (No. 14), Z = 4, a = 9.0910(12) Å, b = 30.527(4) Å, c = 11.903(2) Å, β = 93.78(2)°, R( F o ) = 0.0378, Rw( F o 2 ) = 0.0826 [ I > 2σ( I )]. Complex 6 reacts cleanly with carbon disulfide to give the product of CO substitution [Pt 2 (μ-PBu t 2 ) 2 (PBu t 2 H)(η 2 -CS 2 )] ( 9 ). Further modifications of complex 5 can be achieved by deprotonating with n -BuLi/TMEN one of its secondary phosphines, which produces the lithiated derivative [Pt 2 (μ-PBu t 2 ) 2 (PBu t 2 H)(PBu t 2 Li)] ( 10 ). The latter has been alkylated with 1 - bromoheptane to the soluble derivative [Pt 2 (μ-PBu t 2 ) 2 (PBu t 2 H)(PBu t 2 R)] ( 12 ) (R = n -heptyl).