PROTON LABILITY IN HIGHLY HINDERED DINUCLEAR PALLADIUM(I) MU-PHOSPHIDO-SECONDARY PHOSPHINE COMPLEXES - CRYSTAL-STRUCTURES OF [PD-2(MU-PBU(2)(T))(PCY(2)H)(3)(CO)]BF4 AND [PD-2(MU-PBU(2)(T)) (PCY(2)H)(2)(MU,ETA(2),ETA(2)-ISOPRENE)]BF4

The reactions of the dinuclear cationic complexes [Pd-2(mu-PBu(2)(t))( PR(3))(4)](+) (PR(3) = PCy(2)H, PMe(3)) with CO or isoprene proceed wi th substitution of one or two phosphine ligands giving the correspondi ng [Pd-2(mu-PBu(2)(t))(PR(3))(3)(CO)](+) and [Pd-2(mu-PBu(2)(t)) (mu,e ta(2),eta(2)-isoprene)(PR(3))(2)](+) cations. [Pa-2(mu-PBu(2)(t))(PCy( 2)H)(3)(CO)](+) equilibrates in solution to a mixture of monocarbonyl derivatives arising from bridging phosphido/terminal phosphine interch ange. The complexes were characterized by multinuclear 1-D and 2-D NMR spectroscopy. The crystal and molecular structures of [Pd-2(mu-PBu(2) (t))(PCy(2)H)(3)(CO)]BF4 and (t))(PCy(2)H)(2)(mu,eta(2),eta(2)-isopren e)]CF3SO3 were solved by single-crystal X-ray diffraction studies.