Syntheses and Structures of Alkaline Earth−Transition Metal Bimetallic Complexes As Heterogeneous Hydrodechlorination Catalyst Precursors

A series of alkaline earth-transition metal heterobimetallic complexes {(DMF)(x)M(mu-CN)(y)M*(CN)(4-y)}(infinity) [M = Ba: M* = Ni 1, M* = Pd 2, M* = Pt 3; M = Sr: M* = Ni 4, M* = Pd 5, M* = Pt 6; x = 3 or 4; y = 3 or 4] was prepared. Single-crystal X-ray diffraction analysis revealed that {(DMF)(4)Ba(mu-CN)(3)Ni(CN)}(infinity) 1, {(DMF)(4)Sr(mu-CN)(3)Ni(CN)}(infinity) 4, {(DMF)(4)Sr(mu-CN)(3)Pd(CN)}(infinity) 5, and {(DMF)(4)Sr(mu-CN)(3)Pt(CN)}(infinity) 6 form isostructural one-dimensional "ladder" arrays through isocyanide linkages (M-NC-M*), while {(DMF)(3)Ba(mu-CN)(4)Pd}(infinity) 2, and {(DMF)(3)Ba(mu-CN)(4)Pt}(infinity) 3 are two-dimensional puckered sheet like arrays. These bimetallic complexes can serve as effective precursors for the synthesis of supported bimetallic catalysts. It has been established that Ba-Pd/SiO(2) and Sr-Pd/SiO(2) catalysts, prepared from 2 and 5 loaded onto a silica support, delivered specific reaction rates in the hydrodechlorination of mono- and dichloro benzene that were over an order of magnitude greater than that achieved with conventional Pd/SiO(2).