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)_xM(μ-CN)_yM*(CN)_4−y}_∞ [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)₄Ba(μ-CN)₃Ni(CN)}_∞ 1, {(DMF)₄Sr(μ-CN)₃Ni(CN)}_∞ 4, {(DMF)₄Sr(μ-CN)₃Pd(CN)}_∞ 5, and {(DMF)₄Sr(μ-CN)₃Pt(CN)}_∞ 6 form isostructural one-dimensional “ladder” arrays through isocyanide linkages (M-NC-M*), while {(DMF)₃Ba(μ-CN)₄Pd}_∞ 2, and {(DMF)₃Ba(μ-CN)₄Pt}_∞ 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/SiO₂ and Sr−Pd/SiO₂ 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/SiO₂.