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}8 [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)}8 1, {(DMF)₄Sr(µ- CN)₃Ni(CN)}8 4, {(DMF)₄Sr(µ-CN) ₃Pd(CN)}8 5, and {(DMF)₄Sr(µ-CN) ₃Pt(CN)}8 6 form isostructural one-dimensional "ladder" arrays through isocyanide linkages (M-NC-M*), while {(DMF)₃Ba(µ-CN)₄Pd}8 2, and {(DMF) ₃Ba(µ-CN)₄Pt}8 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/Si0₂ and Sr-Pd/Si0₂ 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/Si0₂. © 2009 American Chemical Society.