Dimensional Structures and Electrocatalytic Activities of Platinum(II)-Palladium(II)-Manganese(II) Coordination Polymers Controlled by Chloride versus Bromide.

Here we report the synthesis and structural characterization of heterotrimetallic (PtII2PdII2MnII2)n coordination polymers that show different dimensionalities and electrocatalytic activities depending on chloride and bromide employed in the system. The reaction of the PtII2PdII2 tetranuclear complex [Pd2Pt2(NH3)4(d-pen)4] (1), bearing free carboxylate groups, with Mn2+ in the presence of chloride produced the (PtII2PdII2MnII2)n coordination polymer [Mn2Cl2(H2O)6(1)]Cl2 (2Cl), in which the PtII2PdII2 units of 1 are linked by [MnCl(H2O)3]+ moieties in a 1:2 ratio to form a 2D sheetlike structure. The corresponding reaction in the presence of bromide also gave the (PtII2PdII2MnII2)n coordination polymer [Mn2(H2O)6(1)]Br4 (3Br), but 3Br adopted a 3D network structure via a 1:1 linkage of the PtII2PdII2 units with [Mn2(H2O)6]4+ moieties. These complexes showed appreciably different electrocatalytic activities for H2 evolution.