A Series of Compounds Based on [P2W18O62]6- and Transition Metal Mixed Organic Ligand Complexes with High Catalytic Properties for Styrene Epoxidation.

Abstract

Seven compounds based on [P2W18O62]6- ({P2W18}) were successfully prepared and carefully characterized. [HC5H5N][Cu(2,2'-bpy)2]2[HP2W18O62]·2H2O (bpy = bipyridine) (1) is constructed from {P2W18} bridged by [Cu(2,2'-bpy)2]2+. [HC5H5N][Zn(2,2'-bpy)2]2[HP2W18O62]·4H2O (1a) is isostructural and isomorphous with compound 1. [Cu4(2,2'-bpy)3(nic)3(OH)2(H2O)][H3P2W18O62]·0.5H2O (nic = nicotinic acid) (2) is formed by {P2W18} and tetracopper transition metal mixed organic ligand complexes (TMMCs). [Cu2(2,2'-bpy)2(C2O4)]3[P2W18O62]·3H2O (3) is made up of {P2W18} and bicopper TMMCs, [Cu6(2,2'-bpy)6(OH)6][P2W18O62]·2H2O (4) is built up from {P2W18}, and hexacopper complexes of 2,2'-bpy and hydroxyls. [Cu(2,2'-bpy)(hnic)0.5][Cu3(2,2'-bpy)3(hnic)2(H2O)2][H3P2W18O62] (hnic = hydroxyl nicotinic acid) (5a) contains two different TMMCs. In addition, compound 5a is the first example of a compound that contains Cu-π interactions. [Cu2(2,2'-bpy)2(hnic)][H4P2W18O62]· xH2O ( x ≈ 50) (5b) is based on {P2W18} and [Cu2(2,2'-bpy)2(hnic)]2+. We discuss the mechanisms for the formations of these compounds. All the catalytic performances of the compounds for styrene epoxidation to styrene oxide are high.