Hybrid Cu-Containing Compounds Based on Lacunary StrandbergAnions: Synthesis under Mild Conditions, Crystal Structure, andMagnetic Properties

A one-pot reaction of a copper source (metallicpowder Cu0or Cu2+salts) and bpy (bpy = 2,2 '-bipyridine) in thepresence of (NH4)2HPO4and (NH4)6Mo7O24middot4H2Oyieldsheterometallic hybrid compounds of the general type {[Cu-(bpy)n(H2O)m]p[P2MoxOy]}. The structures exhibit a number ofphosphomolybdate POMs including not only a commonStrandberg anion [P2Mo5O23]6-but also its unprecedented bi-and trilacunary derivatives [P2Mo3O18]8-and [P2Mo2O15]8-. Thestructural determinants including the metal source (copper powdervscopper salts), counterion of the salts, and stoichiometry of thereagents were examined. Anex situEPR study revealed theformation of different CuIIcomplexes in the reaction mixturedepending on the copper precursor. The obtained compoundshave been found to possess selectivity toward the sorption of methylene blue in a mixture of organic dyes. DC magneticmeasurements of1-3indicate rather strong antiferromagnetic metal-metal exchange interactions. Compound1exhibitsfield-induced slow magnetic relaxation in AC magnetic measurements, which is a rarely observed phenomenon among Cu(II) complexes.