Hybrid Cu-Containing Compounds Based on Lacunary Strandberg Anions: Synthesis under Mild Conditions, Crystal Structure, and Magnetic Properties.

A one-pot reaction of a copper source (metallic powder Cu or Cu salts) and bpy (bpy = 2,2'-bipyridine) in the presence of (NH)HPO and (NH)MoO·4HO yields heterometallic hybrid compounds of the general type {[Cu(bpy)(HO)][PMoO]}. The structures exhibit a number of phosphomolybdate POMs including not only a common Strandberg anion [PMoO] but also its unprecedented bi- and trilacunary derivatives [PMoO] and [PMoO]. The structural determinants including the metal source (copper powder copper salts), counterion of the salts, and stoichiometry of the reagents were examined. An EPR study revealed the formation of different Cu complexes in the reaction mixture depending on the copper precursor. The obtained compounds have been found to possess selectivity toward the sorption of methylene blue in a mixture of organic dyes. DC magnetic measurements of - indicate rather strong antiferromagnetic metal-metal exchange interactions. Compound exhibits field-induced slow magnetic relaxation in AC magnetic measurements, which is a rarely observed phenomenon among Cu(II) complexes.