Thermostructural Behavior in a Series of Lanthanide-Containing Polyoxotungstate Hybrids with Copper(II) Complexes of the Tetraazamacrocycle Cyclam: A Single-Crystal-to-Single-Crystal Transformation Study

A series of 14 isostructural [Cu(cyclam)]2[{Cu(cyclam)}4{(α-GeW11O39)Ln(H2O)(OAc)}2]·18H2O (1-Ln, where Ln = La–Lu; cyclam = 1,4,8,11-tetraazacyclotetradecane) polyoxometalate-based hybrids reported herein represent (i) the first example of a two-dimensional covalent hybrid lattice involving the [{(α-XW11O39)Ln(H2O)(OAc)}2]n− archetype and (ii) the first structural characterization of such a dimeric polyoxotungste for Ln = La and Pr as well as for the combination of X = Ge and Ln = Ce, Nd, Sm, or Lu. Compounds 1-Ln have been characterized by elemental analyses, infrared spectroscopy, and thermogravimetric analysis, and their thermostructural behavior has been monitored by powder and single-crystal X-ray diffraction. The title compounds undergo two single-crystal-to-single-crystal transformations triggered by thermal dehydration leading to the [{Cu(cyclam)}6{(α-GeW11O39)Ln(H2O)(OAc)}2]·4H2O intermediate (2-Ln, where Ln = Eu or Er) and [Cu(cyclam)]0.5[{Cu(cyclam)}5.5{(α-GeW11O39)Ln(OAc)}2] (3-Ln, where Ln =...