Polyoxometalate cluster [V12B18O60H6] functionalized with the copper(II) bis-ethylenediamine complex

Abstract

Three compounds based on the polyoxometalate building block [V12B18O60H6], (Na)10[(H2O)V12- B18O60H6] 18H2O (1), Na8[Cu(en)2]2[V12B18O60H6](NO3)2 14.7H2O (2), Na7[Cu(en)2]2[V12B18O60H6] (NO3) 15.5H2O (3), (en = ethylenediamine), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis and TGA. Compound 1 consists of polyoxovanadium borate [V12B18O60H6] clusters which are surrounded by sodium countercations in octahedral sites, stabilized by electrostatic interactions with the oxygen atoms of both vanadium and boron centres. However, compounds 2 and 3 correspond to more complicated structures, constructed from the same polyoxometalate clusters, which are interconnected by [Cu(en)2]2+ moieties via the terminal oxygen atoms of the polyoxoanions, generating one-dimensional structures. The functionalization of this polyoxovanadium borate cluster has been obtained by the use of [Cu(en)2]2+ complex ions, thus demonstrating the capacity of the terminal oxygen atoms of the cluster to bind transition metal centres. The structural stability of the [V12B18O60H6] cluster permits the formation of functionalized polyoxometalate clusters, generating various crystalline lattices.