Hydrothermal syntheses and crystal structures of new cage-like mixed-valent polyoxovanadates

Three new cage-like mixed-valent polyoxovanadates [Ni(1,10'-phen)(3)](2)[V10O26] 1, [Zn(2,2'-biPY)(3)](3)[V15O36Cl](.)3H(2)O (2) and [Co(2,2'-biPY)(3)](3)[V15O36Cl](.)3H(2)O (3) have been hydrothermally synthesized for the first time and characterized by elemental analyses, IR, EPR spectra, TG analyses and single crystal X-ray diffraction. The polyoxoanion of I exhibits an interesting empty ellipsoidal [V-2(IV) V-8(V) O-26](4-) 'host' shell, while the oxo vanadium clusters of 2 and 3 possess a spherical [V-8(IV) V-7(V) O36Cl](6-) cage with a Cl- ion encapsulated. The structure-directing role of organic templates (1,10'-phen and 2,2'-bipy) on the formation of the polyoxoanion structures is discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.