Inorganic-organic hybrid materials based on Co(III) tetra-aza-macrocyclic complexes and Lindqvist type poly-oxo anions: Synthesis, characterization and spectroscopy of [Co < sup > III < /sup > (L)(NO < inf > 2 < /inf > ) < inf > 2 < /inf > ] < inf > 2 < /inf > [Mo < inf > 6 < /inf > O < inf > 19 < /inf > ] and [Co < sup > III < /sup > (L)(NCS) < inf > 2 < /inf > ] < inf > 2 < /inf > [W < inf > 6 < /inf > O < inf > 19 < /inf > ]·2CH < inf > 3 < /inf > CN (L = Transdiene)

Abstract

This article describes the synthesis and characterization of two polyoxometalate based ion-pair compounds [CoIII(L)(NO 2)2]2[Mo6O19] (1) and [CoIII(L)(NCS)2]2[W6O 19]·2CH3CN (2) (L = 5,7,7,12,14,14-hexamethyl-1,4, 8,11-tetraazacyclotetradeca-4,11-diene). They have been isolated by anionic metathesis of the respective perchlorate and thiocyanate salts with the Lindqvist type isopolyanions. The detailed spectroscopic (IR, UV-visible and ESR) analyses have been performed on compounds 1 and 2 along with their unambiguous crystal structure determination. The polyoxometalate cluster anions not only serve as the counter anions but are also involved in extensive non-covalent interactions with the macrocyclic cationic complexes in their respective crystals. Phase homogeneity of the synthesized compounds in bulk has been established by the X-ray powder diffraction study. Thermal analysis has also been carried out on the title compounds. © 2011 Elsevier B.V. All rights reserved.