Inorganic-organic hybrid materials based on Co(III) tetra-aza-macrocyclic complexes and Lindqvist type poly-oxo anions: Synthesis, characterization and spectroscopy of [CoIII(L)(NO2)2]2 [Mo6O19] and [CoIII(L)(NCS)2]2[W6O19]•2CH3CN (L = Transdiene)

This article describes the synthesis and characterization of two polyoxometalate based ion-pair compounds [Co-III(L)(NO2)(2)](2)[Mo6O19] (1) and [Co-III(L)(NCS)(2)](2)[W6O19]center dot 2CH(3)CN (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. (C) 2011 Elsevier B.V. All rights reserved.