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

Abstract

This article describes the synthesis and characterization of two polyoxometalate based ion-pair compounds [Co III(L)(NO 2) 2] 2[Mo 6O 19] ( 1) and [Co III(L)(NCS) 2] 2[W 6O 19]·2CH 3CN ( 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.