Synthesis and spectroscopic characterization of cobalt(III)-alkyl amine complexes showing surface affinity: Single crystal X-ray structure determinations

Structurally integrated cobalt(III) complexes showing interesting surface affinity in the interfacial electron transfer reactions were synthesized by incorporating alkyl amines into the coordination sphere of cis-[Co(III)(en)(2)(RNH(2))Cl]Cl(2): (where RNH(2) = MeNH(2) (1), EtNH(2) (2), Pr(n)NH(2) (3), Bu(n)NH(2) (4), Bu(i)NH(2) (5). Pen(n)NH(2) (6), Hex(n)NH(2) (7) and BzNH(2) (8)) through a modified synthetic route. Such complexes are playing important role as electron acceptors in the interfacial electron transfer reactions taking place between metal complex and nanosized semiconductor particles in energy conversion schemes. The complexes were characterized by spectral, (1)H NMR and (13)C NMR techniques, which indicate the 1,2-diamino ethane site angles are closely similar forming five membered gauche configuration. Single crystal X-ray refinements were made to explore the structures of five complexes (2)-(5) and (7). The complexes under study crystallize either in monoclinic or orthorhombic structure and the space consists; (2) P2(1)/n, (3) P2(1)2(1)2(1), (4) Pbca, (5) P2(1) and (7) P2(1)/n. The Co(III) ion does not have an electronic preference, however, the structures reflect the conformational preference of RNH(2) ligand. (C) 2011 Elsevier B.V. All rights reserved.