Macrocyclic complexes : Synthesis and characterization of cobalt(II), nickel(II) and copper(II) complexes with [14]1,4,5,7,8,11,12,14-octaaza-2,3,9,10-tetraoxo-1,4,5,6,6,7,8,11,12,13,13,14-dodecahydrocyclotetradecane (OTCT)

School of Chemistry, Sambalpur University, Jyoti Vihar, Burla-768 019, Odisha, India G. M. College (Autonomous), Sambalpur, Odisha, India Department of Chemistry, Patna University, Patna-800 005, Bihar, India Manuscript received 16 June 2009, revised 18 March 2010, accepted 29 March 2010 A series of macrocyclic complexes of the titled ligand have been isolated by the action of formaldehyde (H2CO) on bis-(1,4-diamino-1,4-diaza-2,3-dioxobutanc) complexes of cobalt(II), nickel(ll) and copper(ll). The coordination template effect governs the steric course of the reaction. The structures of the complexes have been elucidated on the basis of IR, electronic, ESR spectral data, magnetic properties, electrochemical studies and thermal data. Electrochemical studies show that all the complexes show two well defined reduction curves corresponding to the formation of species where the metal ion can be formally assigned an oxidation state of + I and zero respectively