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Journal of Structural Chemistry

2013 year, number Приложение 1

AN EPR STUDY OF THE TRANSFORMATION OF Ni(cyclam)@CB[8] AND Ni(cyclen)@CB[8] INCLUSION COMPOUNDS DURING ANNEALING IN A HYDROGEN ATMOSPHERE

V. A. Nadolinnyi, A. S. Berezin, V. V. Bakovets, E. A. Kovalenko
A. V. Nikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences
Keywords: nickel cyclen, nickel cyclam, cucurbit[8]uril, EPR spectroscopy, nickel clusters

Abstract

The transformation is studied of the compounds {[Ni(cyclam)]@CB[8]}Cl2·16H2O and {cis-[Ni(cyclen)(H2O)Cl]@CB[8]}Cl×12H2O during thermal annealing in a temperature range of 20 °C to 340 °C. Using EPR spectroscopy, {cis-[Ni(cyclen)(H2O)Cl]@CB[8]}Cl×12H2O, Ni is found to reduce to the 3d9 state during annealing in a hydrogen atmosphere yet oxidize to the 3d 7 state in the air at 20°C. In the case of {[Ni(cyclam)]@CB[8]}Cl2×16H2O, nickel ions remain in the 3d8 state after annealing in a hydrogen atmosphere and make a transition to the 3d7 state after air pumping. In both cases, annealing in a hydrogen atmosphere leads to the decomposition of the nickel complexes; simultaneously, a single line with g = 2.003 appears in the EPR spectra, which is likely to be due to the resulting metal nickel clusters.