Synthesis and characterization of Co(III) complexes with 1,4,7,10-tetraazacyclotetradecane, -pentadecane, and -hexadecane

M. Tsuchimoto, Masakazu Kita, M. Nonoyama, J. Fujita

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New cobalt(III)-1,4,7,10-tetraazacyclotetradecane (N47), -pentadecane (N48), and -hexadecane (N49) complexes, trans-[CoCl2(N4x)]+ (x=7 (two isomers), 8 (two isomers), 9 (one isomer)), trans-[Co(NO2)2(N4x)]+ (x=7, 8, 9, one isomer), cis-[Co(NO2)2(N47)]+ (one isomer), and [Co(en)(N4x)]3+ (x=7, 8, one isomer) were synthesized and characterized. For analogous 1,4,7,10-tetraazacycloundecane (N46) complexes, two isomers for each of cis-[Co(NO2)2(N46)]+ and [Co(en)(N46)]3+ were also obtained and were found to isomerize to each other in acetonitrile. The ligand field parameters of nitrogen Δ(N) and chlorine Δ(Cl) estimated from the observed ligand field bands of trans-[CoCl2(N4x)]+ show a correlation between them; with an increase in ring size of N4x, the Δ(N) value decreases, while the Δ(Cl) value increases. The reduction potentials for each series of the dichloro, dinitro, and en complexes become less negative with an increase in ring size of N4x.

Original languageEnglish
Pages (from-to)227-234
Number of pages8
JournalBulletin of the Chemical Society of Japan
Issue number1
Publication statusPublished - 1990
Externally publishedYes


ASJC Scopus subject areas

  • Chemistry(all)

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