Discrete dinuclear cyano-bridged complexes.
The cyano-bridged complexes [L14CoIIINCFeII(CN)5]-, [L14CoIIINCFeIII(CN)5], [L15CoIIINCFeII(CN)5]-, and [L15CoIIINCFeIII(CN)5] (L14 = 6-methyl-1,4,8,11-tetraazacyclotetradecan-6- amine, L15 = 10-methyl-1,4,8,12-tetraazacyclopentadecan-10-amine) are prepared and characterized both structurally and spectroscopically. In each complex, the pendant amine is trans to the bridging CN ligand, as determined by spectroscopy and X-ray crystallography: Na(trans-[L14CoIIINCFeII(CN)5]).8H2O, monoclinic space group P2(1)/c, a = 15.58(1) A, b = 19.797(4) A, c = 19.830(6) A, beta = 91.62(4) degrees, Z = 8; trans-[L14CoIIINCFeIII(CN)5].4H2O, monoclinic space group P2(1)/m, a = 9.9690(9) A, b = 13.316(1) A, c = 10.1180(8) A, beta = 90.720(6) degrees, Z = 2; [L15CoIIINCFeIII(CN)5].4H2O, triclinic space group P1, a = 9.454(1) A, b = 9.778(1) A, c = 9.865(2) A, alpha = 60.37(1) degrees, beta = 62.60(1) degrees, gamma = 65.82(1) degrees, Z = 1. A precursor to the 14-membered macrocyclic complexes is prepared for the first time, and its crystal structure is also reported: trans-I [CoL14Cl](ClO4)2, orthorhombic space group Pbca, a = 11.833(3) A, b = 13.363(2) A, c = 26.015(2) A, Z = 8. These compounds form part of a novel series of discrete CN-bridged dinuclear compounds. The mixed-valent CoIII-FeII compounds exhibit metal-to-metal charge-transfer (MMCT) transitions in the region 510-530 nm.
Bernhardt
P V
PV
Department of Chemistry, University of Queensland, Brisbane 4072, Australia.
Macpherson
B P
BP
Martinez
M
M