Two new azide bound cobalt(III) complexes, [Co(L(1))(N3)3] (fac-1) and [Co(L(2))(N3)3] (mer-2), where L(1) is bis(2-pyridylmethyl)amine and L(2) is (2-pyridylmethyl)(2-pyridylethyl)amine, derived from tridentate reduced Schiff-base ligands have been reported. Interestingly, a methylene bridge regulated preferential coordination mode of ligands is noticed in their crystal structures: it is found...

Seven cobalt(III) complexes of the macrobicyclic tetraamine ligand [2(4).3(1)]adamanzane ([2(4).3(1)]adz) are reported along with the crystal structure of six of these complexes. The solid state and solution structures are discussed, and a detailed assignment of the NMR spectra of the sulfato complex is provided. Four of the seven complexes contain a chelate coordinating oxo-anion (sulfate, for...

Two novel pyridine pendant-armed macrocycles structurally reinforced by an ethyl bridge, either between adjacent nitrogens (for side-bridged) or non-adjacent nitrogens (for cross-bridged), have been synthesized and complexed with a range of transition metal ions (Co2+, Ni2+, Cu2+ and Zn2+). X-ray crystal structures of selected cross-bridged complexes were obtained which showed the characteristi...

The preparation and characterization of two mononuclear cobalt(III) tropocoronand complexes, [Co(TC-5,5)](BF4) and [Co(TC-6,6)](BPh4), are reported. The cobalt(III) centers exist in rare pseudotetrahedral conformations, with twist angles of 65° and 74° for the [Co(TC-5,5](+) and [Co(TC-6,6)](+) species, respectively. Structural and electrochemical characteristics are compared with those of newl...

Several cobalt complexes catalyze the evolution of hydrogen from acidic solutions, both homogeneously and at electrodes. The detailed molecular mechanisms of these transformations remain unresolved, largely owing to the fact that key reactive intermediates have eluded detection. One method of stabilizing reactive intermediates involves minimizing the overall reaction free-energy change. Here, w...