FIRST STRUCTURAL CHARACTERIZATION OF AN 8-COORDINATE COBALT(II) COMPLEX CONTAINING 5-MEMBERED CHELATE RINGS - EVIDENCE FOR D-ORBITAL SIGMA-STABILIZATION ENERGY FAVORING 8-COORDINATION OVER 6-COORDINATION AT COBALT(II) IONS
Wo. Koch et al., FIRST STRUCTURAL CHARACTERIZATION OF AN 8-COORDINATE COBALT(II) COMPLEX CONTAINING 5-MEMBERED CHELATE RINGS - EVIDENCE FOR D-ORBITAL SIGMA-STABILIZATION ENERGY FAVORING 8-COORDINATION OVER 6-COORDINATION AT COBALT(II) IONS, Chemical communications, (22), 1997, pp. 2237-2238
For the first time, an eight-coordinate cobalt(II) complex is presente
d where only five-membered chelate rings are formed with the coordinat
ed ligand; evidence is put forward that in addition to reasons of the
tetraazamacrocyclic nature of the ligand 2,11-diaza-[3.3](2,6)pyridino
phane (L), eight-coordination at cobalt(II) ions is, to some extent, f
avored with respect to six-coordination by the presence of d-orbital s
igma-stabilization energy as calculated by angular:overlap methods.