Transition Moments of Visible Region Absorption Bands of trans(Cl)-Triammineaquadichlorocobalt(III) Chloride

Abstract

From single crystals of trans(Cl)-[CoCl2(NH3)3(H2O)]Cl, thin sections with different orientations and different thicknesses were prepared, and their polarized absorption spectra were examined in the 350–850 nm region using a microspectrophotometer. Two absorption peaks, caused by the (x2−y2 ← xy)-type transitions of the d-electrons of Co, were found: a 15750 cm−1 peak was assigned to overlapping A2 ← A1 and B2 ← A1 type transitions of the complex ion with C2v symmetry; a 19210 cm−1 peak was assigned to a B1 ← A1 type transition. The molar extinction coefficients (ε) were determined at each of these peaks: ε(||c) = 104 and ε (⊥c) = 16 l cm−1 mol−1 at 15750 cm−1, and ε(||c) = 5 and ε(⊥c) = 54 l cm−1 mol−1 at 19210 cm−1. These ε values were explained by taking distortions of the d-electron orbitals into consideration, that are partly caused by the oxygen atom coordination and partly by some vibronic couplings between the d-electron orbitals and cobalt-ligand stretching vibrations.

Crystal Structures and Hydrogen Bonding of Two Complexes containing the [Ammine‐chlorido‐ethylenediamine‐bis(pyridine)cobalt(III)]2+ Cation

“…Dichrochloride played a key role as starting material in Alfred Werner 's fundamental studies on octahedral cobalt(III) complexes . Subsequently, it served as a valuable intermediate for the preparation of many triamminecobalt(III) complexes, which usually cannot be made from the sparingly soluble non‐electrolyte precursor mer ‐trinitrotriamminecobalt(III) …”