2002 Volume 75 Issue 11 Pages 2407-2413
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.
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