Vibrational spectra of some isonitrile complexes of cobalt(I) and (II)

Abstract

The Raman and low-frequency infrared spectra of the trigonal-bipyramidal complexes Co(RNC)5ClO4(R = Me, Et, Ph) have been recorded and assigned. It is found that δ(CoCN) modes occur at higher frequencies than ν(Co—CN) modes. Although Raman spectra of the blue and yellow forms of Co(PhNC)5(ClO4)2 could not be obtained, the low-frequency infrared spectra are consistent with the C4v structure previously suggested (1). The dimeric complexes Co2(RNC)10(ClO4)4 (R = Me, Et) have been studied, and tentative assignments of the Raman and infrared spectra made on the basis of D4d symmetry. Spectra of the complexes Co2(RNC)10I(ClO4)3 (R = Me, Et) strongly support the previously suggested structural formulation (2) [(MeNC)5Co—I—Co(MeNC)5](ClO4)3, and furthermore indicate that the Co—I—Co skeleton is linear.