Synthesis, spectroscopic and crystal field studies on some azido-chromium(III)-pyridine complexes

Abstract

The new complexes mer-Cr(py) 3(N 3) 3, NaCr(py) 4(N 3) 4, KCr(py) 4(N 3) 4, and RbCr(py) 3(N 3) 4 (py = pyridine) have been prepared. Infrared (4000-50 cm −1) and diffuse reflectance spectra (region 300-77 K) of powdered samples have been measured and discussed on bases of the known structures of these complexes. Single crystal absorption spectra for the mer-complex were obtained in the temperature range from 300 to 10 K revealing extensive vibronic structure associated with the 2 E g ( O h ) and 2 T 1 g ( O h ) electronic origins. Crystal field calculations were used to assign the bands in the vibronic region and to obtain estimates for the crystal field and Racah parameters for this class of substances. The parameters found for the mer-complex at 10 K are 10 Dq = 17906 cm −1, B = 387 cm −1 and C = 3381 cm −1.