SYNTHESIS, SPECTROSCOPIC AND CRYSTAL-FIELD STUDIES ON SOME AZIDO-CHROMIUM(III)-PYRIDINE COMPLEXES

The new complexes mer-Cr(py)3(N3)3, NaCr(PY)4(N3)4, KCr(py)4(N3)4, and RbCr(py)3(N3)4 (py = pyridine) have been prepared. Infrared (4000-50 cm-1) and diffuse reflectance spectra (region 300-77 K) of powdered sa mples have been measured and discussed on bases of the known structure s of these complexes. Single crystal absorption spectra for the mer-co mplex were obtained in the temperature range from 300 to 10 K revealin g extensive vibronic structure associated with the 2E(g)(O(h)) and 2T1 g(O(h)) electronic origins. Crystal field calculations were used to as sign the bands in the vibronic region and to obtain estimates for the crystal field and Racah parameters for this class of substances. The p arameters found for the mer-complex at 10 K are 10 Dq = 17906 cm-1, B = 387 cm-1 and C = 3381 cm-1.