POLARIZED TEMPERATURE-DEPENDENT SINGLE-CRYSTAL SPECTRA OF TRANSITION METAL $CHELATES^{*}$

$^{*}$Supported by NIH, NSF, University of Illinois Research Board, and an Alfred p. Sloan Research Fellowship.Author Institution: Noyes Chemical Laboratory, University of Illinois“Visible spectra of single crystals of metal chelates can be less completed than those of simple in one respect. The chelates, forming molecular crystals, are more apt to be describable by the oriented gas model. In centric chelates, the vibronic selection rules are not very restrictive and the polarized spectra thus do not afford reliable band assignments. However, temperature dependences of the band intensities may reveal which vibrations cause the important intensity-producing perturbations. Temperature-dependent, spectra of some 4- and 6- coordinated Cu and Ni chelates will be presented. Lowered temperature brings out new sharp bands in nickel chelates with imines; they are tentatively attributed to single-triplet transitions.