INFRARED SPECTROSCOPIC CHARACTERIZATION OF MOLECULAR-COMPLEXES OF DIMETHYLCADMIUM WITH GROUP-V AND GROUP-VI HYDRIDES IN INERT MATRICES AND CRYOGENIC THIN-FILMS

Molecular complexes of (CH3)(2)Cd with H2S, H2Se, NH3, PH3 and AsH3 ha ve been formed, isolated and characterized in argon matrices and cryog enic thin films. Infrared spectra of the 1:1 and, in some cases, the 1 :2 complexes showed perturbations to a number of vibrational modes of the acid ((CH3)(2)Cd) and base subunits. Shifts between 6 and 22 cm(-1 ) to the red of the CdC2 antisymmetric stretch were noted, suggesting that these complexes are somewhat less strongly bound than analogous c omplexes of (CH3)(2)Zn. This conclusion is supported by the relatively small shift of the symmetric deformation mode of NH3 complexes to (CH 3)(2)Cd compared with many known complexes of NH3. Nonetheless, the ma gnitudes of the shifts correlate well with the proton affinities of th e bases employed here. Cryogenic thin film experiments involving (CH3) (2)Cd and NH3 permitted initial formation and trapping of the 1:1 comp lex, and warming the film from 14 K towards room temperature led to fo rmation of the 1:2 complex and then ultimately dissociation. The disso ciation temperature correlated well with the shift of the CdC2 antisym metric stretch, suggesting that both are related to the bond strength in the complex.