Both 1:1 and 1:2 molecular complexes of (CH3)(2)Zn with NH3, PH3, AsH3, H2O, H2S, and H2Se have been formed, isolated, and characterized in argon matrices and cryogenic thin films. The reactivity of these systems varied greatly, from very rapid with H2S and H2Se to very slow (and low product yield) for PH3 and AsH3. Infrared spectra of these complexes showed perturbations to a number of vibrational modes of the acid and base subunits, the most sensitive of which was the intense ZnC2 antisymmetric stretch near 600 cm(-1). This mode shifted between 8 and 34 cm(-1) to the red in the different complexes; the shifts correlated well with the proton affinities of the bases. Cryogenic thin film experiments permitted initial formation and trapping of the 1:1 complex, while warming the film led in some cases) to 1:2 complex formation and then ultimately dissociation. The dissociation temperature correlated well with the shift of the ZnC2 antisymmetric stretch, suggesting that both are related to the bond strength in the complex.