Four related compounds (CH3)(2)SiF2 (1), (CH3)(2)SiCl2 (2), (CH3)(2)GeF2 (3), and (CH3)(2)GeCl2 (4) were studied by ab initio quantum mechanical techniques to examine the deviation from the "ideal" tetrahedral geometry. Basis sets of double-zeta (DZ) quality were used, as well as DZ with the addition of a set of d-type functions on all heavy atoms (DZd). These bases were used in conjunction with the Hartree-Fock (HF) self-consistent field method and the single-and-double-excitation configuration interaction (CISD) method. Theoretical predictions corroborate electron diffraction results in that all four molecules have C-A-C bond angles significantly larger than 109 degrees 28’ but smaller than concluded from some analyses of electron diffraction data. Specifically, at the DZd/CISD level of theory, C-A-C bond angles of 115.9, 114.3, 120.9, and 117.6 degrees were found for molecules 1-4, respectively. An analysis also suggests that the 124 degrees experimental C-Ge-C bond angle for (CH3)(2)GeBr2 may be unrealistically large. Additionally, harmonic vibrational analyses at the HF level of theory have been completed to aid future studies of these four molecules.