Quantum mechanical ab inito methods are employed to study molecules contain germa-nium and phosphorus. The dependence of the relative energies of 116 diphosphene anddiphosphinylidene compounds on the modification of their structures is studied theoreti-cally. Optimized geometries and relative energies are reported for all structures. In the case of the substitution of both H atoms by lithoxy (OLi) or ONa groups is the diphosphinylidene type structure found to be lower in energy. This result is explained through the naturalpopulation analyses, where a very favorable coulombic attraction is found in the OLi sub-stituted diphosphinylidene structure. Next, a theoretical investigation of Ge2CH2 is carriedout. The singlet potential energy surface (PES) is systematically explored and energies wereobtained using theoretical methods including coupled cluster theory and focal point analy-sis (FPA). Eleven stationary points are located on the Ge2CH2 singlet ground state PES.Among them, seven structures are minima (1S7S). The global minimum is predicted to bethe hydrogen-bridged structure 1S.