The electronic structure of complexes arising from the formation of a double bond between a silylene ligand (Si(R)R') and a high-valent transition-metal fragment have been investigated using ab initio wave functions including the effects of electron correlation. Using the analogy of carbon, these complexes may be referred to as Scbrock-type silylenes or silylidenes. A prime motivation for this work is that complexes of this type, unlike their carbon analogues, have so far eluded attempts at experimental characterization. Several conclusions are reached as a result of these calculations. (a) The inclusion of electron correlation is necessary to adequately describe the MSi 1r-bond, while the MSi u-bond is adequately described at the Hartree-Fock level. (b) The GVB overlap (an indicator of kinetic stability) and MSi force constants (an indicator of thermodynamic stability) increase upon replacement of H with ligands (e.g., HnM=SiH2 - ClnM=SiH~ and substituent& (e.g., HnM=SiH2 - HnM=SiCl~ that are more electron withdrawing than H. (c) The MSi force constants are larger for the group VB silylidenes when compared to analogous group IVB silylidenes preceding them in the same row of the periodic table (i.e., Nb > Zr and Ta > Hf). (d) Analysis of the molecular and electronic structural data using the MC/LMO/CI approach leads to the conclusion that stronger MSi double bonds arise when the MSi 1r-bond is made more back-bonding in nature. The results suggest several strategies for synthesizing a silylidene which is stable enough to allow for experimental characterization.