Structural and thermodynamic characteristics of adducts of silicon tetrahalides with 2,2′-bipyridine and 1,10-phenanthroline were calculated by the DFT B3LYP method. The enthalpies of sublimation of SiCl ₄·2,2′-bipyridine, reconstruction energies for donor and acceptor fragments, and energies of Si-N bonds in the complexes under consideration were estimated using the data obtained. These characteristics were compared with similar data for pyridine complexes. The chelate effect on the energy of Si-N bonds upon replacement of pyridine by 2,2′-bipyridine and 1,10-phenanthroline was discussed. The significant reconstruction of the bidentate donor upon the complex formation levels off the chelate effect.