The Franck-Condon factors for nonradiative transitions from (MLCT)-M-3 excited states in 16 complexes of Re(I), Ru(II) and Os(II) with alpha-diimine ligands were estimated using ligand's geometry, vibrational frequencies and normal modes obtained by ab initio quantum chemical calculations. The linear correlation was obtained between logarithms of experimental constants of nonradiative transitions and theoretical Franck-Condon factors. (C) 2003 Elsevier Science B.V. All rights reserved.