DFT study of H-H activation by Cp-2 LnH d(0) complexes

The energy required to activate the H-H bond in the entire series of Cp(2)L nH complexes has been calculated by DFT (B3PW91) methods. The activation en ergies have been calculated to vary from 0.5 to 8.0 kcal.mol(-1), indicatin g an overall facile reaction. The electronegativity of the lanthanide in it s most stable oxidation state is suggested to be a leading factor for inter preting the trends in activation energy. The geometry of the transition sta te is best viewed as an almost linear H-3(-) ligand with short H-H distance s and strong M-H interaction, through the wingtip H centers, with Ln. The e xchange reaction is thus established to be a sigma bond metathesis reaction .