화학공학소재연구정보센터
Inorganic Chemistry, Vol.42, No.8, 2504-2511, 2003
Structures and bonding of the sandwich complexes [Ti(eta(5)-E-5)(2)](2-) (E = CH, N, P, As, Sb): A theoretical study
Quantum chemical calculations using gradient-corrected DFT at the BP86/TZ2P level of the compounds [Ti(eta(5)-E-5)(2)](2-) (E = CH, N, P, As, Sb) are reported. The nature of the metal-ligand bonding has been analyzed with an energy decomposition method, and the results are compared with [Fe(eta(5)-E-5)(2)]. The bonding in both series of complexes is more covalent than electrostatic. The energy decomposition analysis shows that the dominant orbital interactions in the negatively charged titanium species come from the (e(2)') Ti --> [(eta(5)-E-5)(2)](2) back-donation (delta bonding) while the covalent bonding in the iron complexes come mainly from (e(1)') (Cp)(2) --> Fe2+ donation (pi bonding). The nature of the metal-ligand interactions does not change very much for different ligands cyc-E-5 within the two series of compounds. The calculated bond dissociation energies for breaking one metal-ligand bond of the molecules [Ti(eta(5)-E-5)(2)](2-) shows for E the order P > As > Sb much greater than N much greater than CH. The central message of this work is that the complexes [Ti(eta(5)-E-5)(2)](2-) are delta bonded molecules.