GAS-PHASE REACTIVITY OF (C5H5MG)(- AN EXPERIMENTAL AND THEORETICAL-STUDY() COMPLEXES )

The gas-phase reactivity of C5H5Mg+ complexes generated from ionized m agnesocene (Cp)(2)Mg.+ have been investigated by means of tandem mass spectrometry. Decomposition of metastable C5H5Mg+ ions involves the me tal-ligand dissociation and a hydrogen atom elimination leading to the formation of Mg+ and C5H4-Mg.+ ions. Collisional activation induces f urther fragmentations, yielding C3H3Mg+ and C3H2Mg.+ ions. To have som e insight into the structure and energetics of these four series of co mplexes, high-level ab initio calculations (G2(MP2)) have been perform ed. In addition, the nature of the metal ion-ligand interaction, the c harge distribution, as well as the characterization of orbitals involv ed in relevant systems have been analyzed by using the atoms in molecu les theory (AIM) of Bader and the natural bond orbital (NBO) analysis. The Cp-.... Mg+ binding energy has been estimated to be 74.0 kcal/mol , over the cyclopentadienyl geometry optimized at the CASSCF level bot h for B-2(1) and (2)A(2) electronic states.