The ties that bind: The electrostatic potential of quadruply bonded W 2(hpp)4 and its cation support the idea that the very low ionization energies are due to excitations from the metal-metal bonding core. Theoretical MRCI computations based on CASSCF orbitals show that the relativistic effect influences the lowest four ionization energies, leading to distinct IE sequences: IE < IEπ < IE in W 2(hpp)4, and IE < IE < IEπ in Mo 2(hpp)4.
- ionization potentials
- metal-metal bonds
- multi-reference configuration interactions
- quadruple bonds
- relativistic effects