Vertical and adiabatical ionization potentials of MHminus;K+1anions.Abinitiostudy of the structure and stability of hypervalent MHk+1molecules

摘要

Vertical and adiabatic ionization potentials of the free MHk+1minus;anions, where M is a nontransition atom andkis the maximal formal valence of the atom M, have been studied byabinitiomethods. Thermodynamic stabilities of the corresponding neutral hypervalent MHk+1species have been calculated as well. LiH2minus;, BeH3minus;, MgH3minus;, BH4minus;, AlH4minus;, and SiH5minus;are very stable to loss of the extra electron and are stable geometrically at high symmetry structure, except for SiH5minus;which is not stable thermodynamically. LiH2, NaH2, BeH3, MgH3, and BH4have minima at C2v(2B2) structures; however, only BH4is thermodynamically stable to all possible dissociation asymptotes. The NaH2minus;anion is not adiabatically electronically stable.