Theoretical study of the dipole-bound anion (HPPH3)(-)

The possibility of electron binding to the HPPH3 and H2PPH2 tautomers of di phosphine was studied at the coupled cluster level of theory with single, d ouble, and noniterative triple excitations. The HPPH3 tautomer, with a dipo le moment of 3.7 D, binds an electron by 333 cm(-1), whereas the H2PPH2 tau tomer forms neither a dipole- nor valence-bound anionic state. It is sugges ted that the HPPH3 tautomer, which is kinetically stable but thermodynamica lly unstable relative to H2PPH2, may be formed by photodetachment from the P2H4- species examined in this work. An unusual aspect of the (HPPH3)(-) an ion is that electron correlation contributes 82% to the electronic stabilit y and effects beyond the fourth order of the Moller-Plesset perturbation th eory contribute 55%. (C) 1999 American Institute of Physics. [S0021-9606(99 )31201-0].