Dipole-bound anion of the HNNH3 isomer of hydrazine. An ab initio study

The possibility of electron binding to the HNNH3 and H2NNH2 tautomers of hy drazine was studied at the coupled cluster level of theory with single, dou ble, and noniterative triple excitations. The HNNH3 tautomer, with a dipole moment of 5.4 D, binds an electron by 1076 cm(-1) whereas the H2NNH2 tauto mer forms neither a dipole- nor valence-bound anionic state. It is suggeste d that the HNNH3 tautomer, which is kinetically stable but thermodynamicall y unstable relative to H2NNH2, may be formed by photodetachment from the N2 H4- species examined in this work.