ELECTRON-SPIN-RESONANCE INVESTIGATION OF SC2-STATE AS X(4)SIGMA- - COMPARISON WITH THEORETICAL CALCULATIONS( IN NEON MATRICES AND ASSIGNMENT OF ITS GROUND ELECTRONIC)

The discandium radical cation, Sc2+ has been isolated in neon matrices at 4 K and studied by electron spin resonance (ESR) spectroscopy and theoretical methods. It was produced by the x-irradiation of neon matr ix samples containing neutral Sc2 Which was formed by trapping the pro ducts generated from the pulsed laser vaporization of scandium metal. The experimental and theoretical findings indicate that Sc2+ has a 4SI GMA(g)- electronic ground state compared to an X5SIGMA(u)- state for t he neutral discandium radical. The large decrease in the Sc-45 hyperfi ne interaction (A tensor) going from Sc2 to Sc2+ provides direct exper imental information concerning the types of valence molecular orbitals that are involved in these diatomic radicals. The neon matrix magneti c parameters for (Sc2+)-Sc-45 are g(parallel-to) almost-equal-to 2.00, g(perpendicular-to) = 1.960(1), \A(parallel-to)\ = 28.(6), and \A(per pendicular-to)\ = 26.1(3) MHz; the D value (zero field splitting) was 15 381(3) MHz. Ab initio configuration interaction (CI) calculations o f the nuclear hyperfine interactions yielded results in reasonable agr eement with the experimental observations.