Laser vaporization/rare gas matrix-isolation electron spin resonance studies of PdH+2, PdD+2, PdH, and PdD: Theoretical investigation of PdH+2
Knight, L. B.; Cobranchi, S. T.; Herlong, J. O.; Kirk, T. J.; Balasubramanian, K.; Das, K. K. Laser vaporization/rare gas matrix-isolation electron spin resonance studies of PdH+2, PdD+2, PdH, and PdD: Theoretical investigation of PdH+2. J. Chem. Phys. 1990, 92, 2721-2721.
The reactive laser vaporization of palladiummetal in the presence of H2(g) has been used to generate and trap neutral and charged palladium hydride radicals in neon and argon matrices for electron spin resonance investigations. The radicals identified are: 0PdH+ 2, 1 0 5PdH+ 2, 0PdD+ 2, 1 0 5PdD+ 2, 0PdH, 0PdD, 1 0 5PdH, and 1 0 5PdD. The electron spin resonance results prove that the H atoms are equivalent in PdH+ 2 but it cannot be determined for certain whether a highly bent 2 A 1ground state complex or a linear 2Î£ state is being observed, although the evidence seems to favor the 2 A 1 state. The observed nuclear hyperfineproperties (A and g tensors) are best accounted for by assigning the unpaired electron predominantly to 4d 2 z /5s orbitals on the metal in PdH+ 2 with only about 3% of the spin density on each H atom. Electron spin resonance results for PdH constitute the first observations for a diatomic metal hydride radical trapped in a neon matrix. The magnetic parameters (MHz) for 1 0 5PdH+ 2 in a neon matrix at 4 K are: g -Š¥=2.568(2); g -ˆ¥-‰‚1.92; A -Š¥(1 0 5Pd)=-ˆ’713(2); A -ˆ¥(1 0 5Pd)=-ˆ’688(15); A -Š¥(H)=45(1). Multireference SCF (MCSCF) and configuration interaction (CI) calculations were conducted for PdH+ 2 to calculate the energies and gross population distributions in the lowest-€lying electronic states. The lowest of these, the 2 A 1 state, has a calculated stabilization energy of 9.3 kcal/mol relative to Pd+(4d 9)+H2.
Journal of Chemical Physics