LASER VAPORIZATION GENERATION OF THE DIATOMIC RADICALS PDB, (PDB)-PD-105, PDAL, AND (PDAL)-PD-105 - ELECTRON-SPIN-RESONANCE INVESTIGATION IN NEON MATRICES AT 4-K

The new diatomic radicals PdB and PdAl have been generated by depositing the products produced from the pulsed laser vaporization of the elemental mixtures into neon matrices at 4 K. ESR (electron spin resonance) studies of these matrix isolated radicals, including an analysis of the Pd-105(I = 5/2), Al-27(I = 5/2) and B-11(I = 3/2) nuclear hyperfine interactions, show that both have X 2-SIGMA electronic ground states. These new results are compared with previous ESR measurements for PdH, PdCH3, YPd, ScPd, and PdH2+ to reveal electronic structure information and bonding trends as the complexity of the ligand increases 1s, 2p, 3p, 3d, and 4d. Ab initio UHF (unrestricted Hartree-Fock) theoretical calculations were also conducted on four of these small palladium radicals as part of this experimental investigation. A simple interpretation of the Pd-105 hyperfine interactions and molecular g tensors based on the degree of charge transfer to palladium is presented. The observed magnetic parameters (MHz) for (PdB)-Pd-105-B11 in a neon matrix at 4 K are g(parallel-to) = 2.009(2), g(perpendicular-to) = 2.042(2), A(parallel-to) = - 1483(15), and A(perpendicular-to) = - 1483(2) for Pd-105, and A(parallel-to) = 197(4) and A(perpendicular-to) = 140(1) for B-11. The parameters for (PdAl)-Pd-105-Al-27 are g(parallel-to) = 2.010(l), g(perpendicular-to) = 2.0343(5), A(parallel-to) = - 1283(10) and A(perpendicular-to) = - 1268(2) for Pd-105, and A(parallel-to) = 182(2) and A(perpendicular-to) = 84.6(5) for Al-27.