Laser vaporization generation of the diatomic radicals PdB, 105PdB, PdAl, and 105PdAl: Electron spin resonance investigation in neon matrices at 4 K

Abstract

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 105Pd(I=5/2), 27Al(I=5/2), and 11B(I=3/2) nuclear hyperfine interactions, show that both have X 2Σ 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 105Pd hyperfine interactions and molecular g tensors based on the degree of charge transfer to palladium is presented. The observed magnetic parameters (MHz) for 105Pd11B in a neon matrix at 4 K are g∥=2.009(2), g⊥=2.042(2), A∥=−1483(15), and A⊥=−1483(2) for 105Pd, and A∥=197(4) and A⊥=140(1) for 11B. The parameters for 105Pd27Al are g∥=2.010(1), g⊥=2.0343(5), A∥=−1283(10) and A⊥=−1268(2) for 105Pd, and A∥=182(2) and A⊥=84.6(5) for 27Al.