Matrix-Isolation ESR Studies of the Various Isotopomers of the CH₃Zn and ZnH Radicals:  Comparisons with ab Initio Theoretical Calculations

Abstract

The 12CH3Zn, 12CH3 67Zn, 13CH3Zn, 13CH3 67Zn, 13CD3 67Zn, and 13CD3Zn radicals have been isolated in an inert neon matrix at 4.3 K. Their electronic structure has been probed for the first time using matrix-isolation electron spin resonance spectroscopy (MI-ESR). These radicals were generated by the reaction of laser-ablated zinc metal with the appropriate methyl precursor. The magnetic parameters (MHz) were determined to be g ⊥ = 1.9835(4), A ⊥(H) = 14(1), A ⊥(D) = 2.2(4), A ⊥(13C) = 166(3), and A ⊥(67Zn) = 547(1). Estimates were derived for A ∥(13C) = 211(50) and A ∥(67Zn) = 608(5). The 67ZnH radical was also generated by the reaction of laser-ablated zinc metal and hydrogen gas and studied for the first time by MI-ESR after isolation in solid neon matrixes at 4 K. The values of the 67ZnH magnetic parameters (MHz) were determined to be g ⊥ = 1.9841(3), g ∥ = 1.9990(5), A ⊥(H) = 505(1), A ∥(H) = 503(1), A ⊥(67Zn) = 615(1), and A ∥(67Zn) = 660(1). Earlier argon MI-ESR studies produced ZnH by conventional high-temperature methods and determined only the hydrogen hyperfine interaction and the molecular g tensor. Hartree−Fock single- and double-excitation configuration interaction (HFSDCI) and multireference single- and double-excitation configuration interaction (MRSDCI) ab initio calculations of the magnetic hyperfine interactions in the CH3Zn and ZnH radicals were performed. The A iso(67Zn) and the A dip(67Zn) values calculated for both radicals were within 10% of the experimental observations. However, the calculated A iso(13C) values for the CH3Zn radical were low by about 50%, and the calculated A iso(H) value for ZnH was low by 60%. Density functional theory (DFT) yielded A iso values for H and 13C in much closer agreement with experiment. A comparison is presented between the ESR results for the CH3Zn and ZnH radicals and their cadmium analogues, which have been investigated previously by MI-ESR.

Multi-isotopologue analyses of new vibration–rotation and pure rotation spectra of ZnH and CdH

“…These calculations further confirmed the experimental assignments of the A 2 P, B 2 R + , and C 2 R + states [33][34][35]. Hyperfine structure, K-doubling and lifetimes of ZnH and CdH have been measured by laser-induced fluorescence spectroscopy [36,37] and by matrix-isolation electron spin resonance (MI-ESR) techniques [38][39][40]. Low resolution infrared absorption spectra of ZnH, ZnD, CdH, and CdD trapped in solid argon, neon, and hydrogen matrices have also been recorded [41,42].…”

Dissociation of Methane on La2O3 Surfaces Doped with Cu, Mg, or Zn

“…The molecule ZnCH 3 has been identified, in the gas phase, by electronic spectroscopy and ESR measurements. 47,48 Our calculations on the gas-phase ZnCH 3 give a ZnÀC distance of 2.05 Å and a binding energy of À0.59 eV; the CÀZn distance in the ZnLa 2 O 3 system is 2.2 Å. A longer bond length between the carbon and the Zn dopant is expected, because the Zn atom in ZnLa 2 O 3 has additional bonds with the surface oxygen atoms as compared to the ZnCH 3 molecule.…”

Electron spin resonance studies of199HgH,201HgH,199HgD and201HgD isolated in neon and argon matrices at 4K: an electronic structure investigation

“…The most desirable approach is to evaluate A,,, and Adlp directly from a computed wavefunction-the strategy employed for numerous light-atom radical (neutrals and ions) studies conducted in collaboration with Professor E. R. Davidson and his associates using their MELDF program [21]. Recent examples include VOz [22], ScO [23] and ZnH [24].…”