Title

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

ACS Citation

McKinley, A. J.; Karakyriakos, E.; Knight, L. B.; Babb, R. M.; Williams, A. Matrix-Isolation ESR Studies of the Various Isotopomers of the CH3Zn and ZnH Radicals: Comparisons with ab Initio Theoretical Calculations. J. Phys. Chem. A 2000, 104, 3528-3536.

Abstract

The 12CH3Zn, 12CH367Zn, 13CH3Zn, 13CH367Zn, 13CD367Zn, 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 Aiso(67Zn) and the Adip(67Zn) values calculated for both radicals were within 10% of the experimental observations. However, the calculated Aiso(13C) values for the CH3Zn radical were low by about 50%, and the calculated Aiso(H) value for ZnH was low by 60%. Density functional theory (DFT) yielded Aiso 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. The 12CH3Zn, 12CH367Zn, 13CH3Zn, 13CH367Zn, 13CD367Zn, 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 Aiso(67Zn) and the Adip(67Zn) values calculated for both radicals were within 10% of the experimental observations. However, the calculated Aiso(13C) values for the CH3Zn radical were low by about 50%, and the calculated Aiso(H) value for ZnH was low by 60%. Density functional theory (DFT) yielded Aiso 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.

Source Name

Journal of Physical Chemistry A

Publication Date

1-1-2000

Volume

104

Issue

16

Page(s)

137-142

Document Type

Citation

Citation Type

Article