Aj. Mckinley et al., Matrix-isolation ESR studies of the various isotopomers of the CH3Zn and ZnH radicals: Comparisons with ab initio theoretical calculations, J PHYS CH A, 104(16), 2000, pp. 3528-3536
The (CH3Zn)-C-12, (CH3Zn)-C-12-Zn-67, (CH3Zn)-C-13, (CH3Zn)-C-13-Zn-67, (CD
3Zn)-C-13-Zn-67, and (CD3Zn)-C-13 radicals have been isolated in an inert n
eon matrix at 4.3 K. Their electronic structure has been probed for the fir
st time using matrix-isolation electron spin resonance spectroscopy (MI-ESR
). These radicals were generated by the reaction of laserablated zinc metal
with the appropriate methyl precursor. The magnetic parameters (MHz) were
determined to be g(perpendicular to) = 1.9835(4), A(perpendicular to)(H) =
14(1), A(perpendicular to)(D) = 2.2(4), A(perpendicular to)(C-13) = 166(3),
and A(perpendicular to)(Zn-67) = 547(1). Estimates were derived for A(para
llel to)(C-13) = 211(50) and A(parallel to)(Zn-67) = 608(5). The (ZnH)-Zn-6
7 radical was also generated by the reaction of laser-ablated zinc metal an
d hydrogen gas and studied fur the first time by MI-ESR after isolation in
solid neon matrixes at 4 K. The values of the 67ZnH magnetic parameters (MH
z) were determined to be g(perpendicular to) = 1.9841(3), g(parallel to) =
1.9990(5), A(perpendicular to)(H) = 505(1), A(parallel to)(H) = 503(1), A(p
erpendicular to)(Zn-67) = 615(1), and A(parallel to)(Zn-67) = 660(1). Earli
er argon MI-ESR studies produced ZnH by conventional high-temperature metho
ds and determined only the hydrogen hyperfine interaction and the molecular
a tensor. Hartree-Fock single- and double-excitation configuration interac
tion (HFSDCI) and multireference single- and double-excitation configuratio
n interaction (MRSDCI) ab initio calculations of the magnetic hyperfine int
eractions in the CH3Zn and ZnH radicals were performed. The A(iso)(Zn-67) a
nd the A(dip)(Zn-67) values calculated for both radicals were within 1% of
the experimental observations. However, the calculated A(iso)(C-13) values
for the CH3Zn radical were low by about 50%, and the calculated A(iso)(H) v
alue for ZnH was low by 60%. Density functional theory (DFT) yielded A(iso)
values for H and C-13 in much closer agreement with experiment. A comparis
on is presented between the ESR results for the CH3Zn and ZnH radicals and
their cadmium analogues, which have been investigated previously by MI-ESR.