ESR OF TRANSITION METAL DIATOMIC IONS: $Mn^{+}_{2}$

$^{1}$ Similar to the procedure pioneered by L. B. Knight, Jr., Acc. Chem. Res. 19, 313 (1986). $^{2}$ R. J. Van Zee, C. A. Baumann, and W. Weltner, Jr., J. Chem. Phys. 78, 6977 (1981). $^{3}$ K. Ervin, S. K. Loh, N. Aristov, and P. B. Armentrout, J. Phys. Chem. 87, 3593 (1983).Author Institution: Department of Chemistry, University of FloridaThe molecular cation $^{55}Mn^{+}_{2}$ has been generated in an argon matrix at 4 K by simultaneous laser vaporization of manganese metal and open tube argon discharge $photoionization.^{1}$ Its ESR spectrum contains many fine structure lines, each apparently split by hyperfine interaction into 11 lines spaced 25 G apart, identifying two equivalent $^{55}Mn(I = 5/2)$ nuclei. Tentatively, it is a high-spin $^{12}\sigma$ molecule with a zero-field splitting parameter, D, of about $0.06 cm^{-1}$. This contrasts sharply with $Mn_{2}$ which has an ``antiferromagnetic'' $^{1}\sigma$ ground $state,^{2}$ but also a much weaker bond than $Mn^{+}_{2}.^{3}