Knowledge Bank

The molecular cation $\mathrm{<mrow\; data-mjx-texclass="ORD">55</mrow>}Mn2+$ 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 $\mathrm{<mrow\; data-mjx-texclass="ORD">55</mrow>}Mn(I=5/2)$ nuclei. Tentatively, it is a high-spin $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}\sigma$ molecule with a zero-field splitting parameter, D, of about $0.06cm-1$. This contrasts sharply with $Mn2$ which has an ``antiferromagnetic'' $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\sigma$ ground $state,2$ but also a much weaker bond than $Mn2+.3$