Monoanionic {Mn(NO)}⁵ and Dianionic {Mn(NO)}⁶ Thiolatonitrosylmanganese Complexes: [(NO)Mn(L)₂]⁻ and [(NO)Mn(L)₂]²⁻ (LH₂ = 1,2-Benzenedithiol and Toluene-3,4-dithiol)

The reaction of MnBr2 and [PPN]2[S,S-C6H3-R] (1:2 molar ratio) in THF yielded [(THF)Mn(S,S-C6H3-R)2]− [R = H (1a), Me (1b); THF = tetrahydrofuran]. Formation of the dimeric [Mn(S,S-C6H3-R)2]22− [R = H (2a), Me (2b)] was presumed to compensate for the electron-deficient MnIII core via two thiolate bridges upon dissolution of complexes 1a and 1b in CH2Cl2. Complex 2a displays antiferromagnetic coupling interaction between two MnIII centers (J = −52 cm−1), with the effective magnetic moment (μeff) increasing from 0.85 μB at 2.0 K to 4.86 μB at 300 K. The dianionic manganese(II) thiolate complexes [Mn(S,S-C6H3-R)2]2− [R = H (3a), Me (3b)] were isolated upon the addition of [BH4]− into complexes 1a and 1b or complexes 2a and 2b, respectively. The anionic mononuclear {Mn(NO)}5 thiolatonitrosylmanganese complexes [(NO)Mn(S,S-C6H3-R)2]− [R = H (4a), Me (4b)] were obtained from the reaction of NO(g) with the anionic complexes 1a and 1b, respectively, and the subsequent reduction of complexes 4a and 4b yielded the mononuclear {Mn(NO)}6 [(NO)Mn(S,S-C6H3-R)2]2− [R = H (5a), Me (5b)]. X-ray structural data, magnetic susceptibility measurement, and magnetic fitting results imply that the electronic structure of complex 4a is best described as a resonance hybrid of [(L)(L)MnIII(NO•)]− and [(L)(L•)MnIII(NO−)]− (L = 1,2-benzenedithiolate) electronic arrangements in a square-pyramidal ligand field. The lower IR vNO stretching frequency of complex 5a, compared to that of complex 4a (shifting from 1729 cm−1 in 4a to 1651 cm−1 in 5a), supports that one-electron reduction occurs in the {(L)(L•)MnIII} core upon reduction of complex 4a.