Reactivity of a Sterically Hindered Fe(II) Thiolate Dimer with Amines and Hydrazines

The sterically hindered Fe(II) thiolate dimer Fe2(μ-STriph)2(STriph)2 (1; [STriph]− = 2,4,6-triphenylbenzenethiolate) reacts with primary amines (tBuNH2, aniline) and N2H4 to form the structurally characterized addition complexes Fe(STriph)2(NH2tBu)2, Fe2(μ-STriph)2(STriph)2(NH2Ph)2, and Fe2(μ-η1:η1-N2H4)2(N2H4)4(STriph)4 in high yield. Chemical and NMR spectroscopic evidence indicate that the binding of these nitrogen donors is labile in solution and multispecies equilibria are likely. With arylhydrazines, 1 catalytically disproportionates 1,2-diphenylhydrazine to aniline and azobenzene, and it rearranges 1-methyl-1,2-diarylhydrazines to give, after treatment with alumina, mononuclear, trigonal bipyramidal Fe(III) complexes of composition Fe(ISQ)2(STriph), where [ISQ]− denotes an appropriately substituted bidentate o-diiminobenzosemiquinonate ligand. Complex 1 shows no reaction with hindered 1,2-dialkylhydrazines (isopropyl or tert-butyl) or tetrasubstituted 1,2-dimethyl-1,2-diphenylhydrazine.