Syntheses, Reactivity, and -Donating Ligand Metathesis Reaction of Five-Coordinate Sixteen-Electron Manganese(I) Complexes: Crystal Str
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The preparation of the varieties of five-coordinate sixteen-electron manganese(I) complexes [Mn(CO)3(-EC6H4-o-E'-)]- (E = Te, Se, S, O; E' = NH, S, O) by (a) oxidative addition of 2-aminophenyl dichalcogenides toanionic manganese(0)-carbonyl, (b) -donating ligand metathesis reaction of complex [Mn(CO)3(-TeC6H4-o-NH-)]-, and (c) reduction /deprotonation of the neutral dimetallic [(Mn(CO)3)2(-SC6H4-o-S-S-C6H4-o--S-)]/[(CO)3Mn(-SC6H4-o-NH2-)]2 proved successful approaches in this direction. The IR CO data of thecoordinatively and electronically unsaturated [Mn(CO)3(-EC6H4-o-E'-)]- (E = Te, Se, S, O; E' = NH, S, O)complexes suggest the relative order of -donating ability of the series of bidentate ligands being [TeC6H4-o-NH]2- > [SeC6H4-o-NH]2- > [SC6H4-o-NH]2- > [SC6H4-o-S]2- > [SC6H4-o-O]2- > [OC6H4-o-O]2-. ProtonNMR spectra of the [Mn(CO)3(-EC6H4-o-NH-)]- (E = Te, Se, S) derivatives show the low-field shift of theamide proton (1H NMR (C4D8O): 9.66 (br) ppm (E = Te), 9.32 (br) ppm (E = Se), 8.98 (br) ppm (E = S)).The formation of the dimetallic [(CO)3Mn(-SC8N2H4-o-S-)]22- can be interpreted as coordinative associationof two units of unstable mononuclear [(CO)3Mn(-SC8N2H4-o-S-)]- and reflects the -donating ability of thebidentate ligand is responsible for the formation of pentacoordinate, sixteen-electron manganese(I) carbonylcomplexes. The neutral bimetallic manganese(I)-bismercaptophenyl disulfide complex [(Mn(CO)3)2(-SC6H4-o-S-S-C6H4-o--S-)] with internal S-S bond length of 2.222(1) Å and the five-coordinate sixteen-electron complex[Mn(CO)3(-SC6H4-o-S-)]- are chemically interconvertible. In a similar fashion, treatment of complex [Mn(CO)3(-SC6H4-o-NH-)]- with HBF4 yielded neutral dinuclear complex [(CO)3Mn(-SC6H4-o-NH2-)]2 and showedthat the amine deprotonation is reversible. Investigations of -donating ligand metathesis reactions of complex[Mn(CO)3(-TeC6H4-o-NH-)]- revealed that the stable intermediate, not the -donating ability of bidentate ligands,is responsible for the final protonation/oxidation product. This argument is demonstrated by reaction of [Mn(CO)3(-TeC6H4-o-NH-)]- with 1,2-benzenedithiol, hydroxythiophenol, and catechol, respectively leading tothe formation of [Mn(CO)3(-EC6H4-o-E'-)]- (E = S, O; E' = S, O), although any -donor containing theamido group is a more effective donor than any other -donor lacking an amido group. Also, the reactions of[Mn(CO)3(-TeC6H4-o-NH-)]- with electrophiles occurring at the more electron-rich amide site support that themore electron-rich amide donor of the chelating 2-tellurolatophenylamido occupies an equatorial site as indicatedby a shorter MnI-N bond length of the distorted trigonal bipyramidal [Mn(CO)3(-TeC6H4-o-NH-)]-.

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