Syntheses of the Sixteen-Electron, Five-Coordinate Manganese — Chalcogenolate Complexes and π-Donating Ligands Metathesis Reaction
| Autor: | HSIEH CHIEN-KUO, 謝建國 |
|---|---|
| Rok vydání: | 2001 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 89 The preparation of the varieties of sixteen-electron five-coordinate manganese(I) complexes [Mn(CO)3(-EC6H4-o-NH-)]-(E=Te（4）, Se（1）, S（9）)、[Mn(CO)3(-EC6H4-o-E'-)]- (E=E'=S（6）；E=E'=O（7）；E=S, E'=O（8）)、 [Mn(CO)3(-SC8N2H4-o-S-)]- （10）by (a) oxidative decarbonylation addition of 2-aminophenyl dichalcogenides to anionic manganese(o)-carbonyl, and (b) π-donating ligand metathesis reaction of complex [Mn(CO)3(-TeC6H4-o-NH-)]-（4）proved successful appro- aches in this direction. X-ray structures show that geometry around Mn in complexes [Mn(CO)3(-EC6H4-o-NH-)]- (E=Te,Se,S) are between square pyramidal and trigonal bipyramidal. The short MnI-E and MnI-N bond lengths suggest that there is a partial π bonding formation between Mn(I) and the ligand [EC6H4-o-NH]2-. The IR νCO data of the coordinatively and electronically unsaturated complexes suggest the relative order of π-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- > [SC8N2H4-o-S]2-. Proton NMR spectra of the complexes（4）、（1）、（9）derivatives show the low-field shift of amide proton ( 1H NMR (C4D8O): δ 9.66(br) ppm (E=Te), 9.32(br) ppm (E=Se), 8.98(br) ppm (E=S)). Investigations of π-donating ligand metathesis reactions of complex [Mn(CO)3(-TeC6H4-o-NH-)]-（4）revealed that the stable intermediate, not the π-donating ability of bidentate ligands, is responsible for the final protonation/oxidation product. This argument is demonstrated by reaction of complex （4）with 1,2-benzenedithiol, hydroxythiophenol, and catechol, respectively, leading to the formation of complexes（6）、（7）、（8）, although any π-donor ligands containing the amide group is a more effective donor than any other π-donor lacking an amide group. Also, the reactions of complex（4）with electrophiles occurring at the more electron-rich amide site support that the more electron-rich amide donor of the chelating 2-tellurolatophenylamido occupies an equatorial site as indicated by a shorter MnI-N bond length of the distorted trigonal bipyramidal complex（4）. Additionally, the ability of a proton donor to precoordinate to the amide site must play an important role in these π-donating ligand metathesis reactions. This is particularly apparent when comparing EtOH/[NH2-C6 H4-o-NH2] to the [SH-C6H4-o-SH] reagents. The formation of the dimetallic [(CO)3Mn(μ-SC8N2H4-o-S-)]22- （16）can be interpreted as coordinative association of two units of unstable mononuclear [(CO)3Mn(-SC8N2H4-o-S-)]- （10）and reflects the π-donating ability of the bidentate ligand is responsible for the formation of pentacoordinate, sixteen-electron manganese(I) carbonyl complexes. Complex fac-[Fe(CO)3(TePh)3]- was employed as a “metallo chelating” ligand to synthesize the neutral (CO)3Mn(μ-TePh)3Fe(CO)3 （17）obtained in a one-step synthesis by treating fac-[Fe(CO)3(TePh)3]- with fac-[Mn(CO)3(CH3CN)3]+. It seems reasonable to conclude that the d6 Fe(II) [(CO)3Fe(TePh)3]- fragment is isolobal with the d6 Mn(I) [(CO)3Mn(TePh)3]2- fragment in complex （17）. This investigation shows that fac-[Fe(CO)3(TePh)3]- serves as a tridentate metallo ligand. The study also indicated that the fac-[Fe(CO)3(SePh)3]- may serve as a better tridentate metallo ligand than fac-[Fe(CO)3(TePh)3]- in the syntheses of heterometallic chalcogenolate complexes. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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