New Approach to the Chemistry of Technetium(V) and Rhenium(V) Phenylimido Complexes: Novel [M(NPh)PNP]3+ Metal Fragments (M = Tc, Re; PNP = Aminodiphosphine) Suitable for the Synthesis of S

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• 作者：Marina Porchia ; Francesco Tisato ; Fiorenzo Refosco ; Cristina Bolzati ; Mario Cavazza-Ceccato ; Giuliano Bandoli ; and Alessandro Dolmella
• 刊名：Inorganic Chemistry
• 出版年：2005
• 出版时间：June 27, 2005
• 年：2005
• 卷：44
• 期：13
• 页码：4766 - 4776
• 全文大小：193K
• 年卷期：v.44,no.13(June 27, 2005)
• ISSN：1520-510X

文摘

Ligand-exchange reactions of the aminodiphosphine ligand bis[(2-diphenylphosphino)ethyl]amine hydrochloride (PNHP·HCl) with labile M(NPh)Cl₃(PPh₃)₂ precursors (M = Re, Tc) in the presence of triethylamine yield monocationicphenylimido mer,cis-[M(NPh)Cl₂(PNHP)]Cl (M = Re, 1; Tc, 2) intermediate complexes. X-ray analyses show thatin both compounds the aminodiphosphine acts as a tridentate ligand dictating a mer,cis arrangement. Two chlorideligands, respectively in an equatorial and in the axial position trans to the linear M-NPh moiety, fill the remainingpositions in a distorted-octahedral geometry. The chloride trans to the metal-imido core is labile, and is replacedby an alcoholate group, without affecting the original geometry, as established in mer,cis-[Re(NPh)(OEt)Cl(PNHP)]Cl 4. Otherwise, ligand-exchange reactions involving the aminodiphosphine bis[(2-diphenylphosphino)ethyl]methylamine(PNMeP), in which the central secondary amine has been replaced by a tertiary amine function, or its hydrochloridesalt (PNMeP·HCl) give rise to three different species, depending on the experimental conditions: fac,cis-[Re(NPh)Cl₂(PNMeP)]Cl 3a, cis,fac-Re(NPh)Cl₃(PNMeP)·HCl 3b, and mer,trans-[Re(NPh)Cl₂(PNMeP)]Cl 3c, which arecharacterized in solution by multinuclear NMR studies. The monodentate groups incorporated in these intermediatecompounds, either halides and/or ethoxide, undergo substitution reactions with bidentate donor ligands such ascatechol, ethylene glycol, and 1,2-aminophenol to afford stable mixed ligand complexes of the type [M(NPh)(O,O-cat)(PNP)]Cl [PNP = PNHP M = Re 5, Tc 6; PNP = PNMeP M = Re 7], [Re(NPh)(O,O-gly)(PNP)]Cl [PNP =PNHP 8, PNMeP 9] and [Re(NPh)(O,N-ap)(PNMeP)]Cl 10. X-ray diffraction analyses of the representative compounds5 and 8 reveal that the aminodiphosphine switches from the meridional to the facial coordination mode placing theheteroatom of the diphosphine trans to the phenylimido unit and the bidentate ligand in the equatorial plane.Solution-state NMR studies suggest an analogous geometry for 6, 7, 9, and 10. Comparison with similar mixedligand complexes including the terminal nitrido group is discussed.