Rhenium(V) and Technetium(V) Nitrido Complexes with Mixed Tridentate 蟺-Donor and Monodentate 蟺-Acceptor Ligands

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• 作者：Alessandra Boschi ; Emiliano Cazzola ; Licia Uccelli ; Micol Pasquali ; Valeria Ferretti ; Valerio Bertolasi ; Adriano Duatti
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：March 5, 2012
• 年：2012
• 卷：51
• 期：5
• 页码：3130-3137
• 全文大小：355K
• 年卷期：v.51,no.5(March 5, 2012)
• ISSN：1520-510X

文摘

Mixed-ligand [M(N)(SNS)(PPh₃)] complexes (M = Tc, Re) (1, 2) were prepared by reaction of the precursor [M(N)Cl₂(PPh₃)₂] with ligand 2,2鈥?dimercaptodiethylamine [H₂SNS = NH(CH₂CH₂SH)₂] in refluxing dichloromethane/ethanol mixtures. In these compounds, 2,2鈥?dimercaptodiethylamine acts as a dianionic tridentate chelating ligand bound to the [M鈮]²⁺ group through the two 蟺-donor deprotonated sulfur atoms and the protonated amine nitrogen atom. Triphenylphosphine completes the coordination sphere, acting as a monodentate ligand. [M(N)(NS₂)(PPh₃)] complexes can assume two different isomeric forms depending on the syn and anti orientations of the hydrogen atom bound to the central nitrogen atom of the SNS ligand with respect to the M鈮 moiety. X-ray crystallography of the syn isomer of complex 2 demonstrated that it has a distorted trigonal bipyramidal geometry with the nitrido group and the two sulfur atoms defining the equatorial plane, the phosphorus atom of the monophosphine and the protonated amine nitrogen of the tridentate ligand spanning the two reciprocal trans positions along the axis perpendicular to the trigonal plane. Synthesis of the analogous Tc derivatives with tris(2-cyanoethyl)phosphine, [Tc(N)(SNS)(PCN)] [(PCN = P(CH₂CH₂CN)₃], required the preliminary preparation of the new precursor [Tc(N)(PCN)₂Cl₂]₂ (3), which was prepared by reacting [n-NBu₄][Tc(N)Cl₄] with a high excess of PCN. The crystal structure of compound 3 consists of a noncrystallographic centrosymmetric dimer of Tc(V) nitrido complexes having an octahedral geometry. In this arrangement, the apical positions are occupied by two tris(2-cyanoethyl)phosphine groups and the equatorial positions by the nitrido group whereas the two Cl^{鈥?/sup> anions and one cyano ligand belong to the other octahedral component of the dimer. By reacting the new precursor [Tc(N)(PCN)₂Cl₂]₂ with the ligand H₂SNS the complex [Tc(N)(SNS)(PCN)] (5) was finally obtained in acetonitrile solution. The new Tc(III) complex trans-[Tc(PCN)₂Cl₄][n-NBu₄] (4) was also isolated from the reaction solution used for preparing complex 3 as side product and characterized by X-ray diffraction. The crystal structure of 4 consists of independent trans-[TcCl₄(PCN)₂]鈭?/sup> anions situated on crystallographic centers of symmetry and tetrabutylammonium cations in general positions.}