Technetium and Rhenium in Five-Coordinate Symmetrical and Dissymmetrical Nitrido Complexes with Alkyl Phosphino-thiol Ligands. Synthesis and Structural Characterization

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• 作者：Cristina Bolzati ; Mario Cavazza-Ceccato ; Stefania Agostini ; Francesco Tisato ; Giuliano Bandoli
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：December 15, 2008
• 年：2008
• 卷：47
• 期：24
• 页码：11972-11983
• 全文大小：297K
• 年卷期：v.47,no.24(December 15, 2008)
• ISSN：1520-510X

文摘

The reactivity of bulky alkylphosphino-thiol ligands (PSH) toward nitride-M(V, VI) (M = Tc/Re) precursors was investigated. Neutral five-coordinate monosubstituted complexes of the type [M(N)(PS)Cl(PPh₃)] (Tc1−4, Re1−2) were prepared in moderate to high yields. It was found that these [M(N)(PS)Cl(PPh₃)] species underwent ligand-exchange reactions under mild conditions when reacted with bidentate mononegative ligands having soft donor atoms such as dithiocarbamates (NaLⁿ) to afford stable dissymmetrical mixed-substituted complexes of the type [M(N)(PS)(Lⁿ)] (Tc5,8−10, Re5−9) containing two different bidentate chelating ligands bound to the [MN]²⁺ moiety. In these reactions, the dithiocarbamate replaced the two labile monodentate ligands (Cl and PPh₃) leaving the [M(N)(PS)]⁺ building block intact. In the above reactions, technetium and rhenium were found to behave in a similar way. Instead, under more drastic conditions, reactions of PSH with [M(N)Cl₂(PPh₃)₂] gave a mixture of monosubstituted [M(N)(PS)Cl(PPh₃)] and bis-substituted species [M(N)(PS)₂] (Tc11−14) in the case of technetium, whereas only monosubstituted [M(N)(PS)Cl(PPh₃)] complexes were recovered for rhenium. All isolated products were characterized by elemental analysis, IR and multinuclear (¹H, ¹³C, and ³¹P) NMR spectroscopies, ESI MS spectrometry, and X-ray crystal structure determination of the representative monosubstituted [Tc(N)(PStbu)Cl(PPh₃)] (Tc4) and mixed-substituted [Re(N)(PScy)(L³)] (Re7) and [Re(N)(PSiso)(L⁴)] (Re9) complexes. The latter rhenium complexes represent the first example of a square-pyramidal nitrido Re species with the basal plane defined by a PS₃ donor set. Monosubstituted [M(N)(PS)Cl(PPh₃)] species bearing the substitution-inert [M(N)(PS)]⁺ moieties act as suitable building blocks proposed for the construction of new classes of dissymmetrical nitrido compounds with potential application in the development of essential and target specific ^99mTc and ¹⁸⁸Re radiopharmaceuticals for imaging and therapy, respectively.