- [{ReN(Me2PhP)(Et2dtc)Cl}2{ReN(Et 2dtc)2}2{SbCl3}2] - A novel tetranuclear rhenium complex with asymmetric nitrido bridges
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The reaction of [ReN(Et2dtc)2(Me2PhP)] (Me2PhP = dimethylphenylphosphine, Et2dtc- = diethyldithiocarbamate) with SbCl3 in dichloromethane results in the formation of [{ReN(Me2PhP)(Et2dtc)Cl}2{ReN(Et 2dtc)2}2{SbCl3}2]. A {Re≡N-}4 ring with asymmetric nitrido bridges is stabilised by the co-ordination of SbCl3 onto the chloro ligands and sulphur atoms of the dithiocarbamates. The compound decomposes upon heating in acetonitrile and the fragments of the tetrameric complex re-arrange to form [ReN(Me2PhP)(Et2dtc)Cl]4 and [ReN(Et2dtc)2]. The multinuclear rhenium compounds have been studied by X-ray crystallography. The 8-membered {Re≡N-}4 ring system in [{ReN(Me2PhP)(Et2dtc)Cl}2{ReN(Et 2dtc)2}2{SbCl3}2] is almost planar, while that of [ReN(Me2PhP)(Et2dtc)Cl]4 is clearly V-shaped when viewed down either diagonal Re...Re axis. A dihedral angle of 47.88(2)° has been found between the contributing planes.
- Stelzer,Hagenbach,Abram
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- Technetium and rhenium in five-coordinate symmetrical and dissymmetrical nitrido complexes with alkyl phosphino-thiol ligands. Synthesis and structural characterization
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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)CI(PPh 3)] (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 [M≡N]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)Cl 2(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 PS 3 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.
- Bolzati, Cristina,Cavazza-Ceccato, Mario,Agostini, Stefania,Tisato, Francesco,Bandoli, Giuliano
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p. 11972 - 11983
(2009/05/30)
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- Nitrido-technetium and -rhenium Complexes with Chelating Phosphines: Synthesis, Reactivity and Crystal Structures
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Nitrido-technetium(V) and -rhenium(V) complexes of general formula 1), 1,8-bis(diphenylphosphino)-3,6-dioxaoctane (L2) or 1,1,1-tris(diphenylphosphinomethyl)ethane (L3)> have been synthesized and characterized.They were prepared by the reduction of VINCl4>(1-) or by the replacement of the two triphenylphosphines of (M = Re or Tc) by bidentate or tripodal polyphosphine ligands L.Reaction of these complexes with an excess of potassium O-ethyl dithiocarbonate yields neutral dithiocarbonate compounds , while cationic and neutral complexes (1+) and were obtained upon reaction with K(S2CNEt2).The crystal structures of 1> and 2> have been determined by X-ray crystallography; the complex 1> shows square-pyramidal coordination at technetium with the Tc atom displaced from the basal plane towards the N atom by 0.410 Angstroem.An unusual trigonal-bipyramidal geometry is observed for 2>.The TcN bond distances (1.60 Angstroem) in both complexes are indicative of a strong triple bond.
- Marchi, Andrea,Marvelli, Lorenza,Rossi, Roberto,Magon, Luciano,Uccelli, Licia,et al.
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p. 1281 - 1286
(2007/10/02)
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