412304-56-4Relevant articles and documents
Chelated hydrazido(3-)rhenium(V) complexes: On the way to the nitrido-M(V) core (M = Tc, Re)
Mevellec, Franck,Lepareur, Nicolas,Roucoux, Alain,Noiret, Nicolas,Patin, Henri,Bandoli, Giuliano,Porchia, Marina,Tisato, Francesco
, p. 1591 - 1597 (2002)
Neutral and asymmetrical hydrazido(3-)rhenium(V) heterocomplexes of the type [Re(η2-L4)(Ln)(PPh3)] (η2-L4 = NNC(SCH3)S; H2L1 = S-methyl β-N-((2-hydroxyphenyl)ethylidene)dithiocarbazate, 1, H2L2 = S-methyl β-N-((2-hydroxyphenyl)methylidene)dithiocarbazate, 2) are prepared via ligand-exchange reactions in ethanolic solutions starting from [ReV(O)Cl4]- in the presence of PPh3 or from [ReV(O)Cl3(PPh3)2]. The distorted octahedral coordination sphere of these compounds is saturated by a chelated hydrazido group, a facially ligated ONS Schiff base, and PPh3. Reduction-substitution reactions starting from [NH4][ReVIIO4] in acidic ethanolic mixtures containing PPh3 and H2Ln (or its dithiocarbazic acid precursor H3L4) produce another example of chelated hydrazido(3-) rhenium(V) derivative, namely [Re(η2-L4)Cl2(PPh3) 2], 3. On the contrary, the N-methyl-substituted dithiocarbazic acid H2L3 reacts with perrhenate to give the known nitrido complex [Re(N)Cl2(PPh3)2]. Rhenium(V) complexes incorporating the robust η2-hydrazido moiety represent key intermediates helpful for the comprehension of the reaction pathway which generates nitridorhenium(V) species starting from oxo precursors. An essential requirement for the stabilization of such chelated hydrazido-Re(V) units is the triple deprotonation at the hydrazine nitrogens, thereby providing efficient π-electron circulation in the resulting five-membered ring. The thermal stability of these units is affected by the nature of the anchoring donor, thione sulfur ensuring stronger chelation than nitrogen and oxygen. The η2-hydrazido complexes are characterized by conventional physicochemical techniques, including the X-ray crystal structure determination of 1 and 3.
Rhenium(V) and technetium(V) complexes with phosphoraneimine and phosphoraneiminato ligands
Hecht, Maren,Anaya, Sonia Saucedo,Hagenbach, Adelheid,Abram, Ulrich
, p. 3172 - 3180 (2008/10/09)
Air-stable rhenium(V) nitrido complexes are formed when [ReOCl 3(PPh3)2], [NBu4][ReOCl 4], or [NBu4][ReNCl4] are treated with an excess of silylated phosphoraneiminates of the composition Me 3SiNPPh3 or Ph2P(NSiMe3)CH 2PPh2 in CH2Cl2. Complexes of the compositions [ReNCl(Ph2PCH2PPh2NH) 2]Cl (1), [ReN(OSiMe3)(Ph2PCH 2PPh2NH)2]Cl (2) or [ReNCl2(PPh 3)2] (3) were isolated and structurally characterized. The latter compound was also produced during a reaction of the rhenium(III) precursor [ReCl3(PPh3)2(CH3CN) and Me3SiNPPh3. Nitrogen transfer from the phosphorus to the rhenium atoms and the formation of nitrido ligands were observed in all examples. All products of reactions with an excess of the potentially chelating phosphoraneiminate Me3SiNP(Ph2)CH2PPh 2 contain neutral Ph2PCH2PPh2NH ligands. The required protons are supplied by a metal-induced decomposition of the solvent dichloromethane. The Re-N(imine) bond lengths (2.055-2.110 A) indicate single bonds, whereas the N-P bond with lengths between 1.596 A and 1.611 A reflect considerable double bond character. An oxorhenium(V) phosphoraneiminato complex, the dimeric compound [ReOCl2(μ-N- Ph2PCH2PPh2N)]2 (4), is formed during the reaction of [NBu4][ReOCl4] with an equivalent amount of Ph2P(NSiMe3)CH2PPh2 in dry acetonitrile. The blue neutral complex with two bridging phosphoraneiminato units is stable as a solid and in dry solvents. It decomposes in solution, when traces of water are present. The rhenium-nitrogen distances of 2.028(3) and 2.082(3) A are in the typical range of bridging phosphoraneiminates and an almost symmetric bonding mode. Technetium complexes with phosphoraneimine ligands were isolated from reactions of [NBu4][TcOCl4] with Me3SiNPPh3, and [NBu4][TcNCl4] with Me3SiNP(Ph2)CH2PPh2. Nitrogen transfer and the formation of a five-coordinate nitrido species, [TcNCl 2(HNPPh3)2] (5), was observed in the case of the oxo precursor, whereas reduction of the technetium(VI) starting material and the formation of the neutral technetium(V) complex [TcNCl2(Ph 2PCH2PPh2NH)] (6) or [TcNCl(Ph 2PCH2PPh2NH)2]Cl (7) was observed in the latter case. Both technetium complexes are air stable and X-ray structure determinations show bonding modes of the phosphoraneimines similar to those in the rhenium complexes.
Co-ordination chemistry of S-methyl 2-methyldithiocarbazate and formation of [M≡N]2+(M = Tc or Re) species
Marchi, Andrea,Uccelli, Licia,Marvelli, Lorenza,Rossi, Roberto,Giganti, Melchiore,Bertolasi, Valerio,Ferretti, Valeria
, p. 3105 - 3109 (2007/10/03)
Reaction of [TcOCl4]- and [ReOCl3(PPh3)2] with S-methyl 2-methyldithiocarbazate [H2L = H2NNMeC(S)SMe] under mild conditions gave the oxo-technetium(V) and -rhenium(V) S,N-chelated complexes [MO(HL)2]Cl (M = Tc or Re). These were transformed to the corresponding nitrido-complexes [MNCl2(PPh3)2] under reflux and in the presence of HCl and PPh3. The technetium(IV) complex [TcCl4(PPh3)2] under reflux and in presence of an excess of H2L and NEt3 gave the nitrido-compound [TcN(HL)2]. This was also obtained when [TcNCl2(PPh3)2] was used as precursor in the presence of NEt3. The complex [TcNCl2{NPr(CH2CH2PPh2) 2}] reacted with an excess of H2L to give the monosubstituted compound [TcN(HL){NPr(CH2CH2PPh2)2}]X (X = Cl, BF4 or BPh4). A crystal structure determination of the complex [ReO(HL)2]Cl showed a distorted square-pyramidal geometry with the oxygen atom in apical position. The Cl- ion is bound to NH groups by means of two hydrogen bonds. A set of reactions using 99mTc were carried out in order to understand the formation of the 99mTcN core.
