Joachim Stach

In(III), Tl(III) and V(IV) tris-chelates of the heterocyclic dithiolene and diselenolene ligands 1,3-dithiole-2-thione-4,5-dithiolate (dmit), 1,2-dithiole-3-thione-4,5-dithiolate (dmt) and 1,3-diselenole-2-selone-4,5-diselenolate (dsis). Crystal and molecular structure of (Bu4N)2 [V(dmt)3]

Abstract Synthesis and characterization of the first trischelates of the dichalcogenolene ligands 1,3-dithiole-2-thione-4,5-dithiolate (dmit), 1,2-dithiole-3-thione-4,5-dithiolate (dmt)and 1,3-diselenole-2-selone-4,5-diselenolate (dsis) with the central ions In(III), Tl(III) and V(IV) are reported. On (Bu4N)2[V(dmt)3] the first X-ray structure of a dithiolene tris-chelate containing unsymmetric ligand was carried out: the compound crystallizes monoclinic, space group P21/c, with four molecules in the unit cell; a = 16.264(3), b = 17.319(4), c = 21.554(4) A, β = 103.03(2)°. The ligand dmt causes a very low symmetry of the VS6 moiety in [V(dmt)3]2− having pseudo-meridional arrangement of the three ligands. The EPR parameters of the compounds (Bu4N)2[V(dmit)3] and (Bu4N)2[V(dmt)3] measured in liquid and frozen acetonic solution are compared with those of the tris(maleonitriledithiolato)vanadate(IV) anion supporting a geometry of the anion being between octahedral and trigonal prismatic.

[TcNBr4−pClp]− (p = 1–3) nitridotechnetate(VI) mixed-ligand complexes. An EPR study

Abstract The formation of mixed-ligand complexes of the type [TcNBr 4− p Cl p ] − ( p = 1–3) during the reaction between TcNBr 4 − and TcNCl 4 − is reported. Evidence of the individual mixed-ligand compounds is given by their EPR spectral data. In liquid as well as in frozen solution, a strong dependence of the EPR quantities on the composition of the coordination sphere could be detected. This is shown by a nearly linear dependence of g 0 , g ∥, a 0 Tc and A ∥ Tc on the spin-orbit coupling constants of the equatorial donors.

Lipophilic technetium complexes. III. Chelate complexes of technetium(V) containing the Tc-nitrido core

Etude de la formation des complexes [TcNL 2 ] 0,−2,+2 . Tres grande stabilite de la triple liaison Tc-N. Spectres IR et RMN

Rhenium(V) and technetium(V) complexes with N-[2(1H-pyrolylmethyl)]-N'-(4-pentene-3-one-2)ethane 1,2-diaminate (C12H16N3O, MRP 20). X-ray crystal structures of H3MRP 20 and TcO(MRP 20)

Synthesis of N-[2(1H-pyrolylmethyl)]-N′-(4-pentene-3-one-2)ethane-1, 2-diamine has been effected and the compound characterised by X-ray diffraction. Crystal data for C12H19N3O: space group P21/c: a=10.358(3), b=7.953(1), c=15.640(4) A, β=101.63(1)°, V=1261(2) A3 to give Z=4 for D=1.165 g cm−3. Structure solution and refinement based on 2114 reflections converged at R=0.064, Rw=0.079. Reaction of this molecule with Bu4N[TcO(ethylene glycolate)2] results in the formation of a neutral technetium(V) complex [TcOL]. The X-ray structure of this complex confirms a five-coordinate, square based pyramidal geometry with no crystallographic axes of symmetry. Crystal data: orthorhombic space group P212121; a=11.701(1), b=14.949(2), c=7.516(1) A, V=1314.6 A3 to give Z=4 for D=1.68 g cm−3. Structure resolution and refinement based on 2115 reflections converged at R=0.037, Rw=0.033. Reaction of N-[2(1H-pyrolylmethyl)]-N′-(4-pentene-3-one-2)ethane-1,2-diamine with rhenium(V) oxotrichlorobistriphenylphosphine [ReOCl3(PPh3)2] or a rhenium(V) glycolato precursor yields the [ReOL] complex. The compounds have been studied by NMR, UVVis, IR spectroscopy as well as by mass spectrometry. The obtained results have been discussed in terms of the complex formation and the different transition metals.

Synthesis, characterization and x-ray molecular and crystal structure of Tc(NS)Cl3(Me2PhP)(Me2PhPO)-a first example of mixed phosphine/phosphine oxide coordination

The reaction of TcNCl 2 (Me 2 PhP) 3 with excess S 2 Cl 2 yields trichloro(dimethylphenylphosphine)- (dimethylphenylphosphine oxide)thionitrosyltechnetium(II), Tc(NS)Cl 3 (Me 2 PhP)(Me 2 PhPO), whereas an equimolar reaction mixture yields dichlorotris (dimethylphenylphosphine)thionitrosyltechnetium- (I), Tc(NS)Cl 2 (Me 2 PhP) 3 . Tc(NS)Cl 3 (Me 2 PhP)(Me 2 PhPO) (formula weight 543.74) crystallizes in the orthorhombic space group P 2 1 2 1 2 1 with a = 10.513(1), b =14.274(2) and c =15.187(2) A ( Z = 4). The phosphine oxide ligand is arranged in trans position to the linearly coordinated thionitrosyl group.

Ligand exchange reactions between copper(II)- and nickel(II)-chelates of different sulfur- and selenium-containing ligands. VI [1]. Kinetics of ligands exchange reactions studied by stopped-flow ESR

Abstract The kinetics of ligand exchange reactions studied by means of stopped-flow ESR measurements are reported. The concentrations-time curves recorded for all reactions investigated correspond ton simple second-order rate laws. The rate constants of the reactions between copper(II) dithiolenes and Cu(Et 2 dsc) 2 (Et 2 dsc = diethyldiselenocarbamate) or Ni(Et 2 -dsc) 2 were found to be: [Cu(mnt) 2 ] 2– (mnt = maleo-nitriledithiolate) + Cu(Et 2 dsc) 2 , k 2 = (2.3 ±0.3)· 10 2 1 mol −1 s −1 ; [Cu(mnt) 2 ] 2− + Ni(Et 2 dsc) 2 , k 2 = (2.1 ± 0.1)· 10 2 1 mol −1 s −1 and [Cu(dmit) 2 ] 2− (dmit = isotrithione-3.4-dithiolate) + Ni(Et 2 dsc) 2 , k 2 = (2.5 ± 0.3)· 10 2 1 mol −1 s −1 . A rate constant of k 2 = (2.0 ± 0.3)· 10. 2 1 mol −1 s −1 was determined for the reaction between (Cu(Et 2 dsc) 2 and Cu(Et 2 -dtc) 2 (Et 2 dtc = diethyldithiocarbamate). Additional experiments suggest a chain mechanism for the ligand exchange reactions in which the mono-chelates e.g. [Cu(mnt)] s react as active sites.

Mixed-ligand complexes of technetium Part XI. Nitridotechnetium complexes with tri- and tetradentate azomethines. X-ray molecular and crystal structure of [N-(2-ethoxycarbonyl-3-oxo-but-1-en(1)yl)-2-aminophenolato](triphenylphosphine)nitridotechnetium(V), TcN(ecbap)(Ph3P)

Diamagnetic nitridotechnetium(V) complexes with tri- and tetradentate azomethine ligands which possess electron withdrawing groups in their periphery can be prepared starting from TcNCl 2 (Ph 3 P) 2 or (in the case of the tetradentate ligands) TcNX 4 − (X = Cl, Br). The products are air stable compounds which have been characterized by elemental analysis, infrared and UV-Vis spectroscopy, NMR and mass spectrometry. The mixed-ligand complex [ N -(2-Ethoxycarbonyl-3-oxo-but-l-en(1)yl)-2-aminophen- olato](triphenylphosphine)nitridotechnetium(V) (C 31 H 28 N 2 O 4 PTc, M r = 622.5) crystallizes monoclinic in the space group C 2/ c . The coordination geometry is a distorted square pyramid with the nitrido ligand at the apex.

Direct fission versus sequential evaporation mechanism of sputtered caesium iodide cluster ions

A triple stage hybrid mass spectrometer was scanned for the trapping of the reaction intermediates of the over-all loss of two CsI-moieties from size-selected caesium iodide cluster ions of the general formula Cs (CsI)+n. In addition to appropriate MS/MS/MS-methods an electrically floated collision cell has been applied to trap intermediates of unimolecular and collision-induced evaporations. In comparison with other experimental findings the features of the evaporation mechanism are discussed.

Redoxreaktionen an nickelorganokomplexen durch nitrosoverbindungen und aliphatische aldehyde: Möglichkeiten des einsatzes der spintrapmethode

Abstract ESR investigations of the reaction between (bipy)Ni(C 2 H 5 ) 2 and aromatic nitroso compounds (RNO) show the formation of paramagnetic, unstable complexes containing the radical RNO . which is followed by elimination of nitroxide radicals C 2 H 5 (R)NO . . (bipy)Ni(COD) is oxidized by RNO to give nickel(I) species and several trapped radicals derived from COD. In the presence of aldehydes no paramagnetic nickel species, but ethyl radicals and spin adducts of the aldehydes can be observed. The mechanism of the reaction is discussed.

Synthesis, Characterization and Crystal Structure of {N-(2-Mercaptoacetyl)-N′-[4-(pentene-3-one-2)]ethane-1,2-diaminato } oxotechnetium(V)

{ N-(2-Mercaptoacetyl)-N′-[4-(pentene-3-one-2)]ethane-1,2-diaminato} oxotechnetium(V) has been prepared by the reaction of (Bu4N)TcOX4 complexes (X = Cl, Br) with N-(mercaptoacetyl)-N′-[4-(pentene-3-one-2)]ethane-1,2-diamine in methanolic solution. The compound forms dark red crystals which were characterized by elemental analysis, IR and 1H NMR spectroscopy, mass spectrometry, as well as an X-ray structure determination. The compound crystallizes triclinic in the centrosymmetric space group PĪ with a = 776.50(3), b = 819.69(6), c = 1040.43(7) pm, α = 92.944(6)°, β = 110.805(5)° and γ = 109.957(5)°. The final R value is 0.023. In the monomeric complex the five coordinate technetium atom exhibits a square pyramidal environment with the donors of the tetradentate ligand in the basal plane and the oxo ligand in the apical position. The bond length Tc–O = 165.7(2) is within the normal range of Tc=O double bonds.