Lenzi Kaden

Nitrido complexes of technetium with tertiary phosphines and arsines

Abstract Diamagnetic Technetium(V) complexes of general formulae [TcNX 2 (Ph 3 Y) 2 ] and [TcNX 3 (Me 2 PhP) 3 ] (X = Cl, Br; Y = P, As) were prepared starting from TcNCl 4 − and TcNBr 4 − , respectively and were characterized. Ligand exchange rates with diethyldithiocarbamate, et 2 dtc − and N-(N″-morpholinylthiocarbonyl)benzamidinate, morphtcb − , were determined.

Tc(NX)Y3(Me2PhP)2 complexes (X = O or S; Y = Cl or Br). Preparation, characterization and EPR studies

Abstract The d 5 -‘low-spin’ Tc(II) complexes tribromonitrosyl-bis(dimethylphenylphosphine)technetium(II) and tribromo-thionitrosyl-bis(dimethylphenylphosphine)technetium(II) were prepared by ligand exchange starting from the analogous chloro compounds. The complexes were characterized chemically and IR, UVVis and EPR spectroscopically. In the room temperature EPR spectra a well-resolved 99 Tc hyperfine splitting is observed inidicating a ground state of the unpaired electron which is well separated from the other orbit states. The general features of the spectra at low temperatures are characteristic for an axially symmetric spin Hamiltonian. Analysis of the 99 Tc and 31 P hfs (hfs = hyperfine splittings) shows a marked covalency of the Tcligand bonds. A comparison is given between the chloro and bromo, as well as between the nitrosyl and thionitrosyl complexes.

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.

HTc(N2)(dppe)2 as starting material for mixed-ligand complexes of technetium(I)

Abstract In the complex HTc(N2)(dppe)2 the nitrogen ligand is most labile and can be exchanged under mild conditions for CO, isonitriles and phosphites (L1), yielding neutral hydridocomplexes of Tc(1) HTcL1(dppe)2. HTc(CO)(dppe)2 is also formed from the title compound by CO abstraction from methanol. In the complexes HTcL1(dppe)2 the hydrido ligand can be exchanged for acetonitrile (L2), yielding cationic mixed-ligand complexes of Tc(I) TcL1L2(dppe)2+, which are isolated as hexafluorophosphates.

Mixed-ligand complexes of technetium-III. Synthesis and characterization of [bis(diphenylphosphino)ethane]tetrakis(trimethylphosphite)technetium(I) hexafluorophosphate, [Tc(DPPE)(TMP)4]PF6

Abstract The diamagnetic technetium(I) complex [Tc(DPPE)(TMP)4]PF6 was prepared from [Tc(N2)H(DPPE)2] and characterized by elemental analysis, 1H- and 99Tc-NMR spectroscopy and fast atom bombardment mass spectrometry. [Tc(DPPE)(TMP)4]PF6 is a prototype compound for technetium complexes with mixed phosphine-phosphite coordination spheres.

Mixed-ligand complexes of technetium XIII. A new and facile synthesis, structure and electrochemical behaviour of trans-[Tc(dppe)2(butNC)2](PF6)· ethanol (dppe = bis(diphenylphosphino)ethane, butNC= tert-butylisocyanide)☆

The Tc(I) mixed-ligand complex, trans-[Tc(dppe)2(butNC)2](PF6) (dppe=bis(diphenylphosphino)ethane, butNC=tert-butyl-isocyanide) has been prepared from [Tc(tu−S)63+ (tu-S=thiourea) and a mixture of both ligands. The compound crystallizes triclinic in the space group P1 (a=9.999(5), b=12.059(5), c=13.776(7) A, α=113.55(2), β=92.18(3), γ=101.50(3)°, Z=1). The technetium atom has a slightly distorted octahedral coordination sphere with the isocyanide ligands in trans-position to each other. By cyclic voltammetry, at a Pt electrode, trans-[Tc(dppe)2(butNC)2](PF6) undergoes a single electron reversible oxidation at E12ox=0.91 V versus SCE.

Redox Properties and Ligand Effects for the Hydrido-Technetium-Dinitrogen, -Carbonyl and -Isocyanide Complexes trans-[TcH(L)(Ph2PCH2CH2PPh2)2] (L = N2, CO or CNR)

The redox properties of trans-[TcH(Li(dppe)2] ( L = CO, N2, CNBut or CNC6H11; dppe = Ph2PCH2CH2PPh2 ) have been studied by cyclic voltammetry and controlled potential electrolysis at a Pt electrode in 0.2 M [BU4N][BF4] / THF. They undergo a single-electron quasi-reversible or irreversible anodic process at an oxidation potential which relates linearly with that exhibited by the corresponding rhenium complexes trans-[ReCl(L)(dppe)2]. The electron-richness ( Es ) and polarisability ( β ) parameters have been obtained for the {TcH(dppe)2} centre (0.34 V vs. SCE and 4.0, respectively), whereas the isocyanide ligands appear to present PL values ca. 0.3 V above those exhibited at {Cr(CO)5}. A correction for the “ normal ” EL values is also suggested for these ligands at the Tc site.