Edoardo Roncari

Crystal structures of technetium compounds

A. B. C. D. E. F. Introduction .__ _......_._ _.._....._....._...._........_....._ _ 191 Remarks . . . . . . . . .._ _..~ ~._.. 193 Oxides, technetate, and pertechnetate compounds _ _ _ _ . . . _ _ _ _ _ _ _ _ . . _ _ _ _ _ . . 194 Halideandoxyhalidecompounds _____.______...___.______________.... 195 Polyhalide and polypseudohalide complexes . _ . _ _ . _ . . _ . _ . . . . . . . . _ _ _ . . . . . 197 Complexes _._..._ _ _ _ _ _ _ _ _ _...._._ _ _ _ _ _ __.._ _ ___ _._.._ _ _ ___... 199 (i) Complexes containing Ir-acceptor ligands _ . . . . . . . _ _ _ . . . . _ _ _ _ . . . . . _ _ _ 199 (ii) Complexes containing the TFO group . _ _ . . _ . . . . . . . . . . . . . . . . . . . . . . 208 (iii) Othercomplexes 211 G. Miscellaneous 215 H.Conclusions ___......___ .... 216 (i) General 216 (ii) Bondlengths 218 (iii) Summary 222 Acknowledgments 224 References 224

Pentane-2,4-dione complexes of technetium99

SummaryPentane-2,4-dionatotechnetium99 complexes of the type PPh4[TcX4(acac)], TcBr3(acac)PPh3, TcX2(acac)2, TcX2 (acac) (PPh3)2, TcX(acac)2 PPh3 and Tc(acac)3 (X=Cl or Br) have been prepared and characterized. Where possible, their configurations have been determined from elemental analyses, conductivity and magnetic susceptibility measurements, and by i.r. and u.v.-visible spectroscopy.

Voltammetric behaviour of technetium99 complexes with π-acceptor ligands in aprotic medium. III. Oxidation of technetium(I) complexes with phosphine and carbon monoxide ligands

The anodic behaviour of TcCl(CO)2(PMe2Ph)3 and TcCl(CO)3(PMe2Ph)2 complexes has been studied in acetonitrile solvent. Both the complex undergo an overall two-electron oxidation process with the formation of Tc(III) species; the electrode mechanism leading to their formation has been studied. In particular the [TcCl(CO)(MeCN)2(PMe2Ph)3][ClO4]2 compound has been isolated and characterized.

Voltammetric behaviour of technetium99 complexes with π-acceptor ligands in aprotic medium. II. Reduction of TcCl3(PMe2Ph)3 and of TcCl4(PMe2Ph)2

Abstract The electrode reduction of the technetium 99 phosphine complexes TcCl 3 (PMe 2 Ph) 3 and TcCl 4 (PMe 2 Ph) 2 has been studied in acetonitrile solvent by electroanalytical techniques. The electrode processes, as well as the involved chemical equilibria, have been studied. Technetium(II) and technetium(I) phosphine complexes have been obtained by reducing TcCl 3 (PMe 2 Ph) 3 at different potential values. The voltammetric behaviour of these compounds of technetium in low oxidation states has been also reported. TcCl 4 (PMe 2 Ph) 2 undergoes an one-electron reduction giving rise to TcCl 3 (PMe 2 Ph) 3 as the main product.

Reactions of pertechnetate anion with triphenylphosphine. Molecular structure (at –100 °C) of (1,1-dimethyl-3-oxobutyl)triphenylphosphonium pentachloro(triphenylphosphine)technetate(IV)

The reactions of the [TcO4]– anion with PPh3 in various concentrations of HCl are reported. [TcCl4(PPh3)2], [TcCl5(PPh3)]–, and [TcCl6]2– were obtained and the anionic complexes were isolated with cations such as [PPh3H]+, [AsPh4]+, or [Ph3PC(Me)2CH2COMe]+. The crystal structure of the title complex was determined at –100 °C from 1 761 independent reflections and refined to R= 0.065. Crystals are monoclinic, space group P21/n, a= 21.909(4), b= 18.963(4), c= 9.896(3)A, β= 103.05(5)°, and Z= 4. The structure consists of well separated units of octahedral [TcCl5(PPh3)]– anions, and tetrahedral phosphonium cations, in which the phenyl groups are in a ′ propeller ′ configuration around P. Selected bond distances and angles are Tc–Cl (mean) 2.34(1), Tc–P 2.57(1)A, Cl–Tc–Cl (mean) 90.7(4), Cl–Tc–P 88.7(4)°.

Voltammetric behaviour of technetium99 complexes with π-acceptor ligands in aprotic medium. I. oxidation of TcCl3(PMe2Ph)3

Abstract The use of the electroanalytical techniques to study the oxidation of the technetium(III) phosphine complex TcCl 3 (PMe 2 Ph) 3 in acetonitrile medium evidentiated the feasibility of the obtainement of two distinct oxidation products, TcCl 4 (PMe 2 Ph) 2 and [TcCl 2 (PMe 2 Ph) 3 (MeCN)] + ClO − 4 , depending on the nature of the supporting electrolyte. The latter compound has been also chemically prepared and characterized. Furthermore the formation, as primary electrode product, of a relatively long lived intermediate compound, [TcCl 3 (PMe 2 Ph) 3 ] + ClO − 4 , has been observed. The electrode oxidation processes have been also studied.

Voltammetric behaviour of rhenium(I) complexes with phosphine and carbon monoxide ligands in acetonitrile solvent

SummaryThe anodic and cathodic behaviour of the complexesmer-[ReCl(CO)3(PMe2Ph)2],fac[ReCl(CO)3(PMe2Ph)2],mer-[ReCl(CO)3(PPh3)2], and [ReCl(CO)2(PMe2Ph)3] in acetonitrile solvent were studied using platinum and mercury electrodes. Cyclic voltammetry and controlled potential coulometry were the main electroanalytical techniques employed. The nature of the electrolysis products and of the electrode oxidation and reduction processes were investigated. In particular, [ReCl(CO)(MeCN)2(PMe2Ph)3][ClO4]2, [ReCl3(CO)2(PMe2Ph)2], and a not completely defined rhenium(-I) complex were electrochemically synthesized and characterized by means of i.r. and1H n.m.r. spectroscopy, and by elemental analysis.

Reactivity of Schiff base rhenium(V) complexes with dimethylphenylphosphine

SummaryThe ReOX2L(PPh3) complexes (X = Cl or Br and L =N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N′-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate) react with dimethylphenylphosphine (PMe2Ph) to give ReOX2L(PMe2Ph) initially by displacement of the phosphine ligand and then the ReX2L(PMe2Ph)2 complexes with reduction of rhenium(V) to rhenium(III). The complexes were characterized by elemental analysis, magnetic susceptibility measurements and i.r. and1H n.m.r. spectra.

Electroanalytical study of the kinetics of thefac-mer isomerization of [ReCl(CO)3(PMe2Ph)2]+ in acetonitrile

SummaryThe isomerization offac-[ReCl(CO)3(PMe2Ph)2]+ to the corresponding meridional-trans isomer has been studied by electroanalytical techniques in MeCN solvent. Chronoamperometric and cyclic voltammetric data relative to the oxidation offac- andmer-[ReCl(CO)3(PMe2Ph)2] allow the accurate determination of the very high kinetic rate constant for the isomerization and permit discussion of thermodynamic aspects of redox homogeneous chemical reactions involving species of the different redox couples arising from the anodic processes.

Mixed schiff base, carbonyl(phosphine)rhenium(I) complexes

SummaryThe Re(CO)2(L)P2 complexes (L=N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N′-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate; P=dimethyl(phenyl)phosphine or triphenylphosphine) were synthesized from the ReCl(CO)3P2 complexes and characterized by elemental analysis, i.r. and1H n.m.r. spectroscopy.