Luciano Magon

Complexes of technetium(IV) and (III) with tertiary phosphines

Abstract The synthesis and characterization of the complexes trans-TcX4L2 and mer-TcX3L3 (X = Cl and Br, and L = PMe2Ph, PEt2Ph and PPh3) are reported. Configurations were deduced by far-IR and 1H NMR studies. Magnetic susceptibility and 1H NMR results for mer-TcCl3(PMe2Ph)3 are compared with those for analogues d4 complexes.

Reactivity of the [ReNR]3+ and [ReN]2+ cores toward bis(diphenylphosphino)amine and its derivatives. Synthesis and crystal structures

The complexes fac-[Re(NMe)Cl3{NH(PPh2)2-P,P′}]1, [ReNCl{NH(PPh2)2-P,P′}2]X (X = Cl 2 or BPh42a), [Re(NMe) Cl2{N(XPPh2)2-X,X′}(PPh3)](X = 0 3, S 4 or Se 8), [Re(NMe)Cl{N(XPPh2)2-X,X′}2](X = S 5 or Se 9), [ReNCl{N(SPPh2)2-S,S′}(PPh3)]6, [ReN{N(XPPh2)2-X,X′)2](X = S 7 or Se 10) and trans-[ReOCl2{N(OPPh2)2-O,O′}(AsPh3)]11 were obtained by treatment of [Re(NMe)Cl3(PPh3)2], [ReNCl2(PPh3)2] or [ReOCl3(AsPh3)2] with the appropriate ligand under different experimental conditions. The structures of complexes 1, 2a and 6 were determined by X-ray crystallography. In 1 and 2a the Re atom is six-co-ordinate in a distorted octahedral configuration, whereas in 6 the Re atom is five-co-ordinate square pyramidal with the N atom in the apical position.

Reactivity of oxotetrachlororhenate(V) with bidentate and tetradentate schiff bases containing oxygen and nitrogen donors

Abstract The five-coordinated rhenium(V) [(C 6 H 5 ) 4 As][ReOCl 4 ] compound reacts with bidentate and tetradentate Schiff bases containing oxygen and nitrogen donors to give six-coordinated complexes. With the ligands (LH) (L = N-methylsalicylidene-iminate, N-phenylsalicylideneiminate, half N, N′-ethylenebis(salicylideneiminate) and 8-hydroxyquinolinate), the complexes [(C 6 H 5 ) 4 As][ReOCl 4 (LH)], [(C 6 H 5 ) 4 As][ReOCl 3 (L)] or ReOCl(L) 2 are obtained. The complexes were characterized by elemental analysis and conductivity measurements. Their stereochemistries were postulated on the basis of infrared spectra and X-ray data previously reported for analogous oxo-rhenium(V) compounds.

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.

Technetium(V)–nitrido complexes of dithiocarbazic acid derivatives. Reactivity of [TcN]2+ core towards Schiff bases derived from S-methyl dithiocarbazate. Crystal structures of [S-methyl 3-(2-hydroxyphenylmethylene)dithiocarbazato]nitrido(triphenylphosphine)technetium(V) and bis(S-methyl 3-isopropylidenedithiocarbazato)nitridotechnetium(V)

New technetium(V)–nitrido complexes with bi- and tri-dentate Schiff bases, derived from the condensation of various aldehydes and acetone with the methyl ester of dithiocarbazic acid, NH2NHC(S)SCH3, were prepared by substitution or substitution–reduction reactions on the square-pyramidal complexes [TcVNCl2(PPh3)2] and [TcVINCl4]–. The final complexes all maintain the square-pyramidal geometry of the starting compounds with the TcN group in an apical position. The bidentate ligands give rise to mono- and di-substituted complexes, in which they are co-ordinated to the metal through the β-nitrogen atom and the thiol sulphur atom; in monosubstituted complexes, the remaining two positions in the plane of the square pyramid are occupied by triphenylphosphine (PPh3) and Cl– groups. The tridentate Schiff bases co-ordinate to the metal, in the basal plane, as doubly negatively charged ligands through the phenolic oxygen atom, the β-nitrogen atom, and the thiol sulphur atom, the fourth position being occupied by the phosphorus atom of a PPh3 group. The crystal structures of [TcNL1(PPh3)](1)[H2L1=S-methyl 3-(2-hydroxyphenylmethylene)dithiocarbazate] and [TcN(L12)2](2)(HL12=S-methyl 3-isopropylidenedithiocarbazate) have been determined. Relevant crystal data for (1) are: refined from 5 008 reflections with I 3σ(I) to a final R of 0.029, crystals are triclinic, space group P, with unit-cell dimensions a= 8.309(1), b= 12.294(1), c= 13.308(3)A, α= 96.22(1), β= 95.07(1), γ= 101.34(1), and Z= 2; for (2): refined from 1 756 reflections with I 3σ(I) to a final R of 0.023, crystals are monoclinic, space group I2/a, with unit-cell dimensions a= 16.707(3), b= 8.838(1), c= 12.514(2)A, β= 106.85(1)°, and Z= 4. In both complexes, the co-ordination around Tc is distorted square pyramidal with an apical multiply bonded nitrogen atom [TcN 1.611(3)A in (1) and 1.613(3)A in (2)] and the basal ligands bent away from the nitrido group.

Reactivity of rhenium(V) complexes containing different cores such as [ReO]3+, [ReNR]3+ and [ReN]2+ toward bis(diphenylphosphino)methane: synthesis and crystal structures

The complexes fac-[ReOCl3(dppm-P,P′)] (1a), mer-[ReOCl3(dppm-P,P′)] (1b), mer-[ReCl3(dppm-P,P′)(dppom-P)] (2), [ReCl4(dppom-P,O)] (3) and mer-[ReCl3(dppm-P,P′)PPh3] (4) (dppmPh2PCH2PPh2, dppomPh2PCH2P(O)Ph2) were obtained by reaction of [ReOCl3(PPh3)2] or [AsPh4][ReOCl4] and dppm under different experimental conditions. Complex 1b is probably obtained via the intermediate formation of complexes 2 or 4. The complexes fac-[Re(NCH3)Cl3(dppm-P,P′] (5), trans-[ReNCl2(dppm-P)PPh3] (6) and [ReNCl(dppm-P,P′)2]Cl (7) were also obtained starting from [Re(NCH3)Cl3(PPh3)2] and [ReNCl2(PPh3)2], respectively. The structures of 1a and 3 were determined by X-ray crystallography. Compound 1a is monoclinic, space group P21/c, with a=11.156(4), b=17.264(5), c=14.467(5) A and β=110.96(3)°. The molecular complex is distorted octahedral. Selected bond distances (A) are: ReO(oxide) 1.671(6), ReCl(trans to O) 2.452(3), ReCl(trans to P) 2.365(4) and 2.373(3), ReP 2.439(3) and 2.449(2). The PReP chelation angle is 69.2(1)°. Compound 3 is orthorhombic, space group Pccn, with a=34.843(5), b=8.242(2) and c=19.342(4) A. The molecular complex is roughly octahedral with the oxidized dppm ligand chelated through the P atom and the O atom of the PO group. Selected bond distances (A) are: ReCl(trans one other) 2.355 (mean), ReCl(trans to P) 2.353(3), ReCl(trans to O) 2.215(5), ReO 2.087(7). The PReO chelation angle is 80.7(2)°.

Relative stabilities of complexes of MO22+ (M = U, Np, and Pu) with monocarboxylate anions

Abstract Stability data for complexes of yl(VI) ions MO 2 2+ (M = U, Np, and Pu) with monocarboxylic ligands L are reported and discussed (L = CH 3 CO 2 − , C 2 H 5 CO 2 − , and CH 2 ClCH 2 CO 2 − ). Stability constants refer to the formation equilibria of complexes in aqueous NaClO 4 solution at 20° and 1 M ionic strenght. In the range of ligand concentrations examined, complexes are formed in which the highest average ligand number, n is three. The stability order of complexes of the various ligands examined is UO 2 2+ >NpO 2 2+ >PuO 2 2+ . The stabilities of complexes of a given MO 2 2+ ion increase with increasing ligand basicity, which suggests a strong hard character for these oxycations.

Synthesis and characterization of new formamidino and triazenidocomplexes of rhenium(I): [Re(CO)2(PPh3)2(ArNxxxXxxxNAr)] (X = CH,N)

Abstract [Re(CO) 3 (PPh 3 ) 2 Cl] reacts with Li(ArNxxxXxxxNAr) (X = CH, N; Ar = p -CH 3 C 6 H 4 , C 6 H 5 , p -ClC 6 H 4 , p -FC 6 H 4 in boiling THF to yiled[[Re(CO) 2 (PPh 3 ) 2 - (ArNxxxXxxxNAr)]. The structure of these new complexes and the mode of coordination of the organonitrogen ligand are discussed on the basis of i.r. and 1 H n.m.r spectra

Thermodynamic properties of actinide complexes. Part. III. Uranyl(VI)-glycolate system

Abstract The changes in free energy, enthalpy and entropy for the formation of uranyl(VI)-glycolate complexes, have been determined at 25 °C and in aqueous perchlorate medium 1.00 M. All three complexes formed, are found to be stabilized by entropy, while the enthalpy term, excepting the third step, opposes the complex formation. The data are in agreement with the presence of chelate structures in a decreasing measure for each of the three successive steps of complexation.

Metal complexes containing ‘inorganic (carbon-free) chelate rings.’ Reactivity of the [ReO]3+ core toward bis(diphenyl-phosphino)amine derivatives. Crystal structures of [ReOCl2{N(XPPh2)2}(PPh3)](X = O or S) and [ReO(OEt)-{N(SPPh2)2}2]

The complexes [ReOCl3(PPh3)2] and [ReOCl2(OEt)(PPh3)2] react with an excess of NH(OPPh2)2 to give [ReOCl2{N(OPPh2)2}(PPh3)]1. When the donor atoms are changed by using NH(SPPh2)2 as the ligand the mono- and di-substituted complexes [ReOCl2{N(SPPh2)2}(PPh3)]2 and [ReOCl-{N(SPPh2)2}2]3a are obtained. Complex 3a can also be prepared by using the anionic compound [ReOCl4]– as the starting material. When complex 3a is crystallized from CH2Cl2–EtOH, [ReO(OEt){N(SPPh2)2}2]3b is obtained. The structures of complexes 1,2 and 3b were determined by X-ray crystallography. Compound 1 is triclinic, space group P, with a= 14.885(5), b= 13.815(5), c= 10.019(5)A, α= 92.35(3), β= 108.46(3), γ= 99.10(3)° and Z= 2. The structure was refined to R= 0.028, based on 4204 observed reflections. Compound (2) is triclinic, space group P, with a= 16.831(5), b= 14.667(5), c= 9.918(5)A, α= 99.48(3), β= 104.93(3), γ= 92.57(3)° and Z= 2. The structure was refined to R= 0.038, based on 5955 observed reflections. Compound 3b is trinclinic, space group P, with a= 10.214(5), b= 10.750(5), c= 13.947(4)A, α= 111.72(3), β= 113.07(3), γ= 64.06(3)° and Z= 1. The structure was refined to R= 0.063, based on 4062 observed reflections. All three compounds show slightly distorted octahedral geometries. The chlorine atoms are trans in 1 and cis in 2. The Re–O(oxide) bonds show some triple bond character, and exert a strong trans influence.