Noémia Marques

Metallorganische Chemie des Technetiums: VIII. Technetium(I)-carbonyl-Komplexe mit Polypyrazol-1-yl-borato-Liganden im Vergleich mit seinen Mn- und Re-Homologen

Abstract The compounds HB(C3H3N2)3Tc(CO)3 and HB(3,5-Me2C3HN2)3Tc(CO)3 have been synthesized for the first time, and their molecular and crystal structure as well as the structures of the known analogous compounds of manganese and rhenium determined by single-crystal X-ray diffraction. The IR-, 1H-NMR-, 13C-NMR-, UV- and EI-MS-spectroscopic data are discussed in correlation to the electric dipole moment and the charge distribution within the molecule.

Dihydrobis(3,5-dimethylpyrazolyl)borate derivatives of ƒ elements

Abstract The trivalent chlorides of U, Ce, Sm and Yb react readily in THF with KH2B(3,5-Me2Pz)2 to yield the complexes M[H(μ-H)B(3,5-Me2Pz)2]3. The crystal and molecular structures of U[H(μ-H)B(3,5-Me2Pz)2]3 and Sm[H(μ-H)B(3,5-Me2Pz)2]3 have been determined. The compounds are isomorphous with the six nitrogen donor atoms of the bis-chelating ligands arranged in a trigonal prismatic geometry. Each of the three rectangular faces of the trigonal prism is capped by a bridging BH … M three centre bond, leading to compounds where the metal centres are formally nine-coordinate. The synthesis and characterization of the related UIV derivatives UCl2[H2B(3,5-Me2Pz)2]2 and U(OBut)2[H2B(3,5-Me2Pz)2]2 are also reported. The crystal and molecular structure of {UCl[H(μ-H)B(3,5-Me2Pz)2[H(μ-O)B(3,5-Me2Pz)2]2}2, a dimeric complex formed during the recrystallization of UCl2[H2B(3,5-Me2Pz)2]2, is also presented. Each uranium centre is eight-coordinate and displays square antiprismatic geometry, distorted towards the dodecahedron.

Actinide poly(pyrazol-1-yl)borate complexes: synthesis and structure of hydrotris(3,5-dimethylpyrazol-1-yl)boratotrichlorotetrahydrofuran actinide(IV), M[HB(3,5-Me2Pz)3]Cl3(THF) (M=Th and U)

Abstract The reaction of MCl4 with K[HB(3,5-Me2Pz)3] in THF gives the monosubstituted derivatives M[HB(3,5-Me2Pz)3]Cl3(THF) (M=Th (1) and U (2)) in excellent yields. The NMR spectra of the molecules indicate symmetrical structures with equivalent pyrazolyl groups. This has been corroborated by single-crystal X-ray analysis. The uranium center in 2 is seven-coordinate and displays capped octahedral geometry. The tridentate pyrazolylborate moiety and the three Cl atoms define the two staggered triangular faces respectively, the latter is capped by the THF oxygen. The coordination geometry is close to C3v symmetry. The steric congestion imposed by the bulky pyrazolylborate ligand is evidenced by the relative low coordination number and the long U—O bond length, 2.546(4) A. Crystal data 2: monoclinic, P21/n, a=10.195(2), b=14.905(2), c=17.414(4) A, β=100.08(2)°, V= 2605.32 A3 and Z=4. Complex 1 is isomorphous with 2.

Synthesis, characterization and reactivity of lantahnide(II) poly(pyrazol-1-yl)borates (LnSm, Eu and Yb); fluorescence studies of [EuL2(THF)2] [LB(pz)4, HB(pz)3]; X-ray crystal structures of [Eu{B(pz)4}2(THF)2] and ]Yb{B(pz)4}3]·(2H5OH

Abstract The reaction [LnI2(THF)x] (Ln - Sm, Eu, Yb) with 2 equiv. of K[B(pz)4] (pz = pyrazolyl) in THF resulted in the formation of [Ln{B(pz)4}2(THF)2] complexes. The molecular structure of [Eu{B(pz)4}2(THF)2] has been determined by single-crystal X-ray diffraction analysis. The [Sm{B(pz)4}2(THF)2] and [Yb{B(pz)4}2(THF)2] complexes are fluxional in solution, as indicated by the equivalence of the pyrazolyl rings in the 1H NMR spectra at room temperature. A static spectrum could be obtained for the Sm compound at -68°C with a pattern that is in accordance with the geometry found for the Eu complex, in the solid state. The complexes [{LnHB(pz)3}2(THF)2] (Ln - Sm, Eu, Yb) have been prepared by the procedure used to synthesize the [Ln{B)pz)4}2(THF)2] complexes. The THF molecules can be replaced by 1,2-dimethoxyethane yielding the compounds [{LnHB(pz)3}2(DME)] (Ln = Sm, Yb. [Sm[B)pz)42(THF2] and [Yb{B)pz)4}2(THF)2] react readily with alkyl halides, alcohols or alkynes to yield LnIII complexes that disproportionate to the [Ln{B(pz)4}3] complexes. The crystal structure of the compound [Yb{B(pz)4}3]·C2H5OH obtained in the reaction of [Yb{B(pz)4}2(THF)2] with ethanol was determined by X-ray diffraction analysis. Fluorescence studies on the Eu compounds are also reported.

Some reactions of hydrotris(3,5-dimethylpyrazolyl)-borato trichloroactinides(IV), MCl3(HBL3)·THF (M ≡ ThIV, UIV; L ≡ 3,5-dimethylpyrazolyl, THF ≡ tetrahydrofuran)☆

Abstract The thorium(IV) and uranium(IV) compounds MCl2(Cp)(HBL3) (Cp ≡ η5-C5H5), MCl2[N(SiMe3)2](HBL3) and M(NPh2)3(HBL3) have been prepared from MCl3(HBL3)·THF. IR, near-IR-visible, 1H NMR and 11B NMR spectra are reported for these compounds.

Uranium poly(pyrazol-1-yl)borate complexes: X-ray crystal structures of UCl2Cp[HB(3,5-Me2Pz)3] and UCl3[HB(3,5-Me2Pz)3]

Abstract The crystal and molecular structures of UCl2Cp[HB(3,5-Me2Pz)3] (1) and UCl3[HB(3,5-Me2Pz)3] (2) have been determined by single crystal X-ray diffraction. Compound 1 crystallizes in space group P 1 , a = 10.770(1), b = 11.146(5), c = 11.820(4) A, α = 114.53(2), β = 91.70(2), γ = 107.45(2)°, V = 1211.77 A3, Z = 2; compound 2 crystallizes in space group P21/c, a = 8.173(1), b = 14.279(3), c 19.167(7) A, β = 100.17(2)°, V = 2201.71 A3, Z = 4. In both compounds the uranium centre is six-coordinate and displays octahedral geometry, close to Cs, symmetry for complex 1 and to C3v symmetry for complex 2. For compound 1 the average UCl, UN and UC(Cp) bond distances are 2.60(1), 2.51(2) and 2.74(1) A; for 2 the average UCl and UN bond distances are 2.56(1) and 2.43(1) A.

Samarium(III) compounds supported by the hydrotris(3,5-dimethyl-pyrazolyl)borate ligand: synthetic utility of the putative, reduction prone Sm(III)-hydrocarbyls, ‘(TpMe2)2SmR’

Abstract Addition of a stoichiometric amount of KR (R=CH2C6H4-o-NMe2, C6H4-o-CH2NMe2, CH2C6H5) to a solution of Sm(TpMe2)2Cl in toluene or THF led to the immediate formation of the insoluble, purple Sm(TpMe2)2 compound. However, when these reactions are carried out in the presence of protic substrates such as HOPh, HCp, HCCPh, HOC6H2-2,4,6-tBu3, HNPh2 and 3,5-Me2pzH, the corresponding Sm(TpMe2)2(Y) compounds (Y=OPh (1), CCPh (2), Cp (3), OC6H2-2,4,6-tBu3 (4), NPh2 (5), 3,5-Me2pz (6)) readily form and in good yields. The structures of 4–6 have been established by X-ray crystallography.

Tetramethylurea adducts of the tricyclopentadienyl lanthanide complexes

Abstract The tetramethylurea adducts of tricyclopentadienyl lanthanide(III) complexes, Cp3Ln·TMU (Ln = La, Ce, Nd, Sm, Eu and Yb, TMU = 1,1,3,3-tetramethylurea), have been isolated by addition of the stoichiometric amount of (CH3)2NCON(CH3)2 to Cp3Ln·THF, in hexane. The compounds were characterized by standard techniques and the molecular structures of Cp3Ce·TMU and Cp3Nd·TMU were determined by single crystal X-ray diffraction analysis. The two compounds are isomorphous. The metal centre is tetrahedrally coordinated.

Synthesis and characterization of thorium and uranium tetraphenylimidophosphinate complexes. Crystal and molecular structures of Th(tpip)4, U(tpip)4 and UCl(tpip)3

Abstract Tetra(tetraphenylimidophosphinato)thorium, Th(tpip)4 (1), was obtained from Th(NO3)4·4H2O and Ktpip in aqueous medium. The analogous uranium compound, U(tpip)4 (2), has been prepared by reacting UCl4 with Ktpip in a 1:4 stoichiometric ratio, either in THF or in aqueous solution. X-ray diffraction analysis showed that compounds 1 and 2 were isostructural. The metal center is eight-coordinate by way of four bidentate tetraphenylimidophosphinate ligands in a square antiprismatic configuration. UCl(tpip)3 (3) has been isolated from the reaction of uranium tetrachloride with 3 equiv. of Ktpip in aqueous solution. When this reaction was run in THF both compounds, U(tpip)4 and UCl(tpip)3, were obtained. The molecular structure of 3 has been determined by X-ray crystallography. The uranium atom is seven-coordinate in a pentagonal bipyramidal configuration. These compounds were also characterized by infrared and 1H and 31P NMR spectroscopies.

Alkoxide and aryloxide derivatives of actinide(IV) polypyrazolylborates. Part II. Uranium(IV) bis[hydrotris(pyrazol-1-yl)borate] complexes

Abstract The complexes U(HBpz 3 ) 2 (OR) x Cl 2− x (pz=pyrazol- 1-yl; x =1, 2; RBu t , Pr i , and C 6 H 2 -2,4,6- Me 3 ) have been prepared from the reaction of U(HBpz 3 ) 2 Cl 2 with sodium alkoxides and aryloxides in the ratio 1:1 and 1:2. The temperature dependence of the 1 H NMR of the complexes has been studied. Fluxional behaviour was observed for the poly(pyrazol-1-yl)borate ligands and the barrier to rotation about the U-B axis was estimated for the complexes U(HBpz 3 ) 2 (OBu t ) 2 (Δ G ‡=53 ± 4 kJ mol −1 and U(HBpz 3 ) 2 (OC 6 H 2 -2,4,6-Me 3 )Cl (Δ G ‡=39 ± 3 kJ mol −1 ). 1 H NMR studies also indicated restricted rotation about the UOR bonds in the complexes U(HBpz 3 ) 2 (OR)Cl (Δ G ‡=62 ± 5 kJ mol −1 and U(HBpz 3 ) 2 (OR) 2 (Δ G ‡=62 ± 4 kJ mol −1 with RC 6 H 2 -2,4,6-Me 3 .