Ralph Maier

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.

Molecular structure and charge distribution in organometallics of the 4f and 5f elements V: crystal and molecular structure of tetrakis(ν5-cyclopentadienyl)-thorium(IV) and the temperature dependence of its electrical dipole moment☆

The crystal and molecular structure of Th(C5H5)4, was investigated by single crystal X-ray diffraction. The compound crystallizes tetragonal with a = 868.3(1), c = 1064.4(3) pm with two molecules per unit cell. The average Th—Cp distance of 260.6 pm is in good agreement with the predicted distance of 258.8 pm, and is larger than the corresponding distance of the uranium compound (253.8 pm). The temperature dependence of the dipole moment of the title compound, of thorium tetramethylcyclopentadienide (Cp′,Th), and of the homologous uranium compound in benzene solution is discussed with respect to their molecular structure.

Chloro-lanthanide, and plutonium complexes containing the hydrotris (3,5-dimethylpyrazol-1-yl)borate ligand: the crystal and molecular structures of [PrCl (μ-Cl)TpMe2 (3,5-Me2pzH)]2 and YbCl2TpMe2 (THF)

Abstract Reactions of PuCl3 and LnCl3 (Ln=Pr, Nd ) with the stoichiometric amount of KTpMe2 (TpMe2=HB (3,5-Me2pz)3) yielded the dimeric [MCl (μ-Cl)TpMe2 (Me2pzH)]2 compounds (M=Pu (1), Pr (2), Nd (3)). The analogous reaction with YbCl3 afforded the monomeric YbCl2TpMe2 (THF) complex (4). The crystal and molecular structures of 2 and 4 have been assessed by means of single crystal X-ray diffraction analysis. In 2 each Pr atom is seven-coordinate and is linked to the adjacent metal centre by two bridging chlorine ligands. In 4 the Yb atom is six-coordinate and displays octahedral geometry. 4 undergoes intermolecular rearrangement reactions to yield [YbCl2TPMe2 (Me2pzH)]·THF (6) and [YbCl3TpMe2]− [ (Me2pzH2)]+ (7). The molecular structures of 6 and 7 were determined by X-ray diffraction. In 6 the tridentate ligand, the two chlorine atoms and the nitrogen atom of the neutral dimethylpyrazole describe a distorted octahedron. 7 consist of discrete [YbCl3TpMe2]− and [ (Me2pzH2)]+ ions, with the ytterbium atom of the cation coordinated to three pyrazolyl nitrogens and three chlorine atoms.

Molekülstruktur und ladungsverteilung der 4f- und 5f-elemente: III. Dipolmomente und Ladungsverteilung der 1 : 1-Addukte der Tris(cyclopentadienyl)lanthanoide(III) bzw.-actinoide(III) mit Tetrahydrofuran; Röntgenstrukturanalyse von (C5H5)3Dy · THF☆

Abstract The dielectricity constant and the dipole moment of the 1 : 1 adducts of the tris(cyclopentadienyl)compounds of the trivalent lanthanoids La to Lu (with exception of the Pm compound) and of the lighter actinoids Th, U, Np, and Pu with tetrahydrofuran, (C5H5)3MIII. THF, were measured and the charge distribution within the molecule was investigated. From the partial electric moment for the metaloxygen bond, the distribution of the 4f- and 5f-electrons to the total electric dipole moment of the molecule was calculated. The crystal and molecular structure of the (C5H5)3Dy·THF was elucidated by single crystal X-ray investigation. The tetrad effect in the compound class (C5H5)3MIII·THF is discussed.

Metallorganische Chemie des Technetiums: X. Synthese, Charakterisierung und Röntgenstrukturanalyse von μ-Distickstoff-bis[hydrotris(3,5-dimethylpyrazolyl)-borato-technetium-dicarbonyl], [L★Tc(CO)2]2(μ-N2)☆

Abstract The compound [HB(3,5-Me2C3N2)3]Tc(CO)3 reacts after UV irradiation in THF with elementary nitrogen to give the air-stable N2-bridged binuclear complex {[HB(3,5-Me2C3N2)3]Tc(CO)2}2(μ-N2). The crystal and molecular structure of this first N2-bridged organometallic technetium complex has been determined by a single-crystal X-ray diffraction study. The compound crystallizes monoclinic (space group C2/c) with cell parameters a 2032.2(6), b 1454.7(4) and c 1427.0(5) pm and Z = 4. The NN distance is 116.0 pm and the TcNN angle is 174.0°. The IR, 1H NMR, UV and EI-MS spectroscopic data are discussed.

Molecular structure and charge distribution in organometallics of the 4f and 5f elements I: Dipole moment and charge distribution of the actinoid(IV) tetracyclopentadienides, An(C5H5)4

Abstract The dipole moments of the tetracyclopentadienides, Au(C5H5)4, of the lighter actinoids thorium, uranium and neptunium were measured in benzene solution. Although the compounds in the solid state have a quasi-Td molecular symmetry their dipole moments are not zero, owing to lowering of the molecular symmetry. The origin of the non-zero dipole moments is discussed.

Molekülstruktur und ladungsverteilung in metallorganischen verbindungen der 4f- und 5f-Elemente: II. Dielektrische untersuchungen an metallorganischen komplexen der 4f- und Übergangselemente mit C3v-und D3h-Molekülsymmetrie

Abstract The electric dipole moments of Pr[N(SiMe 3 ) 2 ] 3 ·.OC 4 H 8 and Cp 3 Pr·.NCC 2 H 5 with a quasi- C 3 v molecular symmetry and of Sc[N(SiMe 3 ) 2 ] 3 , Cl 3 In·2N(C 2 H 5 )3, and CP 3 La·2NCC 2 H 5 with D 3 h molecular symmetry were measured in benzene solutions. As expected, the compounds with D 3 h symmetry do not exhibit a dipole moment, while the compounds with C 3 v symmetry show a dipole moment higher than 4 D. The experimental values are in excellent agreement with the values calculated from crystallographic data. The possibility for accurate predictions about distances and angles in homologous compounds with unsolved crystal structure is discussed.

Bis(cyclopentadienyl)technetium(III)chlorid und Tris(cyclopentadienyl)technetium(III), neue metallorganische Verbindungen des dreiwertigen Technetiums

Abstract Technetium tetrachloride reacts with potassium cyclopentadienide in tetrahydrofuran to give the diamagnetic, air-stable (C 5 H 5 ) 2 TcCl ( 1 ). Single crystal X-ray diffraction analysis shows a short ring-metal distance of 187.7(5) pm, which is comparable with the corresponding distance in nickelocene, indicating high covalency. Reaction of the compound with KC 5 H 5 gives the red (C 5 H 5 ) 3 Tc ( 4 ), in which one cyclopentadienyl ring is σ-bonded. Mass spectroscopic investigations of the latter compound give evidence for the existence of (C 5 H 5 ) 4 Tc. The reactivity of (C 5 H 5 ) 2 TcCl is discussed.

Bis(cyclopentadienyl)rhenium(III)chlorid : Kristallstruktur, Eigenschaften und Reaktivität ; Darstellung und Charakterisierung von Cp3Re und Cp2ReH

Abstract Biscyclopentadienyl rhenium(III) monochloride, Cp2ReCl (1), was prepared by the reaction of rhenium pentachloride with potassium cyclopentadienide (1:4) in tetrahydrofuran. The crystal structure of 1 has been solved by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P21/c with cell parameters a = 582.8(1), b = 1251.2(2), c = 1306.6 (4) pm, and β = 107.24 (2)°; pcalc=2.568 Mg/m3 for Z = 4. The properties of 1 are discussed in comparison to the homologous compounds of trivalent vanadium and technetium. The synthesis and the properties of the hydride Cp2ReH (2) and of the tricyclopentadienyl rhenium, Cp3Re (3) are also discussed.

Metallorganische Chemie des Technetiums: VII. Röntgenstrukturanalyse von Tris(cyclopentadienyl)technetium(III), (η5-C5H5)2Tc(η1-C5H5); Dipolmomente und Ladungsverteilung der Spezies (C5H5)3 (M V, Tc, Re)

The crystal structure of the diamagnetic tris(cyclopentadienyl)technetium(III) (1) has been solved by single crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Pna21 with cell parameters a 1147.7(1), b 904.2(2), and c 1147.2(4) ppm; ϱcalc 1.636 Mg/m3 for Z  4. Two rings are π-bonded and the third one is σ-bonded. The charge distribution in the molecule and the effective electric charge of the σ-bonded carbon atom are discussed in comparison to the homologous compounds of vanadium and rhenium.