Die Reaktion von Rheniumtrichlorid-dinitrosyl mit Triphenylphosphan Die Kristallstruktur von [ReCl3(NO)(NPPh3)(OPPh3)]

Reaction of Rhenium Trichloride Dinitrosyl with Triphenyl Phosphane. Crystal Structure of [ReCl₃(NO) (NPPh₃) (OPPh₃)] Triphenyl phosphane reacts with ReCl₃(NO)₂ in dichloro methane solution forming the phosphaneiminato complex [ReCl₃(NO)(NPPh₃)(OPPh₃)], which is characterized by it's i.r. spectrum and by ³¹P nuclear magnetic resonance. The crystal structure was determined by the aid of X-ray diffraction data (3 133 independent reflexions, R = 3.9%). The complex crystallizes monoclinic in the space group P2₁/n with four formula units per unit cell. The lattice dimensions are a = 1114, b = 1825, c = 1931 pm, β 96.6°. In the complex the rhenium atom has the coordination number six, the ligands being three chlorine atoms, the linear bonded Nitrosyl group, the O atom of the triphenyl phosphane oxide, which is coordinated trans to the NO ligand, and the N atom of the phosphaneiminato group. The ReN and PN bond lengths of the (NPPh₃)? ligand (186 and 163 pm, resp.) indicate double bond character; in contrast to other phosphaneiminato complexes of transition metals with linear array M?N?P, in [ReCl₃(NO)(NPPh₃)(OPPh₃)] the Re? N? P bond angle is only 139°.     

Darstellung und Kristallstruktur von Pb2(NO2)(NO3)(SeO3)

Crystals of Pb₂(NO₂)(NO₃)(SeO₃) were synthesized by partial reduction of nitrate ions with native copper under hydrothermal conditions. The crystal structure [a=5.529 (2) Å,b=10.357 (3) Å,c=6.811 (2) Å, space group Pmn2₁,Z=2] was determined from 1 707 independent X-ray data up to sin /=0.81 Å^–1 and was refined toR _w =0.028. The Pb(1) atom is ten coordinated to O atoms [Pb(1)-O from 2.51 Å to 2.96 Å], the Pb(2) atom has three nearest O atoms [Pb(2)-O=2.41 Å (1 ×) and 2.45 Å (2 ×)] and six next-nearest O atoms [Pb(2)-O from 2.80 Å to 3.22 Å].

Herrn Prof. Dr.K. Komarek zum 60. Geburtstag gewidmet.     

Kristallstrukturen von [TiF3(NPPh3)(HNPPh3)]2 und von HNPPh3

Crystal Structures of [TiF₃(NPPh₃)(HNPPh₃)]₂ and of HNPPh₃ The phosphoraneiminato-phosphaneimine complex [TiF₃(NPPh₃)(HNPPh₃)]₂ was obtained by the reaction of TiF₄ with Me₃SiNPPh₃ in boiling dichloromethane. It crystallizes from 1,2-dichloroethane as yellow crystals which include four molecules C₂H₄Cl₂ per dimeric formula unit. Space group P2₁/n, Z = 2, structure solution with 7270 independent reflections, R = 0.060 for reflections with I > 2σ(I). Lattice dimensions at ?50°C: a = 1417.5, b = 1896.9, c = 1586.6 pm, β = 101.22°. The compound forms centrosymmetric dimeric molecules via μ₂-F bridges with TiF distances of 194.6 and 223.3 pm, the longer one being in trans-position to the N atom of the (NPPh₃)^? ligand. Its TiN bond length of 177.7 pm corresponds with a double bond. The TiN bond length of the HNPPh₃ donor molecule of 213.4 pm is typical for a donor acceptor bond. According to the crystal structure determination the phosphaneimine HNPPh₃ forms monomeric molecules without intermolecular hydrogen bridges with a PN bond length of 152.4 pm. Space group P2₁/c, Z = 4, structure solution with 3229 independent reflections, R = 0.062 for reflections with I > 2σ(I). Lattice dimensions at ?70°C: a = 1460.4, b = 928.9, c = 1096.6 pm, β = 93.35°.     

Zur Kenntnis von Ag6(SO4)(SiO4)

About Ag₆(SO₄)(SiO₄) Hitherto unknown Ag₆(SO₄)(SiO₄) has been prepared at 400–500°C under an oxygen pressure more than 1000 atm. By single crystal X-ray work the structure of tetragonal Ag₆(SO₄)(SiO₄) has been elucidated: a = 7.060, c = 17.660 Å; D?14₁/amd; Z = 4. The crystal structure shows a new type in which the tetrahedrally sulfat- and silicat groups are definite distinguishable. As well the both crystallographic silver positions show a different crystal-chemical character.     

Darstellung,Kristallstrukturen und Schwingungsspektren von [OsBr(acac)(PPh3)] und [OsBr(acac)(AsPh3)]

Synthesis, Crystal Structures, and Vibrational Spectra of [OsBr(acac)(PPh₃)] and [OsBr(acac)(AsPh₃)] By reaction of tetrabromoacetylacetonatoosmate(IV) with PPh₃ or AsPh₃ in ethanol the complexes [OsBr(acac)(PPh₃)] ( 1 ) and [OsBr(acac)(AsPh₃)] ( 2 ) are formed, which are purified by chromatography on silica gel. X-ray structure determinations of single crystals of ( 1 ) (monoclinic, space group P 2₁/n, a = 13.035(2), b = 18.2640(14), c = 16.636(3) Å, β = 112.776(14)°, Z = 4) and ( 2 ) (monoclinic, space group P 2₁/c, a = 13.23(5), b = 18.35(2), c = 16.65(2) Å, β = 112.9(5)°, Z = 4) result in mean bond distances Os–P = 2.413, Os–As = 2.483, Os–Br = 2.488 and Os–O = 2.037 Å. The vibrational spectra (10 K) exhibit the inner ligand vibrations of the acac, PPh₃ and AsPh₃ groups with nearly constant frequencies and the stretching vibrations of OsP at 499–522, of OsAs at 330–339, of OsBr at 213–214 and of OsO in the range 460–694 cm^–1.     

Synthesis and structures of gallium amido imido phenyl clusters (PhGa)(4)(NH(i)Bu)(4)(N(i)Bu)(2) and (PhGa)(7)(NHMe)(4)(NMe)(5)

The phenylgallium-containing clusters constructed with bridging imido and amido ligands, (PhGa)(4)(NH(i)Bu)(4)(N(i)Bu)(2) (1) (51% yield) and (PhGa)(7)(NHMe)(4)(NMe)(5) (2) (31% yield), were synthesized from the room-temperature reactions of bis(dimethylamido)phenylgallium, [PhGa(NMe(2))(2)](2), with isobutylamine and methylamine, respectively. The reaction of [PhGa(NMe(2))(2)](2) in refluxing isobutylamine (85 degrees C) afforded (Ph(2)GaNH(i)Bu)(2) as one of the products, while the reaction of [PhGa(NMe(2))(2)](2) with methylamine at 150 degrees C afforded compound 2 in only 9% yield. Compound 1 possessed an admantane-like Ga(4)N(6) core, whereas compound 2 had a novel Ga(7)N(9) core constructed with both chair- and boat-shaped Ga(3)N(3) rings. The presence of several isomers of compounds 1 and 2 in solution is discussed along the structural similarities with other known gallium-nitrogen clusters and with gallium nitride.     

Darstellung und Charakterisierung von Organodilithiumphosphiden. Die Kristallstruktur von [Li(THF)(TMEDA)P(H)Mes]

Synthesis and Characterization of Organodilithium Phosphides. The Crystal Structure of [Li(THF)(TMEDA)P(H)Mes] t-BuPH₂ and MesPH₂ can be reacted with two equivalents n-BuLi at R. T. in Et₂O/n-hexane to yield the corresponding organodilithium phosphides t-BuPLi₂ ( 1 ) and MesPLi₂ ( 2 ). 1 and 2 can be isolated solvent-free as bright orange-yellow solids. 1 and 2 were characterized by NMR, IR, and RE spectra. When MesPH₂ is treated with one equivalent of n-BuLi, MesP(H)Li is crystallizing as [Li(THF)(TMEDA)P(H)Mes] ( 3 ) from THF/TMEDA/n-pentane in the space group P2₁/n with a = 893.41(6), b = 1 734.7(1), c = 1 391.1(1) pm and β = 90.613(6)°.     

Transient mixed-valence character of Re(I)(4)(CO)(12)(4,4'-bpy)(4)Cl(4)

This study addresses, in detail, the orbital nature and the extent of metal-metal communication in the lowest emitting triplet state of Re(4)(CO)(12)(4,4'-bpy)(4)Cl(4) (where 4,4'-bpy = 4,4'-bipyridine) as well as the symmetry of the lowest (3)MLCT manifold in comparison to that of the ground state. All spectral evidence points to (1). a (3)MLCT excited manifold localized between a single Re(I) corner and an adjacent bridging ligand, (2). a transient mixed-valence state that is completely localized between a single transiently oxidized Re center and the adjacent metals, and (3). a second-order charge transfer from a localized transiently reduced bridging ligand to the adjacent Re(I) center to which it is attached, effectively lowering its oxidation state. The orbital nature of the lowest (3)MLCT manifold is fully corroborated by a molecular orbital diagram derived from quantum chemical modeling studies, while the existence of the localization, localized mixed valency, and second-order charge transfer rely on spectral evidence alone. This work makes use of low-temperature time-resolved infrared (TRIR) techniques as well as a luminescence study. Many of the nuances of the luminescence and TRIR data interpretation are extracted from statistical analysis and quantum chemical modeling studies. The relative concentrations of the dominant conformers that exist for Re(4)(CO)(12)(4,4'-bpy)(4)Cl(4) have also been estimated from Boltzmann statistics.     

Katalytische oxidation von cyclohexen mit IrCl(CO)(PPh3)2 und kritische hydroperoxidkonzentration

Cyclohexene, dissolved in benzene is homogeneously oxidised with IrCl(CO)(PPh₃)₂ as catalyst. No induction period is observed if the concentration of hydroperoxide has a critical value. The reaction rate r increases with the concentration of cyclohexene from r = 1 to 15 mMol O₂ l^?1 min^?1 in pure cyclohexene with turnover numbers of 3000. Product composition is practically independent of the catalyst and cyclohexene concentrations.     

Synthese,IR-Spektrum und Kristallstruktur von PPh4[OsCl4(NO)(NSCl)]

Synthesis, I.R. Spectrum, and Crystal Structure of PPh₄[OsCl₄(NO)(NSCl)] Molten trithiazyl chloride reacts with OsCl₃(NO) to yield a product mixture consisting mainly of S₄N₃[OsCl₄(NO)(NSCl)] and S₄N₃Cl. Extraction of this mixture with a solution of tetraphenylphosphonium chloride in dichloromethane affords green (PPh₄)₂[OsCl₅(NO)] · 2 CH₂Cl₂ and the red title compound. PPh₄[OsCl₄(NO)(NSCl)] was characterized by its IR spectrum and an X-ray crystal structure analysis (3001 independent observed reflexions, R = 0.048). Crystal data: monoclinic, space group P2₁/c, Z = 4, a = 1716, b = 1054, c = 1588 pm, β = 96.25°. The compound consists of PPh₄⊕ cations and [OsCl₄(NO)(NSCl)]? anions in which the nitrosyl and the chlorothionitrene ligands have a cis arrangement. Due to positional disorder the NO and NSCl groups are superimposed statistically in the structure model.     

The Pd(4)(dppm)(4)(H)(2)(2+) cluster: a precatalyst for the homogeneous hydrogenation of alkynes

The catalytic properties of the title cluster toward the homogeneous hydrogenation of phenylacetylene, diphenylethyne and phenyl-1-propyne have been investigated as a function of temperature, pressure, solvents, substrate and cluster concentrations, and counterions. The title cluster is a precatalyst that exhibits a good catalytic activity under mild conditions (1 atm of H(2) at 20 degrees C) for the hydrogenation of alkynes and alkenes. For the alkyne substrates, the turnover frequencies (tof's) range between 200 and 500 h(-)(1), and the product distribution varies as: cis-products, 75-90%; trans-products; 0-8% after 3 h of reaction. Based on the graphs -d[substrate]/dt vs [Pd(4)](1/2), the mechanism indicates a cluster dissociation into two dimers (presumably of the type Pd(2)(dppm)(2)(H)(solvent)(+)). The variations of tof (or -d[substrate]/dt) as a function of [substrate] and pressure of H(2) are linear. At 1600 psi of H(2), the tof can reach 2500-3000 h(-)(1) (in THF). The tof also increases with temperature reaching a maximum at approximately 35 degrees C (tof: 1000-1300 h(-)(1)), but at higher temperatures cluster decomposition begins to occur, leading to a rapid decrease in rates of catalysis. At 50 degrees C, no catalysis is observed. The hydrogenation reaction can be stopped at the corresponding cis-alkenes with approximately 95% yields, depending on the substrate and experimental conditions used. The tof's also vary with the solvent, where stronger coordinating solvent molecules give higher tof's. In addition, the tof's do not change with the nature of the counterion, which acts as "spectator" in the catalysis.     

Über die oxidative Fluorierung von (CF3)(R) (R = CF3, Cl) und die Kristallstruktur von (CF3)(Cl)F+ AsF6−

Oxidative Fluorination of (CF₃)(R) (R = CF₃, Cl) and the Crystal Structure of (CF₃)(Cl) F⁺ AsF₆^? Oxidative fluorination of (CF₃)(R) (R = CF₃, Cl) with XeF⁺MF₆^? (M = As, Sb) in anhydrous HF results in formation of monofluorsulfonium hexafluorometalates. The salts are characterized by vibrational, NMR, and mass spectra. (CF₃)(Cl)F⁺ AsF₆^? crystallizes in the monoclinic space group P2₁/c with a = 9.955(10) Å, b = 11.050(5) Å, c = 12.733(15) Å, β = 97.77(5)°, and Z = 4.     

From fullerene-mixed peroxide to open-cage oxafulleroid C(59)(O)(3)(OH)(2)(OO(t)()Bu)(2) embedded with furan and lactone motifs

[reaction: see text] Removal of one carbon atom from the C60 cage is achieved under mild conditions. The process involves the formation of fullerene-mixed peroxide, subsequent Lewis acid induced cleavage of O-O and C-O bonds, and thermolysis at 75 degrees C. In the proposed mechanism, the carbon atom is deleted as CO and an oxygen atom occupies the vacancy to form a furan ring. Single-crystal X-ray analysis confirmed the results.