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Carbene transfer from aliphatic diazoalkanes upon coordinatively unsaturated metal centers is a general synthetic concept that provides straight-forward routes into organo-metallic hydrocarbon chemistry. A comparison focussing on several key reactions of general applicability demonstrates that mononuclear organometal substrates add carbenes that may act as bridging ligands (e.g., compound 6) if they arise from ω,ω'-bisdiazoalkanes. By way of contrast, metal-metal double bonds cleanly form dimetallacyclo-propane-type derivatives under very mild conditions (7-9). The broadest variety of structures is finally encountered with metal-metal triply bonded precursors such as the molybdenum compounds 3: here, the initial diazoalkane adducts are subject to further rearrangement processes commonly leading to metal-metal single bonds (11) or causing irreversible cleavage of the dinuclear metal systems (10).
Thermal decompositions of azo compounds in the gas phase under reduced pressure are further investigated using photoelectron spectroscopic gas analysis. Passing diallyl, diphenyl and phenylmethyl derivatives either through a short-pathway pyrolysis (SPP) apparatus or through an external thermal reactor (ETR) results in the following fragmentations: Under nearly unimolecular conditions (SPP, 10-4 mbar pressure), diallyldiazene decomposes above 600 K to N2 and hexadiene-1,5 with the allyl radical as a detectable intermediate. The PE spectra recorded for diphenyldiazene above 1000 K (ETR, 1-2 mbar pressure) show N2, benzene, as well as traces of diphenyl. Phenylmethyldiazene yields above 800 K (SPP) predominantly N2, toluene, diphenyl and ethane with the methyl radical as the only detectable intermediate. Insertion of quartz wool into the pyrolysis tube (ETR) lowers the fragmentation temperatures, and in addition, above 850 K, HCN and aniline are PE spectroscopically identified. Surprisingly, this second reaction channel can be heterogeneously catalyzed: phenylmethyldiazene decomposes under 10-2 mbar pressure at a [Ni/SiO2] catalyst surface selectively to HCN and aniline.
[Ph3PN(H)Ph][AuI2] (2) is formed by the reaction of AuI with N-Phenyl-iminotriphenylphosphorane, Ph3PNPh in a toluene suspension. 2,3-Bis(triphenylphosphinimino)maleic acid-N-methylimide (3) has been prepared by the Staudinger reaction of 2,3-bis(azido)maleic acid-N-methylimide with PPh3 in THF solution in the form of red crystals. Crystal structure determinations of three iminophosphoranes were carried out by X-ray methods.
Ph3PNPh (1): space group P21/c, Z = 4, 2176 independent observed reflexions, R = 0.057. Lattice dimensions (-30 °C): a = 1126.4, b = 1148.6, c = 1476.0 pm; β = 97.21°. The compound forms monomeric molecules with P=N = 160.2 pm and an PNC angle of 130.4°.
[Ph3PN(H)Ph][AuI2] (2): space group P1̄, Z = 2, 1780 independent observed reflexions, R = 0.057. Lattice dimensions (18 °C); a = 824.9, b = 1022, c = 1476.2 pm; α = 89.23°, β = 87.41°, γ = 85.65°. The compound consists of ions [Ph3PN(H)Ph]⊕ with P=N = 162.4 pm and PNC = 129.3°, and anions [AuI2]⊖ with Au-I = 261.9 and 259.3 pm, IAuI = 176.8°.
(Ph3P)2N2C4O2 (NMe) (3): space group P1̄, Z = 2, 4972 independent observed reflexions, R = 0.050. Lattice dimensions (-90 °C): a = 904.7, b = 993.8, c = 2017.4 pm; α = 101.55°, β = 96.39°, γ = 105.81°. The compound forms monomeric molecules with syn-conformation of the two NPPh3 groups. Bond lengths: P=N = 157.1; 155.3 pm, bond angles: PNC = 133°; 136°.
The title compounds Ph3PNPh · CuCl (1) and (Ph3P)2 N2 C4O2 (NMe) CuCl (2) have been prepared by the reactions of CuCl with the corresponding phosphoranimines Ph3PNPh and 2.3-bis(triphenylphosphoranylideneamino)maleic acid N-methylimide, respectively. Both com-plexes were characterized by their IR spectra as well as by crystal structure determinations.
Ph3PNPh · CuCl (1): space group P1, Z = 4, 3639 independent observed reflexions, R = 0.038. Lattice dimensions (18 °C): a = 1047.6; b = 1251.5; c = 1755 pm; α = 103.43°; β = 97.24°; γ = 101.30°. The compound forms monomeric molecules; the asymmetric unit contains two crystallo-graphically independent molecules. The CuCl molecule is bonded via the N atom of the phos-phoranimine. Bond lengths: Cu-N = 189 pm; Cu-CI = 209 pm; bond angle N - Cu - CI = 177°.
(Ph3P)2N2C4O2(NMe) · CuCl (2): space group Pbca, Z = 8, 5611 independent, observed reflexions, R = 0.069. Lattice dimensions (25 °C): a = 1224.3; b = 1962.5: c = 2994.0 pm. The compound forms monomeric molecules with the CuCl molecule bonded via one of the N atoms of the phosphoranimine groups. Bond lengths: Cu - N = 194 pm; Cu-CI = 212 pm; bond angle N-Cu -CI -175°.
Infrared spectroscopy in combination with a specially developed attenuated total reflection (ATR) flow cell and multivariate analysis was used for the quantitative analysis of beer and other beverages. IR spectra of samples were obtained in the range from below 1000 cm-1 to 4000 cm-1 and subjected to a multivariate analysis based on calibration sets with laboratory reference standards. In the case of beer, this calibration set included 240 beer samples spanning the entire range of ethanol content, extract and CO2. Based on this calibration, an infrared and UV/Vis spectroscopy-based sensor for the quick and quantitative quality control of beer was developed and subjected to extensive tests in breweries. This sensor meets and exceeds all requirements from brewers for the routine control in the production and bottling. Its use for other beverages, for example wine, juices or apple wine, requires only another set of calibration data for the specific beverage.
Dichlorido(3-phenylindenylidene)bis(triphenylphosphane)ruthenium(II) tetrahydrofuran disolvate
(2011)
The RuII atom in the title compound, [RuCl2(C15H10)(C18H15P)2]·2C4H8O, has a distorted square-pyramidal conformation. The P and Cl atoms are at the base of the pyramid and the Ru-Cindenylidene bond is in the axial position. The two Cl ligands and the two phosphane ligands are in trans positions. The Cl-Ru-Cl and P-Ru-P angles are 157.71 (2) and 166.83 (2)°, respectively. The two independent tetrahydrofuran (THF) solvent molecules are disordered. One THF molecule was refined using a split-atom model. The second THF molecule was accounted for by using program PLATON/SQUEEZE [Spek (2009). Acta Cryst. D65, 148-155]. The molecular conformation shows three intramolecular C-H...Cl contacts and two C-H...[pi] interactions while the crystal packing features an intermolecular C-H...Cl contact and two very weak intermolecular C-H...[pi] contacts.
A new procedure for the synthesis of 2-(4-propylphenyl)ethanol is provided. This new procedure significantly reduces side-products as 1-(4-propylphenyl)ethanol and 2-bromoethanol, which are obtained when using the previously known procedure. Only with the new procedure an efficient purification on the large scale needed for avoided-level-crossing muon-spin resonance experiments was possible.
Structural details of the title compound could be derived from an X-ray structure analysis of a crystalline derivative, the nitrobenzoyl ester.
Crystal and molecular structure analysis of the title compound 1, a most electron rich carbosilane, exhibits a shallow boat conformation for the cyclohexadiene ring which is shielded by four bulky Me3Si groups. Multiple hyperconjugative interaction occurs between the two non-conjugated olefinic π systems and the four rather long (192 pm) carbon-silicon o bonds which form an angle of about 34° with the assumed π axis. The HOMO destabilization caused by this unique structural arrangement explains the energetically facile formation and subsequent reactivity of the cation radical 1+ which was found to undergo oxidative desilylation to the aromatic 1,4-bis(trimethylsilyl) benzene precursor in the single electron transfer reaction with TCNE.
[MesnacnacZn(μ-H)]2 (1) was synthesized by reaction of MesnacnacZnI with either an equimolar amount of KNH(iPr)BH3 or an excess of NaH and characterized by multinuclear NMR and IR spectroscopy as well as X-ray diffraction. Two polymorphs of 1 were found and their structures determined on single crystals.
Starting from (MeO)3SiCH2Cl (10) and Ph2(H)SiCH2OH (16), respectively, the (hydroxymethyl)diphenyl(piperidinoalkyl)silanes (HOCH2)Ph2Si(CH2)2NC5H10 (6) and (HOCH2)Ph2Si(CH2)3NC5H10 (8) have been synthesized [10→Ph2(MeO)SiCH2Cl (11)→Ph2(CH2=CH)SiCH2Cl (12)→Ph2(CH2=CH)SiCH2OAc (13)→Ph2(CH2=CH)SiCH2OH (14)→Ph2(CH2=CH)SiCH2OSiMe3 (15)→6; 16→Ph2(H)SiCH2OSiMe3 (17)→8; NC5H10 = piperidino]. N-Quaternization of 6 and 8 with MeI gave the corresponding methiodides 7 and 9, respectively. As shown by IR-spectroscopic studies, compounds 6 and 8 form intramolecular O-H···N hydrogen bonds in solution (CCl4). In the crystal, 6 (space group Pna21; two crystallographically independent molecules) also forms intramolecular O-H···N hydrogen bonds whereas 8 (space group P1̅) forms intermolecular O-H···N hydrogen bonds leading to the formation of centrosymmetric dimers (single-crystal X-ray diffraction studies). The (hydroxymethyl) silanes 6-9 and the related silanols (HO)Ph2Si(CH2)2NC5H 10 (sila-pridinol; 1), sila-pridinol methiodide (2), (HO)Ph2Si(CH2)3NC5H10 (sila-difenidol; 3) and sila-difenidol methiodide (4) were investigated for their antimuscarinic properties. In functional pharmacological experiments as well as in radioligand competition studies, all compounds behaved as simple competitive antagonists at muscarinic M1-, M2-, M3- and M4-receptors. In general, the silanols 1-4 displayed higher receptor affinities (up to 100-fold) than the corresponding (hydroxymethyl) silanes 6-9 . In the (hydroxymethyl)silane series, compound 7 was found to be the most potent muscarinic antagonist [pA2/pKi= 8,71/8,6 (M1), 8,23/7,8 (M2), 8,19/7,8 (M3); pKi = 8,2 (M4)]. In the silanol series, the related compound 2 showed the most interesting antimuscarinic properties [pA2/pKi = 10,37/9,6 (M1), 8,97/8,8 (M2), 9,08/8,8 (M3); pKi = 9,4 (M4)].