Synthese und NMR-Spektren von Nonafulven sowie Vergleich mit 10-Phenylnonafulven

Synthesis and NMR Spectra of Nonafulvene and Comparison with 10-Phenylnonafulvene Experimental procedures for the reaction of cis,cis,cis,trans-cyclononatetraenide (ccct-CNT^?; see 4 ) with bromomethyl acetate ( 1a , R = H, X = Br) to give (cyclononatetraenyl)methyl acetate ( 5a ; 84% yield) as well as for the base-induced elimination of HOAc from 5a to give nonafulvene ( 6a ; 44% yield) are described. Spectroscopic as well as chemical evidence for 6a and 6b is presented. An approximate high-field-NMR analysis of 6a and 6b has been completed. The results are in favour of a fast interconversion of the type 6A?6B (Scheme 4), and supported by the MNDO-optimised geometry of 6a . The first X-ray analysis of a cyclononatetraene (i.e. of 5b ) has been accomplished: 5b is a polyolefinic molecule with largely alternating bond lengths and with a nine-membered ring deviating strongly from planarity.     

trans-[RuCl2(phosphane)2(1,2-diamine)] and Chiral trans-[RuCl2(diphosphane)(1,2-diamine)]: Shelf-Stable Precatalysts for the Rapid,Productive, and Stereoselective Hydrogenation of Ketones

A turnover number (TON) of 2 400 000 and a turnover frequency (TOF) of 63 s⁻¹ are achieved with the chiral Ru^II complex 1 (R=p-CH₃C₆H₄) in the asymmetric hydrogenation of acetophenone. Carbonyl-selective asymmetric hydrogenation of α,β-unsaturated ketones proceeds in the presence of these Ru^II catalysts, and 4-substituted cyclohexanones are selectively converted into cis alcohols.     

Asymmetric torsional potential function and conformational analysis of furfural by far infrared and Raman spectroscopy

The far i.r. (400-50 cm⁻¹) spectra of gaseous and solid furfural (2-furancarboxaldehyde), c-C₄H₃O (CHO), have been recorded. Additionally, the Raman (3500-20 cm⁻¹) spectra of the gas and liquid have been obtained at variable temperatures and the spectrum of the solid at 25 K. These data have been interpreted on the basis that the molecule exists in two different conformations in the fluid states and that the conformation which has the two oxygen atoms oriented in a trans configuration, OO-trans, is most stable (ΔH ⩽ 1 kcal/mol) in the gas; however, the conformation which has the two oxygen atoms oriented cis, OO-cis, is preferred in the liquid (ΔH = 1.07 ± 0.03 kcal/mol) and is the only rotamer present in the spectra of the solid. The asymmetric torsional fundamental for the OO-trans rotamer has been observed at 146.25 cm⁻¹ in the far i.r. spectrum of the vapor and has five accompanying “hot bands”. The corresponding fundamental for the OO-cis rotamer has been observed at 127.86 cm⁻¹ along with a “hot band” which occurs at 127.46 cm⁻¹. From these data a cosine-based potential function governing internal rotation of the CHO top has been determined and the potential coefficients have values of V₁ = 173 ± 2, V₂ = 3112 ± 20, V₃ = 113 ± 2 and V₄ = −198 ± 6 cm⁻¹. This potential is consistent with an enthalpy difference between the more stable OO-trans and high energy OO-cis conformers being 286 ± 24 cm⁻¹ (818 ± 67 cal/mol) and a trans to cis barrier height of 3255 ± 20 cm⁻¹ (9.31 ± 0.06 kcal/mol). These results are compared to the corresponding quantities obtained previously from microwave spectroscopy and theoretical methods.     

Stereochemistry of alkyl 3-substituted 4-halotetrahydro-2-oxo-3-furancarboxylates: 2—1H and 13C NMR spectra

The ¹H NMR parameters of methyl 3-substituted cis-4-halotetrahydro-2-oxo-3-furancarboxylates are reported, with assignments of the ring protons based on solvent-induced changes in the vicinal trans coupling constants, ³J(H-4, H-5). Preferred conformations, ce with a pseudo-equatorial halogen for the cis isomers and ta with a pseudo-axial halogen for the trans isomers, have been suggested on comparison of the magnitudes of J(trans) and J(gem) in both series. The ³J(¹³CH₃, H-4) values measured for methyl cis-4-bromotetrahydro-3-methyl-3-furancarboxylate, methyl trans-4-bromotetrahydro-3-methyl-3-furancarboxylate and trans-3,4-dibromodihydro-3-methyl-2(3H)-furanone have confirmed the stereochemical assignments.     

Structure of 2(5)-alkyl-4-hydroxy-3,4-diphenylcyclopent-2-en-1-ones,cyclocondensation products of benzil with aliphatic ketones

The reaction of benzil with methyl alkyl ketones gave three isomeric cyclopentenone derivatives, 2-substituted and cis- and trans-5-substituted 4-hydroxy-3,4-diphenylcyclopent-2-en-1-ones. cis- and trans-2,5-Disubstituted 4-hydroxy-3,4-diphenylcyclopent-2-en-1-ones were formed in analogous reaction of benzil with dialkyl ketones. The structure of the products was confirmed by ¹H NMR spectroscopy and molecularmechanics calculations.     

Novel Octahedral Bis[2‐(1‐aziridinyl)ethanol‐κ2N,O] Complexes of Cobalt(II)

The synthesis and molecular structure of trans‐{bis[(acetato‐κO)‐(2‐(1‐aziridinyl)ethanol‐κ²N,O)]}cobalt(II) ( 4 ) and cis‐{bis[chlorido‐(2‐(1‐aziridinyl)ethanol‐κ²N,O)]}cobalt(II) ( 5 ) is reported. Both neutral chelate complexes are prepared from the corresponding Co^II salt [CoX₂; X = OAc ( 1 ), Cl ( 2 )] and 2‐(1‐aziridinyl)ethanol (azolH, 3 ) in dry dichloromethane. A third, ionic complex, cis‐{bis[aqua‐(2‐(1‐aziridinyl)ethanol‐κ²N,O)]}cobalt(II) diacetate ( 6 ) is formed from 4 in the presence of water and could be crystallized from aqueous dichloromethane. In all cases, 2‐(1‐aziridinyl)ethanol is coordinating as bidentate chelate ligand by the nitrogen and oxygen atom of the aziridinyl and hydroxy moiety. After purification, the compounds have been fully characterized using IR spectroscopy and FAB⁺‐MS. The single‐crystal X‐ray structure analysis revealed a distorted octahedral geometry for all complexes with either trans ( 4 ) or cis ( 5 , 6 ) configuration.     

Unusual Structures of the Parent Molecules Diarsene,Distibene, and Dibismuthene: Toward Their Observation

There is considerable interest, from both experimental and theoretical perspectives, in molecules incorporating multiple bonds between main group elements. Herein, we not only consider the parent molecules HE=EH (E=As, Sb, Bi), but also a number of their isomers. For each E₂H₂ molecule, a number of different structures were optimized with four different DFT methods. Final structures were determined with the coupled cluster method CCSD(T) using large basis sets, namely cc-pVQZ-PP, incorporating relativistic psuedopotentials. All feasible dissociation pathways are examined. For all three E₂H₂ molecules the trans isomer lies lowest in energy, with the cis isomer higher by 2.7 (As), 2.1 (Sb), and 1.8 (Bi) kcal mol⁻¹, respectively. However, both cis and trans structures should be observable, as large barriers (27.7, 20.5, and 17.7 kcal mol⁻¹) separate them. For both the cis and trans structures, in the infrared the strong E-H stretching frequencies should also be observable. Only the cis structures have dipole moments (0.62, 0.01, and 0.83 debye, respectively), and their observation by microwave spectroscopy would be stunning. Also considered were the higher energy vinylidene-like, pyramidal, monobridged, and linear structures. We conclude that molecules such as HSb=SbH-Fe(CO)₄, HBi=BiH-Fe(CO)₄, and related systems, should be feasible synthetic targets.     

An improved method for the polymerization of ethynylferrocene. Conducting properties of doped polyethynylferrocene

The catalytic activity of the [Rh(cod)Cl]₂ complex (cod  cis, cis-cyclo-octa-1,5-diene) with respect to the polymerization of ethynylferrocene (EFc) was examined. A good yield (about 80%) of polyethynylferrocene (PEFc) was obtained in benzene by addition of sodium hydroxide as co-catalyst. PEFc was insoluble in most organic solvents. The conductivity (s̀) of the undoped polymer is about 10⁻¹¹ ohm⁻¹ cm⁻¹; upon doping PEFc with iodine in tetrahydrofuran the conductivity can be increased to 10-100 ohm⁻¹ cm⁻¹. The influence of other doping agents was also examined.     

Molecular Engineering of Chalcogen-Embedded Anthanthrenes via peri-Selective C−H Activation: Fine-Tuning of Crystal Packing for Organic Field-Effect Transistors

Disclosed herein is a RhCl₃-catalyzed peri-selective C−H/C−H oxidative homo-coupling of 1-substituted naphthalenes, which provides a highly efficient and streamlined approach to chalcogen-embedded anthanthrenes from readily available starting materials. Introducing O, S, and Se into the anthanthrene skeleton leads to gradually increased π–π stacking distances but significantly enhanced π–π overlaps with the growth of the hetero-atom radius. Moderate π–π distance, overlap area, and intermolecular S−S interactions endow S-embedded anthanthrene ( PTT ) with excellent 2D charge-transport properties. Moreover, the transformation of p-type to n-type S-embedded anthanthrenes is realized for the first time via the S-atom oxidation from PTT to PTT-O4 . In organic field-effect transistor devices, PTT derivatives exhibit hole transport with mobilities up to 1.1 cm² V⁻¹ s⁻¹, while PTT-O4 shows electron transport with a mobility of 0.022 cm² V⁻¹ s⁻¹.     

Conformational analysis,barriers to internal rotation,ab initio calculations and vibrational assignment of fluoroacetone

The infrared (3500-20 cm⁻¹) and Raman (3200-10 cm⁻¹) spectra have been recorded for gaseous and solid fluoroacetone (1-fluoro-2-propanone), CH₂FC(O)CH₃. Additionally, the Raman spectrum of the liquid has been recorded and qualitative depolarization values have been obtained. These data have been interpreted on the basis that the molecule exists predominantly in the cis (fluorine atom oriented cis to the methyl group) conformation in the vapor but for the liquid a second conformer having a trans orientation (fluorine atom oriented trans to the methyl group) is present. From a study of the Raman spectrum of the liquid at variable temperatures the trans conformation has been determined to be more stable than the cis form by 416 ± 54 cm⁻¹ (1.19 ± 0.15 kcal mol⁻¹) and is the only conformation present in the spectrum of the annealed solid. The asymmetric torsional fundamental for the more stable cis conformer has been observed in the far infrared spectrum of the gas at 69.6 cm⁻¹ with six accompanying hot band transitions proceeding to lower frequency. The corresponding mode for the high energy trans conformer is extensively overlapped but is distinguishable at ∼65 cm⁻¹. From these data the asymmetric torsional potential function governing internal rotation about the CC bond has been determined and the potential coefficients are: V₁ = 675 ± 2, V₂ = 991 ± 5, V₃ = 74 ± 1 and V₄ = 54 ± 2 cm⁻¹. The cis to trans and trans to cis barriers are 1332 ± 5 and 731 ± 5 cm⁻¹, respectively, with an enthalpy difference of 601 ± 8 cm⁻¹ (1.72 ± 0.02 kcal mol⁻¹). From ab initio calculations at the 3-21G and 6-31G* basis set levels optimized geometries for both the cis and trans conformers have been obtained and the potential surface governing internal rotation of the asymmetric top determined. The observed vibrational frequencies with their assignments for both the cis and trans conformers are compared to those from the ab initio calculations. All of these results are compared to the corresponding quantities for some similar molecules.     

Stereochemistry of cycloadducts from 3,4-dihydro-6,7-dimethoxyisoquinoline ylide and olefins

Cycloaddition of 2-methoxycarbonylmethyl-3,4-dihydro-6,7-dimethoxyisoquinolinium ylide with various E-substituted olefin type dipolarophiles gave products of 10b-H, 1-H, 2-H and 3-H α,α,β,β-relative configuration with one exception. Relative configuration of compounds prepared has been determined by 1D and 2D ¹H and ¹³C nmr techniques. It has also been detected that a triple trans ? cis-1 ? cis-2 conformation equilibrium exists in solution.     

Dinuclear complexes with a μ-cyano ligand. part IX. synthesis,characterization and magnetic studies of several derivatives of [Cr(CN)6]3− and [Cr(NO)(CN)5]3−

Summary Twelve dinuclear complexes, each with a bridging cyano group, of formulaecis-M[(aa)₂FCr-NC-Cr(CN)₅] andcis- M[(aa)₂FCr-NC-CrNO(CN)₄] (aa=ethylenediamine or 1,3-diaminopropane; M=K⁺, Na⁺ or NH ₄ ⁺ ) have been prepared by solid state heating of the corresponding doubly complexed saltstrans-M[CrF(H₂O)(aa)₂][Cr(CN)₆] andtrans-M [CrF(H₂O)(aa)₂][CrNO(CN)₅]. All have been characterized by chemical analysis, electronic and i.r. spectra and conductivity measurements.Magnetic susceptibilities down to liquid helium temperature have been determined forcis-K[(en)₂FCr-NC-Cr(CN)₅],cis-K[(tn)₂FCr-NC-Cr(CN)₅] andcis-K[(en)₂FCr-NC-CrNO-(CN)₄]. Slight antiferromagnetic interactions have been found in the first two compounds (J=–1.4 and –1.2 cm^–1, respectively). Thecis-K[(en)₂FCr-NC-CrNO(CN)₄] compound behaves as a Curie paramagnet and a structural model is proposed to explain this fact.     

Saturated nitrogen-containing heterocycles. 15. Catalytic synthesis and isomerization of 9-substituted10-methylperhydroacridines

In the catalytic hydromethylamination of 8-substituted 2-hydroxytricyclo[7.3.1.0^2,7]tridecane-13-ones they are converted into 9-substituted 10-methyl-^9,9a-dodecahydroacridines and 10-methylperhydroacridines with trans,anti,cis- and cis,syn,cis-conformation. The ability of the latter to isomerize into the trans,cis,tans-form has been established.For Communication 14, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 200–204, February, 1992.     

Tetracarbonyl group 6 complexes containing secondary and tertiary phosphines

The mixed ligand tetracarbonyl derivatives, cis-M(CO)₄(PPh₂H)(PPh₃) (M  Cr, Mo, W) and cis-W(CO)₄(PPh₂H)(L) (L  PEt₃, PEt₂Ph, PEtPh₂) have been prepared from the reaction of M(CO)₅PPh₂H with L in THF in the presence of potassium t-butoxide. These reactions are accompanied in most instances by the formation of [W(CO)₅PPh₂]⁻, [(OC)₅M(μ-PPh₂)M(CO)₅]⁻, [(OC)₅M(μ-PPh₂)-M(CO)₄(PPh₂H)]⁻, [(OC)₄M(μ-PPh₂)₂M(CO)₄]²⁻, (OC)₄M(μ-PPh₂)₂M(CO)₄, and cis-M(CO)₄(PPh₂H)₂.     

Copper(II) complexes of 6-methyl-2-acetylpyridine N(4)-substituted thiosemicarbazones

Summary Copper(II) complexes of 6-methyl-2-acetylpyridine N(4)-substituted thiosemicarbazones, coordinated either as a neutral or a monoanionic ligand, have been prepared and characterized. I.r., electronic and e.p.r. spectra of the complexes, as well as¹H- and¹³C-n.m.r. spectra of the thiosemicarbazones, have been recorded. Both the thiosemicarbazones and their copper(II) complexes show either modest or no growth inhibitory activity againstAspergillus niger, but theN(4)-dialkyl- and 3-azacyclo-derivatives, and particularly their copper(II) complexes, have considerable activity againstPaecilomyces variotii.     

The Triplet Hydroxyl Radical Complex of Phosphorus Monoxide

Phosphorus monoxide (^.PO) is a key intermediate in phosphorus chemistry, and its association with the hydroxyl radical (^.OH) to yield metaphosphorous acid (cis-HOPO) contributes to the chemiluminescence in the combustion of phosphines. When photolyzing cis-HOPO in an Ar-matrix at 2.8 K, the simplest dioxophosphorane HPO₂ and an elusive hydroxyl radical complex (HRC) of ^.PO form. This prototypical radical-radical complex reforms into cis-HOPO at above 12.0 K by overcoming a barrier of 0.28±0.02 kcal mol⁻¹. The vibrational spectra of this HRC and its D- and ¹⁸O-isotopologues suggest a structure of ^.OH⋅⋅⋅OP^., for which a triplet spin multiplicity with a binding energy of −3.20 kcal mol⁻¹ has been computed at the UCCSD(T)-F12a/aug-cc-pVTZ level.     

Determination of the rate constants for the gas-phase reactions of methyl butenol with OH radicals,ozone, NO3 radicals,and Cl atoms

Using a relative rate method, rate constants for the gas-phase reactions of 2-methyl-3-buten-2-ol (MBO) with OH radicals, ozone, NO₃ radicals, and Cl atoms have been investigated using FTIR. The measured values for MBO at 298±2 K and 740±5 torr total pressure are: k_OH=(3.9±1.2)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹, k_O3=(8.6±2.9)×10⁻¹⁸ cm³ molecule⁻¹ s⁻¹, k=(8.6±2.9)×10⁻¹⁵ cm³ molecule⁻¹ s⁻¹, and k_Cl=(4.7±1.0)×10⁻¹⁰ cm³ molecule⁻¹ s⁻¹. Atmospheric lifetimes have been estimated with respect to the reactions with OH, O₃, NO₃, and Cl. The atmospheric relevance of this compound as a precursor for acetone is, also, briefly discussed. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 589–594, 1998     

Stereoselective synthesis of (±)-indolizidines 167B and 209D and theirtrans-isomers based on the reductive allylboration of pyridine

A general method for the synthesis of 5-substituted indolizidines based on intramolecular cyclization oftrans- andcis-2-allyl-6-R-1,2,3,6-tetrahydropyridines, obtained from pyridine and triallylborane, has been elaborated. The closure of the five-membered ring is carried out by hydroboration-oxidation followed by cyclization of the resulting δ-amino alcohols in the presence of the Ph₃P−CBr₄−Et₃N system. (Pr₂BH)₂ and Pr₃B are used as the hydroborating reagents, and H₂O₂ in an acid medium is used for the oxidation of 2-[3-(dipropylboryl]-Δ²-piperideines formed. This method has been used for the synthesis of two natural alkaloids: indolizidine 209D (cis-5-hexylindolizidine) and itstrans-isomer were prepared fromcis- andtrans-2-allyl-6-hexyl-1,2,3,6-tetrahydropiridine, respectively; indolizidine 167B andtrans-5-propylindolizidine were synthesized fromcis- andtrans-2,6-diallyl-1,2,3,6-tetra-hydropyridine, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 971–979, May, 1998.     

Synthesis and complexing properties ofcis,cis-1,3,5-tri-[2-(diphenylphosphinyI)ethylamino]cyclohexane

A novel polydentate phosphorus-containing complexing agent,cis,cis-1,3,5-tri[2-(diphenyl-phosphinyl)ethylamino]cyclohexane, has been prepared on the basis ofcis,cis-1,3,5-triamino-cyclohexane. The method of potentiometric titration in an aqueous—organic medium (70% ethanol, ionic strength 0.01M LiNO₃, 298 K) has been used to study the acid-base and complexing properties of the title compound. The ligand thus prepared forms 11 complexes with Cu²⁺, Co²⁺, Zn²⁺, and Ni²⁺ cations; formation of hydroxocomplexes MOHL⁺ has been observed in the case of Zn²⁺ and Cd²⁺.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1276–1279, July, 1993.The authors are grateful to A. G. Matveeva for his assistante in discussing the results of this study and in preparing this paper.     

Rate constants for the gas-phase reaction of ozone with 1, 1-disubstituted alkenes

The gas-phase reaction of ozone with eight alkenes including six 1,1-disubstituted alkenes has been investigated at ambient T (285–298 K) and p = 1 atm. of air. The reaction rate constants are, in units of 10⁻¹⁸ cm³ molecule⁻¹ s⁻¹, 9.50 ± 1.23 for 3-methyl-1-butane, 13.1. ± 1.8 for 2-methyl-1-pentene, 11.3 ± 3.2 for 2-methyl-1,3-butadiene (isoprene), 7.75 ± 1.08 for 2,3,3-trimethyl-1-butene, 3.02 ± 0.52 for 3-methyl-2-isopropyl-1-butene, 3.98 ± 0.43 for 3,4-diethyl-2-hexene, 1.39 ± 17 for 2,4,4-trimethyl-2-pentene, and >370 for (cis + trans)-3,4-dimethyl-3-hexene. For isoprene, results from this study and earlier literature data are consistent with: k (cm³ molecule⁻¹ s⁻¹) = 5.59 (+ 3.51, &minus 2.16) × 10⁻¹⁵ e^{(−3606±279/RT)}, n = 28, and R = 0.930. The reactivity of the other alkenes, six of which have not been studied before, is discussed in terms of alkyl substituent inductive and steric effects. For alkenes (except 1,1-disubstituted alkenes) that bear H, CH₃, and C₂H₅ substituents, reactivity towards ozone is related to the alkene ionization potential: In k<(10⁻¹⁸ cm³ molecule⁻¹ s⁻¹) = (32.89 ± 1.84) − (3.09 ± 0.20) IP (eV), n = 12, and R = 0.979. This relationship overpredicts the reactivity of C_≥3 1-alkenes, of 1,1-disubstituted alkenes, and of alkenes with bulky substituents, for which reactivity towards ozone is lower due to substituent steric effects. The atmospheric persistence of the alkenes studied is briefly discussed. © 1996 John Wiley & Sons, Inc.