1-Phenyl-1-halo-1-silacyclohexanes

The approaches to synthesis of 1-phenyl-1-halo-1-silacyclohexanes C₅H₁₀Si(Ph)X (X = F, Cl, Br) have been examined. 1-Phenyl-1-chloro-1-silacyclohexane has been prepared via the known reaction of phenyltrichlorosilane with dimagnesium derivative of 1,5-dibromopentane; up to 20% of 1-bromo-1-phenyl-1-silacyclohexane admixture is formed along with the target product. The minor product formation has been prevented using an alternative method of chlorination of 1-phenyl-1-silacyclohexane with N-chlorosuccinimide. 1-Phenyl-1-fluoro-1-silacyclohexane has been obtained in close to quantitative yield via the reaction of 1-phenyl-1-chloro-1-silacyclohexane with SbF₃ and in 70% yield via its reaction with HF. The synthesis of 1-phenyl-1-bromo-1-silacyclohexane via bromination of 1-phenyl-1-chloro-1-silacyclohexane with N-bromosuccinimide has given the target product as a minor one, the major product being disiloxane formed due to hydrolysis of the Si–Br bond.     

Synthesis and characterization of 1-methyl-1-silaindane and 1-methyl-1-germaindane

New synthetic routes to 1-methyl-1-silaindane (1b) and 1-methyl-1-germaindane (1b) were developed and the desired products were obtained in good isolated yield. Compounds 1a and 1b were fully characterized by mass spectroscopy, ¹H and ¹³C{¹H} NMR, and infrared spectroscopy.     

1-Chlor-1-phosphirane

The title compounds are prepared by reaction of disubstituted diazomethanes with 1-chloro-2-phenyl-2-trimethylsilyl-1-phosphaalkene. The chemistry of the 1-chloro-1-phosphiranes is described.     

Nuclear-substituted 1-phenyl-1-methyl-1-silacyclobutane derivatives

Conclusions The synthesis of some nuclear-substituted derivatives of 1-phenyl-1-methyl-1-silacyclobutane by the reaction of 1-methyl-1-chloro-1-silacyclobutane with the appropriate arylmagnesium bromides was described.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1686–1688, July, 1978.     

1-Methyl-1-ethynylsilacyclopentane

Conclusions We synthesized 1-methyl-1-ethynylsilacyclopentane, which is the first reported 1-ethynylsilacycloalkane. The reactivities of this silahydrocarbon and its magnesium bromide derivative were studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1403–1406, June, 1987.     

1-乙酰胺基丙叉-1,1-二膦酸和1-丙酰胺基乙叉-1,1-二膦酸与碱土金属离子的螯合作用

用pH电位法研究了1-乙酰胺基丙叉-1,1-二膦酸(S-186)和1-丙酰胺基乙叉-1,1-二膦酸(S-106)与碱土金属的螯合作用(30±O.1℃).当金属离子与配体的摩尔浓度比为10∶1、1∶1和1∶2时,在水溶液中形成了MHL、ML、ML_2和M_2L等几种类型的配合物.分别测定了它们的稳定常数,其中S-186配合物稍高于S-106,说明配合物稳定性与螯合剂的碱度有平行关系.值得注意的是,这两种螯合剂与Sr~(2 )形成的双核配合物的稳定性均较其它碱土金属离子的为高.     

1-Trimethylsilyl-, 1-Trimethylgermyl- und 1-Trimethylstannyl-3,4-dimethylphospholen

1-Trimethylsilyl-, 1-Trimethylgermyl-, and 1-Trimethylstannyl-3,4-dimethylphospholene 1-Lithium-3,4-dimethylphospholen reacts with Me₃SiCl and Me₃GeCl yielding 1-trimethylsilyl-3,4-dimethylphospholene ( 1 ) and 1-trimethylgermyl-3,4-dimethylphospholene ( 2 ) respectively. 2 and 1-trimethylstannyl-3,4-dimethylphospholene ( 3 ) are formed using the reaction of 1 with Me₃GeCl and Me₃SnCl respectively. The ¹H, ¹³C and ³¹PNMR-spectra as well as the mass spectra of the new compounds are discussed.     

The mechanism of thermal dehydrochlorination. Pyrolysis of 1-Chloro-1-fluoroethane and 1-chloro-1, 1-difluoroethane

The thermal decompositions of 1-chloro-1-fluoroethane and 1-chloro-1,1-difluorethane at atmospheric pressure have been studied in the temperature range 500–600°C in a flow system. The dehydrochlorinations are homogenous in a carbonaceous reactor and unimolecular. The rate constants are given by and The criteria for molecular or chain processes in thermal dehydrochlorinations are discussed.     

1, 1-Difluoro-1H-cyclopropa[a]naphthalene

1, 1-Difluorocyclopropa[a]naphthalene ( 1b ) is prepared in three steps from 4-bromo-1,2-dihydronaphthalene ( 7 ) via carbene addition, benzylic bromination and bidehydrohalogenation. Structural evidence for formation of 1b is based on ¹H- and ¹⁹F-NMR spectroscopy. Compound 1b is stable in solution at ?30°. Upon reaction with MeOH/H⁺ it is converted to a 1:2 mixture of 1- and 2-methylnaphthoate ( 10 and 11 , respectively).     

1:1 alternating copolymers of 1-bicyclobutanecarbonitrile with styrene

High molecular weight, 1:1 alternating copolymers of 1-bicyclobutanecarbonitrile with styrene were prepared in tetramethylenesulfone solution by complexing the electron-poor bicyclobutane monomer with zinc chloride. Methyl 1-bicyclobutanecarboxylate under these conditions gave copolymers containing a slight excess of styrene units (ratio 1:1.3 to 1:1.8). High molecular weight homopolymers of 1-bicyclobutanecarbonitrile and of methyl 1-bicyclobutanecarboxylate were prepared similarly. The tendency of the bicyclobutane nitrile to form 1:1 alternating copolymers is as great as that of its vinyl analog, acrylonitrile, and the synthesis of other alternating copolymers from this monomer should be possible.     

The X˜1A1, a˜3B1, a˜1B˜1, and B˜1A1 electronic states of SiH2

Four electronically low-lying states of silylene (SiH₂) have been studied systematically using high level ab initio electronic structure theory. Self-consistent field (SCF), two-configuration (TC) SCF, complete active space (CAS) SCF, configuration interaction with single and double excitations (CISD), and CASSCF second-order (SO) CI levels of theory were employed with eight distinct basis sets. The zeroth-order wave functions of the ground (X˜ ¹A₁ or 1 ¹A₁) and B˜ ¹A₁ (or 2 ¹A₁) excited states are appropriately described by the first and second eigenvectors of the TCSCF secular equations. The TCSCF-CISD, CASSCF, and CASSCF-SOCI wave functions for the B˜ ¹A₁ (or 2 ¹A₁) state were obtained by following the second root of the CISD, CASSCF, and SOCI Hamiltonian matrices. At the highest level of theory, the CASSCF-SOCI method with the triple zeta plus triple polarization augmented with two sets of higher angular momentum functions and two sets of diffuse functions basis set [TZ3P(2f,2d)+2diff], the energy separation (T₀) between the ground (X˜ ¹A₁) and first excited (a˜ ³B₁) states is determined to be 20.5 kcal/mol (0.890eV,7180cm⁻¹), which is in excellent agreement with the experimental T₀ value of 21.0 kcal/mol (0.910eV,7340cm⁻¹). With the same method the T₀ value for the a˜ ¹B₁−X˜ ¹A₁ separation is predicted to be 45.1 kcal/mol (1.957 eV,15780 cm⁻¹), which is also in fine agreement with the experimental value of 44.4 kcal/mol (1.925 eV,15530 cm⁻¹). The T₀ value for the B˜ ¹A₁−X˜ ¹A₁ separation is determined to be 79.6 kcal/mol (3.452 eV,27 840 cm⁻¹). After comparison of theoretical and experimental T₀ values for the a˜ ³B₁ and a˜ ¹B₁ states and previous studies, error bars for the B˜ ¹A₁ state are estimated to be ±1.5 kcal/mol (±525 cm⁻¹). The predicted geometry of the B˜ ¹A₁ state is r_e(SiH)=1.458 and θ_e=162.3^∘. The physical properties including harmonic vibrational frequencies of the B˜ ¹A₁ state are newly determined. Received: 10 March 1997 / Accepted: 2 April 1997     

Regio and stereoselective synthesis of 1-methylseleno-1-vinyl and 1-phenylseleno-1-vinyl cyclopropanes

The Z and E teomers of the title compounds are regioselectivity and stereoselectively prepared respectively by reaction of phosphorus ylides with α-selenocyclopropyl aldehydes and by addition of α-lithio seleno-cyclopropanes on α-seleno aldehydes.