共查询到20条相似文献,搜索用时 31 毫秒
1.
Experimental data on conformational energies of the molecules FH2CHCCH2, FH2CFCCH2, FH2C(CH3)C&.dbnd;CH2 trans-FH2CHCC(CH3)H have been used to establish parameter values for the nonbonding atom ⋯ atom interaction F ⋯ C(sp2) within the Morse potential formulation. Torsional potentials have been calculated for the four molecules mentioned above and in addition for cis- and trans-FH2CHCCHF, (FH2C)2CCH2, cis-FH2CHCCHCH2F, CH3FCHHCCH2 and FH2CCH2HCCH2. Calculated results have been compared with experimental values. Torsional force constants for the molecules have been obtained. A comparison between fluoro, chloro and bromo compounds is presented. 相似文献
2.
The structural parameters of the completely relaxed 4–21G ab initio geometries of more than 30 basic organic compounds are compared to experimental results. Some ranges for systematic empirical corrections, which relate 4–21G bond distances to experimental parameters, are associated with total energy increments. In general, for the currently feasible comparisons, the following corrections can be given which relate calculated distances to experimental rg parameters and calculated angles to rs-structures For CC single bond distances, deviations between calculated and observed parameters (rg) are in the ranges of ?0.006(2) to ?0.010(2) Å for normal or unstrained hydrocarbons; ?0.011(3) to ?0.016(3) Å for cyclobutane type compounds; and +0.001(5) to +0.004(4) Å for CH3 conjugated with CO. For CO single bonds the ranges are ?0.006(9) to +0.002(3) Å for CO conjugated with CO; and ?0.019(3) to ?0.027(9) Å for aliphatic and ether compounds. A very large and exceptional discrepancy exists for the highly strained ethylene oxide, rs — re = ?0.049(5) Å and in CH3OCH3 and C2H5OCH3 the rs — re differences are ?0.029(5), ?0.040(10) and ?0.025(10) Å. Some of these discrepancies may also be due to deficiencies of the microwave substitution method caused by atomic coordinates close to inertial planes. For CN bonds, two types of NCH3 corrections are from +0.005(6) to ?0.006(6) and from ?0.009(2) to ?0.014(6) Å; and the range for NCO is +0.012(3) to +0.028(4) Å. For isolated CC double bonds the range is + 0.025(2) to +0.028(2) Å. For conjugated CC double bonds the correction is less positive (+0.014(1) Å for benzene). For CO double bonds the corrections are ?0.004(3) to +0.003(3) Å. For bond angles of type HCH, CCH, CCC, CCO, CCO, OCO, NCO and CCC the corrections are of the order of magnitude about 1–2° (or better). Angles centered at heteroatoms are less accurate than that, when hydrogen atoms are involved. Differences in HOC and NHC angles were found in a range of ?2.3(5)° to ?6.2(4)°. 相似文献
3.
《Journal of organometallic chemistry》1987,331(1):63-72
Bis(η-cyclopentadienyl)hydridorhenium Cp2ReH undergoes stereospecific trans insertion reactions when treated with monosubstituted acetylenes HCCR (R CO2Me, CN, CF3). The cis alkenyl complexes Cp2Re[η1-(Z)-CHCHR] thus formed isomerize thermally or under acid catalysis to produce the trans isomers Cp2Re[η1-(E)-CHCHR]. When Cp2ReH adds to HCCCOMe only the trans isomer is observed. The regiospecific β-addition of Cp2ReH contrasts with the α-addition of Cp2MoH2 and Cp2WH2. The insertion of acetylenes HCCR′ into the metalcarbon bond of some alkenyl complexes Cp2Re[η1-(E)-CHCHR] affords butadienyl complexes Cp2Re[η1-{(1E,3E)-CHCHR′CHCHR&}] (R,R′ COMe, CO2Me). The (E,E)-configuration of these compounds is deduced from 3J(13-C1H) coupling constants. 相似文献
4.
《Journal of organometallic chemistry》1987,323(3):371-384
The reactions of mononuclear carbene complexes of W and Fe of the type CO)mMC(OR)(CH2nCHCR′″ (M = FE, W; m = 4 and 5; n = 0, 2, 3; R′, R″ = C, CH3, OEt) with Fe(CO)5 have been studied. In all cases the reaction leads to new hetero (WFe) or homo (FeFe) μ-alkylidene complexes, the position of the double bond depending strongly on n. 相似文献
5.
《Journal of organometallic chemistry》1986,314(3):333-355
Bis-alkenyl complexes of the type (η-C5H5)2RH2(alkene − H)(alkyne + H) are obtained when the alkyne complex (η-C5H5)2Rh2(CO)(CF3C2CF3) is treated with the following alkenes: H2CCH2, H2CCHR (R = Me, But, Ph, CN), H2CCF2, RHCCHR′ (R = R′ = Me, Ph, Cl; R = Me, R′ = Et), cyclooctene and norbornene. An approximately equimolar amount of (η-C5H5)2Rh2(CO)2(CF3C2CF3) is also formed. The reactions are greatly accelerated when the reaction mixtures are exposed to sunlight. There is some regioselectivity in the reactions with H2CCHR and MeHCCHet, with a preference for CH bond cleavage at the least crowded alkene-carbon. When the reaction with acrylonitrile is performed in the absence of sunlight, the complex (η-C5H5)2(CO){(H2CCHCN)(CF3C2CF3)} can be isolated; upon exposure to sunlight, there is loss of CO and H-transfer to form two isomers of the appropriate bis-alkenyl complex.The molecular geometries of (η-C5H5)2Rh2(CHCHCN){C(CF3)C(CF3)H} and (η-C5H5)2Rh2(CHCF2){C(CF3)C(CF3)H} have been ascertained by X-ray structure determination. Each molecule has two bridging alkenyl units spanning a RhRh single bond; the dihedral angle between the two RhRhCC planes is just above 90°. There is a cyclopentadienyl ring η5-attached to each metal. Crystal data: C17H13F6NRh2·H2O, M 569.1, monoclinic, P21/n, a 15.014(7), b 14.882(7), c 8.590(5) Å, β 94.57(9)°, Z = 4, final R 0.056 for 2493 observed reflections; C16H12F8Rh2, M 562.1, monoclinic, P21/c, a 13.037(6), b 8.765(2), c 14.873(3) Å, β 103.16(3)°, Z = 4, final R 0.062 for 1820 observed reflections. 相似文献
6.
Microwave studies (26.5–40 GHz) of further isotopic species of selenoketene formed by pyrolysis of 1,2,3-selenodiazole (12CH212C76,77,82Se, 12CH213C80Se and 13CH212C80Se) and by pyrolysis of 5-deuterio-1,2,3-selenodiazole (12CHD12C78,80Se) are reported. In conjunction with earlier results for 12CH12C78,80Se an rs structure has been derived with distances SeC (1.706 Å), CC (1.303 Å), CH (1.0908 A) and a HCH bond angle of 119.7°. The geometry of the CH2C moiety of selenoketene is closer to allene, CH2CCH2, than to ketene, CH2CO. 相似文献
7.
J. Kuyper L.G. Hubert-Pfalzgraf P.C. Keijzer K. Vrieze 《Journal of organometallic chemistry》1976,108(2):271-280
The preparation and properties are described of trans-[(Ph3P)2(CO)M(RNSNR)] [ClO4] (M RhI, IrI; R Me, Et, i-Pr, t-Bu) and of cis- or trans-[L2Pt(RNSNR)X] [ClO4] (X Cl?, L Et2S, PhMe2As, PhMe2P, R Me, t-Bu; X CH3, L PhMe2P, R Me).1H and 13C NMR data show the existence of various isomers in solution which may interconvert via intra- and inter-molecular exchange processes. A general reaction scheme for the intramolecular exchange processes is discussed. 相似文献
8.
Ethyl but-3-ynoate undergoes electrophilic additions of BrCl and of ICl to give CHXCClCH2COOEt E (X = Br or I). The addition of sulfenyl halides RSY follows the opposite orientation and leads to CHYCSRCH2COOEt E (Y = Cl or Br, R = Et or Ph). In the case of IBr, both CHICBrCH2COOEt E and CHBrClCH2;COOEt E are obtained.A mechanistic interprétation of these results is supported by both the orientation and the kinetic order of the addition: PhSCl reacts by an AdE2 process, whereas ICl addition involves a combination of AdE3 and AdE4 mechanisms. 相似文献
9.
A. Katrib T.P. Debies R.J. Colton T.H. Lee J.W. Rabalais 《Chemical physics letters》1973,22(1):196-200
A criterion for spectral assignments employing the variation in the differential photoionization cross section as a function of the incident photon energy is described. The He I and He II photoelectron spectra of N2, CO, CH3SH, ClHCCHCH3, H2CCBrCH3, and transClHCCHCl are presented and discussed in terms of this criterion. 相似文献
10.
The molecular structure of vinyldimethylchlorosilane has been determined by gas phase electron diffraction at room temperature. The least squares values of the bond lengths (rg) and bond angles (∠α) are : r(CH) = 1.086(6) Å, r(CC) = 1.347(5) Å, r(SiC=) = 1.838(6) Å, r(SiC) = 1.876(3) Å, r(SiCl) = 2.078(2) Å, ∠CCSi = 127.8° (1.2) and ∠=CSiCl = 107° (1). Models with pure syn form and a mixture of syn and gauche gave equally good agreement with the diffraction data. 相似文献
11.
《Journal of organometallic chemistry》1986,306(2):167-182
17O, 29Si, and 13C NMR spectra of more than 100 mono-, di-, tri- and tetra-alkoxysilanes R4−nSi(OR′)n; R = CnH2n+1, Ph, CH2Cl, CH2Br; R′ = CnH2n+1, CH2Ph, CH2CH2Cl, CH2CHCH2, CH2CCH, CH2CF3. (CH2)3Cl, (CH2)3CN have been studied.Linear relationships between the chemical shifts of 17O, 29Si, 13C in alkoxysilanes and the inductive and steric constants of substituents R and R′ were observed. Different transmission of electronic effects along the SiO bond in various directions was revealed by means of 13C, 29Si, 17O NMR spectroscopy and correlation analysis. The results are discussed in terms of (pd)π-bonding between the oxygen and silicon atoms in compounds containing an SiO bond. 相似文献
12.
N-Lithiomethanesulfinicacidimide amides of the general composition MeS(NR)NRLi (II) are prepared by addition of methyllithium to sulfur diimides RNSNR (I) (R t-Bu or SiMe3. The corresponding reaction with Me3SnNSNSnMe3 yields the N-lithio salt (Me3SnNSN)Li (III) and tetramethylstannane; addition compounds are not formed. Methatetical reactions of II with chlorostannanes, Me3SnCl or Me2SnCl2, leads to the formation of the sulfinicacidimideamidostannanes MeS(NR)NRSnMe3 (IV) and MeS(NR)NRSnClMe2 (Va), respectively. 相似文献
13.
Terminally unsaturated dimers and co-dimers of vinyl monomers having the general formula CH2CCCR were synthesized, where X = Y or X ≠ Y, X and Y being COO R or CN groups, RCH3 or H. NMR and base catalyzed isomerization of the 1-olefins prepared is discussed. 相似文献
14.
Novel η1-vinyl complexes of the type Cp(CO)(L)FeC(OMe)C(R)R′ (R = R′ = H, Me; R = H, R′ = Me; L = Me3P, Ph3P) are obtainied via methylation of the acyl complexes Cp(CO)(L)FeC(O)R (R = Me, Et, i-Pr) with MeOSO2F and subsequent deprotonation of the resulting carbene complexes [Cp(CO)(L)FeC(OMe)R]SO3F with the phosphorus ylide Me3PCH2. The same procedure can be applied for the synthesis of the pentamethylcyclopentadienyl derivative C5Me5(CO)(Me3P)FeC(OMe)CH2, while treatment of the hydroxy or siloxy carbene complexes [Cp(CO)(L)FeC(OR)Me]X (R = H, Me3Si; X = SO3CF3) with Me3CH2 results in the transfer of the oxygen bound electrophile to the ylidic carbon. Some remarkable spectroscopic properties of the new complexes are reported. 相似文献
15.
The 13P and 13C spectra of the triply 13C labelled molecules (CH3)3P, (CH3)3PO, (CH3)3PS and (CH3)3PSe oriented in a nematic phase are reported. The CPC bond angles have been measured. The 13P chemical shift tensor shows a large anisotropy except in the case of (CH3)3P. The abnormal large value observed for the PSe bond length suggests a large anisotropy of the 1J(PSe) spin coupling. 相似文献
16.
The enthalpy of the reaction: Pt(PPh3)2 (CH2CH2)(cryst.) + C(CN)2C(CN)2 (g) → Pt(PPh3)2 {C(CN)2C(CN)2}(cryst.) + CH2 CH2 (g) has been determined as ΔH298=?155.8±8.0 kJ·mol?1, from solution calorimetry. The interpretation, that the platinumethylene bond is much weaker than the platinumtetracyanoethylene bond, is contrary to conclusions drawn recently from electron emission spectroscopic studies, but in agreement with available structural data. 相似文献
17.
The crystal structure of Ph3SnNCS has been determined by single crystal X-ray diffraction. The crystals are monoclinic, P21, a = 19.02(3), b = 11.67(2), c = 15.49(2)Å;, β = 95.64(10)°, Z = 8. The molecules are arranged in infinite zig-zag S…SnNCS…Sn&.sbnd; chains similar to those in Me3SnNCS, but with slightly longer SnN, shorter SnS bonds, and almost planar SnC3 units. Principal mean bond lengths and angles are: SnN, 2.22(5); NC, 1.17(8); CS, 1.58(7); SSn, 2.92(1); SnC, 2.09(3); CC, 1.38(2)Å; SnNCm 161(4); CSSn, 97(3); SSnN, 175(3) and CSnC, 119.8(1.5)°. 相似文献
18.
The structures of bis(lithium-N,N,N′,N′-tetramethylethylenediamine) (all-trans-1,5,9-cyclododecatrienenickel) (I) and tris(N,N,N′,N′,-tetramethyl-2-butene-1,4-diamine)dilithiumnickel (II) have been determined from single cyrstal X-ray data measured by counter methods. Crystals of I belong to the orthorhombic space group Pbca with a 13.776(2), b 14.090(2), c 58.374(6) », Z = 16 and dc 1.10 g cm-3. Compound II crystallizes in the monoclinic space group C2/c with a 22.960(2), b 8.9860(3), c 15.1984(6) », β 109.015(5)°, Z = 4 and dc 1.12 g cm-3. Refinement of I (II) coverged with R = 0.097 (0.037) for the 4281 (2424) reflections with I > 2σ(I).Two unique and essentially identical molecules not having crystallographic symmetry were found for I while molecules of II possess crystallographic C2 symmetry, the two fold axis passing through the Ni atom and bisecting one olefinic CC bond. The trigonal bipyramidal geometry of the Ni atoms, the centers of three olefinic double bonds in the trigonal plane and Li atoms in apical positions, is distorted in I but nearly exact in II. The NiC (olefinic) bond lengths average 1.99(3) and 2.000(3) » in I and II respectively. The shorter bond distances to the Ni a toms formed by the three-coordinate Li atoms in I, average 2.400(6) », compared to those formed by the four-coordinate Li atoms in II, 2.561(3) », may be due to Ni → Li dπ → pπ backbonding in I. The LiNiLi angles are (average) 164(2)° in I and 178.9(1)° in II. The strength of the Ni olefin interactions in these compounds is most clearly shown by the long mean CC distances (1.452(9) ») and 40(2)° bending back of the olefinic substituents from the Ni atom in II. 相似文献
19.
Wolfgang A. Herrmann Cornelia Weber Manfred L. Ziegler Orhan Serhadli 《Journal of organometallic chemistry》1985,297(2):245-254
The diazoolefines of composition N2CCR2 (R/R = CH3/CH3 and(-CH2-)5) are suitable precursors of the corresponding vinylidene ligands CCR2. Thus, treatment of the RhRh complex [(η5-C5Me5)Rh(μ-CO)]2 (1) with the N-nitrosourethanes 2a and 2b, resp., in the presence of lithium t-butoxide yields the otherwise inaccessible μ-vinylidene complexes (μ-CCR2)[(η5-C5Me5)Rh(CO)]2 (R = CH3 (3a), R,R = (-CH2-)5 (3b)). The analogous cobalt compound (μ-CCMe2)[(η5-C5Me5)Co(CO)]2 (5a) is obtained similarly. This procedure extends the well-documented diazoalkane method for the synthesis of μ-alkylidene complexes to the less stable diazoalkenes. A single-crystal X-ray diffraction study of the dimethylvinylidene derivative 3a shows the CMe2 ligand to adopt an almost symmetrically metal-bridging position (d(RhC) 197.8(1) and 204.3(1) pm), with a rhodium-rhodium single bond completing a three-membered Rh2C-metallacycle (d(RhRh) 268.4(0) pm) analogous with cyclopropane. 相似文献
20.
Takao Ikariya Yasutoshi Ishikawa Kiyomiki Hirai Sadao Yoshikawa 《Journal of organometallic chemistry》1985,288(3):311-315
The reaction of WCl6/LiAlH4 with imines, R′NCHR, gave tertiary amines, R′N(CH2R)2, and secondary amines, R′NHCHRCH2R. Isotope labeling experiments revealed that the reaction involved two types of azatungstenacyclobutanes, HR and HR, produced from the reaction of an alkylidene tungsten intermediate with the imine CN double bond. Formation of these metallacyclobutanes is highly dependent on the solvent used. 相似文献