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1.
The classical trajectory method has been used to investigate product-state symmetry in the three-body direct photofragmentation of Cd(CH3)2. Photon absorption was assumed to satisfy the Franck principle and relative weights for trajectory initial conditions were assigned by either the Wigner or the classical (300 K) distribution function. In qualitative agreement with earlier “quasi-classical” sampling studies of Kellman et al. for photolysis of the Cd(CH3)2 vibrational ground state, product-state asymmetry is found to increase with increasing photolysis wavelength. Contrary to the “quasi-classical” sampling results, however, sampling with the classical distribution function indicates that product-state symmetry is unaffected by vibrational excitation of Cd(CH3)2 prior to photolysis. For sampling with the Wigner distribution function, in agreement with the “quasi-classical” sampling studies, excitation of the Cd(CH3)2 asymmetric stretch prior to photolysis is found to increase product-state asymmetry.  相似文献   

2.
A new analysis of the microwave spectra of methyl isocyanide CH314NC in the v8 and 2v8 states is obtained by the use of more experimental data and calculations by diagonalization of the energy matrix. The same spectra for the 15N derivative have been observed, and their analysis reveals resonant effects still stronger than for CH314NC. Sets of rotation and rotation-vibration constants are reported for both molecules.  相似文献   

3.
Inefficient vibrational energy exchange between the lowest vibrational mode and the higher lying vibrational modes of CH2Cl2, CD2Cl2, CH2ClBr and CH2Br2 was investigated by ultrasonic absorption experiments. Breathing sphere theory is used to interpret the data available for VV and VR, T transfer in methylene halides.  相似文献   

4.
35Cl NQR spectra of dichlorophosphates Me(PO2Cl2)2 · 2D (Me = Mg, Ca, Mn; D = CH3COOC2H5, CH3COCH3, POCl3) are studied in the temperature range 77 ? T (K) ? 305. It is shown that the three compounds with CH3COOC2H5 as donor are isomorphic at 77 K, the crystal structure of Mn(PO2Cl2)2· 2CH3COOC2H5. The structure of Mg(PO2Cl2)2?· 2CH3COCH3 and of Mg(PO2Cl2)2 · 2POCl3 probably consists of infinite chains as found for Mn(PO2Cl2)2· 2CH3COOC2H5. Mg(PO2Cl2)2· 2CH3COOC2H5 shows phase transformations and a complicated dynamical behaviour leading to strong deviations from a Bayertype NQR function v = f(T). The donor capacity of POCl3 in Mg(PO2Cl2)2· 2POCl3 is comparable with the donor strength in AsCl3 · POCl3 · A dπ-pπ overlap of the P-O bond influences the P-Cl bond.  相似文献   

5.
An X-ray structure analysis for the title complex obtained by the reaction of PtIICL2(C5H4NC(O)C?H+NC5H3(CH3)2-3.5) with ethylenediamine in water has revealed the presence of an ylide carbon atom which is coordinated to the platinum(II) ion with an sp2 configuration.  相似文献   

6.
A set of phosphine complexes of the type W(CO)3(PX3)2(CH2CH2) (X=H, CH3, F, Cl, Br, and I) were investigated by density functional theory method (BP86) to examine the effect of the substituent X on the orientation of C-C vector of the ethylene ligand with respect to one of the metal-ligand bonds as well as the donation and the backdonation in the bonding ligands of phosphine and ethylene. When X=CH3, H, F, and Cl, the ethylene C-C vector prefers to be coplanar with metal-phosphine bonds, while for the ethylene complexes containing PBr3 and PI3 ligands, the structural preference is coplanarity of the ethylene and the metal-carbonyl bonds. The molecular orbital calculations and natural bond orbital analysis were used to examine the structural consequences derived from these complexes. It can be concluded that the structural preferences in the complexes have a clear relation to electronic effects of phosphine ligands. Our calculations for halide phosphine complexes, particularly for PBr3 and PI3, allow us to conclude that in addition to electronic effects, steric factors can also affect the orientation of the ethylene ligand in complexes.  相似文献   

7.
Triallyl- and diallyltin carboxylates [(CH2CHCH2)3SnOOCR′ with R′ = CH3 and CH2Cl, (CH2CHCH2)2Sn(OOCR′)2 with R′ = CH2Cl and CHCl2)] and tetraallyl-1,3-diacyloxydistannoxanes {[(CH2CHCH2)2SnOOCR′]2 with R′ = CH2Cl,CHCl2 and CCl3}, have been prepared from the reaction of tetraallytin with carboxylic acids in methanol.  相似文献   

8.
NQR spectra were observed for α-(CH3)2 TeX2 (X=Cl, Br, I) and (CH3)2 TeI4 at various temperatures. The two 81Br NQR lines were observed above 110 K in α-(CH3)2TeBr2. The characteristic temperature dependence of the 127I NQR line in α-(CH3)2 TeI. can be explained by the 3c—4e bond of the linear I---Te---I group. The positive temperatures dependence of the lowest 127I NQR line in (CH3)2TeI4 is discussed on the basis of the electron population calculated from Townes—Dailey treatment.  相似文献   

9.
1,2-Eliminations are a varied and extensive set of dissociations of ions in the gas phase. To understand better such dissociations, elimination of CH2=CH2 and CH3CH3 from (CH3)2NH+CH2CH3 (1) and of CH4 from (CH3)2NH2+ are characterized by quantum chemical calculations. Stretching of the CN bond to ethyl is followed by shift of an H from methyl to the bridging position in ethyl and then to N to reach (CH3)2NH2+ + CH2=CH2 from 1. CH3CH3 elimination by H-transfer to C2H5+ to form CH3NH+=CH2 + CH3CH3 also takes place. (CH3)2NH2+ eliminates methane by CN bond extension followed by β-H-transfer to give CH2=NH+ + CH4. Low-energy reactions resembling complex-mediated 1,2-eliminations occur and constitute a hitherto largely unrecognized type of reaction. As in many complex-mediated reactions, these reactions transfer H between incipient fragments. They are distinguished from complex-mediated processes by the fragments not being able to rotate freely relative to each other near the transition state for reaction, as they do in complexes. Most 1,2-eliminations are ion-neutral complex-mediated, occur by the just described lower energy reactions, have 1,1-like transition states, or utilize highly asynchronous 1,2 transition states. All of these avoid synchronized 1,2-transition states that would violate conservation of orbital symmetry.  相似文献   

10.
The enthalpy of the reaction: Pt(PPh3)2 (CH2CH2)(cryst.) + C(CN)2C(CN)2 (g) → Pt(PPh3)2 {C(CN)2C(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 platinumethylene bond is much weaker than the platinumtetracyanoethylene bond, is contrary to conclusions drawn recently from electron emission spectroscopic studies, but in agreement with available structural data.  相似文献   

11.
The crystal and molecular structure of the complex Th[η5-(CH3)5C5]2[CH2-Si(CH3)3]2, which undergoes facile intramolecular cyclometalation to the thoracyclobutane Th[η5-(CH3)5C5]2(CH2)2Si(CH3)2, is reported. While the Th[η5-(CH3)5C5]2 ligation is unexceptional, the Th[CH2Si(CH3)3]2 fragment is highly unsymmetrical having Th-C (corresponding angle Th-C-Si) 2.51(1) Å (132.0(6)°) and 2.46(1) Å (148.0(7)°). This conformation, which appears to result from severe intramolecular non-bonded contacts, allows a methyl hydrogen atom of one CH2Si(CH3)3 ligand to approach within ca. 2.3 Å of the α-carbon atom of the other CH2Si(CH3)3 ligand.  相似文献   

12.
A Bayard-Alpert (BA) gauge was used to determine apparent relative sensitivites Srel,X for O2, N2O, NO, NO2, NH3, CClF3 and CH3OH from gauge calibration measurements in the range 1.3×10–1 Pap1.3·10–3Pa. Nitrogen was used as a calibration standard.  相似文献   

13.
The reactions of CH3O2 with SO2 and NO have been studied by steady state photolysis of azomethane in the presence of O2SO2→NO mixtures at 296 K and 1 atm total pressure. The quantum yield of NO oxidation by CH3O2 radicals is increased substantially when SO2 is added to the system indicating an SO2 induced chain oxidation of NO. The rate law gives k1/k2 = (2.5 ± 0.5) × 10?3 for CH3O2 + SO2 → CH3O2SO2 (1), CH3O2 + NO → CH3O + NO2 (2). Combining this ratio with the absolute value of k1 = 8.2 × 10?15 cm3 s?1 gives k2 = 10?11.5 ± 02 cm3 s?1.  相似文献   

14.
(CpCH_2CH_2CH = CH_2)_2MCl_2(M=Zr, Hf)/MAO and Cp_2ZrCl_2/MAO (Cp=cyclopentadienyl; MAO=methylaluminoxane) catalyst systems have been compared for ethylene copolymerization to investigate the influence of theligand and transition metal on the polymerization activity and copolymer properties. For both CH_2CH_2CH=CH_2 substitutedcatalysts the catalytic activity decreased with increasing propene concentration in the feed. The activity of the hafnocenecatalyst was 6~8 times lower than that of the analogous zirconocene catalyst, ~(13)C NMR analysis showed that the copolymerobtained using the unsubstituted catalyst Cp_2ZrCl_2 has greater incorporatien of propene than those produced byCH_2CH_2CH=CH_2 substituted Zr and Hf catalysts. The melting point, crystallinity and the viscosity-average molecularweight of the copolymer decreased with an increase of propenc concentration in the feed. Both CH_2CH_2CH= CH_2 substitutedZr and Hf catalysts exhibit little or no difference in the melting point and crystallinity of the produced copolymers. However,there are significant differences between the two zirconocene catalysts. The copolymer produced by Cp_2ZrCl_2 catalyst havemuch lower T_m and X_c than those obtained with the (CpCH_2CH_2CH=CH_2)_2ZrCl_2 catalyst. The density and molecular weightof the copolymer decreased in the order: (CpCH_2CH_2CH=CH_2)_2HfCl_2>(CpCH_2CH_2CH=CH_2)_2ZrCl_2>Cp_2ZrCl_2. The kineticbehavior of copolymerizaton with Hf catalyst was found to be different from that with Zr catalyst.  相似文献   

15.
Reaction of lithiated bis(diphenylphosphino)amine, [(C6H5)2P]2N? Li+, with K2PtCl4 or PdCl2 (in the presence of trimethylphosphine) yields the homoleptic bis[bis(diphenylphosphino)amide] complexes I and II, respectively. With NiCl2/(CH3)3P the chloro-bridged dinuclear complex III is obtained. A symmetrical bonding of the Ph2P-·N-·PPh2 anion to the metal through the phosphorus atoms is indicated for these diamagnetic, deep-yellow (I, II) or red (III) complexes by 31P NMR spectroscopy (J(PtP) 1812 Hz for I). I and II are dissolved in CF3COOH with protonation at the nitrogen atoms to give bis(diphenylphosphino)amine complexes IV and V, respectively (J(PtP) 2080 Hz for IV). IV and V are 1:2 electrolytes in CH3NO2. Methylation of I-III with CH3OSO2F leads to the bis(diphenylphos-phino)methylamine complexes VI-VIII, of which the palladium compound VII has been structurally characterized by single crystal X-ray diffraction. VII contains a planar CNP2PdP2NC skeleton and is thus based on planar ligand arrays both at Pd and at the two N atoms.  相似文献   

16.
The [PdCl2(NH2(CH2)5CH3)2] complex was tested as catalyst for 1-heptyne semihydrogenation under mild conditions of temperature and pressure in homogeneous and heterogeneous systems. Species were characterized by XPS and FTIR techniques. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

17.
The thermal decompositon of a number of organo-bielemental vanadium compounds with the general formula Cp2V(ER3) (ER3 - GeEt3, SnEt3, CH2SiMe3, SeGeEt3) has been investigated in solids and in solution. The main decomposition products of Cp2V(SnEt3) are vanadocene and hexaethyldistannane. Et3GeH, Et3GeCp, Cp2V and CpV(C5H4GeEt3) are formed from Cp2V (GeET3) decomposition. Isolated CpV(C5H4GeEt3) is characterized by IR and mass spectra. The decomposition of Cp2V(CH2SiMe3) is accompanied by Me4Si, Cp2V and CpV-(C5H4CH2SiMe3) formation, the latter is identified from the mass spectrum. Triethylgermane, vanadocene, and a diselenide of vanadium are isolated on decomposition of Cp2V(SeGeEt3). Based upon the experimental data, mechanisms for the decompositon are proposed.  相似文献   

18.
Novel half-sandwich [C9H5(SiMe3)2]ZrCl3 (3) and sandwich [C9H5(SiMe3)2](C5Me4R)ZrCl2 (R = CH3 (1), CH2CH2NMe2 (2)) complexes were prepared and characterized. The reduction of 2 by Mg in THF lead to (η5-C9H5(SiMe3)2)[η52(C,N)-C5Me4CH2CH2N(Me)CH2]ZrH (7). The structure of 7 was proved by NMR spectroscopy data. Hydrolysis of 2 resulted in the binuclear complex ([C5Me4CH2CH2NMe2]ZrCl2)2O (6). The crystal structures of 1 and 6 were established by X-ray diffraction analysis.  相似文献   

19.
By measuring the relative CO quantum yields from ketene photolysis as a function of photolysis wavelength we have determined the threshold energy at 25° for CH2CO(1A1) → CH2(3B1) + CO(1Σ+) to be 75.7 ± 1.0 kcal/mole. This corresponds to a value of 90.7 ± 1.0 kcal/mole for ΔHf2980[CH2(3B1)]. By measuring the relative ratio of CH2(1A1)/CH2(3B1) from ketene photolysis as a function of photolysis wavelength we have determined the threshold energy at 25°C for CH2CO(1A1) → CH2(1A1) + CO(1Σ+) to be 84.0 ± 0.6 kcal/mole. This corresponds to a value of 99.0 ± 0.6 kcal/mole for ΔHf2980[CH2(1A1)]. Thus a value for the CH2(3B1) ? CH2(1A1) energy splitting of 8.3 ± 1 kcal/mole is determined, which agrees with three other recent independent experimental estimates and the most recent quantum theoretical calculations.  相似文献   

20.
The salt, [N(CH3)4][IO2F2], was prepared from [N(CH3)4][IO3] and 49% aqueous HF, and characterized by Raman, infrared, and 19F NMR spectroscopy. Crystals of [N(CH3)4]2[IO2F2][HF2] were obtained by reduction of [N(CH3)4][cis-IO2F4] in the presence of [N(CH3)4][F] in CH3CN solvent and were characterized by Raman spectroscopy and single-crystal X-ray diffraction: C2/m, a = 14.6765(2) Å, b = 8.60490(10) Å, c = 13.9572(2) Å, β = 120.2040(10)°, V = 1523.35(3) Å3, Z = 4 and R = 0.0192 at 210 K. The crystal structure consists of two IO2F2 anions that are symmetrically bridged by two HF2 anions, forming a [F2O2I(FHF)2IO2F2]4− dimer. The symmetric bridging coordination for the HF2 anion in this structure represents a new bonding modality for the bifluoride anion.  相似文献   

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