摘要:

AbstractDecarbonylation of triosmium methylthiolato cluster Os3(CO)10(μ‐H)(μ‐SMe) with Me3NO in acetonitrile solution gave cluster Os3(CO)9(NCMe)(μ‐H)(μ‐SMe) (1), in which one axial CO on the non‐bridged Os atom is replaced by an acetonitrile ligand. Crystal data for2: space group P bca, a = 14.491(1), b = 16.107(5), c = 16.639(5) Å, Z = 8; RF= 0.037, Rw= 0.033. Treatment of2with CpW(CO)3H in refluxing THF solution yielded two cluster compounds with formula CpWOs3(CO)11(μ‐H)2(μ3‐SMe) (2) and CpWOs3(CO)11(μ‐H)2(μ‐SMe) (3) as the principle products. The first possesses a spiked‐triangular geometry with a triply bridging thiolato ligand and the second adopts a butterfly metal core arrangement with an edge‐bridging thiolato grouping. The structure of 2 was characterized by single‐crystal X‐ray diffraction. Crystal data: space group P 1, a = 8.865(5), b = 8.959(3), c = 16.688(4) Å, α = 103.49(2), β = 93–58(3), γ =

ISSN:0009-4536    

DOI:10.1002/jccs.199400086

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractAerial dehydrogenation of the Iigand in (C‐meso‐3,5,7,7,10,12,14,14‐octamethyl‐1,4,8,11‐tetraazacyclotetradeca‐4, 11‐diene)cobalt(III) leads to yellow chunky crystals oftrans‐diaqua(C‐meso‐3,5,7,7,10,12,14,14‐octamcthyl‐1,4,8,11‐tetraazacyclotetradeca‐1,4,8,11‐tetraene)cobait(II)(1). The crystal structure of this complex was determined by xray crystallography and a mechanism

ISSN:0009-4536    

DOI:10.1002/jccs.199400087

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractSemiempirical calculations of activation energies confirm the importance of orbital overlap effect on thermal reverse homo‐Diels‐Alder reactions and intramolecular reverse ene reactions. Computations of the transition states of cis‐3,6‐dimethyl‐3,6‐dihdropyridazine, 2,5‐dimethyl‐3,4‐diaza bicyclo[4.1.0]hept‐3‐ene, 2,5‐dimethyl‐3,4‐diaza bicyclo[4.2.0]oct‐3‐ene and (cis‐2(S)‐(2(S)‐isopropyl‐1‐d3)‐1(S)‐(1(E)‐propenyl‐2‐d)cyclopropane indicate that activation energies are considerably decreased when optimal overlap is accomplished. The orbital overlap effect overcomes the steric effect in intramolecular reverse ene reaction of compounds such as (cis‐3‐R‐2(S)‐(2(S)‐isopropyl‐1‐d3)‐1(S)‐(1(E)‐pr

ISSN:0009-4536    

DOI:10.1002/jccs.199400088

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractBridging a Ge atom across the two C‐C bonds in C60was treated according to the PM3 method. The C2v(6/6) closed isomer represents the ground state of the system, located 52 kJ/mol below the C5(5/6) closed structure and 97 kJ/mol below the C5(5/6) open structure. However, at high temperatures the closed 5/6 isomer becomes the most stable, whereas the ground‐state structure is the least populated component under conditions of thermodynamic equilibrium, although no isomer is negligible. The applicable characteristics indicate a reasonable absolute stability of the whole sys

ISSN:0009-4536    

DOI:10.1002/jccs.199400089

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractAnalysis of measurements of vibration‐rotational transitions of209Bi1H and209Bi2H in electronic ground state × 0+yielded values of coefficients of radial functions that represent the intemuclear potential energy and adiabatic and nonadiabatic rotational effects of the hydrogen atomic centre. Both these effects have exceptionally large magnitudes, tentatively attributed in part to interaction with nearby electronically excited state A 1. The maximum range of validity of radial functions of BiH is 1.49 ≤ R/10−10m ≤ 2.4; the equilibrium intemuclear distance Reis (1.8041955 ± 0.00000186)

ISSN:0009-4536    

DOI:10.1002/jccs.199400090

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe rate coefficient of the reaction of OH with CF3CH2F at six temperatures in the range 255‐424 K was determined by means of the discharge‐flow/resonance‐fluorescence technique. The resonance fluorescence of OH, excited by emission from a gaseous mixture of H2O and He subjected to a microwave discharge, was detected by photon‐counting technique. The reaction was carried out under pseudo‐first‐order conditions with [CF3CH2F]>>[OH]; the rate coefficient was determined to be k = (3.9±0.6) × 10−15cm3molecule−1s−1at 298 K; the uncertainty represents the 95% confidence limit. The temperature dependence of the rate coefficient is expressed in the Arrhenius form, k(T) = (9.9±1.0) × 10−13exp [‐(164

ISSN:0009-4536    

DOI:10.1002/jccs.199400091

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractIn a batch‐stirred experiment, the Mn(II)‐catalyzed reaction of bromate ion with methyl‐, ethyl‐ or n‐butyl‐malonic acid (MeMA, EtMA or BuMA) exhibits oscillating behavior similar to the prototype Ce(III)‐catalyzed Belousov‐Zhabotinsky (BZ) reaction with malonic acid (MA). The effects of manganese ion, bromate ion, organic substrate, sulfuric acid, and chloride ion on the oscillating pattern were investigated. Both conventional and stopped‐flow spectrophotometric methods were applied to study the kinetics of reactions of Mn(III) ion with MA, MeMA, EtMA, BuMA, bromomalonic acid (BrMA), and dibromomalonic acid (Br2MA). The order of reactivity toward Mn(III) oxidation is MA>BrMA>MeMA>Br2MA>(EtMA, BuMA). The experimental results

ISSN:0009-4536    

DOI:10.1002/jccs.199400092

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe bonding in a triatomic molecule XNP and its isomer NPX with X = H+CH3+, O and F+was investigated withab initiomolecular orbital calculation using a 6‐31G** basis set at Hartree‐Fock and MP4(sdtq) level. The bonding comparison is based on interaction between NP and X for the two structures. The result that NPX is less stable than XNP is rationalized according to greater promotion energy required for the lone pair of phosphorus in NP to form the P‐X bond than for that of nitrogen to form the N‐X bond. This a energy contribution is counterbalanced by the π energy contribution to a varying extent depend

ISSN:0009-4536    

DOI:10.1002/jccs.199400093

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractMonte‐carlo simulations of modified Eley‐Rideal mechanisms (ER) possessing decay and enhanced sticking probability and a three‐step catalytic reaction (TCR) over fractal surfaces were performed to examine the morphological effect on these surface reactions. Effects of decay and enhancing profiles on the reaction probability distribution (RPD) for the ER reaction and effects of varying probability of reaction steps and cluster sizes on the normalized selectivity distribution (NSD) for TCR were men analyzed with multifractal scaling techniques. For the ER mechanism, RPD tends to be uniform for rapid decay and relatively concentrated at greater enhancing rate. For TCR, increased cluster size is found to decrease the position sensitivity of NSD. A large ratio of dimerization to isomerization increases the position distinction among active sites when the adsorption probability equals to unity. At small p1,i.e., adsorption probability « 1, the ratio of dimerization to isomerization causes no effect on t

ISSN:0009-4536    

DOI:10.1002/jccs.199400094

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe distribution of deformation density of 2,5‐dimethyl thiathiophthene and 2,4‐diphenyl thiathiophthene are calculated via density functional method. The results are in good agreement with the corresponding experimental and theoretical distributions from an ab initio method. The ionization potentials obtained in this calculation on 2,5‐dimethyl thiathiophthene are in good agreement with those obtained experimentally from photoelectron spectroscopy, it is in better agreement than those VIPs based on ab initio calculations. Net atomic charges are compared with the experimental multipole refinement and with those calculated with ab initio and DFT methods for various atomic parti

ISSN:0009-4536    

DOI:10.1002/jccs.199400095

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY