物理化學學報(Wuli Huaxue Xuebao)DecemberActa Phys. -Chim. Sin, 2008, 24(12):2229- -22352229[Article]www. whxb.pku.edu.cn二氯乙烯鍺烯與甲硫醛環(huán)加成的反應(yīng)機理陳新12李瑛1.*(四川大學化學學院，成都610064; 2 皖西學院化生系,安徽六安237000)摘要:利用 MP2/6-311+G*方法計算了單線態(tài)二氯乙烯鍺烯與甲硫醛的各種反應(yīng)機理.計算結(jié)果表明兩者之間的環(huán)加成反應(yīng)具有很好的選擇性,優(yōu)勢反應(yīng)路徑分為三步:首先兩種反應(yīng)物經(jīng)過無能壘的放熱反應(yīng)形成中間體INT,然后INT經(jīng)歷過渡態(tài)TS3異構(gòu)化為P31,最后P31繼續(xù)與甲硫醛反應(yīng)形成二環(huán)雜環(huán)化合物P33.其中第一步反應(yīng)放熱103.4 kJ.mol",后兩步反應(yīng)能壘分別為0.7和32.3 kJ.mol-".關(guān)鍵詞:二氯乙烯鍺烯， 硫醛; 反應(yīng)機理; 選擇性中圖分類號: 0641Cycloaddition Reaction Mechanism between DichloromethyleneGermylene and MethanethialCHEN Xinl2LI Ying'('College of Chemistry, Sichuan University, Chengdu 610064, P. R. China;2Department of Chemistry and Life Sciences, West Anhui University, Lu'an 237000, Anhui Province, P. R. China)Abstract: Theoretical calculations at MP2/6-311+G * level were employed to investigate various reaction mechanismsbetween singlet dichloromethylene germylene and methanethial. Calculation results indicate that the dominant reactionpathway for this reaction consists of three steps. The two reactants itally form an intermediate INT through a barrier-free exothermic reaction of 103.4 kJ●mol-'. This intermediate then isomerizes to P31 via a transition state TS3 with anenergy barrier of 0.7 kJ. mol-. P31 finally reacts with methinethial to form the germanic heteropolycyclic product P33with an energy barrier of 32.3 kJ *mol-. This cycloaddition reaction thus has excellent selectivity.Key Words: Dichloromethylene germylene; Methanethial; Reaction mechanism; SelectivityRecently, much attention has been directed toward germylenesactions with olefins and acetylenes, respectivelyl18.19. Unfortu-from both experimental and theoretical aspectsl1-131. Generally,nately, the mechanistic basis of germylene chemistry is stillgermylene is a kind of quite unstable active intermediate.poorly understood, and it makes many germylene reactions un-Germylene reactions have atracted considerable attention as anreliable for synthetic planning. Moreover, no estimates of the ab-effective method in the syntheses of new bonds and heterocyclicsolute activation energies of such additions are as yet availablecompounds with Gell-51. For example, one of the best- studiedfrom experiments. The calculations of reaction pathways fogermylenes, :GeC1241 , reacts with alkenes by an unknown mech-germylene cycloadditions and the location and identification ofanism to give a variety of organogermanium products, includingthe structures of the transition states is therefore of great theoret-an alkene-germylene copolymerlo. The same phenomenon can alsoical interest.be found in the addition reaction of germylenes to acetylenicAs heavier carbene analogues, germylenes can be classifiedderivatives, which usually leads to either dimers or polymersl!7.into two types, i.e. the saturated and the unsaturated, just likeOn the contrary, the three- membered-ring cyclopropane and cy-carbenes. From previous theoretical study results, it seems possi-clopropene are the primary products of the carbene addition re-ble to conclude that the reactions between saturated germylenesReceived: June 19, 2008; Revised: September 23, 2008; Published on Web: October 20, 2008.中國煤化工*Corresponding author. Email: qingjiang2002@ 163.com; Tel: +8628-854 18330.教育部重點項目(105142)和四川省青年科技基金(03SQ04)資助MHCNMH GC Editorial office of Acta Physico .Chimica Sinica.2230Acta Phys. -Chim. Sin., 2008Vol.24(:GeX2, X=H, F, C, Br) and alkenes undergo the weakly bound 1 Calculation methodsgermylene/alkene complex precursors, and that the π-complexB3LYP/6-31+ G' and MP2/6-311+ G* implemented in themight be observable in gas phase germylene alkene reactionmixtures at low temperaturel20. This phenomenon of germylenepoints along the reaction pathways, respectively. Full optimiza-aditions is different from that in the corresponding carbene ad-tions and frequency analyses were done for the stationary pointsditions, in which stable carbene/alkene complexes, in particularon the reaction profile. To explicitly establish the relevantcomplexes between :CCl2 and ethylene and tetramethylethylene,species, the intrinsic reaction coordinate (IRC) was also calculateddo not xistl1.2.for all the transition states appearing on the cycloaddition energyThere have been many theoretical studies on the reactionsurface profile. Relative energies were obtained through threemechanisms between unsaturated carbenes and alkenes,methods, namely B3LYP/6-31+G *//B3LYP/6-31+G*, MP2/6-des, and ketones, and the common first reaction step is the for-311++G** B3LYP/6-31+G*, and MP2/6-311+G*//MP2/6-311+G*,mation of the π-complex precursors between the reatants [2.24respectively. Because the MP2 theory is particularly importantfor reliable energy prediction for systems containing π→π° in-saturated carbenes(l. On the contrary, studies on the reactionteraction29-35, and the 6-311+G * basis set has been proven to bemechanisms of unsaturated germylenes (:Ge=CX2) are reallyreliable in describing similar systems as described in Ref. [36 -sparsePS-2]. Up to date, it is not well known whether the difference38], unless otherwise noted, the relative energies reported in theof reaction mechanisms between saturated carbenes and unsatu-text correspond to the MP2/6-311+G /MP2/6-311+G* level, in-rated carbenes are still true for germylenes. Futhermore, elec-cluding the zero-point energy correction. A scaling factor oftronic-donating and/or electronic-drawing conditions of sub-0.98041391 was used to correct the directly computed zero-pointstituent X may affect cycloaddition reactivity of :Ge= CX, theo-energies (ZPEs). All calculations were performed with the Gaus-retical study on this aspect would be helpful for practical syn-sian 98 suite of programs.thetic planning. Hence, the research on germylenes and germy-lene reactions has important theoretial and practial signif- 2 Results and discussioncances.2.1 Path 1On the basis of above considerations, theoretical study on theThe ground state energy of dichloromethylene germylene incycloaddition reaction mechanisms between unsaturated dichloro-singlet is 108.75 kJ *mol-' lower than that of triplet state accord-methylene germylenes and methanethial was carried out. In thising to calculation results, which means that the steady groundpaper, reaction mechanism between them was investigated andstate of dichloromethylene germylene is a singlet state. As ilus-analyzed in terms of three possible pathways of cycloadditiontrated above, Path 1 between dichloromethylene germylene (R1)reaction. All the involved reaction channels are as follows:and methanethial (R2) forms a three-membered ring product(P1).This reaction consists of two steps. The first one is a barrier-freeCl2exothermic reaction of -103.4 kJ *mol , giving an intermediatePath1 Cl2C-Ge:+H2C-s-→人G21(INT). Then INT isomerizes to Pl with a barrier of33.5 kJ *mol-,HzcC SsRvia transition state (TS1). The major geometrical parameters ofreactants (R1 and R2), intermediate (INT), transition state (TS1),Path2 Cl2C- =Ge:+H2C=S一H2C- -sCCl2P21product (PI) are given in Fig.1, and the potential energy surfacesR1R2are given in Fig.2. The energies are listed in Table 1. The uniqueCIGe=CCIP22imaginary frequency of the transition state TS1 is approximatelyH2Cs600i cm*, and IRC calculation of TS1 and further optimizationfor the primary IRC results confrm it connects INT and P1.Ge- nCCk2HGenP23 .The addition of a singlet germylene to methanethial involvesH2C- JsHC-ssimultaneous interactions of the vacant germylenic p orbital(LUMO) with the flled methanethial π orbital (HOMO) and ofCeCCh2P24the flled germylenic σ orbital (HOMO) with the vacant methanethialπ° orbital (LUMO). Although a singlet germylene is inherentlyPath3 Cl2C- -Ge: + H2C= = S一:Ge一 SP31both an electrphile and a nucleophile, its behavior here is deter-mined by the electron distribution in the transition state. This de-R:pends on whether the LUMOmta/ HOMOetuetin or HOMOyamylax/CIGe 7SP32 .LUMMmrtunehial interaction is stronger in this state. Moreover, ac-:GCH2cording to Hoffmann's work4), there are two possible routes foraddition of a germylene to methanethial as shown in Fig.1(a, b).Cl2CtHeH.cGP33The π approach in中國煤化工ith the P orbitalof the germyleneCl2C- 'CH2i YHCN M H Gf mtanethial,.No.12CHEN Xin et al. : Cycloaddition Reaction Mechanism between Dichloromethylene Germylene and Methanethial 223 1:110.1610.1737心0.1729-C11 C120.17240.17321 C12C20.19240.1937P130.1886 .R07.2(23.79 120.90.22980.22701 、0.2412H1。0.20484830.1945/53 20.2201115.60.1858Ge0.1088H01088 670.1122.2H22010C12R2INTTS1Fig.1 Optimized structures of involved species of Path 1 at MP2/6-311+G* levelbond length in nm and bond angle in degree; a: π approach, b: σ approachhas only one plane of symmetry, making this reaction symmetrytor-acceptor C1- -Ge bond continuously strengthens, until ulti-allowed. On the other hand, Fig. l(b) gives the most symmetricalmately the singlet C1- Ge bond forms. During the formationtransition state and has been called the σ approach (least mo-course of C1- -Ge bond, germylene rotates anticlockwise whiletion), because the σ orbital of the germylene impinges on themethanethial rotates around C1- -S bond to ensure σ lone-pairmethanethial π system. Hoffnimann40 has pointed out that the σelectrons of Ge atom contact fully with π * orbital of methanethial.approach in Fig.1(b) is“forbidden”in terms of the conservationAbove analyses reveal that Path 1 is a concerted and asyn-of orbital symmetry and is therefore expected to be high in ener-chronous [2+1] addition reaction, just like the reaction of the sin-gy. On this basis, the preferred approach should be the π ap-glet germylene addition to ethylenel回.proach in Fig.1(a), in which the flled π MO interacts with theBoth R1 and R2 are planar and in C, symmetry, but when theyempty p orbital of the germylene.form reactant complex INT, their structures generate dramaticalAt the beginning of Path 1, the vacant 4p orbital of elec-deformation. Upon formation of INT, bond length ofC=S intropositive Ge atom inserts into the π orbital ofC= S bond fromR1 increases from 0.1614 to 0.1711 nm and C=Ge in R2 in-the end of electronegative S atom, and a semi-cyclic intermedi-creases from 0.1858 to 0.1937 nm. At the same time, bondate complex forms along with π electron migrating into the va-length of twoC- -H bonds in R1 and two C- -CI bonds in R2 arecant 4p orbitals of Ge atom. Because there is strong bond- form-no longer equivalent, they decrease to different extent compareding tendency between σ lone-pair electron of germylene and anti-to those of R1 and R2. It is worth noting that four atoms of R1bond π° orbital ofC1 end of methanethial, the σπ * type dona-and four atoms of R2 are not at the same plane on formation ofINT, for dihedral angle of HIC1SH2 and CI1C2GeCl2 are158.1° and 178.7° respectively.Upon formation of P1 from INT, ria TS1, contrary to the .0一\P2INT24gradually decrease tendency of bond length ofC2- Ge, Cl- -Ge,231+R2-100and Ge- -S, bond length of C1- -S gradually increase from0.1711 to 0.1885 nm, and ultimately form a typical single bond.TS22INT33During this course, double bond C2= Ge, single bonds C1- -Ge鳥-200-e33and Ge- -S also form. PI is more similar to TS1 than INT bystructure, it is also confirmed by dihedral angle of C2GeSC1-250-(INT: -85.4°, TS1: -103.6°, PI: -111.3%), CI2C2GeS(INT:-300-5.5", TS1:-30.8*, P1: -60.79), CI1C2GeS (INT: -173.2%, TS1:174.0°, PI: 150.39).Fig.2 The potential energy surface for the cycloadditionAs seen in Fig中國煤化工n TSI and Plreactions between dichloromethylene germylene andis only 10.7 kJ 'n=asily convert tomethanethial at MP2/6-311+G ' /MP2/6-311+G " levelINT ria TS1. TheMHCNMHGible,anditmay.2232Acta Phys. -Chim. Sin., 2008Vol.24Table 1 Relative energies for the species obtained withmembered ring, bond length of C2- -S change most dramaticallydifferent theoretical methods(INT: 0.311, TS2: 0.272, P21: 0.184) while the others changeAE/(kJ'mol)only about 0.01-0.02 nm. Activation barrier of this reaction isSpeciesa13.7 kJ.mol-.R1+R20.0.0For the first pathway, P22 is formed through the isomerizationINt-85.610L.6-103.4of P21 via TS22, a chloride atom transforms from C2 atom toTS1-76.4-71.7-69germanium atom and C= Ge forms simultaniously, activationPl-77.5-80.3-80.6barrier of this reaction is 26.2 kJ. mol '. For the second pathway,TS2-78.5-84.8-89.7P23 is formed through the isomerization of P21 via TS23, a hy-P21-168.0-202.4- -202.2drogen atom transforms from C1 atom to germanium atom andTS22 .-151.8-176.2-176.0C=Ge forms simutaniously, activation barrier of this reaction isP22-239.5-242.9- -242.5184.6 kJ . mol-. Because of high activation barrier for formationTS23-12.1-25.7-17.6of P23, it is quite difficult to obtain hydrogen transfer productP23-46.2 .-59.6-60.P23 at room temperature. Quite short separation between H andTS3-81.4-101.6-102.7C1 (0.1088 and 0.1092 nm, respectively) and long separation be-P31tween CI and Ge (0.2037 nm) in P21 make it quite difcult forTS32-217.4-188.8-192.6H to transfer from C1 to Ge. Step D and step E in Fig.2 andP3-247.9. -257.6-260.2Table 2 compete with each other with an energy barrier differ-P21+R2ence of 158.4 kJ *mol", and the ltter is much easier to takeINT24-38.1 .41.6place than the former. In other words, CI transfer is much easierTS24-18.4-15.2-14.5than H transfer for the between dichloromethylene germylene andP24- 137.1141.0-141.5methanethial, as is the same as the reaction between dichloromethy-P31+R2-112.1-94.0-95.1 .lene germylene and ethylene2s. The energy barriers of steps B andINT33-155.7-153.6E for the reaction between dichloromethylene germylene and-103.723.7-123.4methanethial are 13.7 and 26.2 kJ*mol", respectively (as seen inP33-205.3-209.8-208.4Table 2), while the energy barriers of corresponding steps for thea: B3LYP/6-31+G //3LYP/6-31+G*, b: MP2/6311+//B3LYP/6-31+G",reaction between dichloromethylene germylene and ethylene arec: MP2/6-311+G */MP2/6-311+G "57.7 kJ.mol-' and 42.2 kJ. mol- (at CSD(T//B3LYP/6-31+G*be due to the unstable structure ofP1.level)2), respectively. The reaction between dichloromethylene2.2 Path 2germylene and methanethial is much easier to take place than theIn Path 2, there are three possible pathways, all of the threereaction between dichloromethylene germylene and ethylene.different ways have the common first step, which is the forma-Both P22 and P23 are far from planar structure, for dihedral an-tion of P21. P21 then isomerizes to P22 and P23, or reacts withgles ofC1GeC2S (P22: 21.86°, P23: -13.299), HIClGeH2 (P23: -R2 afterwards and forms P24.61.43° ) and CIlC2GeC12 (P22: -69.35° ) deviate from 0° orThere are two possible ways for the formation of [2+2] cy-cloaddition product P21 between singlet dichloromethyleneSince the sp lone eletron pair and the 4p unoccupied orbitalgermylene and methanethial. One is the direct formation throughon Ge atom do not participate in bond formation, P21 is still an[2+2] cycloaddition reaction, and the other is that reactants com-active intermediate. It is not dificult to predict that P21 can fur-bine into [2+1] π-complex precursor firstly, and then isomizether react with methanethial to form a polycyclic compound. Asinto [2+2] cycloadition product. From the point of view of ther-shown in Fig.2, the third way consists of two steps, a barrier-freemodynamics and dynamics, the ltter is more favourable thanexothermic reaction of 41.6 kJ *mol -+ results in an intermediatethe former. Furthermore, the direct formation of four-membered-INT24, then INT24 isomerizing to P24 with a barrier of26.7 kJ .ring [2+2] cycloaddition product is thermal forbidden accordingmol-!to Woodward-Hoffinann rul.The geometric parameters for the transition states (TS2, TS22,As shown in Fig.3, upon the formation of P21, R1 and R2TS23, and TS24), intermediate (INT24), and products (P21, P22,firstly form INT just the same as Path 1, then INT isomerizes toP23, and P24) appearing in Path 2 between singlet dichloromethy-P21, via TS2. With the reaction going on, the dihedral angleslene germylene and methanethial are given in Fig.3. The ener-C2SC1Ge (INT: -43.0*, TS2: -44.1°, P21: -48.6°) gradually in-gies are listed in Table 1. The potential energy surface for Path 2crease and the GeC2SC1 (INT: 80.69, TS2: 61.0% P21: 48.3) grad- is ilustrated in Fig.2.ually decreases, and the INT finally transforms into the twistedThe unique imaginary frequencies of the transition states TS2,four-membered-ring product P21 via the transition stateTS22, TS23,, and TS24 are 644.7i, 416.2i, 771.5i, and 984.7ithe same time, bond angle of GeC2S (INT: 50.8, TS2: 60.3°，cm-', respectively中國煤化工lates can be af-P21: 78.1) and SC1Ge (INT: 73.19,TS2: 76.19, P21: 78.89) gradu-firmed as the realU二ions of the IRCally increase. Among the four single bonds of the twisted four-of all the transitidMHcNMHGhefrheropti-.No.12CHEN Xin et al. : Cycloaddition Reaction Mechanism between Dichloromethylene Germylene and Methanethial 2233C120.17419/>.C2./14.0C10.194540.11110cIT、0176889495520.17550.218843.20.24347.8 852/0.18444HI94.1.95.62/0.1801C12C0.1829HH2P21TS220.22120.1550 cu117800.19540.17040.16800.2057"Ge20.21090.17010.1854CI0.18991.0940.108CT0.1733HiP22TS23P2H4S.CH30.25792s2 0.1924Ge 03550t30.2458390.29460.2183 54.50.200._2eC1974.4782.187.0 .1085CI917690 2904.109.8C12S10.1822a1SI1791INT24TS2424Fig.3 Optimized structures of involved species for Path 2 at MP2/6-311+G* levelbond length in nm and bond angle in degreemization of the primary IRC results, TS2 connects INT and P21,2.3 Path 3TS22 connects P21and P22, TS23 connects P21 and P23, TS24connects INT24 and P24.identical first step and different second step. The first step is theAccording to Fig.2, it can be directly seen that all the threeformation ofP31, a barrier-free exothermic reaction of 103.4 kJ.possible pathways of Path 2 consist of two steps. The first step ismol-+ results in an intermediate INT, then INT isomerizes to P31completely identical, but the activation barrier of their next stepwith a barrier of0.7 kJ. mol-' (via TS3).differ remarkably (184.6 kJ●mol- for P23, 26.2 kJ●mol- for P22,P31 is more stable than P21 with a lower energy of95.1 kJ.26.7 kJ . mol- for P24), so the most favorable pathway is the for-mol-. The favorable path for the isomerization between P31 andmation of P22 and P24 in Path 2.P21 is that they first convert into INT, but the activation barriersfor these conversions are high up to 112.5 and 194.6 kJ mol-, re-Table 2 Activation barriers of involved reactions atspectively. Hence, isomerization between them is very difficult,different levelsand both of them have relative strong stability. At the same time,E/(kJ.mol-)the activation barrier of step B is 13.0 kJ●mol- higher than thatReaction_Cof step C, so it indicates that Path 3 has advantage over Path2 inAINT- +TS1)9933.their competition, and Path 3 becomes the dominant pathway.B(INT→TS2)7.116.813.7P31 can isomerize to P32 via TS32 with activation barrier ofC(INT- →TS3).22.4).7104.7 kJ.mol-, and it also can continue reacting with R2. In thisD(P21→TS23)1559184.course, a barrier free exothermic reaction of 60.6 kJ●mol-' reE(P21→TS22)26.2sults in an intermnediate INT33, then INT33 isomerizes to P33F(P31→TS32)62.5107.6104.7with a barrier of 32.3 kJ.mol- (wvia TS33). From above discussion,G(NT24- +TS24)23.922.9we can conclude that formation of P32 is difficult because of itsH(INT33- →+TS33)2.032.3too high activatio中國煤化工is easier. Thea: B3LYP/6-31+G //B3LYP/6-31+G*. b: MP2/6-311++G* //B3LYP/6-31+G".unique imaginary心二tes TS3, TS32,c: MP2/6-311+G //MP2/6-311+G "; A-H are the reaction steps shown in Fig.2.and TS33 are 780MHc N M H speciveye The.2234 .Acta Phys. -Chim. Sin., 2008Vol.240.17360.1723H20.1664HC127136H'H, H2C212! 0.10.18340.227043.60.23710.205421365.4.4 83.0.2306135.50.23820.21320.22310.2255S3ie?31TS32Ccn.32H30.1616.H3H40.17680.1788 C101965.7109.20.1734.0.204017900.1838H3 .Ge/79. 104.57c1H20.17927 020050.22130.2278s19218，0.2316Gec11 GeINT33TS3333Fig.4 Optimized structures of involved species for Path 3 at MP2/6-311+G * levelbond lengh in nm and bond angle in degreegeometric parameters for the transition-states(TS3, TS32, andaction has an excellent selectivity.TS33), intermediate (INT33), and products (P31, P32, and P33)appearing in Path 3 are given in Fig.4. The energies are listed inReferencesTable 1. The potential energy surface for Path 3 is ilustrated in1 Nagendran, S.; Roesky, H. W. Oranomaallics. 2008, 27: 457Fig.2. .2 Sweeder, R. D.; Edwards, F. A; Miller, K. A; Banaszak Holl, M.M; Kampf, J. W. Organometallics, 2002, 21: 4573 Conclusions3 Wegner, G. L; Berger, R. J. F; Schier, A: Schmidbaur, H.According to above analyses, the major conclusions can beOranomallics, 2001, 20: 418drawn as follows:4 Huck, L. A; Leigh, W. J. Organometallics, 2007, 26: 1339(1) For the reactions between dichloromethylene germylene5 Koch, R.; Bruhn, T; Weidenbruch, M. Organomtallics, 2004, 23:and methanethial or ethylene, direct [2+2] cycloaddition reac-1570tions are unfavourable, their common first reaction step is the6 Su, M. D; Chu, s. Y. J. Am. Chem. Soc, 1999, 121: 11478formation of π-complex precursor. The reaction between dichlo-7 Litz, K. E; Kampf, J. W.; Banaszak Holl, M. M. J. Am. Chem. Soc,romethylene germylene and methanethial is much easier to take1998, 120: 7484place than the reaction between dichloromethylene germyleneand ethylene.8 Matsumoto, T; Tokitoh, N; Okazaki, R. J. Am. Chem. Soc, 1999,121: 8811 .(2) Germacyclopropanes, unlike cyclopropanes, are quite un-stable compounds, they can revert thermally to their precursors.9 Lu, X.: Tian, F; Zhang, Q. J. Phys. Chem. B, 2003, 107: 8388(3) On the basis of the surface energy profle obtained at MP2/10 Xu, Y.J; Zhang, Y. F,Li,J.Q J. Plhys. Chem. C, 2007, 111:6-311+G *// MP2/6-311+G* level for the cycloaddition reaction3729between singlet dichloromethylene germylene and methanethial, .11 Zhu, Q. Y; Roskamp, E. J.J. Org. Chem., 1992, 57: 5281it can be predicted that the dominant reaction pathway of this re-12 Gottried, A. C.; Wang, J; Wilson, E. E:; Beck, L. W: Banaszakaction consists of three steps: the two reactants first form an in-Holl, M. M; Kampf, J. w. Inorg. Chem, 2004, 43: 7665termediate INT through a barrier-free exothermic reaction of13 Wilhelm, P. N. Chem. Rev., 1991, 91: 311103.4 kJ.mol-"; this intermediate then isomerizes to product P3114 Hastie, J. W:; Hauge, R. H; Margrave, J. L. J. Mol. Spectrose.,via a transition-state TS3 with a barrier of 0.7 kJ . mol+; finally,1969, 29: 152P31 further reacts with methanethial to form the germanic het15 Karolczak, J; Zhuo, Q: Clouthier, D. J; Davis, W. M.; Goddard, J.eropolycyelic product P33, for which the barrier is 32.3 kJ.mol*.D. J. Chem. Phys, 1993, 98: 60The rate of this reaction path considerably differs from other16 Nefedov, O. M中國煤化工i6: 201competitive reaction paths, indicating that this cycloaddition re-17 Satge,J; MasscYHCNM H G"". 1973, 56: I.No.12CHEN Xin et al:Cycloaddition Reaction Mechanism between Dichloromethylene Germylene and Methanethial 223518 Zurawski, B.; Kutzelnigg. W. J. Am. Chem. Soc, 1978, 100: 265430 Tsuzuki, S; Luthi, H. P. J. Chem. Phys, 2001, 114: 394919 Rondan, N. G.; Houk, K. N; Moss, R. A. J. Am. Chem. Soc.. 1980,31 Ujaque, G; Lee, P. s; Houk, K. N; Hentemann, M. F; Danishefsky,102: 1770s. J. Chem. J. Eur., 2002, 8: 342320 Su, M. D; Chu, s. Y. J. Am. Chem. Soc., 1999, 121: 1147832 Kurita, N:: Sekin, H. Int. J. Quantum Chem, 2003, 91: 35521 Houk, K. N:; Rondan, N. G; Mareda, J. Tetrahedron, 1985, 41:33 Ye, X;Li, Z. H: Wang, W:; Fan, K: Xu, W.; Hua, Z. Chem. Phys.Le., 2004, 397:5622 Moss, R. A: Yan, S.; Krogh-Jespersen, K. J. Am. Chem. Soc,34 Liu, L. Y; Geng, z. Y:; Zhao,C. Y; Wang, Y. C; Li, Z. H. Acta1998, 120: 1088Phys. -Chim. Sin. 2007, 23: 217劉樂燕耿志遠，趙存元，23 Lu,X. H; Xiang, P. P.:; Che, x; Yang, X. L. J. Mol. Struct. -王永成，李朝暉.物理化學學報, 2007, 23: 217] .Theochem, 2008, 854: 1035 Zheng, W. R.: Fu, Y; Liu, L; Guo, Q. X. Acta Plrys. -Chim. Sin,24 Lu, X. H: Xiang, P. P.; Wei, R.; Che, x. J. Mol. Srruct. -2007,23: 1018 [鄭文銳, 傅堯劉磊郭慶祥.物理化學學Theochem, 2008, 853: 82報, 2007, 23: 1018]25 Lu,X. H:Xu, Y. H; Yu, H. B.; Lin, H Chin. J. Chem., 2005, 23:36 Tan, X; Wang, W; Li, P.:; Wang, Q; Zheng, G; Liu, F.J. Organomet. Chem, 2008, 693: 47526 Toulokhonova, I. S.; Timokhin, V. L; Bunck, D. N; Guzei, L;37 Bachmann, C.:; Frapper, G. Chem. Plhys. Lett, 2008, 457: 292Wes, R; Miller, T. Eur. J. lnorg. Chem, 2008, 14: 234438 Corsaro, A; Chiacchio, M. A.; Pistara, V:; Reseifina, A; Vitorino,27 Su, M. D; Chu, s. Y. Chem. Plhys. Lett, 2004, 394: 231E. Tetrahedron, 2008, 64: 865228 Frisch, M. J; Trucks, G. W.; Schlegel, H. B.; et al. Gaussian 98,39 Wong, M. w. Chem. Plhys. Lett, 1996, 256: 391Revision A. 3. Pttsburgh, PA: Gaussian Ince, 199840 Hoffmann, R. J. Am. Chem. Soc, 1968, 90: 147529 Kurita, N. Tanaka, s; Itoh, s. J. Phys. Chem. A, 2000, 104: 8114中國煤化工MHCNMH G.