Co_3(CO)_7(μ_3-S)[μ, η~2-SCNC (O)C (R_1) (R_2)N (COR_3)]的合成和晶体结构

Co2（CO8）分别与4种硫代乙内酰脲S＝CNHC（O）C（R1）（R2）N（COR3）反应，得到4个新的含硫代乙内酰脲桥基双齿配位的三核钴羰基硫簇合物．用元素分析、IR、1HNMR和MS等手段表征了它们的结构，用X射线衍射测定了其中一个簇合物CO3（CO）7（μ3－S）［μ，η2－SCNC（O）C（CH3）（CH3）N（COCH3）］（IV）的晶体结构，晶体属三斜晶系，P1空间群，晶胞参数：a＝0．8456（3）nm，b＝1．1534（3）nm，c＝1．1990（4）nm；a＝107．36（3）°，β＝108．44（5）°，γ＝90．18（3）°；V＝1．052（6）nm3，Z＝2，F（000）＝584，Dc＝1．86g／cm3，μ＝25．71cm－1，最终偏离因子R＝0．046，Rw＝0．058．     

乙酰基的电子激发态

对乙酰基的基态（X12A′）和激发态进行了理论和实验研究。通过采用MRSDCI和MP2方法计算，获得了CH3CO自由基的四个电子激发态（A12A″，B22A′，C32A′，D22A″），其垂直激发能分别为250．8kJ·mol－1，472．3kJ·mol－1，645．8kJ·mol－1和674．7kJ·mol－1。运用时间分辨付里叶红外光谱仪（TR－FTIR）分别研究了CH3CO自由基的热解和光解反应，观察到初生产物CO（V）的红外发射光谱．势垒仅为75．2kJ·mol－1的基态CH3CO极易热解．532um的激光只能将CH3CO激发到束缚态A12A″，故未观察到CO信号；而248nm或266nm的激光可使CH3CO发生B22A′←X12A′跃迁，生成高振动激发的CO（V8）产物．     

OH+ C2H2N←C2H3 + NO→CH3 + NCO反应机理的密度泛函理论研究

应用密度泛函理论研究了反应通道(a)C2H3 NO→CH3 NCO和(b)C2H3 NO→OH C2H2N的反应机理．在B3LYP／6-31G(d)水平上优化了反应物、中间体、过滤态、产物的几何构型，通过频率分析确定了11个中间体和10个过渡态．所有的反应物、中间体、过渡态、产物都在CCSD／6-311 G(d，P)水平上进行了单点能较正．并讨论了反应的异构化过程．计算结果表明10是能量最低的中间体，比反应物的能量低308．479kJ／mol；过渡态1／3，2／5，3／4，4／8比反应物的能量高，其中3／4是能量最高的过渡态，比反应物的能量高91．894kJ／mol．通道(a)和(b)的理论放热值分别为111．059和96．619kJ／mol．     

化学高考总复习单元练习七 有机化学(B)

第Ⅰ卷（选择题,共84分）一、选择题（本题包括5小题,每小题3分,共15分。每小题只有一个选项符合题意）1．下列物质肯定是纯净物的是（）（A）天然气（B）分子式为C2H6O的物质（C）聚氯乙烯（D）分子式为CH2Cl2的物质2．下列物质中最难电离出H＋的是（）（A）CH3COOH（B）C2H5OH（C）HOH（D）C6H5OH3．分子式为CxHyOz的有机物1mol充分燃烧,若耗氧量及生成CO2和水的分子数之比为1：1：1,则下列关系可能正确的是（）（A）x＝z＝y／2（B）x＝y＝z（C）x＝y＝2z（D）x＝y／2＝2z4．同温同压下,同体积的A、B2种气体或蒸…     

以钼酸盐阴离子柱撑镁铝水滑石为前驱物的加氢脱硫催化剂 Ⅱ.MoS2/Mg(Al)O的吸附性能和HDS催化活性

 通过对氧吸附量、吸附热及反应动力学参数的测定,表征了MoS2在Mg（Al）O上的分散状态及能量性质．结果表明,硫化态MoS2和氧化态MoO3一样,以单分子层分散在载体Mg（Al）O的表面,而且两者的分散阈值均为4．77μmol／m2,说明MoO3硫化后仍保持其原来的分散状态．以噻吩为吸附质,MoS2／Mg（Al）O催化剂的吸附热随着MoO3含量的变化而变化：有三种不同的区域,即Q1＝23．2～23．8kJ／mol（w（MoO3）＝6．02％～9．34％）,Q2＝15．5～16．1kJ／mol（w（MoO3）＝11．89％～15．83％）,Q3≈30．0kJ／mol（w（MoO3）＞21．65％）．MoS2／Mg（Al）O催化剂上噻吩HDS反应的活化能随着MoO3含量的变化情况与吸附热的变化情况相似．随着MoO3含量的增加,催化剂的活性线性升高达极大值后又下降．     

四核钴羰基簇合物CO_4(CO)_8(μ-CO)_2(μ_4-PSR)_2的合成和晶体结构

通过Co_2（CO）_8与二气烧流基酸RSPCI_2［R＝－CH_3－C_2H_5，－C（CH_3）_3，－（CH_2）_4H_3］反应，得到4个新簇合物．除用元素分析、IR、~1HNMR和MS表征其结构外，还用X光衍射法测定了侯会物CO_4（CO）_8（μ-CO）_2（μ_4－PSR）_2小的单品结构该簇合物用单斜晶系，P21／C空间群．晶胞参数为α＝8．445（3），b＝8．562（3），c＝17．125（6），β＝104．26（3）°；V＝1200．1A3；Dc＝1．9379cm~3μ＝3．058mm~(－1)；F（000）＝688．结构分析表明，四个Co原子形成平面矩形，两个PSR四重桥基分别在四钻平面上下盖帽构成Co_4P_2类人面体骨架，骨架为D_(2h)点群对称性．PSR配体为4e供体，与四个钴原子成键．     

双取代铵氧化物(R2HNO)与双取代羟胺(R2NOH)的 相互转换机制的量子化学研究

在B3LYP/6-311＋＋G(d,p)水平下, 首次对一系列双取代铵氧化物(R2HNO)与双取代羟胺(R2NOH) [R＝CH3, NH2, OH, F, CH2CH3, CH(CH3)2, C(CH3)3]同分异构体的相互转换机制进行了理论计算研究, 并与已知的H3NO和H2NOH进行了比较. 结果表明, 相对于双取代羟胺(R2NOH), 按照H＜CH3＜NH2＜OH＜F的顺序, 增加取代基R的电负性有助于提高双取代铵氧化物(R2HNO)的热力学和动力学稳定性. 此外, 对烷基取代基R [R＝CH3, CH2CH3, CH(CH3)2, C(CH3)3], 其空间位阻越大越能增加双取代铵氧化物(R2HNO)的热力学稳定性, 动力学稳定性也有相应增加, 但不显著. 对所研究的7种取代基[R＝CH3, NH2, OH, F, CH2CH3, CH(CH3)2, C(CH3)3], R2HNO向R2NOH转换的能垒介于27.0～56.3 kcal/mol之间, 表明在气相条件下极有可能观测到双取代铵氧化物(R2HNO).     

束-气条件下He(23S)与CH3Cl及CH3I的传能研究

在束-气条件下，通过检测产物的化学发光，研究了亚稳电子激发态He（23S）原子与CH3Cl、CH3I传能反应.采用参比反应的方法，测得了由上述反应产生的主要碎片CH（A2△）、CH（B2∑-）、CH（C2∑+）和H*形成速率常数．通过对测得的CH（A2△－X2∏r）和CH（B2∑-－X2∏r）色散谱进行计算机模拟，获得了初生态的CH（A2△，v＝0－2）和CH（B2∑-，v＝0态）的振动-转动布居，实验结果表明，CH（A2△，v＝0）态的转动布居是呈双Boltzman分布的，并且反应的可资用能大部分将转变成产物的平动能．根据实验结果和反应阈能的分析，本文对He（23S）与CH3Cl／CH3I传能反应机理进行了探讨。     

Co_2Fe(μ_3-S)(CO)_7(CH_3CSNH)的合成与结构

用Co2（CO）8与CH3CSNH2反应制得产物Ⅰ，又用Na2Fe（CO）4与Ⅰ反应制得产物Ⅱ（Ⅰ：Co3（μ3－S）（CO）7（CH3CSNH），Ⅱ：Co2Fe（μ3-S）（CO）7（CH3CSNH）．通过元素分析。IR、UV、1HNMR、MS表征并用X射线衍射法测得Ⅱ的单晶结构.该簇合物属三斜晶系、PT空间群，晶胞参数：a=0．9203（1），b=1．1296（2），c=1.1425（2）nm；α=116．40°（2），β＝101．92°（2），γ＝92．58°（1）；z＝2，V=1．2162nm3，Dc＝1．698cm3，μ＝21．89cm-1.结构分析表明，Co2FeS构三角锥分子骨架，所有CO均为端基配体，S1为面桥基配体，CH3CSNH为双齿配体，与Co、Fe形成五元环结构．     

CH3S自由基H迁移异构化及脱H2反应的直接动力学研究

采用密度泛函方法（MPW1PW91）在6．311G（d,p）基组水平上研究了CH3S自由基H迁移反应CH3S→CH2SH（R1）,脱H2反应CH3S→HCS＋H2（R2）以及脱H2产物HCS异构化反应HCS→CSH（R3）的微观动力学机理．在QCISD（t）／6．311＋＋G（d,p）／／MPW1PW91／6．311G（d,p）＋ZPE水平上进行了单点能校正．利用经典过渡态理论（TST）与变分过渡态理论（CVT）分别计算了各反应在200-2000K温度区间内的速率常数K^TST和k^CVT,同时获得了经小曲率隧道效应模型（SCT）校正后的速率常数萨k^CVT/SCT．结果表明,反应R1,R2和R3的势垒△E^≠分别为160．69,266．61和241．63kJ／mol。R1为反应的主通道．低温下CH3S比CH2SH稳定,高温时CH2SH比CH3S更稳定．另外,速率常数计算结果显示,量子力学隧道效应在低温段对速率常数的计算有显著影响,而变分效应在计算温度段内对速率常数的影响可以忽略．     

Clusters of hydrated methane sulfonic acid CH3SO3H.(H2O)n (n = 1-5): a theoretical study

Ab initio and density functional methods have been used to examine the structures and energetics of the hydrated clusters of methane sulfonic acid (MSA), CH3SO3H.(H2O)n (n = 1-5). For small clusters with one or two water molecules, the most stable clusters have strong cyclic hydrogen bonds between the proton of OH group in MSA and the water molecules. With three or more water molecules, the proton transfer from MSA to water becomes possible, forming ion-pair structures between CH3SO3- and H3O+ moieties. For MSA.(H2O)3, the energy difference between the most stable ion pair and neutral structures are less than 1 kJ/mol, thus coexistence of neutral and ion-pair isomers are expected. For larger clusters with four and five water molecules, the ion-pair isomers are more stable (>10 kJ/mol) than the neutral ones; thus, proton transfer takes place. The ion-pair clusters can have direct hydrogen bond between CH3SO3- and H3O+ or indirect one through water molecule. For MSA.(H2O)5, the energy difference between ion pairs with direct and indirect hydrogen bonds are less than 1 kJ/mol; namely, the charge separation and acid ionization is energetically possible. The calculated IR spectra of stable isomers of MSA.(H2O)n clusters clearly demonstrate the significant red shift of OH stretching of MSA and hydrogen-bonded OH stretching of water molecules as the size of cluster increases.     

Synthetic and computational studies of the palladium(iv) system Pd(alkyl)(aryl)(alkynyl)(bidentate)(triflate) exhibiting selectivity in C-C reductive elimination

Synthetic routes to methyl(aryl)alkynylpalladium(iv) motifs are presented, together with studies of selectivity in carbon-carbon coupling by reductive elimination from Pd(IV) centres. The iodonium reagents IPh(C[triple bond, length as m-dash]CR)(OTf) (R = SiMe(3), Bu(t), OTf = O(3)SCF(3)) oxidise Pd(II)Me(p-Tol)(L(2)) (1-3) [L(2) = 1,2-bis(dimethylphosphino)ethane (dmpe) (1), 2,2'-bipyridine (bpy) (2), 1,10-phenanthroline (phen) (3)] in acetone-d(6) or toluene-d(9) at -80 °C to form complexes Pd(IV)(OTf)Me(p-Tol)(C[triple bond, length as m-dash]CR)(L(2)) [R = SiMe(3), L(2) = dmpe (4), bpy (5), phen (6); R = Bu(t), L(2) = dmpe (7), bpy (8), phen (9)] which reductively eliminate predominantly (>90%) p-Tol-C[triple bond, length as m-dash]CR above ～-50 °C. NMR spectra show that isomeric mixtures are present for the Pd(IV) complexes: three for dmpe complexes (4, 7), and two for bpy and phen complexes (5, 6, 8, 9), with reversible reduction in the number of isomers to two occurring between -80 °C and -60 °C observed for the dmpe complex 4 in toluene-d(8). Kinetic data for reductive elimination from Pd(IV)(OTf)Me(p-Tol)(C[triple bond, length as m-dash]CSiMe(3))(dmpe) (4) yield similar activation parameters in acetone-d(6) (66 ± 2 kJ mol(-1), ΔH(?) 64 ± 2 kJ mol(-1), ΔS(?)-67 ± 2 J K(-1) mol(-1)) and toluene-d(8) (E(a) 68 ± 3 kJ mol(-1), ΔH(?) 66 ± 3 kJ mol(-1), ΔS(?)-74 ± 3 J K(-1) mol(-1)). The reaction rate in acetone-d(6) is unaffected by addition of sodium triflate, indicative of reductive elimination without prior dissociation of triflate. DFT computational studies at the B97-D level show that the energy difference between the three isomers of 4 is small (12.6 kJ mol(-1)), and is similar to the energy difference encompassing the six potential transition state structures from these isomers leading to three feasible C-C coupling products (13.0 kJ mol(-1)). The calculations are supportive of reductive elimination occurring directly from two of the three NMR observed isomers of 4, involving lower activation energies to form p-TolC[triple bond, length as m-dash]CSiMe(3) and earlier transition states than for other products, and involving coupling of carbon atoms with higher s character of σ-bonds (sp(2) for p-Tol, sp for C[triple bond, length as m-dash]C-SiMe(3)) to form the product with the strongest C-C bond energy of the potential coupling products. Reductive elimination occurs predominantly from the isomer with Me(3)SiC[triple bond, length as m-dash]C trans to OTf. Crystal structure analyses are presented for Pd(II)Me(p-Tol)(dmpe) (1), Pd(II)Me(p-Tol)(bpy) (2), and the acetonyl complex Pd(II)Me(CH(2)COMe)(bpy) (11).     

硝基甲烷异构化反应势能面的ab initio研究

在B3LYP/6-311+ +G(2d,2p)水平上,优化得到硝基甲烷CH3NO2的10种异构体和23个异构化反应过渡态,并用G2MP2方法进行了单点能计算.根据计算得到的G2MP2相对能量,探讨了CH3NO2势能面上异构化反应的微观机理.研究表明,反应初始阶段的CH3NO2异构化过程具有较高的能垒,其中CH3NO2的两个主要异构化反应通道,即CH3NO2→CH3ONO和CH3NO2→CH2N(O)OH的活化能分别为270.3和267.8 kJ/mol,均高于CH3NO2的C-N键离解能.因而,从动力学角度考虑, CH3NO2的异构化反应较为不利.     

C70X2(X=H,F, Cl)的稳定性和电子光谱

用INDO方法研究C70H2四种异构体的稳定性, 表明其最稳定异构体为1, 9-C70H2和7, 8-C70H2, 两者能量差为16.3KJ.mol^-^1, 与实验值及ab initio计算值接近; 光谱计算表明, 其特征吸收峰与实验值一致。在此基础上预测C70F2和C70Cl2的稳定性和电子光谱, 表明C70F2四种异构体的稳定性顺序与C70H2一致, 而C70Cl2则以21, 42-异构体最为稳定。二者的电子光谱与C70H2极其相似只是在500nm以上有细微差别。     

加成产物HC60[CH2C(CH3)=CH2]的电子结构和UV谱

用INDO方法研究C60与2-甲基烯丙基氯化镁的加成产物HC60[CH2C(CH3)=CH2]的两种异构体的结构和UV谱, 表明1,2-加成产物具有Cs对称性, 1,4-加成产物具有C1对称性, 且前者比后者总能量低, 因而更易于形成。产物中2-甲基烯丙基与C60之间靠极性共价键连接, 并发生前者向后者的电子转移。以此优化构型为基础, 计算两种产物异构体的UV谱, 与实验值一致。同时对电子跃迁进行理论指认, 讨论了产物UV谱带红移的原因。     

C(arenium)-C(alkyl) bond making and breaking: key process in the platinum-mediated C(aryl)-C(alkyl) bond formation. Analogies to organic electrophilic aromatic substitution

The reaction of cationic platinum aqua complexes 2 [Pt(C(6)H(2)[CH(2)NMe(2)](2)-E-4)(OH(2))](X') (X' = SO(3)CF(3), BF(4)) with alkyl halides RX gave various air-stable arenium complexes 3-5 containing a new C-C bond (R = Me, 3; Et, 4; Bn, 5). Electron-releasing oxo-substituents on the aromatic ligand (E = e.g., OH, b; OMe, c) enhance the reactivity of the aqua complex 2 and were essential for arenium formation from alkyl halides different from MeX. This process is initiated by oxidative addition of alkyl halides to the platinum(II) center of 2, which affords (alkyl)(aryl) platinum(IV) complexes (e.g., 9, alkyl = benzyl) as intermediates. Spectroscopic analyses provided direct evidence for a subsequent reversible 1,2-sigmatropic shift of the alkyl group along the Pt-C(aryl) bond, which is identical to repetitive C(arenium)-C(alkyl) bond making and breaking and concerted metal reduction and oxidation. Temperature-dependent NMR spectroscopy revealed DeltaH degrees = -1.3 (+/- 0.1) kJ mol(-1), DeltaS degrees = +3.8 (+/- 0.2) J mol(-1) K(-1), and DeltaG degrees (298) = -2.4 (+/- 0.1) kJ mol(-1) for the formation of the arenium complex 5b from 9 involving the migration of a benzyl group. The arenium complexes were transformed to cyclohexadiene-type addition products 7 or to demetalated alkyl-substituted arenes, 8, thus completing the platinum-mediated formation of a sp(2)-sp(3) C-C bond which is analogous to the aromatic substitution of a [PtX](+) unit by an alkyl cation R(+). The formation of related trimethylsilyl arenium complexes 6 suggests arenium complexes as key intermediates, not only in (metal-mediated) sp(2)-sp(3) C-C bond making and breaking but also in silyl-directed cyclometalation.     

Stable enols of amides ArNHC(OH)=C(CN)CO(2)R. E/Z enols,equilibria with the amides,solvent effects,and hydrogen bonding

The structures of anilido cyano(fluoroalkoxycarbonyl)methanes ArNHCOCH(CN)CO(2)R, where R = CH(2)CF(3) or CH(CF(3))(2), Ar = p-XC(6)H(4), and X = MeO, Me, H, or Br, were investigated. In the solid state, all exist as the enols ArNHC(OH)=C(CN)CO(2)R 7 (R = CH(2)CF(3)) and 9 (R = CH(CF(3))(2)) with cis arrangement of the hydrogen-bonded ROC=O.HO moiety and a long C1=C2 bond. The product composition in solution is solvent dependent. In CDCl(3) solution, only a single enol is observed, whereas in THF-d(8) and CD(3)CN, two enols (E and Z) are the major products, and the amide is the minor product or not observed at all (K(Enol) 1.04-9 (CD(3)CN, 298 K) and 3 to >/=100 (THF, 300 K)). The percentage of the amide and the Z-enol increase upon an increase in temperature. In all solvents, the percent enol is higher for 9 than for 7. In CD(3)CN, more enol is observed when the aryl group is more electron-donating. The spectra in DMSO-d(6) and DMF-d(7) indicate the presence of mostly a single species, whose spectra do not change on addition of a base and is ascribed to the anion of the ionized carbon acid. Comparison with systems where the CN is replaced by a CO(2)R group (R = CH(2)CF(3), CH(CF(3))(2)) shows a higher percentage of enol for the CN-substituted system. Intramolecular (to CO(2)R) and intermolecular hydrogen bonds determine, to a significant extent, the stability of the enols, their Z/E ratios (e.g., Z/E (THF, 240 K) = 3.2-4.0 (7) and 0.9-1.3 (9)), and their delta(OH) in the (1)H spectra. The interconversion of Z- and E-enol by rotation around the C=C bond was studied by DNMR, and DeltaG() values of >/=15.3 and 14.1 +/- 0.4 kcal/mol for Z-7 and Z-9 were determined. Features of the NMR spectra of the enols and their anions are discussed.     

Photochemical reactions of (eta 5-cyclopentadienyl)bis(t-butylacrylate) rhodium with silanes: dynamics of isomer interconversion via Rh(eta 2-silane) species

The compound CpRh(C(2)H(3)CO(2)(t)Bu)(2) 1 has been synthesised as a mixture of two pairs of interconverting isomers which differ in the relative orientations of the alkene substituents. The four isomers have been fully characterised by NMR spectroscopy. When complex 1 is photolysed in the presence of a silane, HSiR(2)R'R(2)R'= Et(3), Me(3), HEt(2), (OMe)(3) and Me(2)Cl] the corresponding Si-H oxidative addition products CpRh(SiR(2)R')(H)(C(2)H(3)CO(2)(t)Bu) and CpRh(H)(2)(SiR(2)R')(2) are formed. The Rh(III) complexes CpRh(SiR(2)R')(H)(C(2)H(3)CO(2)(t)Bu) exist in two isomeric forms of comparable energy which interconvert in an intramolecular process that does not involve a reversible [1,3] hydride or [1,3] silyl migration. The hydride (1)H NMR resonances for these species consequently broaden before coalescing into a single peak. For R(2)R'= Et(3), the activation parameters for interchange from the major to minor isomer were Delta H++= 60.2 +/- 2 kJ mol(-1) and Delta S++= 8 +/- 9 J mol(-1) K(-1), while for R(2)R'= Me(3) and Et(2)H, Delta H++= 61.5 +/- 1 kJ mol(-1), Delta S++= 6 +/- 5 J mol(-1) K(-1), and Delta H++= 61.8 +/- 3 kJ mol(-1), Delta S++= 12 +/- 9 J mol(-1) K(-1) respectively for conversion from the major isomer to the minor. For these complexes an eta(2)-Rh-H-Si transition state or intermediate is consistent with the evidence. When R(2)R'=(OMe)(3) and Me(2)Cl the change in appearance of the hydride resonances is more complex, with the activation parameters for interchange from the major to minor isomer for the former species being Delta H++= 78.3 +/- 2 kJ mol(-1) and Delta S++= 30 +/- 7 J mol(-1) K(-1) while for Me(2)Cl the barrier proved too high to measure before decomposition occurred. The complex spectral changes could be simulated when a discrete eta(2)-Rh-H-Si intermediate was involved in the isomer interconversion process and hence silane rotation in all these systems is proposed to involve two isomers of CpRh(eta(2)-HSiR(2)R')(C(2)H(3)CO(2)(t)Bu).     

Isomer- and species-selective infrared spectroscopy of jet-cooled 7H- and 9H-2-aminopurine and 2-aminopurine·H2O clusters

The infrared (IR) spectra of the supersonic-jet cooled 9H- and 7H-tautomers of 2-aminopurine (2AP) and of the 9H-2-aminopurine·H(2)O monohydrate clusters have been measured by mass- and species-selective IR-UV double resonance spectroscopy in the 3200-3900 cm(-1) region, covering the N-H and O-H stretching vibrations. The spectra are complemented by density functional (B3LYP and PW91) and by second-order M?ller-Plesset (MP2) calculations of the electronic energies and vibrational frequenciesof the respective 2AP tautomers and clusters. The 9H- and 7H-2-aminopurine tautomers were definitively identified by the shifts of their NH and NH(2) symmetric and asymmetric stretching frequencies and by comparison to the B3LYP/TZVP calculated IR spectra. The H-bond topologies of the two previously observed 9H-2-aminopurine·H(2)O isomers (Sinha. R. K.; et al. J. Phys. Chem. A2011, 115, 6208) are definitively identified as the "sugar-edge" isomer A and the "trans-amino-bound" isomer B by comparing their IR spectra to the calculated frequencies and IR intensities of the cluster isomers A, B, C, and D, as well as to the IR spectrum of 9H-2AP. The sugar-edge isomer A involves N9-H···OH(2) and HOH···N3 hydrogen bonds and is predicted to be the most stable form. The amino-bound isomer B involves NH(2)···OH(2) and HOH···N1 hydrogen bonds and is calculated to lie 2.5 kJ/mol above isomer A. The H-bond topology of the "cis-amino-bound" isomer C is symmetrically related to isomer B, with a hydrogen bond to the N3 of the pyrimidine group. However, it is calculated to lie 7 kJ/mol above isomer A and indeed is not observed in the supersonic jet. Isomer D involves a single H-bond to the N7 position, is predicted to be 14 kJ/mol above A and is therefore not observed.     

Insertion reactions of hydridonitrosyltetrakis(trimethylphosphine) tungsten(0)

[W(H)(NO)(PMe3)4] (1) was prepared by the reaction of [W(Cl)(NO)(PMe3)4] with NaBH4 in the presence of PMe3. The insertion of acetophenone, benzophenone and acetone into the W-H bond of 1 afforded the corresponding alkoxide complexes [W(NO)(PMe3)4(OCHR1R2)](R1 = R2 = Me (2); R1 = Me, R2 = Ph (3); R1 = R2 = Ph (4)), which were however thermally unstable. Insertion of CO2 into the W-H bond of yields the formato-O complex trans-W(NO)(OCHO)(PMe3)4 (5). Reaction of trans-W(NO)(H)(PMe3)4 with CO led to the formation of mer-W(CO)(NO)(H)(PMe3)3 (6) and not the formyl complex W(NO)(CHO)(PMe3)4. Insertion of Fe(CO)(5), Re2(CO)10 and Mn2(CO)10 into trans-W(NO)(H)(PMe3)4 resulted in the formation of trans-W(NO)(PMe3)4(mu-OCH)Fe(CO)4 (7), trans-W(NO)(PMe3)4(mu-OCH)Re2(CO)9 (8) and trans-W(NO)(PMe3)4(mu-OCH)Mn2(CO)9 (9). For Re2(CO)10, an equilibrium was established and the thermodynamic data of the equilibrium reaction have been determined by a variable-temperature NMR experiments (K(298K)= 104 L mol(-1), DeltaH=-37 kJ mol(-1), DeltaS =-86 J K(-1) mol(-1)). Both compounds 7 and 8 were separated in analytically pure form. Complex 9 decomposed slowly into some yet unidentified compounds at room temperature. Insertion of imines into the W-H bond of 1 was also additionally studied. For the reactions of the imines PhCH=NPh, Ph(Me)C=NPh, C6H5CH=NCH2C6H5, and (C6H5)2C=NH with only decomposition products were observed. However, the insertion of C10H7N=CHC6H5 into the W-H bond of led to loss of one PMe3 ligand and at the same time a strong agostic interaction (C17-H...W), which was followed by an oxidative addition of the C-H bond to the tungsten center giving the complex [W(NO)(H)(PMe3)3(C10H6NCH2Ph)] (10). The structures of compounds 1, 4, 7, 8 and 10 were studied by single-crystal X-ray diffraction.