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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Theoretical Study of Intraolecular Hydrogen Transfer in Thioformohydroxamic Acid and Its Aceto and Fluoro-Substituted Derivatives
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Theoretical Study of Intraolecular Hydrogen Transfer in Thioformohydroxamic Acid and Its Aceto and Fluoro-Substituted Derivatives

机译：硫代异羟肟酸及其乙酰和氟代衍生物中分子内氢转移的理论研究

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摘要

Interconversion f five isomeric tautomers of thioformohydroxamic acid and its aceto- and fluoro-substituted derrivatives via intramolecular hydrogen transfer was investigated by ab initio theoretical calculation.The transfer potential surfaces,the global isomeric structures,and the transition geometries of intramolecular hydrogen transfer were detemined at the MP2/6-31++G** level of calculation.The energy was further analyzed by a single point calculation using MP2/6-31++ G**//MP2/6-31+G**.Not counting the unstable charge separating species (S3)which may be an imprtant conformation in the formation of metal copleses,the order of stability of these tautomers was S2Z>S2E>S1Z>SE,calculate dat the MP2 level with zero point energy consideration.The S2Z AND S2E are thione forms,whereas S1Z and S1E are thiol forms.The ring structure of the transition state construction dominates the energy barrier of the intramolecualr hydrogen transfre,which initiates the interconversion among the five isomeric tautomers.Because the proton attached to the N-atom in thione form is relatively easy to dissociate,we believe that thioformohydroxamic acid in the dissociating protonin the gas phase is an N-acid.However,in the thiol form it is instead a S-acid rather than an O-acid .Substitution effect (aceto and fluoro derivatives)on the stability of tautomeric structures and intramolecular hydrogen transfer barriers was also examined.
机译：从头计算理论研究了硫代甲氧肟酸及其异构体的五个异构体互变异构体的互变。确定了分子内氢转移的势能面，整体异构体结构和过渡几何构型。 MP2 / 6-31 ++ G **计算级别。使用MP2 / 6-31 ++ G ** // MP2 / 6-31 + G **通过单点计算进一步分析能量。不稳定的电荷分离物质（S3），可能是金属胶结形成中的重要构象，这些互变异构体的稳定性顺序为S2Z> S2E> S1Z> SE，在考虑零点能量的情况下计算dat的MP2水平。 AND S2E是硫酮形式，而S1Z和S1E是硫醇形式。过渡态结构的环结构主导着分子内氢转移的能垒，从而引发了五个等位基因之间的相互转化因为以硫酮形式附着在N原子上的质子相对易于解离，我们认为在气相中离解质子中的硫代甲羟肟酸是一种N-酸。但是，在硫醇形式中它是S酸（而不是O酸）。还研究了对互变异构结构和分子内氢转移壁垒稳定性的取代作用（乙酰和氟衍生物）。

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