Consistent force field calculations. III. Vibrations, conformations, and heats of hydrogenation of nonconjugated olefins
Consistent force field calculations. III. Vibrations, conformations, and heats of hydrogenation of nonconjugated olefins
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一致的力场计算。
DOI：
10.1021/ja00794a003
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发表时间：
1973
影响因子：
15
通讯作者：
S. Lifson
中科院分区：
文献类型：
--
作者：
O. Ermer;S. Lifson
用CFF方法导出了非共轭烯烃的力场。这组能量函数包括双键的拉伸、弯曲、扭转、扭曲和平面外弯曲、非键原子-原子相互作用和双线性交叉项。后者对应于价力场（VFF）型函数，比Urey-Bradley（UBFF）型函数更符合实验。优化的能量参数包括22个脂肪族能量函数和17个双键及其周围的参数。能量参数的最小二乘优化实验数据包括：乙烯-d 0和-d4，反式-和顺式-2-丁烯，异丁烯-d 0和-ds，环己烯-d 0和-d 0，1，4-环己二烯，反式，反式-1，5，9-环十二碳三烯的259个实验指定频率;乙烯、丙烯、顺丁烯和斜丁烯、异丁烯、环戊烯、环己烷、反式环辛烯、顺、顺-1，6-环癸二烯、1，5，9-环十二碳三烯、丁烷、环己烷和环癸烷的44个构象数据;涉及2-丁烯、1，2-甲基-叔丁基乙烯、1，2-二-叔丁基乙烯和五至十元环烯烃的氢化热的十个顺-反差异和过量值（相对于环己烯）。发现cú-2-丁烯的内氢与双键重叠，通过打开C= C-C键角来缓解应力。发现1，4-环己二烯是平面的。对于反式-环辛烯，计算的C-C= C-C扭转角计算为420偏离平面，预测反式-和顺式-环壬烯分别类似于相应的结晶/反式-辛内酰胺及其cb-盐酸盐。不太明显的是环癸烯和它们的硝酸银加合物的相似性。氢化热同意更好地与实验在气相中比在乙酸中，偶极相互作用和其他溶剂的影响干扰。
A force field for nonconjugated olefins was derived by the CFF method. The set of energy functions included stretching, bending, torsion, twisting, and out-of-plane bending of double bonds, nonbonded atomatom interactions, and bilinear cross terms. The latter correspondto the valence force field (VFF) type functions and give mostly somewhat better agreement with experiment than the Urey-Bradley (UBFF) functions used previously. The optimized energy parameters comprise 22 parameters for the aliphatic energy functions and 17 for the double bond and its surroundings. Experimental data for the least-squares optimization of energy param-eters comprise: 259 experimentally assigned frequencies of ethylene-do and-d4, trans-and cw-2-butene, isobutylene-d0 and-ds, cyclohexene-do and-do, 1, 4-cyclohexadiene, and trans, trans, trans-1, 5, 9-cyclododecatriene; 44 con-formational data on ethylene, propene, cis-and skew-\-butene, isobutylene, cyclopentene, cyclohexane, trans-cyclooctene, cw, cw-l, 6-cyclodecadiene, 1, 5, 9-cyclododecatriene, butane, cyclohexane, and cyclodecane; ten cis—trans differences and excess values (over cyclohexene) of heats of hydrogenation involving the 2-butenes, the 1, 2-methyl-/e «-butylethylenes, the 1, 2-di-/er/-butylethyIenes, and the five-to ten-membered ring olefins. The inner hydrogens of cú-2-butene are found to be eclipsed with the double bond, and relief of strain is obtained by open-ing the C= C—C bond angles. 1, 4-Cyclohexadiene is found to be planar. For traw-cyclooctene, the calculated C—C= C—C torsion angle is calculated as 420 off planar, trans-and cw-cyclononenes are predicted to be similar to the corresponding crystalline/ranj-caprylolactam and its cb-hydrochloride, respectively. Less pronounced are the similarities of the cyclodecenes and their silver nitrate adducts. Heats of hydrogenation agree much better with experiments in the gas phase than in acetic acid, where dipolar interactions and other solvent effects interfere.