The multiple bonding in heavier group 14 element alkene analogues is stabilized mainly by dispersion force effects.
The multiple bonding in heavier group 14 element alkene analogues is stabilized mainly by dispersion force effects.
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DOI：
10.1039/c5sc02707a
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发表时间：
2015-11-01
期刊：
影响因子：
8.4
通讯作者：
Power PP
中科院分区：
文献类型：
--
作者：
Guo JD;Liptrot DJ;Nagase S;Power PP
对较重的14族双金属化合物[E{CH(SiMe3)2}2]2和[E{N(SiMe3)2}2]2(E=Ge、Sn2或Pb2)及其单体的计算表明，经验观察到的二聚化主要是由吸引色散力驱动的。用杂化密度泛函理论(DFT)在B3PW91基组上计算了重族14元烯烃类似物[E{CH(SiMe3)2}2]2和[E{N(SiMe3)2}2]2(E=Ge、Sn2或Pb3)的结构和成键及其解离成：E{CH(SiMe3)2}2和：E{N(SiMe3)2}2单体.用色散校正的B3PW91-D3方法对结构进行了重新优化，以产生色散力效应。这些计算基本上再现了四烷基的实验结构数据，但有几个角度例外。对于烷基，在没有色散修正的情况下，计算出的离解能分别为-2.3(Ge)、+2.1(Sn)和-0.6(Pb)kcal mol-1，表明二聚体E-E键结构只对TiN有利。当考虑色散力效应时，计算得到的离解能较高，分别为28.7(Ge)、26.3(Sn)和15.2(Pb)kcal mol-1，表明这三种E-E键二聚体都是有利的。在25℃和1atm下计算的烷基解离热力学数据得到的ΔG值分别为9.4(Ge)、7.1(Sn)和-1.7kcal·moL-1，这表明Ge和Sn二聚体是有利的，而不是铅。这些结果与实验数据相吻合。未经色散校正的等电子四胺取代二聚体[E{N(SiMe3)2}2]2的离解能分别为-7.0(Ge)、-7.4(Sn)和-4.8(Pb)kcal-1，表明这些单体在所有情况下都是有利的。包括色散校正后，得到3.6(Ge)、11.7(Sn1)和11.8(Pb1)kcal-1的值，这表明二聚化是有利的，但不如烷基那么强烈。在25℃和1大气压下，计算的氨基锗、锡和铅的解离热力学数据分别为-12.2、-3.7和-3.6kcalΔ-1，与单体结构的观察结果一致。总体而言，这些数据表明，在这些空间位阻分子中，配位体之间的色散力吸引比第14族元素-元素键更重要，并主要负责金属二基物种的二聚化得到双金属烯。此外，对不解离的二茂锡[Sn{SiMetBu2}2]2的计算表明，吸引色散力是其稳定性的关键。
Computations on the heavier group 14 dimetallenes [E{CH(SiMe3)2}2]2 and [E{N(SiMe3)2}2]2 (E = Ge, Sn, or Pb) and their respective monomers indicated that empirically observed dimerization is principally driven by attractive dispersion forces. The structures and bonding in the heavier group 14 element olefin analogues [E{CH(SiMe3)2}2]2 and [E{N(SiMe3)2}2]2 (E = Ge, Sn, or Pb) and their dissociation into :E{CH(SiMe3)2}2 and :E{N(SiMe3)2}2 monomers were studied computationally using hybrid density functional theory (DFT) at the B3PW91 with basis set superposition error and zero point energy corrections. The structures were reoptimized with the dispersion-corrected B3PW91-D3 method to yield dispersion force effects. The calculations generally reproduced the experimental structural data for the tetraalkyls with a few angular exceptions. For the alkyls, without the dispersion corrections, dissociation energies of –2.3 (Ge), +2.1 (Sn), and –0.6 (Pb) kcal mol–1 were calculated, indicating that the dimeric E–E bonded structure is favored only for tin. However, when dispersion force effects are included, much higher dissociation energies of 28.7 (Ge), 26.3 (Sn), and 15.2 (Pb) kcal mol–1 were calculated, indicating that all three E–E bonded dimers are favored. Calculated thermodynamic data at 25 °C and 1 atm for the dissociation of the alkyls yield ΔG values of 9.4 (Ge), 7.1 (Sn), and –1.7 (Pb) kcal mol–1, indicating that the dimers of Ge and Sn, but not Pb, are favored. These results are in harmony with experimental data. The dissociation energies for the putative isoelectronic tetraamido-substituted dimers [E{N(SiMe3)2}2]2 without dispersion correction are –7.0 (Ge), –7.4 (Sn), and –4.8 (Pb) kcal mol–1, showing that the monomers are favored in all cases. Inclusion of the dispersion correction yields the values 3.6 (Ge), 11.7 (Sn), and 11.8 (Pb) kcal mol–1, showing that dimerization is favored but less strongly so than in the alkyls. The calculated thermodynamic data for the amido germanium, tin, and lead dissociation yield ΔG values of –12.2, –3.7, and –3.6 kcal mol–1 at 25 °C and 1 atm, consistent with the observation of monomeric structures. Overall, these data indicate that, in these sterically-encumbered molecules, dispersion force attraction between the ligands is of greater importance than group 14 element–element bonding, and is mainly responsible for the dimerization of the metallanediyls species to give the dimetallenes. In addition, calculations on the non-dissociating distannene [Sn{SiMetBu2}2]2 show that the attractive dispersion forces are key to its stability.
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影响因子：
3
作者：
Grimme, Stefan
通讯作者：
Grimme, Stefan
DOI：
10.1039/dt9860002387
发表时间：
1986-11-01
期刊：
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
影响因子：
--
作者：
GOLDBERG, DE;HITCHCOCK, PB;SCHILLING, BER
通讯作者：
SCHILLING, BER
影响因子：
16.6
作者：
Grimme, Stefan;Schreiner, Peter R.
通讯作者：
Schreiner, Peter R.
影响因子：
1.7
作者：
BERGNER, A;DOLG, M;PREUSS, H
通讯作者：
PREUSS, H
影响因子：
2.8
作者：
Guo, Jing-Dong;Nagase, Shigeru;Power, Philip P.
通讯作者：
Power, Philip P.