Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
J Phys Chem A. 2011 Oct 13;115(40):11079-86. doi: 10.1021/jp207119c. Epub 2011 Sep 21.
The optimized geometries and corresponding binding energies of complexes between fluorohalides, FX (X = Cl, Br, and I), and isocyanides, CNY (Y = CN, NC, NO(2), F, CF(3), Cl, Br, H, CCF, CCH, CH(3), SiH(3), Li, and Na), were calculated at the MP2(Full)/aug-cc-pVTZ (aug-cc-pVTZ-PP on I) level of theory, without and with basis set superposition error (BSSE) corrections through the counterpoise (CP) method. The optimized complex geometries were analyzed through the Steiner-Limbach relationship, which can be used to establish correlations between the F-X and X-C bond lengths. For all complexes, the correlations were shown to improve considerably when using optimized geometries including BSSE corrections. It was shown that further improvements can be achieved through the introduction of an extended four-parameter form of the Steiner-Limbach relationship which accounts for all differences between the valences associated with the two bonds involving the halogen in an A-X···B complex. The results indicate that chlorine as a halogen bond donor is affected by the basicity of the isocyanides and forms different types of halogen bonds as the F-Cl bond lengthens in parallel with the shortening of the distance between Cl and the isocyanide carbon. This is not observed for iodine and bromine as halogen-bond donors, which is illustrated by the low levels of correlation obtained when applying the standard and extended Steiner-Limbach relationships to the corresponding complexes.
优化了氟卤化物 FX（X=Cl、Br 和 I）与异氰化物 CNY（Y=CN、NC、NO₂、F、CF₃、Cl、Br、H、CCF、CCH、CH₃、SiH₃、Li 和 Na）之间复合物的优化几何形状和相应的结合能，使用 MP2（全）/aug-cc-pVTZ（在 I 上使用 aug-cc-pVTZ-PP）理论水平，不包括和包括基组叠加误差（BSSE）校正，通过反叠（CP）方法。通过 Steiner-Limbach 关系分析了优化的复合物几何形状，该关系可用于建立 F-X 和 X-C 键长之间的相关性。对于所有复合物，当使用包括 BSSE 校正的优化几何形状时，相关性得到了显著改善。结果表明，通过引入扩展的四参数形式的 Steiner-Limbach 关系，可以进一步改进该关系，该关系考虑了涉及卤素的 A-X···B 复合物中两个键相关联的所有价态之间的所有差异。结果表明，作为卤素键供体的氯受到异氰化物的碱性的影响，并形成不同类型的卤素键，因为 F-Cl 键随着与氯键之间距离的缩短而平行拉长。作为卤素键供体的碘和溴没有观察到这种情况，这可以通过应用标准和扩展的 Steiner-Limbach 关系到相应的复合物时获得的低相关性水平来说明。
