含P_3H_3的π-hole磷键作用及取代效应的理论研究

Theoretical Study on the Properties ofπ-hole Pnicogen Bonds Containing P_3H_3 and Their Substituent Effects

采用量子化学计算方法,在MP2/aug-cc-pVDZ理论水平上对P_3H_3…NCX(X=H,F,Cl,Br,CN,CF_3,OH,CH_3,NH_2,OCH_3)π-hole磷键作用的性质以及取代基的影响进行了理论研究,分析了复合物的稳定结构、相互作用的强度、电子给体和电子受体间的轨道作用及电子密度拓扑性质等.研究表明,P_3H_3与NCX间的π-hole磷键作用为闭壳层非共价相互作用;色散和静电作用占主导地位,极化作用较小.NCX中不同取代基对氮原子上的静电势产生较大影响,进而改变了π-hole磷键作用的强度;较强的吸电子基(CN,CF_3,F)减弱了π-hole磷键作用强度,给电子基(OH,CH_3,OCH_3,NH_2)增加了相互作用的强度.复合物P_3H_3…NCOH中由于存在很强的LP(P)→BD*(O—H)的轨道作用,分子间相互作用强度明显增加.

The properties and effect of substitution on the strength ofπ-hole pnicogen bonds in the P3H3…NCX（X= H,F,Cl,Br,CN,CF3,OH,CH3,NH2,OCH3）complexes were investigated by quantum chemical calculations at the MP2/aug-cc-pVDZ level,include the geometries,interaction energies,orbital interactions,and electron densities.The results indicate that theπ-hole pnicogen bonds belong to the typical closed-shell noncovalent interactions.Moreover,dispersion and electrostatic forces play dominant roles,while the polarization force is small.Examination of the electrostatic potentials of NCY monomers indicates that the substituents have large influence upon the most negative electrostatic potential on the surface of the interacting nitrogen and thus modulate theseπ-hole interactions.The replacement of hydrogen atom of HCN by the strong electron-withdrawing groups（CN,CF3,and F）leads to the interaction energys decrease.On the antrary,the replacement of hydrogen atom by the electron-donating groups（OH,CH3,OCH3,and NH2）increases the strength of in teraction energy.A far greater enhancement of the interaction in the P3H3…NCOH complex arises from the strong LP（P）→BD＊（O-H）orbital interaction.