Alkorta Ibon, Elguero José, Mó Otilia, Yáñez Manuel, Del Bene Janet E
Instituto de Química Médica (IQM-CSIC), Juan de la Cierva 3, 28006-Madrid, Spain.
Phys Chem Chem Phys. 2015 Jan 21;17(3):2259-67. doi: 10.1039/c4cp04574b. Epub 2014 Dec 8.
Ab initio MP2/aug'-cc-pVTZ calculations have been carried out to investigate the structures, binding energies, and bonding characteristics of binary complexes HFBe:FCl, R2Be:FCl, and FCl:N-base, and of ternary complexes HFBe:FCl:N-base and R2Be:FCl:N-base for R = H, F, Cl; N-base = NH3, NHCH2, NCH. Dramatic synergistic cooperative effects have been found between the Be···F beryllium bonds and the Cl···N halogen bonds in ternary complexes. The Cl···N traditional halogen bonds and the Be···F beryllium bonds in binary complexes become significantly stronger in ternary complexes, while the F-Cl bond weakens. Charge-transfer from F to the empty p(σ) orbital of Be leads to a bending of the XYBe molecule and a change in the hybridization of Be, which in the limit becomes sp(2). As a function of the intrinsic basicity of the nitrogen base and the intrinsic acidity of the Be derivative, the halogen-bond type evolves from traditional to chlorine-shared to ion-pair bonds. The mechanism by which an ion-pair complex is formed is similar to that involved in the dissociative proton attachment process. EOM-CCSD spin-spin coupling constants (1X)J(Cl-N) across the halogen bond in these complexes also provide evidence of the same evolution of the halogen-bond type.
已进行从头算MP2/aug'-cc-pVTZ计算，以研究二元配合物HFBe:FCl、R2Be:FCl和FCl:N-碱，以及三元配合物HFBe:FCl:N-碱和R2Be:FCl:N-碱（R = H、F、Cl；N-碱 = NH3、NHCH2、NCH）的结构、结合能和键合特征。在三元配合物中，已发现铍键Be···F与卤键Cl···N之间存在显著的协同合作效应。二元配合物中的Cl···N传统卤键和Be···F铍键在三元配合物中显著增强，而F-Cl键则减弱。电荷从F转移到Be的空p(σ)轨道导致XYBe分子弯曲以及Be的杂化变化，在极限情况下变为sp(2)。根据氮碱的固有碱性和Be衍生物的固有酸性，卤键类型从传统型演变为氯共享型再到离子对键型。这些配合物中通过卤键的EOM-CCSD自旋-自旋耦合常数(1X)J(Cl-N)也为卤键类型的相同演变提供了证据。
