并苯配体夹心体系Tin(n-acene)2的分子结构及金属-金属键的理论研究

Theoretical Study on Sandwich Complexes Ti_n(n-acene)_2 and Their Metal-Metal Bondings

基于B88P86/ZORA-TZP理论方法,研究并苯配体夹心多金属体系。优化Ti_n(n-acene)_2(n=2,3,4)的各种可能的分子结构,并考虑电子多重度,讨论分子的稳定性。根据分子轨道特性和三重态下的自旋密度分布等,分析各稳定构型的电子结构。计算Ti—Ti原子间的Mayer、Wiberg、Nalewajski-Mrozek键级指数,并辅以NPA、AIM计算的钛原子电荷,着重讨论Ti—Ti原子间的成键情况。所有Ti_n(n-acene)_2(n=2,3,4)体系中相邻金属原子间的Ti—Ti键基本都为单键,部分情况具有双键特性。D_(2h)Ti_3(An)_2(Singlet)中三个钛原子间存在明显的电子离域特性。此类分子有望用于电子或自旋电子输运方面的材料开发。

Based on the theoretical method B88P86/ZORA-TZP,the complexes with polymetal sandwiched between two polyacene ligands were studied in this paper.Possible structural configurations for Tin(n-acene)2were optimized by considering different spin multiplicities,and their relative stabilities were discussed.The molecular orbitals of stable singlet configurations and the spin density distributions of stable triplet ones were drawn to explain the electronic structures.The three types of bond indices,respectively based on Mayer,Wiberg and Nalewajski-Mrozek methods,were calculated,while two types of atomic charges,respectively based on NPA and AIM,were analyzed.Accordingly,the metal-metal bondings of each Ti-Ti pairs were emphasized.Each Ti-Ti bonds in all Tin(n-acene)2(n=2,3,4)systems were single bonds,with few exceptions of possible doubly bonding features.D2h Ti3(An)2(Singlet)carried good electron delocalization spreading through the three Ti atoms.This type of sandwiched complexes EMAC(extended matel atom chain)might be deserving of prospective experiment in the field of electronic or spintronic transport.