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C4H42-、C5H5-(Cp-)及C6H6(Ar)等有机配体可以与过渡金属形成典型的三明治夹心化合物.作为CH的等电子体,P可以取代CH与过渡金属形成混合型三明治配合物,例如:CpNiP3,CpFeP5,[CpMPnMCp]等.2002年,Schleyer等首次成功地合成了以η5-P5-为配体的不含碳的无机三明治配合物[P5TiP5]2-;2007年,Chen等采用密度泛函方法预测了含P4四元环的[P4MP4]n-三明治结构.本文采用密度泛函和从头计算方法首次系统地研究了含η3-P3-和η3-As3-三元环配体的过渡金属三明治配合物D3d[E3ME3]2-(E=P,As;M=Ni,Pd,Pt)(图1),对该系列化合物进行了结构优化、频率分析、自然轨道分析和光谱性质预测.结果表明,三元环状P3-和As3-与五元环状P5-和As5-具有类似的芳香性,可能作为新颖配位形成一大类过渡金属夹心化合物.[E3ME3]2-满足18电子规则,交错型单重态D3d[E3ME3]2-是该七原子体系的全局极小,而重叠型单重态D3h[E3ME3]2-在能量上略高(>2.0kcal/mol),其他二维和三维结构则远非稳定(>24kcal/mol).作为体系的全局极小,D3d[E3ME3]2-是在实验上可能合成的最小无机三明治夹心结构.在[E3ME3]2-系列配合物中,配位中心M携带的电荷为+0.07|e|～+0.27|e|,Wiberg键级为1.84～2.22;配体E原子携带的电荷为-0.35|e|～-0.38|e|,Wiberg键级为2.93～2.98.配体原子间以单键(WBIE-E=1.03-1.07),配体E和配位中心M间的Wiberg键级为WBIM-E=0.31-0.37,体现典型的配位成键特点.显然,与实验已知的[P5TiP5]2-类似,在[E3ME3]2-体系中配位中心M向配体E3发生了部分电荷转移,E3三元环表现为电子受体.轨道分析表明,该夹心化合物体系存在典型的离域π键(图1).体系存在较大NICS(-18.1～-24.8ppm),表明其芳香性本质.引进Li+阳离子可以有效稳定[E3ME3]2-二价阴离子,形成含交错型Cs[E3ME3]Li-和C2h[E3ME3]Li2.Cs[E3ME3]Li-的第一计算电子剥离能介于2.7～2.9eV,位于355nm激发光能量(3.496eV)范围之内.
Organic ligands such as C4H42-, C5H5- (Cp-), and C6H6 (Ar) can form typical sandwich sandwich compounds with transition metals. As CH isomers, P can replace CH with transition metals to form mixed sandwich complexes, For example: CpNiP3, CpFeP5, [CpMPnMCp], etc. In 2002, Schleyer et al. Successfully synthesized the non-carbon containing inorganic sandwich complex [P5TiP5] 2- with η5-P5- as ligand for the first time. Density functional method is used to predict the [P4MP4] n-sandwich structure with P4 four-membered rings.In this paper, we first systematically studied the [P4MP4] n-sandwich structure with η3-P3- and η3-As3- Structural optimization, frequency analysis, orbital analysis and spectral property prediction of the transition metal sandwich complexes D3d [E3ME3] 2- (E = P, As; M = Ni, Pd, Pt) The results show that the ternary cyclic P3- and As3- have the similar aromaticity with the five-membered cyclic P5- and As5-, which may form a novel class of transition metal sandwich compounds as novel coordination [E3ME3] 2- Electronic rules, the staggered singlet D3d [E3ME3] 2- is the global minimum of the seven-atom system, and the overlapping singlet D3h [E3ME3] 2- Slightly higher (> 2.0 kcal / mol), the other two-dimensional and three-dimensional structure is far from stable (> 24 kcal / mol) .As the global minimum of the system, D3d [E3ME3] 2- is the experimentally possible synthesis of the smallest inorganic sandwiches In the [E3ME3] 2-series complexes, the coordination center M carries a charge of +0.07 | e | ~ + 0.27 | e |, and the Wiberg bond order is 1.84-2.22. The charge carried by the ligand E atom is -0.35 | e | ~ -0.38 | e |, Wiberg bond order is 2.93 ~ 2.98. The Wiberg bond order between the ligand atoms is single bond (WBIE-E = 1.03-1.07), ligand E and coordination center M Is WBIM-E = 0.31-0.37, which shows the characteristic of typical coordination and bonding.Obviously, similar to experimentally known [P5TiP5] 2-, coordinate center M to [E3ME3] 2- system occurred to ligand E3 Some charge transfer, E3 ternary ring showed electron acceptor.The orbital analysis showed that there is a typical delocalized π bond (Figure 1) .The system has a large NICS (-18.1 ~ -24.8ppm), indicating that Aromatic nature. The introduction of Li + cations can effectively stabilize [E3ME3] 2-dianion to form the first calculated electron stripping energy containing intercalated Cs [E3ME3] Li- and C2h [E3ME3] Li2.Cs [E3ME3] Li- At 2.7 ~ 2.9eV, 355nm excitation light energy (3.496eV) Within the scope.