新型反夹心配合物特性及潜在应用的理论研究

Inverse sandwich complexes have the properties to stabilize the low-valent elements, high-spin states or special bonds passing through the ligand. Currently the research on this field is still in its infancy, and several key issues remain to be resolved. One of the most important issues is how the interaction between the ligand and the metal cores effects on the properties of inverse sandwich complexes. In this topic, we will perform the following investigations: (1)Inverse sandwich complexes with metal-metal bond passing through the ligand. In this case, the metals besides the ligand forms the metal-metal bond, the middle hole of the ligand provides the space for the overlap of the bonding orbital, and the interaction between the metal cores and the ligand would stabilize the inverse sandwich structures. The systems of Xm[M–CnHn–M]Xm (M=Sc~V, Y~Nb; n=4~8; X=H,Cp,F~I, O~Se, N~As; m=1~3) will be emphatically studied. (2) Inverse sandwich complexes with high spin state. In this case, the ligand blocks the bonding between the metal cores, and consequently produces two relatively independent spin centers, and results in the ground state to be singlet-diradicals or high spin state. The systems of [M(Nacnac)]2(μ-CnHn) (M=V~Ni, Nb~Pd; n=4~8) will be emphatically studied. Besides, the potential applications for building the function materials of the inverse sandwich complexes are also studied.

反夹心配合物具有稳定低价元素、高自旋态或特殊成键等性能。目前该领域的研究处于起步阶段，一些关键问题尚待解决，其中最为关键的是金属与配体的相互作用如何影响配合物的性能。本课题将重点研究：(1)含穿透配体的金属-金属键的反夹心配合物。即配体两侧金属原子穿透配体成键，配体中间的孔道为成键提供了轨道重叠的空间，配体与金属的相互作用对反夹心结构起到稳定作用。主要研究Xm[M–CnHn–M]Xm (M=Sc~V, Y~Nb; n=4~8; X=H, Cp, F~I,O~Se, N~As; m=1~3)等。(2)高自旋态的反夹心配合物。配体作为一种“阻碍”使两侧金属核心无法成键，进而形成两个相对独立的自旋中心，使反夹心配合物呈现高自旋态的特征。主要研究[M(Nacnac)]2(μ-CnHn) (M=V~Ni, Nb~Pd; n=4~8)等。此外，课题也将对反夹心配合物构建功能材料等潜在应用进行研究。

为探讨金属与配体的相互作用对反夹心配合物性能的影响，本课题重点研究了以下内容：(1)设计具有穿透配体的V-V键及平面正方形芳香性Si4配体的反夹心配合物[VCl]2[Si4R4] (R = H, CH3, SiH3)。该Si4配体的Si-Si之间不具有σ键，仅具有芳香性π键。V-V键限制了V与Si4环相对位置，从而使Si4环具有这种特殊成键。(2)设计螺环金属芳香性配体(C10H10M)2‒ (M = Ni, Pd, Pt)。反夹心配合物C10H10M)Li2可使配体稳定，此外[(C10H10M)Li2]n多聚物的构建在材料化学领域也有潜在价值。(3)设计高自旋多重度的反夹心配合物[M(AIP)]2(C4H4) (M = V, Cr)。该类体系可达到七重态、九重态的高自旋多重度。在形成芳香性配体时，金属原子破坏原有孤对电子向C4H4提供单电子，使单电子数量增加而导致高自旋。(4)设计异核反夹心配合物[M(AIP)](C5H5)[M'(AIP)] (M, M' = V, Cr, Mn)。该体系存在多稳态构型，自旋交叉能垒较低。根据自旋态的不同，V、Cr、Mn原子可出现+1和+2价的可变价态。自旋交叉和价态互变过程使其具有成为分子磁性材料的潜能。总体而言，本项目设计了几类具有特殊电子构型及潜在应用价值的反夹心配合物。