Studies on Photo-excited State valence Tautomerism of Multinuclear Metal Complexes by X-ray Crystallographic Analyses

虽然碘桥铂（II），（IV）双二胺配合物的合成和结晶已经进行，没有良好的晶体样品的光激发晶体学研究成功地获得。相反，光激发态X-射线衍射研究的发光卤素桥接的铜（I）聚合物配合物已取得进展。[Cu_2X_2（PPh_3）_2L]∞（X=I，Br，Cl; L=联吡啶或吡啶）是由{Cu_2X_2}菱形单元通过二亚胺配体桥接而成的无限链状结构。发射带的起源主要归属于Cu（I）到配体电荷转移（MLCT）和卤素到配体（XLCT）激发态。碘配合物[Cu_2I_2（PPh_3）_2（bpy）]_∞的X射线单晶衍射实验表明，在{Cu_2I_2}面内，两个碘原子相互靠近。在[Cu_2I_2（PPh_3）_2（pyz）]∞中，金属原子和卤素原子的运动也是同样的方式。而对于一个具有相同{Cu_2I_2}的离散配合物[Cu_2I_2（PPh_3）（pyz）_2]，则表明晶体中{Cu_2I_2}核心的很小一部分发生了转动，键的膨胀或收缩很小。在另一个不连续的配合物[Cu_2I_2（PPh_3）（Ph-py）_2]中，没有发现明显的几何畸变，但却显示出强烈的发光，并归属于配体π-π* 过渡态的不同性质。在{Cu_2I_2}骨架中，激发态结构的变化与基态几何结构之间存在着一些显著的相关性，这也与它们的发光性质有关。

Although syntheses and crystallization of iodo-bridged platinum(II),(IV) bis-diamine complex have been performed, no good crystal sample for photo-excited crystallographic studies was successfully obtained. Instead, photo-excited state X-ray diffraction studied for luminescent halogen-bridged copper(I) polymer complexes have been progressed. Luminescent dicopper(I) complexes [Cu_2X_2(PPh_3)_2L]∞(X=I, Br, Cl; L=bipyridine or pyradine) consist of {Cu_2X_2} rhombic units, which are bridged by diimine ligands constructing an infinite chain structure. The origin of emission bands are assigned mainly to a Cu(I) to ligand charge transfer (MLCT) and a halogen to ligand (XLCT) excited states. Single crystal X-ray diffraction experiments under photo-illumination for the iodine-complex [Cu_2I_2(PPh_3)_2(bpy)]∞ have shown that two iodine atoms are moved toward close to each other within the {Cu_2I_2} plane. The same manner in the motion of the metal and halogen atoms have found in [Cu_2I_2(PPh_3)_2(pyz)]∞. While in the case of a related discrete complex [Cu_2I_2(PPh_3)(pyz)_2] which has the same {Cu_2I_2} indicate that a very small portion of {Cu_2I_2} core in the crystal is rotated with little bond enlarge or shrinkage. There are no significant geometrical distortion has found in another discrete complex [Cu_2I_2(PPh_3)(Ph-py)_2] which shows intense luminescence which is assigned to a different nature as a ligand π-π* transition state. Some significant correlations have been revealed between excited-state structure changes and ground state geometries in the {Cu2I2} framework, which are also related with their luminescent properties.