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

虽然已经合成和结晶了碘桥联的铂(II)、(IV)双二胺配合物，但还没有成功地获得用于光激发结晶学研究的良好的晶体样品。相反，发光卤素桥联铜(I)聚合物配合物的光激发态X射线衍射研究取得了进展。发光双铜(I)配合物[Cu2X2(PPh3)2L]∞(X=I，BrCl2；L=联吡啶或吡啶)由{Cu2X2}菱形单元组成，这些菱形单元由形成无限链状结构的二亚胺配体桥联。发射带的来源主要是铜(I)到配体的电荷转移(MLCT)和卤素到配体(XLCT)的激发态。对碘配合物[Cu2I_2(PPh_3)_2(Bpy)]∞的光致单晶X射线衍射实验表明，在{Cu2I_2}面内，两个碘原子相互靠近。在[Cu2I2(PPh3)2(PYZ)]∞中，金属原子和卤素原子的运动方式是相同的。而对于具有相同{Cu2I2}的相关离散络合物[Cu2I2(PPh3)(PYZ)2]，则表明晶体中有很小一部分{Cu2I2}核心发生旋转，键几乎没有扩大或收缩。另一种离散型配合物[Cu2I2(PPh_3)(Ph-py)_2]没有发现明显的几何失真，它显示出不同性质的强烈发光，作为配体π-π*过渡态。在{Cu2I2}骨架中，激发态结构的变化与基态几何构型之间存在着显著的关联，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.