Synthesis, Structure, and Stereochemistry of Trinuclear Metal Complexes Formed from the Phosphorus-Based Achiral Tripodal Ligand {P(S)[N(Me)NCHC₆H₄-<i>o</i>-OH]₃} (LH₃): Luminescent Properties of L₂Cd₃·2H₂O

Neutral trinuclear metal complexes L2Cd3·2H2O, L2Mn3·MeOH, and L2Zn3·MeOH were isolated in the reaction between the phosphorus-centered achiral tris(hydrazone) P(S)[N(Me)NCHC6H4-o-OH]3 (LH3) and the corresponding divalent metal ions. The trinuclear complexes contain two equivalent terminal metal ions (Mt) and a central metal ion (Mc). The ligand encapsulates Mt in a facial N3O3 coordination environment. From the coordination sphere of the two terminal metal ions a pair of phenolic oxygen atoms further coordinate to the central metal ion. The coordination requirements of Mc are completed by the solvents of coordination. The achiral trianionic tripodal ligand (L)3- induces chirality in the metal complexes. This results in a Δ (clockwise) or Λ (anticlockwise) configuration for the terminal metal ions. The enantiomeric complexes 2−4 (Δ−Δ or Λ−Λ) crystallize as racemic compounds. The supramolecular structures of 2−4 reveal chiral recognition in the solid-state; every molecule with the Δ−Δ configuration interacts stereospecifically, through C−H···SP bonds, with two Λ−Λ molecules to generate a one-dimensional polymeric chain. Photophysical studies of the diamagnetic trinuclear complexes reveal that the tricadmium complex is luminescent in the solid state as well as in solution. In contrast LH3 and L2Zn3·MeOH are nonluminescent.以磷中心非手性三腙P(S)[N(Me)N=CHC₆H₄-o-OH]₃（LH₃）与相应二价金属离子进行反应，分离得到中性三核金属配合物L₂Cd₃·2H₂O、L₂Mn₃·甲醇（MeOH）以及L₂Zn₃·甲醇（MeOH）。该类三核配合物包含两个等价的端基金属离子（Mt）与一个中心金属离子（Mc）。配体将Mt包裹于面式N₃O₃配位环境中；两个端基金属离子的配位球内，一对酚氧原子可进一步与中心金属离子配位。中心金属离子Mc的配位需求由配位溶剂补足。非手性三阴离子三脚架型配体（L）³⁻可赋予该金属配合物手性，使得端基金属离子形成Δ（顺时针）或Λ（逆时针）构型。对映体配合物2~4（Δ−Δ或Λ−Λ）以消旋化合物形式结晶。2~4的超分子结构展现出固态手性识别现象：每一个Δ−Δ构型的分子可通过C−H···S=P键与两个Λ−Λ分子发生立体特异性相互作用，进而形成一维聚合物链。对该类抗磁性三核配合物的光物理研究表明，三镉配合物在固态与溶液态下均具有发光性能；与之相反，LH₃与L₂Zn₃·甲醇（MeOH）则不具有发光性。