Synthesis, Structures, and Luminescence Properties of Interconvertible Au^I ₂Zn^II and Au^I ₃Zn^II Complexes with Mixed Bis(diphenylphosphino)methane and d‑Penicillaminate

The reaction of the digold­(I) complex [Au2(dppm) ­(d-pen)2]2– ([1]2–; dppm = bis­(diphenylphosphino)­methane and d-pen = d-penicillaminate) with Zn2+ in a 1:1 ratio gave the heterometallic AuI 2ZnII trinuclear complex [Au2Zn­(dppm)­(d-pen)2] ([3]), in which the Zn2+ ion is coordinated by [1]2– in an N2O2S2 octahedral geometry with the trans­(O) configuration, forming an 8-membered Au2ZnS2P2C metalloring. A similar reaction using the newly prepared and crystallographically characterized trigold­(I) complex [Au3(dppm)2(d-pen)2]− ([2]−) produced the AuI 3ZnII tetranuclear complex [Au3Zn­(dppm)2(d-pen)2]+ ([4]+), in which the Zn2+ ion is coordinated by [2]− in a similar octahedral geometry to form a Au3ZnS2P4C2 12-membered metalloring. Complex [3] was converted to [4]+ by treatment with [Au2(dppm)2]2+ in a 2:1 ratio, whereas [4]+ reverted to [3] upon treatment with a mixture of [Au­(d-pen)2]2– and Zn2+ in a 1:1 ratio, indicative of the facile insertion/removal of the [Au­(dppm)]+ moiety with retention of the geometry of the trans(O)-[Zn­(d-pen-N,O,S)2]2– unit. An analogous interconversion that requires the insertion/removal of the [Au­(dppm)]+ moiety was also recognized between [1]2– and [2]−. NMR spectroscopy revealed that [4]+ is in equilibrium with [3] and [Au2(dppm)2]2+ in solution, the ratio of which is largely dependent on the solvent polarity. The luminescence properties of these complexes were also investigated, revealing the importance of the intramolecular aurophilic interaction, as well as the ZnII coordination, for enhancement of the emission quantum efficiencies.二金(I)配合物[Au₂(dppm)(d-pen)₂]²⁻（记为[1]²⁻；其中dppm为双(二苯基膦)甲烷（bis(diphenylphosphino)methane），d-pen为d-青霉胺（d-penicillaminate））以1:1的摩尔比与Zn²⁺反应，得到异金属AuI₂ZnII三核配合物[Au₂Zn(dppm)(d-pen)₂]（记为[3]）。该配合物中，Zn²⁺离子被[1]²⁻以N₂O₂S₂八面体配位构型结合，且呈现反式(O)构型，形成8元Au₂ZnS₂P₂C金属环。 使用新制备并经晶体学表征的三金(I)配合物[Au₃(dppm)₂(d-pen)₂]⁻（记为[2]⁻）进行类似反应，得到AuI₃ZnII四核配合物[Au₃Zn(dppm)₂(d-pen)₂]⁺（记为[4]⁺）。其中Zn²⁺离子被[2]⁻以相似的八面体配位方式结合，形成Au₃ZnS₂P₄C₂十二元金属环。 配合物[3]可通过以2:1的摩尔比与[Au₂(dppm)₂]²⁺反应转化为[4]⁺；而[4]⁺与[Au(d-pen)₂]²⁻和Zn²⁺按1:1的摩尔比混合处理后，可重新转化为[3]，这表明[Au(dppm)]⁺单元的插入/移除可在保持trans(O)-[Zn(d-pen-N,O,S)₂]²⁻单元几何构型的条件下轻松实现。 在[1]²⁻与[2]⁻之间也观察到了类似的、需要[Au(dppm)]⁺单元插入/移除的互变过程。核磁共振波谱研究表明，[4]⁺在溶液中与[3]和[Au₂(dppm)₂]²⁺处于平衡状态，其平衡比例很大程度上取决于溶剂的极性。 本研究还对这些配合物的发光性能进行了探究，结果揭示了分子内亲金作用以及ZnII配位对于提升发射量子效率的重要性。