Lanthanide(II)−Alkali Sandwich Complexes with Cation−Arene π Interactions: Synthesis, Structure, and Solvent-Mediated Redox Transformations

We successfully prepared and characterized two novel sandwich complexes [(LPh)2LnII{K(Et2O)}2] (Ln = Sm (2), Yb (3), LPh = [Ph2Si(NAr)2]2− (Ar = 2, 6-Pri2C6H3)) with cation−π interactions. The divalent samarium complex reacts with azobenzene and obtain rare dimeric samarium clusters [(LPh)2Sm2(μ-η2:η2-N2Ph2)2{K(THF)2}2] (4) and tetrameric [(LPh)Sm4(μ−η2:η2-N2Ph2)3(μ3-NPh)2(THF)3] (5). On the other hand, the reaction of complex 2 and α-diimines ArNCR−CRNAr (DAD, R = H, Me) produce a polymeric [(LPh)Sm{(ArN)RCCR(NAr)}K]n (R = H (6), Me (7)) assembled from cation−π interactions and a [{(LPh)2Sm}{K(THF)6}] byproduct (8). In particular, crystallographic analyses of 6 and 7 revealed that both complexes are samarium(III) stabilized by the DAD dianionic units in a σ2-enediamide manner. Complexes 2−8 have been fully characterized by elemental analyses and X-ray crystallography.

我们成功制备并表征了两种具有阳离子-π相互作用的新型夹心配合物[(LPh)₂LnⅡ{K(Et₂O)}₂]（其中Ln = Sm（2）、Yb（3），LPh = [Ph₂Si(NAr)₂]²⁻，Ar = 2,6-二异丙基苯基）。二价钐配合物（配合物2）与偶氮苯反应，得到罕见的二聚钐簇[(LPh)₂Sm₂(μ-η²:η²-N₂Ph₂)₂{K(THF)₂}₂]（4）与四聚体[(LPh)Sm₄(μ−η²:η²-N₂Ph₂)₃(μ₃-NPh)₂(THF)₃]（5）。另一方面，配合物2与α-二亚胺ArN=CR−CR=NAr（DAD，R = H、Me）反应，生成由阳离子-π相互作用组装得到的聚合物[(LPh)Sm{(ArN)RC=CR(NAr)}K]ₙ（R = H（6）、Me（7）），以及副产物[{(LPh)₂Sm}{K(THF)₆}]（8）。尤为值得注意的是，对配合物6和7的晶体结构分析显示，二者均为以σ²-烯二胺配位模式的二阴离子DAD单元稳定的三价钐配合物。配合物2~8均通过元素分析与单晶X射线衍射完成了全面表征。