Widmann Maximilian, Riesinger Christoph, Szlosek Robert, Balázs Gábor, Scheer Manfred
Department of Inorganic Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
Chemistry. 2024 Apr 2;30(19):e202304183. doi: 10.1002/chem.202304183. Epub 2024 Feb 13.
The electrophilic functionalization of the triple-decker sandwich complex [{CpMo}(μ,η-P)] (A) and its mono-oxidized counterpart [{CpMo}(μ,η-P)][SbF] (B) with reactive main-group electrophiles as well as radical scavengers is shown to be a reliable method for the selective functionalization of the hexaphosphabenzene ligand. Depending on the electrophile used, the regioselectivity of the functionalization can be adjusted. Using group 16 electrophiles, the trisubstituted compounds [{CpMo}{(μ,η-P)(μ,η-1,3-(SePh)-2-Br-P)}][TEF] (1), [{CpMo}(μ,η-P)(μ,η-1,2,3-(EPh)-P)][SbF] (E=S (2), Se (3)) as well as the side product [{CpMo}(μ,η-P)(μ,η-P(SPh))][SbF] (4) are obtained. By switching to phosphenium ions as group 15 electrophiles, the ring-inserted products [{CpMo}(μ,η-PR)][TEF] (R=Cy (5), Pr (6)) are isolated, showing an unprecedented PR structural motif. Furthermore, the reaction with MeOTf yields the dimeric [{CpMo}(1,4-Me-μ,η-P)(μ,η-P)][TEF] (7) as the first example of a complex featuring two interconnected cyclo-P middle deck ligands. Finally, by combination of the methylation step with PhSe, the mixed group 14/16 complex [{CpMo}{(μ,η-P)(μ,η1,2-(SePh)-3-Me-P)}][OTf] (8) is obtained.
三重夹心配合物[{CpMo}(μ,η-P)]（A）及其单氧化对应物[{CpMo}(μ,η-P)][SbF]（B）与活性主族亲电试剂以及自由基清除剂的亲电官能化反应被证明是一种对六磷苯配体进行选择性官能化的可靠方法。根据所使用的亲电试剂，可以调节官能化的区域选择性。使用第16族亲电试剂，可得到三取代化合物[{CpMo}{(μ,η-P)(μ,η-1,3-(SePh)-2-Br-P)}][TEF]（1）、[{CpMo}(μ,η-P)(μ,η-1,2,3-(EPh)-P)][SbF]（E = S（2），Se（3））以及副产物[{CpMo}(μ,η-P)(μ,η-P(SPh))][SbF]（4）。通过改用鏻离子作为第15族亲电试剂，可分离出环插入产物[{CpMo}(μ,η-PR)][TEF]（R = Cy（5），Pr（6）），其显示出前所未有的PR结构 motif。此外，与MeOTf反应生成二聚体[{CpMo}(1,4-Me-μ,η-P)(μ,η-P)][TEF]（7），这是具有两个相互连接的环-P中间层配体的配合物的首个实例。最后，通过将甲基化步骤与PhSe相结合，得到混合的第14/16族配合物[{CpMo}{(μ,η-P)(μ,η1,2-(SePh)-3-Me-P)}][OTf]（8）。
