Chiral (SO)–N–(SO) Sulfoxide Pincer Complexes of Mg, Rh, and Ir: N–H Activation and Selective Sulfoxide Reduction upon Ligand Coordination

Multigram quantities of the optically pure amino–bis-sulfoxide ligand (S,S)-bis­(4-tert-butyl-2-(p-tolylsulfinyl)­phenyl)­amine ((S,S)-3) are accessible by in situ lithiation of bis­(2-bromo-4-tert-butylphenyl)­amine (1) followed by a nucleophilic displacement reaction with Andersen’s sulfinate 2. Deprotonation of (S,S)-3 with MgPh2 yields the magnesium amido–bis-sulfoxide salt (S,S)-4 quantitatively. Metathetical exchange of (S,S)-4 with [RhCl­(COE)2]2 affords the optically pure pseudo-C2-symmetric Rh­(I)–amido bis-sulfoxide pincer complex mer-(R,R)-[Rh­(bis­(4-(tert-butyl)-2-(p-tolylsulfinyl)­phenyl)­amide)­(COE)] (mer-(R,R)-5). This complex reacts with 3 equiv of HCl to give the facial Rh­(III) complex fac-(S,R,R)-[Rh­(bis­(4-(tert-butyl)-2-(p-tolylsulfinyl)­phenyl)­amine)­Cl3] (fac-(S,R,R)-6), in which one of the sulfoxide functions has been reduced to the sulfide and in which the resulting sulfoxide–sulfide–amine ligand is facially coordinated. The same complexes 5 and 6 form in a 1:2 ratio in a disproportionation reaction when [RhCl­(COE)2]2 is treated with 2 equiv of neutral ligand 3. N–H activation is directly observed in the reaction of [IrCl­(COE)2]2 with 3, affording the amido–hydrido–Ir­(III) complex [Ir­(bis­(4-(tert-butyl)-2-(p-tolylsulfinyl)­phenyl)­amide)­(Cl)­(H)­(COE)] (8).

可通过对双(2-溴-4-叔丁基苯基)胺（bis(2-bromo-4-tert-butylphenyl)amine，1）进行原位锂化，随后与安德森亚磺酸盐（Andersen’s sulfinate）2发生亲核取代反应，获得数克级光学纯的氨基双亚砜配体( S,S )-双(4-叔丁基-2-(对甲苯亚磺酰基)苯基)胺（( S,S )-3）。用二苯基镁（MgPh₂）对( S,S )-3进行脱质子处理，可定量得到酰胺基双亚砜合镁盐( S,S )-4。将( S,S )-4与二[双(环辛烯)氯化铑(I)]二聚体（[RhCl(COE)₂]₂）进行复分解交换反应，可得到光学纯的假C₂对称（pseudo-C₂-symmetric）铑(I)-酰胺基双亚砜钳形配合物经式-(R,R)-[Rh(双(4-叔丁基-2-(对甲苯亚磺酰基)苯基)酰胺)(环辛烯)]（mer-(R,R)-5）。该配合物与3当量的氯化氢反应，得到面式铑(III)配合物fac-(S,R,R)-[Rh(双(4-叔丁基-2-(对甲苯亚磺酰基)苯基)胺)三氯化物]（fac-(S,R,R)-6），其中一个亚砜官能团被还原为硫醚，所得的亚砜-硫醚-胺配体以面式方式配位。当二[双(环辛烯)氯化铑(I)]二聚体与2当量的中性配体3反应时，会发生歧化反应，以1:2的摩尔比生成相同的配合物5和6。在二[双(环辛烯)氯化铱(I)]二聚体与3的反应中，可直接观察到N-H键活化（N–H activation），生成酰胺基-氢合铱(III)配合物[Ir(双(4-叔丁基-2-(对甲苯亚磺酰基)苯基)酰胺)(Cl)(H)(COE)]（8）。