Quinine-based (R)-tert-butylsulfinate 3 reacts with tris-lithiated bis-arylamide 2 to afford gram-quantities of optically pure (S*O)N(S*O) sulfoxide pincer ligand (R,R)-4. Deprotonation of (R,R)-4 and p-Tol-substituted analogue (S,S)-5 with MgPh₂ and BnK yields respective Mg and K amido-bis-sulfoxides 6–9. In Mg complexes 6 and 7, the sulfoxide functions are O-coordinated, thereby imparting a pronounced helicity to the ligand backbone. Transmetalation of 6 and 7 with [PdCl₂(NCPh)₂] affords the S,S-coordinated C₂-symmetric and the O,S-coordinated C₁-symmetric chlorido complexes 10 and 11, respectively, and reaction of potassium amides 8 and 9 with [PdCl(CH₃)(COD)] leads to methyl-palladium pincer complexes 12 and 13, respectively. The crystal structures of 6, 7, 12, and 13 reveal a chameleonic ligand system with predictable behavior: (R)-configured 4 induces pronounced λ backbone helicity in the O-coordinated Mg-complex and weaker δ helicity in S-coordinated Pd-complexes, while (S)-configured ligand 5 mirrors this stereochemistry. S-Coordination induces stronger, C₂-symmetric, steric crowding in the head-on quadrants compared to O-coordination. When (R,R)-4 is reacted with 2 equiv of [Pd(CH₃)₂(tmeda)], crystalline chiral Pd-sulfenate complex 16 forms by elimination of iso-butene and methane with inversion of configuration at the sulfenate S atom.

中文翻译：

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镁和钯的C _2-对称（SO）N（SO）亚砜钳配合物：通过不明确的S / O配位和分离手性钯-磺酸盐进行的螺旋转换

奎宁基（R）-叔丁基亚磺酸盐3与三锂化的双芳基酰胺2反应，得到克级的光学纯（S * O）N（S * O）亚砜钳形配体（R，R）-4。用MgPh ₂和BnK对（R，R）-4和对-Tol取代的类似物（S，S）-5进行质子化，分别得到Mg和K酰胺基双亚砜6 – 9。在镁络合物6和7中，亚砜官能团是O-配位的，从而赋予配体主链明显的螺旋性。用[PdCl ₂（NCPh）₂ ]对6和7进行重金属化分别提供S，S配位的C ₂对称和O，S配位的C ₁对称的氯配合物10和11，以及钾酰胺8的反应和9与[PdCl（CH ₃）（COD）]生成甲基-钯夹杂物12和13。的晶体结构6，7，12，和13揭示了具有可预测行为变色配体系统：（- [R ）-构型4个诱导显着λ骨干螺旋性在ø配位的Mg配合物和弱δ螺旋性在小号配位的Pd的（S）-构型的配体5反映了这种立体化学。与O配位相比，S配位在正面象限引起更强的C ₂对称空间拥挤。当（R，R）-4与2当量的[Pd（CH ₃）₂（tmeda）]反应，通过消除异丁烯和甲烷并在亚磺酸盐S原子上反转构型，形成结晶手性Pd-亚磺酸盐络合物16。