Palladium(II) complexes featuring a mixed phosphine-pyridine-iminophosphorane pincer ligand: synthesis and reactivity.

摘要: An original mixed ligand (labelled L) of formula PPh2-CH2-Pyr-CH2-N[double bond, length as m-dash]PPh3, combining a pyridine core with phosphine and iminophosphorane, was synthesised. Its coordination palladium(II) centers studied. With [Pd(COD)Cl2], cationic complex [LPdCl](Cl) 1, where L is coordinated in the pincer mode, obtained. Chloride abstraction silver salt presence generated dicationic [LPd(py)](BF4)2 (2). When reacting base such potassium hexamethyldisilazane (KHMDS), 1 gave neutral 3 [L*PdCl], wherein benzylic position alpha to selectively deprotonated, which induced dearomatisation ring. A similar [L*Pd(CH3)] (4) obtained upon reaction [Pd(CH3)2(TMEDA)] Lvia departure methane. Neutral complexes deprotonated yielded deuterated methanol corresponding complex, showing that protonation reversible this ligand. Finally, attempting dealkylate 4 using B(C6F5)3, an unexpected zwitterionic borated 5, resulting from formation C-B bond restoration aromatic character pyridine, isolated. Interestingly, when metal introduced after interacted borane reagent, another palladium formed, namely, [LPdMe][MeB(C6F5)3], originating methyl abstraction.