Facile Synthesis of Bifunctional Ligands using LiCH2PPh2NPh Obtained from [PhNH−PPh3 +][Br−]

The LiCH2PPh2NPh derivative 2 was cleanly prepared from the aminophosphonium salt [PhNH−PPh3 +][Br−] (1) and MeLi. After formation of the iminophosphorane PPh3NPh, nucleophilic displacement of one phenyl ring of the P atom by a methyl group occurred. This sequence was demonstrated to highly depend on the experimental conditions and on the substituent pattern at the nitrogen atom. Then, 2 was reacted with various electrophiles, among which phosphine chlorides, silyl chloride, stannyl chloride, and cyanophosphole, leading to bifunctional ligands. Depending on the electrophiles, the products were isolated either as the aminophosphonium salts or the iminophosphorane derivatives. All of these products were characterized by multinuclear NMR spectrocopy and in two cases by X-ray analysis. In particular, reaction of 2 with S8 gave rise to the thiolate derivative (LiSCH2PPh2NPh) (9), which was subsequently coordinated to Pd(II) and Ru(II) metal centers to give respectively [(PhNPPh2CH2S)Pd(PPh3)Cl] and [(PhNPPh2CH2S)Ru(p-cymene)Cl].