1,2,3-Triazole based ligands with phosphine and pyridine functionalities: synthesis, PdII and PtII chemistry and catalytic studies

This manuscript describes the syntheses of pyridine appended triazole-based mono- and bisphosphines, [o-Ph2P(C6H4){1,2,3-N3C(Py)C(H)}] (2), [o-Br(C6H4){1,2,3-N3C(Py)C(PPh2)}] (3), [C6H5{1,2,3-N3C(Py)C(PPh2)}] (4), [Ph2P(C6H4){1,2,3-N3C(Py)C(PPh2)}] (5) and [3-Ph2P-2-{1,2,3-N3C(Ph)C(PPh2)}C5H3N] (6), their palladium and platinum chemistry and catalytic applications. These ligands upon treatment with [M(COD)Cl-2] (M = Pd or Pt) yielded complexes with different coordination modes, depending on the reaction conditions. Both kappa(2)-P,N and kappa(2)-P,P coordination modes were observed in many of the complexes indicating the ambidentate nature of these ligands. Monophosphine 2 in the presence of a base afforded rare fused-5,6-membered PCN pincer complexes [MCl{o-Ph2P(C6H4){1,2,3-N3C(Py)C(H)}}-kappa(3)-P,C,N] (7, M = Pd; 8, M = Pt), whereas the reactions of 4 with [M(COD)Cl-2] (M = Pd, Pt) produced kappa(2)-P,N chelate complexes [MCl2{C6H5{1,2,3-N3C(Py)C(PPh2)}-kappa(2)-P,N}] (9, M = Pd; 10, M = Pt). Similar reactions of 5 and 6 resulted in kappa(2)-P,P chelate complexes [MCl2{{3-Ph2P-2-{1,2,3-N3C(Ph)C(PPh2)}C5H3N}-kappa(2)-P,P}] (11, M = Pd; 12, M = Pt) and [MCl2{3-Ph2P-2-{1,2,3-N3C(Ph)C(PPh2)}C5H3N}-kappa(2)-P,P}] (13, M = Pd; 14, M = Pt), respectively. The palladium(ii) complexes have shown excellent catalytic activity in the alpha-alkylation reaction of acetophenone derivatives.

Automated summary

This manuscript describes the syntheses of pyridine appended triazole-based mono- and bisphosphines and their palladium and platinum chemistry and catalytic applications. Different coordination modes were observed in the complexes depending on the reaction conditions, indicating the ambidentate nature of these ligands. The palladium complexes showed excellent catalytic activity in the alpha-alkylation reaction of acetophenone derivatives.