Triazolyl-phosphole and triazolyl-azaphosphole: synthesis, transition metal complexes and catalytic studies.

Phosphole and azaphosphole derivatives with triazole functionalities, [C6H5{1,2,3-N3CC6H4C(PPh)}] (L1) and [C6H4{1,2,3-N3C(Ph)C(PPh)}] (L2) were synthesized by reacting [(C6H5)(1,2,3-N3C = CH-o-Br-C6H4)] and [(o-Br-C6H4)(1,2,3-N3C = CHC6H5)] with nBuLi followed by the addition of dichlorophenylphosphine. The reactions of L1 and L2 with an excess of 30% H2O2 afforded phosphole oxides [C6H5{1,2,3-N3CC6H4C(P(O)Ph)}] (L1O) and [C6H4{1,2,3-N3C(Ph)C(P(O)Ph)}] (L2O) as white crystalline solids. Stoichiometric reactions of L1 and L2 with [Ru(η6-p-cymene)Cl2]2 in CH2Cl2 yielded [RuCl2(η6-p-cymene)(L1-κ1-P)] (1) and [RuCl2(η6-p-cymene)(L2-κ1-P)] (2), respectively. Similar reactions of L1 and L2 with [Pd(COD)Cl2] and [Pd(η3-C3H5)Cl]2 produced the corresponding complexes, trans-[PdCl2(L1-κ1-P)2] (3), trans-[PdCl2(L2-κ1-P)2] (4), [Pd(η3-C3H5)Cl(L1-κ1-P)] (5), and [Pd(η3-C3H5)Cl(L2-κ1-P)] (6). Treatment of L1 with [AuCl(SMe2)] in dichloromethane afforded [AuCl(L1-κ1-P)] (7). Ruthenium complex 1 showed moderate to good catalytic activity towards benzylic C-H oxidation, and the proposed mechanism for the catalysis was supported by spectroscopic data.