Copper and Silver Complexes of o-Ph2PC6H4C(O)N(H)C9H6N: Synthesis and Catalytic Applications of CuI Complexes.

In this article, synthesis of an amide-based PNN ligand o-Ph2PC6H4C(O)N(H)C9H6N(1), its oxide o-Ph2P(O)C6H4C(O)N(H)C9H6N (2), and CuI, CuII, and AgI complexes are described. Reactions of 1 with CuIX resulted in both monometallic [CuX{(o-Ph2P)C6H4C(O)N(H)C9H6N}2] (3, X = Cl; 4, X = Br; 5, X = I) and bimetallic complexes [{Cu(μ2-X)(o-Ph2P)C6H4C(O)N(H)C9H6N}2] (6, X = Cl; 7, X = Br; 8, X = I). Similar reactions of compound 2 with CuIX yielded the (P = O)NN coordinated complexes [{Cu(μ2-X)(o-Ph2P(O))C6H4C(O)NC9H6N}2] (9, X = Cl; 10, X = Br; 11, X = I). Reactions of 1 with AgX (X = Br, I) afforded [{(o-Ph2P)C6H4C(O)N(H)C9H6N}2AgX] (12, X = Br; 13, X = I). Monometallic complexes 3, 4, and 5 are insoluble in most common organic solvents. A shorter Cu1-Cu1' distance of 2.5372(5) Å in 8 indicates the presence of Cu···Cu interactions. Copper complex 8 showed good catalytic activity toward the heteroannulation reaction of 2-halophenols and terminal acetylenes to give benzofurans. Controlled experiments indicate that the reaction is homogeneous and does not follow the radical pathway.