Two Triazole-Based Phosphine Ligands Prepared via Temperature-Mediated Li/H Exchange: CuI and AuI Complexes and Structural Studies

The kinetically favored triazole-based phosphine 1-(2-(diphenylphosphino)­phenyl)-4-phenyl-1H-1,2,3-triazole (2, L1) and its thermodynamically preferred isomer, 5-(diphenylphosphino)-1,4-diphenyl-1H-1,2,3-triazole (3, L2), were obtained by the temperature-controlled lithiation of 2-bromotriazole followed by the reaction with chlorodiphenylphosphine. The structures of phosphines 2 and 3 were determined by X-ray diffraction. Upon reaction with late transition-metal derivatives (CuI, AgI, and AuI), phosphines 2 and 3 form complexes with monodentate (CuI, AgI, and AuI; κ1-P), chelate (CuI; κ2-P,N), bridged bidentate (CuI; μ2-P,N), and tridentate (CuI; μ2,κ2-P,N,N) modes of coordination. Reactions with copper­(I) halides produced mono-, di-, and tetranuclear complexes, whereas the reaction of 2 with [Cu­(NCCH3)4]­BF4 yielded the binuclear complex [Cu2(CH3CN)2{o-Ph2P­(C6H4)­{1,2,3-N3C­(Ph)­C­(H)}-μ-(κ-P,κ-N),κ-N}2]­(BF4)2 (10) with the ligand acting as a six-electron donor involving phosphorus and two triazole nitrogen atoms. The copper complexes of 2 and 3 containing rhomboid Cu2X2 units, [(Cu)2(μ-X)2{o-Ph2P­(C6H4)­{1,2,3-N3C­(Ph)­C­(H)}-κ-P}2] (4, X = Cl; 5, X = Br), on treatment with 1,10-phenanthroline and 2,2′-bipyridine gave mixed-ligand complexes of the type [(CuX)­(N∩N-κ2-N,N)­{o-Ph2P­(C6H4)­{1,2,3-N3C­(Ph)­C­(H)}-κ-P}] (N∩N = 1,10-phen and 2,2′-bipy; X = Cl, Br, and I).