Two Triazole-Based Phosphine Ligands Prepared via Temperature-Mediated Li/H Exchange: Cu^I and Au^I Complexes and Structural Studies

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