Gold complexes of 3,4-bis(diphenylphosphinoamino)toluene and 1,2-bis(diphenylphosphinoamino)benzene. A comparative study†

Abstract

The reaction of the diphosphines 3,4-(NHPPh₂)₂MeC₆H₃ and 1,2-(NHPPh₂)₂C₆H₄ with gold(I) and gold(III) substrates such as [Au(C₆F₅)_n(tht)] or [Au(tht)₂]X in various molar ratios led to the dinuclear [RC₆H₃{NHPPh₂Au(C₆F₅)_n}₂] (R = Me, n = 1 1 or 3 6; R = H, n = 1 2 or 3 7) and [{RC₆H₃(NHPPh₂)₂Au}₂][O₃SCF₃]₂ (R = Me 3 or H 5) or the mononuclear [MeC₆H₃(NHPPh₂)₂Au(C₆F₅)₃] 8 and [{MeC₆H₃(NHPPh₂)₂}₂Au] X (X = O₃SCF₃ 4a or ClO₄ 4b) complexes, showing different selectivity depending on the phosphine. Reaction of 8 with gold(1) compounds gave the mixed neutral gold(I)–gold(III) [MeC₆H₃(NHPPh₂)₂Au(C₆F₅)₃AuX] (X = Cl 9 or C₆F₅ 10) derivatives. When the pentafluorophenyl gold precursors are treated with the disulfides 3,4-(NHPPh₂S)₂MeC₆H₃ and 1,2-(NHPPh₂S)₂C₆H₄ only the dinuclear complexes [RC₆H₃(NHPPh₂SAu(C₆F₅)_n)₂] (R = Me, n = 1 11 or 3 12; R = H, n = 1 13 or 3 14) are obtained. Mononuclear cationic complexes [RC₆H₃(NHPPh₂S)₂Au(C₆F₅)₂]ClO₄ (R = Me 15 or H 16) have also been obtained by reaction of the phosphinosulfides with the gold(III) precursor [Au(C₆F₅)₂(OEt₂)₂]ClO₄. The addition of the deprotonating agent NBu₄(acac) to 1, 2 and 7 removes one aminic proton, yielding the dinuclear anionic complexes [NBu₄][RC₆H₃{NHPPh₂Au(C₆F₅)_n}{NPPh₂Au(C₆F₅)_n}] (R = Me, n = 1 17; R = H, n = 1 18 or 3 19). Addition of the aurating agent [Au(OClO₃)(PPh₃)] to complex 19 led to the neutral trinuclear complex [C₆H₄{NHPPh₂Au(C₆F₅)₃}{N(AuPPh₃)PPh₂Au(C₆F₅)₃}] 20, containing a P,P,N-tridentate ligand. The crystal structures of complexes 1, 3, 4b, 6, 12 and 20 have been established by X-ray diffraction studies.