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.