Gold(III) diazonium complexes were synthesized for the first time and studied for electrochemical reductive grafting. The diazonium complex [CN-4-C(6)H(4)N≡N]AuCl(4) was synthesized by protonating CN-4-C(6)H(4)NH(2) with chloroauric acid H[AuCl(4)]·3H(2)O to form the ammonium salt [CN-4-C(6)H(4)NH(3)]AuCl(4), which was then oxidized by the one-electron oxidizing agent [NO]PF(6) in CH(3)CN. The highly irreversible reduction potential of 0.1 mM [CN-4-C(6)H(4)N≡N]AuCl(4) observed at -0.06 V versus Ag/AgCl in CH(3)CN/0.1 M [Bu(4)N]PF(6) encompasses both gold(0) deposition and diazonium reduction. Repeated scans showed the absence of the reduction peak on the second run, which indicates that surface modification with a blocking gold aryl film has occurred and is largely complete.

Abstract:The synthesis of diazonium tetrachloroaurate(III) complexes [R-4-C 6 H 4 N≡N]AuCl 4 involves protonation of anilines

The one-electron oxidizing agent [NO]PF 6 was reacted with Bu 4 N[Au(C 6 X 5 ) 2 ] (X = F, Cl) complexes in CH 3 CN. The gold(III) complexes [Au(C 6 F 5 ) 3 (CH 3 CN)] and cis-[Au(C 6 Cl 5 ) 2 (CH 3 CN) 2 ]PF 6 were synthesized by the oxidation of gold(I) to gold(III) with the concomitant ligand rearrangement "oxidative rearrangement". The supramolecular crystal packing in the perfluorinated aryl gold(III) complex is dictated by the notably short C(sp 2 )−F···H(CH 3 CN) bond distance. The [Au(C 6 Cl 5 ) 2 (CH 3 CN) 2 ]PF 6 complex exhibits antisymbiosis, displaying equal ligands in the cis position. The electrochemical oxidation of Bu 4 N[Au(C 6 X 5 ) 2 ] (X = F, Cl) complexes in CH 3 CN showed two irreversible peaks at 0.71 and 1.21 V (X = F) and at 0.65 and 0.91 V (X = Cl) vs Ag/AgCl.