Gold(III) diazonium complexes for electrochemical reductive grafting.

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.