Competition of thiols and cyanide for gold(I)

Abstract

Thiol ligands are capable of partially displacing cyanide from Au(CN),-, demonstrating that their affinity for gold(1) is very high. Raman and 13C N M R evidence for the formation in solution of mixed-ligand complexes, RSAuCN-, which disproportionate to Au(CN),-and (RS),Au-, is presented. With use of literature values for reduction potentials, the conditional equilibrium formation constants at pH 7.0 of (cysteinato)gold(I), K = 1.5 X and bis(cysteinato)gold(I), K = 3 X IO2*, were calculated for comparison to the formation constants of Au(CN),-. A potential gold metabolite, bis(glutathionato)goId(I), was generated in situ, characterized by "C N M R , and studied in reactions with cyanide.

Isomeric Mono‐ and Bis[(phosphane)gold(I)] Thiocyanate Complexes

“…[28] In solution, the heteroleptic form (R 3 P)AuSCN may be the component of an equilibrium including the two homoleptic ionic species as demonstrated, for example, for cyano gold(i) complexes [29,[36][37][38] or anions X À other than thiocyanate. [1,28,[39][40][41][42] The ionic form may also appear in the solid state [Eq.…”

Is local biotransformation the key to understanding the pharmacological activity of salicylates and gold drugs?

“…Hydrogen cyanide and cyanogen chloride are identified products from PMN or isolated myeloperoxidase [2]. There is considerable chemical evidence that cyanide displaces thiol ligands from the gold in polymeric gold complexes [3,4]. By analogy, cyanide would be expected to displace gold from its binding site on albumin, thus generating aurocyanide as shown in Fig.…”

“…attenuated activity, in which case the parent drug acts merely as a scavenging agent to "mop up" one or more of the free radicals, or related reactive products, generated by the inflammatory cells or b. enhanced activity, behaving as a new drug species formed in situ. 4. Such a new drug, particularly if it is hydrophilic and formed intracellulary, may be more pharmacologically active than the same molecular species applied systematically or to isolated cells.…”

13C-n.m.r. studies of the binding of 1,3-diazinane-2-selenone and 1,3-diazipine-2-selenone to gold(I) drugs

“…The exchange reactions of gold(I) drugs with thiols, CN ) and selenols have been reported [1][2][3][4][5][6][7][8]. These ligands, when added to e.g.…”