Michael Lloyd Williams
Jun 1, 2008
Citations
0
Influential Citations
10
Citations
Journal
Inflammopharmacology
Abstract
Gold (atomic symbol Au) is a soft, bright yellow metal with the highest ductility and malleability of any of the elements. Located in group 11 of the periodic table it possesses the electron configuration ds and together with copper and silver, forms the coinage metal group. In its metallic state, gold is one of the most noble of all the metals, being unreactive to oxygen, sulphur, concentrated acids or bases even at elevated temperatures. However, gold reacts readily with halogens and dissolves in solutions containing or generating chlorine such as aqua regia to form H[AuCl4]. Similarly gold dissolves in cyanide solutions in the presence of air or hydrogen peroxide to give the stable dicyano complex [Au(CN)2] . Mild reduction of solutions of the AuCl4 – by various reducing agents such as citric acid may, under suitable conditions, give highly coloured solutions containing colloidal gold. Gold is found naturally in its metallic state (oxidation number 0) and has two common oxidation states namely gold (I) and gold(III). Four less common oxidation states (-I, II, IV and V) have also been reported.(Puddephatt 1980; Schmidbaur 1999) There has been considerable research into the formation of gold coordination compounds by a number of chemical industries. Much of this research was centred on maximising the recovery and purification of gold by the mining industry.(Schmidbaur 1999; Schmid & Curley-Fiarino 1975) More recently, there has been a significant shift in research towards the preparation of biologically active gold(I) and gold(III) species for the treatment of diseases including rheumatoid arthritis and various cancers.(Ho & Tiekink 2005) The gold(I) core has a 5d diamagnetic electronic configuration and exhibits essentially linear, two coordinate geometry in its complexes, independent of the ligand properties. The complexes are primarily associated in neutral coordination e. g. [Ph3PAuCl] or as stable cations e. g. [Au(PPh3)2] + or anions e.g. [Au(CN)2] – in simple ionic complexes. Gold(I) complexes are particularly stable in non-aqueous, aprotic solvents such as acetonitrile. However, they are exceedingly unstable Review