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Cycloaurated gold(III) complexes derived from the functionalised catecholate ligands alizarin and 3,4-dihydroxybenzaldehyde

Research paper by Tiffany S. Smith, Joseph R. Lane, Michael R. Mucalo, William Henderson

Indexed on: 12 May '16Published on: 11 May '16Published in: Transition Metal Chemistry



Abstract

Reactions of the cycloaurated gold(III) dichloride complexes [AuCl2(anp)] (anp = 2-anilinopyridyl), [AuCl2(bp)] (bp = 2-benzylpyridyl) and [AuCl2(tolpy)] (tolpy = 2-(p-tolyl)pyridyl) with alizarin (H2az) and Me3N base in refluxing methanol gave the complexes [Au(az)L] (L = anp, bp or tolpy). Additionally, the reaction of [AuCl2(tolpy)] with 3,4-dihydroxybenzaldehyde (H2dhb) and Me3N gave the complex [Au(dhb)(tolpy)]. These complexes contain the ligands coordinated as functionalised catecholate groups, allowing introduction of new functionalities into this class of complex. The complexes are poorly soluble in most organic solvents but were successfully characterised by ESI MS, IR and NMR spectroscopies. A detailed 1H and 13C NMR study on [Au(dhb)(tolpy)] shows that it exists as two isomers with regard to the position of the aldehyde group compared to the cycloaurated ring system; DFT calculations were carried out in order to provide some insight on the spectroscopic assignment of the two isomers.