Gold complexes thiazole

NMR experiments where undertaken to determine the site of coordination of the two other complexes. The thioether complex showed an upheld shift for the N-atom in the thioether gold complex and a similar result was obtained in the case of the thiazole compound, confirming imine coordination. 

Cronje, S., Raubenheimer, H.G., Spies, H.S.C., Esterhuysen, C., Schmidbaur, H., Schier, A. and Kruger, G.J. (2003) Synthesis and characterisation of N-coordinated pentafluorophenyl gold(I) thiazole-derived complexes and an unusual self-assembly to form a tetrameric gold(I) complex. Dalton Transactions, (14), 2859-2866. 

NCS-carbon is shifted dowfield in the two first complexes. The amine complex shows a shift of the N—H signal which appears at 2.08 ppm in the free ligand and at 5.17 ppm when it is coordinated. The structure of the thiazole complex was studied by X-ray diffraction, confirming the almost linear coordination about the gold atom and showing that the ligands are almost co-planar. 

Two major routes give access to (thiazol-2-ylidene)gold(i) complexes with 1 1 stoichiometry. The corresponding thiazolium salts react with base in the presence of gold(i) precursors to give the products in high yield. Alternatively, the corresponding carbeniate complexes can be A-protonated or A-alkylated to afford compounds of this series (Scheme 65).257,266... 

Lithiated thiazols react with (Ph3P)AuGl to a neutral gold thiazolate, which upon alkylation is transformed into the cationic carbene complex, while the reaction with (tht)AuC6Fs followed by alkylation leads to the neutral complex (Scheme 65).260... 

One Au-C bond in bis(thiazol-2-ylidene)gold cations is cleaved in the reaction with elemental iodine to give the corresponding (carbene)AuI complex and a 2-iodo-thiazolium salt, while chlorine and bromine oxidize the gold center to the gold(m) state.267... 

Whereas copper(I) thiazol-2-ylidene complexes are monocarbene and linear complexes that can form weak dimers in the solid state, the analogons gold(I) complexes could be synthesised as linear mono- or bis-carbene complexes. Since the metal requires a monoanionic ligand to balance its one positive charge, monocarbene complexes are normally neutral whereas the corresponding bis-carbene complexes are ionic. Partial protonation... 

Using the same synthetic route, Raubenheimer et al. could also prepare the analogous iso-thiazol-5-ylidene complexes of gold(l) [53] (see Figure 6.16). 

Raman spectroscopy has been used in the spectral analysis of several benzothiazolines <77HCA215> and some benzothiazolium photochromic styryl dyes <93SA(A)1055>. Gold (III) chloride complexes of the type of LAuCh (L = thiazole) have been studied by low frequency Raman and infrared spectroscopy <93Mi 306-03>. 

Gold(III) complexes are quite labile. Tobe reports a stopped flow study of the kinetics of substitution reactions of MeOH in [Au(C6H5)(MeOH)Cl2] at temperatures up to 0 °C in methanol. For anionic reagents, Nu , complexation is via a solvento pathway. The trans effect order of Nu and Nu parallels that for reactions of [AuC ]", although the nucleophilic discrimination is lower than in other gold(III) complexes. The kinetics of replacement of a range of thiazoles, oxazoles, and substituted pyridines, L, from the square-planar complexes [AUCI3L] by Cl in... 

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