Abstract
D.Sc.
This study involves the preparation and characterization of new amino(thio) carbene complexes
of gold(I) and gold(III). In addition the reactivity of bis(thiazolyl) aurate and the above
mentioned carbene complexes are also described.
Various thiazolyllithium reagents reacted with [AuCl(tht)] to yield bis(thiazolyl) aurate complexes
of gold(I) which were isolated in crystalline form. These crystals contained solvent of
crystallization and no structural determination of these aurates were possible. The latter
compounds readily reacted with elemental sulphur by insertion of a sulphur atom into one of the
Au-C bonds thereof Subsequent reaction with one molar equivalent of CF 3S03CH3 or CF3SO3H
produced either carbene, [Au(CNRYS)(SC=NY§)] (Y = CCH 3=CH, C4H6; R = H,
CH3), or thione, [Au(S=h‘TRY)(C=NYS)], complexes of gold(I) which spontaneously
decomposed into gold(I) polymers ([Au(C=NYS)]. or [Au(S&=NY)].) and organic products
(C=NYS or S=CNRYS). In an attempt to isolate the above-mentioned carbene or thione
complexes bis(thiazolyl) aurate complexes were treated with two molar equivalents of
CF3S03CH3 or CF3SO3H after sulphur insertion. Rather than the expected mixed carbene thione
complexes, [Au(elsTRY§)(S=eNRY§)]CF 3S03, homoleptic rearrangement produced bis(carbene)
complexes of gold(I) with unexpected counterions (Cl instead of CF 3SO3).
Reaction of lithiated mercaptobenzothiazole with [AuCl(tht)] yielded a bis(thiolate) complex of
gold(I), [Au(SC=NC 6H4 S-0)2]Li. Alkylation or protonation of this modified aurate complex
resulted in the formation of gold polymers, [Au(S=NC 6H4 -0)]„, and organic products,
S=§NRC6H4§-o, R=H, CH3 ).
Oxidative addition of halogens to bis(thiazolyl) aurate complexes produced no isolable
organometallic complexes. [AuC1 1]Li probably formed after repetitive oxidation addition (C1 2)
and reductive elimination reaction (2-chlorothiazole). However, oxidation of these aurate
complexes with SOC12 limited the reaction to one oxidative addition and one reductive elimination
step to produce [AuCl(CNHYS)] (Y=CCH 3=CH, C6H4) after acidification.
Reaction of the neutral mono(carbene) complex [Au(CNCCH 3=CHS)(C=NCCH3=CHS)] with
C12, Br2 or 12 produced carbene complexes of gold(I), [AuX(6NHCCH 3=CH§)] (X=C1, Br, I),
after reductive elimination of 2-halogeno-4-methylthiazole.
Cationic bis(thiazolinylidene) complexes of gold(I) react readily with C1 2 and 12 to produce stable
Ms(carbene) complexes of gold(III). However, oxidative addition on the same carbene complex
by I2 is followed by a novel reductive elimination of (ICNii)cF SO to produce carbene
complexes of gold(I), [AuI(CMN7- TTA )].
Alkylation (CF3SO3CH3) of 4-methylthiazole, bensothiazole and methylimidazole, followed by
deprotonation (BuLi) produced free carbenes. These carbenes were trapped by reaction with
[AuCl(tht)] to form carbene-chloro complexes of gold(I). Chloro(1,3-
dimethylimidazolinylidene)gold(I) react readily with NaN 3 or AgNO3 to yield
[AuX(CNCH3CH=CH1:TCH3)] (X = N3 or NO3 ).
As part of this study the structures of several carbene complexes were determined, including five
carbene complexes of gold(I) and one carbene complex of gold(III). Au-C bond lengths of
between 1.92-2.13A were found with the largest Au-C separation in the carbene complex of
gold(III), [Au(aNCH3CH=CHNCH3)2]CF3S03 . Certain complexes of gold(I) exhibit interesting
Au...Au interactions (3.19-3.51A) resulting in the aggregation of gold atoms to form dimers and
chains of gold(I) atoms.
The structures of two related complexes of iron were also determined to investigate the effect of
protonation on a neutral carbene precursor, [Fe(CO) 2Cp(C=CHCH=NNPh)], to form the cationic
carbene complex, [Fe(C0) 2Cp(aCH=CHNHI:IPh)JCF3S03. Small changes in bond lengths and
angles resulted upon carbene formation.