Study on carbon - Hydrogen activation of ketones by Gold(III) complexes and the synthesis and characterization of two ketonylgold(III) complexes

Article abstract of DOI:10.1016/j.jorganchem.2004.06.025

The acetonylgold(III) compound [Au(ppy)(CH₂COCH₃) Cl] (1) (ppy = 2-phenylpyridine) was unexpectedly obtained during the crystallization process of Au(III) lactate complex [Au(ppy) (CH₃CHOHCOO^-)Cl]. This new structure prompted us to further study the role of Au(III) complexes on the carbon-hydrogen activation of ketones. Complex [Au(ppy)(CH₂COCH₃) NO₃] (2) was synthesized by reacting [Au(ppy)(NO₃) ₂] with acetone while the ketonyl Au(III) complex [Au(apd) Cl₂] (3) (Hapd = 2-acetylpyridine) was obtained through carbon-hydrogen bond activation of the acetyl group. The crystal structures of 1 and 2 have common features: a square-planar Au(III) centre coordinated by one five-membered chelate ring, one acetonyl ligand and one anion (chloride or nitrate). Both structures show that carbon-hydrogen activation of acetone by 2-phenylpyridine-Au(III) complexes leads to the formation of acetonyl-Au(III) complexes. The Au-CH 2 bond lengths (2.067(7) ?, 1 and 2.059(5) ?, 2) are similar to each other but longer than the Au-C (phenyl) bond lengths. The two softest ligands (carbanion) are also cis to each other in the thermodynamically most stable isomer. In complex 3, the σ-bonded acetyl group is confirmed by ¹³C DEPT NMR spectroscopy.

Full text of DOI:10.1016/j.jorganchem.2004.06.025

Journal of Organometallic Chemistry 689 (2004) 2969–2974
www.elsevier.com/locate/jorganchem
Study on carbon–hydrogen activation of ketones by
Gold(III) complexes and the synthesis and characterization of two
ketonylgold(III) complexes
a,b,
a
´
, Enrique Melendez , John D. Ranford ,
b
*
Daming Fan
b
b
Peng Foo Lee , Jagadese J. Vittal
a
Department of Chemistry, University of Puerto Rico, Mayagu¨ez, PR 00681, USA
Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
b
Received 15 March 2004; accepted 22 June 2004
Available online 31 July 2004
Abstract
The acetonylgold(III) compound [Au(ppy)(CH2COCH3)Cl] (1) (ppy = 2-phenylpyridine) was unexpectedly obtained during the
crystallization process of Au(III) lactate complex [Au(ppy)(CH3CHOHCOOꢀ)Cl]. This new structure prompted us to further study
the role of Au(III) complexes on the carbon–hydrogen activation of ketones. Complex [Au(ppy)(CH2COCH3)NO3] (2) was synthe-
sized by reacting [Au(ppy)(NO3)2] with acetone while the ketonyl Au(III) complex [Au(apd)Cl2] (3) (Hapd = 2-acetylpyridine) was
obtained through carbon–hydrogen bond activation of the acetyl group. The crystal structures of 1 and 2 have common features: a
square–planar Au(III) centre coordinated by one five-membered chelate ring, one acetonyl ligand and one anion (chloride or ni-
trate). Both structures show that carbon–hydrogen activation of acetone by 2-phenylpyridine–Au(III) complexes leads to the for-
˚
˚
mation of acetonyl–Au(III) complexes. The Au–CH2 bond lengths (2.067(7) A, 1 and 2.059(5) A, 2) are similar to each other
but longer than the Au–C (phenyl) bond lengths. The two softest ligands (carbanion) are also cis to each other in the thermodynam-
ically most stable isomer. In complex 3, the r-bonded acetyl group is confirmed by 13C DEPT NMR spectroscopy.
Ó 2004 Published by Elsevier B.V.
Keywords: Gold(III) complex; C–H activation; X-ray crystallography
1. Introduction
the methyl groups by a cationic (octaethylporphyrinato)
rhodium(III) complex with a non-coordinating perchl-
orate counteranion, (OEP)RhIII(ClO4) [9,10]. They pre-
sented an efficient catalytic cycle in the enolization of
ketone under neutral or mild conditions by the RhIII
complex and in the enolated complex undergoing metal-
lation to give organometalic derivatives or aldol reaction
with free ketone.
Metallated ketones play an important role in organic
synthesis. There are several syntheses in which these
compounds are involved, e.g., direct metallation of ke-
tone by deprotonating agents, oxidative-addition reac-
tions (with a-halogenocarbonyl compounds or
epoxides) or transmetallation reactions [1–9]. In the
work reported by Aoyama in 1987, acetone and methyl
ethyl ketone underwent facile and direct metallation at
´
In 1990, Jose Vicente and coworkers [11–14] reported
that an unusual carbon–hydrogen activation of acetone
occurred by intramolecular cooperation between the
metal center Au(III) and a ligand attached to it. They in-
vestigated the reaction of [Au(pap)Cl2] (pap = 2-phenyl-
azophenyl) in acetone with various reagents such as
*
Corresponding author. Tel.: +6562845922; fax: +6562849277.
E-mail address: dennyfan@hotmail.com (D. Fan).
0022-328X/$ - see front matter Ó 2004 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2004.06.025

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D. Fan et al. / Journal of Organometallic Chemistry 689 (2004) 2969–2974
Tl(acac) (acac = acetylacetonate), KCN, AgClO4, HgR2
(R = C6F5 or pap) or PdR2 (R = C6H4NO2-2) yielding
an acetonyl product [Au(pap)(CH2COMe)Cl]. They also
proposed two plausible reaction pathways for the car-
bon–hydrogen activation of ketones [14]. In Scheme 1
[14], the substitution of the chloro ligands trans to the
nitrogen atom is essential in the proposed pathway.
First, it explains the labilization of the Au–N bond, thus
permitting co-ordination of the acetone molecule, and
then allows intramolecular transfer of the proton to
form the deprotonated acetonyl Au(III) complex. In
Scheme 1(3) for perchlorato-complex [14], the weakly
bonding perchlorate ligand is directly replaced by ace-
tone and the carbon–hydrogen activation is facilitated
through a three-co-ordination of Au(III) intermediate.
The reaction pathways in both schemes have in common
the co-ordination of the ketone and the Au(III) ligand
co-operation in carbon–hydrogen activation. The first
process should be favoured by substitutes on the ketone
with +I or +M effects (electron-releasing substituents,
R = Et, Pr or Bu). It was also suggested that at least
one of the substituents should be a methyl group (+I ef-
fect, low steric requirement).
Ketonylgold(III) complexes may play an important
role in organic synthesis. As observed in other organo-
transition–metal complexes [15–18], Au(III) complexes
could serve as efficient deprotonating agents to generate
enolization reagents or as metallo-enzyme catalyst in the
biological enolization. The carbon–hydrogen activation
of ketones by Au(III) complexes provides more options
in the substitution at the a-position of the carbonyl
group, such as in the halogenation and aldol reactions
with C–C bond formation. There are a few syntheses
and structures of ketonyl Au(III) complexes reported
to date but their potential applications in organic reac-
tion has not been explored extensively [11–14,19].
As part of our studies into the chemical and biologi-
cal properties of Au(III) complexes, we recently reported
synthesis of two series of Au(III) complexes with
r-bond C,N 2-phenylpyridine and N,N pyrazole or
picolinamide ligands through direct deprotonation
[20–23]. The strong polarizing property of Au(III) leads
to direct metallation of Au(III) with 2-phenylpyridine
under reflux and with pyrazole or picolinamide under
mild conditions. During our study on 2-phenylpyridine
Au(III) complexes, the crystallization of a Au(III) lac-
tate complex [Au(ppy)(CH3CHOHCOOꢀ)Cl] in acetone
gave an acetonyl Au(III) compound [Au(ppy)(CH2-
COCH3)Cl], instead of the expected product. This indi-
cates that Au(III) complexes are important agents for
the carbon–hydrogen activation of ketones. The unex-
pected carbon–hydrogen activation of acetone by
Au(III) complexes motivated us to extend our research
into the synthesis of new Au(III) complexes containing
a Au–C r-bonded ketonyl group. Thus, the intermedi-
ate [Au(ppy)(NO3)2] was reacted with solvent acetone
for 3 days giving the acetonylgold(III) complex 2. 2-Ace-
tylpyridine (Hapd) reacted with Na[AuCl4] Æ 2H2O to
give the neutral molecular ketonylgold(III) complex
[Au(apd)Cl2] (3). Herein, we report the structural
features of two new acetonylgold(III) and one ketonyl-
gold(III) complexes.
2. Results and discussion
In an attempt to synthesize a 2-phenylpyridine
Au(III) lactate complex, [Au(ppy)Cl2] was reacted with
silver lactate for 10 h forming apparently a labile inter-
mediate species, ‘‘[Au(ppy)(CH3CHOHCOOꢀ)Cl]’’,
which in presence of acetone undergoes C–H activation
yielding the [Au(ppy)(CH2COCH3)Cl] (1),
½AuðppyÞCl2ꢁ þ AgðC3H5O3Þ
! \½AuðppyÞðCH3CHOHCOOꢀÞClꢁ" þ acetone
! 1
ð1Þ
In fact, the crystals of 1 were grown during the proc-
ess of crystallization of a 2-phenylpyridine Au(III) lac-
tate complex in acetone. After two days, it was the
compound [Au(ppy)(CH2COCH3)Cl] formed instead
of the expected product. Complex 2 was prepared by
treating intermediate [Au(ppy)(NO3)2] with acetone for
72 h at room temperature to complete the activation
process.
In an attempt to extend the applicability of Au(III)
species in the carbon–hydrogen activation of ketone,
we explored the 2-acetylpyridine as a suitable ligand in
the preparation of r-bonded C–Au(III) complex
through direct deprotonation of the methyl group. The
reaction between 2-acetylpyridine and Na[AuCl4] Æ 2-
H2O in water was completed under mild conditions for
3 days to afford the ketonyl complex [Au(apd)Cl2] (3),
in a good yield,
Na½AuCl4ꢁ ꢂ 2H2O þ 2-acetylpyridine ! ½AuðapdÞCl2ꢁ
ð2Þ
3. Crystal structures
The structures of 1 and 2 were confirmed by X-ray
crystallography. Figs. 1 and 2 depict the molecular
structures 1 and 2, respectively. Selected bond distances
and angles are given in Table 2.
The two ketonyl Au(III) structures reveal neutral
molecules with a square–planar geometry around the
gold centre with both structures having common fea-
tures. The chelate ring of the ppy ligand is associated
with some distortion at the narrow C–Au–N bond angle
(81.1(2)° in 1 and 81.8(2)° in 2), and a concomitant

D. Fan et al. / Journal of Organometallic Chemistry 689 (2004) 2969–2974
2971
Table 1
Crystallographic data and structure refinement details for 1 and 2
Complex
1
2
Formula
Formula weight
Temperature (K)
C14H13AuClNO
443.67
293(2)
C14H13AuN2O4
470.23
293(2)
˚
Wavelength, k (A)
Crystal system
0.71073
Triclinic
P21/c
0.71073
Monoclinic
ꢀ
Space group
˚
P1
a (A)
˚
7.7676(3)
9.3952(3)
9.5779(3)
90.193(1)
101.101(1)
100.850(1)
673.07(4)
2
8.9969(3)
20.2059(6)
8.1420(3)
65.668(1)
106.632(1)
64.721(1)
1418.21(8)
4
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
V (A )
Z
Dcalc (g cmꢀ3
)
2.189
11.113
2.202
10.390
l (mmꢀ1
)
Reflections collected
Independent reflections
Rint
4368
3115
8763
3507
0.0203
1.053
0.0376
0.999
Goodness-of-fit
Final R[I > 2r]
R1
Fig. 2. An ORTEP view of 2 showing the numbering scheme.
a
0.0365
0.0954
0.0304
0.0611
b
wR2
Table 2
Selected bond lengths (A) and angles (°) for 1 and 2
P
P
a
˚
R1 = iFoj ꢀ jFci/ jFoj.
P
P
2
2 1=2
b
wR2 ¼ ½ wðF 2o ꢀ F c2Þ = wðF 2oÞ ꢁ
.
1
2
Au(1)–C(1)
Au(1)–N(1)
Au(1)–Cl(1)
Au(1)–C(12)
C(12)–C(13)
O(1)–C(13)
C(13)–C(14)
N(1)–C(7)
2.018(7)
2.110(5)
2.370(2)
2.059(5)
1.492(11)
1.227(9)
1.496(13)
1.355(9)
1.346(9)
Au(1)–C(1)
Au(1)–N(1)
Au(1)–O(1)
Au(1)–C(12)
C(12)–C(13)
O(4)–C(13)
O(1)–N(2)
O(2)–N(2)
O(3)–N(2)
2.003(4)
2.114(4)
2.128(3)
2.059(5)
1.472(7)
1.209(6)
1.323(6)
1.221(6)
1.219(5)
N(1)–C(11)
C(1)–Au(1)–N(1)
C(1)–Au(1)–C(12)
N(1)–Au(1)–C(12)
C(1)–Au(1)–Cl(1)
N(1)–Au(1)–Cl(1)
C(12)–Au(1)–Cl(1)
81.1(2)
94.6(3)
175.4(2)
C(1)–Au(1)–N(1)
C(1)–Au(1)–C(12)
N(1)–Au(1)–C(12)
81.8(2)
93.1(3)
177.7(2)
174.6(2)
92.96(14)
89.2(2)
174.59(18) C(1)–Au(1)–O(1)
94.72(17)
89.7(2)
N(1)–Au(1)–O(1)
C(12)–Au(1)–O(1)
C(13)–C(12)–Au(1) 108.3(5)
C(13)–C(12)–Au(1) 112.1(3)
C(2)–C(1)–Au(1)
C(6)–C(1)–Au(1)
C(7)–N(1)–Au(1)
127.9(5)
112.6(5)
114.0(4)
N(2)–O(1)–Au(1)
O(2)–N(2)–O(1)
O(2)–N(2)–O(3)
112.7(3)
118.6(5)
125.1(5)
other in spite of the different trans ligands. Similar Au–C
(aryl) bond lengths are observed trans to an oxygen do-
Fig. 1. An ORTEP view of 1 showing the numbering scheme.
˚
nor, as in [Au(ppy)(ace)2] (2.005(8) A), [Au(ppy)(bz)2]
ꢀ
2
˚
(bz = C6H5COO , 2.001(9) A), and [Au(g -C6H4CH2-
2
˚
opening of N(1)–Au–Cl(1) (94.72(17)°) and C(1)–Au–
C(12) (96.6(3)°) for 1 and of C(1)–Au–C(12) (96.0(2)°)
and N(1)–Au–O(1) (92.96(14)°) in 2. This structural fea-
ture is also observed in other 2-phenylpyridine Au(III)
complexes, such as [Au(ppy)Cl2] and [Au(ppy)(ace)2]
(ace = acetate) [21]. The two Au–C (phenyl) bond dis-
NMe2-2)(g -quin)] (quin = quinolin-8-olate, 2.021(7) A)
[19,21]. The two gold-ketonyl bonds in both complexes
˚
˚
(2.067(7) A, 1 and 2.059(5) A, 2) are also similar to each
other. However, the Au–CH2 (sp3 hybridization at car-
bon) bond lengths are longer than the Au–C (phenyl,
sp2 at carbon)) bonds in these two complexes, probably
because of the different hybridization of the carbon
˚
˚
tances are similar (2.018(7) A 1 and 2.003(4) A 2) to each

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D. Fan et al. / Journal of Organometallic Chemistry 689 (2004) 2969–2974
Table 4
1H and 13C DEPT(45) NMR Data for complex 3 (d, DMSO-d6
solutions)
atoms. In 2, the nitrato N(2)–O(1) bond distance
˚
(1.323(6) A) is longer than the other two N(2)–O(2)
˚
˚
(1.221(6) A) and N(2)–O(3) (1.219(5) A) bonds as the
O(1) atom is directly bound to gold.
Pyridine ring
–COCH2
1H
13C
9.62(d), 8.55(t), 8.17(t), 8.08(d)
147.8, 144.1, 131.3, 126.0
3.72(s)
57.7
Compared with other ketonyl Au(III) crystal struc-
tures of [Au{C6H3(N‚NC6H4Me-40)-2-Me-5}(acac-
˚
C)Cl] (acac = acetylacetonate, Au–C(1) 2.083(4) A)
[13] and [Au(mpap)(CH2COMe)(py)]ClO4 (mpap =
C6H3(N‚NC6H4Me-4)-2-Me-5, py = pyridine, Au–
for a methylene group and four peaks at d 9.62(d),
8.55(t), 8.17(t), 8.08(d) for the pyridine ring protons.
The integration ratio of H on the pyridine ring to on
the acetyl group is 4:2. Compared with the 1H spectrum
of the ligand 2-acetylpyridine in DMSO-d6 (d 8.69 (1H,
d), 7.93(2H, m), 7.62(1H, t), 2.60(3H, d)), there is a sig-
nificant downfield shift of proton resonance after form-
ing the Au(III) complex. Other ketonyl Au(III)
˚
C(1) 2.061(6) A) [14], the Au–CH2 bond length of
˚
˚
2.059(5) A for 2 and 2.067(7) A for 1 are similar. The
angle of Au–CH2–CO in 2 is 108.3(5)°, which is close
to 109.1(2)° of [Au{C6H3(N‚NC6H4Me-40)-2-Me-5}-
(acac-C)Cl] but smaller than 112.1(3)° for 1 and
114.5(4)° of [Au(mpap)(CH2COMe)(py)]ClO4. Like
other Au(III) complexes, these ketonyl complexes have
the expected structures, with square–planar coordination
at the gold atom. As a result of the trans influence, it was
also expected that the two softest ligands (carboanion)
would be cis to each other in the thermodynamically
most stable isomer, as we observed in our structures.
1
complexes also show the methylene H resonance as a
singlet in the range d 3.3–3.5 [14]. The chemical shift
change of acetyl group indicates the deprotonation of
the methyl group in the reaction and consequently the
formation of the Au–CH2 bond. The formation of a
Au–CH2 bond was also confirmed by a 13C DEPT(135)
spectrum, in which a negative peak for CH2 is present at
d 57.7, whereas four positive peaks at d 147.8, 144.1,
131.3 and 126.0 belong to the four CH groups on the py-
ridine ring.
The detail mechanism of the carbon–hydrogen acti-
vation of ketones by Au(III) complexes is unclear to
date. The proposed reaction pathway in Scheme 1(3)
for the perchlorato-complex by Vicente [14] seems to
be applicable to the formation of 2, in which the enoli-
zation in the carbon–hydrogen activation process is fa-
cilitated by the three-co-ordination of Au(III)
intermediates. Three-co-ordination of Au(III) interme-
diates have been established previously [27–29]. It is rea-
sonable to postulate that the weakly bonding nitrate
ligand is replaced by the acetone, instead of labilizing
the ligand trans to it to allow the co-ordination of ace-
tone cis to the nitrogen atom, as the proposed reaction
pathway in Scheme 1 for other Au(III) complexes [14].
However, both schemes are unfit to the formation of 3
because there is neither the substitution of chloride lig-
and trans to the nitrogen atom as described in Scheme
1 nor the weakly bonding ligand replacement by acetone
in Scheme 1(3). It is unlikely that methyl group could
co-operate with the intramolecular base pyridine due
to steric restraint. In this paper, we postulate a plausible
4. Spectroscopic studies
The infrared spectra of 2 and 3 are consistent with the
presence of a coordinated ketonyl group. A strong ab-
sorption band at ca. 1685 cmꢀ1 corresponding to
m(CO) is shown in both complexes. The IR spectrum
of 2 has strong ppy ligand modes at ca. 1492, 1450,
786, 768, and 732 cmꢀ1, which are observed in other
2-phenylpyridine complexes [21–26]. The strong bands
around 1600–1575 cmꢀ1 correspond to the pyridine lig-
and in 3.
1
The H and 13C DEPT(135) NMR chemical shifts of
2 and 3 are listed in Tables 3 and 4, respectively. The 1H
spectrum of the 2-phenylpyridine in 2 is similar to that
in other 2-phenylpyridine Au(III) complexes [21,22],
while two singlet peaks at d 3.66 and 2.42 correspond
to –CH2– and –CH3 groups, respectively. The 13C
DEPT(135) spectrum of 2 gave a negative peak at d
56.8 showing the presence of a –CH2– group and 9 pos-
itive peaks corresponding to 8 –CH– groups on the 2-
phenylpyridine and one methyl group. It shows that
the formation of Au–CH2 bond leads to the methylene
resonance at low filed compared with the methyl group.
The proton spectrum of 3 shows a single peak at d 3.72
Table 3
1H and 13C DEPT(45) NMR Data for complex 2 (d, DMSO-d6 solutions)a
1H
H11
H9
H8
H5
H2
H10
H4
H3
H12
H14
8.75
8.44
7.94
7.78
7.52
7.40
7.33
7.26
3.66
2.42
13C
2-Phenylpyridine
121.8 125.2
–CH2COCH3
33.5 56.8
126.3
128.3
129.1
131.5
146.5
152.8
a
See Fig. 2 for 1H numbering scheme.

D. Fan et al. / Journal of Organometallic Chemistry 689 (2004) 2969–2974
2973
(b)
Cl
(c)
Cl
Au
O
Au
O
N
Cl
N
Cl
(A)
Cl
Au
Cl
C
Cl
CH2
C
N
C
Cl
CH2
H
N
O
C
O
HN
O
C
C
H3
H3C
CH3
(d)
Cl
Cl
Cl
Au
N
H
Au
N
Cl
O
H
C
C
C
CH2
H2
(3)
O
C
O
N
H
3C
Scheme 1. Proposed reaction pathway for the synthesis of complex 3.
reaction pathway for the carbon–hydrogen activation of
the acetyl group by Au(III) complex (See Scheme 1).
First, it was the pyridine bound to Au forming A and
secondly the oxygen atom on carbonyl group replaced
the neighbouring chloride giving a five-membered
chelating ring (B). With the aid of free trace 2-acetylpy-
ridine in the solution, the highly electrophilic nature of
the central ion Au(III) leads to the cooperation between
the Au(III) center and the acetyl group to allow transfer
of the proton shown in C or D, giving the deprotonated
product 3. The intramolecular co-operation between
metal and internal ligands in C–H activation of ketones
has been reported in a few cases [9,10,13,14]. However,
the formation of 3 in this work is possibly through the
intermolecular cooperation between 2-acetylpyridine
and Au(III). Further studies on carbon–hydrogen acti-
vation of ketones will be devoted in order to fully under-
stand the mechanism of formation of ketonyl Au(III)
complexes as well as its potential application in the di-
rect metallation of ketones and aldol reactions.
to solvent. The Infrared spectra (KBr pellet) were re-
corded using an FTS165 Bio-Rad FTIR spectropho-
tometer in the range 4000–450 cmꢀ1
. Elemental
analyses were performed in the Microanalytical Labo-
ratory, Department of Chemistry, National University
of Singapore.
Complex [Au(ppy)Cl2] was synthesized according to
literature methods [24].
5.1. [Au(ppy)(CH2COCH3)Cl] (1)
Single crystals of 1 were obtained during the crystal-
lization of a 2-phenylpyridine Au(III) lactate complex
[Au(ppy)(CH3CHOHCOOꢀ)Cl]. In an attempt to syn-
thesize a 2-phenylpyridine Au(III) lactate complex,
[Au(ppy)Cl2] was reacted with silver lactate in the dark
for 10 h. The mixture was filtered and the filtrate was ro-
tatoevaporated to a small volume to crystallize by va-
pour diffusion of diethyl ether into acetone in an ice
bath. White crystals of 1 grew after 3 days.
5. Experimental
5.2. [Au(ppy)(CH2COCH3)NO3] (2)
Na[AuCl4] Æ 2H2O and 2-phenylpyridine were ob-
tained from Aldrich Chemical Co. Milwankee, Wiscon-
sin, USA. All other reagents were purchased from Fluka
Chemie AG, Buchs, Switzerland.
NMR spectra were recorded on a Bruker ACF 300
(1H, 13C) spectrometer at 25 °C and were referenced
[Au(ppy)Cl2] (0.52 g, 1.2 mmol) was dissolved in ace-
tone (30 ml) and silver nitrate (0.42 g, 2.4 mmol) added.
The mixture was stirred in the dark for 2 h and the silver
chloride filtered off. The colourless filtrate was stirred in
the dark for 3 days and then it was rotatoevaporated
to a small volume. The concentrated solution was

2974
D. Fan et al. / Journal of Organometallic Chemistry 689 (2004) 2969–2974
crystallized by vapour diffusion of diethyl ether into it.
White crystals of 2 were grown in a freezer. Yield:
0.12 g (21%). Anal. for C14H13AuN2O4 (Calc. in paren-
thesis): C, 35.86 (35.74); H, 2.73 (2.77); N, 5.88 (5.96);
Au, 41.85 (41.91). IR (KBr, cmꢀ1): m(CO) 1685,
m(C–N)ppy 1492, 1450, 786, 768, 732.
References
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5.3. [Au(apd)Cl2] (3)
Na[AuCl4] Æ 2H2O (0.81 g, 2.0 mmol) was dissolved in
water (20 ml) in a round bottom Schlenk flask. 2-Acetyl-
pyridine (0.23 ml, 2.1 mmol) in water (10 ml) was then
added dropwise with stirring and a yellow suspension
formed. The mixture was stirred in the dark under nitro-
gen at 60 °C for 3 days. It was then filtered and washed
with water; the residue was dried in vacuo, extracted
with dichloromethane and filtered off. The solution
was concentrated (3 ml), whereupon addition of diethyl
ether (5 ml) and crystallization from dichloromethane/
diethyl ether gave the corresponding complex 3. Yield:
0.44 g (56%). Anal. for C7H6AuNOCl2 (Calc. in paren-
theses): C, 21.45 (21.65); H, 1.60 (1.55); N, 3.71 (3.61);
Au, 50.45 (50.77). IR (KBr, cmꢀ1): m(CO) 1685, m(C–
N)py 1600–1575.
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6. X-ray crystallography
The diffraction experiments were carried out on a
Bruker AXS SMART CCD diffractometer. The program
SMART [30] was used for collecting the intensity data,
for reflections indexing and for the determination of lat-
tice parameters, SAINT [30] was used for integration of
the intensity of reflections and scaling, SADABS [31] was
used for absorption correction and SHELXTL [32] for
space group and structure determination, least-squares
refinements on F2. All non-H atoms were refined with an-
isotropic thermal parameters. Selected crystallographic
data and refinement details are displayed in Table 1.
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Acknowledgement
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(1974) 6140.
We are grateful for Grant 970614 from the National
University of Singapore.
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[30] SMART
& SAINT Software Reference manuals, Version 6.22,
Appendix A. Supplementary material
Bruker AXS Analytic X-Ray Systems, Inc., Madison, WI, 2000.
[31] G.M. Sheldrick, SADABS. Software for Empirical Absorption
Correction, University of Go¨ttingen, Germany, 2000.
Supplementary data associated with this article can
be found, in the online version, at doi:10.1016/j.jorgan-
chem.2004.06.025.
[32] HELXTL Reverence Manual, Version 5.1, Bruker AXS, Analytic
X-Ray Systems, Inc., Madison, WI, 1997.