(β-Diketiminato)dimethylgold(III): Synthesis, Structure, and Reactivity

Article abstract of DOI:10.1021/om100038f

The reaction between [Me₂AuCl]₂ and the lithium salt of a β-diketimine, [HC{C(Me)N(C₆H₃-2,6-Me ₂)}₂Li], yields the neutral Au(III) compound [HC{C(Me)N(C₆H₃-2,6-Me₂)}₂AuMe ₂] (1). Compound 1 reacts with 1 equiv of triflic acid (HOTf) at -78 °C to provide the cationic Au(III) compound [H₂C{C(Me)N(C ₆H₃-2,6-Me₂)}₂AuMe₂][OTf] (2). Treatment of 1 with 2 equiv of HOTf results in the displacement of Me ₂AuOTf and formation of the β-diketiminato triflate salt [HC{C(Me)NH(C₆H₃-2,6-Me₂)}₂][OTf] (3). Compound 1 reacts with I₂ to yield the cation [HC(I){C(Me)N(C₆H₃-2,6-Me₂)} ₂AuMe₂]⁺, which is isolated as the triflate salt [HC(I){C(Me)N(C₆H₃-2,6-Me₂)} ₂AuMe₂][OTf] (4). The reaction of 1 with (PPh ₃)AuCl in the presence of AgOTf provides [HC(AuPPh ₃){C(Me)N(C₆H₃-2,6-Me₂)} ₂AuMe₂][OTf] (5). Molecular structures of 1, 4, and 5 were elucidated by single-crystal X-ray diffraction experiments; that of 4 was additionally confirmed by quantum-chemical calculations. The reactivity experiments indicate that the methine carbon in the β-diketiminato unit of 1 is the exclusive site of electrophilic attack, while the Au-C bonds are not perturbed.

Full text of DOI:10.1021/om100038f

2248 Organometallics 2010, 29, 2248–2253
DOI: 10.1021/om100038f
(β-Diketiminato)dimethylgold(III): Synthesis, Structure, and Reactivity
†
Ajay Venugopal, Manik Kumer Ghosh, Hannes Jurgens, Karl W. Tornroos,
†
‡
§
€
€
Ole Swang,† Mats Tilset,‡ and Richard H. Heyn*,†
†SINTEF Materials and Chemistry, P.O. Box 124, Blindern, 0314 Oslo, Norway, ‡Department of Chemistry,
University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo, Norway, and §Department of Chemistry, University
ꢀ
of Bergen, Allegaten 41, 5007 Bergen, Norway
Received January 15, 2010
The reaction between [Me2AuCl]2 and the lithium salt of a β-diketimine, [HC{C(Me)N(C6H3-2,
6-Me2)}2Li], yields the neutral Au(III) compound [HC{C(Me)N(C6H3-2,6-Me2)}2AuMe2] (1).
Compound 1 reacts with 1 equiv of triflic acid (HOTf) at -78 °C to provide the cationic
Au(III) compound [H2C{C(Me)N(C6H3-2,6-Me2)}2AuMe2][OTf] (2). Treatment of 1 with 2 equiv
of HOTf results in the displacement of Me2AuOTf and formation of the β-diketiminato triflate salt
[HC{C(Me)NH(C6H3-2,6-Me2)}2][OTf] (3). Compound 1 reacts with I2 to yield the cation [HC(I)-
{C(Me)N(C6H3-2,6-Me2)}2AuMe2]þ, which is isolated as the triflate salt [HC(I){C(Me)N(C6H3-2,6-
Me2)}2AuMe2][OTf] (4). The reaction of 1 with (PPh3)AuCl in the presence of AgOTf provides
[HC(AuPPh3){C(Me)N(C6H3-2,6-Me2)}2AuMe2][OTf] (5). Molecular structures of 1, 4, and 5 were
elucidated by single-crystal X-ray diffraction experiments; that of 4 was additionally confirmed by
quantum-chemical calculations. The reactivity experiments indicate that the methine carbon in the
β-diketiminato unit of 1 is the exclusive site of electrophilic attack, while the Au-C bonds are not
perturbed.
Introduction
and an analogous system based on Au.6 Other Au complexes
are reported to catalyze alkane oxygenation with hydrogen
peroxide.7 Theoretical investigations point out that C-H
bond activation in alkanes can be catalyzed by gold com-
plexes with a low energy barrier8 and that [AuCl2(H2O)2]þ
can activate methane C-H bonds via a mechanism ana-
logous to that of the original Shilov system.9
On the basis of our longstanding activities within the field
of alkane C-H activation on electrophilic Pt(II) com-
plexes,10 the similarities between Periana’s Pt and Au cata-
lytic systems, and isoelectronic analogies between d8 Pt(II)
and Au(III) metal centers, we have initiated a program to
investigate the potential for C-H bond activation and
eventual catalytic functionalization of light alkanes in Au
systems. In a continuation of the analogies between Pt(II)
and Au(III), neutral Au(III) complexes which could provide
coordinatively labile Au(III) cationic species seemed to be a
reasonable initial target for establishing Au-based C-H
bond activation systems. Of the myriad of potentially fruitful
systems, our previous positive experience with cationic,
methane-activating diimine Pt(II) compounds10 led us to
choose N-ligated Au(III) complexes as our starting point,
The catalytic functionalization of alkanes is a particularly
challenging and active field of research, with the goal of a
sustainable, industrially viable route for the oxidation of
methane to methanol.1 Since Shilov and co-workers demon-
strated the ability of Pt(II)/Pt(IV) salts to catalytically con-
vert methane to methanol in aqueous media,2 there has been
increasing interest in both understanding the mechanism of
the Pt C-H activation process3 and finding new homo-
geneous oxidation catalysts for light alkanes.4 Particularly
relevant are the Pt system developed by Periana, which
operates in concentrated H2SO4 and elevated temperatures,5
*To whom correspondence should be addressed. Tel: þ 47 9824 3927.
Fax: þ 47 2206 7350. E-mail: richard.h.heyn@sintef.no.
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Goddard, W. A.; Goodman, D. W.; Keller, J.; Kubas, G. J.; Kung,
H. H.; Lyons, J. E.; Manzer, L. E.; Marks, T. J.; Morokuma, K.;
Nicholas, K. M.; Periana, R.; Que, L.; Rostrup-Nielson, J.; Sachtler,
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r
pubs.acs.org/Organometallics
Published on Web 04/23/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 10, 2010 2249
Scheme 1. Synthesis and Reactivity of 1
particularly since a range of Au(III) compounds bearing
nitrogen-based ligands are known.11 Of the potential candi-
dates, anionic β-diketiminato ligands, one of the most widely
used classes of nitrogen-donor ligands in organometallic
chemistry,12 were particularly intriguing. These ligands have
recently been employed in Au(I) chemistry. Shi et al. repor-
ted the use of β-diketiminato Au(I) species in the selective
aerobic oxidation of alcohols,13 and Dias et al. have synthe-
sized and structurally characterized the thermally stable,
dimeric gold(I) complexes {[HC{(H)C(2,4,6-Br3C6H2)N}2]-
Au}2 and {[HC{(H)C(Dipp)N}2]Au}2.14 Au(III) complexes
supported by β-diketiminato ligands are, however, unknown.
Herein, we present the synthesis, structure, and reactivity
studies on the first (β-diketiminato)gold(III) compound,
[HC{C(Me)N(C6H3-2,6-Me2)}2AuMe2].
for the carbon atoms of the Au-methyl groups appears at δ
4.8, while the signal for the methine carbon of the β-diketi-
minato backbone appears at δ 97.5.
Compound 1 crystallizes from a concentrated pentane
solution in the monoclinic space group P21/n. The gold atom
in 1 has a slightly distorted C2N2 square-planar coordination
geometry (Figure 1). The Au-C bond distances are 2.051(2)
and 2.055(2) A, which are in the range for typical AuIII-C
˚
bonds,17-19 and the C7-Au1-C6 angle is 84.13(9)° (see
Table 1 for selected bond distances and angles). The Au1-
˚
N1 and Au1-N2 distances are 2.1144(14) and 2.1210(15) A,
respectively, which are similar to other Au-N distances in
complexes where the N atom is trans to a C-based ligand.20
The atoms of the β-diketiminato backbone together with the
gold atom make a planar six-membered ring. The two
aromatic rings on the nitrogen atoms of the β-diketiminato
unit are perpendicular to this six-membered ring and face the
Au-bound methyl groups.
Results and Discussion
15
The salt metathesis reaction between [Me2AuCl]2 and
On the basis of our previous experience in related Pt
systems, it was of obvious interest to react 1 with acids, with
the goal of obtaining an open coordination site on Au via
protonolysis of a Au-Me bond. However, addition of 1
equiv of HOTf to 1 at -78 °C in acetonitrile led exclusively to
the protonation of the methine carbon of the β-diketiminato
unit, providing [H2C{C(Me)N(H3C6-2,6-Me2)}2AuMe2]-
[OTf] (2) (Scheme 1). This compound is thermally sensitive
and decomposes above 0 °C within 2 h both in the solid state
[HC{C(Me)N(C6H3-2,6-Me2)}2Li]16 resulted in the forma-
tion of [HC{C(Me)N(C6H3-2,6-Me2)}2AuMe2] (1) in 55%
yield (Scheme 1). Compound 1 is the first example of a
Au(III) compound bearing a β-diketiminato ligand, and it
has been characterized by NMR spectroscopy, mass spectro-
metry, and single-crystal X-ray diffraction studies. It is
soluble in hydrocarbon, ethereal, and chlorinated solvents.
It is air-stable but thermally sensitive, decomposing at room
temperature after 3 h both in the solid state and in solution. It
is, however, stable for more than 6 months when stored at
temperatures below -20 °C. The 1H NMR spectrum of 1 in
CD2Cl2 shows a single resonance at δ 0.02 for the protons of
the two Au-methyl groups, while the signal for the proton
on the methine carbon of the β-diketiminato backbone
appears at δ 4.94. In the 13C{1H} NMR spectrum, the signal
(17) Komiya, S.; Huffman, J. C.; Kochi, J. K. Inorg. Chem. 1977, 16,
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Titcombe, L. J. Organomet. Chem. 1985, 295, 401–405. (c) Schouteeten, S.;
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2250 Organometallics, Vol. 29, No. 10, 2010
Venugopal et al.
Figure 1. Crystal structures of compounds 1, 4, and 5 CH2Cl2. The triflate anions (CF3SO3-) in 4 and 5 and the solvent molecule
(CH2Cl2) in 5 are omitted for clarity. Atomic displacement parameters are shown at the 50% probability level.
3
˚
Table 1. Selected Bond Lengths (A) and Bond Angles (deg) for
observed even at -55 °C. Since the spectrum for a static boat
Compounds 1, 4, and 5 CH2Cl2
conformation should display nonequivalent methylene pro-
tons, this suggests that ring inversion of this presumed
conformation for 2 is fast on the NMR time scale. The
13C{1H} NMR spectrum of 2 shows a peak at δ 50.0 for
the methylene carbon on the β-diketiminato ligand. The
presence of the triflate anion in 2 was confirmed by a single
resonance at δ -78.3 in the 19F NMR spectrum.
3
1
4
5
Bond Lengths
Au1-C6
Au1-C7
Au1-N1
Au1-N2
Au2-C2
Au2-P1
I1-C2
2.055(2)
2.051(2)
2.041(2)
2.050(2)
2.045(2)
2.0435(19)
2.1349(14)
2.1285(14)
2.1381(16)
2.2691(4)
2.1144(14)
2.1210(15)
2.1616(16)
2.1607(16)
Treatment of 1 with 2 equiv of HOTf resulted in the forma-
tion of dimethylgold(III) triflate and the β-diketiminato triflate
salt [HC{C(Me)NH(H3C6-2,6-Me2)}2][OTf] (3) (Scheme 1).
The products crystallized from a dichloromethane solution as a
mixture and could not be separated. The identity of 3 was
2.1763(18)
Bond Angles
1
confirmed from comparison of the H NMR spectrum of
C7-Au1-C6
N1-Au1-N2
C6-Au1-N1
C7-Au1-N2
C1-N1-Au1
C3-N2-Au1
C2-Au2-P1
84.13(9)
90.56(6)
92.48(7)
93.00(8)
124.50(12)
124.04(12)
84.07(9)
88.90(6)
92.81(8)
94.20(8)
123.77(13)
124.43(13)
84.89(8)
89.03(5)
93.43(7)
92.65(7)
123.19(12)
122.92(11)
172.11(5)
the mixture with that from an independent reaction of the
β-diketimine (2,6-Me2H3C6)NHC(CH3)CHC(CH3)N(C6H3-
2,6-Me2) and triflic acid. The signal for the methyl protons of
1
Me2AuOTf appears at δ 1.38 in the H NMR spectrum, in
agreement with the literature.17
Since I2 is reported to react with (β-diketiminato)metal
alkyls to give the corresponding (β-diketiminato)metal
iodide,23 1 was treated with 1 equiv of I2 in diethyl ether at
-55 °C. This led to the formation of an orange precipitate,
which was further reacted in situ with 1 equiv of AgOTf to
provide [HC(I){C(Me)N(C6H3-2,6-Me2)}2AuMe2][OTf] (4)
(Scheme 1). Decomposition occurs if the temperature of the
reaction mixture exceeds 10 °C. However, once isolated, 4 is
stable at ambient temperature in the solid state, and it was
characterized by multinuclear NMR spectroscopy, elemen-
tal analysis, mass spectrometry, and single crystal X-ray
diffraction studies and quantum-chemical calculations. To
the best of our knowledge, this is the first example of a
reaction where a halogen atom binds to the γ-carbon in a
metal β-diketiminate complex.
and in solution. There are only a few examples of late-
transition-metal complexes where the methine carbon of
the β-diketiminato unit is protonated as in 2.21 Another
potential Me- abstraction reagent,22 B(C6F5)3, did not react
with 1. Treatment of 1 with excess trifluoroethanol in the
presence of acetonitrile also did not lead to the protonation
of the Au-bound methyl group.
The identity of 2 was deduced by 1H and 13C{1H} NMR
1
spectroscopy. In the H NMR spectrum, the signal for the
protons of the Au-methyl groups is at δ 0.56, at lower field
as compared to the corresponding signal in 1. The signal for
the protons of the methyl groups on the β-diketiminato
ligand also appear at lower field as compared to those in 1,
at δ 2.30. The signal for the two methylene protons in 2
appears as a sharp singlet at δ 4.34, and no broadening is
(23) (a) Schulz, S.; Eisenmann, T.; Westphal, U.; Schmidt, S.; Florke,
U. Z. Anorg. Allg. Chem. 2009, 635, 216–220. (b) Stender, M.; Eichler,
B. E.; Hardman, N. J.; Power, P. P.; Prust, J.; Noltemeyer, M.; Roesky, H. W.
Inorg. Chem. 2001, 40, 2794–2799.
(21) Feldman, J.; McLain, S. J.; Parthasarathy, A.; Marshall, W. J.;
Calabrese, J. C.; Arthur, S. D. Organometallics 1997, 16, 1514–1516.
(22) Erker, G. Dalton Trans. 2005, 1883–1890.

Article
The composition of the cation [HC(I){C(Me)N(C6H3-2,6-
Organometallics, Vol. 29, No. 10, 2010 2251
reported in this paper, compound 5 has a high thermal
stability and shows no decomposition even after heating
for 8 h at 70 °C in acetonitrile. Compound 5 was character-
ized by NMR spectroscopy, elemental analysis, and single-
crystal X-ray diffraction studies. The most diagnostic
feature in the NMR spectra is the coupling of the phos-
phorus atom to both the γ-carbon and its accompanying
Me2)}2AuMe2]þ was confirmed by mass spectrometry with
the presence of a molecular ion peak at m/z 659.2. The
chemical shift for the proton on the iodine-bearing γ-carbon
atom is δ 6.05, and there is no detectable signal broadening in
the 1H spectrum of 4, even upon cooling to -55 °C. Unlike
the rapid ring inversion in 2, which equilibrates the environ-
ments of the ostensibly inequivalent methylene protons, this
observation suggests that the AuN2C3 ring in 4 is restricted to
one conformation, although rapid interconversion between
two conformers cannot be ruled out. Optimization of a hypo-
thetical conformer with the I atom in an equatorial position
converged to a well-defined minimum with an energy 7.4 kcal/
mol higher than the conformer with I in an axial position. This
may be taken as the minimum value for the activation energy
for conformer interconversion, although the activation energy
is most probably considerably higher. A transition state opti-
mization was not carried out. Correspondingly, the signals for
the aromatic methyl groups appear as two singlets of equal
intensity, due to the inequivalence between the top and bottom
halves of 4. The 13C signal of the γ-carbon appears at δ 26.8,
and this strong shift of 23.2 ppm to higher field, in comparison
to 2, is consistent with the substituent chemical shift for CR
observed upon substitution of I for H.24
proton, with coupling constants of 2JPC=48.2 Hz and 3JPH
=
9.8 Hz.
Compound 5 crystallizes along with one molecule of
dichloromethane in the triclinic space group P1 (Figure 1).
The six-membered AuN2C3 ring in 5 also adopts a boat
conformation like that of 4, with the (PPh3)AuI moiety also
in the axial position of the apical C2 atom. The coordination
geometry around Au2 is nearly linear, with a P1-Au2-C2
angle of 172.1(1)°. The Au2-P1 and Au2-C2 distances are
within the range of Au-P and Au-C distances found in the
literature.28 The Au2 atom is tilted even more toward Au1
than that observed with the I atom in 4; the Au1-C2-Au2
angle is acute (83.72°), about 10° less than the analogous
˚
angle in 4. The Au-Au distance is 3.742 A, which is,
however, far greater than the typical Au-Au interactions
29
˚
(3.00 ( 0.25 A).
Despite the cationic nature of 5, numerous attempts to
abstract the proton on the γ-carbon atom with a variety of
bases failed. Reaction between 5 and triethylamine in di-
chloromethane-d2 led to the formation of [PPh3Au(NEt3)]þ
and 1. Similarly, 5 reacted with KOtBu to displace
(PPh3)AuOtBu. However, no reactivity was observed when
5 was mixed with 2,6-di-tert-butylpyridine in dichloro-
methane-d2 and heated to 75 °C for 8 h in a sealed tube.
Reaction of 5 with other bases in a variety of solvents and at a
variety of temperatures (from ambient to -78 °C) gave either
no reaction or loss of the (PPh3)Au moiety.
Compound 4 crystallizes in the orthorhombic space group
P212121 (Figure 1). The atom Au1 is, as expected, bonded to
two nitrogen atoms of the diketimine ligand and two methyl
carbon atoms in a square-planar arrangement. Gratifyingly,
a quantum-chemical geometry optimization and a single-
crystal X-ray diffraction experiment lead to very similar
structures for 4. In the following, geometry parameters are
given as xx {yy}, where xx and yy are the experimental and
calculated values, respectively. The six-membered AuN2C3
ring adopts a boat conformation, with I1 in an axial position
on the apical C2 atom. The I1-C2-Au1 angle is 92.88°
˚
˚
Conclusion
{90.1°}, and the Au1-I1 distance is 4.074 A {4.05 A}, which
˚
is 0.48 A longer than the sum of the van der Waals radii. The
We have successfully introduced the β-diketiminato ligand
onto a gold(III) center and obtained the complex [HC{C-
(Me)N(C6H3-2,6-Me2)}2AuMe2] (1), which is the first exam-
ple of a β-diketiminato-ligated Au(III) compound. Given the
hypothesis that a coordinatively labile, electrophilic Au(III)
center is capable of alkane C-H activation, reactivity studies
focused on synthesis of a cationic gold(III) species of the type
[(β-diketiminato)Au(Me)(L)]þ, via reaction of 1 with elec-
trophiles. However, all results showed that the site of elec-
trophilic attack is not the Au-C bond but rather the
γ-carbon of the diketiminato ligand. Thus, triflic acid proto-
nated the γ-carbon of the diketiminato unit, whereas reac-
tion of 1 with both I2 and the inorganic electrophile PPh3-
AuCl provided the unique cationic gold(III) compounds
4 and 5. Crystallographic studies indicate the six-mem-
bered AuN2C3 ring in 1 is planar while the corresponding
rings in 4 and 5 assume boat conformations, with the
attacking electrophiles oriented axially from the apical
γ-carbon.
˚
˚
I1-C2 distance is 2.1763(18) A {2.24 A}. The angle between
the two planes formed by the basal atoms N1, N2, C1, and
C3 is 4.10° {0.7°}. Au1 and the γ-carbon C2 lie above this
distorted plane with torsion angles of 36.7(3)° {44.5°} for
N1-C1-C2-C3 and 19.5(2)° {27.4°} for N1-Au1-N2-C3.
The reactivity of 1 with HOTf and I2 demonstrates that the
methine carbon of the β-diketiminato ligand is nucleophilic
enough to be the primary site of electrophilic attack, while
the Au-methyl bonds remain inert. This observation sug-
gested the potential of attaching electrophilic inorganic frag-
ments to the methine carbon in 1. Since (phosphino)gold(I)
cations [(R3P)Au]þ are isolobal with Hþ,25 1 was reacted
with PPh3AuCl in the presence of AgOTf. This reaction
provided [HC{AuPPh3}{C(Me)N(C6H3-2,6-Me2)}2AuMe2]-
[OTf] (5), in which [PPh3Au]þ is indeed bound to the afore-
mentioned methine carbon (Scheme 1). While the vast majo-
rity of known AuI AuIII compounds are isomers of dimeric
3 3 3
AuII-AuII ylide compounds,26 5 more closely resembles the
structurally uncharacterized complex [{(Ph2P)2CH(Au-
PPh3)}Au{C6F5}2][ClO4].27 Unlike the other gold compounds
Due to the inability to obtain any data indicating even a
hint of Au-C bond cleavage in 1, other studies, such as the
thermal stability of 1 in acidic solvents or the reactivity of 1
directly with hydrocarbons, have not been carried out. We
(24) Wiberg, K. B.; Pratt, W. E.; Bailey, W. F. J. Org. Chem. 1980, 45,
4936–4947.
(25) Schmidbaur, H. Chem. Soc. Rev. 1995, 24, 391–400.
(26) Fackler, J. P. Inorg. Chem. 2002, 41, 6959–6972.
(27) Fernandez, E. J.; Gimeno, M. C.; Jones, P. G.; Laguna, A.;
Laguna, M.; Lopez-de-Luzuriaga, J. M. J. Chem. Soc., Dalton Trans.
1992, 3365–3370.
(28) Laguna, A., Gold Compounds of Phosphorus and the Heavy
Group V. In Gold-Progress in Chemistry, Biochemistry and Technology;
Schmidbaur, H., Ed.; Wiley: Chichester, U.K., 1999; pp 349-427.
(29) Schmidbaur, H.; Schier, A. Chem. Soc. Rev. 2008, 37, 1931–1951.

2252 Organometallics, Vol. 29, No. 10, 2010
Venugopal et al.
have rather turned our investigations toward other poten-
tially fruitful Au(III) systems for alkane C-H activation,
and the results of these studies will be presented in due
course.
Table 2. Selected Crystallographic Data and Refinement Para-
meters for Compounds 1, 4, and 5 CH2Cl2
3
1
4
5 CH2Cl2
3
formula
C23H31AuN2
C24H31AuF3-
IN2O3S
808.43
orthorhombic
P212121
11.1621(8)
12.8960(9)
19.3602(13)
C
43H48Au2-
Cl2F3N2O3PS
Experimental Section
fw
cryst syst
space group
532.46
monoclinic
P21/n
13.3580(13)
13.1952(13)
13.473(13)
1225.70
triclinic
P1
General Considerations. All manipulations were performed
under an argon atmosphere using Schlenk techniques. All
solvents were dried and distilled by standard methods prior to
use. The starting materials [Me2AuCl]2,15 [{(2,6-Me2H3C6)N-
(CH3)C}2CH]Li,16 and (Ph3P)AuCl30 were synthesized accord-
ing to literature procedures. HOTf, I2, and AgOTf were
purchased from Sigma-Aldrich and used as received. NMR
measurements were made on a 300 MHz Gemini spectrometer,
and chemical shifts are represented in ppm, referenced to the
residual proton signals of the deuterated solvents. The mass
spectra were obtained using a Micromass Q-TOF 2 spectro-
meter. Elemental analyses were carried out by the Mikroana-
˚
a (A)
10.4621(3)
13.3464(4)
15.9891(4)
92.5025(30)
92.2262(3)
101.4406(3)
2183.56(11)
2
1.864
6.972
31.54
0.0254
13 452
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
116.401(1)
3
˚
V (A )
Z
2127.3(4)
4
2786.8(3)
4
dcalcd (Mg m-3
)
1.663
6.924
33.24
0.0369
7470
1.927
6.509
31.65
0.0397
8991
μ (mm-1
)
θ
max (deg)
R(int)
no. of rflns
€
lytisches Labor H. Kolbe, Mulheim, Germany. The samples
for elemental analysis were dried under vacuum (10-3 mbar)
for 12 h.
with I>2σ(I)
R1 (I>2σ(I))
wR2 (all data)
0.0207
0.0556
0.0139
0.0402
0.0180
0.0468
Compound 1. A solution of [Me2AuCl]2 (0.100 g, 0.38 mmol)
in 15 mL of pentane was added to a suspension of [{(2,6-
Me2H3C6)N(CH3)C}2CH]Li (0.116 g, 0.38 mmol) in 25 mL of
pentane at -78 °C. The reaction mixture was warmed to 10 °C
over 5 h and was stirred for a further 15 h at this temperature.
The resulting mixture was filtered, and the solution was con-
centrated to precipitate pale yellow crystals of 1. Yield: 55%.
Thermal instability prevented collection of elemental analysis
data. 1H NMR (CD2Cl2; 300 MHz): δ 7.16 (d, J=8.1 Hz, 4H,
m-Ar H), 6.98 (t, J=8.1 Hz, 2H, p-Ar H), 4.94 (s, 1H, γ-CH),
2.18 (s, 12H, Ar-CH3), 1.60 (s, 6H, C-CH3), 0.02 (s, 6H,
Au-CH3). 13C{1H} NMR (CD2Cl2; 75 MHz): δ 159.0, 148.5,
133.2, 128.0, 125.6, 97.5 (γ-CH), 25.0 (C-CH3), 18.6 (Ar-
CH3), 4.8 (Au-CH3). TOF MS ES: m/z 533.2 [Mþ], 503.2
[Mþ - 2 Me], 279.0, 98.5, 89.5.
15 mL of dichloromethane at 0 °C. AgOTf (0.025 g, 0.1 mmol)
was then added to this solution, and the resulting reaction
mixture was stirred at 0 °C for 1 h. The reaction mixture was
thereafter filtered, concentrated to 3 mL, layered with 12 mL of
diethyl ether, and stored at -45 °C, which provided yellow
crystals of 3. Yield: 67%. 1H NMR (CD2Cl2; 300 MHz): δ 7.21
(br, 6H, Ar H), 6.05 (s, 6H, γ-CH), 2.38 (s, 6H, C-CH3), 2.24 (s,
6H, Ar-CH3), 2.21 (s, 6H, Ar-CH3), 0.58 (s, 6H, Au-CH3).
13C{1H} NMR (CD2Cl2; 75 MHz): δ 180.9, 143.0, 131.2,
130.3, 130.0, 129.4, 128.4, 26.8 (γ-CH), 23.8 (C-CH3), 18.8
(Ar-CH3), 18.5 (Ar-CH3), 7.1 (Au-CH3). 19F NMR (CD2Cl2;
282 MHz): δ -78.3. TOF MS ESþ: m/z 659.2 [Mþ - OTf]. Anal.
Calcd for C24H31AuF3IN2O3S: C, 35.7; H, 3.83; N, 3.46. Found:
C, 35.5; H, 3.84; N, 3.46.
Compound 2. A 1 mL portion of a 0.1 M acetonitrile solution
of triflic acid (0.1 mmol) was added dropwise to a dichloro-
methane solution of 1 (0.053 g, 0.1 mmol) at -78 °C. The
reaction mixture was warmed to 10 °C over 5 h and was stirred
for a further 5 h at this temperature. The solvent was removed
under vacuum, leaving behind a pale yellow residue of 2. Yield:
71%. Thermal instability prevented collection of elemental
Compound 5. A 15 mL portion of THF was added to a mixture
of 1 (0.053 g, 0.1 mmol), (Ph3P)AuCl (0.049 g, 0.1 mmol), and
AgOTf (0.025 g, 0.1 mmol), and the reaction mixture was stirred
at room temperature for 15 h while being protected from light.
The reaction mixture was then filtered, and the solvent was
removed under vacuum. The resulting oily residue was dissolved
in 2 mL of dichloromethane and layered with 10 mL of diethyl
ether, after which 5 crystallized at room temperature as colorless
needles. Yield: 65%. 1H NMR (CD2Cl2; 300 MHz): δ 7.64-7.43
1
analysis data. H NMR (CD2Cl2; 300 MHz): δ 7.19 (br, 6H,
Ar H), 4.34 (s, 2H, γ-CH2), 2.30 (s, 6H, C-CH3), 2.21 (s, 12H,
Ar-CH3), 0.56 (s, 6H, Au-CH3). 13C{1H} NMR (CD2Cl2; 75
MHz): δ 180.2, 143.0, 130.3, 129.8, 128.1, 50.0 (γ-CH2), 25.2
(C-CH3), 18.4 (Ar-CH3), 6.2 (Au-CH3). TOF MS ES: m/z
534.3 [Mþ - OTf], 533.2, 503.2, 307.2.
(15 H, PPh3), 7.19 (t, 3JHH=8.5 Hz, 2H, p-Ar H), 7.10 (d, 3JHH
=
8.5 Hz, 4H, m-Ar H), 4.49 (d, 3JHP=9.8 Hz, 1H, γ-CH), 2.22 (s,
6H, C-CH3), 2.09 (s, 6H, Ar-CH3), 1.90 (s, 6H, Ar-CH3), 0.38
(s, 6H, Au-CH3). 31P NMR (CD2Cl2; 121 MHz): δ 42.0 (br).
13C{1H} NMR (CD2Cl2; 75 MHz): δ 186.4, 144.1, 134.6 (d,
Compound 3. A 2 mL portion of a 0.1 M acetonitrile solution
of triflic acid (0.2 mmol) was added dropwise to a dichloro-
methane solution of 1 (0.053 g, 0.1 mmol) at -78 °C. The
reaction mixture was warmed to 10 °C over 5 h and was stirred
for a further 5 h. The solvent was removed under vacuum,
leaving behind a pale yellow residue of 3 and [Me2AuOTf], a
mixture of which was crystallized from a mixture of dichloro-
4
2JPC=13.6 Hz, Co, PPh3), 133.1 (d, JPC=2.6 Hz, Cp, PPh3),
131.6, 130.1 (d, 3JPC=11.5 Hz, Cm, PPh3), 129.1(d, 1JPC=65.0
Hz, Ci, PPh3), 128.3, 127.6, 127,2, 69.7 (d, 2JPC=48.2 Hz, γ-CH),
25.6 (C-CH3), 19.5 (Ar-CH3), 19.3 (Ar-CH3), 5.9 (Au-CH3).
19F NMR (CDCl2; 282 MHz): δ -78.2. TOF MS ESþ: m/z 991.2
[Mþ - OTf], 500.1. Anal. Calcd for C42H46Au2F3N2O3PS: C,
44.2; H, 4.03; N, 2.45. Found: C, 44.5; H, 3.95; N, 2.46.
1
methane and diethyl ether at 10 °C. H NMR (CD2Cl2; 300
MHz): δ 8.74 (br s, 2H, NH), 6.98 (t, 3JHH=8.8 Hz, 2H, p-Ar H),
6.82 (d, 3JHH=8.8 Hz, 4H, m-Ar H), 4.25 (s, 1H, γ-CH), 2.61 (s,
6H, C-CH3), 1.60 (s, 12H, Ar-CH3), 1.38 (s, 6H, [(CH3)2-
AuOTf]). 19F NMR (CD2Cl2; 282 MHz): δ -78.5.
Single-Crystal X-ray Diffraction Experiments. Single crystals
of 1, 4, and 5 CH2Cl2 suitable for X-ray diffraction measure-
3
ments were obtained by repeated crystallization of the corres-
ponding products isolated from the reaction mixtures. Selected
crystallographic data and refinement parameters are collected
in Table 2. The crystals were suspended in Paratone-N oil
(Hampton Research), mounted on a glass fiber and thereafter
placed onto the goniometer under a cold stream. The measure-
ments were carried out on a Bruker APEX-II CCD ULTRA
rotating anode diffractometer using graphite-monochromated
Compound 4. Iodine (0.023 g, 0.1 mmol) was added to a
diethyl ether solution of 1 (0.053 g, 0.1 mmol) at -78 °C. The
reaction mixture was warmed to 0 °C over 3 h, and the solvent
was evaporated under vacuum. The residue was dissolved in
(30) Braunstein, P.; Lehner, H.; Matt, D. Inorg. Synth. 1990, 27,
218–221.
˚
Mo KR radiation (λ=0.710 73 A), performing 182° ω scans in

Article
Organometallics, Vol. 29, No. 10, 2010 2253
four j positions. Raw data were collected using the APEX2
software packages,31 reduced, and scaled with the program SAINT.
The structures were solved by direct methods and refined by full-
matrix least-squares cycles (SHELXS97, SHELXTL-97).32 The
structures in this article are represented using the program OR-
TEP-III.33 Crystallographic data (excluding structure factors) for
the structures reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary pub-
multielectron adjusted quasirelativistic effective core potential
covering 60 electrons ([Kr]4d104f14) and an 8s7p6d/[6s5p3d]-
GTO valence basis set (31111, 22111, 411, 21) was used.35 To
further improve the quality of the basis set, f-type polarization
functions for gold were optimized by choosing three exponents
√
in an even-tempered fashion: i.e., separated by factors of 5.
CCSD(T) calculations were carried out for the gold atom in its
doublet S ground state, and the energy was minimized by
varying the f-type exponents, keeping the ratios between them
constant. Hence, only one parameter was optimized. Finally,
the three optimized primitive functions were contracted
to two using a (21) scheme, taking the contraction coeffici-
ents from the atomic calculation (see the Supporting Infor-
mation). C, H, and N atoms were described with the Dunning
correlation consistent cc-pVDZ and basis sets,36 while the
LANL2DZ ECP and valence basis37 were employed for
iodine.
lications no. 759373 (1), 759374 (4), and 759375 (5 CH2Cl2).
3
Copies of the data can be obtained from the CCDC, 12 Union
Road, Cambridge CB2 1EZ, U.K. (fax, (þ44)1223-336-033;
e-mail, deposit@ccdc.cam.ac.uk).
Quantum-Chemical Calculations. Geometry optimizations
were carried out using the B3LYP density functional as imple-
mented in the Gaussian 03 program system.34 For gold, a
(31) APEX Software Suite, v. 2.1-4 and SAINT v. 7.53A, Data
Integration Software for Bruker AXS CCD; Bruker AXS, Inc., Madison,
WI, 2008.
Acknowledgment. We thank the GASSMAKS pro-
gram of the Norwegian Research Council (Grant No.
185513/I30) for generous financial support, the NOTUR
project for a grant of computing resources (http://www.
notur.no, Acc. No. NN2147k), Aud Mjærum Bouzga for
assistance with the NMR spectroscopy, and Dr. Anthony
P. Shaw for helpful discussions.
(32) Sheldrick, G. M. SHELXS97 and SHELXTL-97. Acta Crystal-
logr. 2008, A64, 112–122.
(33) Burnett, M. N.; Johnson, C. K. ORTEP-III: Oak Ridge Thermal
Ellipsoid Plot Program for Crystal Structure Illustrations; Report ORNL-
6895; Oak Ridge National Laboratory, Oak Ridge, TN, 1996.
(34) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.;
Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;
Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,
G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken,
V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,
O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.;
Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.;
Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas,
O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.;
Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.;
Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Gonzalez, C.; Pople, J. A. Gaussian 03, revision E.01; Gaussian, Inc.,
Wallingford, CT, 2003.
Supporting Information Available: A table giving optimized
F-type basis functions for gold and CIF files for the crystal
structures of 1, 4, and 5 CH2Cl2. This material is available free
of charge via the Internet at http://pubs.acs.org.
3
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