Three-coordinated aminotroponiminate and aminotroponate complexes of gold(I)

Article abstract of DOI:10.1021/ic0701662

Potassium N-isopropyl-2-(isopropylamino)troponiminate, K{(/Pr) ₂ATl}, and potassium N-cyclohexyl-2-(cyclohexylamino)troponiminate, K{(Cy)₂ATl}, were synthesized by treatment of the neutral ligands with an excess of KH in THF. Reactio

Full text of DOI:10.1021/ic0701662

Inorg. Chem. 2007, 46, 4599−4604
Three-Coordinated Aminotroponiminate and Aminotroponate Complexes
of Gold(I)
Jenni Meiners, Jost-Steffen Herrmann, and Peter W. Roesky*
Institut fu¨r Chemie und Biochemie, Freie UniVersita¨t Berlin, Fabeckstrasse 34-36,
14195 Berlin, Germany
Received January 30, 2007
Potassium N-isopropyl-2-(isopropylamino)troponiminate, K
lamino)troponiminate, K (Cy)2ATI , were synthesized by treatment of the neutral ligands with an excess of KH in
THF. Reaction of the potassium reagents with [AuClPPh3] resulted in the gold complexes [Au (iPr)2ATI PPh3] and
[Au (Cy)2ATI PPh3]. The solid-state structures of both compounds, in which the ligands are arranged in plane,
{(iPr)2ATI}, and potassium N-cyclohexyl-2-(cyclohexy-
{
}
{
}
{
}
show distorted trigonal planar coordinated gold atoms. Potassium 2-(isopropylamino)troponate (K(iPrAT)) and the
cyclohexyl analogue (K(CyAT)) were obtained by deprotonation of corresponding aminotropones with KH. In an
analogous fashion the gold complexes of composition [Au(iPrAT)PPh3] and [Au(CyAT)PPh3] were prepared by
reaction of K(iPrAT) and K(CyAT) with [AuClPPh3], respectively.
Introduction
As a result of the strong tendency of gold(I) toward a 2-fold
coordination, the number of complexes with higher coordina-
tion numbers is still low.8,9 Most of the three-coordinated
complexes have phosphine ligands in the coordination sphere.
The maybe most prominent examples in this series are the
trisphosphine cations [Au(PR3)3]+.10 Three-coordinated mono-
phosphine complexes were obtained by using bidentate
ligands although the strong tendency of gold(I) to form linear
complexes may force the bidentate ligand into an asymmetric
coordination mode as it is observed for the cation [Au(PPh3)-
(bipy)]+ (bipy ) 2,2′-bipyridine),11 [Au(PPh3)(Me2NCH2CH2-
NMe2)]BF4,12 and the 2,9-dimethyl-1,10-phenanthroline
(dmphen) gold(I) complex [Au(C6H2(NO2)-2,4,6)(dmphen)]
((C6H2(NO2)-2,4,6) ) 2,4,6-trinitrophenyl).13 Even though
a four-coordinated tris(pyrazolylborato)(triphenylphosphine)-
gold(I) complex is known,14 there are to the best of our
Beside the challenges in synthetic chemistry gold(I)
compounds1 are also of interest for photophysical,2-4 cata-
lytic,5 and pharmaceutical6 applications. Although the co-
ordination chemistry of gold phosphine compounds has
been investigated intensively, the factors influencing the
coordination number of gold are not so well understood.7
* To whom correspondence should be addressed. E-mail: roesky@
chemie.fu-berlin.de.
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10.1021/ic0701662 CCC: $37.00
Published on Web 05/05/2007
© 2007 American Chemical Society
Inorganic Chemistry, Vol. 46, No. 11, 2007 4599

Meiners et al.
Scheme 1
Scheme 2
K{CH(PPh2NSiMe3)2} with [AuClPPh3] gave the diaurated
gold complex [(Ph3PAu)2{C(PPh2NSiMe3)2}], in which the
two gold atoms are coordinated in a linear fashion onto the
ligand backbone.34 Moreover, Au(I)-Au(I) contacts are
observed (Scheme 2).
Therefore, we intended to introduce a more rigid N,N-
bidentate monoanionic ligand system into gold(I) chemistry.
Herein we report on the coordination of aminotroponiminate
ligands (D) (Scheme 1) onto gold(I) leading to trigonal planar
complexes. Moreover we also coordinated aminotroponate
ligands (E) related N,O-bidentate monoanionic ligands onto
gold(I). In this context the N,O-chelating donor quinolin-8-
olate was used earlier for the synthesis of a dinuclear gold-
(I) complex.35 Whereas aminotroponiminate36 and ami-
notroponate complexes37-39 of some main group and transition
metals are known, to the best of our knowledge no gold
complexes were reported so far.
knowledge no three-coordinated gold(I) complexes bearing
N,N′-bidentate anionic ligand systems in the coordination
sphere.
Whereas N,N′-bidentate monoanionic ligand systems15
such as â-diiminate (â-diketiminato) (A)16-19 or benzamidi-
nates (B)20 have been used recently in coordination
chemistry to stabilize reactive metal centers (Scheme 1),
gold(I) complexes of these ligands are not known. We
recently wanted to introduce bis(phosphinimino)methanide
({CH(PPh2NSiMe3)2}-) (C), a P-N ligand system, which
is topologically related to the â-diiminate ligands, in gold-
(I) chemistry. In most of the solid-state structures a six-
membered metallacycle (N1-P1-C1-P2-N2-M) is formed
by chelation of the two trimethylsilylimine groups to the
metal center. Moreover, the methine carbon atom of the bis-
(phosphinimino)methanide ligand coordinates via a long-
range interaction onto the metal atom;21-33 thus, the metal-
lacycle adopts a pseudoboat conformation. To our surprise
we did not isolate a complex, in which the nitrogen atoms
coordinate to the metal atom, but instead the reaction of
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4600 Inorganic Chemistry, Vol. 46, No. 11, 2007

AuI Aminotroponiminate and Aminotroponate Complexes
459.4 (0.1) [M - iPr2AT]+, 262.1 (100) [PPh3]+. Anal. Calcd for
C31H34AuN2P (Mr ) 662.56): C, 56.20; H, 5.17; N, 4.23. Found:
C, 55.81; H, 4.94; N, 3.78.
Experimental Section
General Methods. All manipulations of air-sensitive materials
were performed with the rigorous exclusion of oxygen and moisture
in flame-dried Schlenk-type glassware either on a dual manifold
Schlenk line, interfaced to a high-vacuum (10-4 Torr) line, or in
an argon-filled M. Braun glovebox. THF was predried over Na
wire and distilled under nitrogen from K and benzophenone ketyl
prior to use. Hydrocarbon solvents (toluene and n-pentane) were
distilled under nitrogen from LiAlH4. All solvents for vacuum
line manipulations were stored in vacuo over LiAlH4 in
resealable flasks. Deuterated solvents were obtained from
Chemotrade Chemiehandelsgesellschaft mbH or Euriso-Top GmbH
(all g99 atom % D) and were degassed, dried, and stored in vacuo
over Na/K alloy in resealable flasks. NMR spectra were recorded
on JNM-LA 400 FT-NMR spectrometer. Chemical shifts are
referenced to internal solvent resonances and are reported relative
to tetramethylsilane and 85% phosphoric acid (31P NMR), respec-
tively. Elemental analyses were carried out with an Elementar
vario EL or EL III. (CyAT)H,40 {(Cy)2ATI}H,40 K(iPrAT),41
K{(iPr)2ATI},42 and [AuClPPh3]43 were prepared according to
literature procedures.
[Au{(Cy)2ATI}PPh3] (2). Under exclusion of light and under
stirring, 25 mL of THF was dropped into a mixture of 0.508 g
(1.03 mmol) of [AuClPPh3] and 0.340 g (1.06 mmol) of K(Cy2-
ATI) at 0 °C. The solution was slowly warmed to room temperature,
and the mixture was stirred for 18 h. The solvent was removed in
vacuo, and the remaining orange solid was extracted with 75 mL
of toluene. The extract was reduced to dryness. The remaining dark
beige solid was washed with 50 mL of pentane and dried in vacuo
resulting in a light-sensitive light yellow powder. Yield: 471 mg
1
(62%). Mp: 130 °C (dec). H NMR (THF-d8, 400 MHz, RT): δ
) 0.76-0.90 (m, 2 H), 1.27-1.40 (m, 4 H), 1.44-1.62 (m, 10 H),
1.70-1.80 (m, 4 H), 3.72-3.84 (m, 2 H, 2 NCHCy), 5.81 (t, 1 H,
3
3JH,H ) 8.9 Hz), 6.25 (d, 2 H, JH,H ) 11.8 Hz), 6.75 (dd, 2 H,
3JH,H ) 11.8 Hz. 8.9 Hz), 7.41-7.48 (m, 9 H, 9 CHPh o/p), 7.59-
7.67 (m, 6 H, 6 CHPh m). 13C{1H} NMR (THF-d8, 110.4 MHz,
RT): δ ) 26.5, 26.6, 36.5, 59.2, 109.2, 113.8, 129.4 (d, CHPh m,
4
3JC,P ) 11.2 Hz), 131.4 (d, CHPh p, JC,P ) 2.1 Hz), 132.9 (C4,6),
134.8 (d, CHPh o, 4JC,P ) 13.6 Hz), 134.8 (d, CHPh i, 1JC,P ) 54.6
Hz), 161.9 (C1,2). 31P{1H} NMR (THF-d8, 161.7 MHz, RT): δ )
34.2. MS (80 eV, EI, 30 °C): m/z (%) ) 742.3 (2.7) [M]+, 262.1
(52) [PPh3]+, 182.8 (100) [PPh2]+. Anal. Calcd for C31H34AuN2P
(Mr ) 742.68): C, 59.84; H, 5.70; N, 3.77. Found: C, 59.14; H,
5.32; N, 3.50.
K{(Cy)2ATI}. A 90 mL volume of THF was slowly added to a
mixture of 3.71 g (13.0 mmol) of H(Cy2ATI) and 0.980 g (24.4
mmol) of KH at room temperature, and the mixture was stirred for
18 h at room temperature. The solution was then filtered, and the
remaining residue was extracted with 25 mL of THF. The solvent
was removed in vacuo, and the muddy-yellowish solid was washed
with pentane (2 × 50 mL) to obtain a light yellow, fine powder.
K(CyAT). A 0.354 g (1.74 mmol) amount of (CyAT)H dissolved
in 8 mL of THF was added to 0.120 g (2.99 mmol) of KH at room
temperature, and the mixture was stirred for 18 h at room
temperature. The solution was then filtered, and the remaining
residue was extracted with THF (3 × 3 mL). The solvent of the
combined extracts was removed in vacuo to obtain a fine light
1
Yield: 3.25 g (78%). H NMR [THF-d8, 400 MHz, RT (room
temperature)]: δ ) 1.06-1.24 (m, 6 H), 1.35-1.48 (m, 4 H), 1.64-
1.79 (m, 6 H), 1.81-1.90 (m, 4 H), 3.31 (tt, 2 H, 2 NCHCy, 3JH,H
3
) 10.8 Hz, 3.2 Hz), 5.05 (t, 1 H, JH,H ) 8.7 Hz), 5.50 (d, 2 H,
3JH,H ) 11.3 Hz), 6.17 (dd, 2 H, JH,H ) 11.3 Hz, 8.7 Hz). 13C-
3
1
yellow powder. Yield: 282 mg (67%). H NMR (THF-d8, 400
{1H} NMR (THF-d8, 110.4 MHz, RT): δ ) 25.9, 26.9, 35.5, 59.8,
103.7, 103.8, 131.7, 163.0 (C1,2).
MHz, RT): δ ) 1.05-1.45 (m, 5 H), 1.50-1.81 (m, 5H), 3.26
(m, 1 H, NCHCy), 5.69 (dd, 1 H, 3JH,H ) 8.5 Hz, 8.2 Hz), 6.13 (d,
1 H, 3JH,H ) 10.6 Hz), 6.27 (d, 1 H, 3JH, H ) 11.6 Hz), 6.39-6.56
(m, 2 H). 13C{1H} NMR (THF-d8, 110.4 MHz, RT): δ ) 26.5,
26.9, 34.7 (NCHCH2(Cy)), 58.7 (NCHCy), 112.9, 114.4, 115.0,
132.6, 134.2, 164.7 (C2), 180.2 (C1).
[Au{(iPr)2ATI}PPh3] (1). Under exclusion of light and under
stirring, 50 mL of THF was dropped into a mixture of 925 mg
(1.87 mmol) of [AuClPPh3] and 472 mg (1.89 mmol) of K{-
(iPr)2ATI} at -40 °C. The solution was slowly warmed to room
temperature, and the mixture was stirred for 18 h. The solvent was
removed in vacuo, and the remaining orange solid was extracted
with toluene (2 × 50 mL). The reddish extract was reduced to
dryness. The remaining solid was washed several times with pentane
(100 mL) and dried in vacuo. A light-sensitive yellow powder was
obtained. Yield: 1.16 g (94%). Mp: 124 °C (dec). 1H NMR (THF-
d8, 400 MHz, RT): δ ) 1.16 (d, 12 H, 2 NCH(CH3)2, 3JH,H ) 6.1
Hz), 4.17 (sept, 2 H, 2 NCH(CH3)2, 3JH,H ) 6.1 Hz), 5.81 (t, 1 H,
[Au(iPrAT)PPh3] (3). Under exclusion of light and under
stirring, 30 mL of THF was dropped into a mixture of 0.727 g
(1.47 mmol) of [AuClPPh3] and 0.310 g (1.54 mmol) of K(iPrAT)
at room temperature. The solution was stirred for 32 h, the solvent
was removed in vacuo, and the remaining residue was extracted
with 50 mL of toluene. The extract was reduced to dryness, and a
yellow light-sensitive powder was obtained. Yield: 799 mg (88%).
1
Mp: 135-136 °C (dec). H NMR (THF-d8, 400 MHz, RT): δ )
3JH,H ) 8.9 Hz), 6.23 (d, 2 H, JH,H ) 11.2 Hz), 6.77 (dd, 2 H,
3
3
1.41 (d, 6 H, NCH(CH3)2, JH,H ) 6.2 Hz), 4.23 (sept, 1 H,
3JH,H ) 11.2 Hz, 8.9 Hz), 7.39-7.49 (m, 9 H, 9 CHPh o/p), 7.58-
7.67 (m, 6 H, 6 CHPh m). 13C{1H} NMR (THF-d8, 110.4 MHz,
RT): δ ) 25.4 (2 NCH(CH3)2), 49.7 (2 NCH(CH3)2), 109.1 (C5),
113.7 (C3,7), 129.4 (d, CHPh m, 3JC,P ) 10.3 Hz), 131.4 (d, CHPh p,
3
3
NCH(CH3)2, JH,H ) 6.2 Hz), 6.16 (dd, 1 H, JH,H ) 9.3 Hz, 9.3
3
3
Hz), 6.54 (d, 1 H, JH,H ) 11.2 Hz), 6.78 (d, 1 H, JH,H ) 11.2
Hz), 6.91 (ddd, 1 H, JH,H ) 11.2 Hz, 9.3 Hz, JH,H ) 1.5 Hz),
3
4
3
4
7.00 (ddd, 1 H, JH,H ) 11.2 Hz, 9.3 Hz, JH,H ) 1.5 Hz), 7.42-
7.52 (m, 9 H, 9 CHPh o/p), 7.63-7.74 (m, 6 H, 6 CHPh m). 13C-
{1H} NMR (THF-d8, 110.4 MHz, RT): δ ) 26.1 (NCH(CH3)2),
4JC,P ) 4.1 Hz), 133.1, 134.8 (d, CHPh o, JC,P ) 13.2 Hz), 161.9
2
(C1,2). The ipso C of the PPh3 group could not clearly be located.
31P{1H} NMR (THF-d8, 161.7 MHz, RT): δ ) 34.8. MS (80 eV,
EI, 30 °C): m/z (%) ) 662.1 (0.4) [M]+, 618.7 (2.1) [M - iPr],
50.6 (NCH(CH3)2), 112.6, 117.8, 124.3, 129.7 (d, CHPh m, 3JC,P
)
4
11.6 Hz), 131.9 (d, CHPh p, JC,P ) 2.1 Hz), 132.6 (d, CHPh i,
1JC,P ) 58.7 Hz), 134.6, 134.7, 135.1 (d, CHPh o, 2JC,P ) 14.0 Hz),
165.3 (C2), 179.7 (C1). 31P{1H} NMR (THF-d8, 161.7 MHz, RT):
δ ) 33.2. MS (80 eV, EI, 30 °C): m/z (%) ) 621.1 (50) [M]+,
459.4 (71) [M - iPrAT]+, 262.3 (100) [PPh3]+. Anal. Calcd for
C28H27AuNOP (Mr ) 621.46): C, 54.11; H, 4.38; N, 2.25. Found:
C, 54.00; H, 4.29; N, 1.98.
(40) Dochnahl, M.; Pissarek, J.-W.; Blechert, S.; Lo¨hnwitz, K.; Roesky,
P. W. Chem. Commun. 2006, 3405-3407.
(41) Dehnen, S.; Bu¨rgstein, M. R.; Roesky, P. W. Dalton Trans. 1998,
2425-2430.
(42) Roesky, P. W. Chem. Ber./Recueil 1997, 130, 859-862.
(43) Brauer, G. Handbook of PreparatiVe Inorganic Chemistry; Drei Ba¨nde,
Ferdinand Enke Verlag: Stuttgart, Germany, 1981.
Inorganic Chemistry, Vol. 46, No. 11, 2007 4601

Meiners et al.
Scheme 3
Table 1. Crystallographic Details of [Au{(iPr)2ATI}PPh3] (1) and
[Au{(Cy)2ATI}PPh3] (2)a
param
formula
1
2
C31H34AuN2P
662.54
C37H42AuN2P
742.66
fw
space group (No.)
a, Å
b, Å
P21/c (14)
14.3624(7)
10.3495(4)
19.4897(9)
P1h (2)
11.1572(8)
13.0802(10)
13.3000(10)
109.540(6)
110.119(6)
101.708(6)
1602.9(3)
2
c, Å
the final cycles of each refinement, all non-hydrogen atoms except
the disordered atoms C12 and C13 in 1 were assigned anisotropic
temperature factors. Carbon-bound hydrogen atom positions were
calculated and allowed to ride on the carbon to which they are
bonded assuming a C-H bond length of 0.95 Å. The hydrogen
atom contributions were calculated but not refined. The final values
of refinement parameters are given in Table 1. The locations of
the largest peaks in the final difference Fourier map calculation as
well as the magnitude of the residual electron densities in each
case were of no chemical significance. Positional parameters,
hydrogen atom parameters, thermal parameters, and bond distances
and angles have been deposited as Supporting Information. Crystal-
lographic data (excluding structure factors) for the structures
reported in this paper have been deposited with the Cambridge
Crystallographic Data Centre as a supplementary publication Nos.
CCDC 641196 (1) and 641197 (2). Copies of the data can be
obtained free of charge on application to CCDC, 12 Union Road,
Cambridge CB21EZ, U.K. (fax, (+(44)1223-336-033; email,
deposit@ccdc.cam.ac.uk).
R, deg
â, deg
106.771(4)
γ, deg
V, Å3
2773.8(2)
4
Z
density, g/cm3
radiatn (λ, Å)
µ, mm-1
abs corr
reflcns collcd
unique reflcns
obsd reflcns
GOF on F2
R1,b wR2c
1.587
Mo KR (0.710 73)
5.383
integration
35 534
7466 (Rint ) 0.0652)
5872
1.539
Mo KR (0.710 73)
4.667
integration
11 137
5600 (Rint ) 0.0597)
4570
1.023
0.0329, 0.0780
1.032
0.0422, 0.0831
a All data collected at 200 K. b R1 ) ∑||Fo| - |Fc||/∑|Fo|. c wR2 )
2
2
2
{∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2
.
[Au(CyAT)PPh3] (4). Under exclusion of light and under
stirring, 20 mL of THF was dropped into a mixture of 0.412 g
(0.833 mmol) of [AuClPPh3] and 0.250 g (1.04 mmol) of K(CyAT)
at room temperature. The mixture was stirred for 18 h, the solvent
was removed in vacuo, and the remaining residue was extracted
with 10 mL of toluene after stirring for 1 h. The extract was reduced
to dryness, and a yellow light-sensitive powder was obtained.
Yield: 0.510 g (93%). Mp: 125 °C (dec). 1H NMR (THF-d8, 400
MHz, RT): δ ) 1.08-1.20 (m, 1 H), 1.39-1.52 (m, 2 H), 1.62-
1.81 (m, 3 H), 1.81-1.93 (m, 2 H), 1.94-2.04 (m, 2 H), 3.85 (tt,
1 H, NCHCy, 3JH,H ) 10.7 Hz, 3.9 Hz), 6.17 (dd, 1 H, 3JH,H ) 8.9
Results and Discussion
Potassium N-isopropyl-2-(isopropylamino)troponiminate,
K{(iPr)2ATI}, and N-cyclohexyl-2-(cyclohexylamino)tropon-
imine, K{(Cy)2ATI}, were synthesized by treatment of the
neutral ligand with an excess of KH in THF (Scheme 3).
Whereas K{(iPr)2ATI} was described earlier by us,42
K{(Cy)2ATI} is a new compound, which was characterized
by 1H and 13C NMR spectroscopy. The spectra indicate that
the alkali metal cation of K{(Cy)2ATI} is not coordinated
by THF. As it has been observed previously for K{-
(iPr)2ATI}, the room-temperature NMR spectrum is indica-
tive of a very symmetrical structure. Transmetalation of
K{(iPr)2ATI} and K{(Cy)2ATI} with [AuClPPh3] in a 1:1
ratio followed by extraction with toluene afforded the
corresponding gold complexes [Au{(iPr)2ATI}PPh3] (1) and
[Au{(Cy)2ATI}PPh3] (2), respectively, as yellow powders
in good yields (Scheme 3). Both compounds can be shortly
handled in air, but they are light sensitive. The new
complexes have been characterized by standard analytical/
spectroscopic techniques, and the solid-state structures were
established by single-crystal X-ray diffraction.
The room-temperature 1H and 13C NMR spectra of
compounds 1 and 2 point to a symmetric coordination of
the aminotroponiminate ligand in solution, which is in
contrast to the asymmetric coordination observed in the solid
state (see below). Thus, the ligand may show fluctional
behavior in solution. The signal of the isopropyl CH of 1 is
well-resolved into a septet but shows a marked downfield
shift (δ ) 4.17 ppm) compared to the potassium salt (δ )
3
3
Hz, 8.9 Hz), 6.55 (d, 1 H, JH,H ) 11.5 Hz), 6.76 (d, 1 H, JH,H
)
3
11.2 Hz), 6.90 (dd, 1 H, C6H, JH,H ) 11.2 Hz, 8.9 Hz), 6.98 (dd,
3
1 H, JH,H ) 11.5 Hz, 8.9 Hz), 7.43-7.53 (m, 9 H, 9 CHPh o/p),
7.66-7.77 (m, 6 H, 6 CHPh m). 13C{1H} NMR (THF-d8, 110.4
MHz, RT): δ ) 26.7, 27.1, 37.7 (NCHCH2(Cy)), 59.8 (NCHCy),
112.6, 117.8, 124.2, 129.7 (d, CHPh m, 3JC,P ) 11.6 Hz), 131.9 (d,
CHPh p, 4JC,P ) 2.1 Hz), 132.7 (d, CHPh i, 1JC,P ) 59.5 Hz), 134.5,
134.6, 135.1 (d, CHPh o, JC,P ) 14.1 Hz), 165.2, 179.7. 31P{1H}
4
NMR (THF-d8, 161.7 MHz, RT): δ ) 33.9. MS (80 eV, EI, 30
°C): m/z (%) ) 661.3 (0.9) [M]+, 459.1 (3.8) [M - CyAT]+, 262.2
(49.6) [PPh3]+. Anal. Calcd for C31H31AuNOP (Mr ) 661.52): C,
56.28; H, 4.72; N, 2.12. Found: C, 56.02; H, 4.71; N, 2.00.
X-ray Crystallographic Studies of 1 and 2. Crystals of 1 were
grown by slow evaporation of toluene, and crystals of 2 were
obtained from toluene/pentane. Suitable crystals of both compounds
were covered in mineral oil (Aldrich) and mounted onto a glass
fiber. The crystals were transferred directly to the -73 °C cold N2
stream of a Stoe IPDS 2T diffractometer. Subsequent computations
were carried out on an Intel Pentium 4 PC.
All structures were solved by the Patterson method (SHELXS-
9744). The remaining non-hydrogen atoms were located from
successive difference Fourier map calculations. The refinements
were carried out by using full-matrix least-squares techniques on
F, minimizing the function (Fo - Fc)2, where the weight is defined
2
2
as 4Fo /2(Fo ) and Fo and Fc are the observed and calculated
structure factor amplitudes using the program SHELXL-97.45 In
(44) Sheldrick, G. M. SHELXS-97, Program of Crystal Structure Solution;
(45) Sheldrick, G. M. SHELXL-97, Program of Crystal Structure Refine-
ment; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
University of Go¨ttingen: Go¨ttingen, Germany, 1997.
4602 Inorganic Chemistry, Vol. 46, No. 11, 2007

AuI Aminotroponiminate and Aminotroponate Complexes
Figure 2. Solid-state structure of 2 showing the atom-labeling scheme,
Figure 1. Solid-state structure of 1 showing the atom-labeling scheme,
omitting hydrogen atoms.
omitting hydrogen atoms. Hydrogen atoms are omitted for clarity.
Scheme 4
Table 2. Selected Bond Lengths (Å) and Angles (deg) of
[Au{(iPr)2ATI}PPh3] (1) and [Au{(Cy)2ATI}PPh3] (2)
param
1
2
Bond Lengths (Å)
2.178(3)
Au-N1
Au-N2
Au-P
2.188(6)
2.237(5)
2.204(2)
2.262(3)
2.2036(10)
Bond Angles (deg)
71.79(13)
2.188(6) Å and Au-N2 2.237(5) Å), and thus, the distortion
of the trigonal planar setup is less significant, resulting in
N-Au-P bond angles of 147.9(2) and 139.90(15)°. Again,
the ligand atoms N1, N2, and P as well as the gold atom are
in plane. As described above, no intermolecular Au(I)-
Au(I) contacts are observed in the solid state.
N1-Au-N2
N1-Au-P
N2-Au-P
72.2(2)
147.9(2)
139.90(15)
151.10(9)
137.11(10)
3.67 ppm). As expected, the alkyl resonances of the
cyclohexyl ring of compound 2 are not well resolved. In
contrast the signals of the seven-membered rings of com-
pounds 1 and 2 show the typical well-resolved pattern
expected for aminotroponiminate ligands. In the 31P{1H}
NMR spectra, both complexes show the expected signal for
the Ph3P phosphorus atoms at δ ) 34.8 ppm (1) and 34.2
(2) ppm, respectively, which are in the range of the starting
material [AuClPPh3].
The solid-state structures of compounds 1 and 2 were
investigated by single-crystal X-ray diffraction. Data col-
lection parameters and selected bond lengths and angles are
given in Tables 1 and 2, respectively. Compound 1 crystal-
lizes in the monoclinic space group P21/c having four
molecules in the unit cell (Figure 1). The gold atom in
compound 1 is distorted trigonal planar coordinated by the
PPh3 group and the two nitrogen atoms (N1 and N2) of the
aminotroponiminate ligand. The tendency of Au(I) to form
a linear setup results in an asymmetric attachment of the
{(iPr)2ATI}- ligand to the metal center. Thus, the Au-N1
bond length of 2.178(3) Å is significantly shorter than the
Au-N2 bond distance of 2.262(3) Å. As a result of this
distortion the N-Au-P angle differs by about 14° (N1-
Au-P 151.10(9)° and N2-Au-P 137.11(10)°). The ligand
atoms N1, N2, and P as well as the gold atom are in plane.
No intermolecular Au(I)-Au(I) contacts within 5.0 Å are
observed in the solid state.
To compare the reactivity and the coordination mode of
the aminotroponiminate ligand (D, Scheme 1) with a similar
bidentate ligand system, we also introduced aminotroponates
(E, Scheme 1) into Au(I) chemistry. In comparison to
aminotroponiminates, the imine group is formally replaced
by an oxo group in aminotroponates. Thus, both ligand
systems D and E are closely related. As transfer reagents
we again used potassium derivatives of the ligands. Whereas
potassium 2-(isopropylamino)troponate (K(iPrAT))41 was
described earlier, the corresponding cyclohexyl analogue
(K(CyAT)) was unknown. The latter compound was obtained
by deprotonation of (CyAT)H with KH in THF at room
temperature (Scheme 4). K(CyAT) is a air-sensitive yellow
1
powder, which was characterized by H and 13C NMR
spectroscopy. The spectra show the expected set of signals.
Reaction of K(iPrAT) and K(CyAT) with [AuClPPh3] in
THF resulted after extraction with toluene in the correspond-
ing gold complexes of composition [Au(iPrAT)PPh3] (3) and
[Au(CyAT)PPh3] (4) (Scheme 4). Complexes 3 and 4 were
characterized by MS, 1H, 13C{1H}, and 31P{1H} NMR
1
spectroscopy, and elemental analysis. The H and 13C{1H}
NMR spectra show the expected set signals for the (iPrAT)-
ligand. The signals of the isopropyl CH of 3 appear as a
well-resolved septet at δ ) 4.23 ppm, which is a significant
downfield shift compared to the starting material K(iPrAT)
(δ ) 3.61)41 As observed for compound 2 in complex 4, the
alkyl resonances of the cyclohexyl ring are not well resolved
but the signals of the seven membered rings of compounds
3 and 4 show the typical well-resolved pattern expected for
aminotroponate ligands. In the 31P{1H} NMR the signal for
Compound 2 crystallizes in the triclinic space group P1h
having two molecules in the unit cell (Figure 2). As already
observed for compound 1 the gold atom in compound 2 is a
distorted trigonal planar coordinated by the ligands. In
contrast to compound 1, the difference of the Au-N bond
distances of the {(Cy)2ATI}Au subunit is smaller (Au-N1
Inorganic Chemistry, Vol. 46, No. 11, 2007 4603

Meiners et al.
the PPh3 group is seen at δ ) 33.2 ppm (3) and 33.9 (2)
ppm, which is in the range of compounds 1 and 2. All the
analytical data obtained for complexes 3 and 4 point toward
monomeric gold complexes although we cannot absolutely
exclude Au(I)-Au(I) contacts in the solid state. Single
crystals of compounds 3 and 4 could not be obtained. So far
we can only speculate about the coordination number of the
gold atoms. In analogy to compounds 1 and 2, we suggest
that as a result of the rigid nature of the aminotroponate
ligand also the gold atoms in compounds 3 and 4 could be
three-coordinated. Compounds 1-4 do not show any emis-
sion by irradiation with an UV lamp. Photoluminescence
measurements of compounds 2 and 4 were performed at
room temperature. These measurements show only a broad
photoluminescence with a low intensity.46
K(iPrAT) and K(CyAT) were obtained from the isopropyl-
and cyclohexyl-substituted aminotropones. Both amino-
troponates and aminotroponiminates are rigid bidentate
monoanionic ligand systems. Transmetalation of the potas-
sium compounds with [AuClPPh3] resulted in the gold
complexes [Au{(iPr)2ATI}PPh3], [Au{(Cy)2ATI}PPh3], [Au-
(iPrAT)PPh3], and [Au(CyAT)PPh3]. The solid-state struc-
tures of the aminotroponiminate complexes were investigated
by single-crystal X-ray diffraction. The gold atoms in both
compound are distorted trigonal planar coordinated by the
PPh3 group and the two nitrogen atoms of the aminotropon-
iminate ligand. The ligand atoms N1, N2, and P as well as
the gold atom are in plane. Thus, a new class of three-
coordinated gold(I) complexes was established, which to the
best of our knowledge are the first gold(I) complexes having
an N,N’-bidentate monoanionic ligand in the coordination
sphere.
Summary
In summary, we have synthesized the potassium com-
pounds K{(iPr)2ATI} and K{(Cy)2ATI} of the isopropyl-
and cyclohexyl-substituted aminotroponimines by deproto-
nation reaction. In a similar way the potassium derivatives
Acknowledgment. Umicore AG & Co. KG is acknowl-
edged for the donation of HAuCl4.
Supporting Information Available: X-ray crystallographic
files in CIF format for the structure determinations of 1 and 2.
This material is available free of charge via the Internet at
http://pubs.acs.org.
(46) 2: UV-vis-emission (λex ) 465 nm, OD465 ) 0.785) (nm): λem
570-830 (broad band, with the maximum of intensity at 620 nm). 4:
UV-vis-emission (λex ) 445 nm, OD445 ) 0.520) (nm): λem
455-695 (broad band, with the maximum of intensity at 535 nm).
)
)
IC0701662
4604 Inorganic Chemistry, Vol. 46, No. 11, 2007