Isolation of an intermediate during the decomposition of a tetragold-phosphane complex

Article abstract of DOI:10.1002/ejic.200400439

Reaction of the diphosphanylamine 2,6-{(Ph₂P)₂N} ₂C₅H₃N with four equivalents of Au(tht)C1 (tht = tetrahydrothiophene) affords the tetragold complex 2,6-{(ClAuPh ₂P)₂N}₂C₅H₃N in high yield. Decomposition of the tetragold compound results in the formation of the digold complex 2,6-{(ClAuPh₂P)HN}₂C₅H ₃N and colloidal gold. A trigold intermediate, which contains a Au-Au interaction [2.9886(5) A] has been isolated, and while ultimately unstable, it is thought to be partially stabilised by virtue of the aurophilic nature of gold. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejic.200400439

FULL PAPER
Isolation of an Intermediate during the Decomposition of a Tetragold-
Phosphane Complex
Nermin Biricik,[a] Zhaofu Fei,[a] Rosario Scopelliti,[a] and Paul J. Dyson*[a]
Keywords: N,P Ligands / Diphosphanylamines / Gold complexes
Reaction of the diphosphanylamine 2,6-{(Ph2P)2N}2C5H3N
with four equivalents of Au(tht)Cl (tht = tetrahydrothi-
trigold intermediate, which contains a Au−Au interaction
[2.9886(5) A] has been isolated, and while ultimately un-
˚
ophene)
affords
the
tetragold
complex
2,6-
stable, it is thought to be partially stabilised by virtue of the
aurophilic nature of gold.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
{(ClAuPh2P)2N}2C5H3N in high yield. Decomposition of the
tetragold compound results in the formation of the digold
complex 2,6-{(ClAuPh2P)HN}2C5H3N and colloidal gold. A
Introduction
of colloidal gold particles. Formation of gold colloids, typi-
cally denoted by the precipitation of a purple/black powder,
Gold()-phosphane complexes and clusters have been ex- is frequently observed in gold() chemistry, however, the in-
tensively studied over the years.[1] Apart from fundamental termediate species formed during the decomposition pro-
interest in these types of compounds, they exhibit a number cess and decomposition mechanism remain essentially un-
of interesting properties which gives rise to a wide range of known. In this paper we describe the synthesis of a tetra-
different applications. Gold() complexes display anticancer gold-diphosphanylamine complex and its decomposition to
activity and are employed in clinics for the treatment of a digold species in which an intermediate trigold compound
rheumatoid arthritis.[2] In addition, they exhibit interesting is isolated and characterised, providing insight into the de-
photophysical[3] and catalytic properties.[4] From the pleth- composition mechanism.
ora of studies involving gold() complexes, interactions be-
tween linearly coordinated gold() centres have been found
to be extremely common, leading to self-assembled supras-
Results and Discussion
tructures through AuϪAu intermolecular contacts.[5] In
many cases these suprastructures exhibit strong photo-lumi-
nescence.[6] The term used to describe the affinity of gold
to form AuϪAu interactions is ‘‘aurophilicity’’,[7] which was
introduced in 1989, and theoretical studies have since
placed the effect on a solid foundation.[8]
The diphosphanylamine ligand 2,6-{(Ph2P)2N}2C5H3N
(L1) has previously been shown to undergo a remarkable
reaction with Hϩ to form the iminobiphosphane 2,6-
(Ph2PϪPh2PϭN)2C5H3NHϩ.[14] Since Hϩ and certain gold
fragments are isolobal[15] we thought that it would be
interesting to explore the reactivity of L1 towards gold.
Thus, under an inert atmosphere, L1 was treated with four
equivalents of Au(tht)Cl (tht ϭ tetrahydrothiophene)
in dichloromethane at room temperature yielding 2,6-
{(ClAuPh2P)2N}2C5H3N (1) as the only product
(Scheme 1). The 31P NMR spectrum of the reaction solu-
tion exhibits a sharp singlet at δ ϭ 84.0 ppm indicating that
all of the phosphorus atoms are equivalent. In addition, the
electrospray ionisation mass spectrum of 1 in dichlorometh-
ane exhibits a parent peak at m/z ϭ 1775 which corresponds
to the protonated intact parent ion [M ϩ H]ϩ. After re-
moval of the solvent under reduced pressure 1 was obtained
as a white powder.
Many different phosphane ligands have been used to
form complexes with gold, in particular heterodentate
phosphanes, which tend to afford multi-nuclear complexes
containing AuϪAu interactions.[9] Such interactions have
been shown to persist in solution.[10] Aurophilicity is es-
pecially favoured where several phosphorus centres are in
close proximity, enabling intramolecular auration, for ex-
ample, in calix[3]arene and calix[4]arene based phosphane
systems.[11] Complexes with diphosphanylamine ligands are
also known.[12] Diphosphanylamines comprise a PϪNϪP
backbone and some of their gold() complexes are light/
moisture sensitive,[13] presumably due to the instability of
both the PϪN and AuϪP bonds, resulting in the formation
Compound 1 is stable in the solid state, but decomposes
slowly in solution on exposure to air/moisture. The de-
composition reaction can be monitored by 31P NMR spec-
troscopy. The 31P NMR spectrum in dichloromethane exhi-
[a]
´
Institut des Sciences et Ingenierie Chimiques, Ecole
´ ´
Polytechnique Federale de Lausanne, EPFL-BCH,
1015 Lausanne, Switzerland
E-mail: paul.dyson@epfl.ch
4232
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200400439
Eur. J. Inorg. Chem. 2004, 4232Ϫ4236

Decomposition of a Tetragold-Phosphane Complex
FULL PAPER
complex 2, which by virtue of being a salt, precipitates from
solution, on addition of diethyl ether. After filtration and
removal of the solvent, the solid was washed with diethyl
ether and obtained in its pure form and recrystallised from
chloroform to afford crystals suitable for analysis by X-ray
diffraction. The structure of the dication in 2 is shown in
Figure 1 and key bond parameters are listed in the caption.
Crystal data and details of the structure determination are
listed in Table 1 and further details are given in the Exper-
imental Section.
Compound 2 contains three gold centres and two differ-
ent ligands, 2-{(Ph2P)2N}-6-{(Ph2P)HN}-C5H3N (L2) and
2,6-{(Ph2P)HN}2C5H3N (L3) (see Figure 2), both derived
from the diphosphanylamine ligand L1 by substitution of
one and two Ph2P units by a proton, respectively. The
AuϪP and AuϪCl distances in 2 are similar to those ob-
served in structurally related compounds;[17] whereas the
˚
AuϪAu distance is 2.9886(5) A, which is somewhat longer
Scheme 1. Degradation of 1 and its decomposition to 3 via 2,
following exposure to air/light
than those usually found in complexes containing AuϪAu
bonds within an ‘‘A’’-frame structure involving a five-mem-
bits, in the first instance, the signal at δ ϭ 84.0 ppm corre- bered ring.[18] However, this distance is not long when com-
sponding to 1, which decreases in intensity until it has com- pared to those observed in complexes where the gold
pletely disappeared after six hours. In its place three broad centres are not orientated in such close proximity. The
˚
˚
signals at 97.0, 68.9, 52.2 ppm (for which the PϪP coupling Au(1)ϪP(1) [2.301(2) A], Au(1)ϪP(3) [2.312(2) A],
˚
˚
could not be resolved) together with signals at δ ϭ 35.6 ppm Au(2)ϪP(2) [2.303(2) A] and Au(2)ϪP(4) [2.299(2) A] dis-
and Ϫ20.6 ppm (JP-P ϭ 229.0 Hz) which are readily attri- tances are all similar, being slightly longer than the
buted to Ph2P(O)PPh2,[16] are observed. Simultaneously, the Au(3)ϪP(5) [2.219(3) A] distance which involves the
˚
reaction mixture turns from colourless to purple, a charac- PϪAuϪCl system. While the P(5)ϪAu(3)ϪCl(1) fragment
teristic colloid colouration, due to the formation of elemen- is nearly linear with an angle of 177.33(9)°, the
tal gold. The three unidentified signals correspond to a new P(1)ϪAu(1)ϪP(3) and P(2)ϪAu(2)ϪP(4) units form angles
Figure 1. Molecular structure of 2 in the solid state (ball-and-stick representation showing just the cation with a partial labelling scheme,
˚
the Cl anions and all the solvent molecules have been omitted for clarity); key bond lengths (A) and angles (°) include: Au(1)ϪP(1)
2.301(2), Au(1)ϪP(3) 2.312(2), Au(1)ϪAu(2) 2.9886(5), Au(2)ϪP(4) 2.299(2), Au(2)ϪP(2) 2.303(2), Au(3)ϪP(5) 2.219(3), Au(3)ϪCl(1)
2.305(3), P(1)ϪN(1) 1.670(7), P(2)ϪN(3) 1.673(8), P(3)ϪN(4) 1.694(7), P(4)ϪN(4) 1.702(8), P(5)ϪN(6) 1.676(8), P(1)ϪAu(1)ϪP(3)
163.94(8), P(1)ϪAu(1)ϪAu(2) 112.58(6), P(3)ϪAu(1)ϪAu(2) 80.68(6), P(4)ϪAu(2)ϪP(2) 174.23(8), P(4)ϪAu(2)ϪAu(1) 78.00(6),
P(2)ϪAu(2)ϪAu(1) 107.24(6), P(5)ϪAu(3)ϪCl(1) 177.33(9)
Eur. J. Inorg. Chem. 2004, 4232Ϫ4236
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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N. Biricik, Z. Fei, R. Scopelliti, P. J. Dyson
FULL PAPER
to 2 steadily disappear, with the concomitant formation of
a new singlet resonance at δ ϭ 55.1 ppm. The peak at δ ϭ
55.1 ppm has been assigned to 3, which has been isolated
in its pure form following the decomposition of 2 in di-
chloromethane on a preparative scale. In addition, 3 can be
prepared directly from the reaction of Au(tht)Cl with 2,6-
{(Ph2P)HN}2C5H3N (see below). The other components
from the reaction, as denoted by 31P NMR spectroscopy,
have been tentatively assigned as Ph2P(O)PPh2 (see above),
with lesser amounts of Ph2P(O)OH and Ph2POH, as rep-
resented by signals of low relative intensity at δ ϭ 35.5 and
24.0 ppm. A dark purple precipitate is observed which pre-
sumably corresponds to gold colloid. The structure of 3 has
been established in the solid-state by single-crystal X-ray
diffraction on crystals grown from a dichloromethane/di-
ethyl ether solution at room temperature. The molecular
structure of 3 is shown in Figure 3 and key bond param-
eters are listed in the caption.
Table 1. Crystal data and details of the structure determination for
2 and 3
2
3
Empirical formula
Molecular mass
Crystal system
Space group
C78H67Au3Cl27N6P5 C30.5H28Au2Cl5N3P2
2791.28
triclinic
P1
1069.68
triclinic
P1
¯
¯
˚
a (A)
15.8163(11)
16.2804(8)
22.6502(12)
83.714(4)
73.581(5)
65.340(6)
5084.1(5)
2
10.0883(7)
12.4008(9)
15.1675(10)
112.597(7)
95.294(5)
99.932(6)
1699.1(2)
2
˚
b (A)
˚
c (A)
a (°)
b (°)
g (°)
3
˚
V (A )
Z
Dcalcd. (g cmϪ3
F(000)
)
1.823
2.091
2696
5.150
1010
9.138
m (mmϪ1
)
Temp. (K)
Wavelength (A)
Measured reflections 29979
140(2)
0.71073
140(2)
0.71073
9959
˚
Unique reflections
Unique reflections
with I Ͼ 2σ(I)
Data/parameters
R[a] [I Ͼ 2σ(I)]
wR2[a] (all data)
GoF
15710
12810
5244
4698
15710/1075
0.0563
0.1602
5244/388
0.0280
0.0745
1.070
1.051
2 2
[a] R ϭ Σ| |Fo | Ϫ |Fc2| |/Σ|Fo 2|, 2wR2 ϭ {Σ[w(Fo2 Ϫ Fc2)2]/Σ[w(Fo ) ]}1/2
.
GoF ϭ {Σ[w(Fo Ϫ Fc ) ]/(n Ϫ p)}1/2 where n is the number of
[b]
data and p is the number of parameters refined.
Figure 2. Ligands L2 and L3
of 163.94(8) and 174.23(8)°, respectively. The deviation
Compound 3 is based on a L3-type ligand in which a
from linearity is presumably due to the bulky ligands sur- AuϪCl fragment coordinates to each phosphorus() cen-
rounding the AuϪAu unit, which also results in the rela- tre. The parameters in 3 are largely in accordance with the
tively long AuϪAu contact.
structurally similar compounds.[12,13] The Au(1)ϪP(1)
˚
˚
Compound 2 is stable in the solid-state, but decomposes [2.2377(14) A] and Au(2)ϪP(2) [2.2359(15) A] bond lengths
in solution on exposure to air/light. The decomposition re- are similar and somewhat longer than the related
˚
action of complex 2 in dichloromethane was followed in Au(3)ϪP(5) bond of 2.219(3)
A
in 2. The
situ by 31P NMR spectroscopy. The peaks corresponding P(1)ϪAu(1)ϪCl(1) and P(2)ϪAu(2)ϪCl(2) units are essen-
Figure 3. Molecular structure of 3 in the solid-state (ball-and-stick representation showing the labelling scheme, the solvent molecules
˚
have been omitted); key bond lengths (A) and angles (°) include: Au(1)ϪP(1) 2.2377(14), Au(1)ϪCl(1) 2.3229(13), Au(2)ϪP(2) 2.2359(15),
Au(2)ϪCl(2) 2.3063(14), P(1)ϪN(2) 1.698(5), P(2)ϪN(3) 1.710(5), P(1)ϪAu(1)ϪCl(1) 179.59(5), P(2)ϪAu(2)ϪCl(2) 178.69(6)
4234
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Decomposition of a Tetragold-Phosphane Complex
FULL PAPER
was removed under vacuum and the resulting white solid was
washed with diethyl ether (2 ϫ 2 mL) to give the product 1 as a
white powder. Yield: 330 mg, 94%. 1H NMR: δ ϭ 6.5Ϫ8.20 (m,
aromatic H) ppm. 31P NMR: δ ϭ 84.0 (s) ppm. ESI-MSϩ m/z: 1775
[M ϩ H]ϩ. C53H43Au4Cl4N3P4 (1775.52): H 2.44, C 35.85, N 2.37;
found H 2.47, C 35.89, N 2.34.
tially linear with bond angles of 179.59(5) and 178.69(6)°,
respectively.
The decomposition process 1 Ǟ 2 Ǟ 3 is worth some
further comment since 2 cannot be prepared by a rational
route. Complex 2 contains two different aminophosphane
ligands, L2 and 2,6-{(Ph2P)HN}2C5H3N (L3) which are de-
rived from L1 by substitution of one and two Ph2P units by
a proton, respectively. Ligand L3 has been reported be-
fore,[19] and attempts to prepare L2 using a rational route,
viz. reaction of one equivalent of 2,6-diaminopyridine with
three equivalents of Ph2PCl, are only partially successful.
The main product from this reaction is L1 based on 31P
NMR spectroscopy and electrospray ionisation mass spec-
trometry. The formation of L2 was identified in the reaction
mixture by electrospray ionisation mass spectrometry which
contained peaks corresponding to L1 and L2, the peak at
m/z ϭ 662 corresponds to [L2ϩH]ϩ, but it has, as yet, not
been possible to isolate L2 from the mixture, although at-
tempts are ongoing.
Reaction of L3 with Au(tht)Cl in a 1:2 molar ratio gave
complex 3 in quantitative yield, however, all attempts to
prepare 2 from different combinations of L1 and L3 and
Au(tht)Cl were unsuccessful. The reason that 2 is isolated
at all is probably due to the lower solubility of 2 relative to
1 and 3 since it is a salt which facilitates precipitation from
the reaction solution. However, this property alone does
not fully explain the stability of 2 and we propose that the
aurophilicity of gold, resulting in the AuϪAu interaction,
further stabilises the intermediate and facilitates its iso-
Synthesis of 2: A solution of 1 (300 mg, 0.17 mmol) in dichloro-
methane (10 mL) was stirred in air for 6 h at room temperature,
after which time the 31P NMR spectra showed the absence of the
starting material 1. The solvent was removed under reduced press-
ure and the remaining solid was washed with diethyl ether (3 ϫ 10
mL) to give 2 as a white powder. Colourless crystals were obtained
by slow evaporation of a solution in CDCl3 at room temperature.
Yield: 105 mg, 22%. M.p. 147 °C. 1H NMR: δ ϭ 6.5Ϫ8.20 (m,
aromatic H); 6.30 (broad signal, NH) ppm. 31P NMR: δ ϭ 97.0
(broad signal), 68.9 (broad signal), 52.2 (broad signal) ppm. ESI-
MSϩ m/z: 1765 [cation]ϩ. C70H59Au3Cl3N6P5 (1836.40): H 3.24, C
45.78, N 4.58; found H 3.31, C 45.89, N 4.60.
Synthesis of 3. Method A: A solution of 2 (190 mg, 0.10 mmol) in
dichloromethane (10 mL) was stirred in air in for 24 hours at room
temperature. The solvent was removed under reduced pressure and
the remaining solid was washed with diethyl ether (3 ϫ 10 mL).
Colourless crystals were obtained by slow evaporation of a solution
in dichloromethane at room temperature in two days. Yield:
40 mg, 41%.
Method B: Au(tht)Cl (64 mg, 0.20 mmol) was added to a solution
of L3 (47 mg, 0.10 mmol) in dichloromethane (10 mL) at 0 °C. The
reaction mixture was allowed to warm to room temperature and
stirred for 30 minutes. The solvent was removed under vacuum and
the resulting white solid was washed with diethyl ether (2 ϫ 2 mL)
lation. This property frequently results in structural diver- to give the product 3 as a white powder. Yield: 90 mg, 95%. M.p.
163 °C (decmp.). 1H NMR: δ ϭ 6.5Ϫ8.20 (m, aromatic H); 6.50
(br., NH) ppm. 31P NMR: δ ϭ 55.1 (s) ppm. ESI-MSϩ m/z: 942
[M ϩ H]ϩ. C29H25Au2Cl2N3P2 (942.32): H 2.67, C 36.96, N 4.46;
found H 2.71, C 37.04, N 4.39.
sity in gold() complexes.[20] However, we believe that com-
pound 2 is especially pleasing as all researchers preparing
novel gold complexes are frequently frustrated by decompo-
sition to (or formation of) gold colloids, and in our system,
we were fortunate enough to isolate a decomposition inter-
mediate.
X-ray Sructure Determination: Details about the crystals and their
structure refinement are listed in Table 1, whereas relevant geo-
metrical parameters, including bond lengths and angles are in-
cluded in the figure captions. Data collections for both compounds
were performed at 140 K on a 4-circle goniometer having kappa
geometry and equipped with an Oxford Diffraction KM4 Sapphire
CCD. Data reduction was carried out with CrysAlis RED, release
1.7.0.[24] Absorption corrections[25] have been applied to both data
sets. Structure solution and refinement as well as molecular graph-
ics and geometrical calculations were performed for both structures
with the SHELXTL software package, release 5.1.[26] The struc-
tures were refined using the full-matrix least-squares on F2 with all
of the non-H atoms defined anisotropically. H atoms were placed
in calculated positions using the ‘‘riding model’’.
Experimental Section
The
ligands
2,6-{(Ph2P)2N}2C5H3N
(L1)[21]
and
2,6-
{(Ph2P)HN}2C5H3N (L3)[19] and the complex Au(tht)Cl (tht ϭ
tetrahydrothiophene)[22] were prepared according to literature
methods. Solvents were dried using appropriate reagents and dis-
tilled prior to use. NMR spectra were recorded in CDCl3 at 20 °C
with a Bruker DMX 200 instrument using SiMe4 as the external
standard for the 1H NMR spectroscopy and 85% H3PO4 for the
31P NMR spectroscopy. ESI-MS spectra were recorded on a Ther-
moFinnigan LCQԹ Deca XP Plus quadrupole ion trap instrument
using a literature method.[23] Samples were infused directly into the
source at 5 µL minϪ1 using a syringe pump. The spray voltage was
set at 5 kV and the capillary temperature at 50 °C. The MS detector
was tuned automatically on the base peak, which optimised the
remaining parameters. Elemental analyses was carried out at the
Institute of Molecular and Biological Chemistry at the EPFL.
CCDC-242559 (for 2) and -242560 (for 3) contain the supplemen-
tary crystallographic data for this paper. These data can be ob-
tained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html
[or from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; Fax: ϩ44-1223-336-033; E-mail:
deposit@ccdc.cam.ac.uk].
Synthesis of 1: Au(tht)Cl (256 mg, 0.80 mmol) was added to a solu-
tion of 2,6-{(Ph2P)2N}2C5H3N (170 mg, 0.20 mmol) in dichloro-
Acknowledgments
methane (10 mL) at 0 °C. The reaction mixture was allowed to We thank the Swiss National Science Foundation and the EPFL
warm to room temperature and stirred for 15 minutes. The solvent for financial support.
Eur. J. Inorg. Chem. 2004, 4232Ϫ4236
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4235

N. Biricik, Z. Fei, R. Scopelliti, P. J. Dyson
FULL PAPER
T. Kaukorat, P. G. Jones, R. Schmutzler, Chem. Ber. 1994,
127, 1579.
[1]
For an excellent overview covering all aspects of gold chemistry
see, Gold: Progress in Chemistry, Biochemistry and Technology
[13] [13a]
M. M. Taqui Khan, E. Rama Rao, Polyhedron 1987, 6,
(Ed.: H. Schmidbaur), John Wiley & Sons, Chichester, 1999.
[13b]
1727.
A. Bauer, W. Mitzel, A. Schier, D. W. H. Rankin,
[2] [2a]
[2b]
M. C. Gimeno, A. Laguna, Chem. Rev. 1997, 97, 511.
C. F. Shaw III, Chem. Rev. 1999, 99, 2589.
[13c]
H. Schmidbaur, Chem. Ber./Recueil 1997, 130 323.
D.
Walther, T. Döhler, K. Heubach, O. Klobes, B. Schweder, H.
Görls, Z. Anorg. Allg. Chem. 1999, 625, 923.
Z. Fei, N. Biricik, D. Zhao, R. Scopelliti, P. J. Dyson, Inorg.
Chem. 2004, 43, 2228.
D. G. Evans, D. M. P. Mingos, J. Organomet. Chem. 1982,
232, 171.
[3]
V. W. W. Yam, K. K.-W. Lo, K. M.-C. Wong, J. Organomet.
Chem. 1999, 578, 3.
[14]
[15]
[16]
[4] [4a]
[4b]
D. Thompson, Gold Bull. 1999, 32, 12.
J. H. Teles, S.
Brode, M. Chabanas, Angew. Chem. Int. Ed. 1998, 37, 1415. [4c]
E. Mizushima, K. Sato, T. Hayashi, M. Tanaka, Angew. Chem.
Int. Ed. 2002, 41, 4563.
S. Berger, S. Braun, H.-O. Kalinowski, NMR-Spektroskopie von
Nichtmetallen, vol. 3, 31P NMR-Spektroskopie, Georg Thieme
Verlag, Stuttgart, New York, 1993.
[5]
[5a]
For some recent examples see:
C. Hollatz, A. Schier, H.
Schmidbaur, J. Am. Chem. Soc. 1997, 119, 8115. [5b] J. D. E. T.
Wilton-Ely, A. Schier, N. W. Mitzel, S. Nogai, H. Schmidbaur,
J. Organomet. Chem. 2002, 643, 313.
Jennings, R. J. Puddephatt, Inorg. Chem. 2002, 41, 4590.
[17] [17a] R. Uson, A. Laguna, M. Laguna, M. N. Fraile, P. G. Jones,
[5c]
W. J. Hunks, M. C.
[17b]
G. M. Sheldrick, J. Chem. Soc., Dalton Trans. 1986, 291.
A. M. Z. Slawin, M. B. Smith, J. D. Woollins, Polyhedron 1999,
[6] [6a]
C.-M. Che, H.-L. Kwong, V. W.-W. Yam, K.-C. Cho, J.
[17c]
´
P. A. Bella, O. Crespo, E. J. Fernandez, A.
18, 1135.
[6b]
Chem. Soc., Chem. Commun. 1989, 885.
C. King, J. C.
´
Fischer, P. G. Jones, A. Laguna, J. M. Lopez-de-Luzuriagaa,
Wang, M. N. I. Khan, J. P. Fackler Jr., Inorg. Chem. 1989, 28,
[17d]
M. Mongea, J. Chem. Soc., Dalton Trans. 1999, 4009.
Q.
[6c]
2145.
V. W.-W. Yam, E. C.-C. Chen, Z.-Y. Zhao, Angew.
Zhang, G. Hua, P. Bhattacharyya, A. M. Z. Slawin, J. D. Wool-
[6d]
Chem. Int. Ed. 2000, 39, 1683.
C. D. Delfs, H. J. Kitto, R.
lins, Dalton Trans. 2003, 3250.
Stranger, G. F. Swiegers, S. B. Wild, A. C. Willis, G. J. Wilson,
Inorg. Chem. 2003, 42, 4469.
[18] [18a]
P. Schwerdtfeger, H. L. Hermann, H. Schmidbaur, Inorg.
[18b]
Chem. 2003, 42, 1334.
M. D. Irwin, H. E. Abdou, A. A.
[7]
[8]
[7a] P. G. Jones, Gold Bull. 1981, 14, 102. [7b] S. S. Pathaneni, G.
R. Desiraju, J. Chem. Soc., Dalton Trans. 1993, 319.
H. Schmidbaur, Gold Bull. 2000, 33, 3.
Mohamed, J. P. Fackler Jr., Chem. Commun. 2003, 2882.
[19] [19a]
W. Schirmer, U. Floerke, H. J. Haupt, Z. Anorg. Allg.
Chem. 1987, 545, 83. [19b] W. Schirmer, U. Floerke, H. J. Haupt,
Z. Anorg. Allg. Chem. 1989, 574, 239.
[9] [9a]
H. Schmidbaur, C. Paschalidis, O. Steigelmann, G. Müller,
Chem. Ber. 1989, 122, 1851. [9b] D. S. Eggleston, J. V. McArdle,
[20] [20a]
[20b]
J. P. Fackler Jr., Inorg. Chem. 2002, 41, 6959.
J. D. E.
[9c]
G. E. Zuber, J. Chem. Soc., Dalton Trans. 1987, 677.
P.
T. Wilton-Ely, A. Schier, N. W. Mitzel, H. Schmidbaur, J.
Chem. Soc., Dalton Trans. 2001, 1058.
[20c]
Sakhaii, I. Neda, M. Freytag, H. Thönnessen, P. G. Jones, R.
Schmutzler, Z. Anorg. Allg. Chem. 2000, 626, 1246.
J. Zank, A. Schier, H. Schmidbaur, J. Chem. Soc., Dalton Trans.
1998, 323.
J. D. E. T. Wilton-
Ely, A. Schier, H. Schmidbaur, Organometallics 2001, 20, 1895.
N. Biricik, Z. Fei, R. Scopelliti, P. J. Dyson, Helv. Chim. Acta
2003, 86, 3281.
R. Uson, A. Laguna, M. Laguna, Inorg. Synth. 1989, 26, 85.
P. J. Dyson, J. S. McIndoe, Inorg. Chim. Acta 2003, 354, 68.
Oxford Diffraction Ltd., Abingdon, Oxfordshire, UK, 2003.
DELABS, N. Walker, D. Stuart, Acta Crystallogr., Sect. A
1983, 39, 158.
[10]
[21]
[11] [11a]
[22]
[23]
[24]
[25]
C. B. Dieleman, D. Matt, I. Neda, R. Schmutzler, A. Har-
[11b]
riman, R. Yaftian, Chem. Commun. 1999, 1911.
C. B. Di-
eleman, D. Matt, I. Neda, R. Schmutzler, H. Thönnessen, P. G.
Jones, A. Harriman, J. Chem. Soc., Dalton Trans. 1998, 2115.
[12] [12a]
V. W.-W. Yam, C.-L. Chan, K.-K. Cheung, J. Chem. Soc.,
[12b]
[26]
Dalton Trans. 1996, 4019.
baur, Z. Naturforsch., Teil B 1997, 52, 769.
Grieve, R. J. Haines, N. May, M. M. Zulu, Polyhedron 1998,
P. Lange, A. Schier, H. Schmid-
G. M. Sheldrick, University of Göttingen, Germany, 1997;
Bruker AXS, Inc., Madison, Wisconsin, 53719, USA, 1997.
Received May 26, 2004
[12c]
J. S. Field, J.
[12d]
17, 3021.
A. M. Z. Slawin, M. B. Smith, J. D. Woollins, J.
Early View Article
Published Online September 7, 2004
Chem. Soc., Dalton Trans. 1998, 1537. [12e] I. Neda, A. Fischer,
4236
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