Aurophilic towards H-bonding interactions in phosphine-pyrazolato-gold(I) complexes: Luminescence studies and crystal structure of {3,5-bis-[4-(octyloxy) phenyl]-1H-pyrazolato-κN1}(triphenylphosphine)gold-{3,5-bis-[4- (octyloxy)phenyl]-1H-pyrazole} ([Au(pzop2)(PPh3)] ·(Hpzop2))

Article abstract of DOI:10.1002/hlca.200490184

Compounds [{Au(pz^R2)(PPh₃)₂} ] (pz ^R2 = 3,5-disubstituted pyrazolato; R = BuOC₆H₄ (bp), 1; R = C₈H₁₇OC₆H₄ (op), 2; R = C₆H₁₃OC₆H₄ (hp), 3) were easily obtained by reaction of [Au(NO₃)(PPh₃)] and the corresponding pyrazolato ligand. They exhibit similar NMR patterns, their ESI-MS or FAB-MS data being in agreement with a monomeric molecular formulation [Au(pz^R2)(PPh₃)]. By contrast, 1 crystallizes as the dimer [{Au(pz^R2}(PPh₃)}₂] and exhibits aurophilic Au ... Au contacts, while crystallization of 2 in CH₂Cl ₂/ hexane gives rise to compound 4, [Au(pz^op2)(PPh ₃)] · (Hpz^op2). The X-ray structure of 4 was solved, showing a H-bond interaction between the monomer of 2 and Hpz ^op2. Reactions between [{Au(pz^R2)(PPh₃)} ₂] and their corresponding 1H-pyrazole (Hpz^R2) were also explored. Compounds 1-3 exhibit luminescence in the solid state. Their emission spectra are reported and analyzed.

Full text of DOI:10.1002/hlca.200490184

Helvetica Chimica Acta Vol. 87 (2004)
2057
Aurophilic towards H-Bonding Interactions in Phosphine-pyrazolato-gold(I)
Complexes: Luminescence Studies and Crystal Structure of {3,5-Bis-
[4-(octyloxy)phenyl]-1H-pyrazolato-kN1}(triphenylphosphine)goldÀ{3,5-Bis-
op2
[4-(octyloxy)phenyl]-1H-pyrazole} ([Au(pzop )(PPh3)] ¥ (Hpz ))
2
by Paloma Ovejeroa), Mercedes Cano*a), Jose¬ A. Campoa), Jose¬ V. Herasa), Antonio Lagunab), Olga
Crespob), Elena Pinillaa)c), and M. Rosario Torresc)
a
¬
) Departamento de QuÌmica Inorganica I, Facultad de Ciencias QuÌmicas, Universidad Complutense, E-28040
Madrid (e-mail: mmcano@quim.ucm.es)
b
¬
¬
) Departamento de QuÌmica Inorganica, Instituto de Ciencia de Materiales de Aragon, Universidad de
Zaragoza-CSIC, E-50009 Zaragoza
c
¬
) Laboratorio de Difraccion de Rayos-X, Facultad de Ciencias QuÌmicas, Universidad Complutense, E-28040
Madrid
Compounds [{Au(pzR )(PPh3)}2] (pzR ˆ 3,5-disubstituted pyrazolato; R ˆ BuOC6H4 (bp), 1; R ˆ
2
2
C8H17OC6H4 (op), 2; R ˆ C6H13OC6H4 (hp), 3) were easily obtained by reaction of [Au(NO3)(PPh3)] and
the corresponding pyrazolato ligand. They exhibit similar NMR patterns, their ESI-MS or FAB-MS data being
in agreement with a monomeric molecular formulation [Au(pzR )(PPh3)]. By contrast, 1 crystallizes as the
2
dimer [{Au(pzR )(PPh3)}2] and exhibits aurophilic Au ¥¥¥ Au contacts, while crystallization of 2 in CH2Cl2/
2
op2
hexane gives rise to compound 4, [Au(pzop )(PPh3)] ¥ (Hpz ). The X-ray structure of 4 was solved, showing a
2
H-bond interaction between the monomer of 2 and Hpzop . Reactions between [{Au(pz )(PPh3)}2] and their
R2
2
corresponding 1H-pyrazole (HpzR ) were also explored. Compounds 1 3 exhibit luminescence in the solid
2
state. Their emission spectra are reported and analyzed.
A recent topic of interest in the study of gold(I) complexes deals with the
contribution of new supramolecular structures associated with the presence of Au ¥¥¥
Au interactions. These contacts have been considered to be comparable to H-bonding
forces [1], being responsible for most of the structural features and architectures found
in gold(I) complexes [1b][2]. An additional interest derives from the luminescence
properties of such molecular materials, which, in several cases, have also been related to
the existence of Au ¥¥¥ Au contacts [1d][3].
In a previous work on gold(I) derivatives based on 3,5-disubstituted pyrazolato
ligands (pzR2), we found that [{Au(pzpb2)(PPh3)}2] (bp ˆ BuOC6H4; 1) exhibited a
dimeric molecular structure in the solid state with an Au ¥¥¥ Au distance of 3.029(1) ä,
characteristic of aurophilic interactions [4]. A similar molecular array was also
suggested for related compounds bearing longer alkyloxy chains, i.e., of eight or six C-
atoms ([{Au(pzop )(PPh3)}2] (op ˆ C8H17OC6H4, 2); [{Au(pzhp )(PPh3)}2] (hp ˆ
C6H13OC6H4; 3)) [4]. Complex 1 was luminescent in the solid state at 77 K [4]. We
now are interested in the knowledge of the luminescence properties of compound 1 in
solution where the aurophilic interactions could be absent, as well as in extending the
luminescence studies to the related compounds 2 and 3 containing longer substituent
2
2
¹ 2004 Verlag Helvetica Chimica Acta AG, Z¸rich

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Helvetica Chimica Acta Vol. 87 (2004)
chains at the pyrazol ring. The actual work is focused as an additional contribution to
the study of the aurophilic interactions/luminescence properties relationship.
On the other hand, it is also interesting to note that a new compound 4 was obtained
when we tried to grow crystals from the solid 2. It was identified by X-ray diffraction as
op2
the association compound [Au(pzop )(PPh3)] ¥ (Hpz ) (4). Compound 4 was also
2
prepared by direct synthesis from [{Au(pzop )(PPh3)}2] (2) and Hpz and characterized
op2
2
by analytical and spectroscopic techniques.
Synthetic and Structural Studies. Compounds 1 3 were synthesized and their IR,
1H- and 31P-NMR, and mass spectra studied (see Exper. Part). The IR spectra in the
1
solid state and the H-NMR spectra in CDCl3 solution confirm the presence of both
coordinated PPh3 and pyrazolato ligands, the NMR data indicating a 1:1 molar ratio
between them. The presence of two equivalent substituents of the coordinated
pyrazolato ligand is also deduced from the NMR spectra, which suggests a metal-
lotropic equilibrium [5]. The 31P-NMR spectra exhibit only one resonance (d(P) ca.
32.8), which appears in the region usually observed for PPh3 coordinated to a AuI atom
in related compounds: ([Au(imd)(PPh3)] (imd ˆ imidazolato), d(P) 32.4 [6];
[Au(1,2,4-triaz)(PPh3)] (triaz ˆ triazolato), d(P) 31.5 [7]; [Au(pz)(PPh3)] (pz ˆ pyr-
azolato), d(P) 31.7 [6]). The ESI-MS data provide direct evidence for the monomeric
form of 1 and 2, showing peaks at 823.6 and 935.6, respectively, associated with the
‡
‡
parent ion [M ‡ H] . The molecular ion M could be observed in the FAB-MS of 3. The
above data agree with a monomeric nature of the compounds 1 3 in solution, avoiding
therefore the presence of Au ¥¥¥ Au interactions. By contrast, the evidence for short
Au ¥¥¥ Au distances in the dimer 1, determined by its X-ray crystal structure [4],
suggests those associations to be characteristic of the solid state. In a recent paper, this
proposal has also been confirmed in related compounds containing the 3,5-diphenyl-
pyrazolato ligand [8]. Following those precedents, we tried to get adequate crystals of 2
to assess its structure. However, when a solid sample of 2 was left to crystallize from
CH2Cl2/hexane solutions, crystals of a new compound 4, characterized by its X-ray
op 2
structure as [Au(pzop )(PPh3)] ¥ (Hpz ), were isolated.
2
On this basis we thought that the addition of pyrazole (HpzR2) to the monomeric
[Au(pzR2)(PPh3)] derivatives could produce an association through H-bonds involving
a N-atom of the pyrazolato ligand and the NH group of the free pyrazole, which should
modify or avoid the aurophilic interactions. In fact, the reaction of 2 with equimolar
quantities of Hpzop gave rise to the expected product 4. Its IR spectrum in KBr discs
2
shows, in addition to other bands, a nÄ(NH) absorption at 3223 cmÀ1, which is consistent
with the presence of pyrazole. This band appears almost unmodified with respect to
that of the free ligand [9]. Because related pyrazoles have shown H-bonds in the solid
state [5b][10], the above result agrees with the presence of the H-bonding interaction
in 4. The pattern of its 1H-NMR spectrum consists of one HÀC(4) resonance and two
aromatic signals from protons of equivalent aryl substituents at the heterocycles. The
alkyl chains are also equivalent as deduced from their observed signals. The
relationship found between the PPh3 and HÀC(4) protons is 15 :2, in agreement with
1
the proposed formulation. The H-NMR results could be explained by considering a
rapid exchange between uncoordinated and coordinated pyrazole moieties, making
both to be equivalent on the NMR timescale. The 31P-NMR spectrum presents a unique

Helvetica Chimica Acta Vol. 87 (2004)
2059
resonance at d(P) 32.8in the region of a coordinated PPh 3 ligand [6][7]. The ESI-MS
‡
of 4 shows a peak at 1409.1 for the [M À H] ion, confirming the association pyrazole ¥
pyrazolato in the compound.
bp2
Looking for getting a related complex [Au(pzbp )(PPh3)] ¥ (Hpz ) containing
2
shorter chains as substituents, we carried out the reaction of 1 with its corresponding
pyrazole Hpzbp . However, in this case, only a mixture of the starting compounds could
2
be isolated, indicating that the expected reaction did not take place.
The above results are summarized in the Scheme. In 1, the Au ¥¥¥ Au interactions in
the solid state are favored towards the H-bonds found in 4. Then it could be suggested
that, for two-coordinate gold(I) complexes of the type [Au(pzR2)(PPh3)], the steric and
electronic consequences of the pyrazole group are responsible for the potentially
different intermolecular interactions in the solid.
Scheme
a) Crystallization process in CH2Cl2/hexane; R ˆ BuOC6H4. b) Crystallization process in CH2Cl2/hexane;
R ˆ C8H17OC6H4.
op2
Crystal Structure of [Au(pzop )(PPh3)] ¥ (Hpz ) (4). The molecular structure of 4
2
with the atom numbering scheme is depicted in Fig. 1. The compound crystallizes in the
≈
triclinic system, space group P1.
The molecule is composed of two entities, [Au(pzop )(PPh3)] and 1H-pyrazole,
linked by a strong H-bond with a N(3) ¥¥¥ N(2) distance of 2.941(5) ä and a
N(3)ÀH(3) ¥¥¥ N(2) angle of 172.2(2)8. Both entities are crossed as it is evidenced by
the dihedral angle between the heterocyclic planes of 65.5(2)8. It is remarkable to note
that the aryl substituents of the uncoordinated pyrazole are approximately parallel to
the own heterocyclic ring (5.3(1) and 10.1(1)8). However the coordinated pyrazolato
ligand shows one aryl substituent to be almost parallel (6.8(1)8) and the other twisted
(53.7(1)8) to its own heterocyclic plane.
2
The geometry around the Au-atom is, as expected, almost linear, the
P(1)ÀAu(1)ÀN(1) angle being 176.2(1)8. The Au(1)ÀN(1) and Au(1)ÀP(1) bond
lengths are 2.034(3) and 2.239(1) ä, respectively, similar to those found in related
complexes [4][6 8][11]. No intermolecular Au ¥¥¥ Au interactions were found, the

2060
Helvetica Chimica Acta Vol. 87 (2004)
Fig. 1. Perspective ORTEP plot of 4. H-Atoms, except H(3), and the labelling of some atoms are omitted for
clarity. The thermal ellipsoids are at 35% probability level. Selected bond lengths [ä] and angles [8]:
Au(1)ÀN(1) 2.034(3), Au(1)ÀP(1) 2.239(1), N(1)ÀN(2) 1.367(4), N(3)ÀN(4) 1.366(5), N(3)ÀH(3) 0.9988,
N(2) ¥¥¥ H(3) 1.95, N(2) ¥¥¥ N(3) 2.941(5), P(1)ÀAu(1)ÀN(1) 176.2(1), Au(1)ÀN(1)ÀN(2) 119.0(2),
N(3)ÀH(3) ¥¥¥ N(2) 172.2(2).
shortest distance being 6.50 ä. Further structural details are listed in the legend of
Fig. 1.
The molecular packing indicated a layer-like molecular distribution, by considering
two types of layers (A and B). Layer A (Fig. 2,a) is defined for the uncoordinated
pyrazole units, the lateral chains being bent ca. 1058 from the hypothetical O(3) ¥¥¥
C(61) line, which passes through the three planar rings. This folded layer lies almost
parallel to the (011) plane.
Layer B contains the [Au(pzop )(PPh3)] units, and it lies almost parallel to the
2
ac plane. This layer is formed by two sheets containing the Au(PPh3) groups in a head-
to-tail disposition. Weak CÀH ¥¥¥ O(N) contacts between the two sheets of a layer
(C(75) ¥¥¥ O(2) (x ‡ 1, y, z) 3.42 ä; C(81) ¥¥¥ N(2) (À x ‡ 1, À y ‡ 2, À z ‡ 1) 3.34 ä)
define a two-dimensional network (Fig. 2,b).
Both layers A and B are crossed with the chains of the uncoordinated pyrazole units
(A) occupying the free space between the sheets of the layer of [Au(pzR2)(PPh3)] (B)
(Fig. 2,c). This structural feature could be related to the molecular crossing observed in
the asymmetric unit.
Luminescence Properties. The emission spectra of compounds 1 3 were studied
both in the solid state and in acetone solution (Table 1). Only dimer 1 is slightly
luminescent at room temperature, although the emissions are weak (Fig. 3,a), and
none of them show emissions in acetone solution. At 77 K in the solid state, 1 3 are all
luminescent and display similar spectra consisting of a broad band in which three
maximum are found (Fig. 3,b). So, in all cases, the excitation at ca. 330 nm produces an
emission maximum located at ca. 450 nm (see Table 1 and Fig. 3). The pattern and
energies of the observed band resemble closely those recently reported by Fackler and
co-workers for a family of related pyrazolato-gold(I) complexes, the emissions being

Helvetica Chimica Acta Vol. 87 (2004)
2061
Fig. 2. a) View of layer A. b) View of layer B. c) Molecular packing of 4 showing the crossing of the two different
types of layers.

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Helvetica Chimica Acta Vol. 87 (2004)
Table 1. Emission and Excitation Maxima (l in nm) Measured for Complexes 1
3
a
Solid (298K)
Solid (77 K)
Solution (298K) )
lexc
lem
lexc
lem
b
1
2
3
321
421, 447
320
321
337
415, 445, 470
419, 446, 482
428, 446, 482
)
)
)
b
b
)
b
b
)
a) 5 Â 10À4 m in acetone. b) No emission observed.
assigned to ligand-to-metal charge-transfer processes [8]. On the other hand, it has
been observed for several gold(I) derivatives containing inter- or intramolecular Au ¥¥¥
Au contacts that emissions attributed to Au ¥¥¥ Au metal-centered transitions appear at
lower energies (lmax ca. 600 nm) than those above mentioned for our complexes [12].
On these bases, the emissions observed in 1 3 could be assigned to ligand-to-metal
charge-transfer processes. Despite this assignation and taking into account the non-
emissive nature in solution of our compounds, it could be suggested that the Au ¥¥¥ Au
interactions contribute to the observed emissions. However, the presence of such
interactions alone is not sufficient to produce luminescence properties, in agreement
with evidence previously established by Fackler and co-workers [8].
We are grateful to the DGI/McyT of Spain (Project No. BQU2003-07343) for financial support.
Experimental Part
General. The starting Au-complex [Au(NO3)(PPh3)] and the 3,5-bis[4-(alkyloxy)phenyl]-1H-pyrazoles
hp2
op2
(Hpzbp , Hpz , and Hpz ) were prepared by known procedures [9][10][13]. All commercial reagents were
used as supplied. Luminescence: Perkin-Elmer LS-50B luminescence spectrometer; emission and excitation
spectra were not corrected for instrumental response; solid-state samples were packed into capillary tubes and
introduced into the Perkin-Elmer variable-temp. accessory; solns. in acetone, 5 Â 10À4 m. IR Spectra: Nicolet
2
FTIR-Magna-550 spectrophotometer; KBr discs; 4000 350 cmÀ1 region; in cmÀ1 1H- and 31P{1H}-NMR
.
Spectra: Bruker DPX-300 (300.13 and 121.49 MHz for 1H and 31P, resp.) or Bruker AC-200 (200.13 MHz for 1H)
spectrophotometers; CDCl3 solns.; chemical shifts d(H) in ppm rel. to SiMe4, with the signal of the deuterated
solvent as reference, and d(P) in ppm rel. to 85% H3PO4; J in Hz; d(H) and d(P) accurate to Æ 0.01 and
Æ 0.1 ppm, resp., J(H,H) to Æ 0.3 Hz. ESI-MS: LC-Squire spectrometer; dry MeCN, CHCl3, or MeOH as
solvents; in m/z. FAB-MS: VG-AutoSpec spectrometer; in m/z. Elemental analyses (C, H, N) were carried out
by the Centre for Elemental Microanalysis of the Complutense University.
Bis[3,5-bis(4-butoxyphenyl)-1H-pyrazolato-kN1]bis(triphenylphosphine)digold(AuÀAu) ([{Au(pzbp )-
2
(PPh3)}2] (bp ˆ BuOC6H4) 1). To a soln. of 44 mg (0.084 mmol) of [Au(NO3)(PPh3)] in THF (20 ml) was
bp2
added Na(pzbp ) (obtained in situ from Hpz (30.7 mg, 0.084 mmol) and an excess of 60% NaH in THF
2
(15 ml)). After 24 h stirring, the produced white powder of NaNO3 was filtered and the colorless clear filtrate
evaporated. The residue was dissolved in CH2Cl2 and precipitated with hexane. IR(KBr): 1611 (CN). 1H-NMR
(CDCl3, r.t.): 7.81 (d, J ˆ 8.7, Ho); 7.54 7.44 (m, PPh3); 6.90 (d, J ˆ 8.7, Hm); 6.75 (s, HÀC(4)); 3.99 (t, J ˆ 6.5,
CH2O); 1.77 (m, CH2); 1.51 (m, CH2); 1.00 (t, J ˆ 7.3, Me). 31P{1H}-NMR (CDCl3, r.t.): 32.7. ESI-MS: 823.6
‡
([M ‡ H] ). Anal. calc. for C41H42AuN2O2P: C 59.9, H 5.2, N 3.4; found: C 59.7, H 5.2, N 3.5.
Bis{3,5-bis[4-(octyloxy)phenyl]-1H-pyrazolato-kN1}bis(triphenylphosphine)digold(AuÀAu) ([{Au(pzop )-
2
(PPh3)}2] (op ˆ C8H17OC6H4); 2). As described for 1, from 30 mg (0.057 mmol) of [Au(NO3)(PPh3)] and
27.4 mg (0.057 mmol) of Hpzop . IR(KBr): 1611 (CN). 1H-NMR (CDCl3, r.t.): 7.78( d, J ˆ 8.7, Ho); 7.54 7.44
2
(m, PPh3); 6.91 (d, J ˆ 8.7, Hm); 6.74 (s, HÀC(4)); 3.98( t, J ˆ 6.6, CH2O); 1.73 1.29 (m, (CH2)6); 0.89 (t, J ˆ 7.0,
‡
Me). 31P{1H}-NMR (CDCl3, r.t.): 32.9. ESI-MS: 935.6 ([M ‡ H] ). Anal. calc. for C49H58AuN2O2P: C 63.0, H
6.3, N 3.0; found: C 63.2, H 6.3, N 3.1.

Helvetica Chimica Acta Vol. 87 (2004)
2063
Fig. 3. Excitation and emission spectra of 1 in the solid state a) at 298 K and b) at 77 K
Bis{3,5-bis[4-(hexyloxy)phenyl]-1H-pyrazolato-kN1}bis(triphenylphosphine)digold(AuÀAu) ([{Au(pzhp )-
2
(PPh3)}2] (hp ˆ C6H13OC6H4); 3). As described 1, from 52 mg (0.101 mmol) of [Au(NO3)(PPh3)] and 42.5 mg
1
(0.101 mmol) of Hpzhp . IR(KBr): 1610 (CN). H-NMR (CDCl3, r.t.): 7.79 (d, J ˆ 8.5, Ho); 7.50 7.45 (m, PPh3);
2
6.91 (d, J ˆ 8.5, Hm); 6.75 (s, HÀC(4)); 3.99 (t, J ˆ 6.6, CH2O); 1.80 1.27 (m, (CH2)4); 0.92 (t, J ˆ 7.0, Me).
31P{1H}-NMR (CDCl3, r.t.): 32.8. FAB-MS: 878 (M ). Anal. calc. for C45H50AuN2O2P: C 61.5, H 5.7, N 3.2;
‡
found: C 61.4, H 5.6, N 3.0.

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Helvetica Chimica Acta Vol. 87 (2004)
{3,5-Bis[4-(octyloxy)phenyl-1H-pyrazolato-kN1}(triphenylphosphine)goldÀ{3,5-Bis[4-(octyloxy)phenyl-
op2
1H-pyrazole} ([Au(pzop )(PPh3)] ¥ (Hpz ) (op ˆ C8H17OC6H4); 4). To a soln. of 24 mg (0.0125 mmol) of
2
[{Au(pzop )(PPh3)}2] (2) in THF (20 ml) was slowly added a soln. of Hpz (14.6 mg, 0.025 mmol) in THF
op2
2
(15 ml). The mixture was stirred 24 h, and the resulting soln. evaporated. The residue was then dissolved in
CH2Cl2 and precipitated with hexane. IR(KBr): 3223 (NH), 1611 (CN). 1H-NMR (CDCl3, r.t.): 7.71 (d, J ˆ 8.7,
Ho); 7.53 7.43 (m, PPh3); 6.94 (d, J ˆ 8.7, Hm); 6.71 (s, HÀC(4)); 4.00 (t, J ˆ 6.3, CH2O); 1.73 1.29 (m, (CH2)6);
‡
1.00 (t, J ˆ 6.8, Me). 31P{1H}-NMR (CDCl3 , r.t.): 32.8. ESI-MS: 1409.1 ([M À H] ). Anal. calc. for
C80H102AuN4O4P: C 68.1, H 7.3, N 4.0; found: C 68.4, H 7.3, N 4.2.
X-Ray Structure Determination of 4. Colorless prismatic single crystals were obtained by slow diffusion of
hexane in a CH2Cl2 soln. of 4. The data were collected on a Bruker Smart-CCD diffractometer with graphite-
monochromated Mo-Ka radiation (l 0.71073 ä), operating at 50 kVand 20 mA. The data were collected over a
hemisphere of the reciprocal space by combination of three exposure sets. Each exposure of 10 s covered 0.38 in
w.The first 50 frames were recollected at the end of the data collection to monitor crystal decay. No appreciable
decay in the intensities of standard reflections was observed. A summary of the fundamental crystal and
refinement data is given in Table 2. Data were corrected for Lorentz and polarization effects, but not for
absorption. The structure was solved by direct methods and refined by full-matrix least-squares on F2 [14].
Anisotropic thermal parameters were used in the last cycles of refinement for all non-H-atoms with some
exceptions. All C-atoms of the octyloxy chains were refined with geometrical restraints and a variable common
CÀC distance. The C(62), C(63), and C(64) atoms showed non-resolvable positional disorder, and they were
refined anisotropically in two cycles, and in the subsequent cycles, their thermal parameters were kept constant.
The H-atoms were calculated and refined as riding on their C-bonded atom with a common isotropic
displacement parameter, except for H(3) which was found in a difference Fourier map, included, and refined as
riding on the N(3) atom.
Table 2. Crystal and Refinement Data for Compound 4
Formula
M
C80H102AuN4O4P
1411.59
Crystal system
Space group
triclinic
P1
≈
a/ä
11.1229(7)
b/ä
15.910(1)
c/ä
21.782(1)
a/8
72.494(1)
b/8
89.760(1)
g/8
U/ä3
84.520(1)
3658.0(4)
Z
2
F(000)
Dc/g cmÀ3
1472
1.282
Temp./K
298(2)
m(Mo-Ka)/mmÀ1
Crystal size/mm
Scan technique
Data collected
q/8
2.083
0.37 Â 0.23 Â 0.07
f and w
(À 11, À 18, À 23) to (13, 18, 25)
1.41 25.00
19263
Refls. collected
Unique refls.
Data, restraints, parameters
G.o.f. ( F2)
12682 (Rint ˆ 0.0275)
12682, 28, 794
1.109
0.041 (9775 refls.)
0.089
R(F) ((F2) > 2s(F2))a)
wR(F2) (all data)b)
Largest residual peak/e äÀ3
1.26
b
a) S[jFoj À j Fc j ]/S j Fo j . ) {S[w(Fo2 À Fc2)2]/S[w(Fo2)2]}1/2
.

Helvetica Chimica Acta Vol. 87 (2004)
2065
Supplementary crystallographic data have been deposited with the Cambridge Crystallographic Data
Center (CCDC deposition No. 231742). These data can be obtained free of charge via http://www.ccdc.cam.a-
c.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Center, 12 Union Road, Cambridge
CB2 EZ, UK; fax: ‡441223336033; e-mail: deposit@ccdc.cam.ac.uk).
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[1] a) H. Schmidbaur, Gold Bull. 1990, 23, 11; b) P. Pyykkˆ, Chem. Rev. 1997, 97, 597; c) P. Pyykkˆ, F.
Mendizabal, Chem. Eur. J. 1997, 3, 1458; P. Schwerdtfeger, A. E. Bruce, M. R. M. Bruce, J. Am. Chem. Soc.
1998, 120, 6587; d) M. C. Brandys, M. C. Jennings, R. J. Puddephatt, J. Chem. Soc., Dalton Trans. 2000,
4601.
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Received February 24, 2004