Governing the oxidative addition of iodine to gold(I) complexes by ligand tuning

Article abstract of DOI:10.1039/b403005b

The impact of addition of iodine to gold compounds which is strongly ligand-dependent and indicate a threshold in the oxidation potentials was investigated. A large series of tertiary phosphines were used as ligands for the oxidative addition of iodine. The reactions were followed by ³¹P NMR spectroscopy and the products crystallized from dichromethane-pentane solutions. Complexes with small triakylphosphines were readily oxidized, while those with more bulky ligands were not. No oxidation took place when the ligands were taken from the triaryphosphine series.

Full text of DOI:10.1039/b403005b

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Governing the oxidative addition of iodine to gold(I) complexes by
ligand tuning
Daniel Schneider, Annette Schier and Hubert Schmidbaur
Anorganisch-chemisches Institut, Technische Universität München, Lichtenbergstrasse 4,
85747 Garching, Germany
Received 27th February 2004, Accepted 15th April 2004
First published as an Advance Article on the web 26th April 2004
While several gold() complexes of the type (L)AuX (X = Cl, Br) are known to undergo oxidative addition of
elemental chlorine and bromine (X2), respectively, to give the corresponding gold() complexes (L)AuX3, the
addition of iodine to (iodo)gold() compounds is strongly ligand-dependent, suggesting a crucial threshold in the
oxidation potentials. A systematic investigation of this particular oxidative addition of iodine using a large series of
tertiary phosphines as ligands L has shown that both electronic and steric effects influence the course of the reaction.
The reactions were followed by 31P NMR spectroscopy and the products crystallized from dichloromethane–pentane
solutions. Complexes with small triakylphosphines (PMe3, PEt3) are readily oxidized, while those with more bulky
ligands (PiPr3, PtBu3) are not. With L taken from the triarylphosphine series [PPh3, P(2-Tol)3, P(3-Tol3), P(4-Tol)3]
no oxidation takes place at all, but mixed alkyl/aryl-phosphines [PMenPh3Ϫn] induce oxidation for n = 3 and 2, but
not for n = 1 and 0. However, in cases where no oxidation of the gold atoms is observed, the synthons may crystallize
as adducts with molecular iodine of the polyiodide type instead, which have an iodine rich stoichiometry. This fact
explains inconsistent reports in the literature. The metal atoms in (L)AuI coordination compounds with L
representing a tri(heteroaryl)phosphine [P(2-C4H3E)3, E = O, S], a phosphite [P(OR)3] or a trialkenylphosphine [PVi3]
are all not subject to oxidative addition of iodine. The dinuclear complex of the ditertiary phosphine Ph2PCH2PPh2,
(dppm)(AuI)2, gives an iodine adduct (without oxidation of the metal atoms), but with 1,2-Ph2P(C6H4)PPh2 (dppbe)
an ionic complex [(dppbe)AuI2]ϩI3Ϫ with a chelated gold() centre is obtained. The gold() bromide complexes with
tertiary phosphines are readily oxidized by bromine to give the corresponding gold() tribromide complexes, as
demonstrated for (BzMePhP)AuBr and (Ph3P)AuBr. With (dppm)(AuBr)2 the primary product with mixed oxidation
states was also isolated: (dppm)AuBr(AuBr3). The crystal structures of the following representative examples
and reference compounds have been determined: (Me3P)AuI3, (Me2PhP)AuI3, (iPr3P)AuIؒ1.5I2, (Ph3P)AuIؒI2,
{[(2-Tol)3P]AuI}2ؒI2, [(2-Tol)3P]AuI, (dppm)(AuX)2 (with X = Br, I), (dppm)AuBr(AuBr3) and [(dppbe)AuI2]ϩI3
The structures are discussed focusing on the steric effects. It appears that e.g. the reluctance of (Ph3P)AuI to
add I2 is an electronic effect, while that of (iPr3P)AuI has its origin in the steric influence of the ligand.
.
Ϫ
for an iodine molecule as a donor. There are no experimental
data available in the literature on any of the monomeric AuX3
molecules, except for an intercalate in the layer structure of the
superconductor Bi2Sr2CaCu2O8,15 which may require further
confirmation regarding the structure of the proposed AuI3 unit.
Introduction
Of the three coinage metals, only gold is readily oxidized to the
oxidation state ϩIII. This phenomenon is rationalized by
relativistic effects which play only a minor role for copper
(Z = 29) and silver (Z = 47), but are highly significant for the
description of the properties of gold (Z = 79).1–4 However, in
oxidation reactions with the halogens it is only for fluorine,
chlorine and bromine that the pure binary AuX3 compounds
can be obtained.5–8 The oxidation potential of iodine appears
to be not sufficient to make AuI3 or its oligomers stable com-
pounds. AuI is not oxidized by elemental iodine [eqn. (1)], and
substitution reactions starting with AuCl3 or AuBr3 and iodide
anions are associated with a redox process to give AuI and I2
[e.g. eqn. (2)].9–11
For ternary or more complex phases with gold and iodine,
the occurrence not only of the [AuI2]Ϫ anion with Auϩ, but
also of the [AuI4]Ϫ anion with Au3ϩ is well documented.5,12,16,17
Apparently, there is a redox equilibrium connecting the anions
[AuI2]Ϫ and [AuI4]Ϫ [eqn. (3)],18 but it represents a delicate
balance depending one several parameters which decide if
oxidative addition of iodine will occur or not. This is obvious
from a few, at first sight, quite confusing observations:
compounds of the type [H3N(CH2)nNH3]2[AuI2][AuI4][I3]2
were shown to contain both [AuI2]Ϫ and the iodine carrier
anions [I3]Ϫ, and yet no redox reaction takes place.19 In
other ammonium or sulfonium polyiodogold salts like
[NH4]2[AuI4]2[I2], [Et3S][AuI4][I2]2 and [Me3S][AuI4][I3] all the
gold is oxidized to Au3ϩ and the excess iodine is part of a
AuI ϩ I → AuI
(1)
(2)
(3)
/
2
3
(AuCl3)2 ϩ 6IϪ
[AuI2]Ϫ ϩ I2
2AuI ϩ 2I2 ϩ 6ClϪ
[AuI4]Ϫ
(4)
In recent quantum-chemical calculations the molecular
geometries and electronic structures of AuI3 and (AuI3)2 have
been determined for the gas phase.12–14 It appears that AuI3
could be expected to have an “L-shaped” structure (A) rather
than the standard T-shaped or Y-shaped structures (B, C)
calculated for AuF3 or AuCl3. In form A the gold atom is not
in a higher oxidation state but rather acts as an acceptor centre
triodide or of
a
gold polyiodide network,12,20 while in
Cs2[AuI2][AuI4] the Auϩ and Au3ϩ states coexist in separate
anions.5,21 Finally, [Et3S][AuI2] and [Et3S][AuI4] are simple
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4
D a l t o n T r a n s . , 2 0 0 4 , 1 9 9 5 – 2 0 0 5
1995

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Table 1 31P{1H} NMR data of (L)AuI complexes (L = tertiary
reference compounds which contain solely [AuI2]Ϫ and [AuI4]Ϫ
anions, respectively, of which the latter is perfectly stable.12
A similar complexity of results is documented for donor–
acceptor complexes of the type (L)AuI3. A compound of this
stoichiometry of the phosphine and arsine series, (Et3P)AuI3,
was first obtained as black needles (mp 77 ЊC) by addition of
iodine to colourless (Et3P)AuI,22 but only elemental analysis
data were used for identification [eqn. (4)]. (Me3As)AuI3 was
prepared by reacting gold powder with Me3AsI2, and struc-
turally characterized as a square-planar Au3ϩ complex.23 In
the analogous reaction with Me3PI2 only the 2 : 1 complex
(Me3P)2AuI3 was obtained and shown to have a trigonal-
bipyramidal structure. From 31P NMR data it was concluded
that this compound loses one of the two PMe3 ligands in
solution.23 The 31P NMR shifts given for (Me3P)AuI3 (δ 30.1
ppm)23 are not in agreement with the present results (δ Ϫ11.2
ppm, below). In another investigation24 of the reaction between
(Me3P)AuMe with I2 the 1 : 1 complex (Me3P)AuI3 was not
isolated. (Ph3P)AuI was found to give only a black oily product
on addition of I2, which showed a 31P resonance identical
with that of the starting material, indicating that no oxidative
addition had taken place.25 The same behaviour was observed
phosphine) and the products obtained upon addition of equivalent
quantities of elemental iodine in dichloromethane solution at 20 ЊC
(δ values in ppm relative to the external 85% aqueous phosphoric acid
standard). Bold face numbers indicate oxidation to gold(), backslash
refers to an equilibrium
Phosphine ligand L
(L)AuI
(L)AuI ϩ I2
Me3P
2.6
40.7
71.1
97.4
13.8
25.1
39.4
19.2
39.5
37.9
27.5
Ϫ20.8
2.6
؊11.2
27.5
Et3P
iPr3P
71.8
tBu3P
97.5
13.8/؊10.3
25.1
39.3
19.5
39.6
38.3
27.5/؊12.1
Ϫ20.7
2.9
132.3
119.8
28.1
Me2PhP
MePh2P
Ph3P
(2-Tol)3P
(3-Tol)3P
(4-Tol)3P
Vi3P
(2-Fur)3P
(2-Thi)3P
(MeO)3P
(PhO)3P
dppm
132.3
119.9
28.0
for P-phenyldibenzophosphole.25 However, in another study24
a
compound formulated as “(Ph3P)AuI3” was used as a substrate
for the reaction with Cd(CF3)2 which led to the formation
of the gold() complex (Ph3P)AuCF3. The dinuclear gold()
complex of bis(diphenylphosphino)methane (dppm) of the
composition (dppm)(AuI)2 was reacted with iodine and
shown to yield a crystalline product of the stoichiometry
(dppm)(AuI2)2, but its 197Au Mössbauer spectrum surprisingly
suggested that the gold atoms in this tetraiodide were still in
the oxidation state ϩ1. In the absence of structural data, the
formation of gold() polyiodides was proposed.26
With sulfur ligands, stable complexes of the type (R2S)AuI3
could only be prepared with chelating donor molecules such
as MeSCH2CH2SMe, which are assumed to have an ionic
structure [(CH2SMe)2AuI2]I.27 Salts with iodide or triiodide
anions associated with cyclic cations in which Au3ϩ is co-
ordinated to two sulfur and two iodine atoms are also produced
in the oxidation of gold with β-dithioketones and iodine.28,29
From this collection of references it is obvious that the
oxidative addition of iodine to AuI, [AuI2]Ϫ and (L)AuI com-
plexes [eqns. (1), (3) and (4)] is strongly dependent on the
environment (gas, solvent, crystal packing) and on the qualities
of ligands L. Because oxidation of gold metal and gold
compounds with mild and environmentally benign oxidants like
iodine is of great current interest in nanotechnology, we have
initiated a systematic study of such processes and report herein
a first set of our results.
Bis(diphenylphosphino)methane (dppm) was used for the
preparation of the 1 : 2 complexes with AuBr and AuI. Both
had been prepared previously.26,30
The crystal and molecular structures of a few representative
examples have been determined – intentionally or unintention-
ally – in order to identify the nature of a product or to have
reference data for the corresponding addition products. Among
others these include (dppm)(AuI)2 and (dppm)(AuBr)2 giving
access to data of a complete set of complexes (together with
the known structure of (dppm)(AuCl)2)31a as a reference. The
(L)AuX (X = Br, I) structures show no anomalies. The com-
plexes investigated bear large phosphine ligands which prevent
aggregation via aurophilic or other closed-shell interactions4
(see below).
Attempted oxidative addition of iodine
As a rule, the substrates of the type (R3P)AuI were initially
treated with an equimolar quantity of elemental iodine in
dichloromethane at Ϫ78 ЊC, and the reaction mixtures were
then allowed to warm up slowly to room temperature. Violet to
black solutions of the products were obtained which were
investigated by 31P NMR spectroscopy. The change in chemical
shifts of the ligand resonance gave a first indication as to
whether the oxidation was successful or not, since a transform-
ation from (L)AuI to (L)AuI3 leads to an up-field shift of the 31
P
signal. This upfield shift may seem to be unexpected, but similar
results have been observed for complexes of tertiary phosphines
with other metal() halides.31b
Preparative studies
As shown in Table 1, only very few mononuclear complexes
were really undergoing oxidative addition of iodine to the metal
centre, and certain rules emerge on inspection of the formulae
and the data: The inductive effect of trialkylphosphines, which
are potent σ-donor molecules, clearly favours iodine addition,
as demonstrated for L = PMe3, PEt3. By contrast, the poorer
triarylphosphine donors appear to have an adverse effect
[L = PPh3, P(4-MeC6H4)3 etc.]. This difference is due to electro-
nic effects, and not to steric effects, since the cone angles of
e.g. PEt3 and PPh3 differ only by about 10Њ.32
(Phosphine)gold(I) iodides
While a large number of 1 : 1 complexes of tertiary phosphines
with AuCl and AuBr have been prepared and structurally
characterized, the analogous coordination compounds of AuI
are smaller in number. All of them have been prepared by
metathesis reactions of the chloride complexes with alkali
iodides [eqn. (5)]. In the present study this method – executed
(L)AuCl ϩ KI
(L)AuI ϩ KCl
(5)
in a two-phase system – was used for the new mononuclear
As the donor strength of PR3 is reduced by stepwise
substitution of methyl by phenyl groups along the series
PMe3 – PMe2Ph – PMePh2 – PPh3, the oxidative addition is
also gradually inhibited: With (Me3P)AuI the oxidation with I2
goes to completion in solution, and (Me3P)AuI3 is isolated as a
crystalline solid in quantitative yield. For (Me2PhP)AuI and I2
there is a temperature-dependent equilibrium between the
species formulated in eqn. (4), which is easily followed in the
compounds (iPr3P)AuI, (MePh2P)AuI, [(2-MeC6H4)3P]AuI,
[(3-MeC6H4)3P]AuI,
[(4-MeC6H4)3P]AuI,
(Vi3P)AuI,
[(2-C4H3O)3P]AuI, [(2-C4H3S)3P]AuI, [(MeO)3P]AuI and
[(PhO)3P]AuI. The products were generally obtained in high
yields as colourless crystalline solids. They were employed as
substrates for the oxidative addition of iodine along with a
series of known mononuclear compounds (Table 1).
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31P NMR spectrum. Crystals of (Me2PhP)AuI3 dissolved in
CD2Cl2 at 20 ЊC show again partial dissociation [eqn. (4)] as
demonstrated by 31P NMR spectroscopy. Both (MePh2P)AuI
and (Ph3P)AuI undergo no oxidative addition of iodine.
Tri(heteroaryl )phosphines such as tri(2-furyl)- and tri(2-
thienyl)phosphine have a similar ligand effect: Their AuI com-
plexes are not oxidized by iodine. This result is in agreement
with previous studies where both ligands were shown that their
electronic and steric effects are comparable to that of PPh3.33
The poor donors of the phosphite series, P(OMe)3 and
P(OPh)3,32 also yield AuI complexes which do not undergo
oxidative addition of I2.
Structural studies
Triiodo(trimethylphosphine)gold, (Me3P)AuI3, forms black,
solvent-free monoclinic crystals (from dichloromethane–n-
pentane, space group P21/c, Z = 4) which are not isomorphous
with the analogous arsine complex.23 The molecules have the
square-planar structure typical of a low-spin d8-complex of
Au3ϩ (Fig. 1). The Au1–I3 distance (for the iodine atom trans to
the ligand) is significantly longer than the Au1–I1/I2 distances
(cis to the ligand). There are minor deviations of the cis-I–Au–
I/I–Au–P angles from 90Њ, but the sum of these angles [359.29Њ]
is almost exactly 360Њ.
Trivinylphosphine34 with a cone angle in the region of that of
triethylphosphine forms a gold() complex (Vi3P)AuI which is
partially transformed into the gold() complex (Vi3P)AuI3 in
CD2Cl2 at 20 ЊC, indicating a lower donor character of PVi3 as
compared to PEt3. As the alkyl or alkenyl groups become larger,
steric effects become important: both [iPr3P]AuI and [tBu3P]AuI
are not oxidized by iodine.
All the observations summarized in Table 1 relate to equi-
libria in solution, for which the results are unambiguous. The
stoichiometry found for crystalline products has for some
time been confusing, because the analytical composition
seemed to indicate oxidation of gold() even in cases where
the spectroscopic data (NMR, Mössbauer, ESCA) left no
doubt that the oxidation state of the metal was unaltered
after addition of iodine. The present studies have shown that
crystals of all of these intriguing iodine-rich products are
supramolecular aggregates of the gold() complexes with
molecular iodine.
Single crystals of true gold() complexes of the type (L)AuI3
could only be obtained for (Me3P)AuI3 and (Me2PhP)AuI3ؒ
0.75CH2Cl2. The molecules show the expected square planar
mode of coordination (below). The structures of (Et3P)AuI3
and (Vi3P)AuI3, which also contain gold(), could not
yet be determined, but are expected to have similar
geometries.
Iodo[tri(isopropyl)phosphine]gold() crystallizes with iodine
in the molar ratio 2 : 3, i.e. (iPr3P)AuIؒ1.5I2. The components
form two-dimensional networks, with iodine molecules
bridging an array of equivalent complex molecules. It is only
in this case that the contacts of the iodine molecules are
maintained side-on at the Au–I bonds indicating an approach
of the oxidant which comes to a premature standstill and does
not lead to a full oxidative addition.
The compound of stoichiometry (Ph3P)AuI3 already
mentioned in the literature was shown to be an aggregate
(Ph3P)AuIؒI2 with I2 molecules bridging the iodo ligands of
neighbouring complexes in zigzag chains. For the crystals
grown from solution containing equimolar quantities of
[(2-MeC6H4)3P]AuI and I2 the stoichiometry is {[(2-MeC6-
H4)3P]AuI}2ؒI2 with each iodine molecule bridging a pair of
complexes. All sub-van der Waals contacts are between iodine
atoms. There is no evidence for an approach of iodine
molecules towards the gold centres. Details of the structures
are discussed below, together with those of the reference
compounds (Ph3P)AuBr3, (MeBzPhP)AuBr3, (dppm)(AuX)2
(X = Br, I) and (dppm)AuBr(AuBr3)ؒ2CH2Cl2.
Fig. 1 Molecular structure of (Me3P)AuI3 (ORTEP drawing with 50%
probability ellipsoids, H-atoms omitted for clarity). Selected bond
lengths (Å) and angles (Њ): Au1–P1 2.334(2), Au1–I1 2.6235(5), Au1–I2
2.6176(5), Au1–I3 2.6572(5); P1–Au1–I1 92.94(4), P1–Au1–I2 87.61(4),
P1–Au1–I3 175.70(4), I1–Au1–I2 175.95(2), I1–Au1–I3 90.03(2),
I2–Au1–I3 89.21(2).
(Dimethylphenylphosphine)triiodogold is obtained from
dichloromethane–n-pentane as black monoclinic crystals
(Me2PhP)AuI3ؒ0.75CH2Cl2, space group C2/c with Z = 16. The
asymmetric unit contains two independent molecules of
the complex and 1.5 molecules of solvent. A superposition
of the two complexes (one of which is presented in Fig. 2) has
shown that their structures differ only in the conformation of
the phenyl group, i.e. the dihedral angles Au1–P1–C111–C112
[124.8(6)Њ] and Au2–P2–C211–C212 [89.9(6)Њ]. The gold atoms
are in a square-planar coordination. Like for (Me3P)AuI3, the
distances Au1–I2 and Au2–I4 (trans to P) are slightly longer
than the Au–I(cis) distances, and the angles cis-I–Au–I/P–Au–I
are all close to 90Њ. An inspection of the structures of (Me3P)-
AuI3 and (Me2PhP)AuI3 shows that the ligands leave enough
The oxidation of gold with iodine in the presence of the
dppbe ligand in dichloromethane gave a crystalline product
of the composition (dppbe)AuI5 which was shown to have an
Ϫ
ionic structure [(dppbe)AuI2]ϩI3 [eqn. (6)]. This was the only
product obtained directly from gold metal, the ligand and
iodine. All other ligands were also found to assist the
dissolution of gold metal in the presence of iodine, in agree-
ment with results obtained earlier with polyhalides of tertiary
phosphines and arsines.23 These experiments will be described
in a different context in future accounts.
Fig. 2 Molecular structure of (Me2PhP)AuI3 (ORTEP drawing with
50% probability ellipsoids, H-atoms omitted for clarity). Selected bond
lengths (Å) and angles (Њ) [the corresponding values of the second,
crystallographically independent molecule are given in parentheses]:
Au1–P1 2.344(2) [2.345(2)], Au1–I1 2.6231(5) [2.636(6)], Au1–I2
2.6493(5) [2.6511(5)], Au1–I3 2.6242(5) [2.6228(5)]; P1–Au1–I1 92.95(5)
[92.61(5)], P1–Au1–I2 176.98(5) [175.44(5)], P1–Au1–I3 88.81(5)
[89.88(6)], I1–Au1–I2 89.72(2) [89.30(2)], I1–Au1–I3 171.51(2)
[177.43(2)], I2–Au1–I3 88.76(2) [88.17(2)].
Ϫ
dppbe ϩ 2.5I2 ϩ Au
[(dppbe)AuI2]ϩI3
(6)
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room for two iodine atoms to approach the gold atoms at right
angles to the molecular axis. For (iPr3P)AuI this is no longer
true:
The aggregation of the components leads to the formation
of two-dimensional arrays, in which zigzag chains
ؒ ؒ ؒ Au1 ؒ ؒ ؒ I4–I5 ؒ ؒ ؒ Au1A ؒ ؒ ؒ I4A–I5A ؒ ؒ ؒ Au1B ؒ ؒ ؒ can
be recognized which are linked into corrugated sheets by the
ؒ ؒ ؒ Au1 ؒ ؒ ؒ I3–I3A ؒ ؒ ؒ Au1A ؒ ؒ ؒ contacts (Fig. 4). These
sheets are stacked in an –ABABAB– sequence, because in
every second sheet the zigzag chains are inverted as related by a
twofold axis.
Iodo[tri(isopropyl)phosphine]gold sesqui(diodine), (iPr3P)-
AuIؒ1.5I2, precipitated from a solution of the components in
dichloromethane upon slow diffusion of n-pentane, forms
orthorhombic crystals (space group C2221, Z = 8 formula units
in the unit cell). The asymmetric unit contains one (iPr3P)AuI
complex, one complete iodine molecule and one iodine atom
which is related to the other half of its I2 molecule by symmetry.
The mode of supramolecular aggregation of the components
makes this compound the most interesting example of the
whole series: The iodine molecules are found to approach the
(iPr3P)AuI molecules end-on and midway between the Au1–I1
bond. This happens in two different ways, one of which
produces a symmetrical I2 bridge between two complexes with a
twofold axis passing through the midpoint of the I2 molecule
(Fig. 3(a)). The second type of I2 bridge has very similar
distances and angles, but is unsymmetrical and connects two
complexes which are inverted (head-to-tail, Fig. 3(b)). In both
cases the Au1 ؒ ؒ ؒ I3/I4/I5 and I1 ؒ ؒ ؒ I3/I4/I5 distances are of
comparable lengths (in the range 3.556 to 3.861 Å).
Fig. 4 View along the a-axis of the cell, showing the ؒ ؒ ؒ ABAB ؒ ؒ ؒ
stacking of inverted zigzag chains (right and left side) formed by the
components of (iPr3P)AuIؒ1.5I2. These chains are linked by iodine
molecules (centre) into sheets.
(Triphenylphosphine)gold “triodide”, as crystallized from
CH2Cl2–n-pentane, is monoclinic, space group P21/n with Z = 4,
and is composed of equimolar amounts of the components,
(Ph3P)AuIؒI2. The iodine atoms form zigzag chains as shown in
Fig. 5, the iodide atom I1 attached to the gold atom being in a
bridging position between two iodine molecules with almost
symmetrical contacts I1–I2A [3.4361(5) Å] and I1–I3 [3.5782(5)
Å], and a large angle I2A–I1–I3 of 122.6(1)Њ (Fig. 5). The iodine
molecules approach the principal axis P1–Au1–I1 at the iodine
atom I1 at approximately right angles and therefore there is no
evidence for iodine coordination (and oxidation) of I2 and I3
to/of the metal atom. The I2–I3 distance of the I2 molecule
[2.7331(5) Å] deviates only marginally from the standard bond
length in orthorhombic iodine [2.667(1) Å], suggesting weak
intermolecular interactions.
Fig. 5 The structure of (Ph3P)AuIؒI2, with the (Ph3P)AuI unit acting
as a bridge between two I2 molecules (ORTEP drawing with 50%
probability ellipsoids, H-atoms omitted for clarity). Selected bond
lengths (Å) and angles (Њ): Au1–P1 2.258(2), Au–I1 2.5806(3), I1–I2a
3.4361(5), I1–I3 3.5782(5), I2–I3 2.7331(5); P1–Au1–I1 176.14(3),
I1–I2a–I3a 176.9(1), I1–I3–I2 171.4(1), I2a–I1–I3 122.6(1).
Fig. 3 Modes of supramolecular aggregation of the components in
(iPr3P)AuIؒ1.5I2 (ORTEP drawing with 50% probability ellipsoids, H-
atoms omitted for clarity). Selected bond lengths (Å) and angles (Њ):
molecule (a): Au1–P1 2.271(1), Au1–I1 2.5776(3), I3–I3A 2.7470(7),
I1 ؒ ؒ ؒ I3 3.647(1), Au1 ؒ ؒ ؒ I3 3.564(1); P1–Au1–I1 176.23(3); molecule
(b): I4–I5 2.7078(5), I1 ؒ ؒ ؒ I4 3.863(1), I1A ؒ ؒ ؒ I5 3.614(1), Au1 ؒ ؒ ؒ I4
3.504(1), Au1A ؒ ؒ ؒ I5 3.556(1).
It should be noted that the space around the metal atom in
(Ph3P)AuI is not very crowded and that there would be access
of iodine atoms or molecules at right angles at the gold atom.
That this is true can be deduced from the structure of
(Ph3P)AuBr3 which was determined as a reference.
The deep red crystals of tribromo(triphenylphosphine)gold
are monoclinic, space group P21 with Z = 2, and contain
molecules with a square-planar coordination geometry at the
It appears that for steric reasons the iodine atoms cannot
become attached to the gold atoms at right angles as required
for a regular oxidative addition, but are kept at a distance where
only weak bonding can be established. Accordingly, the I–I
distances in the iodine molecules show no significant
lengthening [I3–I3A 2.7470(7), I4–I5 2.7078(5) Å].
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gold atom (Fig. 6(a)). The Au1–Br3(trans to P) bond is longer
than the Au1–Br1/Br2(cis to P) bonds and the angles Br–Au–
Br are close to 90Њ. It is obvious from Fig. 6(a) that with iodine
instead of bromine atoms there would still not be any signifi-
cant steric hindrance for the tetracoordination of the gold
atom. The failure of the oxidative addition of iodine to
(Ph3P)AuI is thus not a steric effect, but a consequence of the
electronic influence of the PPh3 ligand as compared to the PMe3
or PEt3 ligands which have been found to support this addition.
It should be noted that in a previous publication another
monoclinic modification of (Ph3P)AuBr3 has been described
(space group P21/c, a = 9.189, b = 26.703, c = 10.065 Å,
β = 95.76Њ).35 The molecular dimensions are similar.
Fig. 7 Molecular structure of [(2-Tol)3P]AuI (ORTEP drawing with
50% probability ellipsoids, H-atoms omitted for clarity). Selected bond
lengths (Å) and angles (Њ), [the corresponding values of the second,
crystallographically independent molecule are given in parentheses]:
Au1–P1 2.271(1) [2.264(1)], Au1–I1 2.5681(4) [2.5544(5)]; P1–Au1–I1
176.35(4) [175.19(4)].
clearly pose steric hindrance to large atoms approaching the
gold atom.
From solutions in dichloromethane containing iodine the
same compound crystallizes as the orange 2 : 1 solvate, {[(2-
¯
MeC6H4)3P]AuI}2ؒI2 (triclinic, space group P1, Z = 2). The
components are arranged in groups consisting of one iodine
molecule flanked by two complex molecules with a centre of
inversion located at the mid-point of the I2 molecule (Fig. 8).
The iodine molecule shows no major change of its interatomic
distance [2.7389(6) Å] and the contacts I1–I2 are long at
3.441(1) Å. The axis I1–I2–I2A–I1A is almost linear and the
angles Au1–I1–I2 are small at only 68.1Њ. These trimolecular
units are further aggregated through even longer I1–I1A con-
tacts [4.189(1) Å] to give zigzag chains along the a axis of the
crystal. The supramolecular aggregate thus shows the features
of typical metal iodide/iodine adducts as recently reviewed.12b
Fig. 6 (a) Molecular structure of (Ph3P)AuBr3 (ORTEP drawing with
50% probability ellipsoids, H-atoms omitted for clarity). Selected bond
lengths (Å) and angles (Њ): Au1–P1 2.3282(9), Au–Br1 2.4170(4),
Au–Br2 2.4251(4), Au–Br3 2.4554(4); P1–Au1–Br1 92.19(3), P1–Au1–
Br2 88.18(3), P1–Au1–Br3 177.48(3), Br1–Au1–Br2 175.11(2),
Br1–Au1–Br3 90.18(2), Br2–Au1–Br3 89.54(2). (b) Molecular structure
of (BzMePhP)AuBr3 (one enantiomer, ORTEP drawing with 50%
probability ellipsoids, H-atoms omitted for clarity). Selected bond
lengths (Å) and angles (Њ): Au1–P1 2.312(2), Au1–Br1 2.4124(9), Au1–
Br2 2.4240(9), Au1–Br3 2.468(1); P1–Au1–Br1 92.19(5), P1–Au1–Br2
86.73(5), P1–Au1–Br3 174.49(5), Br1–Au1–Br2 178.91(3), Br1–Au1–
Br3 89.97(4), Br2–Au1–Br3 91.13(4).
Fig. 8 Structure of {[(2-Tol)3P]AuI}2ؒI2, with the I2 molecule bridging
two [(2-Tol)3P]AuI units (ORTEP drawing with 50% probability
ellipsoids for the heavy atoms, H-atoms omitted for clarity). Selected
bond lengths (Å) and angles (Њ): Au1–P1 2.2662(9), Au1–I1 2.5591(3),
I2–I2a 2.7389(6), I1–I2 3.441(1); P1–Au1–I1 176.81(2), I1–I2–I2a
176.11(1).
As a model AuBr3 complex with a mixed alkyl-/aryl-
substituted phosphine, the structure of (benzyl(methyl)phenyl-
phosphine)tribromogold was structurally characterized. The
molecules in crystalline (BzMePhP)AuBr3 (monoclinic, space
group P21/c, Z = 4) are square-planar complexes (Fig. 6(b))
with dimensions very similar to those of (Ph3P)AuBr3 (above).
The molecules are chiral and the crystal contains both
enantiomers.
Iodo[tri(2-tolyl)phosphine]gold crystallizes from dichloro-
methane–n-pentane as colourless needles (orthorhombic, space
group Pbca, Z = 16). The asymmetric unit contains two
independent molecules with very similar bond lengths and
angles but different conformations of the phosphine ligands
(Fig. 7). In both cases a propeller configuration is observed
with all methyl groups oriented towards the gold atoms which
Crystals of (dppm)(AuBr)2 and (dppm)(AuI)2 are isomorph-
ous together with those of the chloro analogue, (dppm)(AuCl)2
(monoclinic, space group C2/c, Z = 4).31 Only the iodide
is shown in Fig. 9. A crystallographic twofold axis passing
through the methylene carbon atoms and bisecting the P–C–P
angles relates the two halves of the molecules. The conform-
ational twist holds the gold atoms at a distance of 3.444(1) Å
for the AuBr complex and of 3.575(1) Å for the AuI complex.
This indicates only very weak aurophilic interactions in both
cases. Any closer approach would obviously lead to steric
hindrance in other parts of the molecule. The 1 : 1 addition
compound with I2 described previously26 could not be crystal-
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Fig. 11 Structure of the cation of [(dppbe)AuI2]ϩ[I3]Ϫ (ORTEP
drawing with 50% probability ellipsoids, H-atoms omitted for clarity).
Selected bond lengths (Å) and angles (Њ): Au1–P1 2.329(2), Au1–P2
2.334(1), Au1–I1 2.6342(4), Au1–I2 2.6248(4) P1–Au1–P2 85.71(5),
P1–Au1–I1 176.68(4); P2–Au1–I1 91.91(4), P1–Au1–I2 91.75(4),
P2–Au1–I2 177.36(4), I1–Au1–I2 90.60(2).
Fig. 9 Molecular structure of (dppm)(AuI)2 (ORTEP drawing with
50% probability ellipsoids, H-atoms omitted for clarity). Selected bond
lengths (Å) and angles (Њ): Au1–P1 2.253(1), Au1–I1 2.5604(4),
Au1 ؒ ؒ ؒ Au1A 3.575(1); P1–Au1–I1 178.29(3).
lized. It is expected to have an inclusion type structure similar
to that of the triarylphosphine complexes (above).
However, the product of the 1 : 1 oxidative addition of brom-
ine to (dppm)(AuBr)2 of the formula (dppm)AuBr(AuBr3) was
obtained as red crystals of the bis-dichloromethane solvate
(monoclinic, space group P21/n, Z = 4). This complex has one
linearly two-coordinate Auϩ centre while the other is a square-
planar tetracoordinate Au3ϩ (Fig. 10). The geometrical details
of the two parts resemble quite closely those of (Ph3P)AuBr
and (Ph3P)AuBr3 (above). The product of complete bromin-
ation of the composition (dppm)(AuBr3)2 was not crystallized.
197Au Mössbauer spectra obtained for a related mixed chloro/
bromo compound of this type have shown that the product has
two equivalent gold() centres.26
Fig. 12 Interionic contacts in the structure of [(dppbe)AuI2]ϩ[I3]Ϫ
(ORTEP drawing with 50% probability ellipsoids for the heavy atoms,
H-atoms omitted for clarity). Selected bond lengths (Å) and angles (Њ):
I3–I4 2.8811(6), I4–I5 2.9420(6), I1 ؒ ؒ ؒ I3 3.773(1), I2 ؒ ؒ ؒ I4A
4.069(1); I3–I4–I5 179.23(2).
Conclusions
From the results of the present study it appears that the
oxidative addition of iodine to gold() complexes of the formula
(L)AuI is strongly dependent on the nature of the ligand L:
Gold() centres conditioned by a strong σ-donor ligand of
the trialkylphosphine series undergo rapid and quantitative
conversion to (L)AuI3 complexes (L = PMe3, PEt3). With these
ligands the oxidation potential of the complexes is clearly
shifted beyond the threshold determined by the oxidation
potential of elemental iodine. As the steric bulk of the sub-
stituents is growing, the addition of iodine leads to adducts
in which the approach of the I2 molecules to the gold centre
does not quite reach the standard Au–I bonding distance
{(iPr3P)AuIؒ1.5I2} and no oxidation of the gold atom can
occur.
Gold() centres with poorer σ-donor ligands taken from
the triaryl- or triheteroaryl-phosphine series do not undergo
oxidative addition of iodine as demonstrated for triphenyl-
phosphine, the three isomeric tritolylphosphines, as well
as tri(2-furyl)- and tri(2-thienyl)phosphine. Trimethyl- and
triphenylphosphite are in the same category. These ligands are
thus not shifting the oxidation potential beyond the said
threshold, but following the series (MenPh3Ϫn)P with n = 3, 2, 1,
0, there is complete addition for n = 3, an equilibrium for n = 2,
and no reaction at all for n = 1 and 0 [eqn. (7)], indicating
a stepwise shift towards and across the borderline of the
electrochemical potential of the reaction partner. With the
Fig. 10 Molecular structure of (dppm)AuBr(AuBr3) (ORTEP drawing
with 50% probability ellipsoids, H-atoms omitted for clarity). Selected
bond lengths (Å) and angles (Њ): Au1–P1 2.317(1), Au1–Br1 2.4319(6),
Au1–Br2 2.4555(5), Au1–Br3 2.4240(6), Au2–P2 2.241(1), Au2–Br4
2.4040(5); P1–Au1–Br1 93.06(3), P1–Au1–Br2 176.38(3), P1–Au1–Br3
88.00(3), Br1–Au1–Br2 88.83(2), Br1–Au1–Br3 169.78(2), Br2–Au1–
Br3 89.59(2), P2–Au2–Br4 178.95(3).
The compound obtained from the reaction of metallic gold
with iodine and dppbe has the composition [(dppbe)AuI2]ϩI3
.
Ϫ
The crystals are monoclinic, space group P21/n with Z = 4
formula units in the unit cell. In the cation the gold() centre is
chelated by the ligand and its square-planar coordination
sphere is complemented by two iodide anions (Fig. 11). The
structure of the cation approaches mirror symmetry quite
closely, but point group Cs is not imposed crystallographically.
The triiodide anion is linear [I3–I4–I5 179.23(2)Њ] with slightly
different bond lengths: I3–I4 2.8811(6), I4–I5 2.9420(6) Å.
There are interionic contacts I1 ؒ ؒ ؒ I3 of 3.773(1) and
I2 ؒ ؒ ؒ I4A of 4.069(1) Å which indicate only weak association
(Fig. 12). Geometrical details are given in the caption to Fig. 11.
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simplest trialkenylphosphine, Vi3P, the addition of iodine is
Iodo(methyldiphenylphosphine)gold(I). 300 mg (0.70 mmol,
also incomplete.
1 eq.) (MePh2P)AuCl and 581 mg (3.5 mmol, 5 eq) KI; 298 mg
(81% yield), mp 147 ЊC (Found: C, 29.86; H, 2.46; I, 24.3. Calc.
for C13H13AuIP: C, 29.79; H, 2.50; I, 24.2%). NMR (CD2Cl2),
1H: δ 7.69–7.49 (m, 10 H, Ph); 2.14 (d, JHP = 10.4 Hz, 3 H, Me).
31P{1H}: δ 25.1 (s).
[(MenPh3Ϫn)P]AuI ϩ I2
[(MenPh3Ϫn)P]AuI3
(7)
The dinuclear complex (dppm)(AuI)2, derived from the
dppm ligand which has a substitution pattern like MePh2P
and poor chelating properties (owing to the formation of
strained four-membered rings), is also not oxidized by iodine.
By contrast, the more powerful oxidant bromine is readily
added to (dppm)(AuBr)2 to give first (dppm)AuBr(AuBr3)
and finally (dppm)(AuBr3)2. This result indicates that the
failure of oxidative addition of iodine to (Ph3P)AuI, (MePh2P)-
AuI and (dppm)(AuI)2 is not a steric effect but is due to
the poor donor qualities of the arylphosphine ligands, and
this reasoning is supported by the results of the structural
studies.
The ligand dppbe with a rigid skeleton predisposed to
chelation forms a stable mononuclear gold() complex with
an ionic structure [(dppbe)AuI2]ϩI3Ϫ. Chelation of gold cations
by phosphine thus is found to assist in the oxidation process
even with fully aryl-substituted ligands.
Iodo[tri(2-tolyl)phosphine]gold(I). 300 mg (0.56 mmol, 1 eq.)
[(2-MeC6H4)3P]AuCl and 465 mg (2.8 mmol, 5 eq.) KI; 316 mg
(90% yield), mp 279–282 ЊC with decomposition (Found: C,
39.91; H, 3.28; I, 20.2. Calc. for C21H21AuIP: C, 40.15; H, 3.37;
1
I, 20.2%). NMR (CD2Cl2), H: δ 7.64–6.92 (m, 12 H, C6H4);
2.69 (s, 9 H, Me). 31P{1H}: δ 19.2 (s).
Iodo[tri(3-tolyl)phosphine]gold(I). 300 mg (0.56 mmol, 1 eq.)
[(3-MeC6H4)3P]AuCl and 465 mg (2.8 mmol, 5 eq.) KI; 300 mg
(85% yield), mp 173–175 ЊC with decomposition (Found: C,
40.13; H, 3.23; I, 19.6. Calc. for C21H21AuIP: C, 40.15; H, 3.37;
1
I, 20.2%). NMR (CD2Cl2), H: δ 7.51–7.13 (m, 12 H, C6H4);
2.36 (s, 9 H, Me). 31P{1H}: δ 39.5 (s).
Iodo[tri(4-tolyl)phosphine]gold(I). 300 mg (0.56 mmol, 1 eq.)
[(4-MeC6H4)3P]AuCl and 465 mg (2.8 mmol, 5 eq.) KI; 309 mg
(88% yield), mp 340–341 ЊC with decomposition (Found: C,
39.96; H, 3.32; I, 19.9. Calc. for C21H21AuIP: C, 40.15; H, 3.37;
The structures of the gold() and gold() complexes of
the types (L)AuI and (L)AuI3 determined in this study have
standard linear and square-planar geometries, respectively.
There are only minor variations e.g. induced by the trans-
influence of the ligands.
1
I, 20.2%). NMR (CD2Cl2), H: δ 7.44–7.15 (m, 12 H, C6H4);
2.40 (s, 9 H, Me). 31P{1H}: δ 37.9 (s).
The adducts of the type (LAuI)mؒnI2 have supramolecular
structures with long I ؒ ؒ ؒ I contacts between the iodine atoms
of the components. The patterns of their island-, chain- or
layer-structures generally conform to motifs previously found
for many adducts of iodine and metal iodides as recently
summarized in a pertinent review,12b but the fascinating details
originating from steric effects and delicately balanced inter-
molecular forces are still largely unpredictable.
Iodo(trivinylphosphine)gold(I). 200 mg (0.58 mmol, 1 eq.)
(Vi3P)AuCl and 480 mg (2.9 mmol, 5 eq.) KI; 220 mg (87%
yield), mp 37–40 ЊC with decomposition (Found: C, 16.59; H,
2.13; I, 28.4. Calc. for C6H9AuIP: C, 16.53; H, 2.08; I, 29.1%).
NMR (CD2Cl2), 1H: δ 6.42–6.06 (m, ABCX-spin system).
31P{1H}: δ 27.5 (s).
Iodo[tri(2-furyl)phosphine]gold(I). 250 mg (0.54 mmol, 1 eq.)
[(2-Fur)3P]AuCl and 448 mg (2.7 mmol, 5 eq.) KI; 267 mg (89%
yield), mp 153–155 ЊC with decomposition (Found: C, 25.94; H,
1.65; I, 22.2. Calc. for C12H9AuIPO3: C, 25.92; H, 1.63; I,
22.8%). NMR (CD2Cl2), 1H: δ 7.81–6.58 (m, ABCX-spin
system). 31P{1H}: δ Ϫ20.8 (s).
Experimental
General
All experiments were routinely carried out in an atmosphere of
dry nitrogen. Solvents and glassware were dried and saturated/
filled with nitrogen. Standard equipment was used throughout.
NMR spectra were obtained at room temperature on JEOL-400
or JEOL-270 spectrometers. Chemical shifts are reported in
δ values relative to the residual solvent resonances (1H, 13C).
31P{1H} NMR spectra are referenced to external aqueous
H3PO4 (85%). The following complexes were prepared by
published methods: (MePh2P)AuCl,30 [(2-MeC6H4)3P]AuCl,36
[(3-MeC6H4)3P]AuCl,37 [(4-MeC6H4)3P]AuCl,38 (iPr3P)AuCl,39
(Vi3P)AuCl,34 [(2-Fur)3P]AuCl,40 [(2-Thi)3P]AuCl,40 [(MeO)3P]-
AuCl,41 [(PhO)3P]AuCl,42 (dppm)(AuCl)2,31 (Me3P)AuI,43
(Me2PhP)AuI,44 (Ph3P)AuI,45 (t-Bu3P)AuI.46 A sample of
(BzMePhP)AuBr3 was provided by Dr A. Bayler.
Iodo[tri(2-thienyl)phosphine]gold(I). 250 mg (0.41 mmol,
1 eq.) [(2-Thi)3P]AuCl and 350 mg (2.1 mmol, 5 eq.) KI; 220 mg
(89% yield), mp 172–173 ЊC (Found: C, 23.91; H, 1.54; I, 20.4.
Calc. for C12H9AuIPS3: C, 23.85; H, 1.50; I, 21.0%). NMR
1
(CD2Cl2), H: δ 7.81–7.23 (m, ABCX-spin system). 31P{1H}:
δ 2.6 (s).
Iodo[tri(isopropyl)phosphine]gold(I). 200 mg (0.51 mmol,
1 eq.) [iPr3P]AuCl and 415 mg (2.5 mmol, 5 eq.) KI; 209 mg
(84% yield), mp 181 ЊC with decomposition (Found: C, 22.01;
H, 4.45; I, 25.9. Calc. for C9H21AuIP: C, 22.33; H, 4.37; I,
26.2%). NMR (CD2Cl2), 1H: δ 2.38 (d/sept, JHP = 9.1 Hz, JHH
=
7.3 Hz, 3H, CH); 1.33 (d/d, JHP = 16.1 Hz, JHH = 7.3 Hz, 18 H,
Me). 31P{1H}: δ 71.1 (s).
Synthesis of (phosphine)gold(I) bromides and iodides
All syntheses were carried out in a dichloromethane/water two-
phase system. One equivalent of (phosphine)gold() chloride
was dissolved in 20 ml of dichloromethane, and five equivalents
of potassium bromide or potassium iodide, respectively, dissol-
ved in 15 ml water was added and the reaction mixture stirred
for 3 h. The aqueous phase was then separated from the organic
phase and extracted three times with 5 ml portions of CH2Cl2.
The combined organic phases were washed three times with 5
ml portions of water and dried over MgSO4. After evaporation
of the solvent in a vacuum to a volume of about 2 ml, the white
product was precipitated with about 50 ml of pentane. After
filtration and drying in vacuum the product was recrystallized
from dichloromethane/pentane.
Iodo(trimethylphosphite)gold(I). 250 mg (0.70 mmol, 1 eq.)
[(MeO)3P]AuCl and 581 mg (3.5 mmol, 5 eq.) KI; 248 mg (79%
yield), mp 55–57 ЊC with decomposition (Found: C, 8.07; H,
1.98; I, 28.1. Calc. for C3H9AuIO3P: C, 8.04; H, 2.03; I, 28.3%).
1
3
NMR (CD2Cl2), H: δ 3.83 (d, JCP = 13.9 Hz, Me). 31P{1H}:
δ 132.3 (s).
Iodo(triphenylphosphite)gold(I). 300 mg (0.55 mmol, 1 eq.)
[(PhO)3P]AuCl and 464 mg (2.8 mmol, 5 eq.) KI; 288 mg (83%
yield), mp 119 ЊC with decomposition (Found: C, 34.18; H,
2.33; I, 19.6. Calc. for C18H15AuIPO3: C, 34.09; H, 2.38; I,
20.0%). NMR (CD2Cl2), 1H: δ 7.47–7.27 (m, Ph). 31P{1H}:
δ 119.9 (s).
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(Bis(diphenylphosphino)methane)bis(bromogold(I))30. 400 mg
(0.47 mmol, 1 eq.) (dppm)(AuCl)2 and 560 mg (4.7 mmol,
10 eq.) KBr; 379 mg (86% yield), mp 274 ЊC with decom-
position (Found: C, 31.78; H, 2.40; Br, 16.6. Calc. for
C25H22Au2Br2P2: C, 32.01; H, 2.36; Br, 17.0%). NMR (CD2Cl2),
1H: δ 7.71–7.49 (m, 20 H, Ph); 3.70 (t, JHP = 11.4 Hz, 2 H, CH2).
31P{1H}: δ 26.8 (s).
Triiodo(dimethylphenylphosphine)gold(III). Following the
same procedure, using 116 mg (0.25 mmol) of (dimethyl-
phenylphosphine)iodogold() and 64 mg (0.25 mmol) of iodine
in 25 ml of dichloromethane. An equilibrium of the gold() and
gold() species was observed in solution by 31P NMR spectro-
scopy. The product was isolated as black crystals after diffusion
of n-pentane into the reaction mixture. The crystals are stable
to air and light but decompose after a few weeks even when
kept at low temperatures (Ϫ30 ЊC). 116 mg (61% yield), mp
72 ЊC with decomposition (Found: C, 13.49; H, 1.54; I, 53.3.
Calc. for C8H11AuI3P: C, 13.42; H, 1.55; I, 53.2%). NMR
(CD2Cl2), 1H: δ 7.87–7.49 (m, 5 H, Ph Au()/Au()); 2.60 (br s,
6 H, Me Au()/Au()). 31P{1H}: δ 13.8, (br s, PAu()); Ϫ10.3 (br
s, PAu()).
(Bis(diphenylphosphino)methane)bis(iodogold(I))26. 400 mg
(0.47 mmol, 1 eq.) (dppm)(AuCl)2 and 780 mg (4.7 mmol,
10 eq.) KI; 386 mg (80% yield), mp 250 ЊC (Found: C, 29.57; H,
2.26; I, 24.2. Calc. for C25H22Au2I2P2: C, 29.09; H, 2.15; I,
1
24.6%). NMR (CD2Cl2), H: δ 7.85–7.35 (m, 20 H, Ph); 3.71
(t, JHP = 11.2 Hz, 2 H, CH2). 31P{1H}: δ 28.0 (s).
Tribromo(triphenylphosphine)gold(III) (prepared by Dr. P.
Roembke). 119 mg (0.22 mmol, 1 eq.) bromo(triphenyl-
phosphine)gold() and 70 mg (0.44 mmol, 2 eq.) bromine were
reacted in 10 ml chloroform as previously published.25 Red
crystals suitable for XRD could be grown by slow diffusion
of n-pentane into the reaction mixture at Ϫ30 ЊC, 160 mg
(91% yield), mp 148 ЊC (Found: C, 30.43; H, 2.27. Calc. for
C18H15AuBr3P: C, 30.93; H, 2.16%). NMR (CDCl3), 1H: δ 7.73–
7.24 (m, Ph). 31P{1H}: δ 31.4 (s). 13C{1H}: δ 135.1 (d, JCP = 10.4
Hz); 133.3 (d, JCP = 3.1 Hz); 128.9 (d, JCP = 13.0 Hz); 125.3 (d,
JCP = 68.0 Hz).
Iodo(triphenylphosphine)gold(I)–diodine (1
: 1). 124 mg
(0.25 mmol) of iodo(triphenylphosphine)gold() and 64 mg
(0.25 mmol) of iodine were dissolved in 10 ml of dichloro-
methane at room temperature. The red–brown reaction mixture
was set aside for crystallisation by slow diffusion of n-pentane
at Ϫ30 ЊC. After several weeks red crystals were isolated. The
product is air and light stable, but decomposes at room temper-
ature within one week. It can be stored in the refrigerator
(Ϫ30 ЊC) for several months. 136 mg (65% yield), mp 110 ЊC
with decomposition (Found: C, 25.81; H, 1.89; I, 46.4. Calc. for
C18H15AuI3P: C, 25.74; H, 1.80; I, 45.3%). NMR (CD2Cl2), 1H:
δ 7.88–7.43 (m, Ph). 31P{1H}: δ 39.3 (s, PAu()).
(Bis(diphenylphosphino)methane)bromogold(I)–tribromo-
gold(III). 300 mg (0.32 mmol, 1 eq.) of (dppm)(AuBr)2 was
dissolved in 20 ml of dichloromethane and 51 mg (0.32 mmol,
1 eq.) of bromine, dissolved in 10 ml dichloromethane, was
added dropwise. After 2 h the solvent was evaporated under
reduced pressure to about 5 ml and an orange solid was precipi-
tated with 50 ml n-pentane. After recrystallisation from the
same solvents crystals suitable for XRD were obtained, 275 mg
(78% yield), mp 164 ЊC with decomposition (Found: C, 27.44;
H, 2.11; Br, 28.1. Calc. for C25H22Au2Br4P2: C, 27.35; H, 2.02;
Iodo[tri(2-tolyl)phosphine]gold(I)–diodine (2 : 1). Following
the same procedure, using 157 mg (0.25 mmol, 1 eq.) of
iodo[tri(2-tolyl)phosphine]gold() and 32 mg (0.125 mmol, 0.5
eq) of iodine. Orange crystals of [(2-Tol)3P]AuIؒ0.5I2 were
obtained in low yield after several weeks by slow diffusion of
n-pentane into the reaction mixture. The product is stable to air
and moisture but decomposes within a few weeks when kept
in the refrigerator. 66 mg (35% yield), mp 78 ЊC with
decomposition (Found: C, 33.95; H, 2.93; I, 32.4. Calc. for
C21H21AuI2P: C, 33.40; H, 2.80; I, 33.6%). NMR (CD2Cl2), 1H:
δ 7.64–6.92 (m, 12 H, C6H4); 2.69, s, 9 H, Me). 31P{1H}: δ 19.5
(s, PAu()).
1
Br, 29.1%). NMR (d6-DMSO), H: δ 7.62–7.13 (m, 20 H, Ph);
3.75 (m, 2 H, CH2). 31P{1H}: δ 25.9 (d, JPP = 20.7 Hz, PAu());
25.1 (d, JPP = 20.7 Hz, PAu()).
Reactions with iodine
Iodo[tri(isopropyl)phosphine]gold(I)–diodine (2 : 3). Following
the same procedure, using 121 mg (0.25 mmol, 1 eq.) of iodo-
[tri(isopropyl)phosphine]gold() and 95 mg (0.375 mmol, 1.5
eq) of iodine. Black crystals of [iPr3P]AuIؒ1.5 I2 were isolated
after several weeks on slow diffusion of n-pentane into the
reaction mixture. The stability of the product is similar to that
of [(2-Tol)3P]AuIؒ0.5I2. 166 mg (77% yield), mp 67 ЊC with
decomposition (Found: C, 12.34; H, 2.56; I, 57.2. Calc. for
Triiodo(trimethylphosphine)gold(III). 100 mg (0.25 mmol) of
iodo(trimethylphosphine)gold() was dissolved in 25 ml of
dichloromethane at Ϫ78 ЊC and 64 mg (0.25 mmol) of iodine
was added. After 30 min the reaction mixture was allowed to
warm slowly to room temperature. The colour of the solution
changed from dark violet to black. After 2 h the solvent was
evaporated under reduced pressure to a volume of 2 ml and
50 ml of n-pentane was added to precipitate the black product.
Crystals were obtained by slow diffusion of n-pentane vapour
into the reaction mixture in the course of several weeks. The
product is air- and light-stable but decomposes at room
temperature within a few days. It can be stored for a few months
in the refrigerator. 114 mg (70% yield), mp 115 ЊC with decom-
position (Found: C, 5.57; H, 1.30; I, 58.8. Calc. for C3H9AuI3P:
1
C9H21AuI4P: C, 12.50; H, 2.45; I, 58.7%). NMR (CD2Cl2), H:
δ 2.39 (d/sept, JHP = 9.1 Hz, JHH = 7.3 Hz, 3H, CH); 1.33 (d/d,
JHP = 16.5 Hz, JHH = 7.3 Hz, 18H, Me). 31P{1H}: δ 71.8 (s,
PAu()).
Iodo[tri(2-thienyl)phosphine]gold(I)–diodine (2 : 3). 151 mg
(0.25 mmol, 1 eq.) of iodo[tri(2-thienyl)phosphine]gold() and
95 mg (0.375 mmol, 1.5 eq) of iodine were dissolved in 15 ml of
dichloromethane, and the brown solution stirred for 2 h at
20 ЊC. Black crystals of [(2-thienyl)3P]AuIؒ1.5 I2 were obtained
by slow diffusion of n-pentane into the reaction mixture at
Ϫ30 ЊC. The stability of the compound is the same as that
of [(2-Tol)3P]AuIؒ0.5I2. 132 mg (54% yield), mp 59 ЊC with
decomposition (Found: C, 15.64; H, 1.14; I, 49.2. Calc. for
C12H9AuI4PS3: C, 14.63; H, 0.92; I, 51.5%). NMR (CD2Cl2),
1H: δ 7.73–7.21 (m, ABCX-spin system). 31P{1H}: δ 2.9 (s,
PAu()).
C, 5.51; H, 1.39; I, 58.2%). NMR (CD2Cl2), 1H: δ 2.26 (d, JHP
13.6 Hz, Me). 31P{1H}: δ Ϫ11.2 (s). 13C{1H}: δ 19.6 (d, JCP
32.7 Hz, Me).
=
=
(Triethylphosphine)triiodogold(III)22. Following the same
procedure (above), using 200 mg (0.45 mmol) of (triethyl-
phosphine)iodogold() and 115 mg (0.45 mmol) of iodine. The
product was purified by recrystallisation from dichloro-
methane–n-pentane. The black crystals decompose within a few
weeks even when kept at Ϫ30 ЊC. 248 mg (80% yield), mp 75 ЊC
with decomposition (lit.,22 77 ЊC) (Found: C, 10.13; H, 2.26; I,
53.4. Calc. for C6H15AuI3P: C, 10.36; H, 2.17; I, 54.7%). NMR
Reaction of iodo(trivinylphosphine)gold(I) with iodine. 109 mg
(0.25 mmol) of iodo(trivinylphosphine)gold() and 64 mg
(0.25 mmol) of iodine were dissolved in 15 ml of dichloro-
(CD2Cl2), 1H: δ 2.68 (m, 6H, CH2); 1.23 (d/t, JHH = 7.7 Hz, JHP
19.4 Hz, 9H, Me). 31P{1H}: δ 27.5 (s).
=
D a l t o n T r a n s . , 2 0 0 4 , 1 9 9 5 – 2 0 0 5
2002

View Article Online
Table 2 Crystal data, data collection, and structure refinement
(Me3P)AuI3
(Me2Ph P)AuI3ؒ0.75CH2Cl2
(iPr3P)AuIؒ1.5I2
(Ph3P)AuIؒI2
Crystal data
Formula
Mr
Crystal system
Space group
C3H9AuI3P
653.74
Monoclinic
P21/n
C8.75H12.50AuCl1.5I3P
779.50
Monoclinic
C2/c
C9H21AuI4P
864.79
Orthorhombic
C2221
C18H15AuI3P
839.94
Monoclinic
P21/n
a/Å
b/Å
c/Å
α/Њ
7.6198(1)
12.1910(2)
12.1256(2)
90
35.9785(4)
8.3066(1)
25.1157(4)
90
9.8516(1)
12.4681(2)
30.3821(4)
90
10.2140(1)
12.5045(1)
16.7349(2)
90
β/Њ
96.967(1)
90
1118.1(1)
3.884
116.494(1)
90
6717.7(1)
3.083
90
90
3731.9(1)
3.078
8
105.354(1)
90
2061.1(1)
2.707
γ/Њ
V/Å3
Dc/g cmϪ3
Z
4
16
4
F(000)
1120
215.16
5496
145.82
3048
145.66
1504
117.06
µ(Mo-Kα)/cmϪ1
Data collection
T /ЊC
Ϫ130
28524
2483 (0.059)
DELABS
0.390/0.774
Ϫ130
101645
7357 (0.057)
DELABS
0.348/0.787
Ϫ130
51743
3386 (0.062)
DELABS
0.553/0.863
Ϫ130
53934
4557 (0.042)
DELABS
0.465/0.826
Measured reflections
Unique reflections (Rint
Absorption correction
T min/T max
)
Refinement
Refined parameters
73
276
136
208
Final R values [I ≥ 2σ(I )]
R1
0.0323
0.0834
–
0.0336
0.0837
–
0.0156
0.0446
0.051(3)
0.539/Ϫ0.611
0.0258
0.0636
–
wR2a
Absolute structure parameter
ρfin(max./min.)/e ÅϪ3
2.864/Ϫ2.532
3.499/Ϫ3.515
1.972/Ϫ0.822
2
2
a wR2 = {[Σw(Fo2 Ϫ Fc2)2]/Σ[w(Fo )2]}1/2; w = 1/[σ2(Fo ) ϩ (ap)2 ϩ bp]; p = (Fo2 ϩ 2Fc2)/3; a = 0.0362 [(Me3P)AuI3], 0.0053 [(Me2PhP)AuI3ؒ0.75CH2Cl2],
0.0000 [(iPr3P)AuIؒ1.5I2], 0.0198 [(Ph3P)AuIؒI2]; b = 8.86 [(Me3P)AuI3], 116.68 [(Me2PhP)AuI3ؒ0.75CH2Cl2], 2.80 [(iPr3P)AuIؒ1.5I2], 5.44 [(Ph3P)-
AuIؒI2].
methane. After 1 h the solvent was removed under reduced
pressure to yield a brown oil. The NMR-spectra of the solution
indicate an equilibrium between the gold() and gold()
complexes. Neither a gold() intercalation compound nor a
Me). 31P{1H} 39.6 (s, PAu()). 4-Tolyl: NMR (CD2Cl2), 1H:
δ 7.45–7.19 (m, 12 H, C6H4); 31P{1H} 38.3 (s, PAu()).
Reaction of iodo[tri(2-furyl)phosphine]gold(I) with iodine.
Following the same procedure, using 139 mg (0.25 mmol)
of iodo[tri(2-furyl)phosphine]gold() and 64 mg (0.25 mmol) of
iodine. The NMR spectra showed no changes which would
indicate oxidation. No solid product could be isolated. NMR
(CD2Cl2), 1H: δ 7.91–6.52 (m, ABCX-spin system); 2.41 (s, 9 H,
Me). 31P{1H} Ϫ20.7 (s, PAu()).
1
gold() iodide could be isolated. NMR (CD2Cl2), H: δ 6.42–
6.06 (m, PAu()/PAu()). 31P{1H} 27.5 (br s, Au()); Ϫ12.1 (br s,
PAu()).
Reaction of iodo[tri(tert-butyl)phosphine]gold(I) with iodine.
132 mg (0.25 mmol) of iodo[tri(tert-butyl)phosphine]gold()
and 64 mg (0.25 mmol) of iodine were dissolved in 15 ml of
dichloromethane. After 1 h the solvent was removed under
reduced pressure to yield a brown liquid. In solution only the
gold() species is observed. It was not possible to crystallize a
product for further characterisation. NMR (CD2Cl2), 1H: δ 1.58
(t, 3JHP = 7.05 Hz, Me). 31P{1H} 97.5 (s, PAu()).
Reaction of iodo(trimethylphosphite)gold(I) or iodo(triphenyl-
phosphite)gold(I) with iodine. Following the same procedure,
using 115 mg (0.25 mmol) of iodo(trimethylphosphite)gold()
or 159 mg (0.25 mmol) iodo(triphenylphosphite)gold() and
64 mg (0.25 mmol) of iodine. The NMR-spectra showed that
in both cases no reaction had occurred. A crystallisation of
products was not possible. [(MeO)3P]AuI: NMR (CD2Cl2),
1H: δ 3.79 (d, JHP = 13.9 Hz, Me). 31P{1H} 132.3 (s, PAu()).
[(PhO)3P]AuI: NMR (CD2Cl2), 1H: δ 7.51–7.30 (m, Ph).
31P{1H} 119.8 (s, PAu()).
Reaction of iodo(methyldiphenylphosphine)gold(I) with iodine.
Following the same procedure, using 131 mg (0.25 mmol) of
iodo(methyldiphenylphosphine)gold() and 64 mg (0.25 mmol)
of iodine. In solution only the gold() species is observed. It was
not possible to crystallize an intercalation compound for
1
further characterisation. NMR (CD2Cl2), H: δ 7.72–7.35 (m,
Reaction of (dppm)(AuI)2 with iodine26. Following the same
procedure, 248 mg (0.25 mmol) of (dppm)(AuI)2 and 64 mg
(0.25 mmol) of iodine. The NMR analysis of the reaction
10 H, Ph); 2.13 (d, JHP = 10.7 Hz, 3 H). 31P{1H} 25.1 (s, PAu()).
Reaction of iodo[tri(3-tolyl)phosphine]gold(I) or iodo[tri-
(4-tolyl)phosphine]gold(I) with iodine. Following the same
procedure, using 157 mg (0.25 mmol) of iodo[tri(3- tolyl)phos-
phine]gold() or iodo[tri(4-tolyl)phosphine]gold(), respectively,
and 64 mg (0.25 mmol) of iodine for each reaction. In both
cases no reaction occurs and only the starting materials exist in
solution. No solid products could be crystallized. 3-Tolyl:
NMR (CD2Cl2), 1H: δ 7.60–7.11 (m, 12 H, C6H4); 2.35 (s, 9 H,
mixture showed that no oxidation of the gold centres took
1
place. NMR (CD2
Cl ), H: δ 7.87–7.39 (m, 20 H, Ph); 3.71
2
(t, JHP = 11.1 Hz, 2 H, CH2). 31P{1H}: δ 28.1 (s, PAu()).
[1,2-Bis(diphenylphosphino)benzene]diiodogold(III) triiodide.
90.6 mg (0.20 mmol, 1 eq.) of 1,2-bis(diphenylphosphino)-
benzene (dppbe) and 127 mg (0.50 mmol, 2.5 eq.) of iodine
were dissolved in 30 ml of dichloromethane. After 15 min 40 mg
D a l t o n T r a n s . , 2 0 0 4 , 1 9 9 5 – 2 0 0 5
2003

View Article Online
Table 3 Crystal data, data collection, and structure refinement
[(2-Tol)3P]AuI
[(2-Tol)3P]AuIؒ0.5I2
(dppm)(AuBr)2
(dppm)(AuI)2
Crystal data
Formula
Mr
Crystal system
Space group
a/Å
b/Å
c/Å
α/Њ
β/Њ
C21H21AuIP
628.21
Orthorhombic
Pbca
14.0151(2)
20.1112(2)
28.2688(4)
90
90
90
7967.9(2)
2.095
16
C21H21AuI2P
755.11
C25H22Au2Br2P2
938.12
Monoclinic
C/2c
22.3812(3)
7.3201(1)
18.3499(3)
90
122.226(1)
90
C25H22Au2I2P2
1032.10
Monoclinic
C2/c
22.4894(2)
7.5585(1)
18.7126(3)
90
123.579(1)
90
2650.07(6)
2.587
Triclinic
¯
P1
8.9024(1)
11.6435(2)
11.7222(2)
105.877(1)
95.169(1)
103.724(1)
1119.6(1)
2.240
γ/Њ
V/Å3
Dc/g cmϪ3
Z
2543.15(6)
2.450
4
2
4
F(000)
µ(Mo-Kα)
4704
90.15
694
94.00
1720
148.04
1864
135.21
Data collection
T /ЊC
Ϫ130
208102
8431 (0.062)
DELABS
0.526/0.852
Ϫ130
29379
4650 (0.039)
DELABS
0.386/0.788
Ϫ130
32750
2823 (0.055)
DELABS
0.488/0.836
Ϫ130
35673
2939 (0.059)
DELABS
0.323/0.754
Measured reflections
Unique reflections (Rint
Absorption correction
T min/T max
)
Refinement
Refined parameters
439
229
144
144
Final R values [I ≥ 2σ(I )]
R1
0.0330
0.0696
–
0.0254
0.0681
–
0.0311
0.0687
–
0.0260
0.0670
–
wR2a
Absolute structure parameter
ρfin(max./min.)/e ÅϪ3
3.864/Ϫ3.306
1.321/Ϫ1.772
1.348/Ϫ1.423
1.917/Ϫ1.925
a wR2 = {[Σw(Fo Ϫ Fc2)2]/Σ[w(Fo )2]}1/2; w = 1/[σ2(Fo ) ϩ (ap)2 ϩ bp]; p = (Fo ϩ 2Fc2)/3; a = 0.0254 [[(2-Tol)3P]AuI], 0.0250 [[(2-Tol)3P]AuIؒ0.5I2],
0.0319 [(dppm)(AuBr)2], 0.0249 [(dppm)(AuI)2]; b = 45.20 [[(2-Tol)3P]AuI], 1.05 [[(2-Tol)3P]AuIؒ0.5I2], 28.65 [(dppm)(AuBr)2)], 23.37 [(dppm)(AuI)2].
2
2
2
2
(0.20 mmol, 1 eq.) of gold wire was added to the solution. After
3 d of stirring the gold was completely dissolved and the colour
Acknowledgements
This work was generously supported by Deutsche Forschungs-
gemeinschaft, Volkswagenstiftung, Fonds der Chemischen
Industrie, and Heraeus GmbH. Dr A. Bayler and Dr P.
Roembke are thanked for providing crystalline samples of
(BzMePhP)AuBr3 and (Ph3P)AuBr3, and Dipl.-Chem.
of the reaction mixture had changed to black. The solvent was
evaporated under reduced pressure to a volume of about 5 ml
and the solution used for crystallisation by slow diffusion of
n-pentane. After two weeks the product was obtained as black
crystals, which are air- and moisture-stable but decompose at
room temperature after a few days. 132 mg (54% yield), mp
125 ЊC with decomposition (Found: C, 27.38; H, 1.82; I, 48.4.
Calc. for C30H24AuI5P2: C, 28.20; H, 1.89; I, 49.6%). NMR
O. Schuster for determining the structure of {[1,2-(Ph2P)2-
C6H4]AuI2}ϩI3
.
Ϫ
1
(CD2Cl2), H: δ 8.28 (m, 2H, C6H4); 7.72–7.16 (m, 20 H, Ph);
References
7.52–7.40 (m, 2H, C6H4). 31P{1H}: δ 50.2 (s). 13C{1H}: δ C6H4:
137.6 (m); 137.3 (s); 136.6 (m); Ph: 134.9 (t, JCP = 5.4 Hz); 132.9
(s); 130.5 (t, JCP = 6.9 Hz); 123.5 (d, JCP = 68.4 Hz).
1 P. Pyykkö, Chem. Rev., 1988, 88, 563.
2 (a) W. H. E. Schwarz, Fundamentals of Relativistic Effects in
Chemistry, in Theoretical Models of Chemical Bonding, ed. Z. M.
Maksic, Springer, Heidelberg, 1989, vol. 2, p. 593; (b) S.-G. Wang
and W. H. E. Schwarz, J. Am. Chem. Soc., 2004, 126, 1266.
3 (a) P. Schwerdtfeger, M. Dolg, W. H. E. Schwartz, G. A. Bowmaker
and P. D. W. Boyd, J. Chem. Phys., 1989, 91, 1762; (b)
P. Schwerdtfeger and G. A. Bowmaker, J. Chem. Phys., 1994, 100,
4487; (c) P. Schwerdtfeger, J. Am. Chem. Soc., 1989, 111, 7261.
4 (a) H. Schmidbaur, Gold. Bull., 1990, 23, 11; (b) H. Schmidbaur,
Interdisc. Sci. Rev., 1992, 17, 213; (c) H. Schmidbaur, Chem. Soc.
Rev., 1995, 24, 391.
Crystal structure determinations
Specimens of suitable quality and size were mounted on
the ends of quartz fibers in F06206R oil and used for intensity
data collection on a Nonius DIP2020 or an Enraf Nonius
CAD 4 [(BzMePhP)AuBr3] diffractometer, employing graphite-
monochromated Mo-Kα radiation. Intensity data were
corrected for absorption effects (DELABS from PLATON).
The structures were solved by a combination of direct methods
(SHELXS-97) and difference-Fourier syntheses and refined
by full matrix least-squares calculations on F 2 (SHELXL-97).
The thermal motion was treated anisotropically for all non-
hydrogen atoms. All hydrogen atoms were calculated and
allowed to ride on their parent atoms with fixed isotropic con-
tributions. Further information on crystal data, data collection
and structure refinement are summarized in Tables 2–4.
CCDC reference numbers 232528–232539.
5 H. G. Raubenheimer and S. Cronje, in Gold: Progress in Chemistry,
Biochemistry and Technology, ed. H. Schmidbaur, Wiley, Chichester.
1999, p. 557 ff.
6 M. C. Gimeno and A. Laguna, Chem. Rev., 1997, 97, 511.
7 R. J. Puddephatt, in Comprehensive Coordination Chemistry,
Pergamon, Oxford, 1987, vol. 5, p. 861.
8 M. Melnik and R. V. Parish, Coord. Chem. Rev., 1986, 70, 157.
9 M. Hargittai, A. Schulz, B. Reffy and M. Kolonits, J. Am. Chem.
Soc., 2001, 123, 1449.
10 M. Teicher and R. Weil, Phys. Rev. B, 1978, 38, 7134.
11 (a) L. I. Elding and L. H. Skibsted, Inorg. Chem., 1986, 25,
4084; (b) L. I. Elding and L. F. Olsson, Inorg. Chem., 1982, 21,
779.
See http://www.rsc.org/suppdata/dt/b4/b403005b/ for crystal-
lographic data in CIF or other electronic format.
D a l t o n T r a n s . , 2 0 0 4 , 1 9 9 5 – 2 0 0 5
2004

View Article Online
Table 4 Crystal data, data collection, and structure refinement
Ϫ
(Ph3P)AuBr3
(BzMePhP)AuBr3
(dppm)AuBr(AuBr3)ؒ2CH2Cl2
[(dppbe)AuI2]ϩI3
Crystal data
Formula
Mr
Crystal system
Space group
a/Å
b/Å
c/Å
α/Њ
C18H15AuBr3P
698.97
Monoclinic
P21
7.9533(1)
14.0747(2)
9.3338(1)
90
C14H15AuBr3P
650.93
Monoclinic
P21/c
9.573(1)
14.264(1)
12.973(1)
90
C27H26Au2Br4Cl4P2
1267.79
Monoclinic
P21/n
11.1186(1)
15.8399(1)
19.7887(2)
90
C30H24AuI5P2
1277.90
Monoclinic
P21/n
9.8050(1)
14.3361(2)
24.5570(3)
90
β/Њ
γ/Њ
112.967(1)
90
962.0(1)
2.413
104.10(1)
90
1718.1(3)
2.517
96.162(1)
90
3465.0(1)
3.078
101.442(1)
90
3383.3(1)
2.509
V/Å3
Dc/g cmϪ3
Z
2
4
4
4
F(000)
µ(Mo-Kα)
644
139.56
1192
156.17
2336
134.90
2312
90.24
Data collection
T /ЊC
Ϫ130
23415
4196 (0.057)
DELABS
0.491/0.837
Ϫ73
3943
3720 (0.036)
DIFABS
0.129/1.000
Ϫ130
85839
7114 (0.047)
DELABS
0.603/0.881
Ϫ130
76016
6208 (0.056)
DELABS
0.532/0.854
Measured reflections
Unique reflections (Rint
Absorption correction
T min/T max
)
Refinement
Refined parameters
208
172
352
343
Final R values [I ≥ 2σ(I )]
R1
0.0196
0.0510
0.022(5)
0.929/Ϫ0.732
0.0405
0.1133
–
0.0270
0.0632
–
0.0312
0.0782
–
wR2a
Absolute structure parameter
ρfin(max./min.)/e ÅϪ3
1.704/Ϫ1.727
1.064/Ϫ1.094
1.338/Ϫ1.469
2
2
a wR2 = {[Σw(Fo2 Ϫ Fc2)2]/Σ[w(Fo )2]}1/2; w = 1/[σ2(Fo ) ϩ (ap)2 ϩ bp]; p = (Fo2 ϩ 2Fc2)/3; a = 0.0000 [(Ph3P)AuBr3], 0.0814 [(BzMePhP)AuBr3], 0.0120
[(dppm)AuBr(AuBr3)ؒ2CH2Cl2], 0.0340 [[(dppbe)AuI2]ϩI3Ϫ]; b = 0.00 [(Ph3P)AuBr3], 8.25 [(BzMePhP)AuBr3], 16.34 [(dppm)AuBr(AuBr3)ؒ2CH2Cl2],
19.92 [[(dppbe)AuI2]ϩI3Ϫ].
12 (a) P. H. Svensson, J. Rosdahl and L. Kloo, Chem. Eur. J., 1999,
5, 305; (b) P. H. Svensson and L. Kloo, Chem. Rev., 2003, 103,
1649.
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