Cation and hydrogen bonding effects on the self-association and luminescence of the dicyanoaurate ion, [Au(CN)2]-

Article abstract of DOI:10.1039/b310085e

The colorless salts [C₅H₁₀NH₂] [Au^I(CN)₂], [C₄H₈NH₂] [Au^I(CN)₂], [Ph₂NNH₃][Au^I (CN)₂]·H₂O and [(n-C₃H₇)₄N][Au^I(CN)₂] ·H₂O have been prepared by evaporation of aqueous solutions of potassium dicyanoaurate and the chloride salt of the appropriate cation. Hydrogen bonding between the cations and the cyano groups of the anions facilitates the formation of structures with strong aurophilic interactions between the anions. Thus, the [Au(CN)₂]^- ions self-associate in the three salts [C₅H₁₀NH₂] [Au^I(CN)₂] (Au ... Au 3.0969(3) A), [C₄H₈NH₂][Au^I(CN)₂] (Aul ... Au2 3.0795(4) A), [Ph₂NNH₃][Au^I (CN)₂]·H₂O (Au ... Au 3.0866(4) A), while in [(n-C₃H₇)₄N][Au^I (CN)₂]·H₂O, which lacks N-H units, the gold ions are widely dispersed. The crystals of [C₅H₁₀ NH₂][Au^I(CN)₂], [C₄H₈ NH₂]-[Au^I(CN)₂] and [Ph₂ NNH₃][Au^I(CN)₂]·H₂O each show strong blue luminescence at room temperature, while [(n-C₃H₇)₄N][Au^I(CN)₂] ·H₂O is non-luminescent.

Full text of DOI:10.1039/b310085e

View Article Online / Journal Homepage / Table of Contents for this issue
Cation and hydrogen bonding effects on the self-association and
luminescence of the dicyanoaurate ion, [Au(CN)2]؊
Matthias Stender,a Marilyn M. Olmstead,a Alan L. Balch,*a Daniel Riosb and Saeed Attar*b
a Department of Chemistry, University of California Davis, California 95616, USA.
E-mail: albalch@ucdavis.edu
b Department of Chemistry, California State University Fresno, California 93740, USA.
E-mail: sattar@csufresno.edu
Received 21st August 2003, Accepted 9th September 2003
First published as an Advance Article on the web 23rd September 2003
The colorless salts [C5H10NH2][AuI(CN)2], [C4H8NH2][AuI(CN)2], [Ph2NNH3][AuI(CN)2]ؒH2O and [(n-C3H7)4N]-
[AuI(CN)2]ؒH2O have been prepared by evaporation of aqueous solutions of potassium dicyanoaurate and the
chloride salt of the appropriate cation. Hydrogen bonding between the cations and the cyano groups of the anions
facilitates the formation of structures with strong aurophilic interactions between the anions. Thus, the [Au(CN)2]Ϫ
ions self-associate in the three salts [C5H10NH2][AuI(CN)2] (Au ؒ ؒ ؒ Au 3.0969(3) Å), [C4H8NH2][AuI(CN)2]
(Au1 ؒ ؒ ؒ Au2 3.0795(4) Å), [Ph2NNH3][AuI(CN)2]ؒH2O (Au ؒ ؒ ؒ Au 3.0866(4) Å), while in [(n-C3H7)4N][AuI(CN)2]ؒ
H2O, which lacks N–H units, the gold ions are widely dispersed. The crystals of [C5H10NH2][AuI(CN)2], [C4H8NH2]-
[AuI(CN)2] and [Ph2NNH3][AuI(CN)2]ؒH2O each show strong blue luminescence at room temperature, while
[(n-C3H7)4N][AuI(CN)2]ؒH2O is non-luminescent.
less polymorph contains a linear chain of cations with a short
Au ؒ ؒ ؒ Au contact of 3.1822(3) Å, while the yellow polymorph
contains four independent cations that are organized into
kinked, infinite chains with shorter Au ؒ ؒ ؒ Au contacts of
2.9800(5), 2.9784(5), 2.9652(5) and 2.9648(5) Å. Both poly-
morphs are luminescent with λmax for the colorless form at
424 nm and λmax for the yellow form at 480 nm. However, solu-
tions of either polymorph are colorless and non-luminescent
Introduction
The high chemical stability of the dicyanoaurate ion,
[Au(CN)2]Ϫ, contributes to its many uses. Thus dicyanoaurate is
involved in the processing of gold ores,1 in the electroplating of
gold,2 as a precursor to gold–ruby glass,3 and in protein crystal-
lography as a phasing agent.4 Dicyanoaurate is a metabolite
from gold() drugs such as auranofin and allochrysine.5
Linear, two-coordinate gold() complexes are well known to
as a result of dissociation of the individual ions in solution.
undergo self-association through aurophilic attractions6,7
Since these cations readily self-associate, we wondered whether
which result from a combination of relativistic and electron
[Au(CN)2]Ϫ could be encouraged to aggregate by forming salts
correlation effects.8–10 Generally, aurophilic attractions result in
with primary and secondary amines. Such ammonium ions
could form hydrogen bonds with the nitrogen atoms of the
anion and stabilize anion self-association through a combi-
close approach of Au() centers with Au ؒ ؒ ؒ Au separations of
<3.6 Å.11,12
There have been a number of crystallographic studies of
nation of hydrogen bonding and other coulombic interactions.
compounds containing [Au(CN)2]Ϫ. Recently, however, in
Here we report that close approach of [Au(CN)2]Ϫ ions can be
reviewing the available crystal structures of materials con-
achieved in this fashion.
taining [Au(CN)2]Ϫ, Schmidbaur and co-workers noted that
anion aggregation occurred only in “very special cases”.13 The
majority of the known structures showed the linear [Au(CN)2]Ϫ
Results
unit surrounded by cations. Aggregation of the linear [Au-
(CN)2]Ϫ would appear to be disfavored on coulombic grounds,
but the simple linear structure itself would seem to encourage
self-association through aurophilic interactions.
The colorless salts, [C5H10NH2][AuI(CN)2], [C4H8NH2]-
[AuI(CN)2], [Ph2NNH3][AuI(CN)2] and [(n-C3H7)4N][AuI(CN)2]
have been obtained by mixing aqueous solutions of potassium
dicyanoaurate with aqueous or methanolic solutions con-
taining the appropriate cation and allowing these solutions to
slowly evaporate.
Several studies by Patterson and co-workers have shown that
[Au(CN)2]Ϫ aggregates under a variety of conditions in both the
solid state and in solution.14–16 The aggregated forms display
variations in their luminescence. For example, the luminescence
from solutions of K[Au(CN)2] can be “tuned” so that λmax
varies from 275 to 470 nm depending upon the concentration
and solvent.17 The resulting luminescence has been attributed to
excited state interactions in oligomeric forms of this anion.14–17
For a simple dimer, the orbitals involved are an antibonding
The structure of [C5H10NH2][AuI(CN)2]
The asymmetric unit consists of one anion and one cation in
general positions. Selected interatomic distances and angles are
given in Table 1 for all of the new compounds reported here.
The dimensions of the anion and cation with its chair conform-
ation are normal. As seen in Fig. 1, the anions are arranged into
columns with a remarkably short Au ؒ ؒ ؒ Au distance of
3.0969(3) Å. The extended chains of anions are slightly bent
with an Au ؒ ؒ ؒ Au ؒ ؒ ؒ Au angle of 165.108(7)Њ. Adjacent
[AuI(CN)2]Ϫ ions have a nearly staggered orientation with a
C1–Au1 ؒ ؒ ؒ Au1B–C1B dihedral angle of 64.8Њ.
2
HOMO with largely dz character and a bonding LUMO with
largely pz character, where the z axis connects adjacent gold
centers. Because of the unusual combination of a antibonding
HOMO and a bonding LUMO, the Au ؒ ؒ ؒ Au attraction is
stronger in the excited state than in the ground state.
Recent studies of the gold() complexes, [(CyNC)2AuI]ϩ and
[Au{C(NHMe)2}2]ϩ, have shown that these cations can undergo
significant self-association in the solid state and that this aggre-
gation is dependent on the chemical identity of the anions
involved.18–20 For example [(CyNC)2AuI]ϩ in [(CyNC)2AuI](PF6)
self-associates to form two crystalline polymorphs. The color-
Cations are situated between the chains of anions, and the
amino protons are hydrogen bonded to the cyano groups of
anions in adjacent chains as seen in Fig. 1. Fig. 2 shows the unit
cell and the parallel arrangements of the chains.
D a l t o n T r a n s . , 2 0 0 3 , 4 2 8 2 – 4 2 8 7
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 3
4282

View Article Online
Table 1 Selected bond lengths (Å) and bond angles (Њ) for [AuI(CN)2]Ϫ salts
[C5H10NH2] [AuI(CN)2]
[C4H8NH2] [AuI(CN)2]
[Ph2NNH3][AuI(CN)2]ؒH2O
[n-Pr4N] [AuI(CN)2]ؒH2O
Au1–C1
Au1–C2
C1–N1
C2–N2
1.987(3)
1.994(2)
1.147(4)
1.144(4)
1.988(5)
1.147(6)
1.986(4)
1.985(4)
1.143(5)
1.150(5)
1.989(4)
1.139(5)
C–Au–C
179.28(11)
178.1(3)
177.78(16)
180
Fig. 1 A view of a portion of the structure of [C5H10NH2][AuI(CN)2]
that shows the columns of [AuI(CN)2]Ϫ ions and the hydrogen bonding
interaction between the cations and anions. Selected interatomic
distances (Å): Au1 ؒ ؒ ؒ Au1B 3.0969(3), N3H1 ؒ ؒ ؒ N1 1.94, N3 ؒ ؒ ؒ N1
2.849(3), N3H2 ؒ ؒ ؒ N2 1.92, N3 ؒ ؒ ؒ N2 2.824(3). Selected interatomic
angles (Њ): Au1 ؒ ؒ ؒ Au1B ؒ ؒ ؒ Au1C 165.108(7), N3 ؒ ؒ ؒ H1 ؒ ؒ ؒ N1
170.1, N3 ؒ ؒ ؒ H1 ؒ ؒ ؒ N1 167.1.
Fig. 3 A view of the structure of [C4H8NH2][AuI(CN)2] that shows the
chains of [AuI(CN)2]Ϫ ions, the hydrogen bonding interaction between
one cation and one anion, and the disorder in the pyrrolidinium ring.
Selected interatomic distances (Å): Au1 ؒ ؒ ؒ Au2 3.0795(4), N3 ؒ ؒ ؒ N2
2.851(6). Selected interatomic angles (Њ): Au2 ؒ ؒ ؒ Au1 ؒ ؒ ؒ Au2A
147.100(9), Au1 ؒ ؒ ؒ Au2 ؒ ؒ ؒ Au1B 180.000(8).
Au2 ؒ ؒ ؒ Au1 ؒ ؒ ؒ Au2 part is bent at an angle of 147.100(9)Њ.
The C1–Au1 ؒ ؒ ؒ Au12–C12 dihedral angle is 54.9Њ and the
neighboring anions are nearly staggered. As seen in Fig. 3, there
is disorder that involves one carbon of the pyrrolidinium ring
and consequently the ring conformation.
As is the case with [C5H10NH2][AuI(CN)2], the cations are
hydrogen-bonded to the nitrogen atoms of the anions. Again
each cation spans two adjacent chains. However, the structural
motif formed by this interaction is more complex in [C4H8-
NH2][AuI(CN)2] than in [C5H10NH2][AuI(CN)2]. As seen in the
stereoview in Fig. 4, a chain of anions in [C4H8NH2][AuI(CN)2]
is connected to four other similar chains through hydrogen
bonding to the cations.
Fig. 2 A view of the unit cell of [C5H10NH2][AuI(CN)2] that shows the
interactions between cations and anions. The interactions are shown
as bold dashed lines and the hydrogen bonds as thin dashed lines.
The structure of [C4H8NH2][AuI(CN)2]
Selected interatomic distances and angles are given in Table 1.
The asymmetric unit consists of two half-anions in special
positions and one cation in a general position. Fig. 3 shows a
drawing of the chain of anions and the location of one cation
which forms a hydrogen bond to an anion. Au1 is situated
on a crystallographic center of symmetry while Au2 is located
on a crystallographic two-fold axis. The two different anions
form a single chain connected by aurophilic interactions
with an Au1 ؒ ؒ ؒ Au2 distance of 3.0795(4) Å. Within these
chains the Au1 ؒ ؒ ؒ Au2 ؒ ؒ ؒ Au1 portion is linear while the
Fig. 4 A stereoview of the structure of [C4H8NH2][AuI(CN)2] that
shows five chains of [AuI(CN)2]Ϫ ions and the way the cations form
hydrogen bond between the chains. In this drawing the Au ؒ ؒ ؒ Au
interactions are shown as solid lines.
The structure of [Ph2NNH3][AuI(CN)2]ؒH2O
There are one cation, one anion, and one water molecule in the
asymmetric unit. These components are interconnected through
a combination of aurophilic attractions and hydrogen bonds as
D a l t o n T r a n s . , 2 0 0 3 , 4 2 8 2 – 4 2 8 7
4283

View Article Online
Fig. 5 A view of the structure of [Ph2NNH3][AuI(CN)2]ؒH2O that
shows two chains of [AuI(CN)2]Ϫ ions and the hydrogen bonding
interactions that run parallel to these chain. Selected interatomic
distances (Å): Au1 ؒ ؒ ؒ Au1A 3.0866(4), N4H4A ؒ ؒ ؒ N2C 1.96
N4 ؒ ؒ ؒ N2C 2.864(4), N4 ؒ ؒ ؒ N1B 2.859(4), N4 ؒ ؒ ؒ O1 2.788(4),
N1A ؒ ؒ ؒ O1 2.913(4), N2D ؒ ؒ ؒ O1 2.925(4). Selected interatomic
angle (Њ): Au1A ؒ ؒ ؒ Au1 ؒ ؒ ؒ Au1B 175.635(9).
Fig. 7 A view of the structure of [n-Pr4N][AuI(CN)2]ؒH2O that shows
the interactions between the [AuI(CN)2]Ϫ ions and the water molecules.
Selected interatomic distances (Å): Au1 ؒ ؒ ؒ Au1#1 7.526(1), N1 ؒ ؒ ؒ O1
2.920(4).
seen in Fig. 5. The aurophilic attractions produce a column of
anions with a Au ؒ ؒ ؒ Au separation of 3.0866(4) Å. The chain
is slightly bent at each gold ion with an Au ؒ ؒ ؒ Au ؒ ؒ ؒ Au angle
of 175.635(9)Њ. Within the column the anions are staggered
with a dihedral C1–Au1–Au1Ј–C1Ј angle of 55.3Њ.
One of the N–H protons of the cation is hydrogen bonded to
N1 of the anion, while another is hydrogen bonded to a water
molecule. The water molecule in turn is hydrogen bonded to a
nitrogen atom of another anion. These interactions produce
a pattern of alternating cations and water molecules that runs
parallel to the chain of anions and interacts with that chain
through hydrogen bonds to the nitrogen atoms of every other
anion as seen in Fig. 5. Fig. 6 shows a packing diagram for a
larger portion of the solid and reveals how the units shown in
Fig. 5 are put together. Each column of anions make hydrogen
bonding contacts with four rows of alternating [Ph2NNH3]ϩ
ions and water molecules. In this fashion sheets of cations,
water molecules and anions are created that run parallel to the
crystallographic ab plane. These sheets interact with one ano-
ther through van der Waals interactions between the phenyl
rings of the cations. Note that the phenyl rings protrude on
either side of the sheets.
Fig.
8
A
drawing of [n-Pr4N][AuI(CN)2]ؒH2O which shows the
layering of the anions and their hydrogen bonded water molecules and
the cation.
are interleaved in the crystal. The cations lie in spaces between
the anions and water molecules which run diagonally along
the unit cell. The closest contact between gold ions in different
zigzag arrays is 8.1387(12) Å, the length of the crystallographic
b axis.
Luminescence
Colorless crystals of [C5H10NH2][AuI(CN)2], [C4H8NH2]-
[AuI(CN)2] and [Ph2NNH3][AuI(CN)2]ؒH2O show intense blue
photoluminescence at room temperature. The emission and
excitation spectra of [C5H10NH2][AuI(CN)2] at 298 K are shown
in Fig. 9. There is a strong, broad emission with a maximum at
436 nm. The excitation profile shows a maximum at 378 nm
with a shoulder at 292 nm. The emission spectrum does not
change when the excitation wavelength is altered.
Fig. 6 A view of the unit cell of [[Ph2NNH3][AuI(CN)2]ؒH2O that
As seen in Fig. 10, the luminescence from [C4H8NH2]-
[AuI(CN)2] is similar. At 298 K, the emission spectrum con-
sists of a broad, symmetrical band with λmax of 451 nm. The
excitation profile shows maxima at 405, 385, 360 and 328 nm,
but excitation at each of these wavelengths produces the same
emission spectrum as that shown in Fig. 10.
shows the interactions between cations, anions and water molecules.
The structure of [(n-C3H7)4N][AuI(CN)2]ؒH2O
The asymmetric unit consists of one half of a cation, one half
of an anion and one half of a water molecule. The gold ion
is positioned at a center of symmetry while the nitrogen and
oxygen atoms are located on two-fold axes. A view of the struc-
ture is shown in Fig. 7. A water molecule is hydrogen bonded to
the nitrogen atoms of two anions to form an extended zig-zag
array of these units. As a consequence, the gold ions are widely
separated. The shortest distance between gold ions in this array
is 7.526(1) Å. Fig. 8 shows how the components shown in Fig. 7
Crystals of [Ph2NNH3][AuI(CN)2]ؒH2O show
a broad
emission at 400 nm with an excitation maximum at 350 nm.
Crystalline [(n-C3H7)4N][AuI(CN)2]ؒH2O with its widely
separated gold centers is non-luminescent at room temperature
and at 77 K. Likewise, we have observed that [(n-C4H9)4N]-
[AuI(CN)2], which also has widely dispersed anions with long
distances between gold ions,21 is non-luminescent.
D a l t o n T r a n s . , 2 0 0 3 , 4 2 8 2 – 4 2 8 7
4284

View Article Online
are shorter than the comparable distances between cations in
the white polymorph of [(CyNC)2AuI](PF6) (3.1822(3) Å) but
longer than those in its yellow polymorph (2.9800(5), 2.9784(5),
2.9652(5), 2.9648(5) Å).18 Similarly the Au ؒ ؒ ؒ Au distances
between cations in [Au{C(NHMe)2}2](PF6)ؒ0.5Me2CO,
(3.1882(1) Å) and in [Au{C(NHMe)2}2](BF4) (3.4615(2) Å)19
are longer than those Au ؒ ؒ ؒ Au distances seen in the ammo-
nium salts reported here.
It is also informative to compare the Au ؒ ؒ ؒ Au distances in
the above mentioned chains of anions and cation to those in the
series of neutral molecules (RNC)AuICN. The Au ؒ ؒ ؒ Au
interactions between these linear molecules create supra-
molecular structures that fall into three classes with increasing
numbers of contacts between gold centers: simple chains, side-
by-side chains, and nets.29 Those with the simple chains struc-
tures are the most relevant for our comparisons. Thus, the
structures of (CyNC)AuICN and (t-BuNC)AuICN consist of
corrugated chains of the individual molecules which pack
about centers of symmetry so that their dipoles are aligned
head-to-tail as shown as A in Scheme 1.25,30 In (CyNC)AuICN
there are two alternating Au ؒ ؒ ؒ Au distances of 3.426(3)
and 3.442(3) Å, while in (t-BuNC)AuICN there is only one
Au ؒ ؒ ؒ Au distance, 3.568 Å.26 These distances are considerably
longer than those seen for the chains of cations and anions
discussed above and appear to indicate that dipolar forces
weaken the aurophilic attractions in (RNC)AuICN. With pairs
of these rod-like molecules the dihedral angles between the two
can vary from the fully eclipsed, shown as B in Scheme 1, to the
fully staggered shown as C . The staggered orientation C is the
one usually found for the shortest Au ؒ ؒ ؒ Au separations and
favors aurophilic attractions, while the eclipsed orientation B
places the dipoles of the adjacent molecules in proper juxta-
position. For the symmetrical cationic and anionic gold
complexes discussed above, these is no dipole contribution to
consider, and thus a staggered orientation C is present and
results in the shorter Au ؒ ؒ ؒ Au separations. For (RNC)AuICN
the dipolar interaction produces the eclipsed orientation B
and the Au ؒ ؒ ؒ Au distances are longer. Similarly in the series
of neutral, polar molecules, (RNC)AuIX with X = Cl, Br or I,
dipolar factors dominate the situation to the extent that the
Fig. 9 Emission and excitation spectra of crystalline [C5H10NH2]-
[AuI(CN)2] at 298 K.
Fig. 10 Emission and excitation spectra of crystalline [C4H8NH2]-
[AuI(CN)2] at 298 K.
Discussion
The results reported here show that close contact between
[Au(CN)2]Ϫ ions can be promoted through the use of ammo-
nium ions whose H–N–H units form hydrogen bonds to the
anions. These hydrogen bonds insure close proximity of
the cations to the anions and help to minimize the coulombic
repulsion between the anions. These observations support the
conclusions of Schmidbaur and co-workers that additional
support in the form of contacts with cations or solvent
molecules is needed to promote aurophilic interactions between
[Au(CN)2]Ϫ ions.13 One other case of a protonated amine
facilitating the formation of a chain of [Au(CN)2]Ϫ ions has
31
Au ؒ ؒ ؒ Au separations are weak to non-existent Complexes
of the type (RNC)AuIX form isostructural crystals in which
corrugated chains of type A are present. Within these chains
the Au ؒ ؒ ؒ Au separations alternate so that with X = Cl the
distances are 3.3894(7) and 3.5816(7) Å, but with X = I they
increase to 3.7182(11) and 3.9304(12) Å, distances which are
well outside the range where aurophilic attractions are signifi-
cant.30 Theoretical calculations on RNC)AuIX indicate that the
aurophilic attraction between such molecules is weak.32
been reported.22 In (2-methylimidazolinium)[Au(CN)2]
a
staggered chain of these anions is present with an Au ؒ ؒ ؒ Au
distance of 3.25 Å.22 The chains of [Au(CN)2]Ϫ ions that are
reported here have rather short Au ؒ ؒ ؒ Au contacts that span a
narrow range of 3.0795(4)–3.0969(3) Å. For comparison, in
[Pt(NH3)4][Au(CN)2]ؒ1.5(H2O), which contains a chains of
Au–Pt–Au units that intersect via Au ؒ ؒ ؒ Au contacts, there are
three such contacts between [Au(CN)2]Ϫ ions with distances of
3.3307(5), 3.2902(5) and 3.1903(4) Å.23 All of these distances
are longer than those seen in the ammonium salts reported
here. In related work, Leznoff and co-workers have shown that
chains of [Au(CN)2]Ϫ ions can also be formed by reacting this
anion with cationic transition metal complexes.24–27 Poly-
pyridinium cations have been found to produce crystalline
materials that contain [Au(CN)2]Ϫ ions which aggregate to form
trimers, tetramers, or chains.28
The luminescent properties of gold() complexes has attracted
a considerable amount of attention.33,34 The luminescence
observed for crystalline samples of [C5H10NH2][AuI(CN)2]
and [C4H8NH2][AuI(CN)2] can be attributed to the presence
of aurophilic attractions which have produced the chains
of staggered anions in these solids. In contrast, crystals of
[(n-C3H7)4N][AuI(CN)2]ؒH2O and [(n-C4H9)4N][AuI(CN)2],
which have widely separated gold centers, are non-luminescent
under similar conditions. These observations are entirely con-
sistent with the studies of Patterson and co-workers who have
The Au ؒ ؒ ؒ Au distances in the chains of [Au(CN)2]Ϫ anions
Scheme 1
D a l t o n T r a n s . , 2 0 0 3 , 4 2 8 2 – 4 2 8 7
4285

View Article Online
Table 2 Crystal data and data collection parameters for [AuI(CN)2]Ϫ salts
[n-Pr4N][AuI(CN)2]ؒ
H2O
[C5H10NH2][AuI(CN)2]
[C4H8NH2][AuI(CN)2]
[Ph2NNH3][AuI(CN)2]ؒH2O
Formula
Mr
Color and habit
Crystal system
C7H12AuN3
335.16
Colorless block
Orthorhombic
Pbca
C6H10AuN3
321.14
Colorless needle
Monoclinic
C2/c
C14H15AuN4O
452.27
Colorless needle
Orthorhombic
Pbca
C14H30AuN3O
453.38
Colorless block
Monoclinic
P2/n
Space group
a/Å
b/Å
c/Å
α/Њ
15.8490(17)
6.1415(7)
19.742(2)
90
20.215(3)
8.5264(11)
11.8138(15)
90
19.765(2)
6.1688(8)
24.757(3)
90
8.3442(12)
8.1387(12)
13.351(2)
90
β/Њ
90
90
1921.6(4)
90(2)
121.927(2)
90
1728.2(4)
190(2)
90
90
3018.5(6)
90(2)
95.497(2)
90
902.5(2)
130(2)
γ/Њ
V/Å3
T/K
Z
8
8
8
2
Dc/g cmϪ3
2.317
2.468
1.990
1.668
λ(Mo-Kα)/Å
0.71073
15.257
0.17–42
3021
101
0.017
0.71073
16.958
0.26–0.63
2690
110
0.024
0.71073
9.748
0.19–0.64
4588
179
0.024
0.71073
8.148
0.44–59
2799
92
0.022
µ/mmϪ1
Range of transm. factors
No. unique data
No. parameters refined
Ra
wR2b
0.037
0.053
0.053
0.051
a R1 = Σ||Fo| Ϫ |Fc||/Σ|Fo| (obs. data, I > 2σ(I )). b wR2 = [Σ[w(Fo2 Ϫ Fc2)2]/Σ[w(Fo )2]]1/2 (all data).
2
attributed the remarkable variations in the luminescence
resulting from [AuI(CN)2]Ϫ in different environments to the
formation of various aggregates.14–17 The similarities between
the emission spectra of [C5H10NH2][AuI(CN)2] and [C4H8NH2]-
[AuI(CN)2] (Figs. 9 and 10, respectively) reflect the fact that
both have nearly staggered chain structures with rather similar
Au ؒ ؒ ؒ Au separations.
Preparation of [Ph2NNH3][AuI(CN)2]ؒH2O
A solution of 53.1 mg (0.18 mmol) of potassium dicyanoaurate
in 2 mL of water was added under stirring to a solution of
40.3 mg (0.18 mmol) diphenylhydrazinium hydrochloride in
2 mL of methanol. The reaction mixture was filtered and after
slow evaporation of the solvent, crystals suitable for X-ray
analysis were formed after 24 h. After removing the mother-
liquor with a pipette, the crystals were washed with cold diethyl
ether and dried in air. The yield was 57.7 mg (0.13 mmol; 72%).
The product is slightly soluble in water and methanol. IR
Experimental
spectrum: ν(CN) 2149, 2138 cmϪ1
.
Samples of pyrrolidinium hydrochloride and piperidinium
hydrochloride were obtained by adding stoichiometric amounts
of the appropriate amine to an aqueous solution of hydro-
chloric acid. The solution was allowed to evaporate over a week
period, after which the colorless crystalline product was
collected.
Preparation of [n-Pr4N][AuI(CN)2]ؒH2O
A solution of 70.8 mg (0.24 mmol) of potassium dicyanoaurate
in 2 mL of water was added under stirring to a solution of
66.5 mg (0.25 mmol) tetra(n-propyl)ammonium bromide in
2 mL of water and 1 mL of methanol. The reaction mixture was
filtered. After slow evaporation of the solvent, crystals suitable
for X-ray analysis formed in 3 days. After removal of the
mother liquor with a pipette, the crystals were washed with
ethanol and diethyl ether and dried in air. The yield was 63.4 mg
(0.14 mmol; 60%). The product is soluble in acetonitrile.
Preparation of [C5H10NH2][AuI(CN)2]
A solution of 50 mg (0.17 mmol) of potassium dicyanoaurate
in 2 mL of water was added dropwise to a solution of 18.6 mg
(0.17 mmol) pyrrolidinium hydrochloride in 2 mL of water. The
yellow reaction mixture was filtered and after 3 days of slow
evaporation of the solvent, colorless crystals of the product
that were suitable for X-ray analysis were formed and removed
from the mother-liquor. The yield was 40.1 mg (72%). The
product is soluble in water and methanol and slightly soluble in
acetonitrile. On heating to 250 ЊC this salt slowly turns brown
but does not melt. IR spectrum: 3448br, 2968s, 2813m, 2553m,
Physical measurements
IR spectra were recorded as pressed KBr pellets on a Matteson
Galaxie Series FTIR 3000 spectrometer. Electronic absorption
spectra were recorded using a Hewlett-Packard 8450A diode
array spectrophotometer. Conventional fluorescence excitation
and emission spectra were recorded on a Perkin Elmer LS50B
luminescence spectrophotometer.
2458w, 2148vs (ν(CN)), 1627m, 1464w cmϪ1
.
Preparation of [C4H8NH2][AuI(CN)2]
A solution of 50 mg (0.17 mmol) of potassium dicyanoaurate
in 2 mL of water was added dropwise to a solution of 21.0 mg
(0.17 mmol) of piperidinium hydrochloride in 2 mL of water.
The yellow reaction mixture was filtered. After 4 days of slow
evaporation of the solvent, crystals of the product that were
suitable for X-ray crystallography were formed. The mother-
liquor was removed to produce colorless crystals: 38.2 mg
(65%). The product has good solubility in water and methanol.
This compound does not melt below 250 ЊC but does darken
during heating. IR spectrum: 3437br, 3008s, 2767m, 2143vs
X-Ray crystallography and data collection
The crystals were removed from the glass tubes in which they
were grown together with a small amount of mother-liquor
and immediately coated with a hydrocarbon oil on the micro-
scope slide. Suitable crystals were mounted on glass fibers with
silicone grease and placed in the cold dinitrogen stream of a
Bruker SMART CCD with graphite-monochromated Mo-Kα
radiation at 90(2) K. No decay was observed in 50 duplicate
frames at the end of each data collection. Crystal data are given
in Table 2.
(ν(CN)), 1639w, 1402m cmϪ1
.
D a l t o n T r a n s . , 2 0 0 3 , 4 2 8 2 – 4 2 8 7
4286

View Article Online
14 M. A. Rawashdeh-Omary, M. A. Omary and H. H. Patterson,
The structures were solved by direct methods and refined
using all data (based on F 2) using the software of SHELXTL
J. Am. Chem. Soc., 2000, 122, 10371.
15 M. A. Rawashdeh-Omary, M. A. Omary, G. E. Shankle and
H. H. Patterson, J. Phys. Chem. B, 2000, 104, 6143.
16 M. A. Omary and H. H. Patterson, J. Am. Chem. Soc., 1998, 120,
7696.
5.1.
A semiempirical method utilizing equivalents was
employed to correct for absorption.35 Hydrogen atoms were
added geometrically and refined with a riding model.
CCDC reference numbers 218034–218037.
17 M. A. Rawashdeh-Omary, M. A. Omary, H. H. Patterson and
J. P. Fackler, Jr., J. Am. Chem. Soc., 2001, 123, 11237.
18 R. L. White-Morris, M. M. Olmstead and A. L. Balch, J. Am. Chem.
Soc., 2003, 125, 1003.
See http://www.rsc.org/suppdata/dt/b3/b310085e/ for crystal-
lographic data in CIF or other electronic format.
19 R. L. White-Morris, M. M. Olmstead, F. Jiang, D. S. Tinti and
A. L. Balch, J. Am. Chem. Soc., 2002, 124, 2327.
20 R. L. White-Morris, M. M. Olmstead, F. Jiang and A. L. Balch,
Inorg. Chem., 2002, 41, 2313.
21 R. J. Schubert and K.-J. Range, Z. Naturforsch., Teil B., 1990, 1118.
22 A. H. Schwellnus, L. Denner and J. C. A. Boeyens, Polyhedron, 1990,
9, 975.
Acknowledgements
We thank the Petroleum Research Fund (Grant 37056-AC) for
support. The Bruker SMART 1000 diffractometer was funded
in part by NSF Instrumentation grant CHE-9808259.
23 M. Stender, R. L. White-Morris, M. M. Olmstead and A. L. Balch,
Inorg. Chem., 2003, 42, 4504.
24 C. J. Shorrock, B.-Y. Xue, P. B. Kim, R. J. Batchelor, B. O. Patrick
and D. B. Leznoff, Inorg. Chem., 2002, 41, 6743.
25 D. B. Leznoff, B.-Y. Xue, R. J. Batchelor, F. W. B. Einstein and
B. O. Patrick, Inorg. Chem., 2001, 40, 6026.
References
1 M. D. Adams, M. W. Johns and D. W. Dew, in Gold; Progress in
Chemistry, Biochemistry and Technology, ed. H. Schmidbaur, John
Wiley and Sons, New York, 1999, p. 65.
2 R. J. Puddephatt, in Gold; Progress in Chemistry, Biochemistry and
Technology, ed. H. Schmidbaur, John Wiley and Sons, New York,
1999, p. 235.
3 F. E. Wagner, S. Haslbeck, L. Stievano, S. Calogero, Q. A. Pankhurst
and K.-P. Martlinek, Nature (London), 2000, 407, 691.
4 T. J. Boggon and L. Shapiro, Structure, 2000, 8, R143.
5 F. S. Shaw, III, Chem. Rev., 1999, 99, 2589.
6 H. Schmidbaur, Chem. Soc. Rev., 1995, 24, 391.
7 H. Schmidbaur, Interdisiplinary Sci. Rev., 1992, 17, 213.
8 P. Pyykkö, Chem. Rev, 1997, 97, 597.
26 D. B. Leznoff, B.-Y. Xue, B. O. Patrick, V. Sanchez and
R. C. Thompson, Chem. Commun., 2001, 259.
27 D. B. Leznoff, B.-Y. Xue, C. L. Stevens, A. Storr, R. C. Thompson
and B. O. Patrick, Polyhedron, 2001, 20, 1247.
28 R. E. Cramer, D. W. Smith and W. VanDoorne, Inorg. Chem, 1998,
37, 5895.
29 R. L. White-Morris, M. Stender, D. S. Tinti, A. L. Balch, D. Rios
and S. Attar, Inorg. Chem, 2003, 42, 3237.
30 C.-M. Che, H.-K. Yip, W.-T. Wong and T.-F. Lai, Inorg. Chim. Acta,
1992, 197, 177.
9 P. Pyykkö, N. Runeberg and F. Mendizabal, Chem. Euro. J., 1997,
3, 1451.
10 P. Pyykkö and F. Mendizabal, Chem. Eur. J., 1997, 3, 1458.
11 P. G. Jones, Gold Bull., 1986, 19, 46; P. G. Jones, Gold Bull., 1983, 16,
114; P. G. Jones, Gold Bull., 1981, 14, 159; P. G. Jones, Gold Bull.,
1981, 14, 102.
12 S. S. Pathaneni and G. R. Desiraju, J. Chem. Soc., Dalton Trans.,
1993, 319.
13 R.-Y. Liau, H. Ehlich, A. Schier and H. Schmidbaur,
Z. Naturforsch., Teil B, 2002, 57, 1085.
31 R. L. White-Morris, M. M. Olmstead, A. L. Balch, O. Elbjeirami
and M. A. Omary, Inorg. Chem., in press.
32 R.-Y. Liau, T. Mathieson, A. Schier, R. J. Berger, N. Runeberg and
H. Schmidbaur, Z. Naturforsch., Teil B, 2002, 57, 881.
33 J. M. Forward, J. P. Fackler, Jr. and Z. Assefa, in Optoelectronic
Properties of Inorganic Compounds, ed. D. M. Roundhill and
J. P. Fackler, Jr, Plenum Press, New York, 1999, p. 195.
34 V. W. W. Yam and K. K. W. Lo, Chem. Soc. Rev., 1999, 28, 323.
35 SADABS 2.0: G. M. Sheldrick, based on
a method of
R. H. Blessing, Acta Crystallogr., Sect. A, 1995, 51, 33.
D a l t o n T r a n s . , 2 0 0 3 , 4 2 8 2 – 4 2 8 7
4287