Halogen impact into new oxonium benzo-crown ether complexes with tetrachloro- and tetrabromoaurates(iii)

Article abstract of DOI:10.1039/c4dt00017j

Five oxonium tetrahalogenaurate(iii) (Hal = Cl, Br) benzo-crown ether (BCE) complexes are prepared and reported. The new compounds are [(H ₃O)(B18C6)_0.58(4′-Cl-B18C6)_0.42] [AuCl₄] 1, [(H₃O)(B18C6)][Au

Full text of DOI:10.1039/c4dt00017j

Dalton
Transactions
View Article Online
View Journal
PAPER
Halogen impact into new oxonium benzo-crown
ether complexes with tetrachloro- and
tetrabromoaurates(III)†
Cite this: DOI: 10.1039/c4dt00017j
Sergei M. Pluzhnik-Gladyr,a Victor Ch. Kravtsov,b Marina S. Fonari*b and
Gerbert L. Kamalova
Five oxonium tetrahalogenaurate(III) (Hal = Cl, Br) benzo-crown ether (BCE) complexes are prepared and
reported. The new compounds are [(H3O)(B18C6)0.58(4’-Cl-B18C6)0.42][AuCl4] 1, [(H3O)(B18C6)][AuCl4] 2,
[(H3O)(4’-Br-B18C6)][AuCl4] 3, [(H3O)(4’-Br-B18C6)][AuBr4] 4, and [(H3O)(B18C6)][AuBr4] 5. The reaction
medium, distinctive from the previously used aqua regia, allowed avoiding the unwanted nitration of initial
macrocycles. The compositions and structures for 1, 3, 4, and 5 were proved by single crystal X-ray crys-
tallography. The complete conversion of tetrachloroaurate(III) to the tetrabromoaurate(III) salts resulted in
complex 4 isomorphous and isostructural to 3. All compounds form the laminated structures with alter-
nation of cationic and anionic layers. The robustness of the anionic sheets is sustained by the halogen–
halogen interactions and makes crucial impact on extraction of stoichiometric products in the case of
tetrabromoaurate(III) salts.
Received 3rd January 2014,
Accepted 12th February 2014
DOI: 10.1039/c4dt00017j
www.rsc.org/dalton
To date, CEs are widely used for the selective extraction,
reduction and subsequent isolation of various metals from
Introduction
Since their discovery in 19671,2 crown ethers (CEs) attract per-
sistent attention as synthetic models in host–guest chemistry
and building blocks for a broad range of modern materials.3,4
The specific binding of cationic species is the most intriguing
feature of these macrocyclic molecules. The binding selectivity
to a great extent is dictated by the match between the cationic
guest and the cyclic ether framework capable to optimize the
interaction of its electron donor oxygen sites with the cation.5
As far as the extraction ability of the CEs is defined primarily
by spacious restrictions, their complexing properties can be
controlled by varying their molecular structures. One of the
factors that directly affects the binding affinity is the confor-
mational flexibility of the CE’s ring that in its turn depends on
the ring size, the substituents, and nature of the donor
centers. The CEs, having been initially elaborated for trapping
the divalent metals, also proved themselves as excellent hosts
for singly charged alkali metal cations,4,5 small molecular
cations, such as oxonium, ammonium and protonated
amines,6 as well as for multiply charged guest species.7
the acidic media.8 The property of CEs to form in the
solid state stable complexes with hydrochloride, hydro-
bromide, and hydroselenium hexabromide has been
documented.9–11 All products are of the “host–guest” type
varying by the degree of oxonium hydration. Recently we have
reported the oxonium-containing Zr(IV), Hf(IV), Ta(V), and Nb(V)
fluoro- and oxofluorometalate macrocyclic crystalline solids
grown from acidic solutions.12 For those series the concor-
dance between the composition of the extracting oxonium
species and the CE size as reported by P. Junk in his review13
was also registered.
Complexes of macrocyclic ligands (CEs, cyclodextrins) with
HAuCl4 and HAuBr4 as potential extractable forms in the pro-
cesses of gold extraction from acidic aqueous solutions con-
tinue to attract attention both from the viewpoint of their
structures and various processes accompanying their for-
mation.14 J. Steed et al. reported nine oxonium tetrachloro-
aurate(III) CE salts.14b,c The intriguing feature disclosed in that
study was that the high affinity of benzo-crown ethers (BCE)
toward nitration in the aggressive medium of aqua regia
resulted in nitrated macrocycles, 4′-nitro-B15C5 for the starting
B15C5, 4′-nitro-B18C6 for B18C6, and dinitrodi-B30C10 for
di-B30C10. Although the replacement of concentrated acidic
solution by the diluted aqueous solutions of HAuCl4 resulted
in unnitrated products in the cases of B15C5 and di-B24C8,
no success has been achieved with B18C6.
aA.V. Bogatsky Physico-Chemical Institute of National Academy of Sciences of
Ukraine, Lustdorfskaya doroga 86, 65080 Odessa, Ukraine
bInstitute of Applied Physics Academy of Sciences of Moldova, Academy str. 5,
MD2028 Chisinau, Moldova. E-mail: fonari.xray@phys.asm.md;
Fax: +(373 22) 725887; Tel: +(373 22) 738154
†CCDC 915387–915388, 979074–979075. For crystallographic data in CIF or
other electronic format see DOI: 10.1039/c4dt00017j
This journal is © The Royal Society of Chemistry 2014
Dalton Trans.

View Article Online
Paper
Dalton Transactions
1
These gaps have encouraged us to undertake this research sis, H, 13C NMR, and EI-FAB-MS spectrometry identified the
to shed light upon the possibility to obtain solid complex with resulting bright yellow crystalline solid as a complex with the
non-substituted B18C6 using the reaction medium free from composition [(H3O)(B18C6)][AuCl4] 2. The lower yield (51%) in
nitrates. As far as the reported data have indicated the ease of comparison with of those of the other complexes we explain by
nitration of the BCE aromatic ring by nitric acid as a com- its solubility in large amounts of water added to the reaction
ponent of used aqua regia,13 in our study we prepared the solu- medium. The poor crystal quality did not allow obtaining
tion of HAuCl4 free from nitrates14b in order to avoid the reliable X-ray data for structure solution. The elaboration of
unwanted nitration.
recrystallization conditions is in progress. In the case of 4′-Br-
This contribution summarises the preparation and crystal B18C6 the good quality large crystals of the complex with the
structures for new BCE oxonium tetrahalogenaurate(III) composition [(H3O)(4′-Br-B18C6)][AuCl4] 3 were grown from a
(Hal = Cl, Br) complexes. The reported compounds are [(H3O)- chloroform solution in a day.
(B18C6)0.58(4′-Cl-B18C6)0.42][AuCl4] 1, [(H3O)(B18C6)][AuCl4] 2,
In order to obtain additional data on other possible modifi-
[(H3O)(4′-Br-B18C6)][AuCl4] 3, [(H3O)(4′-Br-B18C6)][AuBr4] 4, cations of the ligands in identical synthetic conditions we
and [(H3O)(B18C6)][AuBr4] 5. The composition and structures extended the number of the studied objects and prepared the
for 1, 3, 4 and 5 were proved by single crystal X-ray crystallogra- complexes from the same starting materials as for 1 and 2, but
phy. The impact of halogen–halogen interactions in the crystal in HBr medium. For the all starting bromo-containing
packing is demonstrated.
reagents, namely, 4′-Br-B18C6 and a solution of HAuBr4 in
HBr, salt with the expected composition, [(H3O)(4′-Br-B18C6)]-
[AuBr4] 4, was obtained. Mixing of B18C6 with HAuCl4 in HBr
solution resulted in gray-brown precipitate, which has
become red-brown in 30 min. The filtered, water-washed and
dried precipitate was crystallized from chloroform. Large,
Results and discussion
Synthetic procedures
B18C6 and 4′-Br-B18C6 were chosen as starting macrocycles. lustrous dark-ruby crystals were grown in a few hours. The
The sample of BCE was dissolved at 15 °C in half-diluted HCl crystalline complex was identified as [(H3O)(B18C6)][AuBr4] 5.
or HBr acids (acid–water = 1 : 1). The corresponding BCE and Thus, two facts have been established: (a) unlike complex 1,
HAuHal4 were taken in the molar ratio 1 : 1. The bright-yellow under the same conditions halogenation of the ligand
for the tetrachloroaurate(III), and the grey- and red-brown for does not occur in 5; (b) in the presence of HBr the [AuCl4]−
tetrabromoaurate(III) precipitates were formed instantly, and anion is completely transformed into the [AuBr4]− anion. The
the solutions were getting almost colorless. The precipitates were control experiment revealed that when B18C6 was mixed with
separated by filtration and washed with several small portions of HAuCl4 in HCl solution in the presence of 2–3 drops of HBr,
the ice-cold distilled water, then the precipitates were air dried the mixture also produced a red-brown complex practically
for 12 h and placed into corresponding solvents for growth the identical to 5 (X-ray), but with a slightly lower melting point.
crystals suitable for X-ray analysis. In the case of B18C6 it took Crystals 4 and 5 were easily grown from the chloroform
several months for elaboration conditions for crystal growth, solution and represent suitable objects for comparison with
and the product was finally identified as the mixed-ligand 1 and 3.
complex, [(H3O)(B18C6)0.58(4′-Cl-B18C6)0.42][AuCl4] 1. The crys-
Taking into account the ease of practically quantitative con-
tals of 1 were grown from an ethanol–ethyl acetate mixture. To version of HAuCl4 crown ether complexes into the corres-
monitor the final compositions of complexes the preliminary ponding HAuBr4 complexes, the composition of 2 was proved
experiments were carried out where two equal portions of by its treatment with an aqueous solution of 40% HBr. The
HAuCl4 were added to the solution of BCE in two successive resulting ruby color powder dissolved in chloroform yielded
steps, the second portion being added to the filtrate after the the perfect crystals identical with complex 5. Thus, the lack of
removal of the first portion of precipitate and the solution chlorination has been confirmed for the product obtained
bleaching. Both portions of precipitates were dried and after from dilute solution of HAuCl4. A similar procedure under-
weighing had equal weights. In the second preliminary experi- taken for the crystals precipitated from concentrated HCl and
ment the half amount of BCE solution was added to the calcu- stored in solution only for 24 hours resulted in a solid also
lated amount of HAuCl4 and then, after the separation of completely identical with complex 5. Thus, in a concentrated
sediment, the second portion of the BCE solution was added. solution of reactants the chlorination of B18C6 does not
In this case the masses of two precipitated samples also occur as well. Consequently, one can reasonably assume that
coincided. Thus, a preliminary conclusion about the 1 : 1 stoi- complex 1 is formed from complex 2 due to its long-term
chiometries of the obtained complexes was made. This con- contact with oxygen, which promotes oxidative chlorination of
clusion was further confirmed by the single crystal X-ray the electrophilic benzene ring. Taking into account the possi-
diffraction experiments. In order to avoid the unwanted chlori- bility of aerobic oxidation of hydrogen chloride to molecular
nation of B18C6, that accompanied the growth of complex 1, chlorine with subsequent activation of the latter by gold(III) tri-
the next crystallization experiment was carried out with the chloride, the following sequence of transformations can be
same reactants as in 1, but from solution several times diluted proposed resulting in the chlorinated B18C6 [see transform-
with water. The attempt was successful, and elemental analy- ations (1)–(3) and scheme]:
Dalton Trans.
This journal is © The Royal Society of Chemistry 2014

View Article Online
Dalton Transactions
Paper
a = 10.829, b = 12.19, c = 8.799 Å, β = 113.86°, V = 1062 Å3 indi-
cated presumably in favor of the solvate with the composition
(H3O)[AuCl4]·nH2O·nCH3OH, and the small-crystallinity con-
glomerates for which diffraction patterns have not been
resolved. Analysis of crystallographic data (Table 1) revealed
that compounds 3 and 4 are isomorphous and isostructural
with the unit cell dimensions increase in 4 against 3 pro-
portional to the increase in the atomic radii from Cl to Br.
This gave us a reason to discuss them together.
4HCl þ O2 ! 2H2O þ 2Cl2
HAuCl4 ⇄ HCl þ AuCl3
AuCl3 þ Cl2 ⇄ ½AuCl4ꢀꢁ þ Clþ
ð1Þ
ð2Þ
ð3Þ
The view of complexes 1, 3, 4 and 5 is shown in Fig. 1. All of
them have similar units, BCE-macrocycle centered by the
oxonium cation, and the tetrahalogenaurate [AuHal4]− (Hal =
Cl, Br) anion in the ratio 1 : 1 : 1. The crown molecules have
similar concave shapes typical for the previously reported
oxonium-B18C6 units to provide the best accommodation of
the H3O+ cation.12–14 The oxonium cations are held in the
macrocyclic cavities by sets of insignificantly different OH⋯O
interactions, being bifurcated ones in 1, 3, and 4, and single
ones in 5, the O⋯O distances falling in the range 2.52(2)–
2.845(9) Å (Table 2).
The crystal packing for complexes 1, 3, 4 and 5, distinctive
by the presence/absence of the halogen substituent in the CE’s
aromatic ring, and the halogen Cl vs. Br in the tetrahalogen-
aurate anion indicates that these solids are rather similarly
laminated structures with alternating organic cationic and
inorganic anionic layers (Fig. 2a–d).
The exclusive chlorination of B18C6 in the form of complex 1
is explained by the more strong electrophilic function of Cl+
against Br+.
X-ray study
Single crystal X-ray data were obtained for four solids, [(H3O)-
(B18C6)0.58(4′-Cl-B18C6)0.42][AuCl4] 1, [(H3O)(4′-Br-B18C6)]-
[AuCl4] 3, [(H3O)(4′-Br-B18C6)][AuBr4] 4, and [(H3O)(B18C6)]-
[AuBr4] 5. In experiments starting from 4′-Br-B18C6, the final
complexes 3 and 4 comprise the same brominated macrocycle.
In the case of starting with B18C6 the reaction carried out in
HCl medium resulted in the mixed-ligand complex 1 that com-
prises both the non-substituted and chlorinated macrocycles
approximately in the 1 : 1 ratio, while in HBr medium the reac-
tion resulted in complex 5 that comprises initial B18C6.
Complex [(H3O)(B18C6)][AuCl4] 2 crystallizes either as amor-
phous non-diffracting solid from CHCl3, or as a mixture of two
types of crystals from CH3OH, very thin yellow needles weakly
diffracted and allowing to define only the unit cell dimensions,
The cationic layers are composed of centrosymmetric
macrocyclic dimers with partial overlapping of aromatic rings
providing the offset face-to-face π–π stacking interactions with
centroid–centroid separation of 3.989
Å and interplanar
spacing of 3.621 Å in 1, 3.926 and 3.723 Å in 3, 4.148 and
3.712 Å in 4, and 3.657 and 3.560 Å in 5 (Fig. 3). The additional
stabilization of the dimeric capsules is provided by the Hal⋯O
Table 1 Crystal data and structure refinement for 1, 3, 4 and 5
Identification code
1
3
4
5
Empirical formula
Formula weight
C16H26.58AuCl4.42O7
684.47
C16H26AuBrCl4O7
749.04
C16H26AuBr5O7
926.88
C16H27AuBr4O7
847.98
Crystal system
Space group
Orthorhombic
Pbca
Monoclinic
P21/c
Monoclinic
P21/c
Triclinic
P1
ˉ
Unit cell dimensions
a/Å
b/Å
c/Å
α/°
β/°
9.4261(8)
20.8400(9)
24.3248(13)
90
90
90
4778.4(5)
8
1.903
10.2656(3)
25.3739(9)
9.5914(3)
90
99.108(2)
90
2466.85(14)
4
2.017
10.3648(4)
25.8306(8)
9.8815(3)
90
100.034(4)
90
2605.10(16)
4
2.363
8.6437(3)
12.6822(8)
13.1609(7)
61.475(6)
77.130(4)
87.395(4)
1232.61(11)
2
γ/°
Volume/Å3
Z
Dcalcd/Mg m−3
2.285
12.482
μ/mm−1
6.684
8.049
13.347
F(000)
2661.2
11 074
1440
11 190
1728
8868
796
7259
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2σ(I)] R1, wR2
R indices (all data) R1, wR2
Largest diff. peak and hole/e Å−3
4666 [Rint = 0.0577]
4666/9/260
1.072
0.0577, 0.1078
0.1121, 0.1336
0.821 and −1.079
4833 [Rint = 0.0350]
4833/3/281
1.016
0.0413, 0.0707
0.0689, 0.0805
0.936 and −0.680
4907 [Rint = 0.0314]
4907/6/281
1.002
0.0533, 0.1028
0.0943, 0.1150
1.080 and −1.550
4540 [Rint = 0.0399]
4540/0/266
1.007
0.0362, 0.0742
0.0553, 0.0814
1.025 and −0.917
This journal is © The Royal Society of Chemistry 2014
Dalton Trans.

View Article Online
Paper
Dalton Transactions
Fig. 1 ORTEP drawings for 1, 3, 4 and 5. (a) View of complex 1. Thermal ellipsoids are shown with 30% probability level. Non-chlorinated B18C6
and chlorinated 4’-Cl-B18C6 occupy the same place in the unit cell with the occupancies 0.58 and 0.42. (b) View of complex 3. (c) View of complex
4. (d) View of complex 5. Thermal ellipsoids are shown with 50% probability level.
(crown) interactions registered in 1, 3, and 4 that include: dibenzo-CE complexes reveals that offset face-to-face π⋯π
Br(1B)⋯O(4) = 3.202 Å, ∠OBrC = 171°, Br(1B)⋯O(7) = 3.416 Å, stacking interactions between the benzene rings occurs only in
∠OBrC = 121° in 1; Cl(5B)⋯O(4) = 2.955 Å, ∠OClC = 161°; thirteen structures (33%). At the same time in the subset of
Cl(5B)⋯O(7) = 3.099 Å, ∠OClC = 110° in 3, and Br(1)⋯O(4) = seventeen 18-membered CE complexes eight (47%) reveal such
3.304 Å, ∠OBrC = 169° in 4.
interactions, and our study increases this percentage up to
A survey of the CSD (version 5.35, last update November 57% (12 from 21), while the subset of the remaining twenty
2013) revealed forty oxonium complexes of 12-, 15-, 18-, 24-, three complexes involving the CEs of the other sizes reveals
and 30-membered benzo- and dibenzo-CEs. This set includes only five structures (22%) with π⋯π stacking interactions. Con-
tetrabromo-, tetrachloro-dibenzo-, dibromo-, dinitro-benzo-, sequently, the oxonium complexes with substituted and non-
mono-substituted nitro-benzo- and unsubstituted BCEs. No substituted 18-membered benzo- and dibenzo-CEs might be
oxonium complexes with the monobromo- or monochloro- considered as the most predisposed for π⋯π stacking inter-
BCEs have been reported so far, and our study fills this gap. actions. The co-existence of two different crown ether mole-
Analysis of the crystal packing for all these forty benzo- and cules in 1, which occupy approximately the same place in the
Dalton Trans.
This journal is © The Royal Society of Chemistry 2014

View Article Online
Dalton Transactions
Paper
BCEs containing an aromatic system enriched in electrons;
hydrogen halogen acid as the source of oxonium ions, and the
halogen atom in the form of tetrahalogenaurate(III) anions.
The oxidizing agent, capable of oxidizing halide ions to free
halogen Lewis acid, catalyzes the electrophilic aromatic substi-
tution. Our study disclosed that in the absence of nitrate ions,
or other strong oxidizing agents, of the pair tetrachloroaurate(III)
anion vs. tetrabromoaurate(III) anion only the former acts
as a Lewis acid-oxidizing agent in the acidic solutions under
aerobic conditions.
The literature on dibenzo-CEs which can also get halo-
genated and form similar structures as the mono-benzo substi-
tuted counterparts gives an interesting reported example.15
However, in that contribution the reaction medium contained
either free bromine and iron, or an excess of free bromine
making the formation of tetrabromodibenzo-18C6 easily
understandable.
Table 2 Hydrogen bonds for 1, 3, 4 and 5 [Å and °]
D–H⋯A
d(H⋯A)
d(D⋯A)
<(DHA)
1
O(1W)–H(3W)⋯O(3)
O(1W)–H(3W)⋯O(4)
O(1W)–H(1W)⋯O(2)
O(1W)–H(1W)⋯O(1)
O(1W)–H(2W)⋯Cl(5)#1
3
1.95(12)
2.08(14)
1.92(11)
2.17(13)
2.46(11)
2.712(18)
2.768(15)
2.664(13)
2.771(15)
3.224(15)
142(18)
132(16)
140(14)
123(13)
143(16)
O(7)–H(72)⋯O(5)
O(7)–H(71)⋯O(3)
O(7)–H(73)⋯O(2)
O(7)–H(73)⋯O(1)
4
O(7)–H(73)⋯O(2)
O(7)–H(73)⋯O(1)
O(7)–H(71)⋯O(3)
O(7)–H(72)⋯O(5)
O(7)–H(72)⋯O(4)
5
1.76(2)
1.88(3)
2.17(4)
1.99(2)
2.587(5)
2.691(7)
2.687(5)
2.840(6)
156(5)
152(5)
116(4)
159(4)
2.02(6)
2.04(4)
1.81(3)
1.98(7)
2.36(7)
2.647(9)
2.845(9)
2.695(10)
2.603(9)
2.799(10)
125(6)
148(7)
167(8)
125(8)
110(6)
O(7)–H(73)⋯O(6)
O(7)–H(72)⋯O(4)
O(7)–H(71)⋯O(2)
1.88(3)
1.89(3)
1.67(3)
2.72(2)
2.75(2)
2.52(2)
166(7)
175(7)
174(5)
Conclusions
Symmetry transformations used to generate equivalent atoms: #1 −x,
1 − y, 1 − z.
Synthetic procedures have been elaborated that allowed exclud-
ing aqua regia from the process of tetrahalogenaurate(III)
extraction from the acidic solutions in the presence of macro-
cyclic ligands. The use of free from nitric acid aqueous solu-
tion of HAuCl4/HauBr4 allowed avoiding unwanted nitration of
the initial B18C6 and bromo-substituted 4′-Br-B18C6, and
resulted in new complexes, [(H3O)(B18C6)0.58(4′-Cl-B18C6)0.42]-
[AuCl4] 1, [(H3O)(B18C6)][AuCl4] 2, [(H3O)(4′-Br-B18C6)][AuCl4]
3, [(H3O)(4′-Br-B18C6)][AuBr4] 4, and [(H3O)(B18C6)][AuBr4] 5.
Compositions and structures for 1, 3, 4, and 5 were unequivo-
cally determined by single crystal X-ray diffraction. For the first
time the mixed-ligand complex 1 has been reported where
non-substituted and chlorinated macrocycles co-crystallize in
about a 1 : 1 ratio in the crystal lattice. For the first time the
complete conversion of [AuCl4]− to [AuBr4]− anion has been
demonstrated for this system that resulted in isomorphous
and isostructural complexes 3 and 4. The composition of 2 was
proved by elemental analysis, 1H, 13C NMR, and mass-spec-
trometry has also been confirmed by its transformation to the
brominated analogue 5. From a crystal engineering viewpoint
the reported compounds enrich the available data for the bis-
(oxonium-BCE) centrosymmetric dimeric capsule as a robust
supramolecular synthon sustained by the interplay of π–π
stacking interactions and halogen-based contacts. The dense
inorganic anionic networks sustained by short Cl⋯Cl and
Br⋯Br contacts were registered in all crystals as additional
structure-directed factor for laminated solids. The ease of pre-
cipitation of stoichiometric products 4 and 5 accompanied by
practically quantitative yields makes them very promising can-
didates for gold extraction from acidic solutions.
crystal structure, and the similar packing motifs in 1 and 3
also indicate in favor of the reliability and importance of stack-
ing interactions in such complexes (Fig. 3).
The similar anionic layers in 1, 3 and 4 are built of the
almost perfectly aligned [AuCl4]− anions in 1, 3 and [AuBr4]−
anions in 4 (Fig. 4). In 1 the anions, situated parallel to the ac
plane, form slightly corrugated sheets (the symmetry related
anions deviate from planarity at 4.41, 4.88, 14.88 and 15.52°)
sustained by the short Cl⋯Cl contacts of 3.191 and 3.429 Å
that involve all Cl atoms, the Au⋯Au separations within the
sheet being 7.608 and 7.800 Å. In 3 the anions perfectly align
in the bc plane (deviation is only 3.39° in 3 and 2.07° in 4)
with the only one short contact Cl(3)⋯Cl(3)(−x, 1 − y, −z) =
3.279 Å that combines the adjacent anions in dimers, three
other Cl⋯Cl distances being in the range 3.647–3.673 Å, the
Au⋯Au separations within the sheet being 7.468, 8.101 and
8.169 Å. Of the known examples only in (H5O2)(DB24C8)-
[AuCl4]14b the [AuCl4]− anions are aligned in the layer with two
Cl⋯Cl contacts of 3.230 and two of 4.127 Å. The architecture
of the anionic network in 4 completely reproduces that in 1
with the rather short Br⋯Br contacts being in the range
3.296–3.535 Å, the Au⋯Au separations being 7.794, 8.236 and
8.272 Å. The anionic network in 5 situated parallel to the ab
plane reveals an essential difference from all the above dis-
cussed samples as far as it is built of the two crystallographi-
cally different [AuBr4]− anions inclined to each other at an
angle of 51.5°. Nevertheless, 6 of 8 bromine atoms are involved
in the short Br⋯Br contacts of 3.488 and 3.594 Å, the Au⋯Au
separations being compatible with structure 1 and equal to
7.510 and 7.834 Å.
Experimental
General
All solvents were purified by standard procedure before use.16
The trade acids were used without additional purification.
The halogenation of BCE in hydrogen halogen acid media
has been previously reported.10,11,14b Similar processes should
occur in systems composed of identical components, namely,
This journal is © The Royal Society of Chemistry 2014
Dalton Trans.

View Article Online
Paper
Dalton Transactions
Fig. 2 Crystal packing in 1 (a), 3 (b), 4 (c), and 5 (d). H-atoms are omitted for clarity.
B18C6 was prepared similar to the known technique.17 4′-Br- benzyl alcohol matrix was utilized. EI-Mass spectra were
B18C6 was prepared under elaborated by us technique.18
obtained with a MX 1321 spectrometer equipped with a
A
nitrate-free aqueous solution of HAuCl4 was prepared accord- direct inlet; ionization voltage 70 eV and ionization chamber
ing to the known method.19 The free from nitrates solution temperature 200 °C. Elemental analysis was carried out on
HAuBr4, has been obtained similarly using 40% HBr instead a EuroVector EA3000 CHNS elemental analyzer. The sum
of HCl.
of halogens was determined by the Schöniger flask test by
the sample burning in the oxygen atmosphere using
platinum catalyst, followed by mercurimetric titration of
the halogenated combustion products in the presence of
diphenylcarbazone.20
Instrumentation
1H NMR spectra were obtained on
a Varian VXR-300
(299.94 MHz) spectrometer and a Bruker Advance DRX 500
(500.07 MHz) spectrometer; 13C NMR were obtained on a
Bruker Advance DRX 500 (125.74 MHz) spectrometer. All
General procedure for the synthesis of complexes 1–5
chemical shifts are quoted in ppm on the δ scale with TMS or A gold slug (0.10 g, 0.51 mmol) was treated with the mixture of
residual solvent as an internal standard. The coupling con- HNO3 (0.5 mL 63%), conc. HCl (2 mL) (HBr for 5) and distilled
stants are expressed in Hz. The melting points were deter- H2O (5 mL), and the mixture was stirred for 30 min at room
mined by the open capillary tube method and were temperature. Then the orange solution was heated on a
uncorrected. Fast atom bombardment (FAB) mass spec- boiling-water bath at reduced pressure to complete the liquid
trometry was performed on a VG 70-70EQ mass spectrometer, distillation. The conc. HCl (HBr for 5) (5 mL) was added in a
equipped with an argon primary atom beam, and an m-nitro- trice to the remaining melt each time removing the liquid. The
Dalton Trans.
This journal is © The Royal Society of Chemistry 2014

View Article Online
Dalton Transactions
Paper
Fig. 3 Cationic layers and centrosymmetric dimers in 1 (a, d), 3 (b, e), and 5 (c, f). H-atoms are omitted for clarity. Short interatomic contacts are
shown by thin cross-hatching lines, centroid–centroid distances are shown by thick cross-hatching lines. As far as the halogen-based interactions
are essential in the crystal lattice stabilization, the chlorinated BCEs are shown in the crystal packing of 1.
residue was dissolved in a mixture of conc. HCl (HBr for 5) AuCl4O7) + 0.41·(C16H26AuCl5O7)] C, 28.10; H, 3.92; Cl, 22.80.
(2 mL) and H2O (5 mL) and the resulting solution was used Found: C, 28.03; H, 3.97; Cl, 22.92.
later on. The corresponding BCE (0.198 g for 1, 5, and 0.158 g
[(H3O)(B18C6)][AuCl4] (2). The crude product was recrystal-
for 2, 3, 4), (0.51 mmol) was dissolved in mixture of distilled lized from CHCl3 to give an orange solid. Yield: 0.168 g, 51%;
water (5 mL) and conc. HCl (for 1, 2, 3) or HBr (for 4, 5) Mp: 133–135 °C (dec.) (complex decomposition without
(2 mL). The resulting solution was mixed with HAuCl4 solution melting begins at 105 °C). 1H NMR (CDCl3): δ 3.82 (s, 4H,
(HAuBr4 for 5) and the precipitation of the bright-yellow (1, 2, OCH2CH2O); 3.85 (m, 4H, CH2O); 3.92 (m, 4H, OCH2), 4.08 (m,
3), grey-brown (4) and red-brown (5) crystals was observed 4H, CH2O), 4.31 (m, 4H, OCH2), 6.97 (s, br, 2H, Ar); 7.01, (s,
immediately. To obtain complex 3 the starting solution br, 2H, Ar); 10.89–11.01, (s, br, 3H, H3O+).13C NMR (CDCl3):
HAuCl4 has been additionally diluted by 25 mL of distilled δ 67.22; 69.47; 70.08; 70.19; 70.29; 112.08; 122.45; 146.00;
water. After 30 min the precipitate was filtered off, washed FAB-MS, m/z (%): 331 ([B18C6 + H3O]+, 42); 312 ([B18C6]+, 21).
with cold distilled water (3 × 1 mL) and recrystallized to obtain EI-MS, m/z (%): 312([B18C6]+, 25); 136 ([B18C6-(CH2CH2O)4]+,
crystals suitable for X-ray investigation.
[(H3O)(B18C6)0.58(4′-Cl-B18C6)0.42][AuCl4] (1). The crude 28.68; H, 4.06; Cl, 21.16. Found: C, 28.57; H, 4.11; Cl, 21.30.
complex 1 was placed in the 10 mL test tube at 15 °C and dis- [(H3O)(4′-Br-B18C6)][AuCl4] (3). The crude product was
92); 44 ([C2H4O]+, 100) Anal. Calcd for C16H27AuCl4O7: C,
solved in a minimum amount of ethanol. Ethyl acetate was recrystallized from CHCl3 to give orange crystals of 1. Yield:
added dropwise until appearance of a slight turbidity of the 0.284 g, 75%; Mp: 140 °C (dec.) (complex decomposition
solution, and then the test tube was closed by stopper fitted without melting begins at 109 °C). 1H NMR (CDCl3): δ
with a wide capillary, allowing the slowly evaporation of 3.80–3.87, (m, 4H, CH2O); 3.83 (s, 4H, CH2O); 3.89–3.95 (m,
solvent. After about a week the small orange crystals appeared 4H, CH2O), 4.05–4.11 (m, 4H, CH2O), 4.23–4.30 (m, 4H,
3
2
on the walls of the test tube. In the absence of a crystal with CH2O), 7.04 (d, 1H, J = 1.87, Ar); 7.11–7.14, (dd, 1H J = 8.72,
the quality required for X-ray diffraction analysis the procedure 3J = 1.87, Ar); 7.19, (s, br, H3O+). 13C NMR (CDCl3): δ 67.56;
was repeated by successive addition of ethanol and ethyl 67.61; 69.39; 69.44; 70.10; 70.16*; 70.26; 70.44; 70.52; 113.29;
acetate portions. Yield: 0.264 g. Complex decomposition 114.26; 115.52; 125.02; 145.51; 146.80 (* double intensity);
without melting begins at 105 °C. FAB-MS, m/z (%): 331 FAB-MS, m/z (%): 410 ([Br-B18C6 + H3O]+, 32); 392 ([Br-B18C6
([B18C6 + H3O]+, 77); 313 ([B18C6 + H]+, 28). EI-MS, m/z (%):
+
H], 18). EI-MS, m/z (%): 391 ([Br-B18C6]+, 15); 215
346, ([Cl-B18C6]+, 15) 312, ([B18C6]+, 77, 214 ([Cl-B18C6- ([Br-B18C6-(CH2CH2O)4]+, 78); 44 ([C2H4O]+, 100) Anal. Calcd
(CH2CH2O)3]+, 25); 170, ([Cl-B18C6-(CH2CH2O)4]+, 100); 136, for C16H26AuBrCl4O7: C, 25.66; H, 3.50; (Br + Cl), 29.58. Found:
([B18C6-(CH2CH2O)4]+, 55). Anal. Calcd for: [0.59·(C16H27- C, 25.71; H, 3.52; (Br + Cl), 29.66.
This journal is © The Royal Society of Chemistry 2014
Dalton Trans.

View Article Online
Paper
Dalton Transactions
Fig. 4 Fragments of anionic networks in 1 (a) The Cl⋯Cl contacts are: Cl(1)⋯Cl(3) (x − 0.5, y, 0.5 − z) = 3.429, C2(1)⋯Cl(4) (x − 0.5, 0.5 − y, 1 − z) =
3.192 Å, angles AuClCl being in the range 153–165°, separations Au⋯Au being 7.608 and 7.800 Å; 3 (b), 4 (c), and 5 (d).
[(H3O)(4′-Br-B18C6)][AuBr4] (4). The crude product was X-ray crystallography
recrystallized from CHCl3 to give red-brown crystals of 5. Yield:
0.460 g, 98%; Mp: 165 °C 1H NMR (CDCl3): δ 3.87, (m, 8H, X-ray data were collected at room temperature on an Oxford
CH2O; OCH2CH2O); 3.98 (m, 4H, CH2O); 4.13 (m, 4H, CH2O), Diffraction Xcalibur diffractometer equipped with CCD area
4.29 (m, 4H, CH2O), 5.80, (s, br, 3H, H3O+); 6.83–6.85 (d, 1H, detector and a graphite monochromator utilizing MoKα radi-
2
2J = 8.82, Ar); 7.05, (c, 1H, Ar); 7.14–7.15, (d, 1H J = 8.82, Ar); ation. Final unit cell dimensions were obtained and refined on
13C NMR (CDCl3): δ 67.69; 67.75; 69.37; 69.43; 70.14; 70.19*; an entire data set. Lorentz and polarization corrections as well
70.28; 70.47; 70.54; 113.50; 114.13; 115.66; 124.93; 145.75; as empirical absorption were applied for collected data set. All
147.06 (* double intensity); FAB-MS, m/z (%): 410 ([Br-B18C6 + calculations to solve the structures and to refine the models
H3O]+, 46); 392 ([Br-B18C6 + H]+, 11). EI-MS, m/z (%): 390; 392 proposed were carried out with the programs SHELXS97 and
([Br-B18C6]+, 22); 215; 217([Br-B18C6-(CH2CH2O)4]+, 88); SHELXL97.21 All non-hydrogen atoms were modeled in aniso-
44 ([C2H4O]+, 100) Anal. Calcd for C16H26AuBr5O7: C, 20.73; tropic approximation. In 1 the macrocyclic molecules B18C6
H, 2.83; Br, 43.10. Found: C, 20.79; H, 2.87; Br, 29.75.
and 4′-Cl-B18C6, and the associated with them oxonium
[(H3O)(B18C6)][AuBr4] (5). The crude product was recrystal- cations were modeled and refined independently and resulted
lized from CHCl3 to give red-brown crystals of 4. Yield: 0.321 g, in the occupancies distribution of 0.58(1) and 0.42(1) between
99%; Mp: 146 °C 1H NMR (CDCl3): δ 3.85, (s, 4H, OCH2CH2O); these molecular complexes that occupy approximately the
3.88 (m, 4H, CH2O); 3.96 (m, 4H, OCH2), 4.12 (m, 4H, CH2O), same place in the crystal. The [AuCl4]− was ordered. Disorder
4.33 (m, 4H, OCH2), 6.97–6.98 (d, 2H, 2J = 3.37, Ar); 7.01, in 3 was modeled in terms of two alternative positions of
(d, 2H 2J = 3.37, Ar); 10.76–11.0, (s, br, 3H, H3O+). 13C NMR bromine atom with occupancies 0.930(2) and 0.070(2) at C(14)
(CDCl3): δ 67.26; 69.57; 70.15; 70.27; 70.40; 112.12; 122.53; and C(15) atoms, respectively. Disorder in 4 was modeled in
145.98; FAB-MS, m/z (%): 331 ([B18C6 + H3O]+, 43); 312 terms of two alternative positions of bromine atom with occu-
([B18C6]+, 11). EI-MS, m/z (%): 312 ([B18C6]+, 19); 136 ([B18C6- pancies 0.875(3) and 0.125(3) at the same atoms. The oxonium
(CH2CH2O)4]+, 85); 44 ([C2H4O]+, 100) Anal. Calcd for oxygen in 5 occupies two positions with the occupancies of
C16H27AuBr4O7: C, 22.66; H, 3.21; Br, 37.69. Found: C, 22.58; 0.51(7) and 0.49(7), and was refined with the common
H, 3.34; Br, 37.76.
H-atoms. Hydrogen atoms were placed in calculated positions
Dalton Trans.
This journal is © The Royal Society of Chemistry 2014

View Article Online
Dalton Transactions
Paper
and allowed to ride on the C-atoms to which they were
attached with an isotropic thermal parameter 1.2 times that of
the parent atom. Atomic coordinates, bond lengths and
angles, and thermal parameters were deposited as cif files at
the Cambridge Crystallographic Data Centre. CCDC
915387–915388, and CCDC 979074–979075.
J. Lipkowski, Zh. Neorg. Khim., 2001, 46(11), 1833–1840;
(b) M. S. Fonari, N. G. Furmanova, W.-J. Wang, E. V. Ganin,
I. A. Verin, Yu. A. Simonov and V. O. Gelmboldt, Crystallogr.
Rep., 2006, 51(5), 804–810; (c) M. S. Fonari, O. A. Alekseeva,
N. G. Furmanova, K. A. Lyssenko, W.-J. Wang, S.-W. Tang,
E. V. Ganin, V. O. Gelmboldt and Yu. A. Simonov, Crystal-
logr. Rep., 2007, 52(2), 253–259; (d) M. S. Fonari, Yu.
A. Simonov, W.-J. Wang, S.-W. Tang, E. V. Ganin,
V. O. Gelmboldt, T. S. Chernaya, O. A. Alekseeva and
N. G. Furmanova, Polyhedron, 2007, 26(18), 5193–5202;
(e) N. G. Furmanova, M. K. Rabadanov, T. S. Chernaya,
M. S. Fonari, Yu.A. Simonov, E. V. Ganin, V. O. Gelmboldt,
R. Ya. Grigorash, S. A. Kotlyar and G. L. Kamalov, Crystal-
logr. Rep., 2008, 53(2), 246–252; (f) M. S. Fonari,
V. Ch. Kravtsov, Yu. A. Simonov, S. S. Basok, E. V. Ganin,
V. O. Gelmboldt, K. Suwinska, J. Lipkowski, O. A. Alekseeva
and N. G. Furmanova, Polyhedron, 2008, 27, 2049–2058;
(g) M. S. Fonari, N. G. Furmanova and Yu. A. Simonov,
J. Struct. Chem., 2009, 50(Suppl 1), 124–135.
References
1 C. J. Pedersen, J. Am. Chem. Soc., 1967, 89(26), 7017–7036.
2 C. J. Pedersen, J. Am. Chem. Soc., 1967, 89(10), 2495–2496.
3 G. W. Gokel, Crown ethers and cryptands, Royal Society of
Chemistry, 1994, ISBN-13: 978-0851867045.
4 J. W. Steed, Coord. Chem. Rev., 2001, 215, 171–221.
5 (a) B. Martinez-Haya, P. Hurtado, A. R. Hortal, S. Hamad,
J. D. Steill and J. Oomens, J. Phys. Chem. A, 2010, 114,
7048–7054; (b) P. Hurtado, A. R. Hortal, F. Gamez,
S. Hamad and B. Martinez-Haya, Phys. Chem. Chem. Phys.,
2010, 12, 13752–13758.
6 A. Späth and B. König, Beilstein J. Org. Chem., 2010, 6, 32.
13 P. C. Junk, New J. Chem., 2008, 32, 762–773.
7 (a) F. Gamez, P. Hurtado, B. Martinez–Haya, G. Berden and 14 (a) Z. Liu, M. Frasconi, J. Lei, Z. J. Brown, Z. Zhu, D. Cao,
J. Oomens, Int. J. Mass Spectrom., 2011, 308, 217–224;
(b) R. D. Rogers, L. K. Kurihara and M. M. Benning,
J. Inclusion Phenom., 1987, 5, 645–658; (c) R. D. Rogers,
L. K. Kurihara and M. M. Benning, Inorg. Chem., 1987, 26,
4346–4352; (d) R. D. Rogers, A. H. Bond, W. G. Hipple,
A. N. Rollins and R. F. Henry, Inorg. Chem., 1991, 30, 2671–
J. Iehl, G. Liu, A. C. Fahrenbach, Y. Y. Botros, O. K. Farha,
J. T. Hupp, C. A. Mirkin and J. F. Stoddart, Nat. Commun.,
2013, 4, 1855, DOI: 10.1038/ncomms2891; (b) M. Calleja,
K. Johnson, W. J. Belcher and J. W. Steed, Inorg. Chem.,
2001, 40, 4978–4985; (c) K. Johnson and J. W. Steed, Chem.
Commun., 1998, 1479–1480.
2679; (e) R. D. Rogers, A. H. Bond and S. Aguinaga, J. Am. 15 K. M. Fromm, R. D. Bergougnant and A. Y. Robin, Z. Anorg.
Chem. Soc., 1992, 114, 2960–2967; (f) R. D. Rogers and
L. K. Kurihara, Inorg. Chem., 1987, 26, 1498–1502.
8 Y. Y. Ding, Y. W. Qiuyin and Y. Z. P. Guangming, J. Nucl.
Radiochem., 1982, 4(1), 21–27.
Allg. Chem., 2006, 632, 828–836.
16 W. L. F. Armarego and C. L. L. Chai, Purification
of Laboratory Chemicals, Elsevier, Burlington, 6th edn,
2009.
9 J. L. Atwood, S. G. Bott, A. W. Coleman, K. D. Robinson, 17 N. Lukyanenko, Janssen Chim. Acta, 1992, 10(1), 12–18.
S. B. Whetstone and C. M. Means, J. Am. Chem. Soc., 1987, 18 S. A. Kotlyar and S. M. Pluzhnik-Gladyr, Macroheterocycles,
109, 8100–8101.
2008, 1(1), 85–89.
10 M. I. Saleh, E. Kusrini, N. Ngah and B. M. Yamin, Acta Crys- 19 G. Brauer Hrsg, Handbuch der Präparativen Anorganischen
tallogr., Sect. E: Struct. Rep. Online, 2006, 62, o1654–o1656.
11 A. Hammerschmidt, I. Beckmann, M. Lage and B. Krebs,
Z. Anorg. Allg. Chem., 2005, 631(2), 393–396.
Chemie, Ferdinand Enke Verlag, Stuttgart, 1981, vol. 2,
p. 1013.
20 W. Schoniger, Mikrochim. Acta, 1955, 1, 123–129.
12 (a) V. O. Gelmboldt, E. V. Ganin, L. A. Koroeva, 21 G. M. Sheldrick, Acta Crystallogr., Sect. A: Fundam. Crystal-
M. S. Fonari, Yu. A. Simonov, V. Ch. Kravtsov and
logr., 2008, 64, 112–122.
This journal is © The Royal Society of Chemistry 2014
Dalton Trans.