A Discrete Dichloride Tetrahydrate Trapped by a Cyclopropenium Cation: Structure and Spectroscopic Properties

Article abstract of DOI:10.1002/cplu.202000146

A discrete dichloride tetrahydrate cluster, [Cl₂(H₂O)₄]^2?, was obtained as a salt of the bis(diphenylamino)diethylamino cyclopropenium cation [C₃(NPh₂)₂(NEt₂)]⁺ and characterized by single-crystal X-ray diffraction and infrared spectroscopy. This chloride–chloride ion-pair cluster consists of a [Cl₂(H₂O)₂]^2? square with opposite edges bridged by water molecules to give a chair-like structure of the non-hydrogen atoms. The solid-state structure is essentially the same as the calculated gas-phase structure. Infrared spectra were also collected on the deuterium analogue [Cl₂(D₂O)₄]^2?. Computational studies were carried out on gas-phase [Cl₂(H₂O)₄]^2? to confirm the infrared band assignments in the solid state. The structure and infrared spectrum are consistent with the discrete nature of the cluster.

Full text of DOI:10.1002/cplu.202000146

A Multidisciplinary Journal Centering on Chemistry
Accepted Article
Title: A Discrete Dichloride Tetrahydrate Trapped by a Cyclopropenium
Cation: Its Structure and Spectroscopic Properties
Authors: Owen John Curnow, Deborah L Crittenden, Mohammed
Abdelbassit, and Manuel Ferreras
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ChemPlusChem
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FULL PAPER
A Discrete Dichloride Tetrahydrate Trapped by a Cyclopropenium
Cation: Its Structure and Spectroscopic Properties
[a]
[a]
[a]
[a]
Mohammed S. Abdelbassit, Owen J. Curnow,* Manuel Ferreras and Deborah L. Crittenden*
2
–
–
Abstract: A discrete dichloride tetrahydrate cluster, [Cl
2
(H
2
O)
4
] , was
bonding between the Cl and dichloromethane in the extended
lattice.[10] In 2012, Wang et al. prepared a discrete [Cl
structure; although it exhibits strong Cl –π and
interactions with electron-deficient regions of the triazine rings.
Furthermore, Safin et al. claimed a discrete structure of dichloride
dihydrate, however, the cluster is in fact supported by four amino-
NH hydrogen bonds with H
2
O and Cl–.[12] We do not believe that
a cluster held together by hydrogen bonding should be described
as “discrete” when ignoring additional strong hydrogen bonds to
the cluster fragment.
(H
2
O)
O–π
]2–
obtained as
a
salt of the bis(diphenylamino)diethylamino
2
2
+
–
cyclopropenium cation [C
3 2 2
(NPh ) (NEt
2
)] and characterized by single
H
2
[
11]
crystal X-ray diffraction and infrared spectroscopy. This chloride-
2–
chloride ion-pair cluster consists of a [Cl
2 2 2
(H O) ]
square with
opposite edges bridged by water molecules to give a chair-like
structure of the non-hydrogen atoms. The solid state structure is
essentially the same as the calculated gas-phase structure. Infrared
2
–
spectra were also collected on the deuterium analogue [Cl
2
(D
2
O)
4
] .
2–
Computational studies were carried out on gas-phase [Cl (H
2
2
O)
4
] to
confirm the infrared band assignments in the solid state. The structure
and infrared spectrum are consistent with the discrete nature of the
cluster.
To the best of our knowledge there are only three solid-state
2
–
structures of the tetrahydrate [Cl
(H
2 2
O)
4
]
that have been
reported. The first one has prepared as the counterion of a
nickel(II) complex and is attached to the ligands through six NH--
–
[13]
-
2
Cl and four NH---OH hydrogen bonds. The second structure,
reported by Arunachalam and Ghosh, was formed in two bowl-
shaped tripodal receptors in an octahedral-like arrangement in
which all of the water molecules are disordered over two positions
Introduction
Chloride-water clusters are fundamentally-important motifs for
understanding a wide range of physicochemical processes in
nature. For example, they play a vital role in biological and
geological systems; particularly at water/membrane interfaces
and in the mobility of ions through ion channels, as well as in
electrical phenomena in the troposphere and ionosphere.[1]
Indeed, there are extensive theoretical studies on monochloride
and which consequently defies
a
reasonable structural
description. The structure is stabilized by multiple amide –NH
–
[14]
hydrogen bonding with Cl and H
reported by Chakraborty et al. in 2014 as a tetrabutylammonium
salt; the hydrated cluster is encapsulated in pyridyl-
2
O. The third structure was
a
functionalized receptor. Nevertheless, the structure shows strong
hydrogen bonding between the cluster and the receptor.[15] We
have previously reported the structure of a discrete dichloride
2 n
O)
]– clusters over the last several years.[2,3] On the
hydrate [Cl(H
other hand, there are only five reported ab initio studies on
2–
hexahydrate [Cl
2
(H
2
O)
6
i
]
cube with the triaminocyclopropenium
2
– [4–7]
dichloride hydrates [Cl
(H
2 2
O)
n
] .
Despite the expected ion-ion
+ [6]
(
TAC) cation [C
3
(NPr
2
)
3
] .
The larger dichloride-water
O)14]2–[17] have been
(H
2
repulsion between chloride ions, there is strong evidence for the
2–[16]
aggregates [Cl
2
(H
2
O)
8
]
and [Cl
2
–
–
formation of Cl ---Cl ion pairs in aqueous solution, particularly in
concentrated solutions.[4,5,8]
investigated in supramolecular systems as part of hydrogen-
O)10]2– has been
bonding networks. The decahydrate [Cl (H
obtained as one unit, but with strong hydrogen bonding to two
2
2
In 2013, Basu et al. synthesized the simplest hydrated
2–
dichloride cluster found to date, [Cl
2
(H
2
O)
2
] , by using an amide
O molecules, and
+
[18]
adjacent Na -water clusters.
Unfortunately, the vibrational
–
receptor. The Cl anions are bridged by two H
2
modes were not reported for any of these clusters due to
overlapping with the bands of the NH groups, except for the
the structure is stabilized by additional hydrogen bonds (two NH-
-OH (H O)
and two NH---Cl–).[9] [Cl ]2– was also reported by
Szumna et al. in 2001 as a co-crystal of a neutral octalactam
receptor with tetrabutylammonium chloride. The [Cl (H O)
]2–
-
2
2
2
2
[6]
dichloride hexahydrate. The vibrational modes of a limited
number of monochloride hydrates have been observed via Ar-
tagging at low temperature in the gas phase.[3]
2
2
2
cluster lies in a monocyclic cavity held via eight hydrogen bonds
Herein, we present a new hydrophobic environment,
–
(
four NH---OH
2
and four NH---Cl ). There is also hydrogen
+
[
C
3
(NPh
2
)
2
(NEt
2
)] , to host a discrete dichloride tetrahydrate
cluster. The crystal structure and the spectroscopic properties
2
–
2–
(
2 2 4 2 2 4
FT-IR) of [Cl (H O) ] and the [Cl (D O) ] analogue, as well as
a theoretical study, will be discussed.
[
a]
Mohammed S. Abdelbassit and A/Prof. Owen J. Curnow
Manuel Ferreras and Dr. Deborah L. Crittenden
School of Physical and Chemical Sciences
University of Canterbury, Private Bag 4800, Christchurch,
New Zealand
E-mail: owen.curnow@canterbury.ac.nz
deborah.crittenden@canterbury.ac.nz
Results and Discussion
Synthesis
Supporting information for this article is given via a link at the end of
the document.
We synthesized the new TAC cation diethylamino-
bis(diphenylamino)cyclopropenium, [C (NPh (NEt a
)]+, as
3
2
)
2
2
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2 3
chloride salt via the addition of a mixture of HNPh and NEt (3 :
Table
1.
Structure
refinement
data
for
4.5 molar ratio) to one equivalent of pentachlorocyclopropane
[C (NPh ) (NEt )]Cl.(H O) .
3
2
2
2
2
2
(
Scheme 1). Four cations were obtained: the ammonium salts
formula
a [Å]
b [Å]
c [Å]
α [°]
C
31
H
34ClN
3 2
O
[
[
H
C
2
NPh
(NEt
2
]Cl and [HNEt
3
]Cl along with two TAC-based salts
(NPh (NEt )]Cl, from which the latter
8.9507(3)
3
2
)
2
(NPh )]Cl and [C
2
3
2
)
2
2
11.4993(3)
14.6291(4)
68.871(3)
79.571(2)
89.225(2)
1379.10(7)
2
was ultimately isolated as a dihydrate in 41% yield. The
crystallization was carried out in a water-saturated binary solvent
of dichloromethane and ethyl acetate (1:1 v/v) at room
temperature. The [Cl
evaporation of a D O-saturated dichloromethane solution.
β [°]
γ [°]
V [Å ]
(D
2
O)
4
]2– analogue was prepared by
3
2
Z
ρ
2
calc [g cm–3
]
1.243
crystal system
space group
shape/colour
triclinic
P-1
colourless
crystal size [mm]
0.299 × 0.243 × 0.113
1.476
120(10)
μ [mm–1
T [K]
]
F(000)
548
2
θ range [°]
8.256 – 147.114
–11 ≤ h ≤ 11
index ranges
–
–
13 ≤ k ≤ 14
18 ≤ l ≤ 18
3 2 2 2
Scheme 1. Synthesis of [C (NPh ) (NEt )]Cl.
reflections collected
independent reflns
R(int)
data/restraints/parameters
GoF on F2
28951
5536
0.0304
5536/2/346
1.063
Single crystal structure
(NPh (NEt )]Cl.2H O crystallizes in the triclinic space group
P-1 (Table 1) in which the asymmetric unit consists of one cation
and a chloride dihydrate. In the cation, the phenyl groups exhibit
a propeller conformation to minimize the steric interactions
[
C
3
2
)
2
2
2
R
R
1
/wR
/wR
2
[I>2σ(I)]
(all data)
0.0429/0.1181
0.0469/0.1215
1.19/–0.47
1
2
Δρmax/min/e [Å–3
]
(
Figure 1).
The structural parameters for the cation are given in the
supplementary material. Bond distances indicate that the π
donation into the C ring from the diethylamino group is enhanced
3
by the presence of the electronegative phenyl groups. The
extended lattice shows that the cations form a short contact
through the phenyl groups (C36'---C36") of 3.135(3) Å (Figure 2),
which is found to be shorter than most “π-stacked” neutral arenes
at 3.3–3.8 Å.[19] This strong interaction can be attributed to the
substituent effects on the π-stacking geometry and thus the
formation of benzene dimers.[
20]
The chloride dihydrate forms a C
structure of [Cl (H O)
]2– which can be described as having a
square [Cl (H O)
]2– core with two additional terminal H
i
-symmetric dimeric
2
2
4
2
2
2
2
O
bridging molecules on opposite Cl---O edges. Folding about the
bridged edges produces a chair-like conformation (Figure 3).
Figure 1. The geometry and labeling scheme of the cation in
[C (NPh ) (NEt )]Cl·2H O. Hydrogen atoms are omitted for clarity.
3 2 2 2 2
Figure 2. Edge-to-edge π-stacking between two cations in
[C
3 2 2 2 2
(NPh ) (NEt )]Cl·2H O, C36'---C36" 3.135(3) Å. Hydrogen atoms are omitted
for clarity.
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2 2 4
Table 2. Structural parameters for [X (H O)
]2– (X = F, Cl) clusters.
Parameter
X-ray
Calculated
best estimate[
Calculated
range
HIMJUJ[13]
CIVGAR[15]
CIVGEV[15]
a]
[b]
X
Cl
Cl
Cl
Cl
Cl
F
O1---O2 [Å]
X–X [Å]
3.116(3)
5.0932(8)
3.191(2)
3.2900(16)
3.2250(17)
102.84(5)
77.16(5)
57.46(5)
62.86(5)
59.68(5)
29.38(7)
2.92
5.50
3.29
3.34
3.34
110.9
69.1
52.2
64.8
63.0
50.3
2.71 – 3.11
2.707(11)
5.175(4)
4.015(6)
3.172(6)
3.157(8)
109.7(2)
70.3(2)
4.456(3)
4.317(13)
3.251(2)
3.375(3)
3.317(3)
82.97(6)
97.03(6)
88.45(7)
44.72(5)
46.82(5)
17.41(6)
4.0067(7)
3.961(5)
2.647(7)
2.702(5)
2.618(6)
97.21(17)
83.79(17)
99.1(2)
5.09 – 5.97
X1---O1 [Å]
X1---O2 [Å]
X1A---O2 [Å]
X1–O2–X1A [°]
O2–X1–O2A [°]
O1–X1–O2 [°]
O2–O1–X1 [°]
O1–O2–X1 [°]
Fold angle [°]
3.17 – 3.44
3.14 – 3.62
3.13 – 3.59
--
--
--
--
--
--
42.24(18)
52.00(16)
85.8(2)
40.19(12)
40.73(14)
60.6(2)
40.4(3)
[
a]
[
b
]
[
2
1
]
M
P
2
/
a
u
g
-
c
c
-
p
V
D
Z
,
L
D
A
/
p
c
-
2
a
n
d
H
F
/
p
c
-
2
v
a
l
u
e
s
p
r
o
v
i
d
e
c
o
n
s
e
r
v
a
t
i
v
e
l
o
w
e
r
a
n
d
u
p
p
e
r
b
o
u
n
d
s
f
o
r
p
r
e
d
i
c
t
e
d
i
n
t
e
r
a
t
o
m
i
c
d
i
s
t
a
n
c
e
s
.
2 2 4
Cl (H O)
]2– clusters is available to date, but there is strong
[
computational evidence that such clusters can exist in
thermodynamically stable forms in the gas phase.[5,7] However,
previous studies have either failed to identify the C
i
-symmetric
cluster as a local minimum,[ or omit pertinent structural and
7]
spectroscopic data for this particular conformation.[ Although
5]
previous studies indicate that the C
global minimum in the gas phase, it is reasonable to expect that
the greater symmetry of the C cluster would be favoured during
crystal formation over the C -symmetric extended bridged
structures that would otherwise form to minimize ion-ion repulsion
in the gas phas. Ivanov et al. calculated that a C structure with a
i
-symmetric cluster is not the
i
1
1
]2– in [C
2 2 4 3 2 2 2 2
Figure 3. The structure of [Cl (H O) (NPh ) (NEt )]Cl·2H O. Dashed
lines indicate hydrogen bonds. The computationally optimized gas phase
structure is visually indistinguishable.
chain of three waters between the chlorides has the lowest-
energy gas-phase structure by 5.7 kcal/mol (CCSD(T)/aug-cc-
pVDZ) compared to the C structure, whereas a D4h-symmetric
i
structure with four bridging waters is 9.6 kcal/mol higher in energy
than the C1 structure.[5] Here we report predicted structural
2 2 4
Figure 4 depicts the environment around the [Cl (H O)
]2–
cluster. The cluster is sandwiched between two cyclopropenium
cations and supported by another two cations via weak hydrogen
bonds (C---O ~3.4 Å) between the water molecules within the
cluster and neighbouring aryl and methyl substituents (see Figure
parameters for the C-symmetric cluster in Table 2, along with
conservative computational error estimates for the interatomic
distance parameters. For reference, structural parameters for
i
2
–
other
crystallographically-characterized
[Cl (H O) ]
2
2
4
and
2
–
1
S for detailed illustration). Notably, the chloride anions are
located even further away from the centers of the cyclopropenium
rings (Cl---C = 3.48 Å). Each chloride anion engages in six
[F (H O) ] non-discrete clusters have also been extracted from
2
2
4
the literature data.[13,15]
3
hydrogen bonds; three of them are strong Cl---HO hydrogen
bonds within the cluster (3.19 – 3.29 Å) and three are weak Cl---
HC aryl hydrogen bonds to the surrounding cations (3.64 – 3.67
Å). This contrast between strong intra-cluster hydrogen bonding
and weak interactions with the surrounding cyclopropenium units
provides strong evidence for the existence of a discrete dichloride
tetrahydrate structure within the crystalline environment.
If the cluster we have identified is truly discrete, then it should
be stable or at least semi-stable in the gas phase. To the best of
our knowledge, no direct experimental evidence for gas phase
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Comparison with other literature structures reveals that much
larger differences are observed if the cluster forms additional
bonds with surrounding molecules. Kopylovich et al. synthesized
similar structures of a hexameric water cluster (H
dichloride tetrahydrate [Cl (H O)
]2– (CSD reference code
HIMJUJ), which contain a square core of (H
respectively, with two additional H
2 6
O) and a
2
2
4
2
–
2
O)
4
2 2 2
and [Cl (H O) ] ,
O molecules.[ Their structure
13]
2
is similar to the one reported here, and consistent with gas phase
computational data except for the extended Cl---O1 distance of
4.02 Å, which arises from the fact that the terminal or “outer” water
does not form a hydrogen bond back to chloride but instead
hydrogen bonds to a neighbouring pyridine ring (N---O = 2.81 Å).
2 2 4
(H O)
]2–
Chakraborty et al. reported the structures [Cl
CIVGAR) and [F (H O)
]2– (CIVGEV),[15] but these clusters are
(
2
2
4
even less discrete than those reported by Kopylovich et al. Both
are stabilized by strong (amide)-NH hydrogen bonding from the
–
receptor to Cl and H
2
O. Notably, the terminal water molecules
hydrogen bond to both the pyridine ring in the receptor and the
chloride ions, which prevents them interacting with the central
water molecules (O---O = 4.46 Å).
2 2 4 3 2 2 2 2
Figure 4. The environment of [Cl (H O) (NPh ) (NEt )]Cl.2H O
]2– in [C
Hydrogen atoms are omitted for clarity.
Further evidence that our crystallographically-trapped cluster
resembles its gas phase counterpart lies in the close agreement
between computed and observed intermolecular bonding angles,
which agree to within 10° for our system but differ substantially in
others.
At first glance, the ~20° difference between fold angles that
the terminal water molecule subtends to the central dichloride
dihydrate square appears to contradict the otherwise close
agreement between computed gas phase structural parameters
and their experimentally observed X-ray structure counterparts.
However, this hinge angle is particularly soft and therefore can be
easily influenced by crystal-packing effects.
Direct comparison of computed and observed structural
parameters is not generally straightforward, because differences
between them can be attributed to a combination of physical
effects (crystal packing, thermal and zero-point vibrational
motion) and computational artefacts (errors associated with
choice of electronic structure method and basis set
incompleteness) that cannot be disentangled. Nonetheless, it is
]2– structure reported here resembles
clear that only the [Cl (H O)
2 2 4
its gas phase counterpart, according to the parameters reported
in Table 2. For all intra-cluster distances, our observed values fall
within the computed upper and lower bounds, although they are
not in perfect agreement with the best computational estimates.
This implies that crystal packing and nuclear vibrational effects
are of approximately the same magnitude as computational
method uncertainties.
Infrared spectroscopy
Vibrational spectroscopy provides detailed information about
bonding within and around solvated ion complexes,[
22]
and
therefore is an ideal technique to probe the discreteness of the
dichloride tetrahydrate captured here.
Table 3. Experimental and calculated anharmonic vibrational frequencies (in
–1
2–
2–
Mid-IR spectra were recorded for [C
and its deuterated analogue [C (NPh
3
(NPh
(NEt
2
)
2
(NEt
)]Cl.2D
2
2
)]Cl.2H
O, and
2
O
cm ) for [Cl
2
(H
2
O)
4
]
2 2 4
and [Cl (D O) ]
3
2
)
2
2
Solid-state
experimental
Gas phase
Deuterated
experimental
Assignment
subtracted from one another to suppress bands arising from the
cyclopropenium units and isolate peaks arising from the dichloride
tetrahydrate clusters. The stretching region of the resultant
difference spectrum is illustrated in Figure 5, superimposed with
computationally predicted line spectra illustrating both predicted
band centres and relative intensities. The band patterns for the
isotopomers are identical, but shifted due to isotopic mass effects.
Experimental and computational band centres are reported in
calculated[
3541
a]
3632
2677
–
ν(asym, syn)
ν(asym, anti)
ν(sym, outer)
ν(sym, inner)
2ν(bend, outer)
2ν(bend, inner)
ν(bend, outer)
ν(bend, inner)
–
3516
3470
3405
3310
3250
1655
1625
3460
2583
2504
2453
2394
1225
1198
3409
Table 3. Analysis of the bending region reveals two bending
3357
bands – a strong band at 1625 cm–1 (1198 cm–1 for deuterated
–
1
–1
isotopologue) and a much weaker band at 1655 cm (1225 cm
3192
for deuterated isotopologue). This immediately helps identify and
assign the peaks at 3250 cm–1 and 3310 cm–1 as bending
overtones. Although these bands formally have zero intensity in
harmonic frequency calculations, their predicted positions are
indicated by dots at appropriate positions along the x axis.
1679
1596
[a]
Frequencies computed at MP2/aug-cc-pVDZ with empirical anharmonic
correction applied.
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⦁
⦁
Figure 6. Fundamental stretching and bending vibrational modes of dichloride
tetrahydrate.
In either case, the differences are small, and inconsequential.
The close agreement between computationally-predicted
anharmonic gas phase transition frequencies and observed solid
state IR band centres provides strong evidence that we have
isolated a discrete dichloride tetrahydrate structure, encapsulated
predominantly through steric confinement, i.e. exhibiting only
weak interactions with its surrounding environment.
Figure 5. FT-IR spectrum of [C
3
(NPh
2
)
2
(NEt
2 2
)]Cl.2H O minus the spectrum
of [C (NPh (NEt )]Cl.2D O, with
3
)
2 2
2
2
a
superimposed computational line
spectrum for the hydrogenated species.
To make further progress in assigning the observed spectrum,
we turn to the computational results reported in Table 3 and
Conclusions
illustrated in Figure 6. A pair of high frequency asymmetric
stretching modes separated by ~ 20 cm–1 are expected, but only
We have illustrated the first example of a discrete dichloride
tetrahydrate, [Cl (H O) ] , in the solid-state by taking advantage
2 2 4
2–
one is observed. It is assigned to the fundamental stretching
mode that undergoes the largest change in dipole moment;
ν(asym, syn). It is most likely that the nearby lower-intensity
ν(asym, anti) fundamental is simply subsumed into the band
of the weak interactions between anions and triamino-
cyclopropenium cations. The vibrational modes of a discrete
chloride hydrate species have been observed and assigned for
the first time in the solid state. In addition, we have also reported
the optimized structure and the calculated IR-active vibrational
–
1
centred at 3632 cm .
The two symmetric stretching fundamentals at 3470 cm–1 and
2–
405 cm–1 are easy to identify and assign, because the
frequencies of [Cl
2
(H
2
O)
4
]
in the gas-phase which are in
3
excellent agreement with the solid state structure and the
experimental infrared spectrum.
experimental band centres align closely with their
computationally-predicted values.
The highest intensity bending mode corresponds to the in-
phase bending of the two “inner” water molecules within the
square planar dichloride dihydrate core. Both the fundamental
and overtone bands are clearly visible in the difference spectrum
Experimental Section
–
1
at 1625 and 3250 cm , respectively. Bending of the outer water
molecules causes a much smaller change in dipole moment of the
dichloride tetrahydrate cluster as a whole, so the ν(bend, outer)
fundamental has a much lower transition intensity and is observed
All the experimental work and sample preparation were carried out under
dried nitrogen atmosphere using standard Schlenk techniques. CH
2 2
Cl ,
diethylether, ethylacetate, D O, triethylamine and diphenylamine were
2
obtained commercially. Solvents were dried using an in-house solvent
purification system.
–
1
as a very weak band at 1655 cm . Its overtone is barely visible
–
1
and only shows up as a very weak shoulder at 3310 cm .
A few small discrepancies between theory and experimental
exist; ν(bend, outer) appears to be slightly overestimated by all
computational approaches employed here and ν(asym, syn)
underestimated. Unlike for the structural parameters, we have not
attempted to provide bounds for the predicted anharmonic
frequencies, so it is certainly plausible that these remaining
discrepancies are computational artefacts. However, it is also
possible that crystal packing and thermal effects that we have not
attempted to account for here could account for the residual
differences between computational predictions and experimental
observations.
TGA/DSC data were collected on dried samples using a TA Instruments
SDT Q600 at 10 °C min . Mid-IR data were collected at room temperature
by using a Vertex 70 FT-IR spectrometer from Bruker (Germany),
operating with a Platinum ATR unit with a diamond crystal. A resolution of
4 cm–1 and 16 scans were taken. Microanalyses were performed by
Campbell Microanalytical Laboratory, University of Otago, Dunedin.
–1
Diethylaminobis(diphenylamino)cyclopropenium chloride dihydrate
[
C
3
(NPh
A solution of HNPh
in CH Cl (75 mL) was added slowly to a solution of C Cl H (4.14 g, 19.46
2
)
2
(NEt
2
)]Cl.2H
2
O
2
(9.87 g, 58.37 mmol) and NEt
3
(12.2 mL, 87.56 mmol)
2
2
3
5
mmol) in CH
reaction mixture was stirred overnight at ambient temperature. CH
removed in vacuo to give a dark-brown liquid. ES-MS shows the presence
2
Cl
2
(50 mL) and cooled to 0 °C. After stirring for 1h, the
2
Cl was
2
+
+
+
+
of [HNEt
HNEt ]Cl was filtered off after precipitation by the addition of acetone (75
mL). [H NPh ]Cl and [C (NEt (NPh )]Cl salts were separated by column
3 2 2 3 2 2 2 3 2 2 2
] , [H NPh ] , [C (NEt ) (NPh )] and [C (NPh ) (NEt )] .
[
3
2
2
3
2
)
2
2
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chromatography using silica-gel 60G and CH
2
Cl
2
-ethylacetate (1:1 v/v) as
(NPh (NEt )]Cl and
the solvent was removed in vacuo to give a pale yellow solid. Undried
CH Cl -ethylacetate (1:1 v/v) was used for crystallization, and slow
113, 5259-5272; g) W. Punyain, K. Takahashi, Phys. Chem. Chem. Phys.
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the mobile phase. Ethanol was then used to elute [C
3
2
)
2
2
2006, 125, 133206; i) W. H. Robertson, M. A. Johnson, Annu. Rev. Phys.
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Guo, J. Chem. Phys. 2018, 148, 064305.
2
2
evaporation at ambient temperature gave pale yellow plates (3.54 g, Yield
1
CN): δ = 0.88 (t, 3J(H,H) = 7.04 Hz, 2H;
4
NCH
1
4
1
1%). H NMR (400 MHz, CD
3
3
2
CH
0H; NC
6.77 (NCH
42.83 (NC
ClO
3
), 2.76 (q, J(H,H) = 7.04 Hz, 3H; NCH
2
CH
): δ = 13.54 (NCH
) ring, 114.47, 127.22, 129.66,
3
), 7.16-7.34 ppm (m,
H
6 5
). 13C{ H} NMR (100 MHz, CDCl
1
3
2
CH ),
3
[
3] a) P. Ayotte, S. B. Nielsen, G. H. Weddle, M. A. Johnson, S. S. Xantheas,
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2
CH
). EI-MS: Found m/z 445.2490 [M ]; Calcd 445.2490 [M ].
2
: C, 72.70; H, 6.65; N, 8.14; Found: C, 73.08; H, 6.46; N,
3
), 122.31, 124.30 (C
3
+
+
6
H
5
C
31
H
34
N
3
8
.13.
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[
C
3
(NPh
.162 mmol) was dissolved in dry CH
Cl was then removed in vacuo. Dry diethylether
20 mL) was added to the mixture under nitrogen and kept overnight at
ambient temperature. The excess diethylether and D O were then
removed in vacuo to give colourless crystals of the desired product (1.4 g,
5% yield).
2
)
2
(NEt
2
)]Cl(D
2
O)
2
.
Anhydrous [C
3
(NPh
2
)
2
(NEt
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Cl (30 mL). D
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2
O (0.2 mL, 10 mmol)
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2
2
7
(
[
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2012, 41, 11765-11775.
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1
1
2
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refinement package[24] using Least Squares minimisation with anisotropic
thermal parameters for all non-hydrogen atoms. Hydrogen atoms on the
methylene groups were refined isotropically at their calculated positions
and methyl groups were refined as rotating groups. The water protons
were located from the density difference map and refined isotropically.
CCDC-1981447 contains the supplementary crystallographic data for this
paper. This data can be obtained free of charge from The Cambridge
Crystallographic Data Centre.
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2 2 4
Geometries of gas-phase [Cl (H O)
]2– clusters were optimised at
[
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HF/pc-2, HFS/pc-2, and MP2/aug-cc-pVDZ, and harmonic
vibrational frequencies computed at MP2/aug-cc-pVDZ. An
empirical quadratic correction model was applied to obtain
predicted anharmonic vibrational frequencies.[25] All ab initio
calculations were performed using the NWChem program
package.[26]
[
[
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2
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Acknowledgements
Dr. Matthew I. J. Polson (University of Canterbury) is thanked for
his assistance with the X-ray crystallography.
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[
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4
Keywords: dichloride • hydrate • infrared • solvate • X-ray
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Puschmann, J. Appl. Cryst. 2009, 42, 339-341.
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[
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A discrete dichloride
tetrahydrate trapped in a
hydrophobic
Mohammed S. Abdelbassit, Owen J. Curnow,* Manuel
Ferreras and Deborah L. Crittenden*
environment
A
phenyl-based
triaminocyclopropenium
cation
crystallizes with
a
discrete dichloride tetrahydrate
cluster. The structure and infrared spectrum agree well
with gas-phase calculations, and thus confirm the
discreteness of the cluster. It can be viewed as a
chloride-chloride ion pair bridged by two waters to form
a square, with two additional waters added across
opposite edges to give an overall structure with a chair-
like conformation.
Page No. – Page No.
A Discrete Dichloride Tetrahydrate Trapped by a
Cyclopropenium Cation: Its Structure and Spectroscopic
Properties
[
a]
Mohammed S. Abdelbassit and A/Prof. Owen J. Curnow
Manuel Ferreras and Dr. Deborah L. Crittenden
School of Physical and Chemical Sciences
University of Canterbury, Private Bag 4800, Christchurch,
New Zealand
E-mail: owen.curnow@canterbury.ac.nz
deborah.crittenden@canterbury.ac.nz
Supporting information for this article is given via a link at the
end of the document.
Entry for the Table of Contents
This article is protected by copyright. All rights reserved.