Remote halogen switch of amine hydrophilicity

Article abstract of DOI:10.1039/c2ce25401h

Bromide and iodide anions switch hydrogen-bonding patterns in otherwise isostructural dimethanol solvates N-methyl-1,4-diazabicyclo[2.2.2]octanium bromide (dabcoCH₃Br·2CH₃OH) and analogous iodide (dabcoCH₃I·2CH₃OH), both synthesized in the high-pressure version of the Menshutkin reaction at 1.2 and 2.4 GPa, respectively. The magnitudes of the high pressure triggering these reactions correspond to identical molecular volumes of both solvates. This journal is

Full text of DOI:10.1039/c2ce25401h

View Article Online / Journal Homepage / Table of Contents for this issue
Dynamic Article Links
CrystEngComm
Cite this: CrystEngComm, 2012, 14, 6374–6376
www.rsc.org/crystengcomm
COMMUNICATION
Remote halogen switch of amine hydrophilicity{
Michał Andrzejewski, Anna Olejniczak and Andrzej Katrusiak*
Received 21st March 2012, Accepted 22nd June 2012
DOI: 10.1039/c2ce25401h
+
Bromide and iodide anions switch hydrogen-bonding patterns
in otherwise isostructural dimethanol solvates N-methyl-1,4-
diazabicyclo[2.2.2]octanium bromide (dabcoCH Br?2CH OH)
3
amine group of dabcoCH is either involved or excluded as the
H-acceptor, respectively (Scheme 1).
Both the solvates were obtained in pressure-promoted reactions:
3
3
3 3
and analogous iodide (dabcoCH I?2CH OH), both synthesized
pT
:
dabcoHXz3CH3OH À? dabcoCH3X CH3OHzH2O (1)
in the high-pressure version of the Menshutkin reaction at 1.2
and 2.4 GPa, respectively. The magnitudes of the high pressure
triggering these reactions correspond to identical molecular
volumes of both solvates.
where p is the reaction triggering pressure, 1.2 GPa for X = Br
T
and 2.4 GPa for X = I.
At ambient conditions, unsolvated dabcoCH
3
I was obtained in
the reaction of dabco with CH I, and is applied as a structure-
3
The chemical properties of bromide and iodide anions are either
similar and characteristic of halogens, or drastically different. In
2
9
directing agent in zeolite syntheses. Other quaternary-amine salts
of dabco such as 1-butyl-4-aza-1-azoniabicyclo[2.2.2]octane chlor-
polar solvents anion I is a strong nucleophile and weak base,
1
0
2
while Br has comparative nucleophilic and basic properties. In
ide, are ionic catalysts for Baylis–Hillman reactions. Both these
2
radical reactions Br and I act differently too, as described by the
2
reactions are examples of the quaternization of tertiary amines
1
1
1
Kharasch effect. Furthermore, crystalline HBr is ferroelectric, and
from alkyl halides known as the Menshutkin reaction, which
2
HI is not. It was shown recently that in 1,4-diazabicyclo[2.2.2]oc-
proceeds according to an S 2 mechanism. To our knowledge, no
N
dabcoCH
3
Br syntheses and applications have been reported.
tane (dabco) hydrobromide (dabcoHBr) hydrogen bonds
+
…
+
…
2
NH N and NH Br can be interconverted by applying
The crystals of dabcoCH Br?2CH OH and dabcoCH I?
3
3
3
12
3
temperature and pressure, while in all ten polymorphs of dabco
2CH OH are less isostructural than would appear from their
3
+
…
4
formulae, identical except for exchanged homovalent halogen
hydroiodide (dabcoHI) only NH N bonds are present. Phase
III of dabcoHBr and phase V of dabcoHI are isostructural and
they both exhibit giant dielectric response, coveted for electronic
anions, with the same space-group symmetry, similar unit-cell
+
2 2
dimensions and similarly located dabcoCH3 and Br /I ions
(Fig. 1).{ However, despite having the same solvent-accessible
volume (Fig. 2), the hydrogen-bonding patterns and positions of
5,6
applications.
However, there are no structural similarities
whatsoever between dabcoHBr phases I and II and dabcoHI
7
phases I, II, III, IV, VI, VII, VIII and IX. Properties of specific
methanol molecules are distinctly different. The most striking
…
3 3
difference is that in dabcoCH I?2CH OH one methanol is OH N
functional groups, and in particular their intermolecular and
interionic aggregation, are fundamental for molecular biology and
chemistry in general. Predictable behaviour of compounds and
their functional groups are essential for understanding all dynamic
processes, like those in living tissue, membrane transport or
transformable molecules and aggregates. Here we report an
+
3
hydrogen bonded to the tertiary amine N(4) of dabcoCH , while
2
2
indirect effect of Br and I anion switching of the hydrophilic
and hydrophobic behaviour of a tertiary amine group. This
phenomenon has been monitored in isostructural solvates of
N-methyl-1,4-diazabicyclo[2.2.2]octanium iodide dimethanol
8
OH) and N-methyl-1,4-diazabicy-
(
denoted dabcoCH I?2CH
3
3
clo[2.2.2]octanium bromide dimethanol (dabcoCH Br?2CH OH)
3
3
with notably different H-bonding patterns, where the tertiary
Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6,
6
0-780, Pozna n´ , Poland. E-mail: katran@amu.edu.pl;
Fax: +48(61)8291505; Tel: +48(61)8291443
Electronic supplementary information (ESI) available: Details of high
{
16–21
pressure experiments
and structure descriptions. CCDC reference
Scheme 1 Hydrogen-bonding patterns in dabcoCH
3 3
I and dabcoCH Br
numbers 869507–869511. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/c2ce25401h
methanol solvates.
6
374 | CrystEngComm, 2012, 14, 6374–6376
This journal is ß The Royal Society of Chemistry 2012

View Article Online
3 3
in dabcoCH Br?2CH OH this amine does not form any hydrogen
bonds (Fig. 1, Scheme 1). The apparent structural difference
…
between these solvates, connected to the formation of OH
bonds, is the reverse orientation of methanol molecules. In
dabcoCH Br?2CH OH one methanol molecule is disordered and
N
3
3
…
alternatively OH Br bonded to two Br anions; this methanol
2
2
…
also acts as the H-acceptor in an OH O bond to the other
methanol molecule (Fig. 1). In dabcoCH I?2CH OH one metha-
3
3
…
3
nol molecule C(1M)H O(1M)H is O(1M)H(1M) N(4) bonded to
the cation only, and the other methanol molecule
…
2
C(2M)H O(2M)H forms only one O(2H)H
3
I
bond. Thus in
dabcoCH I?2CH OH there are two separate differently H-bonded
3 3
aggregates: CH OH dabcoCH , and CH OH I .
…
+
3
…
2
3
3
It is remarkable that in both dabcoCH
3
2
X?2CH
3
OH solvates the
…
interionic N1 N1, N4 N4, and X N1/N4 distances are
…
…
2
…
2
˚
distances differ by over 1.5 A.
nearly identical, while the X
2
X
The contacts of larger I anions and methyl C(7)H are about
3
˚ ˚
.7 A shorter than the sum of the van der Waals radii (1.2 A for H,
0
2
2
13
˚ ˚
1.85 A for Br and 1.98 A for I according to Bondi ), while
2
analogous distances of the smaller Br
anion in
˚
dabcoCH Br?2CH OH are about 0.1 A longer than the sum of
3 3
the van der Waals radii (Table S2 in the ESI{).
We attempted to destabilize the H-bonding patterns in the
solvates by changing the pressure of dabcoCH
between 1.0 and 2.4 GPa, and of dabcoCH Br?2CH OH between
.2 and 1.7 GPa. However, in both these pressure ranges the
3 3
I?2CH OH
3
3
1
structures compressed monotonically and their H-bonding pat-
terns remained unaffected. It was found that the two pressure
magnitudes triggering the N-methylation reaction compress the
3
˚
solvates to approximately equal formula-unit volumes of 288 A
Fig. 1 Structures of (a) dabcoCH
CH OH, both at 1.2 GPa and projected down [010]. Hydrogen bonds are
indicated by dotted lines. Two sites of disordered O(1M)H(1M) methanol
atoms in dabcoCH Br?2CH OH are superimposed in this projection.
3
Br?2CH
3
OH and (b) dabcoCH
3
I?
calculated as the unit-cell volume divided by the number of
2
3
formula units, as shown in Fig. 3. At the same pressure of 1.2 GPa,
3
˚
the formula unit of dabcoCH
than that of dabcoCH I?2CH
smaller than the molecular-volume difference between dabcoHI
3
Br?2CH
3
OH is smaller by ca. 17 A
3
3
3
3
OH. This volume difference is
4
3
3
˚
and dabcoHBr at 0.1 MPa/296 K, equal to 27 A , but nearly
identical to that at 0.4 GPa.
Fig. 2 Solvent-accessible volumes in the structures of (a)
dabcoCH Br?2CH OH and (b) dabcoCH I?2CH OH at 1.2 GPa
calculated by the Mercury program without the methanol molecules in
Fig. 3 The formula-unit volume V/Z (Table S1{) as a function of
pressure for dabcoCH I?2CH OH and dabcoCH Br?2CH OH. The lines
3 3 3 3
3
3
3
3
14
˚
the structure. The probing radius of 0.5 A yielded similar void volumes of
joining the points have been drawn to guide the eye. p is the methylation
T
3
˚
107.9 and 107.3 A per unit cell (19.0 and 17.6%), respectively.
triggering pressure (eqn (1)).
This journal is ß The Royal Society of Chemistry 2012
CrystEngComm, 2012, 14, 6374–6376 | 6375

View Article Online
It appears that the hydrophilic behaviour of the tertiary
amine in dabcoCH I?2CH OH and hydrophobic behaviour in
dabcoCH Br?2CH OH is due to a weaker affinity of the I
Acknowledgements
3
3
2
This study was supported by the Foundation for Polish
Science, TEAM project 2009-4/6. A. O. acknowledges the
receipt of a scholarship START from the Foundation for
Polish Science in 2012.
3
3
2
anions to the hydroxyl H-atoms of methanol than that of Br .
2
Hence, I binds to one methanol molecule and the other
+
…
methanol is OH N bonded to the dabcoCH cation. In
3
2
dabcoCH Br?2CH OH the Br anion attracts both the
3
3
methanol molecules in this way so that one methanol molecule
Notes and references
…
2
is directly OH Br bonded, and the other methanol is OH O
…
{ Crystal data for: dabcoCH
869507), monoclinic space group P2
3
Br?2CH
3
OH at 296 K/1.2 GPa (CCDC
…
˚
/m, a = 9.270(2) A, b = 6.7304(13) A, c
˚
23
bonded to the first mediating methanol. The CH OH
3
1
3
…
2
CH )OH Br aggregates engage all the hydroxyl H-donors
= 9.710(4) A, b = 107.60(4)u, V = 577.5(3) A , Z = 2, D = 1.560 g cm ,
˚
˚
(
3
2
GOF on F 1.167, R
.7 GPa (869508), monoclinic space group P2
6.653(3) A˚ , c = 9.643(9) A˚ , b = 107.72(7)u, V = 561.9(6) A˚ , Z = 2, D =
1
(all data) = 0.0984; dabcoCH
3 3
Br?2CH OH at 296 K/
and consequently no H-bond can be formed to the tertiary
+
amine of dabcoCH3 . Thus this final effect can be associated
˚
1
1
/m, a = 9.194(4) A, b =
3
2
3
2
1
.603
dabcoCH
P2 /m, a = 9.059(3) A, b = 6.7868(17) A, c = 10.543(4) A, b = 108.28(3)u, V
615.5(3) A , Z = 2, D = 1.717 g cm , GOF on F 1.178, R
0.0277; dabcoCH I?2CH OH at 296 K/1.2 GPa (869510), monoclinic space
group P2 /m, a = 9.040(3) A, b = 6.7590(9) A, c = 10.516(3) A, b =
08.45(3)u, V = 609.5(3) A , Z = 2, D = 1.734 g cm , GOF on F 1.676, R
all data) = 0.0486; dabcoCH I?2CH OH at 296 K/2.4 GPa (869511),
monoclinic space group P2 /m, a = 8.879(3) A˚ , b = 6.6161(9) A˚ , c =
g
cm
,
GOF on
F
1
1.137, R (all data) = 0.1801;
with the competition between the H-acceptors of the methanol
2
hydroxyl (this H-bonded to Br ) and amine N(4).
3
I?2CH
3
OH at 296 K/1.0 GPa (869509), monoclinic space group
˚
˚
23
˚
1
3
2
Our survey of the Cambridge Structural Database (version
˚
=
1
(all data) =
1
5
1
.14) revealed five crystal structures (refcodes: UNICIC,
3
3
˚
˚
˚
1
DAJVIV, VIBQUT, YASLOU, HUWLAN) containing the
2
Br anion and two methanol molecules hydrogen-bonded exactly
3
23
2
˚
1
1
(
3
3
as in dabcoCH Br?2CH OH (Scheme 1), whereas only one
3
3
1
3
23
˚
˚
1
0.328(3) A, b = 108.81(3)u, V = 574.3(2) A , Z = 2, D = 1.840 g cm ,
structure of an analogous aggregate involving the iodide anion
has been found (refcode WEPLEI). In this only aggregate of the
2
1
GOF on F 1.394, R (all data) = 0.0590.
2
I
2
anion, one methanol molecule forms bifurcated bonds to I
1
M. S. Kharash and F. R. Mayo, J. Am. Chem. Soc., 1933, 55,
468–2496.
2 S. W. Ciechanowski and R. H. Cole, J. Chem. Phys., 1973, 59,
and the second methanol molecule. We have also found 4 solvate
…
2
crystals where methanol is OH N bonded to an amine nitrogen
2
2
2420–2426.
in the presence of a Br anion, and 4 structures with I anions.
There are no isostructural relations between any of those
3
A. Budzianowski and A. Katrusiak, J. Phys. Chem. B, 2006, 110,
755–9758.
4 A. Olejniczak, A. Katrusiak and M. Szafra n´ ski, Cryst. Growth Des.,
010, 10, 3537–3546.
M. Szafranski and A. Katrusiak, J. Phys. Chem. B, 2008, 112,
779–6785.
9
structures, analogous to those between dabcoCH
and dabcoCH I?2CH OH.
The effect of hydrophobic and hydrophilic behaviour of the tertiary
amine in dabcoCH Br?2CH OH and dabcoCH I?2CH OH solvates
can be attributed to the balance between affinities of anions and the
3 3
Br?2CH OH
2
3
3
5
6
3
3
3
3
6 M. Szafranski, J. Phys. Chem. B, 2009, 113, 9479–9488.
7 W. Nowicki, A. Olejniczak, M. Andrzejewski and A. Katrusiak,
CrystEngComm., 2012, 14, DOI: 10.1039/C2CE25359C.
+
tertiary amine of dabcoCH
3
to hydroxyl H-atoms of methanol
8
9
A. Olejniczak and A. Katrusiak, CrystEngComm, 2010, 12, 2528–2532.
T. Talewaki, L. W. Beck and M. E. Davis, Microporous Mesoporous
Mater., 1999, 33, 197–207.
molecules, the only H-donors in these solvates. The hydrogen
bonding pattern can also be due to the difference in anionic radii
2
1.96 A for Br and 2.20 A for I , according to Goldschmidt).
2
10 Y. Cai, Y. Liu and G. Gao, Monatsh. Chem., 2007, 138, 1163–1166.
1 M. B. Smith and J. March, in March’s Advanced Chemistry. Reactions,
˚
˚
(
1
The resemblance of structures dabcoCH Br?2CH OH and
3
3
Mechanism, and Structure, 6th edn, Wiley, New Jersey, 2007, ch. 10.
12 L. Fabian and A. Kalman, Acta Crystallogr., Sect. B: Struct. Sci., 2004,
3 3
dabcoCH I?2CH OH arises from the fact that the methanol
6
0, 547–558.
3 A. Bondi, J. Phys. Chem., 1964, 68, 441–451.
4 C. F. Macrae, I. J. Bruno, J. A. Chisholm, P. R. Edgington, P. McCabe,
molecule in reversed orientations occupies similar volume and
requires no symmetry changes. Hence, despite different
H-bonding patterns, similar anions, the same cations and
methanol molecules are similarly packed in the compressed
crystal space. Therefore the different H-bonding patterns can be
associated with the anions only, and not with the influence of
the crystal environment. On the other hand, the modified
H-bonding pattern considerably affects the crystal packing and
unit-cell dimensions. To our knowledge this is the first report on
1
1
E. Pidcock, L. Rodriguez-Monge, R. Taylor, J. van de Streek and P. A.
Wood, J. Appl. Crystallogr., 2008, 41, 466–470.
5 F. R. Allen, Acta Crystallogr., Sect. B: Struct. Sci., 2002, 58, 380–388.
1
1
1
6 L. Merrill and W. A. Bassett, Rev. Sci. Instrum., 1974, 45, 290–294.
7 (a) G. J. Piermarini, S. Block, J. D. Barnett and R.A. Forman, Appl.
Phys., 1975, 46, 2774–2778; (b) H. K Mao, J. Xu and P. M. Bell, J.
Geophys. Res., 1986, 91(B5), 4673–4676.
8 A. Budzianowski, A. Katrusiak, in High-pressure Crystallography, ed.
A. Katrusiak and P. McMillan, Kluwer, Dordrecht, 2004, pp. 101–112.
19 Oxford Diffraction CryAlisCCD, Data collection GUI for CCD and
CrysAlisRED, CCD data reduction GUI versions and 1.17.13 beta,
Oxford Diffraction, Poland, 2003.
1
2
2
a remote Br and I anion exchange effect switching the
H-bonding pattern involving a tertiary amine. It shows that the
hydrophilicity effect of ions can be considerably longer in range
than is currently believed, and that the ions do not have to be
directly involved in the hydrogen bonds that they modify.
2
2
0 A. Katrusiak, Z. Kristallogr., 2004, 219, 461–467.
1 G. M. Sheldrick, Acta Crystallogr., Sect. A: Found. Crystallogr., 2008,
64, 112–122.
6
376 | CrystEngComm, 2012, 14, 6374–6376
This journal is ß The Royal Society of Chemistry 2012