Structure and properties of the sodium, potassium and calcium salts of 2-(2,3-dimethylphenyl)aminobenzoic acid

Article abstract of DOI:10.1016/j.molstruc.2010.02.045

The mefenamic acid sodium, potassium, and calcium salts with general formulae [Na(mef)(H₂O)₂]_n·nH₂O, [K(mef)(H₂O)]_n and [Ca(mef)₂(H₂O)₂]_n·nH

Full text of DOI:10.1016/j.molstruc.2010.02.045

Journal of Molecular Structure 970 (2010) 79–89
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Structure and properties of the sodium, potassium and calcium salts
of 2-(2,3-dimethylphenyl)aminobenzoic acid
Rafal Kruszynski a, , Agata Trzesowska-Kruszynska , Piotr Majewski , Ewa Łukaszewicz ,
a
b
b
*
b
a
a
Kamila Majewska , Tomasz Siera n´ ski , Bartłomiej Lewi n´ ski
a
Institute of General and Ecological Chemistry, Technical University of Lodz, Zeromskiego 116, 90-924 Lodz, Poland
Institute of Organic Chemistry, Technical University of Lodz, Zeromskiego 116, 90-924 Lodz, Poland
b
a r t i c l e i n f o
a b s t r a c t
Article history:
The mefenamic acid sodium, potassium, and calcium salts with general formulae [Na(mef)(H O) ] ꢀnH O,
2
2 n
2
Received 21 November 2009
Received in revised form 12 February 2010
Accepted 15 February 2010
Available online 19 February 2010
1
[K(mef)(H
2
O)]
n
and [Ca(mef)
(H
2 2
O)
2
n
] ꢀnH
2
O have been synthesised, studied by X-ray crystallography, H
13
and C NMR and IR spectroscopy. The complex salts are air stable and soluble in water. During heating
the Na and K complexes melt in the complexed water and next recrystallise in anhydrous form. In the
solid state all salts create one-dimensional coordination polymers. The central atoms are five, six and
seven coordinated, respectively, for Na, K and Ca complexes. In all structures exist OAHꢀ ꢀ ꢀO, NAHꢀ ꢀ ꢀO
and CAHꢀ ꢀ ꢀO hydrogen bonds. The vibrational analysis has been carried out for mefenamic acid and its
three coordination polymer compounds on the basis of experimental results as well as quantum mechan-
ical calculations. The theoretical and experimental vibrational frequencies are similar and reveal charac-
teristic vibrations for all IR active oscillators. In the IR spectra of salts exist strong bands at ca. 1365 and
Keywords:
Mefenamic acid
Sodium
Potassium
Calcium
ꢁ1
Coordination polymer
1600 cm typical for carboxylate groups.
Ó 2010 Elsevier B.V. All rights reserved.
1
. Introduction
chemistry of hybrid frameworks and multinuclear assemblies orig-
inate from applications of these new functional materials [9,10].
The carboxylic acid anions exhibit a variety modes of binding to
metal ions. Their complexes have been extensively studied due
to their ability to coordinate in monodentate mode [11,12], form
stable chelates [13,14], create di- and multinuclear species
[15,16] and polymeric compounds with different topologies and
dimensionality [17,18]. In addition, the carboxylate groups are
excellent hydrogen bond acceptors and are used to create supra-
molecular assemblies [19].
In accordance to above mentioned findings, the studies on the
coordination compounds of mefenamic acid with biologically impor-
tant s block elements were carried out. It was previously claimed that
sodium and calcium salts were obtained, characterised by IR spectro-
scopy and structurally studied [20,21], but these results are partially
questionable and partially seem to be wrong (for detailed discussion
see comment). Apart from mentioned s block elements, the mefene-
mates coordination compounds with p and d block elements werealso
studied and structurally characterised, namely bis(N-(2,3-dimethyl-
phenyl)aniline-2-carboxylato)-bis(2-pyridylmethanol)-copper(II) [22],
Mefenamic acid (2-(2,3-dimethylphenyl)aminobenzoic acid,
Hmef) belongs to the fenamates family and is commonly used as
non-steroidal anti-inflammatory, analgesic, and antipyretic agent
[
1,2]. It has been shown to affect various types of membrane chan-
nels [3,4]. The disadvantage of mefenamic acid is its low solubility
in aqueous media that influences the bioavailability and pharma-
cokinetic behaviour [5,6]. Moreover, it can cause the side effects
such as nausea, stomach upset, loss of appetite, headache, rash,
etc. The variable bioavailability of mefenamic acid is related to
pharmaceutical preparation process and in a consequence to vari-
ations in dissolution rate. It is known that the particle size distribu-
tion, crystal form, crystallinity and surface area of the drug are
important parameters that influence its dissolution [7]. Thus it
has been suggested that solubility is one of the main factors in
determining bioavailability and reducing side effects. The search
of mefenamic acid derivatives, possessing enlarged pharmacologi-
cal activity, lower toxicity and higher solubility is continuously an
active area of investigations. It has been shown that the stability
and solubility of mefenamic acid can be enhanced, for example,
by forming the inclusion complexes with cyclodextrins [8]. On
the other hand the development and studying of coordination
bis((
methyl-di-tin(IV)) [23], bis((
lamino)benzoato)-tetra-n-butyl-di-tin(IV))
-3-pyridylmethanol-N,O)-bis(2-(2,3-dimethylanilino)benzoato-
3
-oxo)-bis(
l
2
-2-(2,3-dimethylphenylamino)benzoato)-tetra-
-oxo)-bis( -2-(2,3-dimethylpheny-
[23], catena-(bis
l
3
l
2
(l
2
O)-cadmium(II))
[24],
diaqua-bis(2-((2,3-dimethylphenyl)
*
Corresponding author. Tel.: +48 42 6313137; fax: +48 42 6313103.
E-mail address: rafal.kruszynski@p.lodz.pl (R. Kruszynski).
0
0
amino)benzoato-O)-bis(N ,N -diethylnicotinamide-N)-copper(II) [25],
0
022-2860/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2010.02.045

8
0
R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
0
tetrakis(N-xylyl-anthraniloato-O,O )-bis(dimethylformamide-O)-di-
copper(II) [26,27], (2-[bis(2,3-dimethylphenyl)amino]benzoato)-
triphenyl-tin [28], bis(N-(2,3-dimethylphenyl)aniline-2-carboxyla-
to 0.299 g (4.26 mmol) of potassium methanolate (>99%, obtained
from POCh) dissolved in 25 cm of methanol. The solutions were
stirred and left at room temperature. After a week the crystals of
hydrated salts grew from the solutions with 74% and 69% yields,
3
to)-bis(methanol)-bis(pyridine)-copper(II) [22,29], tetrakis(
N-(2,3-dimethylphenyl)anthranilato-O,O )-bis(dimethylsulfoxide)-
-2-((2,3-dimethylphenyl)amino)ben-
zoato-O,O )-trimethyl-tin(IV)) [31].
l
2
-
0
respectively, for [Na(mef)(H
(2). 0.182 g (4.28 mmol) of calcium hydride (99.9%, obtained from
Aldrich) was added slowly to 15 cm of methanol and after reac-
2
O)
2
]
n
ꢀnH
2 2 n
O (1) and [K(mef)(H O)]
di-copper(II) [30], catena-((
l
2
0
3
tion completing 1.000 g (4.14 mmol) of mefenamic acid was added.
The mixture was stirred on the magnetic stirrer for 2 weeks, heated
to boiling and filtered after cooling. The precipitate was mixed
with methanol, the obtained suspension was boiled, cooled and fil-
tered. Combined filtrates were left at room temperature. After a
2
. Experimental
2.1. Synthesis
week the crystals of [Ca(mef)
solution with 51% yield. Elemental analysis (calculated/found): 1:
C 56.78/56.54, H 6.35/6.42, N 4.41/4.40, O 25.21/25.29, Na 7.2/
2
(H
2
O)
2
]
n
ꢀnH
2
O (3) salt grew from
1
.000 g (4.14 mmol) of mefenamic acid (Hmef, obtained from
Sigma) was added to 0.226 g (4.18 mmol) of sodium methanolate
>99%, obtained from POCh) dissolved in 12 cm3 of methanol and
(
Fig. 1. The comparison of recorded XRPD patterns (curves) and these ones calculated on the basis of single crystal measurements (bars) for compounds 1–3. Reflections of the
standard were subtracted from the recorded XRPD patterns.

R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
81
7
1
1
.4; 2: C 60.58/60.49, H 5.42/5.44, N 4.71/4.65, O 16.14/16.20, K
3.1/13.4; 3: C 62.70/62.63, H 5.96/6.00, N 4.87/4.71, O 19.49/
9.41, Ca 7.0/6.9. The comparison of recorded X-ray powder dif-
synthesis after four cycles of anisotropic refinement, and refined
as ‘‘riding” on the adjacent atom with individual isotropic displace-
ment factor equal 1.2 times the value of equivalent displacement
factor of the patent non-methyl carbon atoms and 1.5 times for
patent methyl carbon, nitrogen and oxygen atoms. The carbon
bonded hydrogen atom positions were idealised after each cycle
of refinement. The methyl groups were allowed to rotate about
their local threefold axis. At the end of compound 3 refinement,
fraction patterns and these ones calculated on the basis of single
crystal measurements are presented in Fig. 1.
The salts 1, 2, and 3, can be also obtained by direct acid–base
reaction in water or in methanol media (as it was previously re-
ported [20,21]), however, in all these cases the products were con-
taminated by metals hydroxides and carbonates as well as by
unreacted Hmef. In the case of compound 3 over 70% of total
amount of calcium occurs in form of inorganic salts. Nevertheless
of salt creation, in all cases addition of base to the acid solution
enlarges the Hmef solubility.
ꢁ
3
on the difference Fourier syntheses appears the 1.437 e Å peak
at 0.3059 0.5120 0.4390 (1.08 Å from Ca1 atom). The next peak is
ꢁ3
distinctly smaller (0.810 e Å ) and comparable with the deepest
ꢁ3
hole (ꢁ0.868 e Å ). This can suggest that absolute difference Fou-
rier syntheses maximum may originate from the strong anisotropy
of the electron density around calcium atom, as it was previously
found, for example, for rhenium coordination compounds [33].
The SHELXS97, SHELXL97 and SHELXTL [34] programs were used
for all the calculations. Atomic scattering factors were those incor-
porated in the computer programs. Selected interatomic bond dis-
tances and angles are listed in Table 2. The hydrogen bonds
geometry is gathered in Table 3.
2.2. Crystal structure determination
Colourless needle shape crystals of 1, 2 and 3 were mounted
in turn on a KM-4-CCD automatic diffractometer equipped with
CCD detector, and used for data collection. X-ray intensity data
were collected with graphite monochromated MoK
k = 0.71073 Å) at temperature 291.0(3) K, with scan mode. A
0 s exposure time was used for each crystal. The unit cells param-
a radiation
(
2
x
2.3. Other measurements
eters were determined from least-squares refinement of the set-
ting angles of 4992, 4012 and 6883 the strongest reflections,
respectively, for 1, 2 and 3. Details concerning crystal data and
refinement are given in Table 1. Examination of reflections on
two reference frames monitored after each 20 frames measured
showed 0.00%, 0.04% and 0.78% loss of the intensity, respectively,
for 1, 2 and 3. During the data reduction above decay correction
coefficients were taken into account. Lorentz, polarization, and
numerical absorption [32] corrections were applied. The structures
were solved by direct methods. All the non-hydrogen atoms were
refined anisotropically using full-matrix, least-squares technique
Elemental analyses were carried out using a Carbo-Erba C, H, N
analyzer. Sodium and potassium content was determined by flame
photometry and content of calcium was determined by complexo-
metric titration with EDTA as a complexing agent [35]. IR spectra of
complexes were recorded as KBr disc on a Bruker spectrometer
over the range 4000–400 cm . The thermal characteristics were
determined on PerkinElmer Differential Scanning Calorimeter
DSC4000. The X-ray powder diffraction (XRPD) patterns were mea-
sured in reflection mode on an XPert PRO X-ray powder diffraction
system equipped with a Bragg–Brentano PW 3050/65 high resolu-
tion goniometer and PW 3011/20 proportional point detector. The
ꢁ1
2
on F . All the hydrogen atoms were found from difference Fourier
Table 1
Crystal data and structure refinement details for 1, 2 and 3.
Compound
1
2
3
Empirical formula
C
15
H20NNaO
5
C
15
H16KNO
3
C
30 2 7
H34CaN O
Formula weight
317.31
297.39
574.67
Temperature [K]
291.0(3)
Wavelength [Å]
Crystal system, space group
k(MoK
a
) = 0.71073l
Triclinic, P1ꢀ
Unit cell dimensions [Å, °]
a = 6.5387(2)
b = 6.8051(3)
c = 19.2000(9)
a = 6.9567(2)
b = 7.0650(2)
c = 16.3165(5)
a = 7.7226(2)
b = 10.8220(3)
c = 18.4199(5)
a
= 81.615(4)
b = 89.757(3)
= 70.064(4)
a
= 95.210(2)
b = 94.715(2)
= 114.279(3)
a
= 97.231(2)
b = 91.459(2)
= 106.269(3)
c
c
c
Volume [Å3]
Z, Calculated density [Mg/m ]
Absorption coefficient [mm
F(0 0 0)
793.60(6)
2, 1.328
0.122
336
721.65(4)
2, 1.369
0.374
312
1463.04(7)
2, 1.304
0.263
608
3
ꢁ
1
]
Crystal size [mm]
h range for data collection [°]
Index ranges
0.117 ꢂ 0.013 ꢂ 0.010
2.15–25.05
ꢁ7 6 h 6 7, ꢁ8 6 k 6 7,
0.203 ꢂ 0.018 ꢂ 0.017
0.154 ꢂ 0.010 ꢂ 0.009
2.53–25.00
1.98–36.67
ꢁ6 6 h 6 8, ꢁ8 6 k 6 8,
ꢁ19 6 1 6 19
7396/2548
ꢁ12 6 h 6 11, ꢁ17 6 k 6 12,
ꢁ27 6 1 6 19
20342/10305
[R(int) = 0.0356]
98.3
ꢁ
22 6 1 6 22
7892/2800
(int) = 0.0336]
Reflections collected/unique
[R
[R(int) = 0.0196]
100.0
Completeness to 2h = 50° [%]
Refinement method
Min. and max. transmission
Data/restraints/parameters
Goodness-of-fit on F2
100.0
Full-matrix least-squares on F2
0.990 and 0.999
2548/0/183
0.996 and 1.000
2800/0/201
1.091
0.994 and 1.000
10305/0/365
1.015
1.078
Final R indices [I > 2
r
(I)]
R
1
= 0.0399,
wR = 0.1118
= 0.0471,
wR = 0.1149
0.192 and ꢁ0.309
R
1
= 0.0309,
wR = 0.0867
= 0.0393,
wR = 0.0894
0.196 and ꢁ0.219
R
1
= 0.0285,
wR = 0.0638
= 0.0570,
wR = 0.1036
1.437 and ꢁ0.868
2
2
2
R indices (all data)
R
1
R
1
R
1
2
2
2
Largest diff. peak and hole [e Åꢁ3]

8
2
R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
Table 2
Table 2 (continued)
Selected structural data for 1, 2 and 3 [Å, °]. Cg means aromatic C1–C6 ring centroid.
O21ACa1AO41
O1ACa1AO41
95.6(3)
81.4(3)
155.6(3)
138.9(3)
127.3(3)
80.7(3)
88.3(3)
70.2(4)
162.0(4)
104.0(4)
92.0(4)
68.8(3)
168.5(3)
76.4(3)
79.0(3)
77.2(3)
50.9(3)
118.5(3)
167.2(9)
88.8(8)
120.1(13)
100.2(8)
Compound 1
Na1AO3#1
Na1AO3
Na1AO4
Na1AO1
Na1AO4#2
C7AO2
2.3467(13)
2.3924(11)
2.4306(12)
2.4477(11)
2.5080(12)
1.2444(16)
1.2643(16)
3.5704(11)
3.7899(11)
O22#2ACa1AO41
O21ACa1AO2#5
O1ACa1AO2#5
O22#2ACa1AO2#5
O41ACa1AO2#5
O21ACa1AO42
O1ACa1AO42
O22#2ACa1AO42
O41ACa1AO42
O2#5ACa1AO42
O21ACa1AO1#5
O1ACa1AO1#5
O22#2ACa1AO1#5
O41ACa1AO1#5
O2#5ACa1AO1#5
O42ACa1AO1#5
C7AO1ACa1
C7AO1
Na1ꢀ ꢀ ꢀNa1#1
Na1ꢀ ꢀ ꢀNa1#2
O3#1AANa1AO3
O3#1ANa1AO4
O3ANa1AO4
O3#1ANa1AO1
O3ANa1AO1
82.23(4)
103.14(4)
101.09(4)
107.50(4)
88.81(4)
148.81(4)
101.78(4)
175.64(5)
79.77(4)
O4ANa1AO1
O3#1ANa1AO4#2
O3ANa1AO4#2
O4ANa1AO4#2
O1ANa1AO4#2
O2AC7AO1
C7AO1ACa1#5
O1AC7AO2
C7AO2ACa1#5
88.34(4)
122.80(12)
123.75(8)
C7AO1ANa1
Symmetry transformations used to generate equivalent atoms: #1 ꢁ x + 2, ꢁy,
ꢁz + 1; #2 ꢁ x + 2, ꢁy + 1, ꢁz + 1; #3 ꢁ x + 3, ꢁy + 1, ꢁz + 1; #4x + 1, y, z; #5 ꢁ x + 1,
ꢁy + 1, ꢁz + 1.
Compound 2
K1AO1
K1AO3#3
K1AO3
K1AO1#2
K1AO2
K1AC1#4
K1AC2#4
K1AC3#4
K1AC4#4
K1AC5#4
K1AC6#4
K1ACg#4
K1ꢀ ꢀ ꢀK1#2
K1ꢀ ꢀ ꢀK1#3
C7AO1
2.6982(10)
2.7689(11)
2.7982(12)
2.8702(14)
2.8842(11)
3.3927(14)
3.4962(15)
3.552(2)
3.4322(19)
3.309(2)
3.2881(17)
3.112(2)
Table 3
Hydrogen-bonds for 1, 2 and 3 [Å, °].
DAHꢀ ꢀ ꢀA
Compound 1
O3AH3Oꢀ ꢀ ꢀO2
d(D–H)
d(Hꢀ ꢀ ꢀA)
d(Dꢀ ꢀ ꢀA)
<(DHA)
0.89
0.88
0.96
0.91
0.92
0.85
0.93
0.93
0.93
0.96
1.78
1.91
1.83
2.01
1.88
1.91
2.27
2.51
2.45
2.45
2.6610(14)
2.7831(15)
2.7584(16)
2.9231(16)
2.5883(16)
2.7315(14)
3.158(2)
3.1267(17)
2.7743(18)
2.856(3)
168.5
169.9
161.9
177.8
131.5
161.2
159.2
124.3
100.5
105.4
O3AAH3Pꢀ ꢀ ꢀO99#1
O4AH4Oꢀ ꢀ ꢀO99#2
O4AH4Pꢀ ꢀ ꢀO1#2
N1AH1 Nꢀ ꢀ ꢀO2
3.8570(9)
4.2189(9)
1.2550(18)
1.2441(17)
O99AH99Oꢀ ꢀ ꢀO1#3
O99AH99Pꢀ ꢀ ꢀN1#4
O99AH99Pꢀ ꢀ ꢀO2#4
C6AH6ꢀ ꢀ ꢀO1
C7AO2
O1AK1AO3#3
O1AK1AO3
158.78(4)
113.72(3)
81.46(4)
92.38(3)
71.34(3)
92.86(4)
46.04(3)
118.48(3)
159.67(4)
90.31(4)
85.58(4)
92.36(4)
103.15(4)
163.67(4)
96.80(4)
99.15(8)
96.04(9)
122.35(13)
90.53(8)
C14AH14Aꢀ ꢀ ꢀN1
O3#3AK1AO3
O1AK1AO1#2
O3#3AK1AO1#2
O3AK1AO1#2
O1AK1AO2
Compound 2
O3AH3Oꢀ ꢀ ꢀO2#5
O3AH3Pꢀ ꢀ ꢀN1#2
N1AH1 Nꢀ ꢀ ꢀO1
C14AH14Cꢀ ꢀ ꢀN1
0.87
0.90
0.88
0.96
1.88
2.21
1.87
2.46
2.7397(17)
3.083(2)
2.6090(15)
2.865(3)
172.0
163.3
140.3
105.0
O3#3AK1AO2
O3AK1AO2
Compound 3
O41AH41Oꢀ ꢀ ꢀO22#6
O41AH41Pꢀ ꢀ ꢀO99#6
O42AH42Oꢀ ꢀ ꢀO99
O42AH42Pꢀ ꢀ ꢀO2#3
N1AH1 Nꢀ ꢀ ꢀO2
0.82
0.89
0.92
0.88
0.86
0.86
0.72
0.78
0.93
0.93
0.96
0.96
2.22
2.38
2.06
2.19
1.95
2.09
2.48
2.04
2.43
2.46
2.40
2.48
3.038(12)
3.15(2)
179.5
143.4
133.6
123.9
133.8
127.5
154.2
158.9
100.4
147.5
106.2
107.8
O1#2AK1AO2
O3AK1ACg#4
O3#3AK1ACg#4
O1AK1ACg#4
O1#2AK1ACg#4
O2AK1ACg#4
C7AO1AK1
C7AO1AK1#2
O2AC7AO1
C7AO2AK1
2.779(19)
2.780(13)
2.617(14)
2.702(14)
3.15(2)
2.779(19)
2.757(15)
3.279(16)
2.825(17)
2.920(19)
N21AH21 Nꢀ ꢀ ꢀO22
O99AH99Oꢀ ꢀ ꢀO41#2
O99AH99Pꢀ ꢀ ꢀO42
C6AH6ꢀ ꢀ ꢀO1
C6AH6ꢀ ꢀ ꢀO21
C14AH14Bꢀ ꢀ ꢀN1
C34AH34Aꢀ ꢀ ꢀN21
Compound 3
Ca1AO21
Ca1AO1
Ca1AO22#2
Ca1AO41
Ca1AO42
Ca1AO2#5
Ca1AO1#5
Ca1ꢀ ꢀ ꢀCa1#5
Ca1ꢀ ꢀ ꢀCa1#2
O1AC7
C7AO2
O21AC27
C27AO22
O21ACa1AO1
O21ACa1AO22#2
O1ACa1AO22#2
2.250(9)
2.339(9)
2.351(8)
2.393(8)
2.508(10)
2.412(9)
2.670(9)
3.940(5)
4.838(5)
1.251(15)
1.282(15)
1.250(14)
1.255(13)
93.7(3)
Symmetry transformations used to generate equivalent atoms: #1 ꢁ x + 2, ꢁy,
z + 1; #2x + 1, y, z; #3 ꢁ x + 1, ꢁy + 1, ꢁz + 1; #4 ꢁ x + 1, ꢁy, ꢁz + 1; #5x + 1, y + 1,
z; #6x ꢁ 1, y, z.
ꢁ
1
CuKa radiation was used. The patterns were measured at 291.0(2)
K in the range 2–90° with the narrowest beam attenuator. A dia-
mond powder was used as an internal reference. The samples were
sprinkled onto the sample holders using a small sieve, to avoid a
preferred orientation. The thicknesses of the samples were no
more than 0.1 mm. During the measurements each specimen was
spun in the specimen plane to improve particle statistics.
1
H
1
3
107.0(3)
88.0(3)
NMR (250 MHz) and C NMR spectra were recorded with Bruker
DPX-250 spectrometer with TMS as an internal standard. Signal

R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
83
Table 4
1
H NMR data. Atom numbering scheme is as in the structural drawings. The chemical shifts (d) are given in [ppm] and coupling constants (J) are given in [Hz].
Compound
H6
H5
H4
H3
H11
H12
H13
H
H
3
(C14)/
(C15)
3
Mefenamic acid [23]a 8.03 d
6.69 dd
7.28 t
6.69 dd
7.10 m
7.10 m
7.10 m
2.18 s/2.34 s
2.13 s/2.06 s
1
2
7.89 dd
6.60 m
7.03 m
6.59 d
6.73 d
6.94 t
7.08 d
3
3
3
3JH5–H6 = 8.3
3
3
3
= 3
= 3
= 3
3
J
H3–H4 = 7.8
J
H3–H4 = 7.8
J
H4–H5
ꢃ
J
H5–H6 = 8.3
J
H4
0
–H5
0
0
= 7.5
= 7.6
J
H4
0
–H5
0
0
0
J
H5
J
H5
J
H5
0
0
0
–H6
–H6
–H6
0
0
0
= 7.5
= 7.6
= 7.1
J
H5
0
–H6
0
0
= 7.5
= 7.6
4JH3–H5 = 1.7 3JH4–H5 = 8.3
7.93 dd 6.62 m
4JH3–H5 = 1.7
7.09 m
6.78 d
6.85 d
6.99 t
7.11 d
2.27 s/2.18 s
2.30 s/2.14 s
3
3
3
3JH5–H6 = 8.3
3
3
3
3
J
H3–H4 = 7.8
4JH3–H5 = 1.7 3JH4–H5 = 8.3
.94 dd 6.62 m
J
H3–H4 = 7.8
J
H4–H5
ꢃ
J
H5–H6 = 8.3
J
H4
0
–H5
J
H4
0
–H5
J
H5 –H6
0
4JH5–H3 = 1.7
7
7.18 m
6.66 d
6.97 dd
7.05t
7.09 dd
3
3
3JH3–H4 = 7.9
3
3
3
3
3
3
J
H3–H4 = 7.9
J
H4–H5
ꢃ
J
J
H4–H5 = 7.9
H5–H6 = 8.4
J
H5–H6 = 8.4
J
J
H4
0
–H5
0
= 7.1
= 2.3
J
H4
0
–H5
J
J
H5
0
–H6
0
= 7.1
= 2.3
4JH3–H5 = 1.7 4JH4–H6 = 1.1
3
4
4
0
0
0
0
H4
–H6
H4
–H6
4JH3–H5 = 1.7
a
3
spectrum was recorded in CDCl , coupling constants were not given.
assignments were accomplished via analysis of HMBC, HMQC and
COSY experiments. The chemical shifts (d) [ppm] and coupling con-
stants (J) [Hz] were collected in Tables 4 and 5. All NMR spectra
and next they melt in complexed water. The recrystallisation of
anhydrous compounds begins at 120 °C due to evaporation of
water. The anhydrous salts melt with decomposition at 282–291
and 296–299 °C, respectively, for 1 and 2. The compound 3 loses
its internal water within temperature range 66–106 °C without
melting and anhydrous salt melt with decomposition at 180–
were recorded in CD
.4. Theoretical calculations
Geometry optimisation and vibrational analysis were per-
3
OD.
2
1
88 °C. The elemental analyses of anhydrous compounds resemble
well to the theoretical percentage amounts of the elements in
M(mef) (where M = Na, K) and Ca(mef) (calculated/found: 1: C
8.43/68.37, H 5.36/5.44, N 5.32/5.5.28, O 12.15/12.11, Na 8.7/
2
formed using the B3LYP functional [36,37] in conjunction with
the 6-31++G(d,p) basis set, and GAUSSIAN03 [38] program package
was used. Vibrational frequencies were calculated on the basis of
energy second derivatives referenced to the mass-weighted coordi-
nates obtained from transferring Cartesian nuclear coordinates.
The geometric parameters of Hmef were employed from crystal
structure data [39]. The optimised geometrical parameters were
in good agreement with those found from X-ray measurement. A
correction factor of 0.9613 [40] was applied to all frequencies.
6
8
1
1
.9; 2: C 64.49/64.52, H 5.05/5.15, N 5.01/4.96, O 11.45/11.52, K
4.0/14.3; 3: C 69.21/69.16, H 5.42/5.49, N 5.38/5.43, O 12.29/
2.35, Ca 7.7/7.6). The XRPD patterns of anhydrous compounds
were different from these of Hmef what proofs that organic salts
do not decompose to organic acid and inorganic salts. Heating
the samples 1–3 at 120 °C until the weight is constant (about
4
h) shows 17.039%, 6.061%, 9.411% loss of mass what corresponds
well to the amount of water in 1, 2 and 3, respectively, (theoreti-
cally 17.032%, 6.058%, 9.404%, respectively).
3
. Results and discussion
A perspective view of 1, 2 and 3 monomers structures, together
with the atom numbering scheme, is shown in Figs. 2–4. All atoms
in studied compounds lie in general positions, but location of two
inversion centres near central atoms of monomers expands com-
The complexes are air stable and soluble in water. The com-
plexes 1 and 2 are stable up to 59.3 and 77.4 °C, respectively,
Table 5
1
3C NMR data. Atom numbering scheme is as in the structural drawings.
Compound
C7
C2
C1
C6
C5
C4
C3
C8
C9
C10
C11
C12
C13
C14/C15
Mefenamic acid [23]a
1
2
3
173.0
176.0
177.3
150.0
150.3
147.9
149.2
140.6
109.2
120.7
122.2
115.5
132.4
132.0
133.4
133.2
116.1
116.3
117.7
117.0
135.2
131.2
132.5
123.6
113.7
113.6
115.0
114.4
138.4
130.5
131.9
133.0
132.9
137.8
139.2
125.3
138.8
140.8
142.2
139.2
123.7
125.1
126.4
127.3
126.0
125.7
127.1
134.1
127.2
120.6
121.9
127.0
20.7/14.3
19.9/13.2
21.3/14.6
20.6/14.1
Fig. 2. The molecular conformation of compound 1 with atom numbering, plotted with 50% probability of displacement ellipsoids. The symmetry generated atoms and bonds
are indicated by dashed lines (primed atoms are obtained by ꢁx + 2, ꢁy, ꢁz + 1 symmetry transformation and double-primed by ꢁx + 2, ꢁy + 1, ꢁz + 1 one).

8
4
R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
Fig. 4. The molecular conformation of compound 3 with atom numbering, plotted
with 50% probability of displacement ellipsoids. The symmetry generated atoms
Fig. 3. The molecular conformation of compound 2 with atom numbering, plotted
with 50% probability of displacement ellipsoids. The symmetry generated atoms
and bonds are indicated by dashed lines (primed atoms are obtained by ꢁx + 2,
and bonds are indicated by dashed lines (primed atoms are obtained by ꢁx + 1,
ꢁ
y + 1, ꢁz + 1 symmetry transformation and double-primed by ꢁx + 2, ꢁy + 1,
z + 1 one).
ꢁ
ꢁ
y + 1, ꢁz + 1 symmetry transformation, double-primed by ꢁx + 3, ꢁy + 1, ꢁz + 1,
triple-primed by x + 1, y, z, quadruple x ꢁ 1, y, z and starred by ꢁx + 3, ꢁy + 1, ꢁz + 1
one).
1
is composed from four bridging bidentate water molecules (three
equatorial and one axial) and one monodentate carboxylate group
axial one) of mefenamate ion. In compound 2, the potassium atom
is coordinated by electrons of aromatic ring (axial position), two
bridging bidentate water molecules (equatorial ones) and three
oxygen atoms from two tridentate chelating–bridging carboxylate
groups (one group provides two oxygen atoms coordinating in che-
lating mode and occupying equatorial positions in polyhedron, and
second one coordinates via bridging oxygen atom in axial position;
this last atom participates in chelating of next metal atom in the
polymer chain). The K1AC(aromatic ring) distances (Table 2) lie in
plex molecules to the one-dimensional polymers along crystallo-
graphic b axis (compound 1, Fig. 5) and a axis (compounds 2 and
(
p
3, Figs. 6 and 7). The outer coordination sphere water molecule
in compound 3 shows symptoms of disorder what manifests in rel-
atively large values of orthogonalised atomic displacement param-
eters (oADPs). The central atoms are five, six (the aromatic ring is
considered as one point node coordinating via ring centroid) and
seven coordinated, respectively, for sodium, potassium and cal-
cium complexes and coordination polyhedra adopt, respectively,
slightly distorted trigonal, tetragonal and pentagonal bipyramid
range of a conservative limit for Kꢀ ꢀ ꢀ
p interactions [44,45], thus
it can be supposed that these interactions are significant in con-
(Fig. 8) [41–43]. The coordination sphere around central atom of
Fig. 5. The polymer chain of 1. The not involved into the polymer chain outer coordination sphere water molecule and mefenamate ion are omitted for clarity.

R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
85
Fig. 6. The polymer chain of 2. The not involved into the polymer chain 1-amine-2,3-dimethylphenyl atoms of mefenamate ion are omitted for clarity.
Fig. 7. The polymer chain of 3. The not involved into polymer water molecules and 2-(2,3-dimethylphenyl)aminophenyl atoms of mefenamate ion are omitted for clarity.
struction of coordination sphere and in consequence in the crea-
tion of polymer chain. Noteworthy is the fact that each mefena-
mate ion coordinates three potassium cations, one via chelating
can be found in some s block coordination polymers, e.g. in cate-
0
na-(bis(
l
2
-N-Phenylanthranilato-O,O,O )-bis(methanol)-calcium)
[46], but the structure of polymer chains is different than in 2 or 3.
The planar within the experimental error aromatic rings are in-
clined at 64.11(5)°, 62.66(6)°, 48.4(4)° and 69.1(4)°, respectively,
for compounds 1, 2, 3 (rings containing C1 and C8 atoms) and 3
(rings containing C21 and C28 atoms). The aromatic rings of benzo-
ate moiety are inclined at 1.9(2)°, 12.8(2)°, 14.6(9)° and 20(1)° to
carboxylate groups, for compounds, respectively, as above. All che-
lating carboxylate groups are asymmetrically bonded to the metal
cations (Table 2). Noteworthy is the fact that one of carboxylate
groups of 3 shows rare (close to linear) coordination mode to the
metal, and observed C7AO1ACa1 angle of 167.2(9)° lies far beyond
preferred values of 93°, 119° and 127° [47] (Fig. 9). The polymer
carboxylate group, one by bridging oxygen atom and one via
p
electrons of aromatic ring. The central atom of compound 3 is coor-
dinated by two monodentate water molecules (one axial and one
equatorial) and five oxygen atoms from four carboxylate groups
(
two tridentate chelating–bridging and two bidentate bridging)
of mefenamate ions. The one atom of bidentate bridging carboxyl-
ate group exists in axial position and all other carboxylate groups
oxygen atoms occupy equatorial positions. In 3 (as in 2) the triden-
tate chelating–bridging carboxylate group acts as bidentate chelat-
ing group toward one central atom and as monodentate group
toward next metal atom in the polymer chain. Such coordination

8
6
R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
a
b
c
Fig. 8. The central atom coordination polyhedra. (a) for compound 1 (symmetry transformations as in Fig. 1), (b) for compound 2 (symmetry transformations as in Fig. 2, Cg
0
00
000
means aromatic C1 –C6 ring centroid.) and (c) for compound 3 (symmetry transformations as in Fig. 3).
chains of compounds 1 and 2 are assembled via intermolecular
OAHꢀ ꢀ ꢀO medium strength hydrogen bonds (Table 3) to the two-
dimensional net extending along crystallographic (0 0 1) and
Topacli and Ide [20] previously claimed that sodium and cal-
cium salts were obtained, however, structural and diffraction re-
sults are in a disagreement with both now presented and
previously reported data [39,50]. For example, Topacli and Ide
found most intense diffraction peaks at 2h equal to 38.2° and
38.4° [20], respectively, for Na and Ca salts, whereas these peaks
in salts 1 and 3 exist at 4.65° and 4.87°. Additionally, Topacli and
Ide observed strong diffraction peaks at 2h about 38° and 45° in
the salts and in the free acid, what is in a disagreement with both,
currently presented and known data [39,51], because there is no
significant diffraction beyond 2h diffraction angle equal to 35° (in
the free acid and in the respect salts). This strongly suggests that,
even if Topacli and Ide obtained reported salts, these organic salts
were largely contaminated by highly symmetrical (in crystalline
(
0 1 0) planes, respectively, for 1 and 2. Additionally, in the both
structures can be found intramolecular medium strength NAHꢀ ꢀ ꢀO,
OAHꢀ ꢀ ꢀO and weak CAHꢀ ꢀ ꢀO hydrogen bonds (Table 3) [48,49] pro-
viding additional stabilisation to the structure. In the case of com-
pound 3 the intermolecular hydrogen bonds do not lead to extend
the structure to the second dimension because they link water
molecules to the single polymer chain via two dihydrogen
OAHꢀ ꢀ ꢀO bonds. As it is in 1 and 2, in 3 the medium strength
NAHꢀ ꢀ ꢀO, OAHꢀ ꢀ ꢀO and weak CAHꢀ ꢀ ꢀO hydrogen bonds interlink
the polymer chain. The face-to-face stacking interactions are not
observed in the presented structures.

R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
87
phase) inorganic salts. Inorganic salts give relatively simple IR
spectra (in comparison to organic compounds) thus above-men-
tioned impurity of complex salts does not influence the key fea-
tures of the previously reported [20,21] IR spectra analyses.
that the polymeric structure is not retained in CD
ical differences exist in environment of carboxylic group due to its
deprotonation in the salts. In the case of compound 3 some essen-
tial upfield and downfield shifts are observed in C NMR spectra
(Table 5). Because in the single mef ion none of the aromatic rings
can be placed over other ring, the interaction of ring currents should
lead to deshielding of atoms of both rings. In the presented case
only one ring is deshielded, and the second one is shielded, what
suggests that a part of polymeric structure is maintained in solution
and rings (containing C8-C13 atoms) of mef ion from one mer are
3
OD solution. Typ-
1
3
Topacli and Ide also assume that Hmef reacts with Ca(OH)
2
in ratio
1
:1 with creation of hydride HCa(mef) which is rather senseless
because even if 1:1 ratio will be retained in salt, the Ca(OH)(mef)
will be created instead of mentioned hydride.
1
13
The H and C NMR shifts of 1 and 2 recorded in CD
3
OD are very
similar to these ones of the free acid (Tables 4 and 5), what suggests
Fig. 9. Histogram showing preferred MAOAC angles in metal-carboxylate systems (according to Cambridge Structural Database [47]).
Fig. 10. The homosynthon motif observed in the crystal structure of Hmef.

8
8
R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
Table 6
Vibrational frequencies and assignment of Hmef and its dimer.
Table 7
Vibrational frequencies and assignment of Hmef coordination polymer compounds.
Hmef monomer
Hmef dimer
1
2
3
m
exp.
m
theor.
m
theor.
Assignment
m
exp.
m
exp.
m
exp.
Assignment
3
624
3351
053–3104
3430
3345
3053–3096
m
m
m
m
m
m
m
m
m
m
(OH)
(NH)
3085–3500 3000–3600 3000–3620
2743–3085 2850–2971 2830–2956
m
m
m
m
m
m
m
m
m
s
(CH)aryl
as(CH ),
as(COO ), d(NH)
(CC)aryl, d(NH)
(CC)aryl, d(NH)
,
m
mas(CH)aryl, m(OH), m(NH)
3
2
ꢁ
300 m
3
s
(CH
3
)
ꢁ
3
s
(CH)aryl
(CH)aryl
,
,
m
m
as(CH)aryl
as(CH)aryl, m(OH)
1600
1571
1535
1485
1465
1364
1278
1157
1057
1043
835
1603
1571
1557
1486
1443
1367
1274
1150
1057
1028
844
1609
1578
1545
1493
1454
1385
1280
1156
1068
1043
858
760ꢁ
s
3250 b
2910–3013
1667
1591
2911–3010
1634
1590
1564
1500
1452
1430
1337
1302
1284
1148
1134
1116
1059
1038
943
3 s 3
as(CH ), m (CH )
(C@O), d(NH)
(CC)aryl
1
1
650 s
590 w, 1580 s
(CC)aryl, d(NH), d(CH)aryl
(CC)aryl, d(CH
3
), d(CH)aryl
ꢁ
1560
(CC)aryl, d(NH)
(CC)aryl, d(NH), d(CH)aryl
(CC)aryl, d(CH ), d(CH)aryl
), d(CH)aryl
(CC)aryl (C–COO), d(OH)
d(NH), d(CH)aryl
(CN), d(OH), d(CH)aryl
s
(COO )
1510 s
1460 w
1445 s
1325 m
1499
1457
1430
1342
(CN), d(OH), d(CH)aryl
3
d(OH), d(CH)aryl
d(CH
m
3
d(CH
d(CH
d(CH
d(CH)aryl
d(CH)aryl
d(OH), d(NH)
d(NH)
d(OH), d(NH)
d(OH)
m(MO)
3
), d(CH)aryl
3
), d(CH)aryl
3
)
, m
1305
1
1
235 s
165 m
1286
1153
m
778
769
812
d(OH), d(CH)aryl
d(OH), d(CH)aryl
d(OH), d(CH)aryl
d(CH
d(CH
d(CH
d(CH)aryl
d(CH)aryl
d(NH)
d(OH), d(NH)
d(OH)
750
750
760
1140
700
700
705
1
1
095 w
040 w
1118
1051
665
667
670
3
), d(CH)aryl
3
), d(CH)aryl
3
)
631
1036
526
409
890 m
780 m
750 m
660 w
937
746
732
630
467
425
746
735
634
611
1
and 2, the carboxylate groups have the same coordination func-
615
tion in the particular compounds. Taking into account the presence
of hydrogen bonds formed by the carboxylate groups it can be sta-
ted that these groups act in pentadentate fashion. The two differ-
ent coordination functions of carboxylate groups – tridentate
chelating–bridging and bidentate chelating – are confirmed for 3,
since in the spectrum of this compound the bands of the carboxyl-
ate stretching vibrations have more complex structure. Such a dis-
5
40 w
552
550
placed over second mer rings (containing C1AC6 atoms) similarly
as it was found in the crystal structure of 3.
The vibrational analysis was carried out for mefenamic acid and
its three coordination polymer compounds in the solid state. The
quantum mechanical calculations were performed for isolated
mefenamic acid molecule to examine the proposed vibrational
assignments and for dimer structure (Fig. 10) to check the position
of absorption bands assigned to the vibrations of hydrogen bonded
groups. All calculated frequencies are for gas-phase molecules. The
characteristic frequencies are listed in Tables 6 and 7.
ꢁ1
appearance of the band (at 1650 cm ) corresponding to C@O
stretching vibrations of COOH group and an appearance of two
bands corresponding to carboxylate ion stretching vibrations have
been previously observed for Na and Ca salts of mefenamic acid
[
20,21]. The NH group of mefenamate ion is involved in the intra-
molecular NAHꢀ ꢀ ꢀO hydrogen bonds in both Hmef and its three
coordination polymer compounds, but the band corresponding to
The theoretical and experimental vibrational frequencies of
Hmef are close. The frequency differences are observed for the
bending vibrations involving mainly the CH bonds. The experimen-
tal spectrum of monomer reveals characteristic NH stretching
NH bending vibrations is red-shifted for 1–3. The bands at 467,
ꢁ1
4
25 and 410 cm
are attributed to the m(NaAO), m(KAO) and
m(CaAO), respectively.
ꢁ1
vibrations at 3300 cm . The broad split absorption band in the fre-
ꢁ1
4. Supplementary data
quency range 2760–3250 cm is attributed to the
m(OH), m(CH)
vibrations of methyl and aryl groups. The single band at
ꢁ1
Tables of crystal data and structure refinement, anisotropic dis-
placement coefficients, atomic coordinates and equivalent isotro-
pic displacement parameters for non-hydrogen atoms, H-atom
coordinates and isotropic displacement parameters, bond lengths
and interbond angles have been deposited with the Cambridge
Crystallographic Data Centre under No CCDC740723, CCDC740724,
and CCDC740725, respectively, for compounds 1, 2 and 3.
1
650 cm is attributed to the overlapped C@O stretching vibra-
tions and NH bending vibrations. The bands around 1580, 1510
ꢁ1
and 1445 cm confirm the presence of aromatic CC bonds. The
ꢁ
1
OH bending vibration appears as a band at 1325 cm . The CN
ꢁ1
stretching mode is observed at 1255 cm . The medium intensity
ꢁ1
bands at 750 and 780 cm correspond to vibrations of aryl CH
bonds.
The most significant differences between experimental and cal-
culated vibrational frequencies of Hmef were observed for OH and
C@O stretching vibrations. They are caused by the presence of non-
covalent interactions in the solid state. The calculated frequencies
display remarkable bathochromic shift for dimer structure where
OH and C@O bonds are involved in hydrogen bonding, similarly
to the behaviour of hydrogen-bonded carboxylic group dimers
Acknowledgments
This work was financed by funds allocated by the Ministry of
Science and Higher Education to the Institute of General and Eco-
logical Chemistry, Technical University of Lodz. The GAUSSIAN03
calculations were carried out in the Academic Computer Centre
CYFRONET of the AGH University of Science and Technology in Cra-
cow, Poland (Grant No.: MNiSW/SGI3700/PŁódzka/040/2008).
[
52]. Differences between the solid state and gas phase results
indicate that the periodicity has a marked influence on the spectral
characteristics of the Hmef molecule.
The IR spectra of 1–3 showed the additional strong bands at ca.
References
ꢁ1
1
365 and 1600 cm , which can be assigned to the stretching
ꢁ
ꢁ
[1] D. Alves, I. Duarte, Eur. J. Pharmacol. 444 (2002) 47.
vibrations of carboxylate groups, the
s
m (COO ) and mas(COO ),
[
2] J.B. Rich, D.X. Rasmusson, M.F. Folstein, K.A. Carson, C. Kawas, J. Brandt,
Neurology 45 (1995) 51.
respectively. Since these bands are not split in the IR spectrum of

R. Kruszynski et al. / Journal of Molecular Structure 970 (2010) 79–89
89
[
3] M. Zhang, W.-J. Shi, X.-W. Fei, Y.-R. Liu, X.-M. Zeng, Y.-A. Mei, Toxicol. Appl.
Pharmacol. 226 (2008) 225.
[33] J.O. Dzi e˛ gielewski, S. Michalik, M. Jaworska, R. Kruszynski, J. Kusz, Pol. J. Chem.
79 (2005) 1193.
[
[
4] N. Teramoto, A.F. Brading, Y. Ito, Br. J. Pharmacol. 140 (2003) 1341.
5] D. Shinkuma, T. Hamaguchi, Y. Yamanaka, N. Mizuno, Int. J. Pharm. 21 (1984)
[34] G.M. Sheldrick, Acta Crystallogr. A64 (2008) 112–122.
[35] F.J. Welcher, The Analytical Uses of Etylenediamineteraacetic Acid, WNT,
Warsaw, Poland, 1963.
1
87.
[
[
[
6] S. Romero, B. Escalera, P. Bustamante, Int. J. Pharm. 178 (1999) 193.
7] A. Adam, L. Schrimpl, P.C. Schmidt, Drug Dev. Ind. Pharm. 26 (2000) 477.
8] T. Hłado n´ , J. Pawlaczyk, B. Szafran, J. Incl. Phenom. Macro. Chem. 35 (1999)
[36] A.D. Becke, J. Chem. Phys. 98 (1993) 5648.
[37] C. Lee, W. Yang, R.G. Parr, Phys. Rev. B37 (1988) 785.
[38] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A.
Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox,
H.P. Hratchian, J.B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann,
O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K.
Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S.
Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K.
Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J.
Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L.
Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M.
Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A.
Pople, Gaussian 03, Revision E.01, Gaussian, Inc., Pittsburgh PA, 2004.
[39] J.F. McConnell, F.Z. Company, Cryst. Struct. Commun. 5 (1976) 861.
[40] M.W. Wong, Chem. Phys. Lett. 256 (1996) 391.
4
97.
[
9] S. Wang, D.B. Mitzi, C.A. Field, A. Guloy, J. Am. Chem. Soc. 117 (1995) 5297.
[
[
10] P.J. Hagrman, D. Hagrman, J. Zubieta, Angew. Chem. Int. Ed. 38 (1999) 2638.
11] J. Moncol, M. Mudra, P. Lonnecke, M. Koman, M. Melnik, J. Coord. Chem. 57
(
2004) 1065.
[
[
12] J.R. Su, D.J. Xu, J. Coord. Chem. 58 (2005) 629.
13] A.D. Burrows, R.W. Harrington, M.F. Mahon, S.J. Teat, Cryst. Growth Des. 4
(
2004) 813.
[
[
[
14] A. Morsali, X.M. Chen, J. Coord. Chem. 57 (2004) 1233.
15] W.J. Evans, J.C. Brady, J.W. Ziller, J. Am. Chem. Soc. 123 (2001) 7711.
16] C. Ma, W. Wang, X. Zhang, C. Chen, Q. Liu, H. Zhu, D. Liao, L. Li, Eur. J. Inorg.
Chem. (2004) 3522.
17] Y. Zheng, J. Lin, Z. Kong, Polyhedron 19 (2003) 2111.
18] F. Bentiss, P. Roussel, M. Drache, P. Conflant, M. Lagrenee, J.P. Wignacourt, J.
Mol. Struct. 707 (2004) 63.
[
[
[
19] R. Kruszynski, A. Adamczyk, J. Radwanska-Doczekalska, T.J. Bartczak, J. Coord.
Chem. 55 (2002) 1209.
[41] M.C. Favs, D.L. Kepert, Aspects of the stereochemistry of four-coordination and
five-coordination, in: S.J. Lippard (Ed.), Progress in Inorganic Chemistry, vol.
27, John Willey & Sons, New York, 1980.
[42] D.L. Kepert, Aspects of the stereochemiastry of six-coordination, in: S.J.
Lippard (Ed.), Progress in Inorganic Chemistry, vol. 23, John Willey & Sons,
New York, 1977.
[43] D.L. Kepert, Aspects of the stereochemiastry of seven-coordination, in: S.J.
Lippard (Ed.), Progress in Inorganic Chemistry, vol. 25, John Willey & Sons,
New York, 1979.
[44] D.L. Clark, J.C. Gordon, J.C. Huffmann, R.L. Vincent-Hollis, J.G. Watkin, B.D.
Zwick, Inorg. Chem. 33 (1994) 5903.
[
[
[
20] A. Topacli, S. Ide, J. Pharm. Biomedi. Anal. 21 (1999) 975.
21] A. Bani-Jaber, I. Hamdan, B. Al-Khalidi, Chem. Pharm. Bull. 55 (2007) 1136.
22] M. Koman, M. Melnik, J. Moncol, S. Lorinc, T. Glowiak, Monograph Series of the
International Conferences on Coordination Chemistry (2003) 121.
23] V. Dokorou, Z. Ciunik, U. Russo, D. Kovala-Demertzi, J. Organomet. Chem. 630
[
[
[
[
[
[
[
[
[
[
(
2001) 205.
24] J. Moncol, D. Miklos, P. Segla, M. Koman, T. Lis, Acta Crystallogr. E64 (2008)
m440.
25] M. Melnik, M. Koman, L. Macaskova, T. Glowiak, J. Coord. Chem. 44 (1998)
1
63.
[45] N. Meyer, P.W. Roesky, S. Bambirra, A. Meetsma, B. Hessen, K. Saliu, J. Takats,
Organometallics 27 (2008) 1501.
[46] X.-S. Tai, Y.-M. Feng, F.-Y. Kong, D.-Q. Wang, M.-Y. Tan, Wuji Huaxue Xuebao
24 (2008) 831.
26] K.B. Yatsimirskii, M.G. Myskiv, A.S. Grigoreva, E.E. Kriss, E.I. Gladyshevskii,
Dokl. Akad. Nauk SSSR 247 (1979) 1204.
27] M.G. Myskiv, V.V. Olijnik, E.E. Kriss, N.F. Konakhovich, A.S. Grigor’eva, Koord.
Khim. 8 (1982) 1415.
28] D. Kovala-Demertzi, V. Dokorou, Z. Ciunik, N. Kourkoumelis, M.A. Demertzis,
Appl. Organomet. Chem. 16 (2002) 360.
29] S. Lorinc, M. Koman, M. Melnik, M. Jaroslava, Acta Crystallogr. E62 (2006)
m1938.
[47] F.H. Allen, Acta Cryst. B58 (2002) 380.
[48] R. Taylor, O. Kennard, J. Am. Chem. Soc. 104 (1982) 5063.
[49] G.R. Desiraju, T. Steiner, The Weak Hydrogen Bond in Structural Chemistry and
Biology, Oxford University Press, Oxford, 1999.
[50] L. Fang, S. Numajiri, D. Kobayashi, H. Ueda, K. Nakayama, H. Miyamae, Y.
Morimoto, J. Pharm. Sci. 93 (2004) 144.
30] G. Facchin, M.H. Torre, E. Kremer, O.E. Piro, E.J. Baran, Z. Naturforsch. B53
(
1998) 871.
31] N. Tahir, D. Ulku, M. Danish, S. Ali, A. Badshah, M. Mazhar, Acta Crystallogr. C53
1997) 183.
32] X-RED. Version 1.18. STOE & Cie GmbH, Darmstadt, Germany, 1999.
[51] R. Panchagnula, S. Prakash, O. Pillai, S. Agrawal, Y.S. Raj, J. Pharm. Sci. 93 (2004)
1019.
(
[52] H. Arslan, A. Sß engül, S. Aygün, N. Karadayi, S. Haman Bayari, J. Mol. Struct. 839
(2007) 76.