Isolation of a new anion, [CdBr4(C7H 5O2)]3 -: Synthesis, single crystal X-ray structure determination and DFT calculations of [Co(en)3][CdBr 4(C7H5O2)]?H2O

Article abstract of DOI:10.1016/j.inoche.2011.10.020

A new anion [CdBr₄(C₇H₅O ₂)]^{3 -}, where C₇H₅O₂ = benzoate, has been isolated for the first time in the form of complex salt [Co(en)₃] [CdBr₄(C₇H₅O ₂)]?H₂O(1). This is the first example where Cd(II) centre is coordinated by both inorganic and organic ligands and existing as discrete unit. The complex salt is characterized by spectroscopic techniques and single crystal X-ray crystallography. The formation of complex salt is also supported by DFT calculations.

Full text of DOI:10.1016/j.inoche.2011.10.020

Inorganic Chemistry Communications 15 (2012) 185–189
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Isolation of a new anion, [CdBr4(C7H5O2)]3−: Synthesis, single crystal X-ray structure
determination and DFT calculations of [Co(en)3][CdBr4(C7H5O2)]·H2O
a
a
a
b,⁎⁎
Raj Pal Sharma a, , Kusum Lata , Ajnesh Singh , Paloth Venugopalan , Valeria Ferretti
⁎
a
Department of Chemistry, Panjab University, Chandigarh-160014, India
Centro di Strutturistica Diffrattometrica and Dipartimento di Chimica, University of Ferrara via L. Borsari 46, I-44100, Ferrara, Italy
b
a r t i c l e i n f o
a b s t r a c t
A new anion [CdBr4(C7H5O2)]3−, where C7H5O2 = benzoate, has been isolated for the first time in the form of
complex salt [Co(en)3] [CdBr4(C7H5O2)]·H2O(1). This is the first example where Cd(II) centre is coordinated
by both inorganic and organic ligands and existing as discrete unit. The complex salt is characterized by spec-
troscopic techniques and single crystal X-ray crystallography. The formation of complex salt is also supported
by DFT calculations.
Article history:
Received 30 August 2011
Accepted 17 October 2011
Available online 25 October 2011
Keywords:
New anion
© 2011 Elsevier B.V. All rights reserved.
Benzoatotetrabromocadmate(II)
DFT calculations
X-ray crystallography
Research in the field of organic–inorganic hybrid compounds is of
great interest in chemistry and materials science because these com-
pounds represent the combined properties of both organic and inorgan-
ic compounds within a single entity. This enables them to exhibit some
interesting crystal structures and properties such as second-order non-
linear optical (NLO) response, magnetism, luminescence etc. [1–7].
Chemists often encounter the challenging task of design and later suc-
cessful synthesis of such new materials. Although it is still a dream,
but significant advances based upon analyses of large amount of exper-
imental data have enabled chemists to understand the rationale of syn-
thesis. A rational synthesis involves i) combination of reactants in
proper stoichiometeric ratio and ii) choice of a suitable method (sol–
gel, self assembly etc.). We have successfully exploited this strategy to
synthesize novel halogeno/pseudohalogenomercurate(II) anions [Hg2
(SCN)7]3− [8], [HgBr5]3− [9], [HgBr4Cl]3− [10] and polymeric halogen-
ocadmate(II) anion [Cd3Br10(H2O)2]4− [11] with the help of [Co(NH3)6]
Cl3/Br3. During the successful isolation of [HgBr4Cl]3− anion, we have
made an observation that it is possible to transfer bromide ions from
first coordination sphere of [HgBr5]3− by using the proper stoichiome-
try of halide ions. Adhering to the above hypothesis, it was envisaged
that it may be possible to synthesize new inorganic–organic hybrid ma-
terials in which one/few halide ions are replaced by appropriate organic
ligands. In the present investigation, an attempt has been made to uti-
lize complex salt [Co(en)3]Cl3 for the synthesis of new anionic inorganic
and organic hybrid material containing Cd(II) centre. Cadmium(II) is
the metal of choice as its complexes have demonstrated both chemical
and structural diversity [12,13], potential applications in catalysis, opti-
cal properties, [14–16] etc. while organic ligand selected was benzoate
anion because of its significance in food and preservative industry
[17,18].
Thus, we herein report our results of the reaction between [Co
(en)3]Cl3 with K2[CdBr4] and sodium benzoate. The reaction was car-
ried out by two different methods. In first method, [Co(en)3]Cl3 was
reacted with K2CdBr4 (formed by the reaction of KBr and CdBr2 in
aqueous medium) [19]. This resulted in the formation of crystalline
yellow coloured product which was further reacted with sodium ben-
zoate. In second method [Co(en)3]Cl3, K2[CdBr4] and sodium benzoate
were reacted in a single pot without attempting to isolate the crystal-
line yellow coloured product as it was done in the first method. It was
expected that reaction of [Co(en)3]Cl3 with K2CdBr4 would result in
[Co(en)3][CdBr4Cl] and its reaction with sodium benzoate can result
in a product where chloride may be replaced by benzoate ion. The
products (crystals) obtained in both the cases were identical as indi-
cated by melting point, elemental analyses and spectroscopic studies
(FT-IR, NMR and UV/Visible). The authenticity of the same reaction
product in both cases was confirmed by identical unit cell dimensions
of their respective crystals obtained through single crystal X-ray crys-
tallography. A schematic representation of the reaction procedure
used is given in the Scheme 1.
Solubility product measurements at room temperature showed
that complex salt 1 is less soluble in water as compared to tris(ethy-
lenediammine)cobalt(III)chloride. The Ksp values for 1 and [Co(en)3]
Cl3 are 1.5×10−3 and 195.3 respectively, indicating that the [Co
(en)3]3+ cation has more affinity for [CdBr4(C7H5O2)]3− as compared
⁎
Corresponding author. Tel.: +91 0172 2534433; fax: +91 0172 2545074.
⁎⁎ Corresponding author. Tel.: +39 0532 455144; fax: +39 0532 240 709.
E-mail addresses: rpsharmapu@yahoo.co.in (R.P. Sharma), frt@unife.it (V. Ferretti).
to Cl−
.
1387-7003/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2011.10.020

186
R.P. Sharma et al. / Inorganic Chemistry Communications 15 (2012) 185–189
Scheme 1. Schematic representation of reactions.
Conductance measurements were carried out at 25 °C in aqueous me-
transitions typical for low spin Co(III) d6 octahedral complexes while
a shoulder observed at 221 nm was due the aromatic ring of benzoate.
Single crystal X-ray structure determination was undertaken to
unambiguously establish the structure [26–31]. The crystal data and
refinement parameters are reported in Table 1. The asymmetric unit
of 1 consists of a tris(ethylenediamine)cobalt(III) complex cation,
counter-anion benzoatotetrabromo cadmate(II) and a water mole-
cule as solvent of crystallization. The ORTEPIII diagram [32] of com-
plex salt is shown in Fig. 1. The coordination geometry around the
Co(III) centre is slightly distorted octahedral mainly due to the ethy-
lenediamine bite. The selected bond lengths and bond angles are
reported in Table S1 in supplementary information. In the anion,
[CdBr4(C7H5O2)]3− the coordination around Cd(II) centre is five and
to the best of our knowledge [CdBr5]3− is surprisingly unknown
([CdBr4]2− and [CdBr6]4− are well documented in the literature), how-
ever analogous [CdCl5]3− exists [33]. The Cd(II) metal ion is bound to
four bromide and one oxygen of the benzoate moiety, leading to a dis-
torted square pyramidal geometry, in which the Cd(II) metal ion is lo-
cated 0.38 Å above the basal mean plane. The Br3 atom is in apical
position, and the angle formed by the Cd–Br3 line and normal to (Br1,
Br2, Br4, O2)-least-squares plane measures 176.08(3)°. In an effort to
classify the existing cadmium-benzoate complexes, a CSD search [34]
has been done on penta- and hexa-coordinated cadmium(II) complexes
containing the benzoate fragment (or its derivatives). Out of 55 penta-
coordinated complexes retrieved, in 18 cases the ligand acts as a biden-
tate towards the same metal atom and the Cd\O bond distances vary
in the range of 2.21–2.67 Å. In the present structure, however, the
Cd\O1 bond distance is 2.725(5) Å which is longer than the range ob-
served in CSD search. This may be due to the monodentate nature of
the benzoate anion which is unique in the present structure. In the
remaining 37 structures, the carboxylate group bridges two metal
centres.
dium and a graph was plotted between Λ (molar conductance) and
square root of concentration. The Λo value obtained was 536 S cm2 mol−1
for title complex salt which was closer to the values 561 and
531 S cm2 mol−1 reported for similar complex salt [Co(NH3)6][HgBr5]
[9] and [Co(NH3)6][HgBr4Cl] [10], respectively.
The FT IR spectrum of complex salt was recorded in the region
400–4000 cm−1. The IR absorption bands at 3501, 3357, 1556, 1408,
850, 738, 461 cm−1 were assigned to νas(N\H), ν(O\H), ν(C_C),
νs(N\H), r(NH2), δ(C\H), ν(Co\N) vibrations
. To distinguish
between the various bonding modes of carboxylate present in a
compound, the magnitude of separation between νas(COO−) and
νs(COO−), Δν (cm−1) is often used as diagnostic measure. The
infrared absorption bands observed at 1585, 1323 cm−1 were assigned
to νas(COO−) and νs(COO−), thus the value of Δν=262 cm−1. This indi-
cated the presence of monodentate carboxylate group [20–22].The FT IR
spectrum of complex salt is shown in Fig. S1 in supporting information.
1H and 13C NMR spectra of complex salt 1 were recorded in D2O. In
1H NMR, a doublet at 2.68 ppm was assigned to CH2 protons of ethyle-
nediamine groups of [Co(en)3]3+. Other three signals at 7.33, 7.41 and
7.72 ppm were assigned to the H3/5, H4 and H2/6 protons of benzoate
ring. 13C NMR spectrum showed the characteristic signal at 44.3 ppm
for carbon atoms of ethylenediamine groups of complex cation. Signals
at 135.6, 131.4, 128.8, 128.3, 175.81 ppm were assigned to carbon
atoms C1, C2/6, C3/5, C4, Ccarboxylate of the coordinated benzoate ligand
of complex anion [CdBr4(C7H5O2)]3− [20,23,24].
UV/Visible spectrum of the title complex salt was recorded in water
as a solvent. Two electronic transitions: 1A1g→T1g and 1A1g→ 1T2g have
been reported in literature for Co(III) containing complex salts around
470 and 340 nm, respectively [25]. For the title complex salt, the
strong absorption maxima (λmax) were observed at 466 (ε=89.9
mol−1L cm−1) and 338 (ε=88.31 mol−1 L cm−1) nm showing d–d
In the 298 structures (CSD) of hexacoordinated Cd(II) complexes
both the oxygen atoms are bound to Cd with bond lengths in the
range of 2.21–2.78 Å while 174 entries have been found with the ben-
zoate ligand classified as monodentate. Here, the Cd\O bond dis-
tances range from 2.14 to 2.56 Å. A further search of structures
containing the [CdX5]3− anion (X = any halogen) yielded only one
Hit, FOWLEJ [35] where the coordination geometry around the
metal ion is trigonal bipyramidal (as shown in Fig. 2).
DFT calculations have been performed on the Cd(II) complex
anion [36–40], starting from the geometry found in the crystal.
These calculations are of particular interest in view of the different
behaviour displayed by the complex when considered in vacuum
and in a simulated solvent (water). The optimization process in gas
phase failed, as it was not converging after 80 cycles; it is however
worth mentioning that the benzoate anion shows a tendency to dis-
sociate from the CdBr4 fragment, in the last cycle the carboxylate ox-
ygen atoms became 5 Å apart from Cd atom. The same results have
Table 1
Crystal data and refinement details of complex salt 1.
Crystal data
Chemical formula
Mr
Crystal system, space group
Temperature (K)
a, b, c (Å)
V (Å3)
(CdBr4C7H5O2)·(CoC6H24N6)·H2O
810.41
Orthorhombic, P212121
295
11.2045 (2), 11.7493 (2), 18.3147 (4)
2411.04 (8)
4
Mo Kα
8.22
Z
Radiation type
μ (mm−1
)
Crystal size (mm)
0.50×0.32×0.29
26232, 6995, 5712
No. of measured, independent and
observed [I>2σ(I)] reflections
Rint
0.055
0.044, 0.115, 1.03
6995/253
R[F2 >2σ(F2)], wR(F2), S
No. of reflections/no. of parameters
been obtained when optimization was started from
a hexa-
coordinated Cd atom, in which both oxygens were bound to the cen-
tral metal. On the contrary, in simulated water the complex did not
Δρmax, Δρmin (e Å−3
)
0.96, −0.90

R.P. Sharma et al. / Inorganic Chemistry Communications 15 (2012) 185–189
187
Fig. 1. ORTEPIII view and atom numbering scheme for complex salt 1. Thermal ellipsoids are drawn at the 40% probability level. Average bond distances are Co\N=1.966(6),
Cd\Br=2.7045(8), Cd–O2=2.309(5), C\O=1.248(8).
dissociate and assumed the geometry as shown in Fig. 3 (calculated
coordinates for the molecule are given in Table S2 in supporting infor-
mation). Here the two carboxylate oxygens were almost equidistant
from the central atom, and the coordination can be described as high-
ly distorted octahedral. The Cd–Br distances were longer than those
found in the crystal, being in the range of 2.77–2.87 Å, but in line
with the values found in the only structure containing the
[CdBr6]4− ion [41] which vary from 2.745 to 2.814 Å. Therefore, it
may be hypothesized that what found in the crystal is a snapshot of
an incipient association process of the carboxylate oxygen atoms to
the metal centre which however has to compete with the presence
of a water molecules forming hydrogen bonds with both the benzoate
oxygen atoms.
The packing architecture is quite complicated, in view of the large
number of available hydrogen-bond donors and acceptors. All N–H
groups of the ethylenediamine moieties are involved in hydrogen
bonds, whose structural parameters are reported in Table S3 in sup-
porting information. The strongest hydrogen bonds are however
made by the free water molecule, which acts as a donor towards O1
and O2 atoms of the benzoate anion and accepts a H\bond from
N5, as shown in Fig. 4(a), linking the alternately placed cations and
anions along the b direction. Besides these bonds, the crystal architec-
ture is made more robust by several weaker C\H…O/Br interactions.
Fig. 2. Coordination around the Cd atom in FOWLEJ.
Fig. 3. Optimized geometry in simulated solvent (water). Cd–O distances (Å) are shown.

188
R.P. Sharma et al. / Inorganic Chemistry Communications 15 (2012) 185–189
Fig. 4. (a) Molecular arrangement around the water molecule which is acting as linker between anion–anion and cation–anion. (b) Cell contents (viewed along a axis). Polyhedra
around the Co and Cd atoms are shown in blue and grey, respectively.
The overall packing pattern is shown in Fig. 4(b), where the com-
plexes are represented by their coordination polyhedra.
[7] P.G. Lacroix, R. Clement, K. Nakatani, J. Zyss, I. Ledoux, Stilbazolium-MPS3 nano-
composites with large second-order optical nonlinearity and permanent magne-
tization, Science 263 (1994) 658–660.
Thus, the synthesis of new a anion [CdBr4(C7H5O2)]3− has been de-
scribed which is isolated in the form of complex salt [Co(en)3][CdBr4
(C7H5O2)]·H2O for the first time. To the best of our knowledge, this
is the first structural report of five coordinated Cd(II) metal ion having
organic (benzoate) and inorganic (bromide) ligands attached to it and
exiting as a discrete anion. The formation of this new anion is facilitat-
ed by a cation [Co(en)3]3+ which can involve in second-sphere hydro-
gen bonding interactions i.e. N\H…O, C\H…O/Br besides electrostatic
forces of attraction.
[8] R.P. Sharma, R. Bala, R. Sharma, B.M. Kariuki, A New anion, [Hg2(SCN)7]3−: first
synthesis, spectroscopic characterization and X-ray structure determination of
[Co(NH3)6][Hg2(SCN)7], Inorg. Chem. Commun. 9 (2006) 852–855.
[9] R.P. Sharma, R. Sharma, A. Kumar, P. Venugopalan, P. Brando, V. Felix, First X-ray
structure of discrete anion [HgBr5]3−: synthesis, characterization and single crys-
tal X-ray structure determination of [Co(NH3)6][HgBr5], Inorg. Chem. Commun.
12 (2009) 945–947.
[10] R.P. Sharma, A. Singh, A. Saini, P. Venugopalan, V. Ferretti, A rational synthesis of
new anion [HgBr4Cl]3−
: synthesis, characterization and single crystal X-ray
structure determination of [Co(NH3)6][HgBr4Cl], Inorg. Chem. Commun. 14
(2011) 1–4.
[11] R.P. Sharma, R. Sharma, A. Singh, A. Saini, P. Venugopalan, A.I. Gubanov, A.I. Smolentsev,
Isolation of a new bromocadmate(II) anion stabilized by second sphere coordination:
[Co(NH3)6]2[Cd3Br10(H2O)2]Br2·2H2O, J. Mol. Struct. 980 (2010) 261–266.
[12] R.D. Willett, B. Twamley, Diethylammonium heptabromidedicadmium(II), Acta
Crystallogr. E57 (2001) m573–m575.
Appendix A. Supplementary material
[13] P.L. Goggin, R.J. Goodfellow, K. Kessler, Infrared and Raman spectra of di-μ-
halogeno-bis[dihalogenocadmate(II)] anions, J. Chem. Soc. Dalton Trans. (1977)
1914–1918.
[14] P. Ayyappan, O.R. Evans, W.B. Lin, A novel coordination polymer containing both
interdigitated 1D chains and interpenetrated 2D grids, Inorg. Chem. 41 (2002)
3328–3330.
[15] H. Zhu, M. Ströbele, Yu Zhi, Z. Wang, H.-J. Meyer, X. You, A blue luminescent di-2-
pyridylamine cadmium complex with an unexpected arrangement of thiocyanate
ligands: a supramolecular layered structure based on hydrogen bonds and π–π
stacking, interactions, Inorg. Chem. Commun. 4 (2001) 577–581.
[16] D. Deng, P. Liu, B. Ji, L. Wang, W. Fu, Cd2(tren)2(dl-alaninato)](ClO4)3: an efficient
water-compatible Lewis acid catalyst for chemo-, regio-, and diastereo-selective
allylation of various aldehydes, Tetrahedron Lett. 51 (2010) 5567–5570.
[17] F. Sauer, Special Report-New York State Agriculture Experimental Station, 1973,
p. 22.
Additional material available from the Cambridge Crystallographic
Data Centre, CCDC No. CCDC 816619, comprises the final atomic coordi-
nates from all atoms, thermal parameters, and a complete listing of
bond distances and angles. Copies of this information may be obtained
free of charge on application to The Director, 12 Union Road, Cambridge,
CB2, 2EZ, UK, fax: +44 1223 336 033, e-mail: data_request@ccdc.cam.
ac.uk or http://www.ccdc.cam.ac.uk. The supplementary material also
contains Fig. S1, Tables S1–3. Supplementary data to this article can be
found online at doi:10.1016/j.inoche.2011.10.020.
References
[18] J.R. Chipley, Sodium benzoate and benzoic acid, foods, Food Sci. Technol. 57
(1993) 11–48.
[1] D.B. Mitzi, Templating and structural engineering in organic–inorganic perov-
skites, J. Chem. Soc., Dalton Trans. (2001) 1–12.
[2] R. Martınez-Manez, F. Sancenon, M. Biyikal, M. Hecht, K. Rurack, Mimicking tricks
from nature with sensory organic–inorganic hybrid materials, J. Mater. Chem. 21
(2011) 12588–12604.
[3] J. Qin, C. Dai, D. Liu, C. Chen, B. Wu, C. Yang, C. Zhan, Influence of the molecular
configuration on second-order nonlinear optical properties of coordination com-
pounds, Coord. Chem. Rev. 188 (1999) 23–34.
[4] V. Chakravarthy, A.M. Guloy, Synthesis and structure of a new layered organic–
inorganic compound containing unique chains of PbI2, Chem. Commun. (1997)
697–698.
[5] M. Ogawa, K. Kuroda, Photofunctions of intercalation compounds, Chem. Rev. 95
(1995) 399–438.
[6] P.G. Lacroix, Organic nonlinear optical chromophores in an inorganic environ-
ment. Toward an interplay between magnetism, conductivity and nonlinear op-
tics, Chem. Mater. 13 (2001) 3495–3506.
[19] Synthesis of [Co(en)3][CdBr4(C7H5O2)].H2O (1): Tris(ethylenediammine)cobalt
(III) chloride (1 g, 0.0029 mol) was dissolved in 10 mL of water. In another beaker
0.787 g (0.0029 mol) of cadmium(II) chloride and 0.68 g (0.0058 mol) of KBr was
dissolved in 5 mL of water. Both the solutions were mixed and allowed to evap-
orate slowly. Orange-yellow coloured shining crystals started appearing after few
minutes, which were separated from mother liquor and dried in air. 0.5 g of
above product was dissolved in 10 mL of water and to this solution 5 mL aqueous
solution of 0.101 g sodium benzoate was added. The reaction solution was left for
slow evaporation at room temperature. Orange-yellow coloured crystals were
obtained after three days. These crystals were collected by drawing off the mother
liquor and air-dried (overall yield = 70%). The newly synthesized complex salt is
soluble in water, methanol, ethanol, DMSO but insoluble in common organic sol-
vents like acetone, chloroform and carbon tetrachloride. Solubility is 3.14 g/100
mL in water. Ksp = 1.5×10−3. Anal. Calcd. For [Co(en)3][CdBr4(C7H5O2)].H2O, Co,
7.28; C,19.25; H, 3.83; N, 10.36. Found: Co, 7.12; C, 18.95; H, 3.75, N, 10.26%. FT IR

R.P. Sharma et al. / Inorganic Chemistry Communications 15 (2012) 185–189
189
(KBr pellet): 35.01(m), 3357(m), 3194(b,s), 1585(s), 1556(s), 1408(s), 1323(m),
[30] L.J. Farrugia, WinGX suite for small-molecule single-crystal crystallography,
J. Appl. Crystallogr. 32 (1999) 837–838.
[31] M. Nardelli, PARST95 — an update to PARST: a system of Fortran routines for cal-
culating molecular structure parameters from the results of crystal structure an-
alyses, J. Appl. Crystallogr. 28 (1995) 659.
[32] M.N. Burnett, C.K. Johnson, ORTEPIII, Report ORNL-6895, Oak Ridge National
Laboratory, Oak Ridge, Tennessee, USA, 1996.
[33] F.A. Cotton, G. Wilkinson, C.A. Murillo, M. Buchman, Advanced Inorganic Chemistry,
6th Ed. John Wiley and Sons, New York, 1999.
1159(s), 1056(s), 850(s), 738(s), 494(w), 461(w) cm−1. UV/Vis (solution): λmax
466 nm (ε=89.94 L mol−1 cm−1), 338 nm (ε=88.31 L mol−1 cm−1
)
[20] I. Kaneska, H. Nishimura, K. Kanamori, K. Kawai, K. Ichimura, K. Waranabe, The
infra-red spectrum of [Co(en)3]Cl3·3T2O (en: ethylenediamine), Spectrochim.
Acta 43A (1987) 817–821.
[21] K.C. Patil, G.V. Chandrashekhar, M.V. George, C.N.R. Rao, Infrared spectra and
thermal decompositions of metal acetates dicarboxylates, Can. J. Chem. 46
(1968) 257–265.
[22] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds,
5th edition John Wiley and Sons, New York, 1997.
[34] F.H. Allen, The Cambridge Structural Database: a quarter of a million crystal struc-
tures and rising, Acta Crystallogr. B58 (2002) 380–388.
[23] R.M. Silverstein, F.X. Webster, Spectroscopic Identification of Organic Compounds,
6th Ed. John Wiley and Sons, New York, 2006.
[35] FOWLEJ, R.-J. Xu, 1,1′-{[1,1′-(Pyridinium-2,6-diyl)diethylidyne]diimino}diguanidinium
pentachloridocadmate(II) monohydrate, Acta Crystallogr. E65 (2009) m951.
[36] DFT calculations. The ‘in vacuum’ fully optimized geometry of Cd complex anion
has been obtained by density functional theory (DFT) calculations carried out at
the GGA/DNP level of theory [37] using the DMol3 module of Material Studio sys-
tem of programs. [38] Afterwards, the calculations have been repeated including
a continuum solvation model (CSM) [39] in which the solute molecule forms a
cavity within a dielectric continuum of permittivity ε that represents the solvent,
in this case water.
[37] M. Dolg, W. Liu, S. Kalvoda, Performance of relativistic density functional and ab
initio pseudopotential approaches for systems with high-spin multiplicities: gad-
olinium diatomics GdX (X = H, N, O, F, P, S, Cl, Gd), Int. Quantum Chem. 76
(2000) 359–370.
[38] J.P. Perdew, Y. Wang, Accurate and simple analytic representation of the electron-gas
correlation energy, Phys. Rev. B 45 (1992) 13244–13249.
[39] Material Studio Version 5.5, Accelrys Software Inc, 2010.
[40] J. Tomasi, M. Persico, Molecular interactions in solution: an overview of methods
based on continuous distributions of the solvent, Chem. Rev. 94 (1994)
2027–2094.
[24] H.O. Kalinowski, S. Berger, S. Braun, C13 Spectroscopy, John Wiley & Sons, New York,
1986.
[25] P. Hendry, A. Ludi, Structure, reactivity, spectra, and redox properties of cobalt
(iii) hexaamines, Adv. Inorg. Chem. 35 (1990) 117–198.
[26] X-ray crystallography: Single-crystal diffraction data for compound 1 were col-
lected on a Nonius Kappa CCD diffractometer equipped with a CCD detector
with graphite-monochromatized MoKα radiation (λ=0.71073 Å). All intensities
were corrected for Lorentz, polarization and absorption effects [27]. The structure
was solved by direct methods with the SIR97 program [28] and refined on F2 by
full-matrix least-squares methods with anisotropic non-H atoms. H atoms were
included at calculated positions and were riding on their parent atoms, with
the exception of those belonging to the water molecule, which were not included
in the refinement. All other calculations were accomplished using SHELX97 [29],
WINGX [30] and PARST [31]. Crystal data and selected refine details are given in
Table 1.
[27] R.H. Blessing, An empirical correction for absorption anisotropy, Acta Crystallgr.
A51 (1995) 33–38.
[28] A. Altomare, M.C. Burla, M. Camalli, G. Cascarano, C. Giacovazzo, A. Guagliardi, A.G.
Moliterni, G. Polidori, R. Spagna, SIR97: a new tool for crystal structure determination
and refinement, J. Appl. Crystallogr. 32 (1999) 115–119.
[41] POPMUCV.G. Krishnan, Dou Shi-qi, A. Weiss, Tetra(guanidinium) hexabromocad-
mate, crystal structure and bromine nuclear qudrupole, Z. Naturforsch. 49A
(1994) 223–233.
[29] G.M. Sheldrick, SHELX97, Program for Crystal Structure Refinement, University of
Göttingen, Germany, 1997.