[(C6H10)(NH3)2][Ni(H 2O)4C6H2(COO)4] ·4H2O - A coordination polymer with the chain-like polyanion {Ni(H2O)4[C6H2(COO) 4]2-}n

Article abstract of DOI:10.1002/zaac.200700139

Triclinic single crystals of [(C₆H₁₀)(NH ₃)₂][Ni(H₂O)₄C₆H ₂(COO)₄]·4H₂O have been prepared in aqueous solution at 55°C. Space group PI; (Nr. 2), a = 691.23(6), b = 924.84(5), c = 1082.43(7) pm, α = 74.208(6)°, β = 75.558(7)°, γ= 68.251(6)°, V = 0.60985(7) nm³, Z = 1. The Nickel(II) species, located on a crystallographic inversion centre, is coordinated in a trans-octahedral fashion by two oxygen atoms stemming from the centrosymmetric pyromellitate anions and four from water molecules (Ni-O 205.82(12) - 208.11(13) pm). The connection between Ni²⁺ and [C₆H ₂(COO)₄)]⁴ leads to infinite chain-like polyanions extending parallel to [101] with {Ni(H₂O) ₄[C₆H₂(COO)₄]^2-} _n composition. [(C₆H₁₀)(NH₃) ₂]²⁺-cations are accomodated between the chains, compensating for the negative charge of the polyanions. Thermogravimetric analysis in air showed that the loss of water of crystallisation occurs in two steps between 102 and 206 °C, corresponding to the loss of 6 and 2 water molecules per formula unit, respectively. The dehydrated sample was stable between 206 and 353 °C. Further decomposition yielded nickel(II) oxide (NiO).

Full text of DOI:10.1002/zaac.200700139

DOI: 10.1002/zaac.200700139
[(C6H10)(NH3)2][Ni(H2O)4C6H2(COO)4]·4H2O ؊ A Coordination Polymer with
the Chain-like Polyanion {Ni(H2O)4[C6H2(COO)4]2؊}n
Roberto Köferstein and Christian Robl*
Jena, Institut für Anorganische und Analytische Chemie der Friedrich-Schiller-Universität
Received March 22nd, 2007.
Abstract. Triclinic single crystals of [(C6H10)(NH3)2]-
[Ni(H2O)4C6H2(COO)4]·4H2O have been prepared in aqueous solu-
tion at 55 °C. Space group P1 (Nr. 2), a ϭ 691.23(6), b ϭ 924.84(5),
[(C6H10)(NH3)2]2ϩ-cations are accomodated between the chains,
compensating for the negative charge of the polyanions. Thermo-
gravimetric analysis in air showed that the loss of water of crystalli-
sation occurs in two steps between 102 and 206 °C, corresponding
to the loss of 6 and 2 water molecules per formula unit, respectively.
The dehydrated sample was stable between 206 and 353 °C. Further
decomposition yielded nickel(II) oxide (NiO).
¯
c ϭ 1082.43(7) pm, α ϭ 74.208(6)°, β ϭ 75.558(7)°, γ ϭ 68.251(6)°,
V ϭ 0.60985(7) nm3, Z ϭ 1. The Nickel(II) species, located on a
crystallographic inversion centre, is coordinated in a trans-octahe-
dral fashion by two oxygen atoms stemming from the centrosym-
metric pyromellitate anions and four from water molecules (NiϪO
205.82(12) Ϫ 208.11(13) pm). The connection between Ni2ϩ and
[C6H2(COO)4)]4Ϫ leads to infinite chain-like polyanions extending
Keywords: Nickel; Benzene-1,2,4,5-tetracarboxylic acid; trans-
cyclohexylamine; Coordination polymer
2Ϫ
¯
parallel to [101] with {Ni(H2O)4[C6H2(COO)4]
}
n
composition.
Multi-dentate complexing agents are very well suited to form
one-, two- and three-dimensional coordination polymers, if they
are linked to suitable metal cations. These coordination polymers
attract great interest due to their enormous structural variety and
the various concomitant properties. A rational approach in syn-
thesis requires systematic structural studies in order to shed light
on the structure-governing principles. To this end we have em-
ployed anions of benzene carboxylic acids such as the tetraanion
of pyromellitic acid (benzene-1,2,4,5-tetracarboxylic acid), which
are capable of forming one-, two- or three-dimensionally infinite
connections between cations and anions. Thus we have obtained
chain structures, layered compounds, and three-dimensional frame-
works as well [1Ϫ20]. Particularly appealing are three-dimensional
framework structures with voids like those found in zeolites and
molecular sieves [14]. In order to control the structural features it
is possible to use template molecules such as amines. Thus, e.g.,
the characteristic feature in {Cu2[Cu(H2O)4][(CH2)4(NH3)2]-
Experimental Section
Single crystals of [(C6H10)(NH3)2][Ni(H2O)4C6H2(COO)4]·4H2O
were obtained by crystallization in aqueous solution at 55 °C. 5 ml
0.1 M Ni(NO3)2-solution, 5 ml 0.2 M trans-1,4-Diaminocyclo-
hexane-solution and 5 ml 0.05 M Na4C6H2(COO)4-solution were
combined. A temporarily occurring precipitate could be resolved
by addition of 2N HNO3. Afterwards 0.2 g urea was added. Spar-
ingly soluble, light-green column-shaped crystals appeared after
two days.
Elemental analysis: C16H34N2NiO16 (569.19) C 33.63 (calc. 33.77),
H 6.02 (6.09), N 4.92 (4.90) %
Characteristic IR absorption bands occur at 2944 and 2869 cmϪ1
(C-H), 1564 and 1528 cmϪ1 (C-O), and 1372 cmϪ1 (N-C).
Thermal analysis: This was carried out in air using a Netzsch STA-
429 device, revealing that water of crystallizationwas evolved endo-
thermically in two steps between 102 and 206 °C. The first step
corresponds to a loss of 6H2O per formula unit, the further 2H2O
were released in the second step. The dehydrated sample was stable
up to approx. 320 °C. Several exothermic decomposition steps fol-
lowed, essentially complete at 420 °C yielding NiO, which was
identified by X-ray powder diffraction.
[C6H2(COO)4]2}·4H2O [20] is
a three-dimensional framework
with negative excess charge and channel-like voids, which acco-
modate water molecules and [(CH2)4(NH3)2]2ϩ-cations. Here we
report on the use of pyromellitate tetraanions, with trans-cyclo-
hexyldiammonium cations as template agents, yielding
[(C6H10)(NH3)2][Ni(H2O)4C6H2(COO)4]·4H2O, which is charac-
terised
by
infinite
chain-like
polyanions
of
{Ni(H2O)4[C6H2(COO)4]2Ϫ}n composition.
X-ray diffraction intensities up to θmax ϭ 25° have been collected
at room temperature using a Siemens P4 four-circle diffractometer
with graphite-monochromatized MoKα-radiation, λ ϭ 71.07 pm.
A numerical absorption correction has been applied. The phase
problem was solved by direct methods. Difference Fourier-maps
revealed positions of hydrogen atoms, which were included in the
final cycles of refinement with isotropic displacement parameters.
Crystallographic data are given in Table 1. Further details con-
cerning the crystal structure analysis have been deposited with
* Prof. Dr. Christian Robl
Friedrich-Schiller-Universität Jena
Institut für Anorganische und Analytische Chemie
August-Bebel-Str. 6Ϫ8
D-07743 Jena/Germany
Fax ϩϩ49 (0)3641 948152
e-mail crr@uni-jena.de
Z. Anorg. Allg. Chem. 2007, 633, 1323Ϫ1325
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1323

R. Köferstein, Ch. Robl
Table 1 Crystallographic Data for [(C6H10)(NH3)2][Ni(H2O)4-
C6H2(COO)4]·4H2O
Table 2 Interatomic Distances /pm
The Ni2ϩ environment:
Formula
Crystal system
Space group
C16H34N2NiO16
triclinic
P1 (no.2)
Ni-O(w1) 205.96(14) (2x)
Ni-O(3) 205.82(12) (2x)
Ni-O(w2) 208.11(13) (2x)
¯
Unit cell dimensions
a ϭ 691.23(6) pm
b ϭ 924.84(5) pm
c ϭ 1082.43(7) pm
α ϭ 74.208(6)°
β ϭ 75.558(7)°
γ ϭ 68.251(6)°
0.60985(7) nm3
1
Pyromellitate Anion:
C(4)-C(5) 139.9(3)
C(4)-C(6) 139.4(3)
C(5)-C(6) 138.8(3)
C(4)-C(7) 151.1(2)
C(5)-C(8) 150.8(2)
C(7)-O(1) 126.7(2)
C(7)-O(2)
C(8)-O(3)
C(8)-O(4)
124.1(2)
126.9(2)
124.3(2)
Unit cell volume
Formulas in unit cell
Formula weight
trans-Cyclohexyldiammonium-cation:
569.16 g/mol
N-C(1)
149.4(3)
C(1)-C(3) 151.8(3)
C(2)-C(3) 153.1(3)
Density (calc.)
1.550 g/cm3
C(1)-C(2) 152.0(3)
Absorption coefficient
Absorption correction
min./max. transmission
Temperature
0.875 mmϪ1
face-indexed numerical
0.90/0.94
293(2) K
Crystal size
F (000)
0.08 mm x 0.12 mm x 0.70 mm
1392
well and is essentially planar with respect to its carbon atoms. The
largest deviation from a plane fitted to the carbon skeleton of the
anion is 4.2 pm at C(6). The carboxylate groups are inclined to the
plane of the C6 ring by 51.4° (C(7), O(1), O(2)) and 50.9° (C(8),
O(3), O(4), Fig. 1), respectively. The C-O bond lengths, ranging
from 124.1(2) to 126.9(2) pm show no significant difference be-
tween those of the oxygen atoms bound to Ni2ϩ and the others
(Table 2), indicating an essentially unperturbed delocalization of
the π-electrons.
Limiting indices
Ϫ1 Յ h Յ 8, Ϫ10 Յ k Յ 10, Ϫ12 Յ l Յ 12
2710
2129 (Rint ϭ 0.0144)
Direct methods
Full-matrix-LS on ΗFΗ2
216
Reflections collected
Independent reflections
Structure solution
Structure refinement
Refined parameters
Extinction parameter
Residuals (all data)
0.0027(11)
R1 ϭ 0.0284
wR2 ϭ 0.0545
Max. features in last difference
Fourier synthesis
Program
ϩ261/Ϫ203 e/nm3
SHELXTL [23]
Ni2ϩ and [C6H2(COO)4]4Ϫ form infinite chain-like polyanions of
{Ni(H2O)4[C6H2(COO)4]2Ϫ
¯
} composition extending in the [101]
n
direction (Fig. 2). These chains are stacked in an ...AAA... se-
quence in the [010] direction. The linear charge density is 0.177 e/
Cambridge Crystallographic Data Centre, The Director, CCDC, 12
Union Road, Cambridge CB21EZ, UK, Fax ϩ(1223)336-033,
˚
A, expressed in a more convenient manner as length/unit charge,
e-mail
data_request@ccdc.cam.ac.uk,
www.ccdc.cam.ac.uk/
˚
is 5.6 A/unit charge. The negative charge is compensated for by
data_request.cif under CCDC 640703.
[(C6H10)(NH3)2]2ϩ-cations intercalated between neighbouring
chains. The [(C6H10)(NH3)2]2ϩ-cation adopts a chair conformation
(Fig. 1) and is disposed about a crystallographic inversion centre,
with approximate symmetry C2h. The CϪC bond lengths range
from 151.8(3) pm to 153.1(3) pm and the C(1)ϪN bond is slightly
shorter (149.4(3) pm).
Results and Discussion
The nickel cation occupies a crystallographic inversion centre of
¯
space group P1 (Wyckoff-position 1a) and is coordinated
octahedrally in a moderately distorted fashion. Water molecules
(2 x O(w1), 2 x O(w2)) make up the equatorial plane. Oxygen atoms
stemming from the pyromellitate tetra-anion (2 x O(3)) occupy api-
cal positions. The NiϪO bond lengths differ over the range from
205.8(1) to 208.1(1) pm with no significant difference between
those of the water molecules and those of the oxygen atoms of the
carboxylate groups (Table 2). Their bond order (1.96) calculated
by the method of Brown [21] is close to the expected value. The
pyromellitate tetra-anion is disposed about an inversion centre as
A similar chain-like polycation {Mn(H2O)4(pyz)2ϩ
} is the domi-
n
nant feature in Mn(pyz)[C6H4(COO)2]·4H2O [22] with a higher
˚
charge density of 3.7 A/unit charge. Chain-like polyanions
{Co(H2O)4[C6H2(COO)4]2Ϫ
} occur as well in dicobaltpyromellit-
n
ate-octadecahydrate (Co2[C6H2(COO)4]·18H2O) [3, 10] with the
same linear charge density as in {Ni(H2O)4[C6H2(COO)4]2Ϫ}n.
However, there, the negative charge is compensated for by
[Co(H2O)6]2ϩ octahedra between adjacent chains.
Fig. 1 The [C6H2(COO)4]4Ϫ anion and the trans-cyclohexyldiammonium-cation. (50 % probability ellipsoids, arbitrary radii for hydro-
gen atoms.)
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 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2007, 1323Ϫ1325

[(C6H10)(NH3)2][Ni(H2O)4C6H2(COO)4]·4H2O
Fig. 2 The crystal structure of[(C6H10)(NH3)2][Ni(H2O)4C6H2(COO)4]·4H2O viewed from [100]. [(C6H10)(NH3)2]2ϩ cations and water
molecules (O(w3) and O(w4)) are intercalated between neighbouring chains.
[2] S. R. Batten, R. Robson, Angew. Chem. 1998, 110, 1558; An-
gew. Chem. Int. Ed. Engl. 1998, 37, 1460.
[3] D. Poleti, L. Karanovic, Acta Crystallogr. 1989, C45, 1716.
[4] R. D. Fulton, R. R. Ryan, J. H. Hall, Acta. Crystallogr. 1990,
C46, 1621.
Table 3 Hydrogen-Bonds /pm
N···O Distances (pm)
N-H(1)···O(w3)
N-H(2)···O(w4)
291.1
284.2
N-H(3)···O(w2)
N-H(3)···O(3)
290.1
289.1
[5] R. Cao, D. Sun, Y. Liang, M. Hong, K. Tatsumi, Q. Shi, Inorg.
Chem. 2002, 41, 2087.
O···O Distances (pm)
O(w1)-H(11)···O(1)
O(w1)-H(12)···O(2)
O(w2)-H(21)···O(4)
O(w2)-H(22)···O(1)
282.4
263.8
268.3
273.1
O(w3)-H(32)···O(4)
O(w4)-H(41)···O(w3)
O(w4)-H(42)···O(1)
273.5
289.2
283.1
[6] C. Robl, Z. Anorg. Allg. Chem. 1987, 554, 79.
[7] C. Robl, Z. Anorg. Allg. Chem. 1988, 561, 57.
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[10] C. Robl, S. Hentschel, Mat. Res. Bull. 1991, 26, 1355.
[11] C. Robl, Mat. Res. Bull. 1992, 27, 99.
The additional uncoordinated water molecules (O(w3) and O(w4))
stabilize the crystal structure by hydrogen-bonding. The NH3
ϩ
-
[12] S. Hentschel, Dissertation, Univ. München 1993.
[13] M. Arnold, Dissertation, Univ. Jena 1998.
groups of the [(C6H10)(NH3)2]2ϩ cations act as proton donors for
O(w2), O(w3), O(w4) and the carboxylate oxygen atom O(3). Those
carboxylate oxygen atoms that are not bound to Ni2ϩ act as proton
acceptors in hydrogen bonds. O(w3) and O(w4) are linked to each
other by hydrogen bonding. The O···O distances range from 263.8
to 289.2 pm indicating hydrogen-bonds of high and medium
strength (Tab. 3).
[14] R. Köferstein, Dissertation, Univ. Jena 2003.
[15] R. Köferstein, C. Robl, Z. Anorg. Allg. Chem. 2003, 629, 2186.
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[17] C. Robl, in: Chemistry at the Beginning of the Third Millen-
nium, L. Fabrizzi, A. Poggi (Hrsg.), Springer-Verlag, Berlin
2000, S. 279.
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[19] D. J. Duchamp, R. E. Marsh, Acta Crystallogr. 1969, B25, 5.
[20] R. Köferstein, C. Robl, Z. Anorg. Allg. Chem. 2003, 629, 1374.
[21] I. D. Brown, K. K. Wu, Acta Crystallogr. 1976, B32, 1957.
[22] R. Köferstein, C. Robl, Z. Anorg. Allg. Chem. 2007, in press.
[23] G. M. Sheldrick, SHELXTL, Bruker AXS Inc., Madison,
Wisconsin, USA, 1994.
Acknowledgement. We are grateful to Fonds der Chemischen Indus-
trie for financial support.
[1] P. J. Hagrman, D. Hagrman, J. Zubieta, Angew. Chem. 1999,
111, 2798; Angew. Chem. Int. Ed. Engl. 1999, 38, 2638.
Z. Anorg. Allg. Chem. 2007, 1323Ϫ1325
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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