A new layered organically templated iron(II) phosphite, (C 2H10N2)[Fe3(HPO3) 4]. Hydrothermal synthesis, crystal structure and spectroscopic and magnetic properties

Article abstract of DOI:10.1016/j.jssc.2004.04.020

The (C₂H₁₀N₂)[Fe₃(HPO ₃)₄] compound has been synthesized by using mild hydrothermal conditions under autogeneous pressure and the ethylenediamine molecule as templating agent. The compound crystallizes in the triclinic P1 space group with unit-cell parameters a=5.416(1), b=5.416(1), c=13.977(2)A, α=80.64(2), β=85.25(1), γ=60.03(1)°and Z=1. The final R-factors were R₁=0.053 [wR₂=0.092]. The crystal structure is constructed of layers stacked along the c-axis. The sheets contain FeO₆ octahedra linked by (HPO₃)^2- phosphite oxoanions to give rise to Fe₃O₁₂ trimeric units sharing faces. The IR spectrum shows the characteristic bands of the phosphite and ethylenediammonium ions. From the diffuse reflectance spectrum, the Dq parameter of 805cm^-1 has been calculated for the iron(II) cation in slightly distorted octahedral geometry. The Moessbauer spectrum exhibits two doublets characteristic of two crystallographically independent iron(II) ions in octahedral symmetry. Magnetic measurements indicate the existence of antiferromagnetic interactions.

Full text of DOI:10.1016/j.jssc.2004.04.020

ARTICLE IN PRESS
Journal of Solid State Chemistry 177 (2004) 2705–2713
A new layered organically templated iron(II) phosphite,
ðC H N Þ½Fe ðHPO Þ Š: Hydrothermal synthesis, crystal structure
1
0
2
2
3 3 4
and spectroscopic and magnetic properties
a
U-Chan Chung, Jose L. Mesa, * Jose L. Pizarro, Luis Lezama, Jose S. Garitaonandia,
´ ´ ´
b,
a
b
c
b
Jon P. Chapman, and Marıa I. Arriortua
´
a
a
Facultad de Ciencia y Tecnologia, Departamento de Mineralogı ´a -Petrologı´a, Universidad del Paı ´s Vasco, Apdo. 644, E-48080 Bilbao, Spain
b
Facultad de Ciencia y Tecnologia, Departamento de Quı´mica Inorg a´ nica, Universidad del Paı´s Vasco, Apdo. 644, E-48080 Bilbao, Spain
Facultad de Ciencia y Tecnologia, Departamento de Fı´sica Aplicada II, Universidad del Paı´s Vasco, Apdo. 644, E-48080 Bilbao, Spain
c
Received 19 November 2003; received in revised form 30 January 2004; accepted 4 April 2004
Abstract
The ðC H10N2Þ½Fe ðHPO Þ Š compound has been synthesized by using mild hydrothermal conditions under autogeneous pressure
2
3
3 4
%
and the ethylenediamine molecule as templating agent. The compound crystallizes in the triclinic P1 space group with unit-cell
ꢀ
˚
parameters a ¼ 5:416ð1Þ; b ¼ 5:416ð1Þ; c ¼ 13:977ð2Þ A, a ¼ 80:64ð2Þ; b ¼ 85:25ð1Þ; g ¼ 60:03ð1Þ and Z ¼ 1: The final R-factors
were R1 ¼ 0:053 [wR2 ¼ 0:092]. The crystal structure is constructed of layers stacked along the c-axis. The sheets contain FeO
6
2
)
À
phosphite oxoanions to give rise to Fe
characteristic bands of the phosphite and ethylenediammonium ions. From the diffuse reflectance spectrum, the Dq parameter of
octahedra linked by (HPO
3
3
O12 trimeric units sharing faces. The IR spectrum shows the
À1
8
05 cm has been calculated for the iron(II) cation in slightly distorted octahedral geometry. The Mo
¨
ssbauer spectrum exhibits two
doublets characteristic of two crystallographically independent iron(II) ions in octahedral symmetry. Magnetic measurements
indicate the existence of antiferromagnetic interactions.
r 2004 Elsevier Inc. All rights reserved.
¨
Keywords: Hydrothermal synthesis; X-ray diffraction; IR; UV/vis; Mossbauer; Magneticbehavior
1
. Introduction
role in templating novel networks [4] such as oxides,
phosphates, phosphonates with a large variety of
transitions metal ions [2].
The use of organic oc mpounds as templates when
combined with different oxoanions, such as, phosphates,
arsenates, phosphites for the generation of inorganic
structures and materials, has received increasing atten-
tion over the last decade [1]. The transfer of a variety of
organictemplates to the inorganicprodu ct s allows the
formation of otherwise unattainable inorganicstru-c
tures [2]. A frequently used concept in seeking systema-
tictrends in this area of materials ch emistry is that of
templating, the tendency of a cation to direct the
reaction to form a particular product [3]. In this way,
small organic molecules, particularly those containing
protonated amino groups, have played an outstanding
For over half a century, zeolites have played a major
role in the development of modern processes in the
chemical and petroleum industries [5]. Their unique
combination of physical and chemical properties is ideal
for catalysis and separations for a broad range of
molecules. The types of microporous materials, tetra-
hedral- and mixed-framework compounds, with open
structures continue to expand in terms of framework-
forming elements [2]. The most studied and also largest
classes of tetrahedral-framework compounds are alumi-
no-silicates [6], aluminophosphates [7], as well as their
isomorphicsubstituted forms. Attempts to synthesize
frameworks with elements other than Al, Si and P,
especially with transition metals, have resulted in many
new classes, such as gallophosphates, titanosilicates and
*Corresponding author. Fax: 34-946013500.
E-mail address: qipmeruj@lg.ehu.es (J.L. Mesa).
0022-4596/$ - see front matter r 2004 Elsevier Inc. All rights reserved.
doi:10.1016/j.jssc.2004.04.020

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U.-C. Chung et al. / Journal of Solid State Chemistry 177 (2004) 2705–2713
2706
beryllium, zinc, cobalt, iron, vanadium, nickel and
molybdenum phosphates [8]. Furthermore, compared
with tetrahedral elements in zeoliticaluminum sili-
cates (or phosphates), divalent transition metals have
a greater coordination flexibility and a stronger ten-
dency to form edge-sharing linkages of metal-oxygen
polyhedra.
of the reaction was 85%. The percentage of the elements
in the product was calculated by inductively coupled
plasma atomic emission spectroscopy (ICP-AES) to-
gether with C, H, N-elemental analysis. Found: Fe, 30.1;
P, 22.1; C, 4.2; H, 2.4; N, 5.0. ðC H10N2Þ½Fe ðHPO Þ Š
2
3
3 4
requires Fe, 30.5; P, 22.6; C, 4.4; H, 2.5; N, 5.1. The
À3
density of 2.6(1) g cm was measured by flotation in a
mixture of CHCl =CHBr : A simulation using the
3
3
Among these materials the organically templated
iron(III)-phosphates occupy a major position. A num-
ber of works dealing with this system has evidenced a
considerable structural and compositional diversity [9],
being scarce the iron(II) phases. The structural chem-
istry of phosphite with elements of the first transition
series reveals complex two-dimensional and three-
dimensional phases [10]. The inorganic–organic hybrid
phosphites with metallictransition elements, however,
have not been extensively studied, and only compounds
with the V(IV), Co(II), Mn(II), Fe(II, III), V(III),
Cr(III) cations are known [11]. It is worth mentioning
pattern matching routine of the FULLPROF program
1
[12], based on the single crystal structure, was in
excellent agreement with the X-ray powder data,
indicating the presence of a pure phase with high
crystallinity.
Thermogravimetricanalysis of ðC H10N2Þ½Fe ðHPO Þ Š
2
3
3 4
was carried out under oxygen atmosphere in an SDC
2960 Simultaneous DSC-TGA TA Instrument. Cruci-
bles containing ca. 20 mg of sample were heated at
ꢀ
À1
ꢀ
5 C min
decomposition curve reveals a weight loss of 6.2% with
in the temperature range 30–800 C. The
II
ꢀ
ꢀ
that in the ðC H10N2Þ½M3ðHPO Þ Š (M =Mn and Co)
superimposed steps between ca. 200 C and 680 C, which
correspond to the calcination of the ethylenediammo-
nium dication and the oxidation of the phosphite
oxoanion to the phosphate groups, respectively. The
X-ray diffraction pattern of the residue obtained after
2
3 4
family of compounds in which, the metallic cations have
similar ionicradius, the protonated ethylenediamine
molecule acts as structure directing agent to obtain the
same type of layered structural framework [11b,d]. In
order to improve the understanding about this type of
microporous materials incorporating metallic magnetic
cations belonging to the first series of transition
elements, we have synthesized the phosphite of formula
ðC H10N2Þ½Fe ðHPO Þ Š: In the present work, we report
ꢀ
the thermogravimetricanalysis at 800 C shows the
presence of trigonal Fe(PO ) [P3121; a ¼ 5:03ð1Þ;
4
˚
c ¼ 11:23ð1Þ A] [13a].
The thermal behavior of ðC H10N2Þ½Fe ðHPO Þ Š was
2
3
3 4
also studied using time-resolved X-ray thermodiffracto-
metry in air atmosphere. A PHILIPS X’PERT auto-
maticdiffra ct ometer (Cu Ka radiation) equipped with a
variable-temperature stage (Paar Physica TCU2000)
with a Pt sample holder was used in the experiment.
2
3
3 4
the synthesis, crystal structure and the thermal and
spectroscopic and magnetic properties.
ꢀ
2
. Experimental section
The powder patterns were recorded in 2y steps of 0.02
ꢀ
in the range 4p2yp40 ; counting for 1 s per step and
ꢀ
À1
from room
temperature up to 815 C (Fig. 1). The compound is
2
.1. Synthesis and characterization
The ðC H10N2Þ½Fe ðHPO Þ Š phase was synthesized
increasing the temperature at 5 C min
ꢀ
ꢀ
stable up to ca. 195 C and the intensity of the monitored
ꢀ
2
under mild hydrothermal conditions starting from
3
3 4
(001) peak at 2y ¼ 6:4 remains practically unchanged.
ꢀ
reaction mixtures of FeCl Á 6H O (5.55 mmol), H PO
At around 315 C a strong decrease of the intensity of
this peak takes place (ca. 85% of the initial intensity)
starting the decomposition of the compound. Between
3
2
3
2
hypophosphorous acid (144.8 mmol) and ethylenedi-
amine (0.269 mmol) in a volume of 10 mL of water. The
mixture was stirred to assure homogeneity, sealed in a
ꢀ
ꢀ
315 C and 500 C no peaks were observed in the
ꢀ
PTFE-lined stainless steel pressure vessel (fill factor
ꢀ
patterns. At temperatures higher than ca. 510 C peaks
belonging to the trigonal [P3121; a ¼ 5:03ð1Þ;
7
5%) and heated at 170 C for 5 days, followed by slow
˚
cooling to room temperature. The pH of the reaction
mixture did not show any appreciable change during the
hydrothermal reaction and remained at ca. 6.0. This
value of pH allows the protonation of the ethylenedia-
mine molecule, incorporated in the form of ethylene-
c ¼ 11:23ð1Þ A] [13a] and orthorhombic[ Cmcm; a ¼
˚
5:23ð1Þ; b ¼ 7:70ð1Þ; c ¼ 6:32ð1Þ A] [13b] Fe(PO ) poly-
4
morphs are observed. The peaks of the orthorhombic
ꢀ
Fe(PO ) disappear at 585 C and those of Fe (P O )
2
4
4
7 3
ꢀ
appear at 720 C [13c]. These results indicate that the loss
of the ethylenediammonium cation gives rise to the
collapse of the layered architecture and subsequent
formation of various iron(III) phosphates.
2
À
diammonium cations, between the [Fe (HPO ) ]
3
3 4
inorganicsheets establishing both hydrogen bonds and
ionicintera ct ions with these layers. Well formed light-
green single-crystals appeared at the end of the
synthesis. They were isolated by filtration, washed with
water and acetone and dried over P O for 2 h. The yield
1
The program is a strongly modified version of that described by
D.B. Wiles and R.A. Young.
2
5

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U.-C. Chung et al. / Journal of Solid State Chemistry 177 (2004) 2705–2713
2707
Fig. 1. Thermodiffractograms of ðC H10N2Þ½Fe ðHPO Þ Š:
2
3
3 4
Table 1
Crystallographicdata for (C
2
.2. Single-crystal X-ray diffraction
2
H
10
N
2
)[Fe
3 3 4
(HPO ) ]
A prismaticsingle- cr ystal of ðC H10N2Þ½Fe ðHPO Þ Š
Chemical formula
C H N O12P4Fe3
2
2
3
3 4
2
14
3
À1
Molecular weight (g mol
Crystal system
Space group
)
549.60
Triclinic
P 1% (no. 2)
with dimensions 0.1 Â 0.05 Â 0.05 mm was carefully
selected under a polarizing microscope and mounted
on a glass fiber. Diffraction data were collected at room
temperature on an Enraf-Nonius CAD4 automated
diffractometer using graphite-monochromated MoKa
radiation. Details of the crystal data, intensity collection
and some features of the structure refinement are
reported in Table 1. Lattice constants were obtained
by a least-squares refinement of the setting angles of 25
˚
a (A)
5.416(1)
5.416(1)
13.977(2)
80.64(2)
85.25(1)
60.03(1)
350.4(1)
1
˚
b (A)
˚
c (A)
a ( )
ꢀ
ꢀ
b ( )
ꢀ
g ( )
Volume (A )
3
˚
Z
ꢀ
ꢀ
À3
)
reflections in the range 1 oyo30 : Intensities and
angular positions of two standard reflections were
measured every hour and showed neither decrease nor
misalignment during data collection.
rcalcd. (g cm
F(000)
T (K)
2.604
274
293
0.71073
3.587
˚
Radiation, l(MoKa) (A)
À1
m (MoKa) (mm
Limiting indices
R½I42sðIފ
R [all data]
Goodness of fit
P
)
A total of 1579 reflections were measured in the range
:48p2yp26:36 of which 1426 were independent
À6php5; À6pkp0; À17plp17
R ¼ 0:035; wR ¼ 0:085
1
(
1
2
R1 ¼ 0:053; wR2 ¼ 0:092
Rint: ¼ 0:027) and 1179 observed applying the criterion
1.047
I42sðIÞ: Corrections for Lorentz and polarization
effects were made and also for absorption with the
empirical c scan method [14] using the X-RAYACS
program [15]. Direct methods (SHELXS 97) [16] were
employed to solve the structure. The metal ions and the
phosphorous atoms were first located. The oxygen,
nitrogen, and carbon atoms were found in difference
Fourier maps. In the crystal structure exist two crystal-
lographically independent iron(II) cations. The Fe(1)
ion occupies a special position with an occupancy factor
of 0.5. The structure was refined by the full-matrix least-
P
P
P
2
2
2
2 2 1=2
R ¼½ ðjF jÀjF jފ= jF j; wR ¼½ ½wðjF jÀjF j Þ Š= ½wðjF j Þ Š
1
o
c
o
2
o
c
o
;
2
2
2
2
2
w ¼ 1=½s jFoj þ ðxpÞ Š; where p ¼ ½jFoj þ 2jFcj Š=3; and x ¼ 0:065:
2
squares method based on F ; using the SHELXL 97
computer program [17]. The scattering factors were
taken from Ref. [18]. All non-hydrogen atoms were
assigned anisotropicthermal parameters. The oc ordi-
nates of hydrogen atoms of the phosphite anion were
obtained from difference Fourier maps and those of the

ARTICLE IN PRESS
U.-C. Chung et al. / Journal of Solid State Chemistry 177 (2004) 2705–2713
2708
Table 2
Fractional atomic coordinates and equivalent isotropic thermal
Table 3
Selected bond distances (A) and angles ( ) for (C
(e.s.d. in parentheses)
˚
ꢀ
2
H
10
N
2
)[Fe
3
3
(HPO )
4
]
2
3
˚
parameters (A Â 10 ) for (C
2
H
10
N
2
)[Fe
3
3
(HPO )
4
] (e.s.d. in parenth-
eses)
˚
Bond distances (A)
Atom
x=a
y=b
0.5000
z=c
Ueq
Fe(1)O
6
octahedron
6
Fe(2)O octahedron
i
Fe(1)–O(1) /O(1)
ii
ii
ii
i
2.168(3)
2.170(3)
2.171(3)
Fe(2)–O(1)
Fe(2)–O(2)
Fe(2)–O(3)
Fe(2)–O(4)
Fe(2)–O(5)
Fe(2)–O(6)
2.229(3)
2.242(3)
2.229(2)
2.072(3)
2.066(3)
2.069(3)
Fe(1)
Fe(2)
P(1)
0.0
0.0
11(1)
i
Fe(1)–O(2) /O(2)
i
Fe(1)–O(3) /O(3)
ii
i
0.0008(1)
0.6671(1)
0.6649(2)
0.8189(6)
0.6471(6)
0.8304(6)
0.3582(6)
0.7913(6)
0.8490(6)
0.3330(7)
0.3651(9)
0.4107(1)
1.1979(2)
0.0567(2)
0.8944(6)
0.6267(6)
0.3608(6)
0.2231(6)
0.7340(6)
0.1659(6)
0.6772(7)
0.6347(9)
0.2110(1)
À0.0743(1)
0.2633(1)
À0.1019(2)
0.1019(2)
À0.1022(2)
0.2983(2)
0.2968(2)
0.2968(2)
0.3779(2)
0.4842(3)
10(1)
10(1)
9(1)
P(2)
ii
ii
O(1)
O(2)
O(3)
O(4)
O(5)
O(6)
N(1)
C(1)
16(1)
16(1)
16(1)
14(1)
16(1)
13(1)
14(1)
21(1)
iii
Fe(1)–Fe(2)/Fe(2)
2.9096(7)
HP(1)O tetrahedron
3
3
HP(2)O tetrahedron
P(1)–O(1)
P(1)–O(2)
P(1)–O(3)
1.527(3)
1.524(3)
1.524(3)
1.31(2)
P(2)–O(4)
P(2)–O(5)
P(2)–O(6)
1.524(3)
1.528(3)
1.523(3)
1.30(2)
iv
vi
v
H(11)–P(1)
H(22)–P(2)
2
2
2
Ueq ¼ ð1=3Þ½U11ðaaꢁÞ þ U22ðbbꢁÞ þ U33ðccꢁÞ
2+
NH )
3
(
H
3
N(CH
2
)
2
þ 2U12aba ꢁ b ꢁ cos g þ 2U13aca ꢁ c ꢁ cos b
þ 2U23bcb ꢁ c ꢁ cos aŠ:
vii
N(1)–C(1)
1.477(5)
C(1)–C(1)
1.492(8)
ꢀ
Bond angles ( )
Fe(1)O
6
octahedron
6
Fe(2)O octahedron
ethylenediammonium cation were geometrically placed.
The final R factors for all data were R ¼ 0:053
i
O(1) –Fe(1)–O(2)
i
ii
O(5) –Fe(2)–O(6)
ii
97.6(1)
82.4(1)
82.4(1)
97.6(1)
82.5(1)
97.5(1)
97.4(1)
82.6(1)
97.5(1)
82.6(1)
82.6(1)
97.4(1)
180.0(1)
180.0(1)
180.0(1)
90.4(1)
90.2(1)
90.0(1)
96.9(1)
93.3(1)
92.5(1)
97.6(1)
79.8(1)
92.5(1)
96.8(1)
79.7(1)
79.5(1)
172.0(1)
171.7(3)
172.7(1)
ii
O(1) –Fe(1)–O(2)
i
ii
O(5) –Fe(2)–O(4)
1
i
O(1) –Fe(1)–O(2)
ii
ii
O(6) –Fe(2)–O(4)
[
wR ¼ 0:092]. Maximum and minimum peaks in final
2
ii
O(1) –Fe(1)–O(2)
ii
i
ii
O(5) –Fe(2)–O(3)
i
À3
˚
difference synthesis were 1.179, À0.611 eA . The struc-
ture factor parameters have been deposited at the
Cambridge CrystallographicData Centre (CCDC
i
O(1) –Fe(1)–O(3)
i
i
O(4)–Fe(2)–O(3)
ii
O(1) –Fe(1)–O(3)
ii
O(6) –Fe(2)–O(1)
i
i
O(2) –Fe(1)–O(3)
i
i
O(4)–Fe(2)–O(1)
i
O(3) –Fe(2)–O(1)
ii
O(2) –Fe(1)–O(3)
i
i
2
22444). All drawings were made using the ATOMS
i
O(1) –Fe(1)–O(3)
ii
ii
O(5) –Fe(2)–O(2)
ii
ii
program [19]. Fractional atomic coordinates and equiva-
lent isotropicthermal parameters are shown in Table 2.
Selected bond distances and angles are given in Table 3.
ii
O(1) –Fe(1)–O(3)
ii
ii
O(6) –Fe(2)–O(2)
i
O(2) –Fe(1)–O(3)
ii
i
O(3) –Fe(2)–O(2)
ii
ii
O(2) –Fe(1)–O(3)
ii
i
O(1) –Fe(2)–O(2)
ii
i
O(1) –Fe(1)–O(1)
ii
ii
O(6) –Fe(2)–O(3)
i
i
i
O(2) –Fe(1)–O(2)
ii
ii
O(5) –Fe(2)–O(1)
2
.3. Physicochemical characterization techniques
i
O(3) –Fe(1)–O(3)
ii
ii
O(4)–Fe(2)–O(2)
The IR spectrum (KBr pellet) was obtained with a
Nicolet FT-IR 740 spectrophotometer in the 400–
HP(1)O
3
tetrahedron
v
3
HP(2)O tetrahedron
iv
O(2) –P(1)–O(3)
113.8(2)
114.2(2)
113.9(2)
102(2)
O(6)–P(2)–O(4)
vi
O(6)–P–O(5)
111.3(2)
110.7(2)
110.9(2)
107(2)
À1
4
000 cm
range. Diffuse reflectance spectrum was
iv
O(2) –P(1)–O(1)
v
O(3) –P(1)–O(1)
vi
registered at room temperature on a Cary 2415 spectro-
meter in the 210–2000 nm range. Mossbauer measure-
O(4)–P–O(5)
O(6)–P–H(22)
O(4)–P–H(22)
iv
O(2) –P(1)–H(11)
¨
v
O(3) –P(1)–H(11)
108(2)
104(2)
110(2)
107(2)
ments were recorded at room temperature in the
transmission geometry using a conventional constant-
vi
O(5) –P–H(22)
O(1)–P(1)–H(11)
5
7
acceleration spectrometer with a CoRh source. Mag-
neticmeasurements on a powdered sample were
performed in the temperature range 5.0–300 K, using a
Quantum Design MPMS-7 SQUID magnetometer. The
magneticfield was approximately 0.1 T, a value in the
range of linear dependence of magnetization vs.
magneticfield even at 5.0 K.
(
H
3
N(CH
2 3
)2NH )2+
vii
N(1)–C(1)–C(1)
110.4(4)
Symmetry codes: i ¼ Àx þ 1; Ày þ 1; Àz; ii ¼ x À 1; y; z; iii ¼
Àx; Ày þ 1; Àz; iv ¼ Àx þ 1; Ày þ 2; Àz; v ¼ x; y þ 1; z; vi ¼
x; y À 1; z; vii ¼ Àx þ 1; Ày þ 1; Àz þ 1:
2
À
½
Fe ðHPO Þ Š ; which are extended in the ab-plane.
3
3 4
3
. Results and discussion
The ethylenediammonium cations are located between
the layers, compensating their negative charge and
establishing hydrogen bonds with the anionicsheets
3
.1. Crystal structure of (C H N )[Fe (HPO )
3 4
2
10
2
3
(
Fig. 2). The sheets are constructed from iron(II) cations
The ðC H N Þ½Fe ðHPO Þ Š compound exhibits a
in an octahedral environment, giving rise to trimeric
entities with composition Fe O in which the octahedra
2
10
2
3
layered structure formed by anionic sheets of formula
3 4
3
12

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U.-C. Chung et al. / Journal of Solid State Chemistry 177 (2004) 2705–2713
2709
c
EnH
2
Inorganic
Layer
b
a
o
Fig. 2. Polyhedral view along the [110] direction of ðC H10N2Þ½Fe ðHPO Þ Š; showing the layered structure.
2
3
3 4
are sharing faces (Fig. 3). The phosphorus(III) ions from
2
O(5)
O(6)
O(4)
À
the (HPO3)
phosphite anions are four-coordinate,
P(2)
P(2)
with a vertex of the tetrahedron occupied by the
hydrogen atom and the others by the oxygen atoms
coordinated to the Fe(II) ions. The HPO tetrahedra
Fe(2)
O(3)
3
link the trimericunits, whi hc are extended in the ab-
plane. The existence of this layered architecture has been
P(1)
O(2)
O(1)
also found in the (C H
n
N ) [Mn (HPO ) ] (n ¼ 228)
2n+6
2
3
3 4
series
(
of
C H N )[Co (HPO ) ] phase [11c,d].
phosphite-compounds
and
in
the
P(1)
2
10
2
3
3 4
P(1)
In the Fe(1)O octahedra the Fe(1) ion is bonded to
6
Fe(1)
O(3)
i
the O(1) , O(1) , O(2) , O(2) and O(3) , O(3) oxygen
ii
i
ii
i
ii
atoms, belonging to the HP(1)O3 tetrahedra, with
˚
similar bond distances of 2.168(3) ( Â 2) A, 2.170(3)
O(2)
˚
˚
(
Fe(1)–O angles range from 82.4(1) to 97.5(1) . The
 2) A and 2.171(3) (  2) A, respectively. The cis-O–
ꢀ
ꢀ
Fe(2)
ꢀ
trans-O–Fe(1)–O angles are of 180 , due to the special
O(4)
position occupied by the Fe(1) ions. The distortion of
this polyhedron, from an octahedron (D ¼ 0) to a
trigonal prism (D ¼ 1), quantified by the Muetterties
and Guggenberger description [20], is D ¼ 0:11; which
O(5)
indicates a topology near to octahedral. In the Fe(2)O
Fig. 3. Polyhedral representation of the Fe
ðC H10N2Þ½Fe ðHPO Þ Š with detailed labeling of the atoms.
3
O12 cluster of
6
i
octahedra the Fe(2) ion is bonded to the O(1) , O(2)
ii
2
3
3 4
i
and O(3) oxygen atoms, belonging to the HP(1)O
3
˚
tetrahedron, with bond distances of 2.229(3) A,
tetrahedron, with bond lengths of 2.072(3), 2.066(3) and
˚
2.069(3) A, respectively. The longer metal-oxygen bond
distances correspond to the O(1), O(2) and O(3) oxygen
atoms, which are shared between the Fe(1)O6 and
˚
.242(3) A and 2.229(2) A, respectively. The six-fold
˚
2
coordination around the Fe(2) cation is completed with
ii
the O(4), O(5) and O(6) atoms from the HP(2)O3
ii

ARTICLE IN PRESS
U.-C. Chung et al. / Journal of Solid State Chemistry 177 (2004) 2705–2713
2710
Table 4
Fe(2)O6 octahedra. The cis-O–Fe(2)–O angles range
ꢀ
ꢀ
2 10 2 3 3 4
Unit-cell parameters of the (C H N )[M (HPO ) ] (M=Co, Fe and
from 79.5(1) to 97.6(1) . The trans-O–Fe(2)–O angles
ꢀ
Mn) compounds, and ionic radii of the metallic cations in hexacoor-
dination
deviate from the ideal value by approximately 8 . The
distortion of this polyhedron, from an octahedron
Compound
M=Co
M=Fe
M=Mn
(
D ¼ 0) to a trigonal prism (D ¼ 1), is D ¼ 0:02; which
also indicates a topology near to octahedral. The +2
oxidation state of the iron in the title compound was
verified as a sum of bond valences, ‘‘s’’, using the
formula: s ¼ exp½ðr À rÞ=BŠ; where r ðFe2OÞ ¼
˚
a (A
)
5.351(2)
5.347(4)
14.016(6)
80.98(5)
85.66(4)
60.04(4)
343.0(3)
0.745
5.416(1)
5.416(1)
13.977(2)
80.64(2)
85.25(1)
60.03(1)
350.5(1)
0.780
5.459(1)
5.460(2)
14.194(3)
80.65(2)
85.45(1)
60.04(2)
361.7(2)
0.830
˚
b (A)
˚
c (A)
a ( )
ꢀ
0
0
ꢀ
b ( )
˚
˚
1
:734 A, B ¼ 0:37 A and ‘‘r’’ is the observed bond length
ꢀ
g ( )
3
[
21]. The obtained oxidation states are 1.85 and 1.99v.u.,
V(A
Ionicradius
˚
)
for Fe(1) and Fe(2), respectively. These values are in good
agreement with those expected for this element in the
ðC H10N2Þ½Fe ðHPO Þ Š chemical formula and confirm
2
3
3 4
the results obtained by X-ray single-crystal structure
determination. The ðC H N Þ½Fe ðHPO Þ Š compound
2
10
2
3
3 4
exhibits values of the Fe(II)–O bond distances inter-
mediate between those observed for the isostructural
ðC H10N2Þ½M3ðHPO Þ Š M=Co and Mn phases in
2
3 4
accordance with the ionic radii of the Fe, Mn and Co
divalent cations [22]. Finally, the Fe–O–Fe angles in the
ꢀ
Fe O unit of ðC H10N2Þ½Fe ðHPO Þ Š are 82.84(9) ,
3
12
2
3
2.5(1) and 82.80(9) for Fe(1)–O(1)–Fe(2), Fe(1)–
3 4
ꢀ ꢀ
8
O(2)–Fe(2) and Fe(1)–O(3)–Fe(2), respectively, similar
to those found in the related manganese(II) and
cobalt(II) phases [11b,d]. The Fe(2)–Fe(1)–Fe(2) angle
ꢀ
is 180 as observed for all the isostructural phases
containing the M O (M=Fe, Mn and Co) trimeric
cluster.
3
12
The two HPO tetrahedra exhibit similar P–O bond
3
˚
distances, with a mean value of 1.525(4) A. The H(11)–
P(1) and H(22)–P(2) bond distances are equal in both
phosphite anions. The O–P–O angles are in the range
Fig. 4. Variation of the unit-cell volume vs. ionicradius for the
)[M (HPO ], M=Co, Fe and Mn, compounds.
(
C
2
H
10
N
2
3
3 4
)
ꢀ
ꢀ
from 110.7(2) to 113.9(2) , while the H–P–O angles
ꢀ
ꢀ
range from 102(2) to 110(2) . The ethylenediammo-
nium cation exhibits C–C and C–N bond distances in
the range usually found for this molecule [11b,11d–g,23]
and the angles are similar to those expected for sp3
hybridization. The ethylenediammonium cation is
bonded by hydrogen bonds to the oxygen atoms of the
ethylenediamine molecule [11b,11d–g,23,24] and the
2
À
(HPO3) phosphite oxoanion (see Table 5). The results
obtained are similar to those found for other related
phosphite phases containing the ethylenediammonium
cation as templating agent [11b–g].
2
À
HP(1)O3 anion linking the ½Fe ðHPO Þ Š inorganic
In the diffuse reflectance spectrum, two bands at
À1
3
3 4
˚
sheets, with O–H bond lengths in the 1.91(1)–1.95(1) A
range.
approximately 6860 and 9265 cm are observed, which
6
are characteristic of the iron(II) d high spin cation in a
slightly distorted octahedral environment. The bands
correspond to the electronic transitions from the
The ðC H10N2Þ½Fe ðHPO Þ Š phase has been shown
2
3
3 4
to be isostructural with the recently reported
5
5
T ( D) fundamental state to the excited level
(
C H N )[M (HPO ) ] (M=Mn and Co) phases (Table
3 4
2
10
2
3
2g
5
5
E ( D) [25,26] which is splitted as consequence of the
4
compared with those of the (C H N )[M (HPO ) ]
) [11b,d]. Refined parameters of the title compound are
2
g
Jahn–Teller effect expected for this cation. The energy
associated with this transition corresponds, according to
the Tanabe–Sugano diagram, to the Dq parameter. The
2
10
2
3
3 4
(M=Mn and Co) compounds in Table 4. Fig. 4 shows
the lineal evolution of the cell volume with the M
radius [22].
2
+
À1
value obtained is Dq ¼ 805 cm , in good agreement
with the values observed in other related compounds
2
+
3
.2. Infrared, UV-visible and M o¨ ssbauer spectroscopies
containing the Fe metallic ca tion [27].
The Mossbauer spectrum recorded in the paramag-
¨
The Infrared spectrum of ðC H N Þ½Fe ðHPO Þ Š
neticstate at 300 K is typi ca l of high-spin ferrous ions
(Fig. 5). The spectrum exhibits two symmetric doublets.
2
10
2
3
shows the characteristic bands of the protonated
3 4

ARTICLE IN PRESS
U.-C. Chung et al. / Journal of Solid State Chemistry 177 (2004) 2705–2713
2711
Table 5
À1
2 10 2 3 3 4
Selected IR bands (values in cm ) of (C H N )[Fe (HPO ) ]
Assignment
+
n(–NH
3
)
2890 (m)
2800 (m)
n(–CH
n(HP)
d(–NH
2
–)
2510, 2475 (m)
1590, 1620 (m,s)
1470 (w)
+
3
)
d(–CH
2
–)
)
nas(PO
d(HP)
3
1140, 1085 (s)
1070, 1045 (s)
990 (m)
ns(PO
ds(PO
das(PO
3
)
3
)
645, 620 (m)
490 (m)
3
)
Fig. 6. Thermal evolution of wm and w T curves of ðC H10N2Þ
m
2
½
Fe ðHPO Þ Š:
3
3 4
n=stretching, d=deformation, s=symmetric, as=asymmetric;
s=strong, m=medium, w=weak.
temperature to 5.0 K. The plot of the thermal evolution
of wm and w T is displayed in Fig. 6.
m
The molar magneticsus ce ptibility, wm; increases with
decreasing temperature, reaches a maximum at approxi-
mately 16.0 K, indicating that an antiferromagnetic
ordering is established at this temperature. After 16 K
the susceptibility decreases to 0.148 emu/mol at 5.0 K.
At high temperatures (T450 K) the wm vs. T curve
follows a Curie–Weiss law, with values of the Curie and
3
Curie–Weiss constants of Cm ¼ 10:734 cm K/mol and
Fig. 5. Mo
¨
ssbauer spectrum of ðC H10N2Þ½Fe ðHPO Þ Š at 300 K.
y ¼ À18:3 K, respectively. The effective magnetic mo-
ment and the g-value calculated from the Curie constant
2
3
3 4
are 5.3 m and 2.2, respectively. These values are in the
B
range habitually found for other iron(II) compounds
[29]. The value of the effective magnetic moment is
slightly higher than that of the spin only moment
Table 6
Isomer shift (IS) relative to a-Fe metal, quadrupole splitting (QS) and
¨
relative spectral areas (RSA) of the Fe Mossbauer spectrum of
57
(C
2
H
10
2
N )[Fe
3
(HPO
3
)
4
] at 300 K.
(
4.9 m ) due to the orbital contribution from the metallic
B
À1
À1
)
Site
IS (mm s
)
QS (mm s
RSA (%)
cation [29]. The w T vs. T product decreases from
m
10.085 emuK/mol at room temperature up to, approxi-
mately, 0.894 emuK/mol at 5.0 K. Both the continuous
Fe(1)
Fe(2)
1.2230(5)
1.2391(1)
2.942(1)
1.8606(2)
31.4(1)
68.6(1)
decrease of the w T vs. T curve and the negative Weiss
m
temperature indicate the existence of antiferromagnetic
interactions in this compound.
Taking into account the existence of the two crystal-
lographically independent iron(II) cations in ðC H10N2Þ
2
½
Fe ðHPO Þ Š; the spectrum was fitted by two doublets
4. Concluding remarks
3
3 4
of Lorentzians using the NORMOS program [28]. The
values obtained for the isomer shift and the quadrupole
splitting are characteristic of Fe(II) (Table 6). The
relative spectral areas are approximately in the 1:2 ratio
of the Fe(1) and Fe(2) cations, respectively. This result
confirms the existence of nonequivalent positions for the
iron(II) cations obtained from single crystal X-ray
structural refinement.
A new organically templated phase of formula
ðC H10N2Þ½Fe ðHPO Þ Š has been prepared in the form
2
3
3 4
of single crystals using mild hydrothermal conditions.
The phase exhibits a layered structure in which the
sheets are formed by Fe O trimericunits sharing fa ce s.
3
12
The IR spectroscopy has corroborated the existence of
the phosphite oxoanions and the ethylenediammonium
cations. The Dq parameter obtained by electronic
spectroscopy in the visible region is consistent
with iron(II) cations in octahedral coordination. The
3
.3. Magnetic properties
Magneticsu se cp tibility of
was measured on a powdered sample from room
ðC H N Þ½Fe ðHPO Þ Š
¨
Mossbauer spectrum shows the presence of two doublets
characteristic of the presence in the compound of two
2
10
2
3
3 4

ARTICLE IN PRESS
U.-C. Chung et al. / Journal of Solid State Chemistry 177 (2004) 2705–2713
2712
crystallographically independent iron(II) cations. The
magnetic measurements are consistent with the existence
of an antiferromagneticbehavior.
(d) V. Zima, K.-H. Lii, N. Nguyen, A. Ducouret, Chem. Mater.
0 (1998) 1914;
1
(
e) J. DeBord, W. Reiff, R. Haushalter, J. Zubieta, J. Solid State
Chem. 125 (1996) 186;
f) K.-H. Lii, Y.-F. Huang, J. Chem. Soc., Dalton Trans. (1997)
(
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221.
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D. Beltran, Eur. J. Solid State Inorg. Chem. 26 (1989)
03;
[
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a, P. Gomez, M.D. Marcos, P. Amoros, R. Ibanez,
Acknowledgments
6
This work was financially supported by the Ministerio
(
b) M.D. Marcos, P. Amoros, A. Beltran, R. Martinez, J.P.
Attfield, Chem. Mater. 5 (1993) 121;
de Educacio
dad del Paıs Vasco/EHU (9/UPV00169.310-13494/2001;
/UPV00130.310-13700/2001), which we gratefully ac-
knowledge. U-Chan Chung and Jon P. Chapman thanks
the Universidad del Paıs Vasco and the Ministerio de
Educacion y Ciencia (MAT2001), respectively, for
funding.
´
n y Ciencia (BQU2001-0678) and Universi-
´
(
c) M.P. Attfield, R.E. Morris, A.K. Cheetham, Acta Crystallogr.
C 50 (1994) 981;
9
(d) M.D. Marcos, P. Amoros, A. Le Bail, J. Solid State Chem.
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(
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