Hydrothermal synthesis, crystal structure and magnetism of [Nd(C7H6NO2) 3·H2O]n, a novel coordination polymer with three-dimensional network

Article abstract of DOI:10.1016/S0022-2860(01)00938-3

A novel coordination polymer with three-dimensional network, [Nd(C₇H₆NO₂) ₃·H₂O]_n, has been hydrothermally synthesized and characterized by X-ray diffraction of the single-crystal, IR and U

Full text of DOI:10.1016/S0022-2860(01)00938-3

Journal of Molecular Structure 608 (2002) 95±99
www.elsevier.com/locate/molstruc
Hydrothermal synthesis, crystal structure and magnetism
of [Nd(C7H6NO2)3´H2O]n, a novel coordination polymer with
three-dimensional network
a,
b
S.Y. Niu , G.D. Yang , Y.L. Zhang , J. Jin , L. Ye , Z.Z. Yang
a
a
b
a
*
aDepartment of Chemistry, Liaoning Normal University, Dalian 116029, People's Republic of China
bKey Labof Suparmolecular Structure and Spectroscopy, Jilin University, Changchun 130023, People's Republic of China
Received 15 August 2001; revised 31 October 2001; accepted 31 October 2001
Abstract
A novel coordination polymer with three-dimensional network, [Nd(C7H6NO2)3´H2O]n, has been hydrothermally synthesized
and characterized by X-ray diffraction of the single-crystal, IR and UV±vis±NIR spectra as well as by the measurement of the
ꢀ
magnetic susceptibility. The polymer crystallizes in the monoclinic, space group P2(1)/n with a ˆ 9:8069ꢀ5† A; b ˆ
ꢀ
ꢀ
ꢀ3
22:736ꢀ2† A; c ˆ 9:8254ꢀ8† A; b ˆ 100:053ꢀ5†8; V ˆ 2157:1ꢀ3† A ; Z ˆ 4; and RꢀRw† ˆ 0:038ꢀ0:0924†: Cryomagnetic inves-
tigations (4.5±300 K) reveal that the polymer possesses weak antiferromagnetic property. q 2002 Elsevier Science B.V. All
rights reserved.
Keywords: Nd(III) coordination polymer; Three-dimensional network; Hydrothermal synthesis; Crystal structure; Magnetism
1. Introduction
and polymers with Ln(III) ions. Therefore, these
complexes have great potential of applications to optics,
electronics, magnetics, biology as well as medicine, etc.
[6±10]. Although the study of mononuclear and bi-
nuclear complexes as well as polymers is very exten-
sive, the report for Ln(III) coordination polymer having
three-dimensional network is rarely seen [11±17].
This paper reports a novel Nd(III) coordination
polymer having three-dimensional network structure
and varied H-bonds with p-aminobenzoate ligands.
We study the hydrothermal synthesis, structural char-
acterization and magnetism of the polymer.
In recent years, the study of metal-coordination
polymerhasdrawnmoreandmoreattention.Especially,
the investigation on spontaneous self-assembly of
metal-coordination provides a solid foundation for
exploring the relationship between the structural frame-
work and function and for researching the interactions
between the metals and metals of the polymer [1±5].
We have an interest in the self-assembling of lantha-
nide coordination ions. The coordinating capacity of
lanthanide elements is powerful and the coordination
number is larger. Especially the con®guration of their
4f electrons possesses speci®c properties of spectrum
and magnetism. All of these provide particular struc-
tures and functions for the coordination compounds
2. Experimental
2.1. Physical measurements
* Corresponding author. Fax: 186-411-4214450.
E-mail address: zyang@mail.dlptt.ln.cn (S.Y. Niu).
The element contents were measured using a
0022-2860/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-2860(01)00938-3

96
S.Y. Niu et al. / Journal of Molecular Structure 608 (2002) 95±99
Fig. 1. The structure diagram of [Nd(C7H6NO2)3´H2O] unit.
PE-240C elemental analyzer and TLASMA-II ICP.
The IR spectrum was recorded on a NICOLET
NEXUS 470 FT/IR spectrometer (CsI pellet) and
UV±vis±NIR spectrum (diffuse re¯ectance spectrum)
was obtained on a UV-3100 spectrophotometer by
using BaSO4 pellet as a reference. The magnetic
susceptibilities were measured with a MPMS-7 super-
conducting quantum magnetometer in the temperature
range of 4.5±300 K and in the magnetic ®eld of 1 T.
(ns coo); 395(s) (nNd±O); 290(m) (nNd±N). The UV±vis±
NIR spectrum (diffuse re¯ectance, BaSO4 pellets as
reference, nm) has 11 bands: 870, 802, 748, 740, 638,
630, 584, 526, 515, 470, 365, which correspond to the
4
4
transitions of Nd(III) ion, respectively: I9=2 ! FJ
4
4
(J ˆ 3/2, 5/2, 7/2, 9/2), S3/2, GJ (J ˆ 5/2, 7/2, 9/2,
4
11/2) and DJ (J ˆ 1/2, 3/2) [20].
2.3. X-ray crystallography
Crystal data: C21H20N3O7Nd, M ˆ 570:625ꢀ3†;
2.2. Synthesis
ꢀ
monoclinic, space group P2(1)/n a ˆ 9:8069ꢀ5† A;
ꢀ
ꢀ
The polymer was prepared by hydrothermal
reaction. Nd(NO3)3´6H2O (0.44 g, 1.0 mmol) and
NH2C6H4COOH (0.68 g, 5.0 mmol) was dissolved in
water (30 ml, 50 8C), after addition of ethanol (5 ml),
the solution was heated and stirred. The dissolution
was over, and the liquid was sealed in a 50 ml te¯on-
lined autoclave and heated at 125 8C for 96 h. Then
the autoclave was cooled to room temperature. Flesh-
colored crystals were observed after several days. The
product was collected by ®ltration. Anal. found (%):
C, 43.56; H, 3.45; N, 7.31; Nd, 25.63; calcd for
C21H20N3O7Nd: C, 44.21; H, 3.53; N, 7.36; Nd,
25.28. The IR spectrum (CsI pellet, cm21): 3397(m),
b ˆ 22:736ꢀ2† A; c ˆ 9:8254ꢀ8† A; b ˆ 100:053ꢀ5†8;
ꢀ3
ꢀ
V ˆ 2157:1ꢀ3† A ; Z ˆ 4; l ˆ 0:71073 A; T ˆ
293 K: A single-crystal with dimensions 0.24 £
0.32 £ 0.38 mm3 was ®xed inside a glass capillary.
Data were collected on a Siemens R3 four-circle
diffractometer with the v-scan mode in the range of
3.5 , 2u , 488. A total of 4286 (3386 independent)
re¯ections were measured. The structure was solved by
heavy atom method and re®ned with a full-matrix least-
squares program. All the re¯ection data were corrected
for the L±P factor and empirical absorption. In re®ne-
ment, the function minimized was W(F0 2 Fc)2,
P
where
weighing
scheme
W21 ˆ ‰s2ꢀF0†2 1
3312(m) (nN±H); 3280(m) (nO±H´ ´ ´O); 3125(m) (nC±H,
Ar); 1608 (vs) (nCyC, Ar); 1510 (vs) (nas coo); 1392 (vs)
ꢀ0:0570P†2 1 3:0949PŠ; ꢀP ˆ ꢀF021 2Fc2†=3† was
used. Final R ˆ 0:038; Rw ˆ 0:092‰I . 2sꢀI†Š;

S.Y. Niu et al. / Journal of Molecular Structure 608 (2002) 95±99
97
graphic Data Center. The deposition number is
CCDC 168176.
3. Results and discussion
3.1. Structure
The structural analysis shows that the polymer is
prepared by self-assembly of [Nd(C7H6NO2)3´H2O]
units. Each unit contains one Nd(III) ion and three
independent p-aminobenzoate ligands. One (A) of
three ligands coordinates to one Nd(III) ion with
two carboxyl O atoms, while other two ligands (B,
C) bond, respectively, to two Nd(III) ions and one
(C) of them links to third Nd(III) ion with its amino
N atom. Each Nd(III) ion is coordinated by six
carboxyl O atoms, one amino N atom and one O
atom of structure water molecule, forming eight-coor-
dination irregular polyhedron. The distances of Nd±O
Ê
range from 2.386 to 2.595 A and Nd±N bond length is
Ê
2.713 A (Fig. 1). In the polymer, the Nd(III) ions are
bridged ®rst by two carboxyl groups from two respec-
tive p-aminobenzoates, forming one-dimensional
chain which is along the direction of the c axis. In
Ê
the interchain, the Nd±Nd separation is 5.243 A.
Then the Nd(III) ions belonging to adjacent chains
Fig. 2. Crystal packing diagram of [Nd(C7H6NO2)3´H2O] in the two-
dimensional network.
ꢀ3
S ˆ 1:013;
D=s ˆ 0:001;
ꢀ3
Drmax ˆ 1:175 eA ;
Drmin ˆ 21:058 eA : The atomic coordinates of
hydrogen atoms were found in the Fourier ®gure.
All calculations were performed on a VMS computer
by using shelxtl programs. Further details of the
crystallographic data and the crystal structure investi-
gations can be obtained from Cambridge Crystallo-
Fig. 3. Crystal packing diagram of [Nd(C7H6NO2)3´H2O] in the three-dimensional network.

98
S.Y. Niu et al. / Journal of Molecular Structure 608 (2002) 95±99
Table 1
Table 2
Atomic coordinates ( £ 104) and equivalent isotropic displacement
Ê
The selected bond lengths (A) and angles (8) (A: 2x 1 1, 2y 1 1,
2z 1 1; B: 2x 1 1, 2y 1 1, 2z 1 2)
3
Ê 2
parameters (A £ 10 ) for the polymer. U(eq) is de®ned as one third
of the trace of the orthogonalized Uij tensor
Bond lengths
Nd±O(22)
Nd±O(32)
Nd±O(31)
Nd±O(21)
Nd±O(11)
Nd±O(12)
Nd±Ow
2.386(5)
2.398(5)
2.406(5)
2.409(5)
2.487(5)
2.523(5)
2.595(5)
2.713(7)
Atoms
x
y
z
U(eq)
Nd
5172(1)
1628(8)
8947(8)
7186(7)
3358(5)
4856(5)
3938(6)
6263(6)
3445(5)
6998(5)
5490(5)
3858(8)
3248(8)
1961(9)
1444(9)
2216(8)
4995(1)
1611(3)
2058(3)
5737(3)
4324(2)
3914(2)
5858(2)
4574(2)
4896(2)
4723(2)
5876(2)
3870(3)
3276(3)
3216(3)
2674(4)
2168(3)
2224(4)
2772(4)
4140(3)
3613(3)
3096(3)
2587(4)
2578(3)
3096(4)
3600(4)
4839(3)
5335(3)
5141(3)
5282(4)
5619(3)
5815(3)
5667(3)
7372(1)
5215(8)
7411(8)
6855(7)
6151(5)
7810(5)
6414(5)
5613(5)
8821(5)
9220(5)
9076(5)
6817(7)
6405(7)
5633(9)
5237(8)
5628(8)
19(1)
38(2)
54(2)
26(2)
27(1)
27(1)
39(1)
36(1)
27(1)
26(1)
27(1)
24(2)
25(2)
35(2)
35(2)
30(2)
41(2)
34(2)
27(2)
27(2)
30(2)
40(2)
35(2)
36(2)
34(2)
20(2)
23(2)
27(2)
32(2)
20(2)
26(2)
26(2)
N(1)
N(2)
N(3)
O(11)
O(12)
O(21)
O(22)
O(31)
O(32)
Ow
Nd±N(3)
Bond angle
O(22)±Nd±O(32)
O(22)±Nd±O(31)
O(32)±Nd±O(31)
O(22)±Nd±O(21)
O(32)±Nd±O(21)
O(31)±Nd±O(21)
O(22)±Nd±O(11)
O(32)±Nd±O(11)
O(31)±Nd±O(11)
O(21)±Nd±O(11)
O(22)±Nd±O(12)
O(32)±Nd±O(12)
O(31)±Nd±O(12)
O(21)±Nd±O(12)
O(11)±Nd±O(12)
O(22)±Nd±Ow
O(32)±Nd±Ow
O(31)±Nd±Ow
O(21)±Nd±Ow
O(11)±Nd±Ow
O(12)±Nd±Ow
O(22)±Nd±N(3)
O(32)±Nd±N(3)
O(31)±Nd±N(3)
O(21)±Nd±N(3)
O(11)±Nd±N(3)
O(12)±Nd±N(3)
Ow±Nd±N(3)
94.3(2)
147.3(2)
92.1(2)
107.6(2)
139.8(2)
87.1(2)
77.2(2)
125.7(2)
73.1(2)
92.5(2)
79.4(2)
73.6(2)
71.8(2)
142.3(2)
52.1(2)
139.3(2)
73.8(2)
73.0(2)
67.6(2)
141.3(2)
130.28(4)
71.4(2)
80.2(2)
141.2(2)
75.7(2)
140.7(2)
138.9(2)
68.3(2)
118.9(5)
94.1(4)
92.8(4)
116.5(5)
150.2(5)
146.2(4)
137.2(4)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(30)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
3510(10)
4031(9)
6470(7)
7195(8)
7240(8)
7812(10)
8388(8)
8387(9)
7784(9)
7352(7)
11,241(7)
10,752(8)
9437(8)
8571(7)
9072(8)
10,377(8)
6412(10)
6788(9)
4874(8)
5517(7)
4747(8)
5365(10)
6761(8)
7517(8)
6903(8)
10,498(7)
8801(7)
7450(7)
6821(8)
7454(7)
8790(8)
9446(8)
Ê
various hydrogen bonds, N±H¼O (2.930 A) and N±
Ê
H¼Ow (2.846 A)) assembling three-dimensional
C(34)±N(3)±Nd
C(10)±O(11)±Nd
C(10)±O(12)±Nd
C(20A)±O(21)±Nd
C(20)±O(22)±Nd
C(30B)±O(31)±Nd
C(30)±O(32)±Nd
network structure (Fig. 3). The selected bond lengths
and angles, non-hydrogen atomic coordinates and
thermal parameters are listed in Tables 1 and 2,
respectively.
Obviously, there are two characters in the structure of
the polymer: (1) It has two kinds of direct coordinate
atoms (N and O) from the ±NH2 and ±COO2 group of
the same ligand. This Ln(III) coordination polymer is
seldom seen. (2) The structure of the polymer
possesses three-dimensional in®nite network, which
is favorable for electron and proton transfer between
metal atoms or metals and ligands [18].
are linked by the ±COO2 or ±NH2 group from
different ligands forming two-dimensional in®nite
network in the ac plane with center height about b/
Ê
2. The distance of Nd±Nd in the intrachain is 4.164 A
(Fig. 2). The two-dimensional network is bonded by

S.Y. Niu et al. / Journal of Molecular Structure 608 (2002) 95±99
99
Fig. 4. Temperature dependence of (a) xm, (b) meff and (c) xm21
.
[3] X.S. Tan, Z.S. Ma, N.C. Shi, D.G. Fu, J. Chen, W.X. Tang, J.
Chem. Soc. Dalton Trans. (1996) 2735.
3.2. Magnetic properties
[4] S. Ferlay, T. Mallah, J. Vaissermann, F. Bartolome, P. Veillet,
M. Verdaguer, Chem. Commun. (1996) 2481.
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Fun, K. Chinnakali, I.A. Razak, J. Chem. Soc. Dalton Trans.
(1999) 2311.
In light of variable temperature magnetic moments
in 4.5±300 K, we obtained the molar magnetic
susceptibility (xm) and effective magnetic moments
(meff) and studied the curves of xm±T, meff±T and
xm21±T (Fig. 4(a)±(c)). In Fig. 4(a), as the temperature
(T) downs to 11 K, xm shows an obvious increase,
which reveals a tendency of the magnetic coupling
of Nd(III)±Nd(III) in the polymer. From Fig. 4(b) it
can be seen that as T decreases, meff decreases and
drops quickly at 11 K, which demonstrates that there
is an antiferromagnetic coupling between the Nd(III)
ions. Furthermore, if we treat xm21±T curve (Fig. 4(c))
as linear and extrapolate it intersecting the T axis, the
crossing is at the side of 2T, which agrees with the
xm ˆ C=ꢀT 1 u† [19]. These phenomena shows that
this polymer possesses the character of weak anti-
ferromagnetic material.
[6] L. Ma, O.R. Evans, B.M. Foxman, Inorg. Chem. 38 (1999)
5837.
[7] K. Aparna, S.S. Krishnamurthy, M. Nethaji, P. Balaram, Poly-
hedron 16 (1997) 507.
[8] D.M.L. Goodgame, S.P.W. Hill, D.J. Williams, Inorg. Chim.
Acta 272 (1998) 131.
[9] S. Aime, F. Benetollo, G. Bombieri, S. Colla, M. Fasano, S.
Paoletti, Inorg. Chim. Acta 254 (1997) 63.
[10] S.Y. Niu, Z.Z. Yang, Q.C. Yang, B. Yang, J.Q. Chao, G.D.
Yang, E.Z. Shen, Polyhedron 16 (1997) 1629.
[11] P.R. Wei, D.D. Wu, Z.Y. Zhou, T.C.W. Mak, Polyhedron 17
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Acknowledgement
[15] S. Romero, J.C. Tromble, Polyhedron 18 (1999) 1653.
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Angew. Chem. Int. Ed. Engl. 39 (2000) 3644.
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3367.
This research was supported by the National
Science Foundation of China (No. 20071016).
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