Two 3-aminobenzoates of praseodymium, Pr(OOC-Ph-NH2)3(H2O) and Pr(OOC-Ph-NH2)(OOC-Ph-NH)

Article abstract of DOI:10.1016/j.jallcom.2007.04.230

In the monohydrate Pr(OOC-Ph-NH₂)₃(H₂O) (1), Pr³⁺ is nine-coordinate with only oxygen atoms coordinating. Two carboxylate groups are bidentate-bridging, four are tridentate-bridging and there is one coordinating

Full text of DOI:10.1016/j.jallcom.2007.04.230

Journal of Alloys and Compounds 451 (2008) 429–432
Two 3-aminobenzoates of praseodymium, Pr(OOC-Ph-NH2)3(H2O)
and Pr(OOC-Ph-NH2)(OOC-Ph-NH)
Holger Flemig, Ingo Pantenburg, Gerd Meyer∗
Institut fu¨r Anorganische Chemie, Universita¨t zu Ko¨ln, Greinstrasse 6, D-50939 Ko¨ln, Germany
Available online 22 April 2007
Abstract
In the monohydrate Pr(OOC-Ph-NH2)3(H2O) (1), Pr3+ is nine-coordinate with only oxygen atoms coordinating. Two carboxylate groups are
bidentate-bridging, four are tridentate-bridging and there is one coordinating water molecule, hence the coordination number is nine. The chains
run along [0 1 0]. In the anhydrous Pr(OOC-Ph-NH2)(OOC-Ph-NH) (2), the central Pr3+ ion is surrounded by six oxygen atoms and two nitrogen
atoms in a distorted square antiprism. These polyhedra are connected to each other via two opposite O–O edges to form chains running parallel
[0 0 1]. The chains, in which all carboxylate groups are tridentate-bridging, are arranged in a centered rectangular fashion and are further connected
via OOC-Ph-NH bridging.
© 2007 Elsevier B.V. All rights reserved.
Keywords: Praseodymium; 3-Amino-benzoate; Crystal structures
1. Introduction
2. Results and discussion
Carboxylates and among them rare-earth carboxylates are an
important and widespread class of compounds, see for a recent
review [1]. In connection with our involvement with rare-earth
coordination compounds in general [2], we have recently under-
taken a rather systematic study on ␣,␻-dicarboxylates, among
them glutarates, adipinates and pimelinates [3–5]. In an attempt
to obtain bimetallic complexes with both hard and soft cations,
for example Pr3+ and Hg2+ or Tl+, with a bifunctional ligand
such as 3-amino-benzoic acid, we have now obtained two new
praseodymium 3-amino-benzoates, Pr(OOC-Ph-NH2)3(H2O)
(1) and the surprising Pr(OOC-Ph-NH2)(OOC-Ph-NH)
(2).
Pr(OOC-Ph-NH2)3(H2O) (1), and the isotypic Nd(OOC-Ph-
NH2)3(H2O) as well, crystallize with an orthorhombic structure
in which all Pr3+ are crystallographically equivalent and are
nine-coordinate with only oxygen atoms coordinating, Fig. 1a.
Of these, one oxygen atom originates from the water molecule of
the monohydrate. Six carboxylate groups are directly attached
to Pr3+, two are bidentate and four monodentate. The mean
Pr3+–O2− distance in 1 for coordination number 9 (CN 9) is
3+
2−
˚
2.535 A (see Table 1) is in excellent accord with Pr –O
˚
distances in similar carboxylates, for example 2.464 A (CN
˚
8) in Pr(OBz)3(HOBz) (HOBz = benzoic acid) [7], 2.518 A
˚
(CN 9) in Pr(OAc)3(H2O)1.5 [8] and 2.564 A (CN 10) in
There are a number of rare-earth 3-amino-benzoate-
trihydrates, [M(OOC-Ph-NH2)3(H2O)3H2O)3 known, M = La–
Lu, Y [6] which have monomeric structures with three biden-
tate carboxylic ligands and three coordinating water molecules
constituting a tricapped trigonal prism of oxygen atoms around
M3+.
[Pr(OAc)3(HOAc)](HOAc) [9]. As the formula Pr(OOC-Ph-
NH2)3(H2O) suggests, all carboxylate groups in 1 are shared
according to Pr(OOC-Ph-NH2)6/2(H2O)1/1 with like neighbour-
ing coordination polyhedra, two of which are bidentate-bridging
and four are tridentate-bridging, Fig. 1b. The chains run along
[0 1 0], b is the “short” needle axis, and are packed in a way
which is exhibited in Fig. 1c. There might be some additional
stabilization through aromatic interaction (“␲–␲ stacking”) [10]
with phenyl groups, in the [1 0 0] direction, parallel but offset
˚
stacked although 3.81 A apart.
∗
Pr(OOC-Ph-NH2)(OOC-Ph-NH) (2) is, as far as we know,
Corresponding author. Tel.: +49 221 470 3262; fax: +49 221 470 5083.
the first anhydrous rare-earth 3-amino-benzoate, and a rather
E-mail address: gerd.meyer@uni-koeln.de (G. Meyer).
0925-8388/$ – see front matter © 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jallcom.2007.04.230

430
H. Flemig et al. / Journal of Alloys and Compounds 451 (2008) 429–432
Fig. 1. (a) Details of the crystal structure of Pr(OOC-Ph-NH2)3(H2O) (1) in the neighbourhood of Pr(III). Symmetry-related atoms are drawn as empty ellipsoids.
(b) Part of the chains running along [0 1 0]. (c) Crystal structure viewed down the b-axis and, as a detail, the offset stacked phenyl groups of 3-amino-benzoic acid.
The black, white, dark gray and medium gray circles symbolize Pr, C, O and N atoms.
3+
With an average of 2.755 A, see Table 1, the Pr –O2− distances
unusual one. Under the solvothermal (ethanol) conditions with
Pr6O11 and TlNO3 present, one of the two 3-amino-benzoic
acids per formula unit is deprotonated not only at the carboxylic
group but also at the amino group. As we have no indication for a
lower symmetry than that of centrosymmetric space group C2/c,
all amino groups are equal and, hence, we must assume that the
–NH2 and –NH groups are statistically distributed. Again, in 2
all Pr3+ ions are equal and are surrounded by six oxygen atoms
and two nitrogen atoms as a distorted square antiprism, Fig. 2a.
˚
are much longer than in 1. There are two additional Pr3+–N3−
distances at 2.807 A. The PrO6N2 polyhedra are connected to
each other via two opposite O–O edges to chains running parallel
[0 0 1], Fig. 2b. The chains, in which all carboxylate groups
are tridentate-bridging, are arranged in a centered rectangular
fashion and are, further, connected via OOC-Ph-NH bridging,
Fig. 2c. Phenyl rings are again parallel but offset stacked and the
˚
˚
distance between them is 3.63 A, shorter than in 1.
Table 1
3. Experimental details
˚
Selected interatomic distances (A) for Pr(OOC-Ph-NH2)3(H2O) and Pr(OOC-
Ph-NH2)(OOC-Ph-NH)
For the synthesis of Pr(OOC-Ph-NH2)3(H2O) (1), a metathesis reac-
tion of barium 3-amino-benzoate and praseodymium sulfate, molar ratio 3:1,
in dry pentanol was carried out in a steel autoclave with Teflon inlay at
180 ◦C for 48 h and cooled to ambient temperature during 120 h. Barium
3-amino-benzoate was obtained before from a neutralisation reaction of 3-
amino-benzoic acid and barium hydroxide in water. Praseodymium sulfate
precipitates from an aqueous solution of praseodymium trichloride with sodium
sulfate. In both cases, the precipitates were dried under vacuum for several
days.
Pr(OOC-Ph-NH2)3(H2O)
Pr(OOC-Ph-NH2)(OOC-Ph-NH)
Pr1–O311
Pr1–O211
Pr1–O111
Pr1–O212
Pr1–O312
Pr1–O112
Pr1–O1
2.417(3)
2.448(3)
2.459(3)
2.485(4)
2.506(3)
2.536(3)
2.543(3)
2.601(3)
2.816(3)
Pr1–O11
Pr1–O12
Pr1–O11ꢀ
Pr1–N41
2.602(15) 2×
2.784(5) 2×
2.878(11) 2×
2.962(16) 2×
Pr1–O211ꢀ
Pr1–O112ꢀ
Pr(OOC-Ph-NH2)(OOC-Ph-NH) (2) was obtained from the reaction of
0.15 g Pr6O11, 0.15 g TlNO3 and 0.3 g 3-amino-benzoic acid in 12 ml ethanol in
a steel autoclave with Teflon inlay at 140 ◦C for 72 h. Within one day the reac-

H. Flemig et al. / Journal of Alloys and Compounds 451 (2008) 429–432
431
Fig. 2. (a) Details of the crystal structure of Pr(OOC-Ph-NH2)(OOC-Ph-NH) (2) in the neighbourhood of Pr(III). Symmetry-related atoms are drawn as empty
ellipsoids. (b) Part of the chains running along [0 0 1]. (c) Crystal structure of Pr(OOC-Ph-NH2)(OOC-Ph-NH) viewed down the c-axis and, as a detail, the offset
stacked phenyl groups of 3-amino-benzoic acid. The black, white, dark gray and medium gray circles symbolize Pr, C, O and N atoms.
tion mixture was cooled to 120 ◦C, held there for 24 h and cooled to ambient
temperature within 48 h.
Suitable single crystals of both compounds, red-brown (1) and dark-
red (2), were selected under a polarizing microscope and mounted in glass
capillaries. Scattering intensities were collected by an imaging plate diffrac-
tometer (IPDSI/IPDSII, STOE & CIE) equipped with a normal focus, 1.75 kW,
crystal-shape optimization were applied for all data [12]. The programs used
were Stoe’s X-Area [13], including X-RED and X-Shape for data reduction
and numerical absorption correction [14], and the WinGX suite of programs
[15], including SIR-92 [16] and SHELXL-97 [17] for structure solution and
refinement.
All C–H and N–H atoms were placed in idealized positions and con-
strained to ride on their parent atom. The H-atoms of the water molecule were
located in difference Fourier maps and refined, with O–H distances restrained to
˚
sealed tube X-ray source (Mo K␣, λ = 0.71073 A) operating at 50 kV and
35 mA.
˚
Intensity data for Pr(OOC-Ph-NH2)3(H2O) (1) were collected at 293 K in
138 frames with ␻-scans (0 ≤ ω ≤ 180◦; ψ = 0◦, 0 ≤ ω ≤ 96◦; ψ = 90◦, ꢀω = 2◦,
exposure time 5 min) in the 2θ range of 1.9 to 54.8◦. For the isotypic Nd(OOC-
Ph-NH2)3(H2O) see [11]. Intensity data for Pr(OOC-Ph-NH2)(OOC-Ph-NH)
(2) were collected at 293 K by ψ-scans in 100 frames (0 ≤ ψ ≤ 200◦, ꢀψ = 2◦,
exposure time 5 min) in the 2θ range of 3.8–56.3◦. The data were corrected
for Lorentz and polarization effects. Numerical absorption corrections based on
0.82(2) A. The last cycles of refinement included atomic positions for all atoms,
anisotropic thermal parameters for all non-hydrogen atoms and isotropic ther-
mal parameters for all hydrogen atoms. Details of the refinements are given in
Table 2.
Crystallographic data have been deposited with the Cambridge Crystal-
lographic Data Centre as supplementary publication nos. CCDC 297928 for
Pr(OOC-Ph-NH2)3(H2O), CCDC 297927 for Pr(OOC-Ph-NH2)(OOC-Ph-NH)

432
H. Flemig et al. / Journal of Alloys and Compounds 451 (2008) 429–432
Table 2
Crystal data and structure refinements of Pr(OOC-Ph-NH2)3(H2O) and Pr(OOC-Ph-NH2)(OOC-Ph-NH)
Empirical formula
Formula weight (g mol−1
C
21H20N3O7Pr
C14H11N2O4Pr
412.16
)
567.31
Crystal system, space group
Orthorhombic, Pbca
a = 15.934(2)
b = 7.962(1)
c = 33.086(3)
Monoclinic, C2/c
a = 10.225(2)
b = 15.904(2)
c = 8.562(1)
β = 100.92(2)
1367.3(4)
◦
˚
Unit cell dimensions (A/ )
3
˚
Volume (A )
4197.5(7)
Z, calculated density (g/cm3)
Absorption coefficient (mm−1
Crystal color and habitus
Crystal size (mm3)
8, 1.795
2.371
4, 2.002
3.580
)
Red, needle-like
0.4 × 0.1 × 0.1
1.9–54.8
−20 ≤ h ≤ 20
−9 ≤ k ≤ 10
−37 ≤ l ≤ 42
36921/2856
0.0936
Red, plate-like
0.2 × 0.2 × 0.05
3.8–56.3
−13 ≤ h ≤ 13
−20 ≤ k ≤ 20
−10 ≤ l ≤ 10
6381/1322
0.0589
Theta range for data collection (◦)
Limiting indices
Reflections collected/unique
R(int)
Absorption correction
Max./min. transmission
Data/restraints/parameters
Goodness-of-fit on F2
R indicesa [I > 2σ(I)]
wR2 = 0.0607
Numerical
0.7716/0.5781
4621/2/300
0.834
R(F) = 0.0313
wR2 = 0.1003
0.0006(1)
Numerical
0.6786/0.4511
1528/0/99
1.148
R(F) = 0.0382
Extinction coefficient
Largest difference peak/hole (e A
0.009(1)
1.15 (0.42 A from C6)
−3
˚
˚
˚
)
0.97 (1.39 A from Pr1)
˚
˚
−0.85 (0.81 A from Pr1)
−1.42 (0.85 A from Pr1)
1/2
R1 = Σ ||Fo| − |Fc||/Σ |Fo|, wR2 = [Σw(|Fo|2 − |Fc| ) /Σw(|Fo| ) ]1/2, S2 = [Σw(|Fo| − |Fc| ) /(n − p)] , with w = 1/[σ2(|Fo| ) + (0, 0346 P) ] for
2
2
2
2
2
a
2
2
2
2
2
Pr(OOC-Ph-NH2)3(H2O) and w = 1/[σ2(|Fo| ) + (0, 0792 · P) ] for Pr(OOC-Ph-NH2)(OOC-Ph-NH), were P = (|Fo| + 2|Fc| )/3. Fc* = k Fc [1 + 0,001 · |Fc|
2
2
2
2
λ3/sin(2θ)]−1/4
.
and CCDC 297935 for Nd(OOC-Ph-NH2)3(H2O). Copies of the data can be
obtained, free of charge, on application to CHGC, 12 Union Road, Cambridge
CB2 1EZ, UK (fax: +44 1223 336033 or e-mail: deposit@ccdc.cam.ac.uk).
[7] S. Gomez Torres, G. Meyer, J. Alloys Compd. 451 (2008) 433.
[8] A. Lossin, G. Meyer, Z. Naturforsch. 47b (1992) 1602.
[9] S. Gomez Torres, G. Meyer, Z. Kristallogr. Suppl. 24 (2006)
155.
[10] C.A. Hunter, K.R. Lawson, J. Perkins, C.J. Urch, J. Chem. Soc. Perkin
Trans. 2 (2001) 651.
Acknowledgments
[11] Nd(OOC-Ph-NH2)3(H2O):
C21H20N3O7Nd
(570.64 g.mol−1);
This work was generously supported by the Deutsche
Forschungsgemeinschaft, Bonn (Graduiertenkolleg “Azen-
trische Kristalle”), by the State of Nordrhein-Westfalen and the
diffractometer IPDS-I, Stoe, Darmstadt; Mo K␣ (graphite monochro-
mator, λ = 0.71073 A); T = 293(2) K; θmax = 28.14◦; 100 images,
˚
0◦ ≤ ϕ ≤ 200◦; ꢀϕ = 2◦; indices: −21 ≤ h ≤ 21, −9 ≤ k ≤ 9, −43 ≤ l ≤ 43;
ρcalc = 1.798 g cm−3; 23231 reflection intensities measured of which
2686 were symmetrically independent, Rint = 0.1045, F(000) = 2264,
μ = 2.512 mm−1. Orthorhombic, Pbca (no. 61), a = 15.937(2), b = 7.970(1),
¨
¨
Universitat zu Koln.
References
˚
˚
c = 33.194(6) A, V = 4216.5(10) A3, Z = 8.
R values: R1/wR2 for
4779 reflections with [I0 > 2σ(I0)]: 0.0457/0.0972 and for all data:
0.1027/0.1151; Sall = 0.896.
[1] C.N.R. Rao, S. Natarajan, R. Vaidhyanathan, Angew. Chem. Int. Ed. 43
(2004) 1466.
[2] G. Meyer, J. Alloys Compd. 300–301 (2000) 113.
[3] C. Bromant, W. Nika, I. Pantenburg, G. Meyer, Z. Anorg. Allg. Chem. 631
(2005) 2416.
[4] C. Bromant, H. Flemig, W. Nika, I. Pantenburg, G. Meyer, Z. Anorg. Allg.
Chem. 632 (2006) 151.
[5] H. Flemig, I. Pantenburg, G. Meyer, Z. Anorg. Allg. Chem. 632 (2006)
2205.
[12] STOE & Cie GmbH, X-Shape 1.06, Crystal Optimisation for Numerical
Absorption Correction (C), Darmstadt, Germany, 1999.
[13] Stoe & Cie GmbH, X-Area V. 1.16, Darmstadt, Germany, 2003.
[14] Stoe & Cie GmbH, X-RED V. 1.22, Stoe Data Reduction Program (C)
Darmstadt, Germany, 2001.
[15] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.
[16] A. Altomare, G. Cascarano, C. Giacovazzo, J. Appl. Crystallogr. 26 (1993)
343.
[6] A.E. Koziol, B. Klimek, K. Stepniak, Z. Rzaczynska, W. Brzyska, O.I.
Bodak, L.G. Akselrud, V.V. Pavlyuk, V.A. Tafeenko, Z. Kristallogr. 200
(1992) 25.
[17] G.M. Sheldrick, SHELXL-97; Programs for Crystal Structure Analysis,
University of Go¨ttingen, Germany, 1997.