A section through the compositional triangle Pr-Co-I at 600 °C: Pr 7CoI12 and Pr2Co2I

Article abstract of DOI:10.1002/zaac.200600152

At 600 °C, two phases exist in equilibrium in the system Pr-Co-I, Pr₇CoI₁₂ and Pr₂Co₂I, the former with isolated {Pr₆Co} clusters, the latter with Pr-Co-Pr slabs. The crystal structures were determined from single-crystal X-ray data: Pr ₇CoI₁₂: trigonal, R3 (no. 148), a = 1581.62(10), c = 1079.18(7) pm, Z = 3, R = 0.0493 for all data; Pr₂Co₂I: hexagonal, P6₃/mmc (no. 194), a = 403.86(4), c = 1743.4(2) pm, Z = 2. R = 0.1196 for all data.

Full text of DOI:10.1002/zaac.200600152

DOI: 10.1002/zaac.200600152
A Section Through the Compositional Triangle Pr-Co-I at 600 °C: Pr CoI
7
12
1)
and Pr Co I
2
2
Andriy Palasyuk, Ingo Pantenburg, and Gerd Meyer*
Köln, Institut für Anorganische Chemie der Universität
Received May 5th, 2006.
th
Dedicated to Professor Glen B. Deacon on the Occasion of his 70 Birthday
Abstract. At 600 °C, two phases exist in equilibrium in the system
PrϪCoϪI, Pr CoI12 and Pr Co I, the former with isolated {Pr Co}
clusters, the latter with PrϪCoϪPr slabs. The crystal structures
were determined from single-crystal X-ray data: Pr CoI12: trigonal,
0.0493 for all data; Pr
403.86(4), c ϭ 1743.4(2) pm, Z ϭ 2. R ϭ 0.1196 for all data.
2
Co
2
I: hexagonal, P6
3
/mmc (no. 194), a ϭ
7
2
2
6
7
¯
R3 (no. 148), a ϭ 1581.62(10), c ϭ 1079.18(7) pm, Z ϭ 3, R ϭ
Keywords: Praseodymium; Cobalt; Iodides; Crystal structure
The binary system praseodymiumϪiodine contains three com-
synthesized from the elements and purified by high-vacuum
pounds, PrI
2
, Pr
2
I
5
, and PrI
3
[1, 2]. With a third component Z
3
sublimation [14]. Mixtures of PrI , Pr and Co in molar ratios
added, and may be a fourth, usually an alkali metal A, a plethora
of ternary and quaternary compounds may be synthesized [3Ϫ5].
Most of these compounds contain an octahedral cluster centered
by an interstitial Z, {Pr
by twelve inner µ ligands, {Pr
appropriate to the respective position in the compositional triangle
of Figure 1 were filled under dry-box conditions (M. Braun,
Garching, argon atmosphere) into tantalum tubes, He-arc welded
and jacketed by silica ampoules. The samples were heated to
6
Z}. The clusters are principally surrounded
Z}Xi12, and they may be connected
Ϫ1
950 °C, kept there for 5 days, slowly cooled (5 °C·h ) to 600 °C,
2
6
with each other either by halide bridges and by cluster conden-
sation, mostly by common metal (praseodymium) edges.
annealed at this temperature for 10 days and quenched in ice water.
Annealing at 800 °C for 10 days and subsequent quenching did
not have much influence. No new compounds were detected. Single
crystals of Pr CoI12 and Pr Co I were selected with the aid of a
7 2 2
microscope in a dry-box and mounted in thin-walled glass capillar-
ies. For data collection procedures and crystal data see [15].
In the system PrϪCoϪI, there is a number of compounds possible,
due to knowledge about analogous systems, Pr
Pr CoI10 (not reported, but see Y RuI10 and Pr
Pr12Co 17 (not reported, but see Pr12Fe 17 [9]), Pr
10], see also Y16Ru 20 [11] and Gd20Mn 28 [12]), Pr
reported, but see Pr OsI [13]), and Pr Co I (not reported, but see
Pr Ni I or La Co I [13]), see Figure 1. The existence of these
7
CoI12 (P-XRD [6]),
CoBr10 [7, 8]),
CoI (P-XRD
CoI (not
6
6
6
2
I
2
I
4
5
[
4
I
4
I
3
3
3
3
2
2
Results and Discussion
2
2
2
2
phases is dependent upon temperature. While at low temperatures
kinetics might be a problem and long reaction times may be
needed, at high temperatures thermodynamics may prevent the
existence of other phases.
The ternary system PrϪCoϪI has been investigated occasionally,
see above. Most of the syntheses were carried out at temperatures
between 850 and 950 °C, followed by rapid cooling of the reaction
products. We have now performed an isothermal section at 600 °C
through the compositional triangle PrϪCoϪI system and have ob-
tained the most oxidized and the most reduced compounds,
Experimental Section
Pr{Pr
6 2 2
Co}I12 and Pr Co I, respectively, in this system, but none of
The metals (Pr, Co) as well as iodine were purchased and used as
the compositions possible in between (Fig. 1).
3
such without further purification. PrI as a starting material was
Pr
structure type with a crystal structure that was first determined
for Sc NCl12 and Sc CI12 [16, 17]. Meanwhile, a large number of
7 6
CoI12 ؍ Pr{Pr Co}I12 crystallizes with a rather well-explored
7
7
*
Prof. Dr. G. Meyer
isostructural compounds were discovered and characterized mostly
by powder X-ray diffraction [3]. We have added recently
Institut für Anorganische Chemie
Universität zu Köln
Greinstraße 6
D-50939 Köln
E-Mail: gerd.meyer@uni-koeln.de
www.gerdmeyer.de
Pr{Pr
6
Fe}I12 (single-crystal data [18]). Lattice constants from pow-
CoI12
der X-ray diffraction (P-XRD) had been established for Pr
7
as a ϭ 1581.5(1), c ϭ 1080.5(1) pm [6] and are in good agreement
with the present single crystal data, a ϭ 1581.62(10), c ϭ
1079.18(7) pm and with the lattice constants of the neighbouring
1
)
Paper presented at the XVIIIth Tage der Seltenen Erden (Terrae
Pr FeI , a ϭ 1582.96(10), c ϭ 1078.33(6) pm [18]. According to
7
12
Pr(1){Pr(2)
6
Co}I(1)i
6
I(2)
iϪa
6
,
Pr
7
CoI12
contains “isolated”
Rarae 2005) at Bonn-Röttgen/Germany, November 30th Ϫ Decem-
ber 2nd, 2005 (www.terrae-rarae.de).
{Pr(2) Co} clusters edge-capped by twelve iodide ligands with
6
Z. Anorg. Allg. Chem. 2006, 632, 1969Ϫ1971
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1969

A. Palasyuk, I. Pantenburg, G. Meyer
Fig. 1 The compositional triangle PrϪCoϪI at 600 °C with the two phases, Pr
temperature together with important features of their crystal structures. Other possible compositions, Pr
Pr CoI , although not observed at 600 °C, are also exhibited.
7
CoI12 and Pr
2
Co
2
I, which exist in equilibrium at that
6
CoI10, Pr12Co 17, Pr CoI , and
2
I
4
5
3
3
Pr(1) filling empty octahedral holes of iodide ions. Both Pr-Pr
391.96(7) and 392.35(8) pm] and Pr-Co distances [277.29(5) pm]
within the {Pr(2) Co} cluster are in good agreement with those of
similar compounds, as are the Pr-I distances.
[2] For an overview of the literature see: G. Meyer, A. Palasyuk,
Inorg. Chem. in Focus (G. Meyer, D. Naumann, L. Wesemann,
editors), Wiley-VCH, Weinheim, volume 3, chapter 4, 2006.
[3] A. Simon, H. J. Mattausch, G. J. Miller, W. Bauhofer, R. K.
Kremer, Handbook on the Physics and Chemistry of Rare
Earths (K. A. Gschneidner, Jr., L. Eyring, eds.), Elsevier Sci-
ence Publ., Amsterdam, volume 15, chapter 100, 1991, 191.
[
6
Pr
Gd
pounds of which Pr
and La Co I, for example, from powder X-ray diffraction data [13].
2
Co
2
I crystallizes with a structure that was first established for
I [19] and later on found for a number of isostructural com-
Ni I was investigated from single-crystal data
2
Fe
2
2
2
[
4] J. D. Corbett, J. Chem. Soc., Dalton Trans. 1996, 575; J. D.
Corbett, Inorg. Chem. 2000, 39, 5178; J. D. Corbett, J. Alloys
Compd. 2006, in press.
2
2
The crystal structure can be understood as an AA stacking of
praseodymium atoms with all trigonal-prismatic voids in between
occupied by cobalt atoms with Pr-Pr distances of 403.86(4) pm in
the layers and 375.5(4) pm between the layers and Co-Co distances
of only 233.25(3) pm and Pr-Co distances of 297.6(4) pm. These
[
5] G. Meyer, M. S. Wickleder, Handbook on the Physics and Chem-
istry of Rare Earths (K. A. Gschneidner, Jr., L. Eyring, eds.),
Elsevier Science Publ., Amsterdam, volume 28, chapter 177,
2000, 53.
Pr
layers with Pr-I distances of 340.4(2) pm. In the isotypic nickel
compound, Pr Ni I, the interlayer Pr-Pr distances are longer for
the nickel compound (which corresponds with the lattice constants,
Pr Co I, a ϭ 403.86(4), c ϭ 1743.4(2) pm, and Pr Ni I, a ϭ
08.3(2), c ϭ 1721.1(6) pm) wheras the intralayer Pr-Pr distances
2 2
Co intermetallic slabs are sheathed above and below by iodine
[
[
[
[
[
6] T. Hughbanks, J. D. Corbett, Inorg. Chem. 1988, 27, 2022.
7] T. Hughbanks, J. D. Corbett, Inorg. Chem. 1989, 28, 631.
8] R. Llusar, J. D. Corbett, Inorg. Chem. 1994, 33, 849.
9] Y. Park, J. D. Corbett, Inorg. Chem. 1994, 33, 1705.
10] M. W. Payne, P. K. Dorhout, J. D. Corbett, Inorg. Chem. 1991,
2
2
2
2
2
2
4
3
0, 1467.
11] M. W. Payne, M. Ebihara, J. D. Corbett, Angew. Chem. 1991,
03, 842; Angew. Chem. Int. Ed. Engl. 1991, 30, 856.
12] M. Ebihara, J. D. Martin, J. D. Corbett, Inorg. Chem. 1994,
3, 2079.
13] Y. Park, J. D. Martin, J. D. Corbett, J. Solid State Chem. 1997,
29, 277.
14] G. Meyer, Synthesis of Lanthanide and Actinide Compounds,
G. Meyer & L. R. Morss, editors), Kluwer Academic Pub-
lishers, Dordrecht, The Netherlands, 1991, 135.
are shorter for the nickel compound, resulting in a shorter Pr-Ni
distance of 296.5(2) pm as compared with Pr-Co of 297.6(5) pm,
suggesting slightly stronger Pr-Ni bonding.
[
[
[
[
1
3
Acknowledgements. This work was generously supported by the
Deutsche Forschungsgemeinschaft, Bonn (Schwerpunktprogramm
1
„Lanthanoidspezifische Funktionalitäten“) and by the State of
Nordrhein-Westfalen and the Universität zu Köln.
(
Ϫ1
[
15] Pr
7
I12Co, 2568.10 g mol
; diffractometer IPDS-I, Stoe,
Darmstadt; Mo-K
α
(graphite monochromator,
λ
ϭ
[
1] J. D. Corbett, L. F. Druding, W. J. Burkhard, C. B. Lindahl,
71.073 pm); T ϭ 293(2) K; 2θ range ϭ 3.8Ϫ56.3°; 250 images,
0° Յ ϕ Յ 250°; ∆ϕ ϭ 1°; indices: Ϫ20 Յ h Յ 20, Ϫ20 Յ k Յ
Disc. Faraday Soc. 1961, 32, 79.
1970
www.zaac.wiley-vch.de
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2006, 1969Ϫ1971

7 2 2
Pr CoI12 and Pr Co I
2
0, Ϫ14 Յ l Յ 14; 9501 reflection intensities measured of
SHELXS-97 and SHELXL-97, Programs for the Solution and
Refinement of Crystal Structures, Göttingen, 1997). Numerical
absorption corrections were applied after optimisation of the
crystal shapes (X-RED and X-SHAPE (X-SHAPE 1.01, Crys-
tal Optimization for Absorption Correction, STOE & Cie
GmbH, Darmstadt, 1996; X-RED 1.22, Stoe Data
Reduction Program (C), Stoe & Cie GmbH, Darmstadt,
2001). Further details on the crystal structure determination
may be obtained from the Fachinformationszentrum
Karlsruhe, 76344 Eggenstein-Leopoldshafen, Germany (fax:
(ϩ49)7247-808-666; e-mail: crysdata@fizkarlsruhe.de), on
which 1254 were symmetrically independent, Rint ϭ 0.1043,
F(000) ϭ 3228, µ ϭ 23.106 mm . Trigonal, R3 (no. 148), a ϭ
Ϫ1
¯
6
3
1581.62(10), c ϭ 1079.18(7) pm, V ϭ 2337.9(3) 10 pm , Z ϭ
3. R values: R /wR for 1099 reflections with I >2σ(I ):
0.0446/0.1170 and for all data: 0.0493/0.1194; Goodness of fit
1
2
0
0
(
all data) 1.063.
Pr Co
I, 526.58 g molϪ1; diffractometer IPDS-I, Stoe, Darm-
stadt; Mo-K (graphite monochromator, λ ϭ 71.073 pm); T ϭ
93(2) K; 2θ range ϭ 3.8Ϫ56.3°; 200 images, 0° Յ ϕ Յ 200°;
2
2
α
2
∆
ϕ ϭ 1°; indices: Ϫ5 Յ h Յ 5, Ϫ5 Յ k Յ 5, Ϫ22 Յ l Յ 21;
2088 reflection intensities measured of which 146 were sym-
quoting the depository number ICSD-416274 (Pr
7
CoI12
)
metrically independent, Rint ϭ 0.3142, F(000) ϭ 450, µ ϭ
and ICSD-416273 (Pr
tation.
[16] S.-J. Hwu, J. D. Corbett, J. Solid State Chem. 1986, 64, 331.
2 2
Co I), the authors and the journal ci-
Ϫ1
3
2.121 mm . Hexagonal, P6
c ϭ 1743.4(2) pm, V ϭ 2462.6(5) 10 pm , Z ϭ 2. R values:
/wR for 129 reflections with I >2σ(I ): 0.0787/0.2291
and for all data: 0.1196/0.2987; Goodness of fit (all data)
.385.
3
/mmc (no. 194), a ϭ 403.86(4),
6
3
R
1
2
0
0
[17] D. S. Dudis, J. D. Corbett, S.-J. Hwu, Inorg. Chem. 1986, 25,
3434.
1
[18] A. Palasyuk, I. Pantenburg, G. Meyer, Acta Crystallogr. 2006,
E62, i61.
[19] M. Ruck, A. Simon, Z. Anorg. Allg. Chem. 1993, 619, 327.
Structure solutions and refinements were carried out using the
programs SHELXS-97 and SHELXL-97 (G.M. Sheldrick,
Z. Anorg. Allg. Chem. 2006, 1969Ϫ1971
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1971