Isolated and edge-connected tetramers {(C2)2O 2Dy14} in the crystal structures of {(C2) 2O2Dy14}I24 and {(C 2)2O2Dyi}I18

Article abstract of DOI:10.1002/zaac.201000128

{(C₂)₂O₂Dy₁₄}I₂₄ (1) and {(C₂)₂O₂Dy₁₂}I₁₈ (2) were obtained by solid-state reactions in sealed tantalum containers at a temperature of 1000 °C. {(C₂)₂O₂Dy ₁₄}I₂₄ crystallizes in the space group P1 with a = 972.97(14) pm, b = 1033.03(13) pm, c = 1677.0(2) pm, α = 101.42(1)°, β = 92.72(1)°, γ = 112.75(1)° and V = 1509.3(3) ·10⁶ pm³, Z = 2, and is isotypic with the analogous yttrium and erbium cluster complexes. The tetrameric {(C₂) ₂O₂R₁₄}Ii cluster complexes consist of corner-sharing tetrahedra with endohedral oxygen atoms to which octahedra encapsulating C₂ dumbbells are attached on both sides. The tetramers are connected via iodide bridges yielding, e.g., {(C₂) ₂O₂Dy₁₄}I₂₄. Connection of the tetramers through common cluster edges leads to the one-dimensional polymeric cluster complex {(C₂)₂O₂Dy₁₂}I ₁₈. It crystallizes in the space group P6/m with a = 2024.18(8) pm, c = 1299.21(4) pm, V = 4610.1(3) × 10⁶ pm³ and Z = 8.

Full text of DOI:10.1002/zaac.201000128

ARTICLE
DOI: 10.1002/zaac.201000128
Isolated and Edge-Connected Tetramers {(C2)2O2Dy14} in the Crystal
Structures of {(C2)2O2Dy14}I24 and {(C2)2O2Dy12}I18
Kathrin Daub[a] and Gerd Meyer*[a]
Dedicated to Professor Bernd Harbrecht on the Occasion of His 60th Birthday
Keywords: Dysprosium; Cluster compounds; Structure elucidation; Lanthanides; Halides
Abstract. {(C2)2O2Dy14}I24 (1) and {(C2)2O2Dy12}I18 (2) were obtained corner-sharing tetrahedra with endohedral oxygen atoms to which octa-
by solid-state reactions in sealed tantalum containers at a temperature hedra encapsulating C2 dumbbells are attached on both sides. The tet-
¯
of 1000 °C. {(C2)2O2Dy14}I24 crystallizes in the space group P1 with ramers are connected via iodide bridges yielding, e.g., {(C2)2O2Dy14}I24.
a = 972.97(14) pm, b = 1033.03(13) pm, c = 1677.0(2) pm, α = Connection of the tetramers through common cluster edges leads to the
101.42(1)°, β = 92.72(1)°, γ = 112.75(1)° and V = 1509.3(3)·106 pm3, one-dimensional polymeric cluster complex {(C2)2O2Dy12}I18. It crystal-
Z = 2, and is isotypic with the analogous yttrium and erbium cluster lizes in the space group P6/m with a = 2024.18(8) pm, c = 1299.21(4)
complexes. The tetrameric {(C2)2O2R14}I32 cluster complexes consist of pm, V = 4610.1(3) × 106 pm3 and Z = 8.
{(C2)Dy4}I6 with chains of edge-connected octahedral clusters
Introduction
[8]. And there is just one bromide, {(C2)2Dy10}Br18 [9], iso-
In oxidation states of less than +3, there are two types of
lanthanide elements. One group behaves in oxidation state +2
as pseudo-alkaline-earth elements. The second group resem-
bles the early transition elements with their ability to metal-to-
metal bond as well as cluster formation [1]. The reason for this
behavior is the possibility of a configuration crossover, from
[Xe]4fn5d06s0 to [Xe]4fn–15d16s0. The “large” 5d orbitals may
delocalize or combine in covalent bonds or overlap with re-
spective orbitals of endohedral atoms in clusters (“lanthanides
as d metals”) [2].
As its homologue praseodymium, with the electronic config-
uration for Pr2+, 4f25d1/4f35d0, dysprosium is a borderline ele-
ment, with 4f95d1/4f105d0 for Dy2+. Experience shows that the
electronic configuration 4f25d1 is more important for Pr2+ and
4f105d0 for Dy2+. This knowledge is based, for example, on
the crystal structures and properties of PrI2 [3] and DyI2 [4].
Dysprosium(II) iodide crystallizes with the CdCl2-type of
structure with an electronic structure that accounts for an
4f105d0 configuration [5]. However, clusters have been men-
tioned, as for Dy7I12 [6] which may as well have been
{(C2)Dy6}I12Dy (for the nomenclature used here see ref. [1d]),
a compound, which has been obtained recently [7]. Three other
dysprosium cluster iodides have been reported, {(C2)2Dy10}I18
with dimeric cluster complexes as well as {(C2)3Dy12}I17 and
structural with the respective iodide just mentioned.
In our attempts to shed more light on the differences of the
chemistry of reduced halides of the neighboring elements dys-
prosium and holmium, we have also obtained two new iodides
whose important structural feature are tetrameric clusters,
{(C2)2O2Dy14} [7], on which we report here.
Results and Discussion
All cluster complex compounds of dysprosium hitherto re-
ported contain dicarbon units encapsulated in octahedral clus-
ters. The simplest example is {(C2)Dy6}I12Dy (see Figure 1),
which has 15 electrons for carbon–dysprosium bonding [7], a
rather comfortable number for isolated cluster complexes.
It was initially intended to synthesize dysprosium cluster
complexes with transition metals as endohedral atoms, at-
tempts, which have completely failed. One next step was to
secure cluster complexes with both carbon and transition metal
atoms as interstitials, iron in the present case. Such a reaction
yielded single crystals of {(C2)2O2Dy12}I18 (2). Even though
no oxygen source was used, as so often oxygen impurities,
which originate either from atmospheric impurities in the glove
box or from contaminated reactants or the reaction containers,
were ubiquitous. In further steps we then added Dy2O3 to the
reaction mixtures and obtained hetero-interstitial C2/O cluster
complexes in yields higher than 90 %. In order to keep the
reaction temperatures low and to grow crystals of better qual-
ity, we used sodium iodide (m.p. 662 °C) as a flux. However,
reaction temperatures around 1000 °C gave the best results.
{(C2)2O2Dy14}I24 (1) crystallizes with a structure that has
already been reported for the yttrium and erbium analogues
* Prof. Dr. G. Meyer
Fax: +49-221-470-5083
E-Mail: gerd.meyer@uni-koeln.de http://www.gerdmeyer.de
[a] Department für Chemie, Institut für Anorganische Chemie
Universität zu Köln
Greinstraße 6
50939 Köln, Germany
1716
© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2010, 636, 1716–1719

{(C2)2O2Dy14} Tetramers in {(C2)2O2Dy14}I24 and {(C2)2O2Dy12}I18
tetrahedra average to 366.7 pm and those in the octahedra to
382.1 pm, except for the edges parallel to the tetramer, which
are about 348 pm long.
The C2 dumbbell encapsulated in the octahedron has a C–C
bond length of 141.06(2) pm, a value in a range that is often
found for such compounds (see also ref. [10c]). The O–Dy
bond lengths are between 216.90(3) and 222.73(4) pm and
compare rather well with tetrahedra encapsulating an oxygen
atom as for example in {OLa4}Br7 (240 pm) or {OSm4}I6
(241 pm) [11].
The Dy–I distances all lie in a usual range from 295.44(6)
to 333.04(4) pm except for those who are neighboring the T–
T condensation; these are much larger with 369.95(5) and
373.07(6) pm, respectively. The {(C2)2O2Dy14}I32 tetramers
are connected through Ii and Ia bridges to each other, estab-
lished parallel to [100] and [001] according to the formulation
i–i
i–a
a–i
8/2
{(C2)Dy4Dy2/2}2{ODy4/2}2I16/1
I
8/2
I
(see Figure 3).
Figure 1. Part of the crystal structure of {(C2)Dy6}I12Dy exhibiting
the {(C2)Dy6}I18 cluster and the seventh dysprosium atom residing in
the third coordination sphere in an octahedron of iodide ions. The C2
dumbbells are disordered and arranged along the (pseudo-)fourfold
axes of the dysprosium octahedron.
Connections between the so established layers which are
stacked roughly in the [001] direction can only be of the van-
der-Waals type.
The crystal structure of {(C2)ODy6}I9 (2), or
{(C2)2O2Dy12}I18 for a better comparison with 1, features, in
principle,
the
same
tetrameric
building
blocks,
{(C2)2O2Dy12}I32. Two formula units of DyI3 need to be taken
out with respect to {(C2)2O2Dy14}I24 to connect the tetramers
through common octahedral edges to a polymeric chain, ac-
cording to (O–T–T–O–O–T–T–O)∞ (see Figure 4). An inspec-
tion of the Dy–Dy distances (see Table 1) shows that these are
pretty much the same with one obvious difference: the newly
established common edge of two octahedra has shortened con-
siderably, from 351.36(5) pm in 1 to 319.32(15) pm in 2.
Even the packing of the chains in {(C2)2O2Dy12}I18 looks
familiar when compared with {(C2)2O2Dy14}I24, it is in the
fashion of a hexagonal closest packing of rods, compare Fig-
ure 3 and Figure 5. One out of four chains is disordered. It has
only van-der-Waals contacts to its six neighboring chains and
the threefold axis seems to allow for three orientations parallel
[001]. It is situated in a tube of roughly 1300 pm diameter
which is created by the six surrounding chains that are con-
nected by i-a bridging. There are three equivalent orientations
for the chain enclosed in the tube, see Figure 5.
[10]. This is insofar not surprising as dysprosium, yttrium and
erbium have very similar sizes. It also shows that dysprosium
which forms a rather stable diiodide, DyI2, is capable of form-
ing clusters when the right endohedral atoms/atom groups are
available. The crystal structure consists of isolated tetramers
of the composition {(C2)2O2Dy14} which are composed of two
{C2Dy6} octahedra O and two {ODy4} tetrahedra T, all sharing
common edges in the sequence O–T–T–O (see Figure 2).
Conclusions
Two new dysprosium cluster complexes with O–T–T–O type
{(C2)2O2Dy14} cluster tetramers, where O stands for a
{(C2)Dy6} octahedron and T for a {ODy4} tetrahedron, were
obtained and structurally characterized for {(C2)2O2Dy14}I24
(isolated tetramers) and {(C2)2O2Dy12}I18 (chains of edge-con-
nected tetramers). This adds to a small number of dysprosium
Figure 2. {(C2)2O2Dy14}I32 tetramers in the crystal structure of
{(C2)2O2Dy14}I24 and their connection through common iodide
bridges.
The Dy–Dy bond lengths lie in the usual range with signifi- clusters, all of which encapsulate C2 dumbbells in octahedra
cantly shorter distances between dysprosium atoms building and, in the cases reported here, oxygen atoms in tetrahedra.
up the common edges (see Table 1). The bond length of the The ambivalent character of reduced dysprosium chemistry is
common octahedral/tetrahedral edge of 338.88(5) pm is only thereby clearly established. Dysprosium may be truly divalent
marginally shorter than the common edges between the tetra- as in DyI2 with a 4f105d0 configuration and also capable to
hedra, 339.75(4) pm. The outer Dy–Dy edge does obviously cluster formation that must involve the 4f95d1 configuration
relax with d = 351.36(5) pm. The other Dy–Dy edges of the for bonding with the endohedral atoms.
Z. Anorg. Allg. Chem. 2010, 1716–1719
© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1717

K. Daub, G. Meyer
ARTICLE
Table 1. Internuclear Dy–Dy distances in the {Dy14} cluster tetramer of {(C2)2O2Dy14}I24 (1) and {(C2)2O2Dy12}I18 (2).
1
d /pm
2
d /pm
common
edges
Dy1–Dy3
Dy5–Dy6
Dy7–Dy7
351.36(5)
338.88(5)
339.75(4)
Dy3–Dy3
Dy2–Dy3
Dy11–Dy11
319.32(15)
334.33(11)
336.43(18)
T
Dy5–Dy7
Dy5–Dy7
Dy6–Dy7
366.68(6)
368.55(7)
364.91(4)
Dy2–Dy11
Dy2–Dy11
370.55(8), 2×
372.01(8)
O
Dy2–Dy3
Dy2–Dy1
Dy2–Dy5
Dy2–Dy6
Dy4–Dy1
Dy4–Dy3
Dy4–Dy5
Dy4–Dy6
Dy3–Dy5
Dy1–Dy6
384.08(5)
376.83(5)
384.29(4)
377.44(6)
385.45(4)
376.08(6)
383.28(5)
389.38(5)
348.50(5)
347.63(5)
Dy1–Dy3
Dy1–Dy3
Dy1–Dy2
Dy1–Dy2
392.92(9), 2×
387.63(8), 2×
371.06(8), 2×
372.90(8), 2×
Dy2–Dy3
364.04(5), 2×
Figure 5. View down the infinite chains of edge-connected
{(C2)2O2Dy12}I32 tetramers in the crystal structure of {(C2)2O2Dy12}I18
exhibiting a packing in the fashion of the hexagonal closest packing
of rods.
Figure 3. Connection of the {(C2)2O2Dy14}I32 tetramers in the crystal
structure of {(C2)2O2Dy14}I24; view approximately down [001].
Experimental Section
Synthesis: DyI3 was synthesized from stoichiometric amounts of dys-
prosium (Chempur, Karlsruhe, Germany) and iodine (Acros, Geel, Bel-
gium), followed by sublimation in high vacuum for purification [12].
Due to air and moisture sensitivity of both reagents and products, all
handlings were carried out in an argon-filled glove box (M. Braun,
Garching, Germany).
{(C2)2O2Dy14}I24 (1): Compound 1 was obtained from the reaction of
DyI3 (200 mg), dysprosium powder (84 mg), Dy2O3 (7 mg, ≥ 99.9 %,
Chempur, Karlsruhe, Germany), graphite powder (11 mg, p.a. Merck,
Darmstadt, Germany), and NaI (approximately 1 g, p.a. Acros, Geel,
Belgium) as a flux. The reaction mixture was loaded in a tantalum
container which was He-arc sealed and heated at 1000 °C for ten days.
The product that was obtained after slow cooling consisted of black,
rectangular plates with edge lengths of ca. 0.2 mm, which were embed-
ded in the NaI flux.
Figure 4. Infinite chain of edge-connected {(C2)2O2Dy14}I32 tetramers
in the crystal structure of {(C2)2O2Dy12}I18.
{(C2)2O2Dy12}I18 (2): Compound 2 was first synthesized using DyI3
(150 mg), dysprosium powder (63 mg), graphite powder (8 mg), and
1718
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© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2010, 1716–1719

{(C2)2O2Dy14} Tetramers in {(C2)2O2Dy14}I24 and {(C2)2O2Dy12}I18
iron powder (10 mg, ≥ 99.9 % Merck, Darmstadt, Germany). The re- (Complex transition metal compounds with charge and orbital degrees
action mixture was loaded into a tantalum container, sealed and heated of freedom and disorder) as well as by the Fonds der Chemischen
at 1000 °C for 8 d. The product mixture mostly contained black nee- Industrie through a Doktorandenstipendium to K. D.
dles that easily split upon applying mechanical pressure.
Crystal Structure Determination: Single crystals of 1 and 2 were
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transmission (min., max.) = 0.0164, 0.0761; ρ(calc) = 6.158 g·cm–3;
62811 reflection intensities measured of which 3526 were symmetri-
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Acknowledgement
This work has been supported by the Deutsche Forschungsgemein-
schaft, Bonn, in the framework of the Sonderforschungsbereich 608
Received: March 13, 2010
Published Online: June 8, 2010
Z. Anorg. Allg. Chem. 2010, 1716–1719
© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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