Insights into metal framework constructions from the syntheses of new scandium- and yttrium-rich telluride compounds: Y5Ni2Te2 and Sc6PdTe2 [19]

Full text of DOI:10.1021/ja002875j

10740
J. Am. Chem. Soc. 2000, 122, 10740-10741
Insights into Metal Framework Constructions from
the Syntheses of New Scandium- and Yttrium-Rich
Telluride Compounds: Y5Ni2Te2 and Sc6PdTe2
Paul A. Maggard and John D. Corbett*
Department of Chemistry
Iowa State UniVersity
Ames, Iowa 50011
ReceiVed August 3, 2000
Remarkable structural relationships are evident in the conden-
sation of rare-earth-metal (R) chains in Gd
in Y Ni Te and to chains in Sc Ni Te as well as for the reaction
of Pd with pairs of metal chains in Sc Te to give heterometal
rumpled sheets in Sc PdTe . The different pathways appear to
be governed principally by the relative strengths of R-R vs R-M
heterometal interactions.
3 3
MnI to metal sheets
5
2
2
5
2
2
2
6
2
5 2 2
Figure 1. A section of the infinite heterometal sheets in Y M Te (M )
Fe, Co, Ni) (99.9% probability ellipsoids). Y-Y distances in Å are for
the Fe analogue. Dark atoms are Te; shaded, M; open, Y.
The nature of stable metal frameworks has been investigated
1
since early works of Zintl, Pauling, and others. Examples of low-
dimensional metal-metal-bonded solids number in the hundreds,
yet an ongoing problem is the interconnection of these within a
coherent chemical and structural framework. The large field of
related ternary compounds that contain a late transition metal
interstitial affords wider views of structural principles,2 and here
we report even broader structural interrelationships among new
chalcogenide systems.
-4
The new metal-rich compounds reported here were synthesized
5
via typical high-temperature solid-state chemical reactions and
7
characterized by single-crystal X-ray diffraction methods. The
5 2 2
section of the Y M Te (M ) Fe, Co or Ni) structure shown in
Figure 1 for Fe contains heterometal layers that are infinite in
projection and along Bb . The Y atoms alternate by a/2 in depth
and generate body-centered cubes of Y and puckered 6-rings that
sandwich two types of M atoms (shaded). Both M atoms center
trigonal prisms of yttrium (vertical in Figure 1) that generate
zigzag chains of M atoms, spaced at 2.30 Å for Fe, through
sharing of rectangular faces. The intermetallic layers are separated
by tellurium atoms. Extended H u¨ ckel band calculations indicate
that the overlap population (OP) for the shortest Y-Y interlayer
interaction (3.78 Å) is only 25-30% the values for intralayer
Figure 2. Condensation of the single 1D chains in Gd
sheets in Y Ni Te and (II) infinite double chains in Sc Ni
atoms are Sc, Y, or Gd; shaded, Ni or Mn; black, Te or I. All are
projections along the short axis of infinite chains or sheets. The process
3
MnI
3
into (I)
6
bonds (∼0.23), an effect seen before in similar structures. The
5
2
2
5
2
Te . Unfilled
2
total bonding about Fe can be described in terms of OP values of
0
.29 for each Fe-Fe bond together with OP values (on a different
9
in both can be viewed as 2R
3 3 5 2 2
MI f R M Te + RTe after substitution
scale) of 0.24-0.29 each for six Fe-Y contacts.
of one Te for each two I (R ) rare-earth element).
A major point of this work is shown in Figure 2, the broad
10
structural interrelationships between Gd
3
MnI
3
5 2 2
(top), Y Ni Te
(
lower left), and Sc Ni (lower right). The parent Gd MnI
5
2
Te 6
2
3 3
(
1) (a) Zintl, E. Angew. Chem. 1939, 52, 1. (b) Pauling, L. Phys. ReV. 1938,
structure contains isolated metal chains identical in construction
to those making up Y Ni Te and Sc Ni Te , infinite zigzag chains
of late 3d metals bonded within trigonal prisms of the group 3
metal. Until now the relationship of the Gd MnI structure to
anything else has been nil, but the conceptual conversions both
follow the process:
5
4, 899. (c) Pearson, W. B. The Crystal Chemistry and Physics of Metals
5
2
2
5
2
2
and Alloys; Wiley-Interscience: New York, 1972. (d) Nesper, R. Angew.
Chem., Int. Ed. Engl. 1991, 30, 789.
(
(
(
(
2) Wang, C.; Hughbanks, T. Inorg. Chem. 1996, 35, 6987.
3) Kleinke, H.; Franzen, H. F. J. Alloy Compd. 1996, 238, 68.
4) Kleinke, H. J. Alloy Compd. 1998, 270, 136.
3
3
5) Y (Fe,Co,Ni) Te were synthesized from pressed pellets of Y Te ,
5
2
2
2
3
6
yttrium, and Fe, Co, or Ni. The synthetic techniques involve the use of welded
tantalum tubes as containers that were heated to 1050 °C for 84 h. Guinier
powder patterns revealed 75-95% yields, with small amounts of YTe as a
2 R MI f R M Te + RTe
3
3
5
2
2
side product. Sc
6
PdTe
2
was synthesized from a similar pellet at 1050 °C for
(R ) Gd, Y or Sc; M ) Mn or Fe, Co, Ni)
7
2 h, which gave ∼85% yields plus small amounts of ScTe.
(
6) Maggard, P. A.; Corbett, J. D. Inorg. Chem. 1999, 38, 1945.
wherein replacement of 2I- by Te2- is followed by condensa-
tion and the loss of RTe. The condensation of the 1-D chains in
(
7) Single-crystal data were collected on Rigaku AFC6R and Bruker CCD
diffractometers to 2θmax e 56°, from which Cmcm (No. 63) and Pnma (No.
6
2) space groups were indicated, respectively. Absorption effects were
Gd
to give the Y
yield the Sc Ni
MnI
takes place either through sharing of (I) trans vertices
Ni Te layer structure, or (II) adjacent vertices to
Te arrangement. The first results in polymeri-
3
3
8
corrected by two ψ-scans and by SADABS, respectively. Direct methods
5
2
2
and Fourier mapping were used to locate all atomic positions, and anisotropic
2
5
2
2
refinements converged at R(F)/R ) 4.6/4.2% and R1/wR2(F ) ) 2.8/7.3%,
w
respectively. The parameters and distances for each are in the Supporting
Information.
zation of the rods into sheets, while the second halts at the dimer
stage. The type I condensation results in four additional Y-Y
contacts per chain repeat, while type II yields two more Sc-Sc
and two Sc-Ni interactions per repeat. Qualitatively, the choice
(
8) Blessing, R. H. Acta Crystallogr. 1995, A51, 33.
(
5 2 2
9) A more detailed structural and electronic analysis of the Y M Te phases
and a report on a hydride derivative of the Ni phase will be forthcoming.
1
0.1021/ja002875j CCC: $19.00 © 2000 American Chemical Society
Published on Web 10/13/2000

Communications to the Editor
J. Am. Chem. Soc., Vol. 122, No. 43, 2000 10741
Figure 3. Generation of Sc
6
PdTe
2
(right) from Sc
2
Te
3
(left) by substitution of Pd for one type of Te. Sc - blue, Te - red, Pd - yellow.
appears to originate with energetic differences expected for the
gain of early-early vs early-late transition metal bonding;
framework metals from the early 4d and 5d periods are known
to form stronger homoatomic bonds than do the corresponding
2
Palladium substitutes in a portion of the Sc Te structure where
Sc-Sc bond populations are low relative to the distances,
replacing Sc-Te matrix effects and polar bonding with more
covalent Sc-Pd bonds as the energy matching of the interacting
orbitals became better and additional valence orbitals on Pd are
added. Nonetheless, an appreciable difference in Sc 3d - Pd 4d
orbital energies remains, so that the bonding does not disrupt the
3
d metals.11 In other words, stronger R-R interactions favor I,
while stronger R-M interactions favor II, where stronger and
weaker are inferred from bond population analyses. The new (Gd,-
5 2 2 5 2 2
Dy) Ni Te analogues of Y Ni Te are also consistent with this
6 2
Sc network as it does in Sc NiTe (below). A secondary effect
trend.1 It should be obvious that theoretical treatments of the
electronic changes represented in Figure 2 are a good deal more
difficult than this geometric approach.
2,13
of the stronger Sc1-Pd interactions is that the proportions of the
condensed double octahedra have switched roles. The seeming
chemical equivalency of Pd and Te in this chemistry has some
Another unexpected structural interrelationship was revealed
analogues in other system as well, namely that the 3d metal and
on attempts to substitute Pd for Ni in Sc
led instead to Sc PdTe , the first example of heterometal-induced
condensation or polymerization of metal chains, blades, etc., here
5 2 2
Ni Te , Figure 3. This
3
the nonmetal in Hf
5
Co1+x
P
3-x are mixed within trigonal prismatic
6
2
2
6
sites of Hf and likewise in Zr sites in Zr Fe0.6Se2.4. These effects
1
4
may be more size- than orbital-dependent; all of these substrates
are metallic so that the electron count changes are not so
important. The general loss of R-R metal bonding with gains to
in Sc
2
Te via
4
Sc Te + Pd f Sc PdTe + 2ScTe
2
6
2
M neighbors is also found in the contrasting R
6 2
MTe (R ) Sc,
Dy; M ) Mn, Fe, Co, Ni)15 which crystallize in an ordered Fe
P
2
2
The reactant Sc Te shown in projection on the left contains both
type with clearly stronger R-M d orbital interactions in centered
trigonal prisms of R. More detailed structural and electronic
analyses are forthcoming in full papers, the emphasis here being
the insightful structural relationships that assist our understanding
of the formation and stability of metal frameworks.
large complex and simple zigzag chains of scandium atoms (blue).
The larger unit comprises quasi-infinite chains of pairs of distorted
trans-edge-sharing metal octahedra, further condensed on opposite
edges with trans-edge-sharing square pyramids. The new
Sc
and basic atom distribution except that d palladium atoms
yellow) have replaced the circled telluride that separated the two
6 2
PdTe , Figure 3 right, has the same space group, unit cell,
10
(
Acknowledgment. This work was supported by the National Science
Foundation, Solid State Chemistry, via Grant DM-9809850 and was
carried out in the facilities of the Ames Laboratory, U.S. Department of
Energy.
chains, stitching the Sc “blades” and the zigzag chains into
rumpled bimetallic sheets. The Sc-Pd distances to the vertices
of a distorted trigonal prism of Sc (normal to the page) vary over
2
.78-2.83 Å and to the Sc atoms that formally cap the rectangular
faces, 2.91-3.33 Å, close to those about that point in Sc
Internal Sc-Sc distance trends remain similar to those in Sc
2
Te.
Te.
Supporting Information Available: Tables of crystallographic and
2
atomic parameters and nearest neighbor distances in Y
5 2 2
Fe Te and
(
10) Ebihara, M. Martin, J. D.; Corbett, J. D. Inorg. Chem. 1994, 33, 2078.
11) Franzen, H. F.; K o¨ ckerling, M. Prog. Solid State Chem. 1995, 23,
Sc PdTe (PDF). This material is available free of charge via the Internet
at http://pubs.acs.org.
6
2
(
2
65.
(
12) Herle, P. S.; Corbett, J. D., to be submitted for publication.
13) Comparable interpretations of heterometal bonding effects in terms
(
JA002875J
of the degree of energy matching have been advanced for interstitial-centered
cluster halides of the rare-earth metals: K o¨ ckerling, M.; Martin, J. D., Inorg.
Chem., accepted.
(
14) Maggard, P. A.; Corbett, J. D. Angew. Chem. Int. Ed. Engl. 1997, 18,
(15) Maggard, P. A.; Corbett, J. D. Inorg. Chem. 2000, 39, 4143; Bestaoui,
N.; Herle, P. S.; Corbett, J. D. J. Solid State Chem. 2000, in press.
1
1974.