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