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Contributions to the Chemistry of the Binary Compounds of the Transition Elements.

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Contributions to the Chemistry of the Binary Compounds of the Transition
Elements
BY PROF. DR. HAAKON HARALDSEN
CHEMICAL INSTITUTE A, UNIVERSITY OF OSLO, BLINDERN (NORWAY)
Dedicated to Professor W. KIenim on the occasion of his 70th birthday
Phase and structural relationships of the sulfur, selenium, and tellurium compounds of the
4d and Sd transition elements of groups I V to VII of the periodic system are discussed.
Homologous elements behave very similarly with respect to the chalcogens, and this
is particularly the case for niobium and tantalum, and for molybdenum and tungsten.
However, zirconium, niobium, and molybdenum have a greater tendency towards
formation of chalcogen-poor phases than their homologues hafnium, tantalum, and
tungsten. Subchalcogenides are known only for zirconium and niobium. The number
of phases and the tendency towards formation of solid solutions are considerably
smaller among the tellurides than among the sulfides and selenides. The crystal
structures of the telluride phases also differ from those of the sulfide and selenide phases of
analogous composition. In addition, a review of the phase and structural relationships of
the arsenic and antimony compounds of the 4d and 5d transition elements of groups V
to VII is given.
I. Introduction
Previous investigations on the compounds of the transition elements with the chalcogens sulfur, selenium, and
tellurium have shown that these substances show a very
complex and, in many respects, unique behavior. Most
thoroughly investigated are the chalcogenides of the
3d transition elements. Among them there exist, in
addition to compounds of simple^ stoichiometric composition such as AX, A2X3, and AX2, phases with extensive regions of homogeneity and compositions that
can be expressed either by the formula AI_,X (0 x
0.5) or AI+,XZ (0 x
1).
Phases corresponding to various values of x have, in
general, structures which can be derived from the NiAs
or Cd(0H)z structure types by subtraction or addition
of metal atoms, respectively. In the first-mentioned case,
the composition of the phase can preferably be expressed by the formula Al-,X, in the second by Al+,X2.
The subtraction or addition of metal atoms is often
accompanied by a lowering of crystal symmetry, leading
to the formation of superstructures and structures in
which the resulting vacancies or the additional metal
atoms are distributed more or less regularly in the lattice.
< <
< <
More detailed investigations have shown that compounds with the exact stoichiometric composition AX
are present only in a few cases. Thus a structure of the
true NiAs-type rarely appears. This type of structure is,
in a more or less modified form, usually associated
either with a subtractive phase, as already mentioned,
or, if an excess of metal atoms is present, with an interstitial phase Al+xX.
Among the chalcogenides of the 3d transition elements
structures of the Cd(OH)z-type have been found mainly
58
for the di-compounds of titanium and vanadium. Here
again small deviations from the stoichiometric composition AX2 apparently occur in most cases, corresponding to a slight excess of metal atoms. Of the remaining
dichalcogenides of the 3d transition elements only the
ditellurides of cobalt and nickel crystallize with the
Cd(OH)2 structure type. The other dichalcogenides of
cobalt and nickel, and the dichalcogenides of manganese
and iron, have structures either of the pyrite or the
marcasite type. Chromium is exceptional as far as it
does not form any di-compound with sulfur, selenium,
or tellurium. For further details about the chalcogenides
of the 3d transition elements, reference may be made to
the comprehensive reviews 11-51.
Among the 4d and 5d transition elements, the platinum
metals in many respects behave somewhat differently
from the 3d transition elements towards the chalcogens,
although many similarities can be foundL11. Just like
the 3d transition elements, the platinum metals form
relatively few compounds with the stoichiometric composition AX. The only compounds of this composition
are two sulfides, PdS and PtS, one selenide, PdSe [GI, and
three tellurides, RhTe, PdTe, and PtTe. Only RhTe and
PdTe possess structures of the NiAs-type. PdS, PdSe,
and PtS have structures of tetragonal symmetry; PtTe
crystallizes in the orthorhombic system.
[ I ] H. Horoldserr, Experientia Suppl. VII, 165 (1957).
[2] H. Hahn, Chemical Society Symposia, Bristol 1958 (chcm.
SOC.,London), Special Publication No. 12, 263 (1958).
[3] J . Flnhaut, Bull. SOC.chim. France 1960, 1282.
[41 F. Jellinek, Ark. Kemi 20, 447 (1963).
[5] A. Kjekshtrs and W. B. Pearsoft, Solid State Chern. I , 83
( I 964).
[6] K . Schiiberr, H . Breitiier, W . Burkhardt, E. Giimel, R . Huufler,
H . L . Lukas, H . Vetter, J . Wegst, and M . IVilke/w. Naturwisscnschaften 44, 229 (1957).
Airyew. Cheur. ;ntermt. Edit.
1 Vul. 5
(1966)
1 Nu.
1
The platinum metals form di-compounds with all three
chalcogens sulfur, selenium, and tellurium. Only three
platinum dichalcogenides, PtS2, PtSe2, and PtTe2, and
the ditellurides of palladium, rhodium, and iridium
(PdTe2, RhTe2, and IrTe2) possess structures of the
Cd(OH)z-type. Most of the other di-compounds of the
platinum metals have structures of the pyrite type; a
few of them have orthorhombic structures closely
related to the pyrite or the marcasite type. Apparently no
rhodium disulfide and n o iridium diselenide with
stoichiometric composition exist. Rhodium and iridium
do, however, form compounds richer in chalcogen than
the di-compounds. In the case of iridium the existence
of even a triselenide (IrSe3) has been shown '1 73. These
chalcogen-rich phases have, as already found by Biltz
et nl. 181, pyrite-like structures of low symmetry.
The platinum metal/chalcogen systems differ also from
corresponding systems of the 3d transition elements in
that phases with composition intermediate between AX
and AX2 exist only in the rhodium and iridium systems
with sulfur and selenium. 'The structures of these phases
are still unknown.
above 640 "C
PdTe2 19-11].
PdTe
changes
continuously
into
With respect to their magnetic properties, the platinum
metal chalcogenides differ considerably from the
chalcogenides of the 3d transition elements. In the lastmentioned compounds,paramagnetism, ferromagnetism,
antiferromagnetism, or ferrimagnetism is found, depending on composition and temperature. The platinum
metal compounds are generally diamagnetic or only
weakly paramagnetic.
11. Chalcogenides of the 4d a n d 5d Transition
Elements of Groups IV to VII
1. Sulfides
The chalcogenides of the 4d and 5d transition elements
of groups 1V to VII of the periodic system have recently
been the object of several investigations. A survey of
the phase and structural relationships in the sulfide
systems is given in Table 1 . The data originate mainly
from Jellinek's review [41.
Table I , Sulfides of the 4d and 5d transition elements.
Elements
I
Subsulfides
A1 .S
Monosulfides
AI-XS
ZrSo.c.n.8
wc- or
eNiAs-type
zrSo.9-1.~
eNaCI-type
NbSo.9
.-850 "C
NbSi.o-1.2
800 "C
NbS-type
rl
Zr
IMo
I
I
NiAs-type
Sesquisulfides
AILXSz-Phases
Trisulfides
ZrS I .7-
-- 1000 "C
2s-Nbl,,Sztype
2.0
ZrS3
ZrSeptype (?)
800 "C
3s-Nb1,.S>-type
2s-NbS2-type
3s-NbSz-type
M0Sl.C
MozS,-type
1
MoS2-type
3s-NbS2-type
amorphous
TcSz
TC
Hf
Heptasulfides
A&
HIS
Type?
HfSi.5
...
Cd(OH)z/NiAs-type
TaSi.48-1.6;
2s-Nb1,~Sztype
TaS1.67
TaS1.75
6 ~ - T a ~ , ~ S z3s-Nbl.,S:type
type
MoS2-type
HfSz
Tc&
Type?
HIS3
2s-N bSr-type
3s-N bS2-type
6s-TaS2-type
ws3
MoS2-type
Re
3s-N bS2-type
ReSz
MoSz-type
3s-NbS1-type
I
[a1 JdIinek 141 also assumes the existence of phas-s of the anproximite co:iiposition MoS:..,
Moreover, no pronounced tendency towards the formation of phases with extended regions of homogeneity is
found among the chalcogenides of the platinum metals.
The same applies even to the rhodium/tellurium and
rhe palladium/tellurium systems, in which phases both
Nith NiAs-like and Cd(OH)z-like structures are present.
More recent investigations have shown, however, that
[7] L . S@vold,Thesis, University of Oslo, 1954.
[8] R . Juzn, 0.Hiilsmnnii, K . Meisel, and W. Biltz, Z . anorg. allg.
Chem. 225, 369 (1935); W. Bilrz, J . Lnar, P. Ehrlich, and K .
Meisel, ihid. 233, 257 (1937); W. Biltz, ihid. 233, 282 (1937).
Angew. Clicni. intcrn(it. Edit.
Vol. 5 (1966) / No. I
2.4
amorphous
ReS, (?)
and ReS2.a-2.4.
Many of the phases have extended regions of homogeneity, and some of them exhibit structures derivable
from certain basic types in similar ways as for the
chalcogenides of the 3d traiisition elements. Only in the
zirconium/sulfur system, however, does a solid solution
phase exist with a structure derived from a Cd(OH)2[9] Z . S. Medvedeva, M . A . Klochko, V. G . Kuznetsov, and S . N .
Aiidreeva, Russ. J . inorg. Chem. (Engl. Transl.) 6 , 886 (1961).
[ lo ] J . Gciggenheinr, F. Hulliger, and J . Miiller, Helv. physica Acta
34,408 (I 96 I).
[I I ] A . Kjekshiis and W. B . Peorsoii, Canad. J. Physics 43, 438
(I 965).
59
type structure by addition of metal atoms [121. There are
no definite data on solid-solubility ranges in the hafnium/sulfur system [131. The different lattice constants of
hafnium disulfide found by Haraldsen, Kjekshus, Rsst,
and Stefensen[14J (a = 3.633 A, c = 5.862 A) on the
one hand, and by McTaggart and Wadsley[l31 (a =
3.635& c = 5.837A) on the other may, however,
indicate that hafnium disulfide is a phase of variable
composition. The presence of a structure of the Cd(0H)ztype for HfS2 and of a Cd(OH)z/NiAs-type structure in
the case of hafnium sesquisulfide[l31 supports this assumption.
The addition of metal atoms, which in hafnium sesquisulfide leads to a structure of the Cd(OH)z/NiAs-type,
does not proceed to the stage where all octahedral holes
between the AX2 layers in the Cd(0H)z-type structure
are occupied by metal atoms, resulting in a compound
with composition HIS and a structure of NiAs-type.
However, hafnium monosulfide has a different structure which is presently unknown 1131.
So far no structure of the NiAs-type has been found in
the zirconium/sulfur system. Instead, zirconium monosulfide belongs to a single-phase region which also includes the composition Zr2S3 and to which a cubic
superstructure of the NaC1-typehas been attributed [121.
For the subsulfide phase ZrSo.5-0.8 H u h et al. [121 proposed a structure of the WC-type. Jellinek [43, however,
does not exclude the possibility that the phase has a
disordered NiAs-like structure.
A structure of the NiAs-type has been found with certainty only for niobium subsulfide NbSG.9 14,151. This is
another example of the tendency of the NiAs-type structure to occur with a somewhat lower chalcogen (X)content than required by the stoichiometric formula AX.
The structures of the Al+xXzphases found in the niobium/sulfur and the tantalum/sulfur systems are derived
not from the Cd(0H)z structure but from structure
types designated by Jellinek [41 as the 2s-Nb1,~Sz-type,
the 3s-Nbl,,Sz-type, and the 6s-Tal+&type. They are
all typical layer structures and differ from the Cd(OH)2type mainly in that the six sulfur atoms surrounding
each metal atom form a trigonal prism instead of an
octahedron. The three structure types differ from each
other in the stacking of the AX2 layers in the direction
of the c-axis. According to the way the layers are
stacked upon each other, different structure types may
arise [4,161.
The disulfides are polytypic with exception of those of
zirconium, hafnium, and technetium. Jellinek [41 reports
five different structures for tantalum disulfide, of which
one is of the Cd(OH)z-type. In addition to the four
structures in Table 1 there is also one in which the TaS2
[I21 H . Hahn, B. Harder, CJ. Mutsclike, and P . Ness, Z . anorg.
allg. Chem. 292, 82 (1957).
[I31 F. K . McTaggart and A . D . Wadsley, Austral. J. Chem. 11,
445 (1958).
[I41 H . Haraldsen, A . Kjekshus, E. Rost, u. A . Steffensen, Acta
chem. scand. 17, 1283 (1963).
[ I51 F. Jellinek, G . Brauer, and H. Miiller, Nature (London) 185,
376 (1960).
1161 B . E. Brown and D. J. Beerntsen, Acta crystallogr. 18, 31
( 1 965).
60
layers are stacked at random. For molybdenum, tungsten, and rhenium disulfides a rhombohedra1 structure
of the 3s-N.bSz-type is known [15,17-191 in addition to the
hexagonal structure of the MoS2-type (called the 2sMoS2-type by Jellinek 141) which has been known for a
long time. The former structure has recently also been
observed in naturally occurring molybdenum disulfide [20-221.
Excepting technetium and possibly rhenium, all thr
metals mentioned in Table 1 form trisulfides. The tri
sulfides of molybdenum and tungsten have so far, however, been obtained only in X-ray amorphous form [4,191.
The existence of rhenium trisulfide has not yet been
ascertained.
Although no complete structure determination has been
carried out, it is suggested that zirconium trisulfide [I21
and hafnium trisulfide 1131 are isostructural with monoclinic ZrSe3, the structure of which has been determined
by Kronert and Plieth [231. Whether or not niobium trisulfide possesses this structure remains doubtful 1241.
Tantalum trisulfide has a structure of orthorhombic
symmetry[251. The fact that rhenium forms a heptasulfide (Re&) was already recognized by Biltz and
Weibke 1261. In the case of technetium, a disulfide of the
MoSz-type and a heptasulfide (TczS7) have been described 1271.
Among the 3d transition elements titanium and vanadium form only sulfur-rich compounds. Thus a trisulfide
of titanium, TiS3, and a tetrasulfide of vanadium, VS4,
and possibly also a pentasulfide, VS5 [2*1, are known.
The structure of vanadium tetrasulfide has been determined by Hellner et al. 1291; it contains groups of two
and two sulfur atoms, corresponding to a formula
V(S2)2 with tetravalent vanadium.
2 . Selenides
The selenides of the 4d and 5d transition elements of
groups TV to VII of the periodic system have not been
investigated in such detail as the sulfides. The results obtained so far are summarized in Table 2.
~
1171 R . E. Bell and R . E. Hefert, J . Amer. chem. SOC. 79, 3351
(1957).
[IS] S. A . Seiniletov, Kristallografiya 6 , 536 (1961); Soviet
Physics, Crystallography (Engl. Transl.) 6, 428 (1962).
1191 J . C. Wildervanck and F. Jellinek, Z. anorg. allg. Chem. 328,
309 (1964).
[20] S. Grneser, Schweiz. mineralog. petrogr. Mitt. 44, 121 (1964).
[21] R . J . Trail/, Canad. Mineralogist 7, 524 (1963).
[22] J . TnkPuchi and W. Nowncki, Schweiz. mincralog. petrogr.
Mitt. 44, 105 (1964).
1231 W. Kronert and K. Plieth, Naturwissenschaften 45, 41 6
(1958); Z . anorg. allg. Chem. 336, 207 (1965).
1241 S . Furuseth and A. Kjekshus, personal communication.
[25] E. Bjerkelund and A . Kjekshus, Z . anorg. allg. Chem. 328,
235 (1964).
[26] W . Biltz and F. Weibke, Z . anorg. allg. Chem. 203, 3 (1932).
1271 R. Colton and R . D. Peacock, Quart. Rev. (chem. SOC. London) 16, 299 (1962).
[28] G. Garrdefro.v, C . R. hebd. Seances Acad. Sci. 237, 1705
(1953).
A . Kutoglu, H . Riisclr, and E. Hell[29] R. Allniurin, J . Baurrrr~~rn,
rrer, Naturwissenschaften 5 1 , 263 (1964).
Arrgew. CIiem. iutcrnnt. Edit.
Vol. 5 (1966) 1 No. 1
Table 2. Selenides of the 4d and 5d transition rleinents
Eleinients
Subselenides
A ] , .Se
Monoselenidea
A I .Se
ZI.
ZrSe,r.6 0 . g
WC-type
ZrSe I.O I.J
NaCI-type
Nb
NbSea.go
Ti<Tea-type
~
Sesquiselenides
A I ixSez-
Diselenides
ASe:
Pentaselenides
A2Se5
Triselenides
ASri
phases
ZrSei.7-2.0
Cd(OH)z-type
N b S e ~13
.
Nb3Se4-type
Heptaselenides
AISe7
Tetraselenides
ASel
ZrSe,
ZrSel-type
=NbSea
Nb S e I . 5s- 2. no
Z s - Nb 1+ ~S 2- t yp
a3,Y
Typ e?
MoSel.: (?)
M O
Hf
HfSe1.r
Type ?
HfSe
Type?
TaSei.2r.t.6n
2s-Nbl, .SItype
Ta
T a S e 1 . m 1.9s
6s-Tal+,Sztype
W
Re
The picture is on the whole similar to that of the sulfides.
It is particularly worth noting that no structure of NiAs
or a related type seems to occur, unless zirconium subselenide ZrSeo.6-0.8 possesses such a structure, in analogy
with Jellinek’s proposal [41 for the corresponding sulfide.
The WC-type given in Table 2 and the other data on the
zirconium/selenium system are due to Hahn and Ness 1301.
MoSe2
Mo2Se5 (?)
MoSz-type
HfSez
Cd(OH)z-type
MoSel
amorphous
HfSe,
ZrSe3-type
TaSe2.w
Cd(OH)z-type
2s-NbSz-type
3s-NhSI-type
4s-TaSez-type
6s-TaS2-type
WSez
MoSz-type
ReSe?
ReSe2-type
TaSei.00
TaSe~type
WSe3
amomhous
It is interesting to compare this structure with a NiAsstructure of the composition TiTe. Fig. 2 shows such
a TiTe structure in [OlO]-projection. It follows from
Figs. 1 and 2 that, apart from slight changes in the
positions of the atoms, the most striking difference between the two structures is that the tellurium atoms
Niobium subselenide, NbSeo.80, crystallizes in the tetragonal TisTe4-type [311. The structure of TijTe4 itself was
first determined by Grmvold, Kjekslzus, and Raaum [321
and is shown in Fig. 1 in [001]-proJection. The titanium
and tellurium atoms are arranged in chains in the direction of the c-axis. The tellurium chains form square
groups, with four chains in each. The titanium atoms
form groups each containing five chains, one chain
being surrounded by the four others at the corners of
a square.
112
0
*’ ‘6
n’
Fig. 2. [OIO] projection of the NiAs-type structure of TiTe [32].
* T i ; 0 Te.
within the quadrilateral of the TiTe structure (shown in
broken lines) have been replaced by titanium atoms in
the Ti5Te4 structure 1321.
Not only the chalcogenides TigTe4, V5S4 [331, V5Se4 [341,
Nb5Se4 [311, and Nb~Te4[311 crystallize with the Ti~Te4-
Fig. I . [OOI] projection of the Ti5Tea structure [32].
0 T i ; 0 Te.
[30] H . Hahn and P . Nrss, 2. anorg. allg. Chem. 302, 37 (1959).
[31] K. Selte and A. Kjekshus, Acta chem. scand. 17, 2560 (1963).
[32] F. Grenvold, A . Kjekshus, and R. Raauin, Acta crystallogr.
14, 930 (1961).
Airgrw. Chem. internat.
Edit.
1 Vul. 5
(1966)
No. I
[33] F. Gronvoid, H . Haraldsen, B. Pedersen, and T. Tufte, Contract A F 61 (052)-178, United States Air Force 1962.
[34] E. Rost and L. Gjertsen, Z. anorg. allg. Chem. 328, 299
(1964).
61
type structure, but also the antimonides Nb5Sb4135,361
and Ta~Sb4[36,371, as well as the arsenides MoSAs4[36,381
and (W, Ti)sAs4 [36J.
The diselenides of zirconium 1301 and hafnium [13J have
structures of the Cd(OH)~-type,just like the corresponding sulfides. One of the five modifications of tantalum
diselenide also belongs to this type of structure 1391. The
other modifications of tantalum diselenide, the modifications of niobium diselenide, and the solid solutions derivable from the disulfides have structures corresponding to those of the analogous sulfides [16,39-411.
Only the structures of the 4s-type are new. The compositions of the phases differ, however, to some extent.
More recent investigations indicate that the 2s-NbS2type is the only structure present in the NbSem1.9-2,0
region, and that the other two structures occur only
at still lower selenium concentrations [421. It is therefore
open to question whether the three structures given
for the diselenide actually are polytypes of the same
phase, or belong to phases of different composition.
A similar situation occurs in case of tantalum diselenides [391. The only structures present for tantalum
diselenide of stoichiometric composition apparently
belong to the Cd(OH)2- and the 4s-NbSe2-types. Further
structures given by Kadijk, Huisrnan, and Jellinek [411
and by Brown and Beerntsen
obviously appear only
at lower concentrations of selenium. Thus, the 2sNbl+xS2-type has been found in the regions
TaSeE1.22-1.60 and TaSem1.95_2.00,and the 6s-TaS2-type
in the region TaSeEl.60_1.9s. These results indicate that
the solid solubility regions NbSe1.ss-2.00 and
TaSel.22-2.00 given in Table 2 actually include several
phases.
The molybdenum and tungsten diselenides have
hexagonal structures of the MoS2-type 143-451.
Rhenium diselenide has a structure of triclinic symmetry [461. The similarity with the Cd(OH)2 structure
can be seen clearly from Fig. 3: both are typical layer
structures. Each rhenium atom is surrounded by six
selenium atoms at the corners of a somewhat distorted
octahedron. Unlike the cadmium atoms in the Cd(OH)2
structure the rhenium atoms are not situated exactly in
the center of the octahedron, but are shifted towards one
face leading to the presence of three shorter and three
longer rhenium-selenium distances, and three significantly shorter rhenium-rhenium distances of 2.646,
[35] S . Furuseth and A. Kjekshus, Acta chem. scand. 18, 1180
( 1 964).
[36] H . Boller and H. Nowotny, Mh. Chem. 95, 1272 (1964).
[37] S . Furuserh, K . Selte, and A . Kjekshus, Acta chem. scand. I Y ,
95 (1965).
[38] P . Jensen, A . Kjekshus, and T. Skansen, ibicl., in press.
[39] E. Bjerkelund and A . Kjekshus, personal communication.
[40] K. Selte and A . Kjekshus, Acta chern. scand. 18, 697 (1964).
[41] F. Kadijk, R . Huisman, and F. Jellinek, Recueil Trav. chim.
Pays-Bas 83, 768 (1964).
[42] K . Selte and A . Kjekshus, personal communication.
[43] L . H . Brixner, J. inorg. nuclear Chern. 24, 257 (1962).
[44] 0. Glemser, H . Sauer, and P . K h i g , Z. anorg. allg. Chem.
257, 241 (1948).
[45] P . B. James and M . 7. Lavik, Acta crystallogr. 16, 1183
(1963).
62
Fig. 3. The ReSe2 structure [46].
.Re;
0 Se.
2.837, and 2.927A. The shortest of these distances is
actually smaller than the rhenium-rhenium distance
found in metallic rhenium (2.75 A). This and other
short rhenium-rhenium distances indicate that chemical
bonds exist between the rhenium atoms in the ReSe2
lattice. These bonds are probably the primary cause of
the distortion of the ReSe2 structure relative to the
Cd(OH)2 structure.
The niobium selenide Nb3Se4 has a hexagonal structure [471 in which each niobium atom is surrounded by
six selenium atoms at the corners of a deformed octahedron (Fig. 4). The whole structure might be regarded
as built up of such octahedra joined by common edges.
Fig. 4. [OOI] projection of the NblSe4 structure
O N b ; 0 Se.
[74].
In analogy with the situation in the ReSe2 structure,
the niobium atoms are not located exactly in the centers
of the octahedra, but are shifted from the center in such
a manner that alternately longer and shorter niobiumniobium distances occur. The short metal-metal distances which are observed indicate that bonding exists
between the niobium atoms.
Just as it is possible in the case of the TisTe4 structure to
show certain similarities in the atomic arrangement of
the NiAs and the TisTe4 structure by comparing corresponding groups of atoms, this can also be done for
the NbsSe4 and Nb3Se4 structures [471. Such a comparison is possible on the basis of Fig. 4 and the TisTe4
[46] N . W. Aleoek and A. Kjekshus, Acta chem. scand. 19, 79
(1965).
[47] K . Selte and A . Kjekshus, Acta crystallogr. 17, I568 (1964).
Angew. Chem. internat. Edit.
1
Vol. 5 (1966)
1 No. I
structure shown in Fig. 1 if one replaces the titanium
and tellurium atoms in Fig. 1 by niobium and selenium
atoms, respectively. The rectangle outlined in Fig. 4
is then seen to correspond to the square in Fig. 1. The
most notable differenceis that the selenium atoms present
in the quadrilaterals shown with broken lines in Fig. 4
are replaced by niobium atoms in Fig. 1 . To convert the
NbsSe4 structure into the Nb3Se4 structure, it is necessary to replace these niobium atoms by selenium atoms,
and, further, to remove some other atoms from the
NbsSe4 structure in combination with a fairly extensive
rearrangement of the atoms.
As in the sulfide systems, several tri-compounds also
exist in the selenide systems; only niobium and rhenium
do not form any triselenide. Instead, these metals form
compounds even richer in selenium, NbSe4 [481 and
Re2Se-r1491, respectively. Niobium tetraselenide occurs
in two or three modifications with structures as yet
unknown. Two of the modifications have tetragonal
symmetry. Dirhenium heptaselenide is apparently
analogous to dirhenium heptasulfide although its existence still cannot be regarded as certain.
The triselenides of molybdenum and tungsten are
amorphous to X-rays L39.441. Zirconium triselenide [301
and hafnium triselenide [I31 are evidently isostructural,
just like the sulfides, and have the monoclinic structure
found by Kronert and Plieth [231 for ZrSe3. The structure
is a typical layer structure (Fig. 5), in which the metal
have structures of the ZrSertype. On the other hand,
it appears doubtful whether NbS3 belongs to this structure type [241.
Tantalum triselenide also has a structure of monuclinic symmetry [251, but it is not of the ZrSeytype. In
this respect, tantalum triselenide shows a similarity to
tantalum trisulfide, which also has a different structure
from that of ZrSe3.
The structure of tantalum triselenide is characterized by
a unit cell containing two crystallographically different
tantalum atoms (I) and (11) and six crystallographically
different selenium atoms, Se(1) to Se(1V) [561. It follows
from Fig. 6 that each tantalum atom is surrounded by
V
@@J
-\.l/4+g5
‘0
Fig. 6. [OlO] projection of the TaSel structure (561.
0 T a ; 0 Se.
Fig. 5. The ZrSe, structure [231.
O Z r ; 0 Se.
atoms are surrounded by four single selenium atoms and
two Se2 groups, resulting in a total of eight selenium
atoms. The selenium-selenium distance in the Se2
groups (2.34 8,) is twice the atomic radius of elemental
selenium. Phases with structures of the ZrSe3-type can
therefore be regarded as partial poly-compounds AX(X2)
with tetravalent metal atoms, divalent chalcogen atoms,
and divalent, dimeric X2 chalcogen groups.
In addition to the compounds already mentioned (ZrS3,
ZrSe3, HfS3, and HfSe3) it is assumed that TiS3[5ol,
ZrTe 1511, US3 [52-531, Use3 [53,541,UTe3 [531, andThTe3rssl
[48] K. Selte and A . Kjekshus, Acta chem. scand. 19, 1002 (1965).
[49] H . V . A. Briscoe, P. L. Robinson, and E. M. Stoddart, J .
chem. SOC. (London) 1931, 1439.
[50] H . Hahn and B. Harder, Z. anorg. allg. Chem. 288, 241
(1956).
[511 H. Hahn and P. Ness, Z. anorg. allg. Chem. 302, 136 (1959).
[52] M. Picon and J. Flahaut, Bull. SOC.chim. France 1958, 772.
[53] F. Grmvold, H . Haraldsen, T . Thurmann-Moe, and T . Tufte,
Contract A F 61 (052)-178, United States Air Force 1962.
Angew. Cliern. intertiat.
,
Edit. 1 Voi. 5 (1966) No . 1
eight selenium atoms. Six of the selenium atoms are at
the corners of a trigonal prism, and two lie outside the
rectangular faces of the prism. The two shortest selenium-selenium distances of 2.53 and 2.66 8, are somewhat greater than the selenium-selenium distances of
2.34 to 2.45 8, found in other compounds of similar
type. However, they might still indicate the existence of
selenium-selenium bonds in TaSe3. Comparison with
the ZrSe3 structure shows that the coordiation of the
metal atoms in the two structures is the same, but in the
ZrSe3 structure all the zirconium atoms are crystallographically equivalent.
Only preparative information is available about the
molybdenum selenides MozSe3 and Mo2SeS [571. The
hafnium selenides HfSe and HfzSe3 have been prepared 1133, but their crystal structures remain unknown.
3 . Tellurides
Table 3 gives a survey of the phase and structural relationships in the telluride systems. The phase relationships are on the whole simpler than in the sulfide and
[54] P . Khodadah and J . Flahaut, C. R . hebd. Seances Acad. Sci.
244, 462 (1957).
[55] J . Graham and F. K . McTaggart, Austral. J . Chem. 13, 67
( I9 60).
[56] E. Bjerkelund and A. Kjekshus, Acta chem. scand. 19, 701
( I 965).
[57] E. Wendehorst, Z . anorg. allg. Chem. 173, 268 (1928).
63
selenide systems. The only phases with extended regions
of homogeneity are the two zirconium telluride phases
ZrTeo.5-0.75 and ZrTe0.8-2.0 [511. The broad regions of
homogeneity attributed to the niobium and tantalum
tellurides by some investigators [43,58,591 have not been
confirmed by others L25,31%47,601.
The zirconium-rich phase ZrTeo.5-0.75 and zirconium
tritelluride correspond in compositions and structural
types to the zirconium-richest and zirconium-poorest in
the sulfide and selenide systems of this metal.
47f'i5
any compound with a greater content of tellurium than
the sesquitelluride [131. In this respect, the hafnium/
tellurium system differs markedly from the zirconium/
tellurium system and also from the other hafnium/
chalcogen systems.
A structure of the Cd(OH)z/NiAs-type has been found
for hafnium sesquitelluride [131. Whether or not this
phase has a region of homogeneity is not known.
Neither is any information available on the structure
of hafnium monotelluride.
Table 3. Tellurides of t h > 4J and 5d transition elements
Mo n o -
A,_,Ter-phases
Ti,Tea-type
HfTe
Type?
N !ZrTeo.a.2.0
Nb~Se4-type
:H)r-type
1
Tetratellurides
ATe4
MoSz-type
HfTe1.s
Cd(OH)2/NiAs-type
TaTe4.00
NbTel-type
ReTez
orthorhomb.
The homogeneity region of the ZrTeo.8~2.0phase is so
wide that it includes the composition of the ditelluride,
the sesquitelluride, the monotelluride, and compositions of still lower tellurides as well [511. Consequently,
the Cd(0H)z-like structure of zirconium ditelluride
changes gradually into a structure of the NiAs-type by
addition of zirconium atoms. The zirconium/tellurium
system differs in this respect from the other two zirconium/chalcogen systems, in which a structure of the
Cd(OH)~/NiAs-typeis present only in a comparatively
narrow concentration range of ZrX1.7-2.0. At the compositions ZrS0.9-1.5 and ZrSe1.0-1.4 ,phases with a
cubic superstructure of the NaC1-type exist [12,301.
Hahn and Ness[5ll do not exclude the existence of a
superstructure of the NiAs-type between ZrTe and
ZrTel.3. Further investigations are therefore needed in
order to clarify the phase and structural relationships
in the whole range from ZrTe to ZrTe2. In other systems
where similar broad regions of homogeneity with continuous transitions from structures of the Cd(0H)z-type
into the NiAs-type were first assumed, it has later been
found that the extended phase regions actually include
several phases with related, but not identical structures.
It is also remarkable that zirconium is the only metal
discussed in Table 3 which forms a tritelluride. Among
the other metals the compounds richest in tellurium are
the ditellurides of molybdenum, tungsten, and rhenium,
and the tetratellurides of niobium and tantalum. Hafnium occupies a special position since it does not form
[58] A. V . Novoselova, L. A . Grigoryan, and Yu. P . Sitnanov,
Dokl. Akad. Nauk SSSR 135, 864 (1960); L . A . Grigoryan, Yu. P .
Simanov, and A . V . Novoselova, ibid. 135, 1133 (1960).
[59] Yu. M . Ukrainskii, A. V. Novoselova, and Yu. P . Sinmnov,
Russ. J. inorg. Chern. (Engl. Transl.) 4, 1305 (1959).
[60] K . Selte and A. Kjekshus, Acta ehern. scand. 18, 690 (1964).
64
Tritellurides
ATe3
NbTe4-type
NbTe4.oo
TaTez.0"
Type?
WTe2
orthorhomb.
Re
1
, Er[q
Ditellurides
ATez
The tellurium-poor niobium phases NbTeo.80 [311 and
NbTel.33 1471 correspond to the analogous niobium
selenides with regard to composition and structure type.
In other respects the phase and structural relationships
of the niobium and tantalum tellurides differ considerably from those of the sulfides and selenides of these
metals. One notes in particular the absence of the broad
regions of homogeneity and the polytypic structures
common to the disulfides, diselenides, and the A I + ~ X ~ phases. In contrast to the disulfides and diselenides and
to what is given in the literature [43,611, the probably isostructural niobium and tantalum ditellurides are not
hexagonal but have a not yet elucidated. structure of
lower symmetry [62,631.
The tetratellurides of niobium and tantalum are isotypic andhave structuresoftetragonal syrnmetry[25,60,641.
Novoselova, Grigoryan, Simanov, and Ukrainskii[58,591
attributed the same symmetry to the phases NbTe2.33-4.0
and TaTe3, which they considered as the phases richest
in tellurium. The unit cell of the tetratellurides of
niobium and tantalum is derived from a structure for
which the subcell is shown in Fig. 7. The a-axis of the
real cell is twice that of the subcell, the c-axis is three
times as long. Each metal atom is surrounded by eight
tellurium atoms in form of a slightly distorted square
antiprism. Each tellurium atom is coordinated to two
metal atoms and eleven tellurium atoms. Five of the
tellurium atoms form a planar, irregular pentagon, and
six form a trigonal prism. The shortest telluriuni[61] M . Chaigneau and M. Santarromana, C . R. hebd. SBances
Acad. Sci. 256, 1797 (1963).
[62] K . Selre, Thesis, University of Oslo, 1964.
1631 E. Bjerkelund, Thesis, University of Oslo, 1964.
[64] E. Bjerkehrnd and A . Kjekshus, J. less-common Metals 7 ,
231 (1964).
A n g e w . Cliem. internnt. Edit.
1 V a l . 5 (1966) N o . I
III. Arsenides and Antimonides of the 4d and 5d
Transition Elements of Groups V to VII
Until recently the arsenides and antimonides of the 4d
and 5d transition elements have received relatively
little attention. However, this situation has now changed
completely. Independently and .almost simultaneously
several research groups have carried out a number of
investigations on the phase and structural relationships
of the arsenides and antimonides of niobium, tantalum,
molybdenum, and tungsten. The investigations have
led to essentially consistent results.
I
11977/
Fig. 7. [OOI] projection of the NbTed structure 1601.
ONb; O T e
tellurium distance (2.867 A for NbTe4 and 2.790 A for
TaTe4) allows the conclusion that tellurium-tellurium
bonds exist in both tetratellurides. Although a certain
similarity is present, the structure of the tetragonal
modification of niobium tetraselenide [481 differs from
the structures of the tetratellurides of niobium and
tantalum.
Table
ments
I
4.
Arsenides and antimonides of the 4d and 5d transition elements of groups V to VII of the periodic system.
Arsenides
NbAs2
NbAsz-type
[35, 72, 73a,
73cl
TaAs2
NbAsz-type
137, 721
MoAsz
NbAsz-type
[ 3 6 , 38, 77,
78,801
NbAs-type
135, 71, 72,
I-
MO
I-
W
Re
137, 71, 721
MosAs4
I
MozAs3-type
[38, 78, 791
I
F$fP,pe
135, 73a-761
I
Antimonides
:i:g:type
135, 36, 73al
NbSbz
NbAsz-type
[35, 73a, 73cl
ta5b2
NbAsz-type
137, 771
l
l
M03Sb7
IrsGe7-type
1381
WAsz
NbAs2-type
136, 38. 77, 781
Unlike the other tungsten dichalcogenides and the
molybdenum dichalcogenides, tungsten ditelluride,
which is the only intermediate phase in the tungsten/
tellurium system, does not have a structure of the MoS2type but an as yet not elucidated orthorhombic structure [43,65,661. Like tungsten, rhenium forms a ditelluride ReTe2 with an orthorhombic structure that also
has not yet been determined 1671.
Molybdenum ditelluride and molybdenum sesquitelluride were first described by M o r e t t e [651 whose
results were confirmed by Perotinen and Newnham 1681.
Molybdenum ditelluride has a structure of the MoS2type [68-701; the structure of molybdenum sesquitelluride remains to be determined.
[65] A . Morette, Ann. Chimie ( I 1) 19, 130 (1944); C. R. hebd.
Seances Acad. Sci. 216, 566 (1943).
[66] 0. Knop and H . Haraldsen, Canad. J. Chern. 34, 1142 (1956).
[67] S. Furuseth and A . Kjekshus, Acta chem. scand., in press.
Angew. Chem. internat. Edit.
A survey of the phases and structure types that can be
regarded as established is given in Table 4. In addition
to the systems mentioned, the tungsten/antimony system
and the bismuth systems of niobium, tantalum, molybdenum, and tungsten have also been investigated [381. N o
intermediate phases were detected in any of these systems. The existence of the phases MoAs, MoAs1.04 w
MoqAsg, W2As and W~ASS,described by Boller and
Nowotny[361 has not been confirmed, neither by Taylor,
Calvert, and Hunt [781, nor by Jensen, Kjekshus, and
Skansen [381. The W4Ass phase evidently is identical,
, Vol. 5 (1966) / No. I
[68] D . Perotinen and R . E. Newnham, Acta crystallogr. 14, 691
(1961).
[69] V. M. Goldschmidt, Trans. Faraday SOC.25, 279 (1929).
[70] 0. Knop and R . D . MacDonald, Canad. J. Chem. 39, 897
(1961).
[71] H . Boller and E. Parthd, Acta crystallogr. 16, 1095 (1963).
[72] G. S. Saini, L. D . Calvert, and J . B. Taylor, Canad. J. Chem.
42, 630 (1964).
[73] S. Furuseth and A . Kjekshus, a) Nature (London) 203, 5 I2
(1964); b) Acta crystallogr. 17, 1077 (1964); c) ibid. 18, 32011965).
[74] B. T. Matthias, E. A . Wood, E. Corenrwit, and V. B. Bala, J.
Physics Chem. Solids I, 188 (1956).
[75] E. A. Wood, V . B. Compton, B. T . Matthias, and E. Corenr w i t , Acta crystallogr. 11, 604 (1958).
[76] M. V. Newitt, Trans. metallurg. SOC.AlME 212, 350 (1958).
[77] F. Hulliger, Nature (London) 204, 775 (1964).
[78] J. B. Taylor, L . D . Calvert, and M . R . Hunt, Canad. J. Chem.
43, 3045 (1965).
[79] P . Jensen, A . Kjekshus, and T . Skansen, Acta chem. scand.
19, 1499 (1965).
[SO) P . Jensen and A . Kjekshus, Acta chem. scand. 18, I798 (1964).
65
however, with the W2As3 phase of the last-mentioned
authors. The same probably applies to the Mo4Ass
phase, which should accordingly be regarded as MozAs3.
Table 4 shows that niobium and tantalum form arsenides and antimodnies of identical compositions. The
compounds have no detectable regions of homogeneity
and can be regarded as stoichiometric[38l.All compounds
of corresponding composition have structures of the
same type.
A structure of the p-W-type, present for Nb3Sb and
Ta3Sb, has previously been found for about 40 to 50
different compounds. The structures are characterized,
inter alia, by remarkably small metal-metal distances.
This also applies to Nb3Sb and Ta3Sb. Thus the shortest
niobium-niobium distance is 2.632 A in Nb3Sb [351,
while in metallic niobium it is 2.858 A[81,821. In Ta3Sb
and metallic tantalum, the shortest tantalum-tantalum
distances are 2.632 A [371 and 2.863 A [83J, respectively.
The tetragonal structure of niobium monoarsenide has
been determined independently by BoIIer and Parthe [711
and by Furuseth and Kjekshus [73a, bl. Each atom is surrounded at equal distances by six nearest neighbors of
the other kind (Fig. 8). The structure may be considered
as built up of almost regular, trigonal niobium prisms
with an arsenic atom in the center. The prisms are
rotated and displaced with respect to each other. A
structure of the same type is found also for tantalum
monoarsenide and for the monophosphides of niobium
and tantalum [71,841.
All di-compounds of Table 4 have the structure type
first found for NbAs2[73a$73cl. The same type is suggested for VP2, VAs2, NbPz, TaP2, and ~-WP2[771.
A [010]-projection of the NbAs2 structure is shown in
Fig. 9. Each niobium atom is surrounded by six arsenic
atoms at the corners of a trigonal prism and by two
112
0
11(9191
Fig. 9. [OlO]projection of the NbAsz structure [73cl.
.Nb;
0 As.
additional arsenic atoms and one niobium atom outside the rectangular faces of the prism. Two crystallographically different arsenic atoms, As (I) and As (11),
are present. The arsenic atoms (I) have five niobium
atoms as their nearest neighbors, forming a distorted
square pyramid with one additional arsenic atom (I)
outside the base of the pyramid. The arsenic atoms
(11) are coordinated to three arsenic atoms (11) and three
niobium atoms. The arrangement of the arsenic atoms
(11) produces alternating longer and shorter arsenic (11)arsenic (11) distances. In NbAs2 the shorter distances are
2.446A, while in NbSb2 the shorter antimony (11)antimony (11) distances are 2.72 A [73cl. The corresponding distances in TaAs2 and TaSb2 are 2.42 and
2.65 A, respectively [371. Compared to the shortest bond
distances in metallic arsenic (2.507 A) and antimony
(2.904 A) [851 indications are that half of the arsenic and
antimony atoms in the diarsenides and diantimonides
of niobium and tantalum are bound in pairs, corresponding to the formulae
-4 -3
Nbz(As2) As2,
+5
+5
-4
-3
Nbz(Sb2) Sb2,
-4 -3
Ta2(As2) As2
+5
and
-4 -3
Taz(Sb2) Sb2.
+5
In agreement therewith, it has been shown that the
compounds, are diamagnetic. The mono-compounds
NbAs-and- TaAs*also are diamagnetic. On the other
hand, the antimonide phases NbsSb4, TasSb4, Nb,Sb,
and Ta3Sb with higher metal contents exhibit slight,
almost temperature-independent paramagnetism, corresponding to a more metallic bond character [35,371.
Fig. 8. The N b A s structure [711. Small circles, Nb; large circles, As.
[ X I ] M . C . Neuberger, Z . Kristallogr., Mineralog. Petrogr.,
Series A, 93, 158 (1936).
[X2] J. W. Edwards, R . Speiser, and H . L . Johnston, J . appl.
Physics 22, 424 (1951).
1x31 H . E . Swanson and E. Tatge, Nat. Bur. Standards, Circ.
539 I, 29 (1953).
1841 S. Rundqvist, Ark. Kemi 20, 67 (1962).
66
Besides the diarsenides MoAs2 and WAs2 of the NbAs2
type, molybdenum and tungsten form sesquiarsenides
MozAs3 and WzAs3 of monoclinic symmetry 138, 78,793.
Molybdenum also forms an arsenide MosAs4, of the
Ti~Tectype,and an antimonide Mo3Sb7. This antimonide, and the rhenium arsenide of corresponding
composition Re3As.1, belong to a structure type first
found for Ir3Ge7 by NiaII861.
Received. September 16th, 1965 [A 497/273 I E ]
German version Angew Chem 78, 64 (1966)
1 ranslated by Express Translation Service, London
[85] W. B. Pearson: Handbook of Lattice Spacings and Structures of Metals and Alloys. Pergamon Press, London-New York
1958.
1861 0. Nial, Svensk kem. Tidskr. 59, 172 (1947).
Angew. Chem. internat. Edit. 1 Vol. 5 (1966)
1 No.
I
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