Regularities of thermal decay of carbonyl chalcogenide metal clusters

Article abstract of DOI:10.1023/A:1022444231122

The thermal decay of 19 individual carbonyl homo- and heterochalcogenide clusters with different M/X ratios (M = Fe, Mn, Pt, Cr, W, Mo, Re, Ru; X = S, Se, Te) was studied by differential scanning calorimetry and thermogravimetry. The process is stepwise a

Full text of DOI:10.1023/A:1022444231122

Russian Chemical Bulletin, International Edition, Vol. 52, No. 1, pp. 109—115, January, 2003
109
Regularities of thermal decay of
carbonyl chalcogenide metal clusters
ꢀ
A. A. Pasynskii, Zh. V. Dobrokhotova, Yu. V. Torubaev, N. I. Semenova, V. M. Novotortsev
N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
3
1 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (095) 954 1279. Eꢀmail: aapas@rambler.ru
The thermal decay of 19 individual carbonyl homoꢀ and heterochalcogenide clusters with
different M/X ratios (M = Fe, Mn, Pt, Cr, W, Mo, Re, Ru; X = S, Se, Te) was studied by
differential scanning calorimetry and thermogravimetry. The process is stepwise and occurs at
relatively low temperatures (100—350 °C). The general fact of incomplete removal of carbon
monoxide (due to the formation of carbide and oxide impurities) during thermolysis of сarbonyl
chalcogenide clusters with the M : X ratio greater than 1 was elucidated. Conversely, when
M : X < 1 (or at any M/X ratio for clusters containing methylcyclopentadienyl groups), pure
metal chalcogenides are formed.
Key words: thermal decay, carbonyl chalcogenides, heterometallic clusters.
The synthesis of inorganic chalcogenides of a speciꢀ
fied complex composition is a problem of modern mateꢀ
rial science. Chalcogenide complexes of some transition
metals are used to prepare solidꢀstate chalcogenide mateꢀ
rials for electronic engineering.1 Heterometallic chalcoꢀ
genide clusters appear to be quite promising precursors in
the synthesis of polymetallic chalcogenides; however,
there are no examples describing the use of these comꢀ
pounds, as these clusters are difficult to prepare.
This work outlines the results of a study of thermal
decomposition of 19 carbonyl chalcogenide clusters of
transition metals including heterometallic and heteroꢀ
chalcogenide clusters, whose structures have been deterꢀ
mined by Xꢀray diffraction analysis.
E = S (1), Se (2), Te (3)
,2
Bond
d/Å
1 3
2 3
3 4
Fe(2)—Fe(3)
Fe(1)—Fe(3)
2.590
2.595
2.645
2.657
2.740
2.754
6
previous study using powder Xꢀray diffraction analysis of
the decomposition products.
Results and Discussion
Heating of all of the clusters studied leads to stepwise
elimination of the carbonyl groups and organic fragments;
the presence of carbides or oxides in the final product of
thermal decay depends on the metal/chalcogen ratio in
the cluster.* In the case of starting iron chalcogenide
carbonyls Fe E (CO) , where E = S, Se, Te (1—3, reꢀ
(
(
1)
2)
3
2
9
spectively),3 prepared by a known procedure, the Fe : E
ratio is 3 : 2 and decomposition proceeds stepwise by reꢀ
actions (1)—(3).
,4
5
Thermolysis is accompanied by energy absorption. The
formation of a mixture of inorganic chalcogenides, oxꢀ
ides, and carbides upon decomposition of iron carbonyl
selenide and carbonyl telluride was demonstrated in our
*
The metal : chalcogen ratio is indicated in parentheses at each
reaction equation.
(3)
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 103—109, January, 2003.
1
066ꢀ5285/03/5201ꢀ109 $25.00 © 2003 Plenum Publishing Corporation

110
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 1, January, 2003
Pasynskii et al.
7
ously described procedure, follows an almost identical
route, and the thermal effect of the reaction has the
same sign:
(
4)
Thermolysis of homoselenide carbonyl clusters,
namely, iron ruthenium RuFe Se (CO) (5) and iron
2
2
9
molybdenumꢀcontaining Fe MoSe (CO) (6) clusters,
2
2
10
and of the homotelluride iron tungstenꢀcontaining carboꢀ
nyl cluster Fe WTe (CO) (7), which were prepared preꢀ
2
2
10
7
viously, is also stepwise and is described by the reacꢀ
tions (5)—(7):
(
5)
Comꢀ
pound
Bond
d/Å
Ref.
7
4
Fe—Fe
Se—Mn(СО)5
2.623(3)
2.516
Sе—Mn(СО)3
Fe→Mn(СО)3
2.394
2.709
(6)
5
6
Mo—Fe
Se—Mo
2.793, 2.823
2.544
7
8
Fe—Fe
Fe—Ru
Se—Ru
2.672
2.720
2.422—2.435
ꢀ
7
W—Fe(1)
W—Fe(2)
W—Te(1)
W—Te(2)
Fe(1)—Te
2.925
2.898
2.736
9
7
(
7)
2.736
2.537—2.549
However, in this case, the thermal effects of the proꢀ
cesses are different: the onset of the decay is accompanied
by a substantial heat evolution but this amount of energy
is insufficient to make up for the energy spent for eliminaꢀ
tion of the carbonyl groups in the second step; therefore,
the thermograms display endothermic dips on exothermic
peaks.
8
Sn—Se
Fe—Fe
2.539—2.549
2.544, 2.521
ꢀ
Fe—W—Fe angle 80.9°.
The thermal decay* of the iron manganese selenide
carbonyl Fe Mn Se (CO) (4), prepared by a previꢀ
2
2
2
14
Similar thermal effects are observed in the case of the
pentanuclear tinꢀcontaining iron selenium carbonyl clusꢀ
*
Apparently, in this case and in other examples, mixtures of
metal chalcogenides, carbides, and oxides are also formed at the
final stage; however, this was not confirmed experimentally.
Therefore, the number of CO molecules not evolved during the
decay is shown in braces.
ter Fe Se (CO) Sn (8) prepared by a previously described
4
4
12
7
procedure; however, the transition metal to chalcogen
ratio in this cluster is equal to unity and carbon monoxide

Regularities of thermal decay of metal clusters
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 1, January, 2003
111
is totally evolved; the final product does not contain carꢀ
bide or oxide impurities:
This outcome differs from that observed in thermolyꢀ
sis of the carbonyl clusters (C H )PtFe Е (CO) (E =
8
12
2
2
6
S (12), Se (13), Te (14)) synthesized by a previously
1
1
described procedure. Although the energy patterns that
accompany the decay of these complexes and the platiꢀ
num carbonyl telluride are qualitatively the same, the
transition metal to chalcogen ratio is 3 : 2; therefore, these
three compounds undergo successive elimination of the
organic ligands and only four of the six carbonyl groups
(reactions (12)—(14)):
(
8)
Thermal decay of the pentanuclear iron molybdenum
selenide telluride cluster Fe MoTe Se (CO) (9), synꢀ
thesized by a known procedure, is similar, regarding the
pattern of energy changes, to the decay of the aboveꢀ
noted trinuclear iron molybdenum and iron tungsten chalꢀ
cogen carbonyls and proceeds by reaction (9).
4
2
2
14
7
(
12)
(
9)
The thermal transformations of the binuclear phenylꢀ
tellurylcarbonylmolybdenum [Mo(PhTe)(CO) ] (10),
4
2
obtained by a known procedure,1 resemble in the pattern
of energy changes the thermal decay of chalcogenide iron
molybdenum carbonyls. However, in this case, the moꢀ
lybdenum to tellurium ratio is equal to unity and the
pyrolysis is accompanied by complete elimination of all
carbonyl groups and organic ligands, giving rise to pure
molybdenum telluride (MоTe).
0
(
13)
(
14)
(
10)
A similar pattern of energy changes, but with a more
clearly defined transition of the exotherm in the beginꢀ
ning of the decay into an endotherm in the middle of the
temperature range of thermolysis was noted for the platiꢀ
num carbonyl telluride Pt Te (CO) (11) synthesized by
Note that the replacement of cyclooctadiene (C H )
8
12
πꢀcoordinated to platinum by dicyclopentadiene
7,12
(
C H )
(compounds 15, 16) barely changes the route
1
0
12
of the decay (reactions (15), (16)).
2
2
4
7
a known procedure.
In this case, the Pt : Te ratio is also equal to unity and
CO molecules are completely split off; the platinum telluꢀ
ride thus formed contains no carbide or oxide impurities.
(
11)
(
15)

112
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 1, January, 2003
Pasynskii et al.
Bond
d/Å
12 11
13 11
14 11
15 12
16 7
Comꢀ
pound
Bond
d/Å
Ref.
Fe—Fe
Fe—E
2.506
2.285
2.295
2.288
2.537
2.393
2.395
2.398
2.403
—
2.612(2)
2.559(1)
2.590(1)
2.572(1)
2.582(1)
—
2.515
2.276
2.309
2.299
2.303
3.028
2.543
2.373
2.427
2.413
2.454
3.169
1
0
7
Мо—Мо
Мо—Те
Cr—Mn
3.116
2.751—2.761
3.0239
10
13
1
Pt—E
2
.291
—
*
The geometry of the metal—chalcogen core
Pt—Fe(1)
was determined by Xꢀray diffraction analysis,
but due to the disorder of the chalcogen posiꢀ
tions, the M—M and M—X distances were not
determined.7
** Assumed based on the data of IR spectra and analogy with the
1
4
structure of (PPh ) Pt Te
The structure of complex 11 was not
7
3
4
2
2
determined by Xꢀray diffraction.
(
16)
Chalcogenide carbonyl clusters 17—19, containing
(
18)7
methylcyclopentadienyl groups, decompose with comꢀ
plete loss of all the carbonꢀcontaining fragments and CO
groups at any M : X ratio.
(
19)7
For processes that follow reactions (17)—(19), the
first step of the decay is accompanied by appreciable enꢀ
(
17)13

Regularities of thermal decay of metal clusters
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 1, January, 2003
113
Q
a
Q
b
T
T
Q
c
Q
d
Comꢀ
pound
Bond
d/Å
Ref.
7
1
8
Fe—Fe
Cr—Cr
Fe—Se
Cr—Se
Fe—Se
Se—Re
Fe—Fe
2.618—2.706
2.763
2.465
T
T
2.447—2.460
2.377—2.383
2.589—2.590
2.515
1
9
7
Fig. 1. Averaged patterns of the temperature dependence of the
heat flux (Q) during the thermal decay of 3dꢀmetal (a), 4dꢀ and
5dꢀmetal (b), Ptꢀcontaining (c), and methylcyclopentadienylꢀ
containing (d) carbonyl chalcogenide clusters.
ergy absorption; on further heating, the thermograms disꢀ
play exotherms with endothermic dips.
panied by heat absorption, while further decomposition
gives rise to a complex exotherm (reactions (17)—(19)).
The energy patterns i and ii can be interpreted resortꢀ
ing to the views on the parameters and types of M—M
bonds in carbonyls. It appears probable that during
stepwise decarbonylation, additional M—M, M—X,
M—O, and M—C bonds are formed.
We found that thermolysis of the clusters we studied
takes place at relatively low temperatures, 100—350 °C.
Four types of energy patterns of the decay (i.e., the
schemes of energy evolution and absorption during heatꢀ
ing) can be clearly distinguished for these compounds:
(
i) only endotherms appear on thermograms during
For 3dꢀmetal clusters, the M—M bonds are much
weaker than for 4dꢀ and 5dꢀmetal clusters; in addition, in
the latter case, multiple Mо—Mо and W—W bonds are
readily formed. Therefore, for the firstꢀgroup clusters, the
energy spent for decarbonylation is not made up for by
the energy evolved due to formation of new M—M bonds,
whereas for secondꢀgroup clusters, such a compensation
is quite probable.
the elimination of carbonyl groups (Fig. 1, а) (reacꢀ
tions (1)—(4)) for clusters of 3d elements;
(
ii) thermal decay is accompanied by a complex
exotherm (Fig. 1, b), which can be interpreted as an
exotherm with endothermic dips; this type of decay is
typical of 4dꢀ and 5dꢀmetal carbonyl chalcogenides (reꢀ
actions (5)—(10));
(
iii) thermolysis starts with pronounced heat evoluꢀ
The pattern iii of energy loss can be explained by
assuming that elimination of the diene ligand (C H or
tion, but before it ends, a substantial endotherm appears,
and only after that, the exothermic effect is completed
8
12
C H ) from the platinum atom is followed by the forꢀ
1
0
12
(
Fig. 1, c), reactions (11)—(16); this pattern is characterꢀ
istic of Ptꢀcontaining clusters;
iv) combination of the first two cases (Fig. 1, d), in
particular, the primary loss of carbonyl groups is accomꢀ
mation of new Pt—Pt and Pt—X bonds; however, the
concomitant amount of energy does not make for the
energy spent for further elimination of CO molecules;
therefore, energy absorption starts to predominate.
(

114
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 1, January, 2003
Pasynskii et al.
Of particular interest is the clearꢀcut dependence of
the final product of thermolysis of carbonyl chalcogenide
clusters on the transition metal to chalcogen atomic raꢀ
tio (M : X).
(20)
(
(
(
21)
22)
23)
Bond
d/Å
2
0 15
21 15
22 16
23 16
24 16
Cr—Te
W—Te
Te—Te
2.679
—
2.718
—
2.810
2.737
2.656
—
2.812
2.720*
2.720*
2.828(2)
—
2.779
2.808
*
Disordered.
(
(
(
24)
25)
26)
For any of the carbonyl chalcogenide clusters studied,
complete decarbonylation does not take place if the
M : X ratio is greater than unity (reactions (1)—(7), (9),
(
12)—(16), (26)). In the case where M : X < 1 (reacꢀ
tions (8), (10), (11), (17), (18), (20)—(25)), the carbonyl
groups split off completely, irrespective of the nature of
the chalcogen atom. When the cluster contains methylꢀ
cyclopentadienyl ligands, pure chalcogenides are formed
even with M : X > 1.
Bond
d/Å
2
5 17
26 17
Co—Co
Co—Te
Te...Te
2.664(5), 2.674, 2.544
2.516(4)—2.618
—
2.590—2.622
—
3.063
These regularities can be explained in terms of
the tendency of transition metal atoms to compensate
the electron deficiency in each step of thermal decay
with ligand elimination. When the ratio M : X > 1,
the electronic deficiency is compensated by the
formation of σꢀ,πꢀbonded CO bridges of type А,
Previously, we observed this dependence in the study
of the thermal decay of monoꢀ15 and binuclear diphenyl
telluride complexes with chromium and tungsten pentaꢀ
carbonyls 20—24 (reactions (20)—(24), respectively) and
a trinuclear cobalt phenyltelluride carbonyl cluster (25)
and tetranuclear cobalt bisꢀtelluride carbonyl17 (26) (reꢀ
actions (25) and (26), respectively):
16
1
8
Cp Nb(µꢀCO)(σ,πꢀCO)Mo(CO)Cp, or of type B,
2
1
9
Cp Nb (CO) , in which weakening of the C—O bond
3
3
7
results in easy cleavage of carbon oxide to give carbides
and oxides.

Regularities of thermal decay of metal clusters
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 1, January, 2003
115
References
1
2
3
. M. L. Steigerwald and L. E. Brus, Acc. Chem. Res.,
990, 23, 83.
. S. V. Larionov and S. M. Zemskova, Ros. Khim. Zh., 1996,
0, 171 [Mendeleev. Chem. J., 1996, 40 (Engl. Transl.)].
. R. Seidel, B. Schnautz, and G. Henkel, Angew. Chem., Int.
Ed. Engl., 1996, 35, 1710.
1
4
When the ratio M : X < 1, the electron deficiency is
4. H. Schumann, M. Magerstadt, and J. Pickardt, J. Organomet.
Chem., 1982, 240, 407.
5
6
. W.Hieber and J. Gruber, Z. Anorg. Allg. Chem., 1958, 296, 91.
. Zh. V. Dobrokhotоva, A. A. Pasynskii, A. V. Saushev, N. I.
Semenova, and Yu. V. Torubaev, Abstrs. Int. Conf. "New
Approaches in Coordination and Organometallic Chemistry.
Look from 21ꢀth Century", Nizhny Novgorod, 2002, 25.
. N. I. Semenova, Ph.D Thesis, Institute of General and Inorꢀ
ganic Chemistry, Moscow, 2002, 78 pp. (in Russian).
made up for by additional πꢀbonding
the lone electron pairs of the chalcogen atoms without the
formation of σꢀ, πꢀCO bridges. Finally, in the presence of
through
5
ꢀelectronꢀdonating methylcyclopentadienyl ligands, the
electron deficiency arising due to the elimination of carꢀ
bonyl groups may be compensated by transformation of
the rings into coordinated 6ꢀelectronꢀdonating fulvene
C H CH and formation of M—H bonds
7
8. P. Mathur, P. Sekar, C. V. V. Satyanarayana, and M. F.
Mahon, J. Chem. Soc., Dalton Trans., 1996, 2173.
5
4
2
9
. P. Mathur, D. Chakraborty, Md. M. Hossain, and R. S.
Rashid, Inorg. Chem., 1992, 31, 1106.
1
1
0. S. E. Nefedov, B. I. Kolobkov, A. A. Pasynskii, I. L.
Eremenko, and I. D. Sadekov, Zh. Neorgan. Khim., 1992,
3
7, 335 [Russ. J. Inorg. Chem., 1992, 37 (Engl. Transl.)].
1. A. A. Pasynskii, N. I. Semenova, Yu. V. Torubaev, P. V.
Belousov, K. A. Lysenko, and Zh. V. Dobrokhotova, Izv.
Akad. Nauk, Ser. Khim., 2001, 2115 [Russ. Chem. Bull., Int.
Ed., 2001, 50, 2215].
Therefore, even with M : X > 1, there is no need for
the formation of σꢀ, πꢀCO bridges until the carbonyl
groups have completely split off.
1
2. A. A. Pasynskii, N. I. Semenova, Yu. V. Torubaev, and K. A.
Lysenko, Zh. Neorgan. Khim., 2001, 46, 1987 [Russ. J. Inorg.
Chem., 2001, 46 (Engl. Transl.)].
This unusual but a rather general regularity of incomꢀ
plete elimination of CO groups in the thermolysis of tranꢀ
sition metal carbonyl chalcogenide clusters with M : X > 1
and formation of pure metal chalcogenides from clusters
with M : X < 1 can prove quite useful for controlling the
formation of oxide and carbide impurities in the inorganic
chalcogenides formed upon the pyrolysis of such clusters.
th
1
1
3. A. A. Pasynskii and Yu. V. Torubaev, Abstrs. of 34 Int. Conf.
on Coord. Chem., 2000, Edinburg, Scotland, P0815.
4. D. Fenske, H. Fleischer, H. Krautscheid, J. Magull, C. Oliver,
and S. Weisgerber, Z. Naturforsch., Teil B., 1991, 46, 1384.
15. A. A. Pasynskii, Yu. V. Torubaev, A. V. Drukovskii, I. L.
Eremenko, D. Vegini, E. V. Krasil'nikova, V. I. Privalov,
A. I. Yanovskii, and Yu. T. Struchkov, Zh. Neorgan. Khim.,
1
997, 42, 42 [Russ. J. Inorg. Chem., 1997, 42 (Engl. Transl.)].
Experimental
1
1
1
6. A. A. Pasynskii, Yu. V. Torubaev, I. L. Eremenko, D. Vegini,
S. E. Nefedov, A. I. Yanovskii, and Zh. V. Dobrokhotova,
Zh. Neorgan. Khim., 1996, 41, 2006 [Russ. J. Inorg. Chem.,
The main experimental methods used in the study were difꢀ
ferential scanning calorimetry (DSC) and thermogravimetry
TG). Measurements were carried out on a Mettler TАꢀ3000
thermal analyzer using DSCꢀ20 and TGꢀ50 modules, which
were described in previous publications.
carried out with a constant heating rate of 5 K min– in a dry
argon atmosphere. Samples were heated either in aluminum
containers (DSC) or in alundum crucibles (TG). The sample
weight did not exceed 10 mg. The variation of the weight during
heating was monitored directly with the TGꢀ50 module with an
accuracy of ±2•10–3 mg and in DSC studies of the stepwise
decomposition of the compounds over fixed temperature ranges.
The accuracy of temperature measurement at the anomalous
points in the thermograms was ±0.5°. At least four experiments
by each of the procedures was carried out for every compound.
The final results were obtained by statistical processing of the
experimental data.
1
996, 41 (Engl. Transl.)].
(
7. A. A. Pasynskii, Yu. V. Torubaev, K. A. Lysenko, A. Yu.
Lyakina, Zh. V. Dobrokhotova, and V. M. Novotortsev,
Zh. Neorgan. Khim., 1998, 43, 939 [Russ. J. Inorg. Chem.,
2
0,21
Experiments were
1
1
998, 43 (Engl. Transl.)].
8. A. A. Pasynskii, Yu. V. Skripkin, I. L. Eremenko, V. T.
Kalinnikov, G. G. Aleksandrov, V. G. Andrianov, Yu. T.
Struchkov, J. Organomet. Chem., 1979, 165, 49.
19. W. A. Herrmann, M. L. Ziegler, K. Weidenhammer, and
H. Biersack, Angew. Chem., Int. Ed. Engl., 1979, 18, 960.
0. W. Hemminger and G. Hohne, Calorimetry, Verlag Chemie,
GmbHDꢀ6940, Weinheim, 1984.
1. I. A. Kiseleva and L. P. Ogorodova, Termokhimiya mineralov
i neorganicheskikh materialov [Thermochemistry of Minerals
and Inorganic Materials], Nauchnyi mir, Moscow, 1997,
2
2
2
55 pp. (in Russian).
This work was financially supported by the Russian
Foundation for Basic Research (Projects No. 02ꢀ03ꢀ
3
3041, 02ꢀ03ꢀ06170, 02ꢀ03ꢀ06171, and MPꢀ99ꢀ2).
Received October 4, 2002