Synthesis and structural characterization of some selenoruthenates and telluroruthenates

Article abstract of DOI:10.1021/ic0483646

The reaction of solid [RuClCp(PPh₃)₂] with TeSe ₃^2- or Se_n^2- in DMF leads to the formation of [RuCp(PPh₃)(μ₂-Se₂)] ₂ (1). In the structure of this compound the two bridging Se ₂ groups lead to a six-membered Ru₂Se₄ ring in a chair conformation. Attached to each Ru center is a PPh₃ ligand in an equatorial position and a Cp ring in an axial position. The compound is diamagnetic. The compound [Ru₂Cp₂(μ₃-Se ₂)(μ₃-Se)]₂ (2) is obtained under similar conditions in the presence of air. This structure comprises a centrosymmetric Ru₄Se₆ dimer formed from the two bridging Se groups and the two bridging Se₂ groups. Each Ru center is π-bonded to a Cp ring. The reaction of solid [RuClCp(PPh₃)₂] with a Te _n^2- polytelluride solution in DMF leads to the diamagnetic compound [(RuCp-(PPh₃))₂(μ₂-(1,4-η:3,6- η)Te₆)] (3). Here the Ru centers are bound to a bridging Te ₆ chain at the 1, 4, 3, and 6 positions, leading to a bicyclic Ru₂Te₆ ring. Each Ru atom is bound to a Cp ring and a PPh₃ group. This dimer possesses a center of symmetry. The structure of 3 is the first example of a bicyclic complex where fusion occurs along a Te-Te bond. If the same reaction is carried out in DMF/CH₂Cl ₂, rather than DMF, then [(RuCp(PPh₃))₂-(μ2- (1,4-η:3,6-η)Te₆)]·CH₂Cl₂ (4) is obtained. In the solid state it possesses the same Ru₂Te₆ structural unit as does 3, but the unit lacks a crystallographically imposed center of symmetry. The electronic structures of 3 and 4 have been analyzed with the use of first principles density functional theory. Bond order analysis indicates that the Te-Te bond where fusion occurs has a shared bonding charge of about 2/3 of that found for Te-Te single bonds.

Full text of DOI:10.1021/ic0483646

Inorg. Chem. 2005, 44, 3441−3448
Synthesis and Structural Characterization of Some Selenoruthenates
and Telluroruthenates
Sergey M. Dibrov,† Bin Deng,† Donald E. Ellis,‡ and James A. Ibers*,†
Department of Chemistry and Department of Physics & Astronomy, Northwestern UniVersity,
2145 Sheridan Road, EVanston, Illinois 60208-3113
Received November 18, 2004
2-
2-
The reaction of solid [RuClCp(PPh3)2] with TeSe3 or Sen in DMF leads to the formation of [RuCp(PPh3)(µ2
-
Se2)]2 (1). In the structure of this compound the two bridging Se2 groups lead to a six-membered Ru2Se4 ring in
a chair conformation. Attached to each Ru center is a PPh3 ligand in an equatorial position and a Cp ring in an
axial position. The compound is diamagnetic. The compound [Ru2Cp2(
conditions in the presence of air. This structure comprises a centrosymmetric Ru4Se6 dimer formed from the two
bridging Se groups and the two bridging Se2 groups. Each Ru center is -bonded to a Cp ring. The reaction of
solid [RuClCp(PPh3)2] with a Ten polytelluride solution in DMF leads to the diamagnetic compound [(RuCp-
(PPh3))2( 2-(1,4- :3,6- )Te6)] (3). Here the Ru centers are bound to a bridging Te6 chain at the 1, 4, 3, and 6
µ3-Se2)(µ3-Se)]2 (2) is obtained under similar
π
2-
µ
η
η
positions, leading to a bicyclic Ru2Te6 ring. Each Ru atom is bound to a Cp ring and a PPh3 group. This dimer
possesses a center of symmetry. The structure of 3 is the first example of a bicyclic complex where fusion occurs
along a Te−Te bond. If the same reaction is carried out in DMF/CH2Cl2, rather than DMF, then [(RuCp(PPh3))2-
(
µ
2-(1,4- :3,6-
η
η
)Te6)] CH2Cl2 (4) is obtained. In the solid state it possesses the same Ru2Te6 structural unit as
‚
does 3, but the unit lacks a crystallographically imposed center of symmetry. The electronic structures of 3 and 4
have been analyzed with the use of first principles density functional theory. Bond order analysis indicates that the
Te− −Te single bonds.
Te bond where fusion occurs has a shared bonding charge of about 2/3 of that found for Te
Introduction
development of an extensive polychalcogenometalate chem-
istry.14-19A number of different compounds of the type M(µ-
Qn)2M (where Q ) S, Se, Te; M ) metal) have been
synthesized and structurally characterized. The most common
of this type are M(µ-Q2)2M six-membered ring compounds
of Co,20 Ru,21,22 and Ti,23 and M(µ-Q3)2M eight-membered
Many polychalcogenide anions have been isolated and
structurally characterized by single-crystal diffraction
methods.1-13 These anions have been employed in the
* To whom correspondence should be addressed. E-mail:
ibers@chem.northwestern.edu.
† Department of Chemistry.
(9) Mu¨ller, V.; Ahle, A.; Frenzen, G.; Neumu¨ller, B.; Dehnicke, K.;
Fenske, D. Z. Anorg. Allg. Chem. 1993, 619, 1247-1256.
(10) Smith, D. M.; Ibers, J. A. Coord. Chem. ReV. 2000, 200-202, 187-
205.
‡ Department of Physics & Astronomy.
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943.
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Org. Chem. 1989, 44, 1397-1401.
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Chem. Sci. 1991, 46, 63-67.
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10.1021/ic0483646 CCC: $30.25
Published on Web 04/21/2005
© 2005 American Chemical Society
Inorganic Chemistry, Vol. 44, No. 10, 2005 3441

Dibrov et al.
ring compounds of Ti24 and Ru.25 Also known are the ten-
membered [Au(µ-S4)2Au]2- ring26 and the unsymmetrically
bridged compounds [(ReCp(CO))2(µ-S2)(µ-S3)]27 and [Re2-
(µ2-S)2(µ2-S3)2(S4)2]‚4H2O.28 A number of compounds with
the M(µ2-S2)(µ2-S)2M core have also been reported, where
M ) V,29,30 Fe,31-34 Ru,35 and Cr.36
Almost all such known chalcogen-bridged compounds are
sulfides. The Se-containing compounds [Re2O2Cp*2(µ2-Q)-
(µ2-Q2)] (Q ) S, Se)37 and [(Ti(MeCp)2)2(µ-Se2)2]38 are
known. Insofar as we know the only Te-containing com-
pound of this type is [(TiCp*2)2(µ-Te2)2].39 Here, we report
the syntheses and structural characterization of [RuCp(PPh3)-
(µ2-Se2)]2 (1), [Ru2Cp2(µ3-Se2)(µ3-Se)]2 (2), [(RuCp(PPh3))2-
(µ2-(1,4-η:3,6-η)Te6)] (3), and [(RuCp(PPh3))2(µ2-(1,4-η:3,6-
η)Te6)]‚CH2Cl2 (4). The compound [Ru(MeCp)(PPh3)(µ2-
Se2)]2[OTf]2 was characterized previously from its spectra,40
but no crystal structure was reported.
sieves. NMR data were recorded on a Mercury 400 MHZ
spectrometer. Elemental analyses were performed by Oneida
Research Services, Whitesboro, NY. Samples for NMR analyses
were washed with hexanes and then predried overnight under
vacuum at 70 °C.
Synthesis of [RuCp(PPh3)(µ2-Se2)]2 (1). Na2[TeSe3] (113 mg,
0.28 mmol) was dissolved in 5 mL of DMF. To this brown solution
100 mg (0.14 mmol) of solid [RuClCp(PPh3)2] was added. The
resulting solution was stirred under an N2 atmosphere for 3 h. It
was then filtered through a cannula. The resultant filtrate was
carefully layered with 10 mL of Et2O and sealed. In 5 days 26 mg
(32% yield) of [RuCp(PPh3)(µ2-Se2)]2 was obtained as green needle-
shaped crystals suitable for X-ray diffraction studies. For chemical
analysis, crystals of 1 were dissolved in CH2Cl2, the solution was
filtered through silica, and then 1 was precipitated by addition of
hexane. The resultant analysis is consistent with a hexane solvate.
Anal. Calcd for C46H40P2Ru2Se4‚C6H14: C 49.61; H 4.32. Found:
1
C 50.08; H 4.54. H NMR (CDCl3): δ 4.61 (s, 10 H), 7.23-7.26
(m, 30 H).
Synthesis of [Ru2Cp2(µ3-Se2)(µ3-Se)]2 (2). The same procedure
used to obtain 1 was followed except that the layered filtrate was
not sealed but rather was capped with a septum. In two weeks, in
addition to green crystals of compound 1, a few dark-brown X-ray
quality crystals of [Ru2Cp2(µ3-Se2)(µ3-Se)]2 (2) were isolated.
Experimental Section
General Procedures. All experiments were carried out under
an N2 atmosphere with the use of Schlenk-line techniques. Na2-
[TeSe3] and K2Te were synthesized by the reactions of stoichio-
metric quantities of the elements in liquid NH3. Te powder (Aldrich
Chemical Co., Milwaukee, WI), Se powder (Cerac, Inc., Milwaukee,
WI), and [RuClCp(PPh3)2] (Strem Chemicals, Inc., Newburyport,
ME) were used as received. CH2Cl2 (Fisher Chemicals, Inc., Fair
Lawn, NJ) was dried over P2O5; anhydrous Et2O (Fisher) was dried
over Na/benzophenone; and DMF (Fisher) was dried over molecular
Synthesis of [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)] (3). K2Te
(28 mg, 0.14 mmol) and Te (54 mg, 0.42 mmol) were stirred in 5
mL of DMF to give a purple solution. To this solution solid
[RuClCp(PPh3)2] (100 mg, 0.14 mmol) was added. The resulting
solution was stirred under an N2 atmosphere for 3 h. It was then
filtered through a cannula. The resultant filtrate was carefully
layered with 10 mL of Et2O and the filtrate flask was sealed. After
one week 55 mg, 0.034 mmol (49% yield) of [(RuCp(PPh3))2(µ2-
(1,4-η:3,6-η)Te6)] (3) was obtained as brown needle-shaped crystals
suitable for X-ray diffraction studies. Anal. Calcd for C46H40P2-
(20) Pleus, R. J.; Saak, W.; Pohl, S. Z. Anorg. Allg. Chem. 2001, 627,
250-253.
(21) Amarasekera, J.; Rauchfuss, T. B.; Rheingold, A. L. Inorg. Chem.
1987, 26, 2017-2018.
(22) Treichel, P. M.; Crane, R. A.; Haller, K. J. Polyhedron 1990, 9, 1893-
1
Ru2Te6: C, 34.05; H 2.48. Found: C, 33.16; H 2.64. H NMR
1899.
(23) Giolando, D. M.; Rauchfuss, T. B.; Rheingold, A. L.; Wilson, S. R.
Organometallics 1987, 6, 667-675.
(CDCl3): δ 4.48 (s, 10 H), 7.26-7.34 (m, 30 H).
Synthesis of [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)]‚CH2Cl2 (4).
K2Te (56 mg, 0.27 mmol) and Te (70 mg, 0.54 mmol) were stirred
in 5 mL of DMF to give a purple polytelluride solution. [RuClCp-
(PPh3)2] (70 mg, 0.10 mmol) was dissolved in 3 mL of CH2Cl2
and added dropwise to the polytelluride solution. The resulting
solution was stirred under N2 for 3 h and then filtered through a
cannula. The filtrate was layered with 10 mL of Et2O. After one
week 28 mg, 0.016 mmol (32% yield) of [(RuCp(PPh3))2(µ2-(1,4-
η:3,6-η)Te6)]‚CH2Cl2 (4), the CH2Cl2 solvate of compound 3, was
obtained as brown needle-shaped crystals suitable for X-ray
diffraction studies. Anal. Calcd for C47H42Cl2P2Ru2Te6: C, 33.06;
(24) Bolinger, C. M.; Rauchfuss, T. B.; Wilson, S. R. J. Am. Chem. Soc.
1981, 103, 5620-5621.
(25) Brunner, H.; Janietz, N.; Wachter, J.; Nuber, B.; Ziegler, M. L. J.
Organomet. Chem. 1988, 356, 85-91.
(26) Mu¨ller, A.; Ro¨mer, M.; Bo¨gge, H.; Krickemeyer, E.; Schmitz, K. Inorg.
Chim. Acta 1984, 85, L39-L41.
(27) Herberhold, M.; Reiner, D. Z. Naturforsch. B: Anorg. Chem. Org.
Chem. 1984, 39, 1199-1205.
(28) Mu¨ller, A.; Krickemeyer, E.; Wittneben, V.; Bo¨gge, H.; Lemke, M.
Angew. Chem., Int. Ed. Engl. 1991, 30, 1512-1514.
(29) Herberhold, M.; Kuhnlein, M. New J. Chem. 1988, 12, 357-359.
(30) Bolinger, C. M.; Rauchfuss, T. B.; Rheingold, A. L. J. Am. Chem.
Soc. 1983, 105, 6321-6323.
(31) Brunner, H.; Janietz, N.; Meier, W.; Sergeson, G.; Wachter, J.; Zahn,
T.; Ziegler, M. L. Angew. Chem., Int. Ed. Engl. 1985, 24, 1060-
1061.
1
H 2.48. Found: C, 32.72; H 2.37. H NMR (CDCl3): δ 4.48 (s,
10 H), 5.30 (s, 2H), 7.26-7.34 (m, 30 H).
(32) Weberg, R.; Haltiwanger, R. C.; DuBois, M. R. Organometallics 1985,
4, 1315-1318.
X-ray Structure Determinations. Single-crystal X-ray diffrac-
tion data were collected with the use of graphite-monochromatized
Mo KR radiation (λ ) 0.71073 Å) at 153 K on a Bruker Smart-
1000 CCD diffractometer.41 The crystal-to-detector distance was
5.023 cm. Crystal decay was monitored by recollecting 50 initial
frames at the end of data collection. Data were collected by a scan
of 0.3° in ω in four sets of 606 frames at æ settings of 0, 90, 180,
and 270°. The exposure times were 15 s/frame. The collection of
the intensity data was carried out with the program SMART.41 Cell
refinement and data reduction were carried out with the use of the
(33) Weberg, R. T.; Haltiwanger, R. C.; DuBois, M. R. New J. Chem. 1988,
12, 361-371.
(34) Yamada, M.; Tobita, H.; Inomata, S.; Ogino, H. Bull. Chem. Soc. Jpn.
1996, 69, 861-867.
(35) Rauchfuss, T. B.; Rodgers, D. P. S.; Wilson, S. R. J. Am. Chem. Soc.
1986, 108, 3114-3115.
(36) Goh, L. Y.; Mak, T. C. W. J. Chem. Soc., Chem. Commun. 1986,
1474-1475.
(37) Herberhold, M.; Jin, G.-X.; Milius, W. J. Organomet. Chem. 1993,
459, 257-263.
(38) Giolando, D. M.; Papavassiliou, M.; Pickardt, J.; Rauchfuss, T. B.;
Steudel, R. Inorg. Chem. 1988, 27, 2596-2600.
(39) Fenske, D.; Grissinger, A. Z. Naturforsch. B: Chem. Sci. 1990, 45b,
1309-1313.
(41) Bruker SMART Version 5.054 Data Collection and SAINT-Plus Version
6.45a Data Processing Software for the SMART System; Bruker
Analytical X-ray Instruments, Inc.: Madison, WI, 2003.
(40) Amarasekera, J.; Houser, E. J.; Rauchfuss, T. B.; Stern, C. L. Inorg.
Chem. 1992, 31, 1614-1620.
3442 Inorganic Chemistry, Vol. 44, No. 10, 2005

Characterization of Selenoruthenates and Telluroruthenates
Table 1. Selected Crystallographic Data for [RuCp(PPh3)(µ2-Se2)]2 (1), [Ru2Cp2(µ3-Se2)(µ3-Se)]2 (2), [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)] (3), and
[(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)]‚CH2Cl2 (4)
1
2
3
4
formula
formula weight
crystal system
space group
a (Å)
C46H40P2Ru2Se4
1172.7
triclinic
P1h
C20H20Ru4Se6
1138.4
monoclinic
C2/c
12.401(3)
13.607(3)
14.801(3)
90
C46H40P2Ru2Te6
1622.46
monoclinic
C2/c
25.211(2)
13.8374(12)
17.1079(15)
90
C47H42Cl2P2Ru2Te6
1707.39
triclinic
P1h
9.5419(14)
11.8807(17)
11.9229(18)
93.561(3)
93.604(3)
109.951(2)
1263.0(3)
153
9.3753(16)
14.520(2)
19.117(3)
81.536(3)
83.552(3)
74.870(3)
2477.5(7)
153
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V
110.628(3)
90
119.5060(10)
90
2337.5(8)
153
5194.2(8)
153
T (K)
Z
F
1
4
4
2
calc. (g cm-3
)
1.542
3.235
2.075
2.289
µ (Mo KR) (mm-1
)
3.57
11.886
0.0347
0.0860
3.975
4.277
R1(Fo) (Fo2 > 2σ(Fo ))a
0.0443
0.0426
0.0496
2
wR(Fo )b
0.1295
0.1022
0.1459
2
2
2
2
4
2
2
2
2
2
a R1(Fo) ) ∑||Fo| - |Fc||/∑|Fo|. b wR(Fo ) ) [∑w(Fo - Fc )2/∑wFo ]1/2; w-1 ) σ2(Fo ) + (qFo )2 for Fo > 0; w-1 ) σ2(Fo ) for Fo e 0; q ) 0.068
for 1; 0.038 for 2; 0.056 for 3; 0.087 for 4.
program SAINT41 and face-indexed absorption corrections were
performed numerically with the use of the program XPREP.42 Then
the program SADABS41 was employed to make incident beam and
decay corrections.
available. For all atoms a triple-ú Slater-type orbital (STO) basis
set augmented by one polarization function was employed. The
frozen core approximation was used to treat the core electrons. Bond
and valency indices were calculated according to the definitions
proposed by Mayer48,49 with a program50,51 designed for ADF output
files. The Xaim program52 was used to search bond critical points
according to the atoms-in-molecules theory of Bader.53
Two distinct types of charge distribution analyses were made:
by analytic Mulliken atomic orbital populations, and by Voronoi
volume charge analysis. The two analyses give a complementary
and reinforcing view of the electronic distribution. The traditional
Mulliken atomic population analysis of the occupied orbitals is
useful to extract effective atomic configurations, whereas the
volume charge analysis exploits a partition of the space associated
with each atom and an integration of the charge within each volume.
The Voronoi volume of an atom used in the present analyses is
defined as the region of space closest to that atom, being a
polyhedron defined by planes bisecting interatomic vectors. The
Mulliken method is more chemically intuitive, whereas the volume
charge analysis is more attuned to concepts of ionic and covalent
atomic radii. Neither of them is invariant to the choice of atomic
parameters, namely to atomic orbital basis sets and the geometric
definition of atomic volumes. However, the combination of the two
methods leads to considerable insight into charge distributions.
The structures were solved with the direct methods program
SHELXS and refined with the full-matrix least-squares program
SHELXL of the SHELXTL suite of programs.42 The positions of
the hydrogen atoms were idealized and constrained with the use of
a riding model. The final models involved anisotropic displacement
parameters for all non-hydrogen atoms. The solution and refinement
of the structures of 2 and 4 were straightforward. However, the
structures of compounds 1 and 3 both exhibited residual electron
density ascribable to solvent that could not be modeled satisfactorily.
Consequently, the program SQUEEZE43 of the PLATON program
suite was used to model these solvent regions. These amounted to
153 electrons per unit cell of compound 1, corresponding to about
four DMF molecules per Ru2Se4 unit, and 110 electrons per unit
cell of compound 3, corresponding to about three DMF molecules
per Ru2Te6 unit. The presence of these solvents is not taken into
account in the formulas of 1 or 3 or in the associated crystal data
of Table 1. In compound 1 one of the phenyl rings exhibits
displacement ellipsoids suggestive of some positional disorder.
Additional details may be found in the Supporting Information.
Electronic Structure Calculations. Calculations were performed
on compounds 3 and 4 with the use of first principles density
functional theory (DFT). For comparison, we also performed
calculations on the two S-analogues [(RuCp(P(OMe)3))2(µ2-S6)]22
and [(Ru(MeCp)(PPh3))2(µ2-S6)].21 Single-point energy calculations
with experimental geometries were performed; these were carried
out with the Amsterdam density functional program (ADF2003).44-46
The exchange-correlation potentials were treated in the local density
approximation (LDA) by means of the Vosko-Wilk-Nusair
(VWN) correlation scheme.47 The TZP numerical basis set was
used. It is of high quality, comparable to the best Gaussian bases
Results and Discussion
In an effort to synthesize mixed Te/Se polychalcogenom-
etalates we have chosen the [TeSe3]2- ligand as the precursor
owing to its use in the successful syntheses of the
[AuTeSe2]22- 54 and [(CpM(µ2-Se2))3(µ3-O)(µ3-TeSe3)]- (M
) Zr, Hf) anions.55
(47) Vosko, S. H.; Wilk, L.; Nusair, M. Can. J. Phys. 1980, 58, 1200-
1211.
(48) Mayer, I. Int. J. Quantum Chem. 1986, XXIX, 73-84.
(49) Mayer, I. Int. J. Quantum Chem. 1986, XXIX, 477-483.
(50) Bridgeman, A. J.; Empson, C. J. Mayer; The University of Hull: Hull,
U.K., 2003.
(42) Sheldrick, G. M. SHELXTL Version 6.14; Bruker Analytical X-ray
Instruments, Inc.: Madison, WI, 2003.
(43) van der Sluis, P.; Spek, A. L. Acta Crystallogr. Sect. A: Found.
Crystallogr. 1990, 46, 194-201.
(51) Bridgeman, A. J.; Cavigliasso, G.; Ireland, L. R.; Rothery, J. J. Chem.
Soc., Dalton Trans. 2001, 2095-2108.
(44) Te Velde, G.; Bickelhaupt, F. M.; Baerends, E. J.; Fonseca Guerra,
C.; Van Gisbergen, S. J. A.; Snijders, J. G.; Ziegler, T. J. Comput.
Chem. 2001, 22, 931-967.
(52) Alba, J. C. O.; Jane´, C. B. Xaim, Ver. 1.0; Departament de Qu´ımica
F´ısica i Inorga`nica, Universitat Rovira i Virgili: Pl. Tarragona, Spain,
1998.
(45) Baerends, E. J.; Ellis, D. E.; Ros, P. Chem. Phys. 1973, 2, 41-51.
(46) Guerra, C. F.; Snijders, J. G.; te Velde, G.; Baerends, E. J. Theor.
Chem. Acc. 1998, 99, 391-403.
(53) Bader, R. F. W. Atoms in Molecules: A Quantum Theory; Clarendon
Press: Oxford, 1990.
(54) Dibrov, S. M.; Ibers, J. A. Chem. Commun. 2003, 2158-2159.
Inorganic Chemistry, Vol. 44, No. 10, 2005 3443

Dibrov et al.
Table 2. Selected Bond Distances (Å) and Angles (deg) for [RuCp(PPh3)(µ2-Se2)]2 (1)
Ru(1)-P(1)
Ru(1)-Se(2)
Ru(1)-Se(1)
Se(1)-Se(2A)
Ru(1)-C
2.281(2)
2.4114(8)
2.4211(8)
2.3307(9)
2.228(6)-2.271(6)
1.831(6)-1.838(6)
1.353(11)-1.396(9)
C-C (Cp)
1.401(10)-1.423(9)
Se(2)-Ru(1)-Se(1)
Se(2A)-Se(1)-Ru(1)
Se(1A)-Se(2)-Ru(1)
Se(1)-Ru(1)-P(1)
Se(2)-Ru(1)-P(1)
Ru(1)-Se(2)-Se(1A)-Ru(1A)
102.67(3)
103.40(3)
107.83(3)
90.36(5)
89.45(5)
71.7
P(1)-C
C-C (Ph)
Table 3. Selected Bond Distances (Å) and Angles (deg) for [Ru2Cp2(µ3-Se2)(µ3-Se)]2 (2)
Ru(1)-Se(2)
2.3924(9)
2.4503(8)
2.4851(8)
2.8250(8)
2.4133(8)
2.4500(9)
2.4526(9)
2.3550(9)
2.218(6)-2.262(6)
2.184(7)-2.275(7)
1.403(11)-1.427(10)
98.70(3)
94.40(3)
73.95(3)
Se(1)-Ru(1)-Ru(2)
Se(1A)-Ru(2)-Se(3)
Se(1A)-Ru(2)-Se(2)
Se(3)-Ru(2)-Se(2)
Se(1A)-Ru(2)-Ru(1)
Se(3)-Ru(2)-Ru(1)
Se(2)-Ru(2)-Ru(1)
Se(1A)-Ru(1)-Ru(2)
Ru(2A)-Se(1)-Ru(1A)
Ru(2A)-Se(1)-Ru(1)
Ru(1A)-Se(1)-Ru(1)
Se(3A)-Se(2)-Ru(1)
Se(3A)-Se(2)-Ru(2)
Ru(1)-Se(2)-Ru(2)
Se(2A)-Se(3)-Ru(2)
107.46(3)
92.72(3)
98.07(3)
87.56(3)
55.10(2)
117.00(3)
53.35(2)
53.88(2)
71.01(2)
121.28(3)
105.46(3)
112.76(3)
119.87(3)
71.32(2)
111.19(3)
Ru(1)-Se(1A)
Ru(1)-Se(1)
Ru(1)-Ru(2)
Ru(2)-Se(1A)
Ru(2)-Se(3)
Ru(2)-Se(2)
Se(2)-Se(3A)
Ru(1)-C
Ru(2)-C
C-C
Se(2)-Ru(1)-Se(1A)
Se(2)-Ru(1)-Se(1)
Se(1A)-Ru(1)-Se(1)
Se(2)-Ru(1)-Ru(2)
55.33(2)
[RuCp(PPh3)(µ2-Se2)]2 (1). Reaction of Na2[TeSe3] with
[RuClCp(PPh3)2] in DMF followed by slow addition of Et2O
afforded green needles of [RuCp(PPh3)(µ2-Se2)]2 (1) in 32%
yield. Compound 1 could also be obtained in moderate yield
by the reaction of K2Se2 or K2Se3 with [RuClCp(PPh3)2]
under conditions similar to those described above. The MeCp
analogue of compound 1 has been reported, but with no
accompanying crystallographic information.40 The molecular
structure of [RuCp(PPh3)(µ2-Se2)]2 (1) is depicted in Figure
1 and selected bond distances and angles are summarized in
Table 2. In the structure, the two bridging Se2 groups lead
to a centrosymmetric Ru2Se4 six-membered core with a chair
conformation. The bulky PPh3 groups are in equatorial
positions and the smaller Cp ligands are in axial positions.
The Se-Se bond length is 2.3307(9) Å, typical for a single
bond. The Ru-P bond length of 2.281(2) Å is also a normal
single bond. All other bonds involving P or C are typical.
Figure 1. Structure of [RuCp(PPh3)(µ2-Se2)]2 (1).
21
Similar to its sulfur analogues [Ru(MeCp)(PPh3)(µ2-S2)]2
and [RuCp(P(OMe)3)(µ2-S2)]2,22 compound 1, [RuCp(PPh3)-
(µ2-Se2)]2, is diamagnetic and has a symmetric structure, as
evidenced by 1H NMR spectroscopy. Ru-S multiple bonding
was invoked to explain the diamagnetism of the sulfur
analogues.21,22 That Ru-Se multiple bonding occurs in
[RuCp(PPh3)(µ2-Se2)]2 is not clear from the Ru-Se bond
lengths of 2.4114(8) Å and 2.4211(8) Å because direct
comparisons with analogous compounds are lacking. How-
ever, in the compound [Ru2Cp2(µ3-Se2)(µ3-Se)]2 (2) described
below, the Ru-Se bond lengths are 2.3924(9) Å, 2.4503(8)
Figure 2. Structure of [Ru2Cp2(µ3-Se2)(µ3-Se)]2 (2).
if the system that led to the crystallization of 1 was capped
with a septum, rather than sealed. Presumably 2 results from
the exposure of the system to oxygen. Compound 2 was not
obtained in sufficient yield to enable chemical analyses or
spectroscopic studies to be performed. The structure of 2
contains a centrosymmetric Ru4Se6 cluster formed from the
two bridging Se groups and the two bridging Se2 groups.
Each Ru is π-bonded to a Cp ring (Figure 2). Selected bond
distances and angles are given in Table 3. There appear to
be no chalcogen/metal analogues of compound 2. It is an
Å, and 2.4851(8) Å; in [Ru(MeCp)(PPh3)(µ2-(1-η1:2-η2)-
2+ 40
Se2)]2
they are 2.473 (1) Å and 2.556(1) Å; and in
[{RuCl2(P(OMe)3)2}(µ2-Se2)(µ-Cl)2]256 they average 2.33 Å.
Ru-Se multiple bonding is not supported by the first
principles calculations described below.
[Ru2Cp2(µ3-Se2)(µ3-Se)]2 (2). A small amount of crystal-
line [Ru2Cp2(µ3-Se2)(µ3-Se)]2 (2) was obtained consistently
(55) Dibrov, S. M.; Ibers, J. A. C. R. Chimie 2005, in press.
(56) Mizutani, J.; Matsumoto, K. Chem. Lett. 2000, 29, 72-73.
3444 Inorganic Chemistry, Vol. 44, No. 10, 2005

Characterization of Selenoruthenates and Telluroruthenates
Table 4. Selected Bond Distances (Å) and Angles (deg) for [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)] (3)
Ru(1)-Te(1)
2.5940(6)
2.7975(6)
2.7228(6)
2.284(2)
2.195(7)-2.231(6)
93.37(2)
Ru(1)-Te(3A)
Te(1)-Te(1A)
Te(3)-Ru(1A)
P(1)-C
2.6458(6)
Te(1)-Te(2)
2.9493(8)
Te(2)-Te(3)
2.6458(6)
Ru(1)-P(1)
1.833(6)-1.849(6)
1.369(10)-1.405(9)
1.402(10)-1.421(9)
108.77(2)
Ru-C
C-C (Ph)
Te(1)-Ru(1)-Te(3A)
Ru(1)-Te(1)-Te(1A)
Te(3)-Te(2)-Te(1)
C-C (Cp)
108.43(2)
89.90(2)
Ru(1)-Te(1)-Te(2)
Te(2)-Te(1)-Te(1A)
Ru(1A)-Te(3)-Te(2)
94.96(2)
98.87(2)
Table 5. Selected Bond Distances and Angles for [(RuCp(PPh3))2(µ2-(1,4-η: 3,6-η)Te6)]‚CH2Cl2 (4)
Ru(1)-Te(4)
2.562(1)
Ru(1)-Te(1)
2.638(1)
Ru(2)-Te(3)
2.563(1)
Ru(2)-Te(6)
2.651(1)
Te(1)-Te(2)
2.716(1)
Te(2)-Te(3)
2.740(1)
Te(3)-Te(4)
3.046(1)
Te(4)-Te(5)
2.725(1)
Te(5)-Te(6)
2.706(1)
Ru(1)-P(1)
2.294(3)
Ru(2)-P(2)
2.284(3)
Ru(1)-C
2.20(1)-2.24(1)
1.35(2)-1.44(2)
96.62(3)
Ru(2)-C
2.20(1)-2.25(1)
1.83(1)-1.85(1)
94.90(4)
C-C (Ph and Cp)
Te(3)-Ru(2)-Te(6)
Te(1)-Te(2)-Te(3)
Ru(2)-Te(3)-Te(4)
Ru(1)-Te(4)-Te(5)
Te(5)-Te(4)-Te(3)
Ru(2)-Te(6)-Te(5)
P-C
Te(4)-Ru(1)-Te(1)
Ru(1)-Te(1)-Te(2)
Ru(2)-Te(3)-Te(2)
Te(2)-Te(3)-Te(4)
Ru(1)-Te(4)-Te(3)
Te(6)-Te(5)-Te(4)
91.71(3)
103.95(3)
104.95(3)
88.50(3)
111.48(3)
91.34(3)
109.06(3)
105.40(3)
90.44(3)
102.79(3)
electron-paired compound and therefore it should be dia-
magnetic. The two Ru(III) atoms in each pair are joined by
a normal 2.8250(8) Å single bond. The Ru-µ3-Se distance
of 2.4851(8) Å is longer than the Ru-µ3-Se2 distances of
2.3924(9) and 2.4503(8) Å. The Se-Se distance of 2.3550-
(9) Å is a normal single bond. Ru-C and C-C distances
are typical.
[(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)] (3) and [(RuCp-
(PPh3))2(µ2-(1,4-η:3,6-η)Te6)]‚CH2Cl2 (4). Because the
reaction of [RuClCp(PPh3)2] with Na2[TeSe3] afforded only
Se-containing products, the reaction of [RuClCp(PPh3)2] with
Na2Te under similar conditions was investigated. If DMF
was used as solvent then the compound [(RuCp(PPh3))2(µ2-
(1,4-η: 3,6-η)Te6)] (3) was obtained in 49% yield; if DMF/
CH2Cl2 was the solvent system, then [(RuCp(PPh3))2(µ2-(1,4-
η:3,6-η)Te6)]‚CH2Cl2 (4) was obtained in 32% yield. In
compound 3 (Figure 3) and its CH2Cl2 solvate (Figure 4)
the Ru centers are bound to a bridging Te6 chain at the 1, 4,
3, and 6 positions, leading to a bicyclic Ru2Te6 ring. The
rings in these two compounds are shown in Figure 5 and
additional metrical data are provided in Tables 4 and 5.
Insofar as we can determine there are no other examples of
a bicyclic complex where fusion occurs along a Te-Te bond.
In the closely related S-analogues [(RuCp(P(OMe)3))2(µ2-
S6)]22 and [(Ru(MeCp)(PPh3))2(µ2-S6)]21 the S-S bond
lengths at the ring fusion are 2.610(2) and 2.772(3) Å,
respectively. That these two lengths differ so much is perhaps
surprising and may point to the general ease of deformation
of the bicyclic ring depending on the environment. These
S-S bond lengths at the postulated ring fusion are around
0.5-0.6 Å longer than a normal single bond. Nevertheless,
S-S bonding was invoked in [(Ru(MeCp)(PPh3))2(µ2-S6)]21
to rationalize the diamagnetism of the compounds; it was
believed to be induced by multiple Ru-S bonding. Similarly,
a theoretical study57 of [(RuCp(P(OMe)3))2(µ2-S6)]22 sug-
gested delocalization of charge in the molecular LUMO that
Figure 3. Structure of [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)] (3).
Figure 4. Structure of [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)]‚CH2Cl2 (4).
involves multiple Ru-S bonding and antibonding character
between the S atoms in the ring. The present results support
the delocalization of charge on those Ru2S6 rings, but do
not agree with the multiple Ru-S bonding interpretations.
Compounds 3 and 4 are also diamagnetic, which has been
confirmed by spin-polarized calculations. For these com-
pounds the case for ring fusion is much stronger. At ring
fusion the Te-Te bond lengths are 2.9493(8) and 3.046(1)
Å, respectively. (Note that here also the length is sensitive
2-
to the environment.) In acyclic Ten species, Te-Te bond
lengths range from about 2.68 to about 2.86 Å.10 Thus, the
(57) Kanis, D. R. Ph.D. Thesis, University of Wisconsin-Madison. 1989.
Te-Te bond lengths at the ring fusion are perhaps 0.2 Å
Inorganic Chemistry, Vol. 44, No. 10, 2005 3445

Dibrov et al.
Table 6. Mulliken Atomic Charges and Volume-Integrated Charges
(e-) of [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)] (3)
group
Mulliken charge
Voronoi charge
Ru(1)
Te(1)
Te(2)
Te(3)
Ru2Te6
Cp
-0.05
0.09
0.55
0.35
-0.08
0.15
0.06
0.20
2.49
-0.94
-0.32
0.02
-0.30
PPh3
0.29
Table 7. Mulliken Atomic Charges and Volume-Integrated Charges
(e-) of [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)]‚CH2Cl2 (4)
group
Mulliken charge
Voronoi charge
Ru(1)
Ru(2)
Te(1)
-0.05
-0.08
0.04
-0.05
0.13
0.56
0.54
0.14
Te(2)
0.08
Te(3)
0.36
Te(4)
-0.02
-0.02
-0.00
-0.04
-0.27
-0.25
0.29
0.45
Te(5)
0.10
Te(6)
0.26
Ru2Te6
Cp(1)
Cp(2)
PPh3(1)
PPh3(2)
2.48
-0.88
-0.89
-0.36
-0.34
0.28
Table 8. Mulliken Atomic Charges and Volume-Integrated Charges
(e-) of [(Ru(MeCp)(PPh3))2(µ2-S6)]
Figure 5. Bond distances and bond orders of the bicyclic Ru2Te6 rings in
(a) [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)] (3) and (b) [(RuCp(PPh3))2(µ2-
(1,4-η:3,6-η)Te6)]‚CH2Cl2 (4).
group
Ru(1)
Mulliken charge
Voronoi charge
0.38
0.49
-0.09
0.01
-0.19
-0.19
-0.00
-0.19
0.22
0.93
0.95
-0.07
0.06
-0.21
-0.14
0.08
-0.01
1.59
Ru(2)
S(1)
S(2)
S(3)
S(4)
S(5)
S(6)
Ru2S6
MeCp(1)
MeCp(2)
PPh3 (2)
PPh3 (2)
-0.31
-0.28
0.20
-0.66
-0.72
-0.12
-0.11
0.17
Table 9. Mulliken Atomic Charges and Volume-Integrated Charges
(e-) of [(RuCp(P(OMe)3))2(µ2-S6)]
Group
Ru(1)
Mulliken charge
Voronoi charge
0.43
0.39
-0.18
0.02
-0.23
-0.16
0.04
-0.21
0.10
0.94
0.94
-0.08
0.03
-0.13
-0.01
0.04
-0.21
1.52
-0.64
-0.63
-0.67
-0.12
Ru(2)
S(1)
S(2)
S(3)
S(4)
S(5)
S(6)
Ru2S6
Cp(1)
Cp(2)
P(OMe)3 (1)
P(OMe)3 (2)
-0.27
-0.24
0.22
0.19
longer than a normal single bond. The Ru-Te bond lengths
range from 2.562(1) to 2.651(1) Å. Owing to the paucity of
other examples, it is difficult to argue from structural results
that these bonds indicate multiple bond character. Neverthe-
less, they are shorter than the Ru-Te bonds of 2.673(2) to
2.745(2) Å in the Te-Te-Ru-Te-Te fragments in
[PPh4]2[Ru6(Te2)7(CO)12]58 and [PPh4]2[Ru4(Te2)2(Te)2(TeMe)2-
(CO)8].59
Figure 6. Bond distances (from CSD-FORBUJ) and bond orders of the
Ru2S6 ring in (a) [(Ru(MeCp)(PPh3))2(µ2-S6)]21 and (b) [(RuCp(P(OMe)3))2-
(µ2-S6)].22
Charge Distributions. Tables 6 and 7 show the Mulliken
atomic charges and volume-integrated atomic charges for
Te6-containing compounds 3 and 4. According to the
Mulliken analysis, charges on the Ru and Te atoms are
(58) Huang, S.-P.; Kanatzidis, M. G. J. Am. Chem. Soc. 1992, 114, 5477-
5478.
(59) Das, B. K.; Kanatzidis, M. G. Inorg. Chem. 1995, 34, 1011-1012.
3446 Inorganic Chemistry, Vol. 44, No. 10, 2005

Characterization of Selenoruthenates and Telluroruthenates
Figure 7. Valence charge density contour map within Te(1)-Te(1A)-Te(3) plane in [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)] (3). Equal interval contours are
shown.
approximately zero, which results in a nearly neutral bicyclic
Ru2Te6 ring. The Mulliken charges on the Cp ligands are
also rather small, ranging from -0.25 to -0.30 e-. The
corresponding charge distributions for the S-analogues are
listed in Tables 8 and 9. The Mulliken charges on Cp or
MeCp ligands of the S-analogues range from -0.24 to -0.31
e-, which are comparable to those in compounds 3 and 4.
The Ru atoms of the Ru2S6 rings bear more positive charge
than those of the Ru2Te6 rings, because the electronegativity
of Te (2.01) is much less than that of S (2.44). To understand
better the spatial electronic charge distributions, the volume-
integrated charges were also calculated. Because the bound-
ary planes of Voronoi cells are defined to be halfway between
atoms without regard to atomic radii, the Voronoi analysis
often leads to charges that are not chemically intuitive and
that differ significantly from those obtained in the Mulliken
analysis. For example, the volume charges of Ru are 0.55
to 0.56 e- in the Te-compounds and 0.93 to 0.94 e- in the
S-compounds, tracking the trend in Mulliken charges (-0.05
to -0.08 e- with Te-compounds and 0.38 to 0.49 e- with
S-compounds). The Voronoi cells are too compact to
represent the anionic character of Te accurately; the Te
charges vary from +0.08 to +0.45 e-. The volume analysis
of the smaller S anion gives results more consistent with
the corresponding Mulliken charges. The volume charges
on the Ru2Te6 rings are 2.49 e- and 2.48 e- in compounds
3 and 4, respectively, versus those of 1.59 e- and 1.52 e-
on the Ru2S6 rings in the S-analogues.21,22 Thus, the compact
Voronoi cells for Te give an exaggerated cationic character
to the Ru2Te6 rings compared to the Ru2S6 rings, in
contradiction to the Mulliken analysis. Owing to the exclu-
sion of density from the Te Voronoi cells the volume charges
on the ligands in compound 3 and 4 are also larger than
those on the related ligands in the two S-analogues, in
disagreement with the Mulliken analysis.
states. After self-consistent field iterations, spin moments on
the Ru atoms tended to zero, which is consistent with their
observed diamagnetism.
Bond Analysis. Mayer bond order indices for Ru2Te6 in
compounds 3 and 4 are given in Figure 5. Bonding
interactions exist between the bridging Te atoms. Bond orders
are 0.44 e- for the Te(1)-Te(1A) bond in compound 3 and
0.30 e- for the Te(3)-Te(4) bond in compound 4, indicative
of significant shared bonding charge of about 2/3 of that found
for Te-Te single bonds. Bond orders for other bonds along
the Ru2Te6 rings range from 0.74 to 0.89 e-, indicative of
the absence of multiple bonding character. A plot of Te-Te
bond order (B) versus bond length (R) reveals a reasonably
linear correlation, with dB/dR about -1.73 e-/Å. No similar
correlation was found for Ru-Te bond order versus distance;
we presume this is because of the strong dependence of such
a correlation on angular Ru-Te bond distortions around the
metal site. Figure 6 shows the bond distances and bond orders
of the two Ru2S6 rings in the S-analogues. Bond orders for
the bridging S-S bonds are 0.25 and 0.28 e-, somewhat
smaller than those for the bridging Te-Te bonds. There is
no indication of multiple bonding interactions in the Ru2S6
rings, contrary to previous suggestions for (Ru(MeCp)-
(PPh3))2(µ2-S6).21 The bond orders for other bonds along the
Ru2S6 rings range from 0.74 to 1.12 e- for (Ru(MeCp)-
(PPh3))2(µ2-S6) and from 0.74 to 1.10 e- for (RuCp-
(P(OMe)3))2(µ2-S6). A plot of S-S bond order (B) versus
bond length (R) leads to a reasonably linear correlation, with
dB/dR about -1.19 e-/Å.
Figure 7 shows a contour map of the electron density
within the Te(1)-Te(1A)-Te(3) plane in compound 3. The
bond critical point between Te(1)-Te(1A) has two negative
curvatures and one positive curvature is therefore a (3, -1)
critical point.47 Other Ru-Te or Te-Te bonds on the Ru2-
Te6 rings are also (3, -1) critical points. The two negative
curvatures of (3, -1) critical points are perpendicular to the
bond path, where charge densities are local maxima. The
Spin polarized configurations of these four compounds
were found to be unstable, decaying to the spin-restricted
Inorganic Chemistry, Vol. 44, No. 10, 2005 3447

Dibrov et al.
2
Table 10. Selected Bond Properties at Bond Critical Points (∇F(rc) )
0)a, and Laplacian Curvature for [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)]
(3), and [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)]-CH2Cl2 (4)
∇ F increase with bond length in a nonlinear fashion. The F
values of Te-Te bond critical points are in the range of 0.041
to 0.061 e-/au3. The ∇ F values are all positive for Ru-Te
2
2
bond
bond distances (Å) F(rc)(e-/au3) ∇ F(rc)(e-/au5)
and Te-Te bonds, ranging from 0.05 to 0.15 e-/au.5
Therefore, their interactions are dominated by the attraction
of the charge density toward each of the interacting nuclei,
characteristic of “closed-shell interactions”.47 Ionic bonds are
a typical case of such interactions. Moreover, these critical
points for Ru-Te and Te-Te bonds have small F values
Compound 3
Te(1)-Te(1A)
Ru(1)-Te(1)
Te(1)-Te(2)
Te(2)-Te(3)
2.949
2.594
2.798
2.723
0.046
0.108
0.056
0.060
0.073
0.150
0.060
0.050
Compound 4
2
Te(3)-Te(4)
Ru(1)-Te(1)
Te(1)-Te(2)
Te(2)-Te(3)
3.046
2.638
2.716
2.740
0.041
0.105
0.061
0.061
0.073
0.125
0.056
0.059
and positive ∇ F values that are indicative of bonds with
ionic character. Nevertheless, in keeping with chemical
intuition the Te-Te interactions are manifestly covalent in
character, as deduced from the charge distributions.
a All critical points are (3, -1) bond critical points.47
positive curvature of a (3, -1) critical point is along the
bond path, where charge density is a minimum at the bond
critical point. The formation of a chemical bond is understood
as the resultant of two competing effects: the contraction
of the charge density toward the interatomic surface and the
contraction of the charge density toward each of the
interacting nuclei. For selected bond critical points Table 10
shows the charge density (F) and the Laplacian of the electron
density (∇ F), with the value of ∇ F being equal to the sum
of the three curvatures of the density at the bond critical
point. A plot of F values at Te-Te bond critical points versus
bond distances (R) reveals an excellent linear correlation,
with dF/dR about -0.033 e-/au.4 The Laplacian values of
Acknowledgment. This work was supported in part by
the U.S. National Science Foundation under grant CHE-
9819385. This work made use of Central Facilities supported
by the MRSEC program of the National Science Foundation
(DMR00-76097) at the Materials Research Center of North-
western University.
Supporting Information Available: Crystallographic data in
CIF format for [RuCp(PPh3)(µ2-Se2)]2 (1), [Ru2Cp2(µ3-Se2)(µ3-Se)]2
(2), [(RuCp(PPh3))2(µ2-(1,4-η:3,6-η)Te6)] (3), and [(RuCp(PPh3))2-
(µ2-(1,4-η:3,6-η)Te6)]‚CH2Cl2 (4). This material is available free
of charge via the Internet at http://pubs.acs.org.
2
2
IC0483646
3448 Inorganic Chemistry, Vol. 44, No. 10, 2005