Formation of (C5Me5)2U(EPh)Me, (C 5Me5)2U(EPh)2, and (C 5Me5)2U(η2-TeC6H 4) from (C5Me5)<s

Article abstract of DOI:10.1021/om700382a

(C₅Me₅)₂UMe₂, 1, reacts with 1 and 2 equiv of PhEEPh (E = S, Se) to form (C₅Me₅) ₂UMe(EPh) (E = S, 2; Se, 3) and (C₅Me₅)2U(EPh) ₂ (E = S, 4; Se,

Full text of DOI:10.1021/om700382a

Organometallics 2007, 26, 4287-4293
4287
Formation of (C5Me5)2U(EPh)Me, (C5Me5)2U(EPh)2, and
(C5Me5)2U(η2-TeC6H4) from (C5Me5)2UMe2 and PhEEPh
(E ) S, Se, Te)
William J. Evans,*,† Kevin A. Miller,† Joseph W. Ziller,† Antonio G. DiPasquale,‡
Katie J. Heroux,‡ and Arnold L. Rheingold‡
Department of Chemistry, UniVersity of California, IrVine, California 92697-2025, and Department of
Chemistry and Biochemistry, UniVersity of California, San Diego, 9500 Gilman DriVe, MC 0358,
La Jolla, California 92093-0358
ReceiVed April 19, 2007
(C5Me5)2UMe2, 1, reacts with 1 and 2 equiv of PhEEPh (E ) S, Se) to form (C5Me5)2UMe(EPh) (E
) S, 2; Se, 3) and (C5Me5)2U(EPh)2 (E ) S, 4; Se, 5), respectively, with concomitant formation of
MeEPh. Complexes 2, 3, and 5 form at ambient temperature, but the synthesis of 4 required heating to
65 °C. Addition of 2 equiv of PhTeTePh to 1 equiv of (C5Me5)2UMe2 generated the tellurium analogue
of 4 and 5, namely, (C5Me5)2U(TePh)2, 6, but when 1 was reacted with 1 equiv of PhTeTePh, C-H
activation of the aryl ring occurred to form (C5Me5)2U(η2-TeC6H4), 7, along with MeTePh and CH4.
Scheme 1
Introduction
Recent developments in actinide reduction chemistry have
shown that ligand-based reduction involving (C5Me5)-, (BPh4)-,
and H- anions can be combined with metal-based reduction to
accomplish multielectron reductions.1-3 Reductions involving
two,2 three,1 four,2,3 six,2,3 and eight3 electrons have been
observed depending on the substrate and the starting material.
Hence, in the formation of (C5Me5)2U(EPh)2 (E ) S,4 Se3) from
[(C5Me5)2UH]2 in Scheme 1, the two U3+ metal ions deliver
two electrons and the two H- ligands deliver two electrons and
form H2 in an overall four-electron process.3 The reduction in
Scheme 1 can also be accomplished with the tetravalent hydrides
[(C5Me5)2UH2]2 and [(C5Me5)2ThH2]2 in reactions that formally
involve only the hydride ions as the reductant,3 Scheme 2.
These results raised questions about what other ligands in
organometallic actinide complexes could accomplish reductions
of this type. (C5Me5)2UMe2, 1, was of interest because it is the
precursor to the hydrides above.5 If the same reduction done
by the hydride ligands could be done by the methyl ligands,
this would provide access to the reduction products with one
less step. Alkyllithium reagents are known to act as reductants
in certain cases,6 so it is not unreasonable to investigate alkyl
complexes of other electropositive metals in this regard. Since
the PhEEPh substrates constitute easily reducible test cases, their
reaction chemistry with (C5Me5)2UMe2, 1, was investigated. The
chalcogen substrates are also good because some of the
anticipated reduction products can be easily identified since they
are already in the literature.3,4
Experimental Section
The manipulations described below were performed under argon
with rigorous exclusion of air and water using Schlenk, vacuum
line, and glovebox techniques. Solvents were dried over Q-5 and
molecular sieves and saturated with argon using GlassContour7
columns. Benzene-d6 was dried over NaK alloy and vacuum
transferred before use. (C5Me5)2UMe2 was prepared as previously
described.5 PhSSPh, PhSeSePh, and PhTeTePh were purchased
from Aldrich and sublimed before use. NMR spectra were recorded
with a Bruker DRX 500 MHz system. Infrared spectra were
recorded as KBr pellets on a Varian 1000 FT-IR instrument.
Elemental analyses were performed by Analytische Laboratorien,
Lindlar, Germany. X-ray data collection parameters are given in
Table 1, and full crystallographic information is in the Supporting
Information.
(C5Me5)2UMe(SPh), 2. PhSSPh (75 mg, 0.34 mmol) in toluene
(5 mL) was added to a red solution of 1 (184 mg, 0.344 mmol) in
toluene (10 mL). After the mixture was stirred for 12 h, the dark
red solution was evaporated to dryness, yielding a red oil. The red
oil was dissolved in hexane and cooled to -35 °C. After 4 days, 2
was obtained as dark red crystals. The crystals were washed with
cold hexane (-35 °C) and dried under reduced pressure (148 mg,
68%). The hexane wash was dried under reduced pressure, yielding
a red oil that displayed additional resonances in the 1H NMR
* Corresponding author. Fax: 949-824-2210. E-mail: wevans@uci.edu.
† University of California, Irvine.
‡ University of California, San Diego.
(1) Evans, W. J.; Nyce, G. W.; Ziller, J. W. Angew. Chem., Int. Ed.
2000, 39, 240.
(2) Evans, W. J.; Kozimor, S. A.; Ziller, J. W. Chem. Commun. 2005,
4681.
(3) Evans, W. J.; Miller, K. A.; Kozimor, S. A.; Ziller, J. W.; DiPasquale,
A. G.; Rheingold, R. L. Organometallics 2007, 26, 3568.
(4) Lescop, C.; Arliguie, T.; Lance, M.; Nierlich, M.; Ephritikhine, M.
J. Organomet. Chem. 1999, 580, 137.
(5) Marks, T. J.; Fagan, P. J.; Manriquez, J. M.; Maatta, E. A.; Seyam,
A. M. J. Am. Chem. Soc. 1981, 103, 6650.
(6) McKinley, J.; Aponick, A.; Raber, J. C.; Fritz, C.; Montgomery, D.;
Wigal, C. T. J. Org. Chem. 1997, 62, 4874.
(7) For more information on drying systems, see www.glasscontour.com.
10.1021/om700382a CCC: $37.00 © 2007 American Chemical Society
Publication on Web 07/18/2007

4288 Organometallics, Vol. 26, No. 17, 2007
EVans et al.
Scheme 2
Table 1. X-ray Data Collection Parameters for (C5Me5)2UMe(SPh), 2, (C5Me5)2UMe(SePh), 3, (C5Me5)2U(TePh)2, 6, and
(C5Me5)2U(η2-TeC6H4), 7
empirical formula
no.
C27H38SU
2
C27H38SeU
3
C32H40Te2U
6
C26H34TeU
7
fw
632.66
155(2)
679.56
100(2)
monoclinic
P21/n
8.9090(15)
17.166(3)
16.484(3)
100.332(2)
2480.1(8)
4
917.87
100(2)
712.16
100(2)
monoclinic
P21/n
8.4434(13)
16.064(3)
17.729(3)
93.046(2)
2401.2(6)
4
temp (K)
cryst syst
space group
a (Å)
b (Å)
c (Å)
â (deg)
volume (Å3)
Z
orthorhombic
P212121
11.5327(19)
13.747(2)
31.942(5)
90
5064.3(14)
8
1.660
orthorhombic
P212121
10.1421(16)
15.659(2)
19.378(3)
90
3077.4(8)
4
1.981
F
calcd (Mg/m3)
1.820
8.023
0.0331
0.0794
1.970
7.959
0.0238
0.0621
µ (mm-1
)
6.503
7.150
R1 [I > 2.0σ(I)]a
0.0277
0.0559
0.005(5)
0.0385
0.0899
0.000(5)
wR2 (all data)a
absolute struct param
2
2
2
a Definitions: wR2 ) [∑[w(Fo - Fc )2]/∑[w(Fo )2] ]1/2, R1 ) ∑||Fo| - |Fc||/∑|Fo|.
spectrum in C6D6 that match those of MeSPh (Aldrich). 1H NMR:
δ 1.9 (s, 3H, Me), 6.9 (t, 1H, p-H), 7.0 (t, 2H, m-H), 7.1 (d, 2H,
o-H). Crystals of 2 suitable for X-ray diffraction were grown at
-35 °C from a concentrated hexane solution. 1H NMR (C6D6): δ
mg, 0.028 mmol) in C6D6. 1H NMR spectroscopy showed conver-
sion of starting material to MeSPh and a 2:3 ratio (by C5Me5
resonances) of the previously characterized 44 and 2, respectively,
after 3 days. The NMR tube was flame-sealed under vacuum and
heated at 65 °C. After 8 h, 1H NMR spectroscopy showed complete
conversion to 4.4
(C5Me5)2U(SPh)2,4 4, from (C5Me5)2UMe(SPh), 2. PhSSPh (9
mg, 0.04 mmol) in C6D6 was added to an NMR tube containing 2
(25 mg, 0.040 mmol) in C6D6. 1H NMR spectroscopy showed
MeSPh and partial conversion of 2 to 44 in a 1:1 ratio by C5Me5
resonances after 2 days. The NMR tube was flame-sealed and heated
at 65 °C. After 8 h, 1H NMR spectroscopy showed complete
conversion to 4.4
3
9.4 (s, 30H, C5Me5, ∆ν1/2 ) 11 Hz), -3.3 (t, 1H, JHH ) 8 Hz,
3
p-H), -4.6 (t, 2H, JHH ) 8 Hz, m-H), -41.0 (br s, 2H, o-H),
-120.9 (s, 3H, U-CH3). 13C NMR (C6D6): δ -25.8 (C5Me5), 102.0
(C5Me5), 120.1 (o-phenyl), 91.7 (m-phenyl), 124.6 (p-phenyl), 129.7
(ipso-phenyl), -59.6 (U-CH3). IR: 2968m, 2905vs, 2856s, 2726w,
2361w, 1578w, 1474m, 1435s, 1378s, 1102m, 1024m, 802w, 739m,
696m cm-1. Anal. Calcd for C33H43SU: C, 51.26; H, 6.05; S, 5.07;
U, 37.62. Found: C, 51.26 ; H, 6.11; S, 4.91; U, 37.75.
(C5Me5)2UMe(SePh), 3. As described for 2, 3 was obtained as
red crystals (169 mg, 62%) from PhSeSePh (126 mg, 0.404 mmol)
in toluene (8 mL) and 1 (217 mg, 0.405 mmol) in toluene (10 mL).
(C5Me5)2U(SePh)2, 5, from (C5Me5)2UMe2, 1. PhSeSePh (14
mg, 0.044 mmol) in C6D6 was added to an NMR tube containing
1
The hexane wash displayed additional resonances in the H NMR
1
1 (12 mg, 0.022 mmol) in C6D6. H NMR spectroscopy showed
spectrum in C6D6 consistent with MeSePh.8 1H NMR: δ 1.9 (s,
3H, Me), 6.9 (t, 2H, m-H), 7.0 (t, 1H, p-H), 7.3 (d, 2H, o-H).
Crystals of 3 suitable for X-ray diffraction were grown at -35 °C
quantitative conversion of starting material to the previously
characterized 53 and MeSePh8 after 8 h.
1
(C5Me5)2U(SePh)2, 5, from (C5Me5)2UMe(SePh), 3. PhSeSePh
from a concentrated hexane solution. H NMR (C6D6): δ 9.7 (s,
3
(8 mg, 0.025 mmol) in C6D6 was added to an NMR tube containing
30H, C5Me5, ∆ν1/2 ) 11 Hz), -2.2 (t, 1H, JHH ) 8 Hz, p-H),
1
-4.6 (t, 2H, 3JHH ) 8 Hz, m-H), -37.2 (br s, 2H, o-H), -117.2 (s,
3H, U-CH3). 13C NMR (C6D6): δ -26.9 (C5Me5), 104.4 (C5Me5),
128.3 (o-phenyl), 94.9 (m-phenyl), 124.1 (p-phenyl), 126.5 (ipso-
phenyl), -59.3 (U-CH3). IR: 3068w, 2979m, 2904s, 2854s, 1575m,
1471s, 1431s, 1379s, 1020s, 1101m, 1066m, 1020s, 905w, 803w,
740s, 696m, 666m cm-1. Anal. Calcd for C33H43SeU: C, 47.72;
H, 5.64; Se, 11.62; U, 35.03. Found: C, 47.69; H, 5.66; Se, 12.02;
U, 34.80.
3 (17 mg, 0.025 mmol) in C6D6. H NMR spectroscopy showed
quantitative conversion of starting material to the previously
characterized 53 and MeSePh8 after 4 h.
(C5Me5)2U(TePh)2, 6. PhTeTePh (222 mg, 0.542 mmol) in
toluene (3 mL) was added to a red solution of 1 (145 mg, 0.271
mmol) in toluene (10 mL). After the mixture was stirred for 12 h,
the dark orange solution was evaporated to dryness, yielding a red
oil. The red oil was dissolved in hexane (2 mL) and cooled to -35
°C. After 1 day, 6 was obtained as red crystals. The crystals were
washed with cold hexane (-35 °C) and dried under reduced
pressure (115 mg, 46%). The hexane wash was dried under reduced
pressure, yielding a red oil that displayed additional resonances in
(C5Me5)2U(SPh)2, 4, from (C5Me5)2UMe2, 1. PhSSPh (12 mg,
0.055 mmol) in C6D6 was added to an NMR tube containing 1 (15
(8) Detty, M. R.; Wood, G. P. J. Org. Chem. 1980, 45, 80.

Formation of (C5Me5)2U(EPh)Me (E ) S, Se, Te)
Organometallics, Vol. 26, No. 17, 2007 4289
the 1H NMR spectrum in C6D6 consistent with MeTePh.9 1H NMR
(C6D6): δ 1.8 (s, 3H, Me), 6.9 (t, 2H, m-H), 7.0 (t, 1H, p-H), 7.5
(d, 2H, o-H). Crystals of 6 suitable for X-ray diffraction were grown
at -35 °C from a concentrated hexane solution. 1H NMR (C6D6):
molecules of the formula unit present (Z ) 8). Some of the methyl
carbon atoms associated with the pentamethylcyclopentadienyl
ligand defined by C(28)-C(37) exhibited higher than expected
thermal motion. Refinement of a disordered model with these atoms
included using multiple components, and partial site-occupancy
factors yielded no appreciable improvement. The absolute structure
was assigned by refinement of the Flack parameter,15 0.005(5).
X-ray Data Collection, Structure Solution, and Refinement
of 3. A red block 0.10 × 0.07 × 0.02 mm in size was mounted on
a Cryoloop with Paratone oil. Data were collected in a nitrogen
gas stream at 100(2) K using φ and ω scans. The crystal-to-detector
distance was 60 mm and exposure time was 10 s per frame using
a scan width of 0.3°. Data collection was 100.0% complete to 25.00°
in θ. A total of 20 628 reflections were collected covering the
indices -11 e h e 11, -22 e k e 22, -21 e l e 21; 5718
reflections were found to be symmetry-independent, with an Rint
of 0.0342. Indexing and unit cell refinement indicated a primitive,
monoclinic lattice. The space group was found to be P21/n (No.
14). The data were integrated using the Bruker SAINT11 software
program and scaled using the SADABS12 software program.
Solution by direct methods (SIR-2004) produced a complete heavy-
atom phasing model consistent with the proposed structure. All non-
hydrogen atoms were refined anisotropically by full-matrix least-
squares (SHELXL-97). All hydrogen atoms were placed using a
riding model. Their positions were constrained relative to their
parent atom using the appropriate HFIX command in SHELXL-
97.
3
δ 15.1 (s, 30H, C5Me5, ∆ν1/2 ) 18 Hz), 3.9 (t, 2H, JHH ) 8 Hz,
3
p-H), 1.8 (d, 4H, JHH ) 8 Hz, m-H), -26.1 (br s, 4H, o-H). 13C
NMR (C6D6): δ -27.7 (C5Me5), 127.6 (C5Me5), 108.6 (o-phenyl),
178.6 (m-phenyl), 133.9 (p-phenyl), 137.3 (ipso-phenyl). IR:
3048w, 2966s, 2900vs, 2727w, 1570vs, 1470vs, 1447m, 1431s,
1379m, 1060s, 1016w, 727s, 691s, 651m cm-1. Anal. Calcd for
C32H40Te2U: C, 41.87; H, 4.39; Te, 27.80; U, 25.93. Found: C,
42.07; H, 4.52; Te, 27.5; U, 26.3.
(C5Me5)2U(η2-TeC6H4), 7. PhTeTePh (82 mg, 0.200 mmol) in
toluene (5 mL) was added to a red solution of 1 (107 mg, 0.200
mmol) in toluene (10 mL). After the mixture was stirred for 12 h,
the dark brown solution was evaporated to dryness, yielding a brown
oil. The brown oil was dissolved in hexane (2 mL) and cooled to
-35 °C. After 1 day, 7 was obtained as brown crystals. The crystals
were washed with cold hexane (-35 °C) and dried under reduced
pressure (83 mg, 58%). As described above, the hexane wash was
dried under reduced pressure, yielding a red oil that displayed
additional resonances in the 1H NMR spectrum in C6D6 consistent
with MeTePh.9 Crystals of 7 suitable for X-ray diffraction were
1
grown at -35 °C from a concentrated hexane solution. H NMR
(C6D6): δ 5.9 (s, 30H, C5Me5, ∆ν1/2 ) 15 Hz), 4.1 (t, 1H, 3JHH
)
10 Hz, TeC6H4), -5.5 (t, 1H, 3JHH ) 8 Hz, TeC6H4), -5.9 (d, 1H,
3
3JHH ) 10 Hz, TeC6H4), -35.9 (d, 1H, JHH ) 10 Hz, TeC6H4).
13C NMR (C6D6): δ -35.5 (C5Me5), 113.3 (C5Me5), -17.0, 57.9,
138.7 152.2, 179.0, 185.3 (TeC6H4). IR: 3067w, 3035w, 3017w,
2973s, 2897vs, 2854s, 2724w, 1572w, 1548m, 1484w, 1445s,
1432s, 1390s, 1377vs, 1237s, 1095w, 1018m, 998m, 978m, 801w,
737vs, 692w, 651w, 626w cm-1. Anal. Calcd for C26H34TeU: C,
43.85; H, 4.81; Te, 17.92; U, 33.42. Found: C, 43.91; H, 4.96; Te,
17.7; U, 33.6.
X-ray Data Collection, Structure Solution, and Refinement
of 6. A red block 0.22 × 0.22 × 0.08 mm in size was handled as
described for 3. A total of 25,298 reflections were collected covering
the indices -12 e h e 13, -20 e k e 20, -25 e l e 25; 7135
reflections were found to be symmetry-independent, with an Rint
of 0.0581. Indexing and unit cell refinement indicated an ortho-
rhombic lattice. The space group was found to be P212121. The
absolute structure was assigned by refinement of the Flack
parameter,15 0.000(5). The data were handled as described for 3.
X-ray Data Collection, Structure Solution, and Refinement
of 7. A red crystal 0.30 × 0.30 × 0.24 mm in size was handled as
described for 3. A total of 18 903 reflections were collected covering
the indices -10 e h e 10, -20 e k e 20, -22 e l e 22; 5491
reflections were found to be symmetry-independent, with an Rint
of 0.0265. Indexing and unit cell refinement indicated a monoclinic
lattice. The space group was found to be P21/n. The data were
handled as described for 3.
A similar reaction was carried out with PhTeTePh (20 mg, 0.049
mmol) and 1 (26 mg, 0.049 mmol) in C6D6 in a sealed J-Young
1
tube. The reaction was followed by H NMR spectroscopy. After
20 min, the 1H NMR spectra showed complete conversion of
starting materials to new products displaying resonances consistent
1
with MeTePh9 and (C5Me5)2UMe(TePh). H NMR (C6D6): δ 9.8
(s, 30H, C5Me5), -0.2 (t, 1H, p-H), -2.5 (t, 2H, m-H), -29.9 (br
s, 2H, o-H), -118.2 (s, 3H, Me). After 16 h the spectrum contained
7 and a resonance at 0.13 ppm consistent with CH4.
X-ray Data Collection, Structure Solution, and Refinement
of 2. A red crystal of approximate dimensions 0.06 × 0.26 × 0.28
mm was mounted on a glass fiber and transferred to a Bruker CCD
platform diffractometer. The SMART10 program package was used
to determine the unit-cell parameters and for data collection (25
s/frame scan time for a sphere of diffraction data). The raw frame
data were processed using SAINT11 and SADABS12 to yield the
reflection data file. Subsequent calculations were carried out using
the SHELXTL13 program. The diffraction symmetry was mmm, and
the systematic absences were consistent with the orthorhombic space
group P212121, which was later determined to be correct. The
structure was solved by direct methods and refined on F2 by full-
matrix least-squares techniques. The analytical scattering factors14
for neutral atoms were used throughout the analysis. Hydrogen
atoms were included using a riding model. There were two
Results
Reaction Chemistry. (C5Me5)2UMe(EPh) (E ) S, 2; Se,
3). One equivalent of (C5Me5)2UMe2 reacts with 1 equiv of
PhEEPh (E ) S, Se) over 12 h to form (C5Me5)2UMe(EPh) (E
) S, 2; Se, 3) and MeEPh, eq 1. Separation of the byproduct,
(9) Hope, E. G.; Kemmitt, T.; Levason, W. Organometallics 1988, 7,
78.
(10) SMART Software Users Guide, Version 5.1; Bruker Analytical
X-Ray Systems, Inc.: Madison, WI, 1999.
(11) SAINT Software Users Guide, Version 6.0; Bruker Analytical X-Ray
Systems, Inc.: Madison, WI, 1999.
(12) Sheldrick, G. M. SADABS, Version 2.10; Bruker Analytical X-Ray
Systems, Inc.: Madison, WI, 2002.
(13) Sheldrick, G. M. SHELXTL, Version 6.12; Bruker Analytical X-Ray
Systems, Inc.: Madison, WI, 2001.

4290 Organometallics, Vol. 26, No. 17, 2007
EVans et al.
Figure 1. Molecular structure of (C5Me5)2UMe(SePh), 3, with
thermal ellipsoids drawn at the 50% probability level. (C5Me5)2-
UMe(SPh), 2, has the same structure.
Figure 2. Molecular structure of (C5Me5)2U(TePh)2, 6, with
thermal ellipsoids drawn at the 50% probability level.
MeEPh, from 2 and 3 was accomplished by washing crystals
of 2 and 3, obtained at -35 °C in hexane, with cold hexane
the reaction of (C5Me5)2UMe(SPh) and PhSSPh was required
in order to achieve complete conversion to (C5Me5)2U(SPh)2,4
Scheme 3.
1
(-35 °C). The hexane wash displayed H NMR resonances
consistent with MeEPh (E ) S, Se8). Complexes 2 and 3 were
(C5Me5)2U(TePh)2, 6, and (C5Me5)2U(η2-TeC6H4), 7. (C5-
Me5)2UMe2 reacts with 2 equiv PhTeTePh to form (C5Me5)2U-
(TePh)2, 6, in a reaction analogous to the formation of 5 from
1, Scheme 3. A byproduct was separated as described for the
sulfur and selenium analogues that displayed resonances in its
1H NMR spectrum consistent with MeTePh.9 The identity of
(C5Me5)2U(TePh)2, 6, was confirmed by X-ray crystallography,
Figure 2.
1
characterized by H and 13C NMR spectroscopy, IR spectros-
copy, and elemental analysis and were completely identified
by X-ray crystallography, Figure 1.
(C5Me5)2U(EPh)2 (E ) S, 4; Se, 5). When 1 equiv of (C5-
Me5)2UMe2 was reacted with 2 equiv of PhSeSePh, the
previously characterized complex (C5Me5)2U(SePh)2,3 5, was
formed along with MeSePh after 8 h. However, when (C5Me5)2-
UMe2 was reacted with 2 equiv of PhSSPh at room temperature
over a period of 3 days, complete conversion of starting material
to (C5Me5)2U(SPh)2, 4, a complex previously reported by
However, when (C5Me5)2UMe2, 1, was treated with 1 equiv
of PhTeTePh, the expected product, (C5Me5)2UMe(TePh),
analogous to 2 and 3, was not isolated. Instead, C-H activation
of the aryl ring occurred to form (C5Me5)2U(η2-TeC6H4), 7, CH4,
1
Ephritikhine et al.,4 did not occur. Instead, H NMR spectros-
1
copy revealed that both (C5Me5)2UMe(SPh), 2, and (C5Me5)2U-
(SPh)2,4 4, were present in a 3:2 ratio, respectively. After heating
the mixture at 65 °C for 8 h, complete conversion to 44 was
and MeTePh, Scheme 4. Complex 7 was characterized by H
and 13C NMR spectroscopy, IR spectroscopy, and elemental
analysis and was completely identified by X-ray crystallography,
Figure 3.
1
observed by H NMR spectroscopy.
(C5Me5)2U(EPh)2 (E ) S,4 Se3) can also be formed in a
stepwise manner from (C5Me5)2UMe(EPh) (E ) S, Se) with 1
equiv of PhEEPh (E ) S, Se), respectively. However, heating
When the reaction of 1 with 1 equiv of PhTeTePh was
monitored by 1H NMR spectroscopy, an intermediate that
1
displayed H NMR resonances consistent with (C5Me5)2UMe-
Scheme 3

Formation of (C5Me5)2U(EPh)Me (E ) S, Se, Te)
Organometallics, Vol. 26, No. 17, 2007 4291
Scheme 4
(TePh) was observed, but (C5Me5)2U(η2-TeC6H4), 7, CH4, and
MeTePh were the only products after 16 h. Hence, in this
tellurium system, the (C5Me5)2UMe(TePh) intermediate can
react in two ways. In the presence of PhTeTePh, complex 6 is
formed in competition with the metalation reaction to form 7.
Since 6 is formed in high yield, the aryl metalation reaction to
form 7 appears to be slow compared to the reaction with
PhTeTePh to make 6.
Table 2. Selected Bond Distances (Å) and Angles (deg) for
(C5Me5)2UMe(SPh), 2,a and (C5Me5)2UMe(SePh), 3
2
3
E ) S
E ) Se
U(1)-E(1)
2.7060(14)
2.8432(7)
U(2)-E(2)
2.7101(14)
2.427(5)
2.400(5)
1.772(5)
1.763(6)
2.463
2.459
2.463
2.455
2.713(4)-2.757(5) 2.716(5)-2.762(5)
2.74(1)
2.685(6)-2.769(5)
2.73(2)
U1-C(21): U(1)-C(27)
U(2)-C(48)
2.438(5)
1.920(5)
E(1)-C(22): E(1)-C(21)
E(2)-C(49)
U(1)-Cnt1
2.452
2.459
U(1)-Cnt2
U(2)-Cnt3
U(2)-Cnt4
U(1)-C(C5Me5) range
U(1)-C(C5Me5) average
U(2)-C(C5Me5) range
U(2)-C(C5Me5) average
2.73(1)
C(21)-U(1)-E(1): C(27)-U(1)-E(1) 102.87(14)
C(48)-U(2)-E(2) 98.21(14)
U(1)-E(1)-C(22): U(1)-E(1)-C(21) 105.77(16)
U(2)-E(2)-C(49) 110.45(19)
98.11(13)
104.79(15)
a Complex 2 has two crystallographically independent molecules in the
unit cell.
complex [Na(18-crown-6][(C8H8)U(C4H4S4)2].18 These are shorter
than the U-S(bridging ligand) distances of 2.806(3)-2.894(3)
Å in [(C8H8)U(µ-SCHMe2)]219 as expected. The U-S distance
in 2 is also 0.04 Å shorter than the analogue in (C5Me5)2Th-
(SPh)2.3 This is consistent with the 0.05 Å difference in the
Figure 3. Molecular structure of (C5Me5)2U(η2-TeC6H4), 7, with
Shannon ionic radii of eight-coordinate U4+ and Th4+ 20
The
.
thermal ellipsoids drawn at the 50% probability level.
U-S distance in 2 is shorter than the 2.777(1)-2.791(1) Å U-S
distances in trivalent [(C5Me5)2U(SiPr)2]-.21
Structure. The X-ray crystal structures of 2, 3, 6, and 7
display conventional metallocene metrical parameters for eight-
coordinate tetravalent uranium complexes of this type, Tables
1-3. The U-C(C5Me5) average distances of 2.74(2), 2.73(1),
2.72(3), and 2.73(3) Å for 2, 3, 6, and 7, respectively, are within
the broad range of 2.71(2) to 2.80(5) Å observed for eight-
coordinate tetravalent uranium metallocenes.16
The 2.708(2) Å U-S distance in 2 is equivalent to the 2.695-
(4) Å U-S(terminal ligand) distance in (C5Me5)3U(SMe)17 and
the 2.687(2)-2.700(2) Å U-S distances in the bis(dithiolene)
Fewer U-Se distances are available for comparison with 3.
In contrast to the over 100 crystallographically characterized
U-S complexes in the Cambridge Crystallographic Data Base,
only four22-24 crystallographically characterized U-Se com-
plexes are reported. None of these are metallocenes that allow
for direct comparison. However, the 2.8432(7) Å U-Se distance
in 3 is 0.14 Å longer than the 2.708(2) Å U-S distance in 2,
(18) Arliguie, T.; Fourmigue´, M.; Ephritikhine, M. Organometallics 2000,
19, 109.
(19) Leverd, P. C.; Arliguie, T.; Lance, M.; Nierlich, M.; Vigner, J.;
Ephritikhine, M. J. Chem. Soc., Dalton Trans. 1994, 501.
(20) Shannon, R. D. Acta Crystallogr. 1976, A23, 751.
(21) Arliguie, T.; Lescop, C.; Ventelon, L.; Leverd, P. C.; Thue´ry, P.;
Nielrich, M.; Ephritikhine, M. Organometallics 2001, 20, 3698.
(22) Gaunt, A. J.; Scott, B. L.; Neu, M. P. Chem. Commun. 2005, 3215.
(23) Zarli, B.; Graziani, R. J. Chem. Soc. D 1971, 1501.
(24) Gaunt, A. J.; Scott, B. L.; Neu, M. P. Inorg. Chem. 2006, 45, 7401.
(14) International Tables for X-Ray Crystallography; Kluwer Academic
Publishers: Dordrecht, 1992; Vol. C.
(15) Flack, H. D. Acta Crystallogr. 1983, A39, 876-881.
(16) Evans, W. J.; Miller, K. A.; Ziller, J. W.; Greaves, J. Inorg. Chem.,
in press.
(17) Leverd, P. C.; Ephritikhine, M.; Lance, M.; Vigner, J.; Nierlich,
M. J. Organomet. Chem. 1996, 507, 229.

4292 Organometallics, Vol. 26, No. 17, 2007
EVans et al.
Table 3. Selected Bond Distances (Å) and Angles (deg) for (C5Me5)2U(TePh)2, 6, and (C5Me5)2U(η2-TeC6H4), 7
6
7
U(1)-Te(1)
3.0383(6)
3.0504(6)
2.458
U(1)-Te(1)
2.9648(4)
2.352(4)
2.439
U(1)-Te(2)
U(1)-C(1)
U(1)-Cnt1
U(1)-Cnt1
U(1)-Cnt2
2.450
U(1)-Cnt2
2.447
Te(1)-C(21)
2.117(8)
2.125(8)
96.53
118.84
111.06
Te(1)-C(6)
2.195(4)
1.396(5)
109.47
109.85
101.56
Te(2)-C(27)
C(6)-C(1)
Cnt1-U(1)-Te(1)
Cnt1-U(1)-Te(2)
Cnt2-U(1)-Te(1)
Cnt2-U(1)-Te(2)
Cnt1-U(1)-Cnt2
C(21)-Te(1)-U(1)
C(27)-Te(2)-U(1)
Te(1)-U(1)-Te(2)
U(1)-C(C5Me5) range
U(1)-C(C5Me5) average
Cnt1-U(1)-Te(1)
Cnt2-U(1)-Te(1)
Cnt1-U(1)-C1(1)
Cnt2-U(1)-C(1)
Cnt1-U(1)-Cnt2
C(6)-Te(1)-U(1)
Te(1)-C(6)-C(1)
C(6)-C(1)-U(1)
Te(1)-U(1)-C(1)
U(1)-C(C5Me5) range
U(1)-C(C5Me5) average
97.37
134.58
102.64
138.34
109.7(2)
109.69(18)
101.848(19)
2.682(7)-2.780(8)
2.72(3)
65.73(10)
124.1(3)
96.8(2)
72.80(1)
2.781(3)-2.6879(4)
2.73(3)
which is in agreement with the 0.14 Å difference in the Shannon
ionic radii of S2- and Se2- 20
The 2.8432(7) Å U-Se distance
close to the range previously observed for uranium-aryl bonds,
2.386(3) to 2.561(13) Å.30,31
.
in 3 is similar to the 2.8004(7) Å average U-Se distance in
The four-membered U-Te-C(6)-C(1) ring in 7 is roughly
planar, with U(1) deviating from the Te-C(6)-C(1) plane by
0.3342 Å. This is similar to the situation in the (C5Me5)2MR-
(η2-ONC5H4) (M ) U, Th; R ) CH3, CH2Ph)30 complexes
involving a metalated pyridine ring, where uranium is 0.0698
Å and thorium is 0.0770 Å out of the O-N-C plane.
(C5Me5)2U(SePh)2.3
There are even fewer crystallographically characterized U-Te
complexes for comparison with 6 and 7. The only example of
a crystallographically characterized U-Te complex in the
literature, U{N(TePiPr2)2}3,25 reported by Neu and co-workers,
has a 3.16(3) Å U-Te distance. The 3.044(6) Å average U-Te
distance in 6 is 0.12 Å shorter, but the coordination environment
is quite different. The U-Te distance in 6 is also 0.24 Å longer
than the average U-Se distance in 5, which is in agreement
with the 0.23 Å difference in Shannon ionic radii of Te2- and
Discussion
The purpose of this study was to determine if (C5Me5)2UMe2,
1, would react with PhEEPh reagents to make the same (C5-
Me5)2U(EPh)2 products, 5 (E ) S) and 6 (E ) Se), formed by
[(C5Me5)2UH]2 in Scheme 1 and [(C5Me5)2UH2]2 in Scheme 2.
Complexes 5 and 6 are formed from 1, but the mechanisms of
the reactions are apparently very different from the hydride
reactions. The methyl groups in 1 do not act like the hydride
ligands in Schemes 1 and 2, which formally provide one electron
per hydride and eliminate dihydrogen. If the methyl group
provided an electron and formed methyl radicals, ethane or
methane would be the expected products. Instead, MeEPh is
observed as the byproduct. The MeEPh byproduct could be
formed by a σ-bond metathesis mechanism involving U-Me
and E-E bonds, eq 2. This type of reaction was previously
observed in the reaction of [(tBuC5H4)2Ln(µ-Me)]2 (Ln ) Y,
Lu) with REER (E ) S, Se; R ) Ph, nBu, tBuCH2Ph) that forms
MeER and [(tBuC5H4)2Ln(µ-ER)]2.32
Se2- 20
The 2.747(2) Å average Th-S distance in (C5Me5)2-
.
Th(SPh)23 is 0.30 Å shorter than the average U-Te distance in
6. This is in agreement with the expected 0.37 Å difference in
Shannon ionic radii of Te2- and S2- 20 and the 0.05 Å difference
in the ionic radii of eight-coordinate U4+ and Th4+ 20
The
.
2.9648(4) Å U-Te distance in 7 is 0.11 Å shorter than the
U-Te distance in 6. This may be due to the chelating nature of
the (TeC6H4)2- ligand.
The U-E-C(ipso) angles in 2 and 3 decrease from S to Se
with values of 105.77(16)° and 110.45(19)° for 2, which has
two crystallographically independent molecules in the unit cell,
and 104.79(15)° for 3. The decrease in angle from 2 to 3 is
similar to that in the solvated samarium benzene chalcogenolate
series, (C5Me5)2Sm(EPh)THF (E ) S, Se, Te).26 In this series,
the U-E-C(ipso) angles for S, Se, and Te complexes are
120.82(17)°, 118.51(14)°, and 112.49(6)°, respectively. The
109.70(5)° average U-Te-C(ipso) angle in (C5Me5)2U(TePh)2,
6, is 3° smaller than the 113(1)° U-Se-C(ipso) angle in 5,
which follows the trend that was observed for the U-E-C(ipso)
angles in 2, 3, and (C5Me5)2Sm(EPh)THF.26
The U-C(Me) distances, 2.41(1) Å for 2 and 2.438(7) Å for
3, are similar to U-C(Me) distances in (C5Me5)2UMe2,27,28
2.424(7) and 2.414(7) Å, (C5Me4H)2UMe2,29 2.426(2) Å, and
(C5Me4H)2UMeCl,29 2.38(2) Å. The 2.352(4) Å U-C(1)
distance in 7 is shorter than these U-C(Me) distances, but again
this may be due to the chelation of the ligand. However, this is
(25) Gaunt, A. J.; Scott, B. L.; Neu, M. P. Angew. Chem. 2006, 45, 1638.
(26) Evans, W. J.; Miller, K. A.; Lee, D. S.; Ziller, J. W. Inorg. Chem.
2005, 44, 4326.
(27) Barnea, E.; Andrea, T.; Kapon, M.; Berthet, J.-C.; Ephritikhine, M.;
Eisen, M. S. J. Am. Chem. Soc. 2004, 126, 10860.
(28) Jantunen, K. C.; Burns, C. J.; Castro-Rodriquez, I.; Da Re, R. E.;
Golden, J. T.; Morris, D. E.; Scott, B. L.; Taw, F. L.; Kiplinger, J. L.
Organometallics 2004, 23, 4682.
(29) Evans, W. J.; Kozimor, S. A.; Hillman, W. R.; Ziller, J. W.
Organometallics 2005, 24, 4676.
In the case of (C5Me5)2UMe2, the formation of 5 and 6 can
be effected stepwise by controlling the stoichiometry. Hence,
reactions with 1 equiv of PhEEPh provided the mono-chalcogen

Formation of (C5Me5)2U(EPh)Me (E ) S, Se, Te)
Organometallics, Vol. 26, No. 17, 2007 4293
intermediates, (C5Me5)2UMe(EPh), 2 (E ) S) and 3 (E ) Se).
These react with an additional equivalent of PhEEPh to make
4 and 5, respectively. The formation of 2, 3, and 6 all occur at
ambient temperature, but formation of the dithiolate 5 requires
heating. This can be rationalized by the fact that a S-S bond is
more difficult to activate than a Se-Se bond and (C5Me5)2-
UMe(SPh) has a less sterically accessible U-Me bond than (C5-
Me5)2UMe2.
but the long bond would lead to less steric crowding. Usually,
the more crowded systems eliminate alkanes more readily, as
in the formation of Schrock carbene and carbyne complexes.34-38
Conclusion
(C5Me5)2UMe2 reacts with 2 equiv of PhEEPh to form (C5-
Me5)2U(EPh)2 (E ) S, Se, Te) in one less step than is required
from [(C5Me5)2UH2]2 starting materials, since (C5Me5)2UMe2
is the precursor to the hydrides. The reaction pathway for the
methyl precursors is not analogous to that of the hydride
complexes since MeEPh byproducts are formed that are
consistent with σ-bond metathesis and (C5Me5)2UMe(EPh)
intermediates can be isolated for S and Se. The reactions provide
facile, halide-free routes to the relatively rare examples of
molecular compounds containing U-Se and U-Te bonds. In
contrast to the S and Se analogues, (C5Me5)UMe(TePh) gener-
ates a C-H activation product, (C5Me5)2U(η2-TeC6H4).
The reaction of 2 equiv of PhTeTePh with (C5Me5)2UMe2
gives the (C5Me5)2U(TePh)2 product, 6, analogous to 4 and 5.
1
However, only H NMR evidence was obtained for (C5Me5)2-
UMe(TePh), the tellurium analogue of 2 and 3. In the absence
of additional PhTeTePh, this complex eliminates methane to
make the C-H activation product (C5Me5)2U(η2-TeC6H4), 7.
Metalation of arene rings has been previously observed in
organoactinide chemistry with (C5Me5)2AnR2 (An ) U, Th; R
) Me, CH2Ph) and pyridine N-oxide, a reaction that generates
metalated (C5Me5)2AnR(η2-ONC5H4) products.30 Pyridine has
also been metalated by (C5Me5)2AnMe2 (An ) U, Th)31 and
U[N(CH2CH2NSiMe2But)2(CH2CH2NSiMeButCH2)].33 Although
this ortho-metalation reactivity is well precedented, it is not clear
why this is observed only in the PhTeTePh reaction and not
with the S and Se analogues. The longer U-Te bond provides
a slightly different metrical arrangement between the methyl
group and the ortho-hydrogen in a (C5Me5)2UMe(EPh) complex,
Acknowledgment. We thank the National Science Founda-
tion for support of this research.
Supporting Information Available: X-ray diffraction details
(CIF) and X-ray data collection, structure solution, and refinement
of compounds 2, 3, 6, and 7 (PDF). This material is available free
of charge via the Internet at http://pubs.acs.org.
(30) Pool, J. A.; Scott, B. L.; Kiplinger, J. L. J. Am. Chem. Soc. 2005,
127, 1338.
OM700382A
(31) Pool, J. A.; Scott, B. L.; Kiplinger, J. L. J. Alloys Compd. 2006,
418, 178.
(32) Beletskaya, I. P.; Voskoboynikov, A. Z.; Shestakova, A. K.;
Yanovsky, A. I.; Fukin, G. K.; Zacharov, L. N.; Struchkov, Y. T.; Schumann,
H. J. Organomet. Chem. 1994, 468, 121.
(33) Boaretto, R.; Roussel, P.; Alcock, N. W.; Kingsley, A. J.; Munslow,
I. J.; Sanders, C. J.; Scott, P. J. Organomet. Chem. 1999, 591, 174.
(34) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 4th ed.; Wiley: New Jersey, 2005; Chapter 11.
(35) Schrock, R. R. J. Chem. Soc., Dalton Trans. 2001, 2541.
(36) Schrock, R. R. Chem. ReV. 2002, 102, 145.
(37) Schrock, R. R. Acc. Chem. Res. 1979, 12, 98.
(38) Schrock, R. R. Science 1983, 219, 13.