C-H and C-S bond cleavage in uranium(III) thiolato complexes

Article abstract of DOI:10.1021/om0102551

Reduction of the uranium(IV) thiolates Cp*₂U(SR)₂ (Cp* = η-C₅Me₅, R = Ph, Me, ⁱPr or ^tBu) with sodium amalgam afforded the corresponding U(III) complexes Na[Cp*₂U(SR)₂] (R = Ph, 2a; Me, 2b; ⁱPr, 2c) or the U(IV) sulfide Na[Cp*₂U(S^tBu)(S)]. C-S bond cleavage of a thiolate ligand was also observed during the thermal decomposition of 2c into the sulfide Na[Cp*₂U(SⁱPr)(S)], whereas 2b was transformed in refluxing THF into the thiametallacyclopropane complex Na[Cp*₂U(SMe)(SCH₂)], resulting from C-H bond activation of a SMe group. The X-ray crystal structures of [Na(18-crown-6)(THF)₂][Cp*₂U(Sⁱ Pr)₂], [Na(18-crown-6)][Cp*₂U(S^tBu)(S)], and [Na(18-crown-6)(THF)₂][Cp*₂U(SMe) (SCH₂)] been determined.

Full text of DOI:10.1021/om0102551

3698
Organometallics 2001, 20, 3698-3703
C-H a n d C-S Bon d Clea va ge in Ur a n iu m (III) Th iola to
Com p lexes
The´re`se Arliguie,* Christophe Lescop, Lionel Ventelon, Pascal C. Leverd,
Pierre Thue´ry, Martine Nierlich, and Michel Ephritikhine*
Service de Chimie Mole´culaire, DRECAM, DSM, CNRS URA 331, CEA Saclay,
91191 Gif sur Yvette, France
Received March 28, 2001
i
Reduction of the uranium(IV) thiolates Cp*2U(SR)2 (Cp* ) η-C5Me5, R ) Ph, Me, Pr or
tBu) with sodium amalgam afforded the corresponding U(III) complexes Na[Cp*2U(SR)2]
i
(R ) Ph, 2a ; Me, 2b; Pr, 2c) or the U(IV) sulfide Na[Cp*2U(StBu)(S)]. C-S bond cleavage
of a thiolate ligand was also observed during the thermal decomposition of 2c into the sulfide
Na[Cp*2U(SiPr)(S)], whereas 2b was transformed in refluxing THF into the thiametalla-
cyclopropane complex Na[Cp*2U(SMe)(SCH2)], resulting from C-H bond activation of a SMe
group. The X-ray crystal structures of [Na(18-crown-6)(THF)2][Cp*2U(SiPr)2], [Na(18-crown-
6)][Cp*2U(StBu)(S)], and [Na(18-crown-6)(THF)2][Cp*2U(SMe)(SCH2)] have been determined.
In tr od u ction
Me5).11 First reactivity studies were focused on the
uranium(IV) thiolates U(SiPr)4,7 Cp3U(SiPr),10 and
Cp*2U(StBu)2;11 they showed that the SR ligand could
undergo substitution reactions and that unsaturated
molecules such as CO2 and CS2 could be inserted into
the U-S bond.
Thiolate compounds of the d-transition metals are of
great interest in various domains of chemistry. Their
importance in biological systems1 and industrial pro-
cesses such as desulfurization2 has been known for a
long time, while their potential in the synthesis of
organosulfur compounds3,4 or metal sulfide materials
has been recognized more recently.5 As a result, many
efforts have been devoted to the synthesis of thiolate
complexes, revealing their large structural diversity and
rich reactivity which are due to the flexibility and
bridging ability of the SR ligand and the presence of
three active sites, i.e., the metal-sulfur, carbon-sulfur,
and carbon-hydrogen bonds.6
Here we report on the reduction reactions of the
bisthiolate compounds Cp*2U(SR)2 (R ) Ph, Me, iPr, and
tBu).12 The stability of the corresponding U(III) anions
[Cp*2U(SR)2]- and their oxidation following C-S or
C-H bond cleavage were found to depend markedly on
the nature of the R group. The uranium(III) complexes
Na[Cp*2U(SPh)2] and [Na(18-crown-6)][Cp*2U(SR)2]
i
(R ) Me, Pr) could be isolated; the isopropyl thiolate
derivative is the first thiolate of U(III) to have been
crystallographically characterized. The uranium(IV)
complexes [Na(18-crown-6)][Cp*2U(StBu)(S)] and [Na-
(18-crown-6)(THF)2][Cp*2U(SMe)(SCH2)], also charac-
terized by their X-ray crystal structure, are the first
f-element compounds containing respectively a metal-
sulfur double bond and a thiametallacyclopropane ring.
By comparison, the chemistry of thiolate compounds
of the f-elements, in particular uranium, was much less
developed, certainly because these complexes have been
long reputed to be unstable. This presumption was
invalidated with the synthesis of the homoleptic com-
7
8
plexes U(SR)4 and Na2U(SR)6 and of the organo-
metallic derivatives (COT)U(SR)2 (COT ) η-C8H8),9
Cp3U(SR) (Cp ) η-C5H5),10 and Cp*2U(SR)2 (Cp* ) η-C5-
Resu lts a n d Discu ssion
(1) (a) Kustin, K.; Macara, I. G. Comments Inorg. Chem. 1982, 2, 1.
(b) Hales, B. J .; Case, E. E.; Morningstar, J . E.; Dzeda, M. F.; Mauterer,
L. A. Biochemistry 1986, 25, 7251. (c) Robson, R. L.; Eady, E. E.;
Richardson, T. H.; Miller, R. W.; Hawkins, M.; Postgate, J . R. Nature
1986, 322, 388. (d) Mandal, S.; Das; G.; Singh, R.; Shukla, R.;
Bharadwaj, P. K. Coord. Chem. Rev. 1997, 160, 191.
(2) (a) Smit, T. S.; J ohnson, K. H. Catal. Lett. 1994, 28, 361. (b)
Druker, S. H.; Curtis, M. D. J . Am. Chem. Soc. 1995, 117, 6366. (c)
Steifel, E. I.; Matasumoto, K. Transition Metal Sulfur Chemistry,
Biological and Industrial Significance; American Chemical Society:
Washington, DC, 1996. (d) Friend, C. M.; Chen, D. A. Polyhedron 1997,
16, 3165. (e) Bianchini, C.; Meli, A. Acc. Chem. Res. 1998, 31, 109.
(3) Firth, A. V.; Stephan, D. W. Organometallics 1997, 16, 2183.
(4) (a) Huang, Y.; Nadasdi, T. T.; Stephan, D. W. J . Am. Chem. Soc.
1994, 116, 5483. (b) Huang, Y.; Etkin, N.; Heyn, R. R.; Nadasdi T. T.;
Stephan, D. W. Organometallics 1996, 15, 2320.
Reduction reactions of the uranium(IV) bisthiolates
Cp*2U(SR)2 (1) with sodium amalgam and thermolysis
(7) (a) Leverd, P. C.; Arliguie, T.; Ephritikhine, M.; Nierlich, M.;
Lance, M.; Vigner, J . New J . Chem. 1993, 17, 769. (b) Leverd, P. C.;
Lance, M.; Vigner, J .; Nierlich, M.; Ephritikhine, M. J . Chem. Soc.,
Dalton Trans. 1995, 237.
(8) (a) Leverd, P. C.; Lance, M.; Nierlich, M.; Vigner, J .; Ephri-
tikhine, M. J . Chem. Soc., Dalton Trans. 1993, 2251. (b) Leverd, P.
C.; Lance, M.; Nierlich, M.; Vigner, J .; Ephritikhine, M. J . Chem. Soc.,
Dalton Trans. 1994, 3563.
(9) Leverd, P. C.; Arliguie, T.; Lance, M.; Nierlich, M.; Vigner, J .;
Ephritikhine, M. J . Chem. Soc., Dalton Trans. 1994, 501.
(10) Leverd, P. C.; Ephritikhine, M.; Lance, M.; Vigner, J .; Nierlich,
M. J . Organomet. Chem. 1996, 507, 229.
(11) Lescop, C.; Arliguie, T.; Lance, M.; Nierlich, M.; Ephritikhine,
M. J . Organomet. Chem. 1999, 580, 137.
(5) Bochmann, M.; Hawkins, I.; Wilson, L. M. J . Chem. Soc., Chem.
Commun. 1988, 344.
(6) (a) Dance, I. G. Polyhedron 1986, 5, 1037. (b) Blower, P. J .;
Dilworth, J . R. Coord. Chem. Rev. 1987, 76, 121. (c) Stephan, D. W.;
Nadasdi, T. T. Coord. Chem. Rev. 1996, 147, 147.
(12) Ventelon, L.; Lescop, C.; Arliguie, T.; Leverd, P. C.; Lance, M.;
Nierlich, M.; Ephritikhine, M. Chem. Commun. 1999, 659.
10.1021/om0102551 CCC: $20.00 © 2001 American Chemical Society
Publication on Web 07/24/2001

Uranium(III) Thiolato Complexes
Organometallics, Vol. 20, No. 17, 2001 3699
Sch em e 1
reactions of the corresponding U(III) compounds Na-
[Cp*2U(SR)2] (2) are summarized in Scheme 1.
Treatment of Cp*2U(SPh)2 (1a ) with 1 equiv of sodium
amalgam in tetrahydrofuran (THF) gave the corre-
sponding anionic uranium(III) compound Na[Cp*2U-
(SPh)2] (2a ). After stirring for 20 h at 20 °C, the solution
was filtered and evaporated to dryness, leaving 2a as a
dark green powder in 93% yield. Complex 2a is ther-
mally stable in solution.
In contrast, Na(Hg) reduction of Cp*2U(SMe)2 (1b) or
Cp*2U(SiPr)2 (1c) was not so clean, and the compounds
i
Na[Cp*2U(SR)2] (R ) Me, 2b, and R ) Pr, 2c) could
not be obtained pure because of slow decomposition in
solution (vide infra). However, in the presence of 18-
crown-6, green microcrystalline powders of [Na(18-
i
crown-6)][Cp*2U(SR)2] (R ) Me, 3b, and R ) Pr, 3c)
1
have been isolated. The H NMR spectra of compounds
2 and 3 exhibit signals corresponding to two Cp* and
two SR ligands; these resonances are broader (30-50
Hz) than those of the U(IV) precursor (10-20 Hz), in
accordance with the +3 oxidation state of uranium.
Reactions of 3 with AgBPh4 gave back the U(IV)
complexes 1 in almost quantitative yield (NMR experi-
ments).
F igu r e 1. View of the crystal structure of the anion
[Cp*2U(SiPr)2]- with displacement ellipsoids drawn at the
20% level.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Na (18-cr ow n -6)(THF )2][Cp *2U(SiP r )2]
After the triscyclopentadienyl derivatives Na[Cp3U-
(SR)],10 2 and 3 are new examples of uranium(III)
thiolates, and [Na(18-crown-6)(THF)2][Cp*2U(SiPr)2],
obtained by crystallization of 3c from THF-pentane,
is the only one to have been crystallographically char-
acterized. The crystals are composed of discrete cation-
anion pairs. The cation displays the expected structural
parameters;13 a view of the anion is shown in Figure 1,
U(1)-C(1) 2.817(3) U(1)-C(2) 2.819(3) U(1)-C(3) 2.812(3)
U(1)-C(4) 2.812(3) U(1)-C(5) 2.823(3) U(1)-C(11) 2.814(3)
U(1)-C(12) 2.786(3) U(1)-C(13) 2.793(3) U(1)-C(14) 2.793(3)
U(1)-C(15) 2.813(3) U(1)-S(1) 2.791(1) U(1)-S(2) 2.777(1)
S(1)-C(21) 1.843(4) S(2)-C(24) 1.840(3)
S(1)-U(1)-S(2)
U(1)-S(2)-C(24)
107.65(3)
117.9(1)
U(1)-S(1)-C(21)
109.3(1)
and selected bond distances and angles are listed in
Table 1. The uranium coordination geometry is the
pseudo-tetrahedral arrangement, which is typical of the
Cp*2MX2 fragment. The U-S bond distances of 2.791-
(1) and 2.777(1) Å are 0.1 Å longer than in Cp*2U(SMe)2
(13) (a) Le Mare´chal, J . F.; Villiers, C.; Charpin, P.; Nierlich, M.;
Lance, M.; Vigner, J .; Ephritikhine, M. J . Organomet. Chem. 1989,
379, 259. (b) Berthet, J . C.; Villiers, C.; Le Mare´chal, J . F.; Delavaux-
Nicot, B.; Lance, M.; Nierlich, M.; Vigner, J .; Ephritikhine, M. J .
Organomet. Chem. 1992, 440, 53.

3700 Organometallics, Vol. 20, No. 17, 2001
Arliguie et al.
[2.640(5) Å],11 in agreement with the difference of ionic
radii between the U(III) and U(IV) centers.14
Not surprisingly, the bis thiolates 2a -c were found
to be much more stable than Na[Cp*2U(StBu)2], in
accordance with the rate at which the C-S bond rupture
occurs in M-SR complexes, depending on the structure
Reaction of Cp*2U(StBu)2 (1d ) with sodium amalgam
was quite different from that of 1a -c since the corre-
sponding U(III) anion could not be detected by NMR,
which revealed instead the ready formation of a product
containing two Cp* ligands for only one StBu group; the
narrow resonances (10-20 Hz) suggested that this
complex was in the +4 oxidation state. NMR and GLC
analyses also revealed the formation of isobutene and
isobutane, which certainly resulted from dismutation
of a tert-butyl radical. These facts suggested that the
likely intermediate Na[Cp*2U(StBu)2] was oxidized into
Na[Cp*2U(StBu)(S)] (4d ) by facile homolytic C-S bond
cleavage of a StBu ligand. Complex 4d was alternatively
synthesized by treating the U(III) chloride [Na(THF)1.5]-
[Cp*2UCl2]15 with NaStBu in THF, and here again,
concomitant formation of isobutene and isobutane was
observed. The reaction mixture was stirred for 18 h at
20 °C, and after filtration and evaporation of the red
solution, the ochre powder of 4d was extracted in
pentane and recovered in 95% yield. In the presence of
18-crown-6, crystallization of 4d from THF-pentane
afforded red needles of [Na(18-crown-6)][Cp*2U(StBu)-
(S)] (5). The X-ray crystal structure of this molecular
heterobimetallic compound was presented in our pre-
liminay communication,12 and only the two most salient
features will be recalled here: the unsupported U-S-
Na linkage and the shortest U-S distance ever ob-
served, 2.462(2) Å, which is consistent with a formal
UdS double bond. Compound 5 can therefore be viewed
as the adduct of the terminal sulfide [Cp*2U(StBu)(S)]-
to [Na(18-crown-6)]+. Among the rare heterobimetallics
containing an unsupported M-S-M′ linkage,16 the
tantalum compound Cp*2Ta(H)(µ-S)W(CO)5 is the only
one to exhibit such a dative coordination of a sulfur lone
pair of the TadS bond.16a
t
i
of R and following the sequence Bu . Pr > Me . Ph.
As already noted, slow decomposition of 2c took place
in THF at room temperature. After 4 h at 65 °C, 2c was
completely decomposed, giving Na[Cp*2U(SiPr)(S)] (4c)
as the major product (ca. 85%, NMR experiments);
concomitant formation of propane, propene, and 2,3-
dimethylbutane confirmed that 2c underwent C-S bond
cleavage of a SiPr group. Encapsulation of the Na+
cation into the crown-ether confers to the uranium(III)
thiolato complexes a greater stability, as shown by the
decomposition of 3c in THF, which was complete after
15 h at 65 °C, instead of 4 h for 2c. This distinct
behavior of 2c and 3c suggests that conversion of the
i
anion [Cp*2U(SR)2]- into [Cp*2U(SR)(S)]- (R ) Pr or
tBu) proceeded by initial formation of the neutral species
Cp*2U(SR), resulting from dissociation of a thiolate
group, followed by C-S bond activation and readdition
of the SR ligand to the sulfide Cp*2U(S). Moreover, the
facility with which the U(III) anions [Cp*2U(SR)2]-
i
t
(R ) Pr, Bu) decompose is in striking contrast to the
thermal stability of their U(IV) precursors. While it has
been noted that reduction of the Ti(IV) thiolate CpTi-
(OC6H3-2,6-iPr2)(Cl)(StBu) promotes the C-S bond rup-
ture of the StBu group,3 the results reported here allow
for the first time a direct comparison between the C-S
bond cleavage reactions of analogous metal thiolates in
different oxidation states. Contrary to previous indica-
tions which suggested that activation of the SR ligand
requires the formation of a µ-thiolate ligand in a
polymetallic species21 and that sulfur abstraction is
favored by a highly oxidized and electrophilic metal
center,20 the results show that low-valent, coordinatively
unsaturated species could facilitate the C-S bond
cleavage reaction, which is of great importance in
catalytic desulfurization processes.
Carbon-sulfur bond cleavage of thiolate ligands,
especially StBu, constitutes a classical route to metal
sulfides.7,17-20 However, the propensity of the sulfide
group to bridge metal atoms is a current obstacle in the
synthesis of complexes containing MdS multiple bonds,
and formation of clusters is frequently observed. This
behavior is illustrated with the facile thermal decom-
position of M(StBu)4 into the trinuclear derivative
M3S(StBu)10 (M ) Zr,20 U7). The stability of 4, the first
f-element compound containing a metal-sulfur double
bond, is likely favored by the negative charge of the
complex and the sterically demanding Cp* ligands
which impede dimerization via U-S-U bridges.18,19
Thermolysis of 2b in refluxing THF was much less
rapid than that of 2c and required 2 days to go to
completion. Here again, the slowing effect of 18-crown-6
was observed, 3b being totally decomposed after 6 days
at 65 °C. Formation of methane, detected by GLC and
MS, confirmed that C-S bond cleavage did occur; the
absence of dimethyl sulfide indicated that this rupture
did not proceed via SN2 attack of SMe- onto the
coordinated SMe group. However, the NMR spectra
showed that the major product, formed in ca. 50% yield,
was not Na[Cp*2U(SMe)(S)] since, in addition to the two
signals attributed to two Cp* and one SMe ligand,
another resonance corresponding to a CH2 group was
also visible. In the presence of 18-crown-6, dark red
crystals were obtained from THF-pentane, and X-ray
diffraction analysis revealed the structure of the thia-
metallacycle [Na(18-crown-6)(THF)2][Cp*2U(SMe)(SCH2)]
(6) (vide infra). Protonation of 6 with NHEt3BPh4 led
to the quantitative formation of 1b (NMR experiments).
Formation of 6 obviously resulted from C-H bond
activation of a SMe ligand of 3b; mechanistic studies of
(14) Shannon, R. D. Acta Crystallogr. 1976, A 32, 751.
(15) Fagan, P. J .; Manriquez, J . M.; Marks, T. J .; Day, C. S.; Vollmer,
S. H.; Day, V. W. Organometallics 1982, 1, 170.
(16) (a) Brunner, H.; Challet, S.; Kubicki, M. M.; Leblanc, J . C.;
Mo¨ıse, C.; Volpato, F.; Wachter, J . Organometallics 1995, 14, 3623.
(b) Massa, M. A.; Rauchfuss, T. B.; Wilson, S. R. Inorg. Chem. 1991,
30, 4667. (c) Kovacs, J . A.; Bergman, R. G. J . Am. Chem. Soc. 1989,
111, 1131.
(17) Piers, W. E.; Koch, L.; Ridge, D. S.; MacGillivray, L. R.;
Zaworotko, M. Organometallics 1992, 11, 3148.
(18) Firth, A. V.; Witt, E.; Stephan, D. W. Organometallics 1998,
17, 3716.
(19) (a) Kawaguchi, H.; Tatsumi, K. Organometallics 1997, 16, 307.
(b) Tatsumi, K.; Inoue, Y.; Kawaguchi, H.; Kohsaka, M.; Nakamura,
A.; Cramer, R. E.; VanDoorne, W.; Taogoshi, G. J .; Richmann, P. N.
Organometalllics 1993, 12, 352.
(20) Coucouvanis, D.; Hadjikyriacou, A.; Kanatzdis, M. G. J . Chem.
Soc., Chem. Commun. 1985, 1224.
(21) (a) Dailey, M. K.; Rauchfuss, T. B.; Rheingold, A. L.; Yap, G. P.
A. J . Am. Chem. Soc. 1995, 117, 6396. (b) Curtis, M. D.; Druker, S. H.
J . Am. Chem. Soc. 1997, 119, 1027. (c) Zhang, X.; Dullaghan, C. A.;
Watson, E. J .; Carpenter, G. B.; Sweigart, D. A. Organometallics 1998,
17, 2067.

Uranium(III) Thiolato Complexes
Organometallics, Vol. 20, No. 17, 2001 3701
Ta ble 2. Selected Bon d Dista n ces (Å) a n d
An gles (d eg) for
[Na (18-cr ow n -6)(THF )2][Cp *2U(SMe)(SCH2)]
U(1)-C(1) 2.798(9) U(1)-C(2) 2.751(8) U(1)-C(3) 2.795(9)
U(1)-C(4) 2.788(9) U(1)-C(5) 2.790(9) U(1)-C(11) 2.794(9)
U(1)-C(12) 2.813(9) U(1)-C(13) 2.813(9) U(1)-C(14) 2.800(9)
U(1)-C(15) 2.807(9) U(1)-C(22) 2.44(1) U(1)-S(1) 2.753(3)
U(1)-S(2) 2.613(3) C(21)-S(1) 1.85(1) C(22)-S(2) 1.74(1)
C(22)-U(1)-S(2)
C(22)-U(1)-S(1)
U(1)-S(1)-C(21)
40.0(3)
127.8(3)
108.1(3)
S(2)-U(1)-S(1)
U(1)-S(2)-C(22)
88.42(9)
64.7(3)
2. The anion of 6 adopts the familiar bent metallocene
structure. The U(1), C(22), S(1), and S(2) atoms are
practically coplanar (within (0.08 Å) and lie in the
equatorial plane that bisects the dihedral angle formed
by the Cp* ligands. The S(1)-U-S(2) angle is equal to
88.42(9)°, and the S(1)‚‚‚S(2) distance is 3.743(4) Å; the
corresponding values in 3c are 107.65(3)° and 4.495(3)
Å. The thiauranacyclopropane ring is very strained, as
shown by the C(22)-U(1)-S(2) and U(1)-S(2)-C(22)
angles of 40.0(3)° and 64.7(3)°, respectively. The U(1)-
C(22) bond distance of 2.44(1) Å is within the range
typically found for other uranium-carbon σ bonds (2.4-
2.6 Å).31 The U(1)-S(2) bond length of 2.613(3) Å is
shorter than the U(1)-S(1) distance of 2.753(3) Å; these
values are at the limits of the range of those determined
for terminally coordinated thiolate ligands, which vary
F igu r e 2. View of the crystal structure of the anion
[Cp*2U(SMe)(SCH2)]- with displacement ellipsoids drawn
at the 10% level.
this process were impeded by the occurrence of the many
side reactions. Such syntheses of thiametallacyclopro-
pane compounds involving C-H bond activation of a
thiolate ligand are very rare, and these consist in the
thermal decomposition of (alkylthio)methyl complexes
of titanium and zirconium. Thus were obtained the
3
dimeric compounds [CpTi(OC6H3-2,6-iPr2)(SCHMe)]2
from 2.58(1) Å in U3(S)(StBu)10 to 2.759(3) Å in
7a
4
and [CpTi(SCHCH2CH2S)]2 and the mononuclear de-
[NEt2H2]2[U(SPh)6].8a The C(22)-S(2) bond length of
1.737(12) Å can be compared to those found in the other
mononuclear thiametallacyclopropanes: 1.744(3) Å in
Cp2Ti(PMe3)(SCH2),25 1.739(13) and 1.785(11) Å in the
two independent molecules of Cp2Zr(PMe3)(SCHMe),22
and 1.742(9) Å in [CpRe(NO)(PPh3)(SCH2)][PF6].24 It
has been generally considered that these distances,
which are intermediate between that determined in
H2CdS (1.6108(9) Å)32 and typical C-S single bonds
(1.80-1.82 Å;33 C(1)-S(1) ) 1.847(10) Å in 6), would
reflect some contribution of the M(η2-SdCHR) resonance
form in the actual structure. Such π-coordination of a
thioformaldehyde ligand would confer to the central
metal of 6 the +2 oxidation state. Although the formally
divalent uranium compound (µ-C7H8)[U(N[Ad]Ar)2]2
(Ad ) adamantyl; Ar ) 3,5-C6H3Me2) has been isolated
recently,34 this valency seems most unlikely in the case
of 6, in view of the strong reducing character of low-
valent uranium complexes and their great reactivity
toward carbonyl groups.
rivative Cp2Zr(PMe3)(SCHR) (R ) Me, Ph).22 Kinetic
data on the decomposition of Cp2Zr(Me)(SCH2R) in the
presence of PMe3 were consistent with intramolecular
loss of methane via a concerted four-center cyclometa-
lation process.23 Complex 6 is the first unsubstituted
thiametallacyclopropane obtained by this M(SMe) f
M(SCH2) transformation. Other thiametallacyclopro-
panes, often considered as η2-thioformaldehyde com-
plexes, have been prepared by a variety of methods
including reactions of methylidene compounds with
alkene sulfides,24-26 hydrogenation and fragmentation
of CS2,27 hydrogenation of thiocarbonyl ligands,28 treat-
ment of iodomethyl iodo metal complexes with NaSH,29
and reactions of diazomethane with sulfido metal com-
pounds.30
Crystals of 6 are composed of discrete cation-anion
pairs. The cation exhibits the expected geometry;13
a
view of the anion is represented in Figure 2, and
selected bond distances and angles are listed in Table
(22) Buchwald, S. L.; Nielsen, R. B.; Dewan, J . C. J . Am. Chem.
Soc. 1987, 109, 1590.
(23) Buchwald, S. L.; Nielsen, R. B. J . Am. Chem. Soc. 1988, 110,
3171.
(24) (a) Buhro, W. E.; Patton, A. T.; Strouse, C. E.; Gladysz, J . A.;
McCormick, F. B.; Etter, M. C. J . Am. Chem. Soc. 1983, 105, 1056. (b)
Buhro, W. E.; Etter, M. C.; Georgiou, S.; Gladysz, J . A.; McCormick,
F. B. Organometallics 1987, 6, 1150.
(25) Park, J . W.; Henling, L. M.; Schaefer, W. P.; Grubbs, R. H.
Organometallics 1990, 9, 1650.
Exp er im en ta l Section
All preparations and reactions were carried out under argon
(<5 ppm oxygen or water) using standard Schlenk-vessel and
vacuum-line techniques or in
a glovebox. Solvents were
thoroughly dried and deoxygenated by standard methods and
distilled immediately before use; THF-d8 was dried over Na-K
alloy.
(26) Adams, R. D.; Babin, J . E.; Tasi, M. Organometallics 1987, 6,
1717.
(27) Adams, R. D.; Golembeski, N. M.; Selegue, J . P. J . Am. Chem.
Soc. 1981, 103, 546.
(28) (a) Collins, T. J .; Roper, W. R. J . Chem. Soc., Chem. Commun.
1977, 901. (b) Collins, T. J .; Roper, W. R. J . Organomet. Chem. 1978,
159, 73.
(31) Hall, S. W.; Huffman, J . C.; Miller, M. M.; Avens, L. R.; Burns,
C. J .; Arney, D. S. J .; England, A. F.; Sattelberger, A. P. Organome-
tallics 1993, 12, 752.
(32) J ohnson, D. R.; Powell, F. X.; Kirchhoff, W. H. J . Mol. Spectrosc.
1971, 39, 136.
(29) Werner, H.; Paul, W. Angew. Chem., Int. Ed. Engl. 1983, 22,
316.
(30) (a) Herberhold, M.; Ehrenreich, W.; Bu¨hlmeyer, W. Angew.
Chem., Int. Ed. Engl. 1983, 22, 315. (b) Herberhold, M.; J ellen, W.;
Murray, H. H. J . Organomet. Chem. 1984, 270, 65.
(33) Sutton, L. E., Ed. Tables of Interatomic Distances and Config-
uration in Molecules and Ions; Chemical Society: London, Supplement
1956-1959, 1965.
(34) Diaconescu, P. L.; Arnold, P. L.; Baker, T. A.; Mindiola, D. J .;
Cummins, C. C. J . Am. Chem. Soc. 2000, 122, 6108.

3702 Organometallics, Vol. 20, No. 17, 2001
Arliguie et al.
Elemental analyses were performed by Analytische Labo-
ratorien at Lindlar (Germany). The 1H NMR spectra were
recorded on a Bruker DPX 200 instrument and were refer-
enced internally using the residual protio solvent resonances
relative to tetramethylsilane (δ 0). The GLC analyses were
performed on a Chrompack CP 9002 apparatus equipped with
a capillary CP Wax 57 CB column. The mass spectra were
obtained using a CEA instrument (electron impact). Sodium
amalgam (2.0% Na) was prepared by adding small pieces of
sodium to mercury under argon at 20 °C; NaStBu was obtained
as a white powder after the reaction of sodium and a slight
excess of tBuSH (1.1 equiv) in THF; the salts NHEt3BPh4 and
AgBPh4 precipitated by mixing NHEt3Cl or AgNO3 and
and a number of unidentified compounds. Methane was
detected by GLC.
Sod iu m Am a lga m Red u ction of 1c a n d Th er m olysis
of 2c. An NMR tube was charged with 1c (7.3 mg, 11 10-3
mmol) and 2% Na(Hg) (12.7 mg, 11 10-3 mmol) in THF-d8 (0.4
mL). After stirring for 24 h at 20 °C, the spectrum showed
that 1c was completely transformed into a mixture containing
1
2c and 4c in the relative proportions of 94:6. H NMR of 2c
(THF-d8): δ -13.8 (s, 12 H, Me), -12.1 (s, 2 H, CH), -3.5 (s,
30 H, Cp*). After heating for 4 h at 65 °C, the spectrum showed
that 2c was totally decomposed, giving 4c as the major product
1
(ca. 85%). H NMR (THF-d8): δ -46.7 (s, 1 H, CH), -19.1 (s,
6 H, Me), 3.12 (s, 30 H, Cp*). Pentamethylcyclopentadiene,
propane, 2,3-dimethylbutane, and a trace of propene were
detected by NMR and GLC-MS.
11
NaBPh4 in water. The compounds Cp*2U(SR)2 and [Na-
(THF)1.5][Cp*2UCl2]15 were synthesized by published methods.
Sod iu m Am a lga m Red u ction of 1d . An NMR tube was
charged with 1d (11.2 mg, 16.3 10-3 mmol) and 2% Na(Hg)
(18.8 mg, 16.3 10-3 mmol) in THF-d8 (0.4 mL). After stirring
for 4 h at 20 °C, the spectrum showed that 1d was completely
transformed into 4d in almost quantitative yield. 1H NMR
Na [Cp *2U(SP h )2] (2a ). A flask was charged with 1a (262
mg, 0.36 mmol) and 2% Na(Hg) (414.5 mg, 0.36 mmol), and
THF (50 mL) was condensed in. The reaction mixture was
stirred at 20 °C for 20 h. After filtration, the solvent was
evaporated off, leaving the product as a dark green powder
(252 mg, 93%). Anal. Calcd for C32H40NaS2U: C, 51.26; H, 5.38;
t
(THF-d8): δ -19.5 (s, 9 H, Bu), 4.3 (s, 30 H, Cp*). Isobutane
and isobutene were detected by NMR and GLC.
1
S, 8.55. Found: C, 51.02; H, 5.46; S, 8.36. H NMR (THF-d8):
[Na(18-cr own -6)][Cp*2U(StBu )(S)] (5). A flask was charged
with [Na(THF)1.5][Cp*2UCl2] (560 mg, 0.79 mmol) and Na-
StBu (313 mg, 2.8 mmol), and THF (50 mL) was condensed
in. After stirring for 18 h at 20 °C, the red solution was filtered
and evaporated to dryness. The residue was extracted in
pentane (50 mL), and the ochre powder of 4d was obtained
after evaporation (482 mg, 95%). Crystallization of this powder
in the presence of 18-crown-6 (198 mg, 0.75 mmol) from THF-
pentane afforded red needles of 5, which were filtered off and
δ -18.8 (s, 4 H, o-Ph), -3.5 (s, 30 H, Cp*), 2.4 (s, 4 H, m-Ph),
3.1 (t, J ) 6 Hz, 2 H, p-Ph).
[Na (18-cr ow n -6)][Cp *2U(SMe)2] (3b). A flask was charged
with 1b (212 mg, 0.35 mmol) and 2% Na(Hg) (405 mg, 0.35
mmol), and THF (50 mL) was condensed in. After 15 h at 20
°C, the solution was filtered and evaporated to dryness. The
1H NMR spectrum of the green powder in THF-d8 showed that
2b was contaminated with ca. 10% of Na[Cp*2U(SMe)(SCH2)].
Crystallization of the green powder (170 mg) in the presence
of 18-crown-6 (71 mg, 0.27 mmol) from THF-pentane afforded
a green microcrystalline powder in an orange solution. After
filtration, the powder was washed with pentane (50 mL) and
dried under vacuum (521 mg, 77%). Anal. Calcd for C36H63
NaO6S2U: C, 47.16; H, 6.92; S, 6.99. Found: C, 46.91; H, 6.78;
-
1
t
S, 6.74. H NMR (THF-d8): δ -17.2 (s, 9 H, Bu), 2.3 (s, 30 H,
Cp*), 4.5 (s, 24 H, 18-crown-6). The same reaction was
monitored by NMR, showing concomitant formation of isobu-
tane and isobutene.
dried under vacuum (168 mg, 54%). Anal. Calcd for C34H60
-
NaO6S2U: C, 45.88; H, 6.79; S, 7.20. Found: C, 41.69; H, 6.39;
S, 6.92 (similar low percentages have been obtained with
distinct samples of 3b, possibly reflecting the difficult combus-
[Na (18-cr ow n -6)(THF )2][Cp *2U(SMe)(SCH2)] (6). A flask
was charged with 1b (268 mg, 0.44 mmol) and 2% Na(Hg) (511
mg, 0.44 mmol), and THF (25 mL) was condensed in. After
stirring for 12 h at 20 °C, the green solution of 2b was filtered
and heated at 65 °C for 40 h. The brown solution was filtered
and evaporated to dryness; 18-crown-6 (58.7 mg, 0.22 mmol)
was added and THF (25 mL) was condensed into the flask.
After filtration and evaporation to dryness, the brown powder
was washed with pentane (30 mL) and extracted with THF
(25 mL). Dark red crystals of 6 were obtained by crystallization
from THF-pentane; these were filtered off and dried under
vacuum (206 mg, 45%). Anal. Calcd for C42H75NaO8S2U: C,
48.82; H, 7.32; S, 6.21. Found: C, 48.91; H, 7.34; S, 6.38. 1H
NMR (THF-d8): δ -2.4 (s, 30 H, Cp*), 3.1 (s, 24 H, 18-crown-
6); 15.2 (s, 3 H, Me); 67.2 (s, 2 H, CH2).
P r oton a tion of 6 w ith NHEt3BP h 4. An NMR tube was
charged with 6 (8.7 mg, 8.4 10-3 mol) and NHEt3BPh4 (3.9
mg, 9.2 10-3 mol) in THF-d8 (0.4 mL). After 5 min at 20 °C,
the spectrum showed the quantitative formation of 1b.
X-r a y Da ta Collection , Str u ctu r e Deter m in a tion , a n d
R efin em en t for [Na (18-cr ow n -6)(TH F )2][Cp *2U(SiP r )2].
Green crystals were obtained by crystallization of 3c from
THF-pentane. A selected crystal was introduced into a
Lindemann glass capillary. Data were collected on a Nonius
Kappa-CCD area detector diffractometer.35 The lattice param-
eters were determined from 10 frames (Φ-scans, 1° steps) and
later refined on all data. A 180° Φ-range was scanned with 2°
steps with a crystal-to-detector distance fixed at 28 mm. Data
were processed and corrected for Lorentz polarization effects
with DENZO-SMN.36 The structure was solved by the heavy-
1
tion of the product). H NMR (THF-d8): δ -21.5 (s, 6 H, Me),
3.4 (s, 24 H, 18-crown-6), 10.85 (s, 30 H, Cp*).
[Na (18-cr ow n -6)][Cp *2U(SiP r )2] (3c). A flask was charged
with 1c (211 mg, 0.32 mmol), 18-crown-6 (86.5 mg, 0.33 mmol),
and 2% Na(Hg) (369 mg, 0.32 mmol), and THF (100 mL) was
condensed in. The reaction mixture was stirred at 20 °C for
24 h, and after filtration, the solution was evaporated to
dryness. The dark green product was washed with toluene
(20 mL) and dried under vacuum (243 mg, 80%). Anal. Calcd
for C38H68NaO6S2U: C, 48.24; H, 7.24; S, 6.78. Found: C, 47.98;
H, 7.09; S, 6.94. 1H NMR (THF-d8): δ -10.3 (s, 12 H, Me),
-6.0 (s, 2 H, CH), -4.2 (s, 30 H, Cp*), 3.8 (s, 24 H, 18-crown-
6).
Rea ction s of 3b a n d 3c w ith AgBP h 4. An NMR tube was
charged with 3b (6.0 mg, 6.7 10-3 mmol) and AgBPh4 (2.9 mg,
6.7 10-3 mmol) in THF-d8 (0.4 mL). After 15 min at 20 °C, the
spectrum showed the quantitative formation of 1b. A similar
reaction with 3c gave 1c.
Sod iu m Am a lga m Red u ction of 1b a n d Th er m olysis
of 2b. A flask was charged with 1a (258 mg, 0.43 mmol) and
2% Na(Hg) (492 mg, 0.43 mmol), and THF (50 mL) was
condensed in. After stirring for 15 h at 20 °C, the solution was
1
filtered and evaporated to dryness. The H NMR spectrum of
the green powder showed that 1b was completely transformed
into a mixture containing 2b and Na[Cp*2U(SMe)(SCH2)] in
the relative proportions of 92:8, and minor impurities (ca 5%).
1H NMR of 2b (THF-d8): δ -11.7 (s, 6 H, Me), -5.2 (s, 30 H,
Cp*). The tube was heated for 2 days at 65 °C, and the
spectrum showed that 2b was totally decomposed, giving Na-
[Cp*2U(SMe)(SCH2)] as the major product (ca. 50%). 1H NMR
(THF-d8): δ -0.4 (s, 30 H, Cp*), 22.3 (s, 2 H, CH2), 32.8 (s, 3
H, Me). The NMR spectrum also showed the formation of Cp*H
(35) Kappa-CCD software, Nonius B. V., Delft, The Netherlands,
1998.
(36) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307.

Uranium(III) Thiolato Complexes
Organometallics, Vol. 20, No. 17, 2001 3703
Ta ble 3. Cr ysta l Da ta a n d Su m m a r y of Da ta
Collection a n d Refin em en t for
X-r a y Da ta Collection , Str u ctu r e Deter m in a tion , a n d
R efin em en t for [Na (18-cr ow n -6)(TH F )2][Cp *2U(SMe)-
(SCH2)] (6). A selected crystal was introduced into a Linde-
mann glass capillary with a protecting Paratone oil (Exxon
Chemical Ltd.) coating. Data were collected on a Nonius
Kappa-CCD area detector diffractometer.35 The lattice param-
eters were determined from 10 frames (Φ-scans, 2° steps) and
later refined on all data. A 180° Φ-range was scanned with 2°
steps with a crystal-to-detector distance fixed at 28 mm. Data
were processed and corrected for Lorentz polarization effects
with DENZO-SMN.36 The structure was solved by direct
methods with SHELXS-9737 and subsequent Fourier-difference
synthesis and refined by full matrix least-squares on F2 with
SHELXL-97.37 Absorption effects were corrected empirically
with the program DELABS from PLATON39 (Tmin ) 0.369,
Tmax ) 0.578). All non-hydrogen atoms were refined with
anisotropic displacement parameters. Hydrogen atoms were
introduced at calculated positions as riding atoms with an
isotropic displacement parameter equal to 1.2(CH, CH2) or 1.5-
(CH3) times that of the parent carbon atom. The molecular
plot was done with SHELXTL.38 All calculations were per-
[Na (18-cr ow n -6)(THF )2][Cp *2U(SiP r )2] a n d
[Na (18-cr ow n -6)(THF )2][Cp *2U(SMe)(SCH2)]
3c‚2THF
6
formula
fw
cryst syst
space group
a (Å)
C
46H84NaO8S2U
C42H75NaO8S2U
1033.16
monoclinic
P21/c
10.7635(11)
21.759(2)
19.8422(12)
94.511(6)
4632.7(7)
4
1090.27
monoclinic
P21/n
17.052(3)
13.883(3)
22.560(5)
102.14(3)
5221.2(2)
4
b (Å)
c (Å)
â (deg)
V (Å3)
Z
D(calcd) (g/cm3)
1.387
3.242
1.481
3.650
µ (mm-1
)
cryst size (mm)
radiation type
temp (K)
θ range, deg
no. of reflns collected 20 168
no of reflns merged
no of reflns obsd
observn criterion
no of params refined
Ra
0.15 × 0.15 × 0.10 0.25 × 0.20 × 0.15
Mo KR
123(2)
Mo KR
100(2)
3.5-25.7
30 124
8443
4.1-20.8
5423
formed on
a Silicon Graphics station. Crystal data and
4522
4554
summary of data collection and refinement are given in
Table 3.
I > 2σ(I)
527
I > 2σ(I)
501
0.044
0.102
1.198
0.058
0.117
1.008
b
Ackn owledgm en t. The authors thank Ge´rard Guille
for his help in recording the MS spectra.
Rw
goodness of fit
a
b
R ) ∑(||Fo| - |Fc||)/∑|Fo|. Rw ) [∑w(||Fo| - |Fc||)2/∑w(|Fo|)2]1/2
.
Su p p or tin g In for m a tion Ava ila ble: Tables giving data
collection and refinement details, atomic coordinates, thermal
parameters, and bond lengths and bond angles of the crystal-
lographically characterized complexes. This material is avail-
able free of charge via the Internet at http://pubs.acs.org.
atom method and subsequent Fourier-difference synthesis and
refined by full matrix least-squares on F2 with SHELXL-97.37
No absorption correction was done. All non-hydrogen atoms
were refined with anisotropic displacement parameters. Hy-
drogen atoms were introduced at calculated positions as riding
atoms with an isotropic displacement parameter equal to
1.2(CH, CH2) or 1.5(CH3) times that of the parent carbon atom.
The molecular plot was done with SHELXTL.38 All calculations
were performed on a Silicon Graphics station. Crystal data
and summary of data collection and refinement are given in
Table 3.
OM0102551
(37) Sheldrick, G. M. SHELXS-97 and SHELXL-97; University of
Go¨ttingen: Germany, 1997.
(38) Sheldrick, G. M. SHELXTL, Version 5.1; Bruker AXS Inc.:
Madison, WI, 1999.
(39) Spek, A. L. PLATON; University of Utrecht: The Netherlands,
2000.