Synthesis, characterization, and reduction chemistry of mixed-cyclopentadienyl/arylsulfide titanium dichlorides

Article abstract of DOI:10.1021/om020847z

A series of titanium derivatives [CpTi(SAr)Cl₂] containing both cyclopentadienyl and various substituted arylsulfide ligands (SAr = SC₆H₄Me-4 (1), SC₆H₂Me₃-2,4,6 (2), SC₆H₂-Pr₃ⁱ-2,4,6 (3), SC₆H₂Ph₃-2,4,6 (4)) has been synthesized from the reaction of [CpTiCl₃] with 1 equiv of the lithium salt of the corresponding arylsulfides in benzene. X-ray diffraction studies show that each metal center possesses a pseudo-tetrahedral geometry. The compounds undergo one-electron reduction to produce sulfur-bridged dimers of the type [CpTiCl(μ-SAr)]₂ (SAr = SC₆H₂Me₃-2,4,6 (5), SC₆H₂Pr₃ⁱ-2,4,6 (6)). The solid-state structures of these dimers show that the cyclopentadienyl rings are arranged in a transoid fashion about the [Ti(μ-SAr)₂Ti] core. The Ti-Ti distances, 3.242(1) and 3.225(1) A respectively, are similar to those found in previously reported Cp/aryloxide dimers with terminal aryloxides and bridging chlorides.

Full text of DOI:10.1021/om020847z

Organometallics 2003, 22, 535-540
535
Syn th esis, Ch a r a cter iza tion , a n d Red u ction Ch em istr y of
Mixed -Cyclop en ta d ien yl/Ar ylsu lfid e Tita n iu m
Dich lor id es
Andrew E. Fenwick, Phillip E. Fanwick, and Ian P. Rothwell*
Department of Chemistry, Purdue University, 560 Oval Drive,
West Lafayette, Indiana 47907-2084
Received October 11, 2002
A series of titanium derivatives [CpTi(SAr)Cl2] containing both cyclopentadienyl and
various substituted arylsulfide ligands (SAr ) SC6H4Me-4 (1), SC6H2Me3-2,4,6 (2), SC6H2-
Pri -2,4,6 (3), SC6H2Ph3-2,4,6 (4)) has been synthesized from the reaction of [CpTiCl3] with
3
1 equiv of the lithium salt of the corresponding arylsulfides in benzene. X-ray diffraction
studies show that each metal center possesses a pseudo-tetrahedral geometry. The compounds
undergo one-electron reduction to produce sulfur-bridged dimers of the type [CpTiCl(µ-SAr)]2
(SAr ) SC6H2Me3-2,4,6 (5), SC6H2Pri -2,4,6 (6)). The solid-state structures of these dimers
3
show that the cyclopentadienyl rings are arranged in a transoid fashion about the [Ti(µ-
SAr)2Ti] core. The Ti-Ti distances, 3.242(1) and 3.225(1) Å, respectively, are similar to those
found in previously reported Cp/aryloxide dimers with terminal aryloxides and bridging
chlorides.
In tr od u ction
fashion.5 These compounds have several advantages
over their Cp counterparts, including tuning of the steric
and electronic properties by changing the substituents
on the aryl moiety. This has provided both novel and
complementary chemistry to the well-studied metal-
locenes. The advent of these compounds has been
followed by the development of mixed-cyclopentadienyl/
aryloxide [CpTi(OAr)Cl2] systems, which have been
structurally compared to the related metallocene [Cp2-
TiCl2] and bis(aryloxide) [(ArO)2TiCl2] systems.6,7 As an
extension of our studies, we have begun an investigation
into related arylsulfide chemistry.
Group 4 organometallic chemistry has been domi-
nated by cyclopentadienyl (Cp) ligation.1 Titanocene
dichloride was first synthesized and reported by Wilkin-
son et al. in 19532 and has been shown to be a versatile
stoichiometric reagent and catalyst precursor. The ef-
ficacy of [Cp2TiCl2] has led to the development of a
number of related titanocenes containing a range of
alkyl-, aryl-, and heteroatom-substituted Cp rings at-
tached to the metal center. Other developments have
included the synthesis of ansa-titanocenes that have the
two Cp rings connected by a hydrocarbon, heteroatom,
or mixed-hydrocarbon/heteroatom bridge group, as well
as the synthesis of chiral titanocenes for use in asym-
metric synthesis and catalysis.3 Alteration of the Cp
ligands has resulted in variations in the physical and
chemical properties of titanocenes. The innovation of
modified titanocenes has also motivated research into
the development of mono-Cp derivatives that contain a
different ligand [CpTi(X)Cl2], including the “constrained
geometry” systems where the Cp and non-Cp ligands
are linked by a bridging group.4
Many substituted arenethiols are known and can
function as ligands that meet a variety of steric and
electronic requirements. Simple benzenethiol, 4-meth-
ylbenzenethiol, and 2,6-dichlorobenzenethiol are com-
mercially available, while 2,6-diphenylbenzenethiol can
be prepared via a Newman-Kwart rearrangement of
2,6-diphenylphenol.8 Trisubstituted 2,4,6-trimethylben-
zenethiol and 2,4,6-triisopropylbenzenethiol are syn-
thesized by the reduction of the corresponding arene-
sulfonyl chloride with lithium aluminum hydride,9 while
2,4,6-triphenylbenzenethiol can be prepared by the
bromination of 1,3,5-triphenylbenzene, followed by lithi-
ation, addition of elemental sulfur, and workup.10 More
Research in the Rothwell group has focused on the
utility of bis(aryloxide) compounds of the type
[(ArO)2TiCl2], in which the aryloxide ligand can be
isolobal with that of cyclopentadienyl, bonding in a σ2π4
(5) Alkoxo and Aryloxo Derivatives of Metals; Bradley, D. C.,
Mehrotra, R. C., Rothwell, I. P., Singh, A., Eds.; Academic Press: San
Diego, CA, 2001; Chapter 6.
(6) Thorn, M. G.; Vilardo, J . S.; Lee, J . T.; Hanna, B.; Fanwick, P.
E.; Rothwell, I. P. Organometallics 2000, 19, 5636.
(7) Nomura, K.; Naga, N.; Miki, M.; Yanagi, K.; Imai, A. Organo-
metallics 1998, 17, 2152.
(8) Bishop, P. T.; Dilworth, J . R.; Nicholson, T.; Zubieta, J . A. J .
Chem. Soc., Dalton Trans. 1991, 385-392.
(9) Blower, P. J .; Dilworth, J . R.; Hutchinson, J .; Nicholson, T.;
Zubieta, J . A. J . Chem. Soc., Dalton Trans. 1985, 2639-2645.
(10) Ruhlandt-Senge, K.; Power, P. P. Bull. Soc. Chim. Fr. 1992,
129, 594-598.
* To whom correspondence should be addressed. E-mail: rothwell@
purdue.edu.
(1) Comprehensive Organometallic Chemistry II; Abel, E. W., Stone,
F. G. A., Wilkinson, G., Eds.; Pergamon: New York, 1995; Vol. 4.
(2) (a) Wilkinson, G.; Pauson, P. L.; Birmingham, J . L.; Cotton, F.
A. J . Am. Chem. Soc. 1953, 75, 15. (b) Wilkinson, G.; Birmingham, J .
L. J . Am. Chem. Soc. 1954, 76, 4281.
(3) Metallocenes: Synthesis, Reactivity, Applications; Togni, A.,
Halterman, R. L., Eds.; Wiley-VCH: Weinheim, Germany, 1998.
(4) Okuda, J .; Eberle, T. In Metallocenes: Synthesis, Reactivity,
Applications; Togni, A., Halterman, R. L., Eds.; Wiley-VCH: Weinheim,
Germany, 1998; pp 415-453.
10.1021/om020847z CCC: $25.00 © 2003 American Chemical Society
Publication on Web 12/21/2002

536 Organometallics, Vol. 22, No. 3, 2003
Fenwick et al.
Sch em e 1
complicated literature procedures also exist for the
synthesis of other arenethiols, including 2,6-diisopro-
pylbenzenethiol,11 2,6-dimesitylbenzenethiol,12 and 2,4,6-
tri-tert-butylbenzenethiol.13
There are numerous studies involving titanium com-
pounds that contain from one to six arylsulfide ligands,
and several crystal structures have been reported.14
However, compounds of the type [CpTi(SAr)Cl2] have
received limited attention. Their utility as cancer in-
hibitors was reported in 1984,15 and in 1996 a process
for manufacturing ethylene R-olefin copolymers in the
presence of cyclopentadienyltitanium catalyst compo-
nents was patented.16 These studies focused on very few
arenethiols, and there are no data reported in the
Cambridge Structural Database for any of these species.
One example of a structurally characterized Ti(III)
dimer with two bridging arylsulfides exists,17 but dimer-
ic species of the type [CpTiCl(µ-SAr)]2 are unknown.
Reported here are the synthesis and characterization
of several compounds of the type [CpTi(SAr)Cl2] and
dimeric species of the type [CpTiCl(µ-SAr)]2 formed via
one-electron reductions of the [CpTi(SAr)Cl2] complexes.
The solid-state structures of these compounds are
compared to those of the analogous aryloxide systems.
Although the dichlorides may have biological applica-
tions,18 we are interested in their potential synthetic
applications, particularly as titanacycle precursors.
method, the phenol was added to [CpTiCl3] in the
presence of pyridine, resulting in the desired product
and pyridinium hydrochloride. This method proved
unsuccessful for the synthesis of the arylsulfide systems,
resulting instead in a large amount of the previously
reported [pyH][CpTiCl4],6 as confirmed by X-ray crystal-
lography. In the second method, lithiation of the ben-
zenethiol using n-butyllithium and subsequent addition
of the lithio salt to [CpTiCl3] resulted in a good yield of
the desired product (Scheme 1). The NMR spectra of
1-4 were as expected, with one Cp resonance and a
Resu lts a n d Discu ssion
Syn th esis a n d Ch a r a cter iza tion of Mon ocyclo-
p en ta d ien yltita n iu m Ar ylsu lfid e Com p lexes. Syn-
thesis of the mixed-cyclopentadienyl/arylsulfide com-
pounds was attempted using two methods employed
successfully for the aryloxide analogues. In the first
1
single set of arylsulfide signals in each case. In the H
NMR spectrum of 1-3, the Cp protons were observed
at δ 6.13, 6.12, and 6.15 ppm, respectively, which are
shifted downfield from the δ 5.3-6.0 ppm range typical
for [CpTi(OAr)Cl2] compounds. The Cp resonance for 4
appears further upfield at δ 5.78 ppm as a result of the
diamagnetic shielding by the ortho phenyl rings.
Compounds 1-4 have been analyzed by X-ray crys-
tallography (Table 1), and ORTEP drawings for 2 and
4 are represented in Figures 1 and 2, respectively. The
titanium dichlorides exhibit a pseudo-tetrahedral ge-
ometry about the metal center. Selected structural
parameters, along with those for related [(X)Ti(Y)Cl2]
derivatives (X, Y ) Cp, OAr),6,19 are collected in Table
2. The Ti-Cl bond distance decreases as Cp is replaced
by OAr and, to a lesser extent, upon replacement by
SAr, reflecting the relative electrophilicity at the metal
center. The Cp-Ti-S bond angles are substantially
contracted compared to those of the analogous X-Ti-Y
angles in the bis(Cp), bis(aryloxide), or mixed-Cp/
aryloxide compounds. In addition, the Ti-S-C bond
angle is significantly smaller than the Ti-O-C bond
angles in the analogous systems. The largest Ti-S-C
bond angle observed in these systems is 107°, while the
smallest reported Ti-O-C angle is 150°.
(11) Schrock, R. R.; Wesolek, M.; Liu, A. H.; Wallace, K. C.; Dewan,
J . C. Inorg. Chem. 1988, 27, 2050-2054.
(12) Ellison, J . J .; Ruhlandt-Senge, K.; Power, P. P. Angew. Chem.,
Int. Ed. Engl. 1994, 33, 1178-1180.
(13) Look, K.; Norris, R. K. Aust. J . Chem. 1999, 52, 1077-1083.
(14) (a) Osakada, K.; Hosoda, T.; Yamamoto, T. Bull. Chem. Soc.
J pn. 2000, 73, 923-930. (b) Alcock, N. W.; Clase, H. J .; Duncalf, D. J .;
Hart, S. L.; McCamley, A.; McCormack, P. J .; Taylor, P. C. J .
Organomet. Chem. 2000, 605, 45-54. (c) Carmalt, C. J .; Dinnage, C.
W.; Parkin, I. P.; White, A. J . P.; Williams, D. J . J . Chem. Soc., Dalton
Trans. 2000, 3500-3504. (d) Kim, J . T.; Park, J . W.; Koo, S. M.
Polyhedron 2000, 19, 1139-1143. (e) Lindsell, W. E.; Rosair, G. M.;
Spence, M. A. J . Organomet. Chem. 1999, 577, 9-14. (f) Firth, A. V.;
Stephan, D. W. Inorg. Chem. 1998, 37, 4732-4734. (g) Delgado, E.;
Garcia, M. A.; Hernandez, E.; Mansilla, N.; Martinez-Cruz, L. A.;
Tornero, J .; Torres, R. J . Organomet. Chem. 1998, 560, 27-33. (h) Dias,
A. R.; Galvao, A. M.; Galvao, A. C.; Salema, M. S. J . Chem. Soc., Dalton
Trans. 1997, 1055-1061. (i) Firth, A. V.; Stephan, D. W. Organome-
tallics 1997, 16, 2183-2188. (j) Corwin, D. T., J r.; Corning, J . F.; Koch,
S. A.; Millar, M. Inorg. Chim. Acta 1995, 229, 335-342. (k) Delgado,
E.; Hernandez, E.; Hedayat, A.; Tornero, J .; Torres, R. J . Organomet.
Chem. 1994, 466, 119-123. (l) Nadasdi, T. T.; Huang, Y.; Stephan, D.
W. Inorg. Chem. 1993, 32, 347-356. (m) Nadasdi, T. T.; Stephan, D.
W. Inorg. Chem. 1993, 32, 5933-5938. (n) Sigel, G. A.; Power, P. P.
Inorg. Chem. 1987, 26, 2819-2822. (o) Besancon, J .; Camboli, D.;
Trimaille, B.; Dusausoy, Y. C. R. Seances Acad. Sci., Ser. 2 1985, 301,
83-86. (p) Shaver, A.; McCall, J . M.; Bird, P. H.; Ansari, N. Organo-
metallics 1983, 2, 1894-1896. (q) Muller, E. G.; Watkins, S. F.; Dahl,
L. F. J . Organomet. Chem. 1976, 111, 73-89.
(15) Koepf-Maier, P.; Grabowski, S.; Koepf, H. Eur. J . Med. Chem.s
Chem. Ther. 1984, 19, 347-352.
(16) Watanabe, T.; Katayama, H.; Imai, A. J P Patent 95-13553
19950131; J pn. Kokai Tokkyo Koho, 1996.
(17) Firth, A. V.; Stephan, D. W. Inorg. Chem. 1998, 37, 4726-4731.
(18) (a) Robson, R. L.; Eady, R. R.; Richardson, T. H.; Miller, R. W.;
Hawkins, M.; Postgate, J . R. Nature 1986, 322, 388. (b) Hales, B. J .;
Case, E. E.; Morningstar, J . E.; Dzeda, M. F.; Mauterer, L. A.
Biochemistry 1986, 25, 7251. (c) Steifel, E. I.; Matasumoto, K. Transi-
tion Metal Sulfur Chemistry: Biological and Industrial Significance;
American Chemical Society: Washington, DC, 1996.
Known Ti-S-C bond angles for terminal arylsulfides
on titanium metal centers range from 87 to 123°, on the
basis of a survey of all reported examples.14 A plot of
Ti-S distances versus the Ti-S-Ar angles indicates
that Ti-S bonds are typically between 2.27 and 2.45 Å
(19) (a) Clearfield, A.; Warner, D. K.; Saldarriaga-Molina, C. H.;
Ropal, R. Can. J . Chem. 1975, 53, 1622. (b) Dilworth, J . R.; Hanich,
J .; Krestel, M.; Beck, J .; Strahle, J . J . Organomet. Chem. 1986, 315,
C9. (c) Waratuke, S. A.; Thorn, M. G.; Fanwick, P. E.; Rothwell, A. P.;
Rothwell, I. P. J . Am. Chem. Soc. 1999, 121, 9111.

Cyclopentadienyl/ Arylsulfide Ti Dichlorides
Organometallics, Vol. 22, No. 3, 2003 537
Ta ble 1. Cr ysta l Da ta a n d Da ta Collection P a r a m eter s
1
2
3
4
5
6
formula
C
12H12Cl2STi
C14H16Cl2STi
C20H28Cl2STi
C29H22Cl2STi
C28H32Cl2S2Ti2‚
0.5C6H6
638.46
C40H56Cl2S2Ti2
fw
307.10
P21/n (No. 14)
7.6209(2)
12.8769(3)
13.9754(3)
90
101.139(2)
90
1345.6(1)
4
335.15
419.32
521.37
767.73
Pna21 (No. 33)
18.7973(6)
13.8957(4)
15.6199(4)
90
space group
a, Å
b, Å
P1h (No. 2)
6.7592(2)
6.9746(2)
16.9957(6)
90.454(2)
97.183(2)
108.217(1)
754.15(8)
2
P1h (No. 2)
6.1625(2)
11.1142(4)
15.2861(5)
87.012(2)
89.194(2)
89.751(2)
1045.4(1)
2
P21/n (No. 14)
11.0173(2)
18.7419(5)
12.9144(3)
90
113.717(1)
90
2441.4(2)
4
P1h (No. 2)
8.6789(4)
10.7494(6)
16.961(1)
90.039(3)
96.658(3)
92.549(2)
1570.1(3)
2
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
90
90
4079.9(2)
4
1.250
F
calcd, g cm-3
temp, K
1.516
150
1.476
170
1.332
150
1.418
150
1.350
193
150
radiation (wavelength, Å)
R
Rw
Mo KR (0.710 73)
0.031
0.078
0.039
0.095
0.071
0.167
0.037
0.096
0.075
0.135
0.049
0.110
F igu r e 1. ORTEP (50% thermal ellipsoids) view of [CpTi-
(SC6H2Me3-2,4,6)Cl2] (2).
F igu r e 3. Variation of Ti-S distance with Ti-S-Ar angle
for terminal arylsulfides on titanium metal centers.
amalgam (1 equiv of Na/Ti) leads to the formation of 5,
which can be isolated in good yield as a burgundy solid
upon precipitation from benzene with pentane. Reaction
of 3 with 1 equiv of trimethylaluminum (TMA) affords
a dark burgundy solution from which 6 was isolated.
The 1H NMR spectrum of 6 indicates the presence of
diastereotopic methyl groups on the o-isopropyl substit-
uents. Compounds 5 and 6 have been analyzed by X-ray
diffraction (Table 1). Selected bond distances and angles
are listed in Tables 3 and 4, respectively, and an ORTEP
drawing of 6 is shown in Figure 4. The solid-state
structures show dinuclear compounds with a [Ti(µ-
SAr)2Ti] core and terminal chloride and Cp groups. The
Cp ligands are arranged in a transoid fashion about the
core, and the molecule contains a C2 axis that runs
through the two sulfur atoms.
F igu r e 2. ORTEP (50% thermal ellipsoids) view of [CpTi-
(SC6H2Ph3-2,4,6)Cl2] (4).
The analogous aryloxide system is also dimeric, but
it contains bridging chlorides and terminal aryloxides.
The cyclopentadienyl compound characterized by Stucky
et al. exhibits an average Ti-Ti bond length of 3.96 Å,
which is too long for any metal-metal interaction.21 In
the diamagnetic bis(2,6-diphenylphenoxide) species, a
much shorter distance of 2.9827(7) Å is observed,22 and
the bond lengths in the mixed Cp/OAr species range
from 3.19 to 3.336(1) Å. The Ti-Ti distances in 5 and 6
are 3.242(1) and 3.225(1) Å, respectively, which are
similar to those found for Cp/OAr compounds containing
in length, and most Ti-S-Ar angles lie within a small
range (Figure 3). These observations differ dramatically
from those of titanium aryloxides, where a survey of
Ti-O distances versus Ti-O-Ar angles on four-
coordinate titanium displays Ti-O-Ar angles covering
a much wider range (approximately 110-180°).20
Dim er iza tion via On e-Electr on Red u ction . The
one-electron reduction of 2 and 3 was first attempted
using a sodium/mercury amalgam (Scheme 2), the
method typically used for the analogous aryloxides.
Treatment of a benzene solution of 2 with sodium
(21) J ungst, R.; Sekutowski, D.; Davis, J .; Luly, M.; Stucky, G. Inorg.
Chem. 1977, 7, 1645.
(22) Schmid, G.; Thewalt, U.; Sedmera, P.; Hanus, V.; Mach, K.
Collect. Czech. Chem. Commun. 1998, 63, 636.
(20) Alkoxo and Aryloxo Derivatives of Metals; Bradley, D. C.,
Mehrotra, R. C., Rothwell, I. P., Singh, A., Eds.; Academic Press: San
Diego, CA, 2001; p 474.

538 Organometallics, Vol. 22, No. 3, 2003
Ta ble 2. Str u ctu r a l P a r a m eter s for [(X)Ti(Y)Cl2] (X, Y ) Cp , OAr , SAr )
Fenwick et al.
Ti-O/S, Å
[Ti-O/S-C, deg]
X-Ti-Y,
deg
Cl-Ti-Cl,
O/S-Ti-Cl,
deg
Cp-Ti-Cl,
compd
Ti-Cl, Å
Ti-Cp, Å
deg
deg
[Cp2TiCl2]19a
2.367(2)
2.361(1)
2.255(1)
2.2396(9)
2.256(2)
2.232(2)
2.230(2)
2.244(2)
2.2597(8)
2.2690(8)
2.334(2)
2.321(2)
2.2666(8)
2.2609(7)
2.206(1)
2.058 (av)
131
115
116
119
118
118
94
102
102
102
99
106 (av)
[CpTi(OC6HPh4-2,3,5,6)Cl2]6
[CpTi(OC6HNp2-2,6-Me2-3,5)Cl2]6
[CpTi(OC6HNp2-2,6-But2-3,5)Cl2]6
[CpTi(OC6H2Ph-2-But2-4,6)Cl2]6
[CpTi(OC6H2Np-2-But2-4,6)Cl2]6
[CpTi(OC6H3-{C3H5}-2-Me-6)Cl2]6
[Ti(OC6H3Ph2-2,6)2Cl2]19b
2.016(6)
2.010(8)
2.04(1)
1.796(2)
[150]
1.780(4)
[153]
1.774(3)
[164]
1.785(2)
[160]
1.786(1)
[159]
1.780(2)
[155]
1.726(2)
[169]
1.734(7)
[167]
106
115
114
114
114
112
114
114
113
113
113
104
105
103
106
102
104
105
106
103
102
104
111
2.022(4)
2.028(2)
101
102
113
111
109
109
[Ti(OC6H3Me2-2,6)2Cl2]19c
2.192(4)
2.211(4)
109, 109
108, 110
1.736(8)
[169]
2.2924(5)
[100]
2.2912(7)
[107]
2.287(1)
[97]
1a
2a
3a
4a
2.2371(5)
2.2528(5)
2.2522(8)
2.2557(7)
2.240(1)
2.251(1)
2.2430(8)
2.2513(8)
2.014
107
105
107
105
103
102
103
103
107
106
107
108
106
107
106
109
116
117
118
117
116
117
116
117
2.017
2.026(5)
2.019(4)
2.2851(8)
[97]
a
This work.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 5
Sch em e 2
Ti(1)-Ti(2)
Ti(1)-Cl(1)
Ti(2)-Cl(2)
Ti(1)-S(1)
Ti(1)-S(2)
Ti(2)-S(1)
3.242(1)
2.278(2)
2.280(2)
2.326(2)
2.322(2)
2.303(2)
Ti(2)-S(2)
Ti(1)-Cp
2.306(2)
2.020
2.026
1.783(5)
1.787(5)
Ti(2)-Cp
S(1)-C(111)
S(2)-C(211)
Ti(1)-S(1)-C(111) 137.1(2)
Ti(1)-S(2)-C(211) 137.6(2)
Ti(2)-S(1)-C(111) 134.0(2)
Ti(2)-S(2)-C(211) 133.5(2)
S(1)-Ti(1)-S(2)
S(1)-Ti(2)-S(2)
Ti(1)-S(1)-Ti(2)
Ti(1)-S(2)-Ti(2)
90.38(5)
91.36(5)
88.90(5)
88.93(5)
117.0
Cl(1)-Ti(1)-S(1)
Cl(1)-Ti(1)-S(2)
Cl(2)-Ti(2)-S(1)
Cl(2)-Ti(2)-S(2)
105.81(7) Cp-Ti(1)-Cl(1)
104.31(7) Cp-Ti(1)-S(1)
105.47(7) Cp-Ti(1)-S(2)
103.04(7)
117.4
118.0
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 6
Ti(1)-Ti(2)
Ti(1)-Cl(1)
Ti(2)-Cl(2)
Ti(1)-S(3)
Ti(1)-S(4)
3.225(1)
2.282(1)
2.293(2)
2.319(1)
2.320(1)
Ti(2)-S(3)
Ti(2)-S(4)
Ti(1)-Cp
S(3)-C(31)
S(4)-C(41)
2.309(1)
2.314(1)
2.018(6)
1.795(4)
1.799(4)
Ti(1)-S(3)-C(31)
Ti(1)-S(4)-C(41)
Ti(2)-S(3)-C(31)
Ti(2)-S(4)-C(41)
Cl(1)-Ti(1)-S(3)
Cl(1)-Ti(1)-S(4)
Cl(2)-Ti(2)-S(3)
Cl(2)-Ti(2)-S(4)
137.2(2)
133.0(2)
134.5(2)
138.7(2)
105.15(5)
105.84(5)
104.63(5)
104.22(5)
S(3)-Ti(1)-S(4)
S(3)-Ti(2)-S(4)
Ti(1)-S(3)-Ti(2)
Ti(1)-S(4)-Ti(2)
Cp-Ti(1)-Cl(1)
Cp-Ti(1)-S(3)
Cp-Ti(1)-S(4)
91.41(5)
91.79(4)
88.37(4)
88.22(4)
117.7(2)
117.3(2)
115.9(2)
from 5 and 6. They contain bridging alkanedithiolate
or benzylthiolate moieties, and the Ti centers are
formally d0, precluding any metal-metal bonding. The
Ti-Ti distances obtained from the Cambridge Struc-
bridging chlorides. The nature of this d1-d1 interaction
has been discussed by Rothwell et al.6
(23) (a) Firth, A. V.; Witt, E.; Stephan, D. W. Organometallics 1998,
17, 3716. (b) Huang, Y.; Etkin, N.; Heyn, R. R.; Nadasdi, T. T.; Stephan,
D. W. Organometallics 1996, 15, 2320. (c) Huang, Y.; Nadasdi, T. T.;
Stephan, D. W. J . Am. Chem. Soc. 1994, 116, 5483.
A few Ti-Ti dimers with bridging thiolates have been
reported,23 and most exhibit two distinct differences

Cyclopentadienyl/ Arylsulfide Ti Dichlorides
Organometallics, Vol. 22, No. 3, 2003 539
triphenylbenzenethiol10 were prepared according to literature
procedures or slight variations thereof. All other reagents were
purchased from Aldrich Chemical Co., Inc., and used as
received. The 1H NMR spectra were recorded on a Varian
Inova-300 spectrometer and were referenced to residual protio
solvent. The 13C NMR spectra were recorded at 75.4 MHz on
a Varian Inova-300 spectrometer and were internally refer-
enced to the solvent signal. Elemental analyses and X-ray
diffraction studies were performed in-house at Purdue Uni-
versity. Elemental analyses for 4 and 6 were omitted due to
the low percentage of carbon found. This is caused by the
formation of carbide species, which is typical for early-
transition-metal organometallic compounds.
F igu r e 4. ORTEP (50% thermal ellipsoids) view of [Cp-
TiCl(µ-SC6H2Pri -2,4,6)]2 (6).
3
[Cp Ti(SC6H4Me-4)Cl2] (1). To a solution of 4-methylben-
zenethiol (0.57 g, 4.6 mmol) in benzene (50 mL) was slowly
added a solution of n-BuLi (1.84 mL, 2.5 M in hexanes) via
syringe. There was a noticeable increase in temperature, and
the solution became opaque as the lithio salt of the arylsulfide
formed. The resulting suspension was stirred for several hours
and then was added to a solution of [CpTiCl3] (1.00 g, 4.6
mmol) in benzene (100 mL), resulting in a color change from
green to deep red. The mixture was stirred overnight under
nitrogen and then was filtered through a frit using a plug of
Celite. The clear, red filtrate was dried in vacuo, yielding a
bright orange solid (0.78 g, 55%). The crude product was
redissolved in benzene and layered with pentane to obtain
X-ray-quality crystals. Anal. Calcd for C12H12Cl2STi: C, 46.94;
H, 3.94; Cl, 23.09; S, 10.44. Found: C, 46.55; H, 4.07; Cl, 22.74;
S, 10.12. 1H NMR (C6D6, 25 °C): δ 7.67 (d, m-H); 7.01 (d, o-H);
6.13 (s, Cp); 2.00 (s, p-Me). 13C NMR (C6D6, 25 °C): δ 139.8,
138.5, 132.8, 130.5 (aromatics); 119.7 (Cp); 21.0 (p-Me).
[Cp Ti(SC6H2Me3-2,4,6)Cl2] (2). To a solution of 2,4,6-
trimethylbenzenethiol (1.39 g, 9.1 mmol) in benzene (100 mL)
was slowly added a solution of n-BuLi (3.64 mL, 2.5 M in
hexanes) via syringe. The resulting suspension was stirred for
2 h and then was added to a solution of [CpTiCl3] (2.00 g, 9.1
mmol) in benzene (150 mL). The mixture was stirred overnight
under nitrogen and then was filtered through a frit with a plug
of Celite. The clear, red filtrate was concentrated in vacuo and
layered with pentane, yielding bright red-orange crystals (2.28
g, 75%). Anal. Calcd for C14H16Cl2STi: C, 50.18; H, 4.81; Cl,
21.16; S, 9.57. Found: C, 49.98; H, 4.79; Cl, 20.99; S, 9.56. 1H
NMR (C6D6, 25 °C): δ 6.91 (s, m-H); 6.12 (s, Cp); 2.44 (s, o-Me);
2.09 (s, p-Me). 13C NMR (C6D6, 25 °C): δ 140.1, 138.9, 129.7,
129.1 (aromatics); 119.6 (Cp); 22.3, 20.9 (methyls).
Ta ble 5. Ti-Ti Bon d Len gth s in Dim er s
compd
Ti-Ti, Å
21
[Cp2Ti(µ-Cl)]2
[(OC6H3Ph2-2,6)2Ti(µ-Cl)]2
3.96 (av)
2.9827(7)
3.19b
3.336(1)
3.3942(8)
3.242(1)
3.225(1)
24
17
[CpTi(OC6H3Pri2-2,6)(µ-Cl)]2
6
[CpTi(OC6H2Np-2-But2-4,6)(µ-Cl)]2
17
[CpTi(OC6H3Pri2-2,6)(µ-SPh)]2
5a
6a
a
b
This work. Obtained from Cambridge Structural Database.
tural Database range from 3.418 to 4.117 Å in these
compounds. The only reported structure closely related
to 5 and 6 is the compound [CpTi(OC6H3Pri -2,6)(µ-
2
SPh)]2, which is a dimer containing two bridging ben-
zenethiolates and terminal Cp and aryloxide ligands.17
This diamagnetic species has a Ti-Ti distance of 3.3942-
(8) Å, slightly longer than those of 5 and 6. The S-phenyl
ring of this species approaches coplanarity with the
slightly puckered Ti2S2 plane, which differs from 5 and
6, where the S-aryl ring is nearly perpendicular to the
Ti2S2 plane. Table 5 lists Ti-Ti bond lengths for 5 and
6 along with selected related dimeric species.6,17,21,24
Su m m a r y a n d Con clu sion s
Several mixed-cyclopentadienyl/arylsulfide titanium
dichlorides have been prepared and structurally char-
acterized. This represents the first structurally char-
acterized compound of the type [CpTi(SAr)Cl2], and
their parameters have been compared to those of various
analogous aryloxide species.
[Cp Ti(SC6H2P r i3-2,4,6)Cl2] (3). To a solution of 2,4,6-
triisopropylbenzenethiol (2.00 g, 8.5 mmol) in benzene (60 mL)
was slowly added a solution of n-BuLi (3.4 mL, 2.5 M in
hexanes) via syringe. The resulting suspension was stirred for
2 h and then was added to a solution of [CpTiCl3] (1.85 g, 8.5
mmol) in benzene (60 mL). The mixture was stirred overnight
under nitrogen and then was filtered through a frit using a
plug of Celite, and the clear, red filtrate was dried in vacuo.
The crude product was washed several times with pentane,
yielding a bright orange solid (2.86 g, 81%). A small amount
of product was redissolved in benzene and layered with
pentane to obtain X-ray-quality crystals. Anal. Calcd for
C20H28Cl2STi: C, 57.29; H, 6.73; Cl, 16.91; S, 7.65. Found: C,
57.64; H, 6.77; Cl, 16.53; S, 7.94. 1H NMR (C6D6, 25 °C): δ
The one-electron reduction of these compounds pro-
duces a dimer containing bridging arylsulfides and
terminal cyclopentadienyl and chloride ligands. The Ti-
Ti bond lengths are 3.242(1) and 3.225(1) Å for [CpTiCl-
(µ-SC6H2Me3-2,4,6)]2 and [CpTiCl(µ-SC6H2Pri -2,4,6)]2,
3
which are similar to those of the mixed-cyclopentadi-
enyl/aryloxide species with bridging chlorides.
Exp er im en ta l Section
3
7.33 (s, m-H); 6.15 (s, Cp); 3.56 (septet, o-CHMe2), J (1H-1H)
Gen er a l Deta ils. All manipulations were carried out under
a dry nitrogen atmosphere using standard Schlenk techniques.
Hydrocarbon solvents were distilled from sodium/benzophe-
none and stored over sodium ribbon under nitrogen prior to
use. The synthesis of [CpTiCl3] was carried out according to a
literature procedure.25 Pyridine was stored over KOH and 4
Å molecular sieves prior to use. The reagents 2,4,6-trimeth-
ylbenzenethiol,9 2,4,6-triisopropylbenzenethiol,9 and 2,4,6-
) 6.8 Hz; 2.83 (septet, p-CHMe2), 3J (1H-1H) ) 6.8 Hz; 1.38
3
3
(d, o-CHMe2), J (1H-1H) ) 6.8 Hz; 1.22 (d, p-CHMe2), J (1H-
1H) ) 6.8 Hz. 13C NMR (C6D6, 25 °C): δ 151.8, 148.43, 138.5,
122.3 (aromatics); 119.7 (Cp); 34.6, 33.1 (CHMe2); 24.1, 23.9
(methyls).
[Cp Ti(SC6H2P h 3-2,4,6)Cl2] (4). To a solution of 2,4,6-
triphenylbenzenethiol (1.70 g, 5.0 mmol) in benzene (50 mL)
was slowly added a solution of n-BuLi (2.0 mL, 2.5 M in
hexanes) via syringe. The resulting suspension was stirred for
2 h and then was added to a solution of [CpTiCl3] (1.00 g, 4.6
mmol) in benzene (100 mL). The mixture was stirred overnight
(24) Hill, J . E.; Fanwick, P. E.; Rothwell, I. P. Polyhedron 1990, 9,
1617.
(25) Cotton, F. A.; Wojtczac, W. A. Gazz. Chim. Ital. 1993, 123, 499.

540 Organometallics, Vol. 22, No. 3, 2003
Fenwick et al.
under nitrogen and then was filtered through a frit using a
plug of Celite, and the filtrate was dried in vacuo, yielding a
red oil. The crude product was redissolved in a minimum of
benzene and layered with hexane, yielding dark red crystals
(0.70 g, 30%). 1H NMR (C6D6, 25 °C): δ 7.75-7.10 (aromatics);
5.78 (s, C5H5).13C NMR (C6D6, 25 °C): δ 130.4-127.4 (aromat-
ics); 119.4 (Cp).
[Cp TiCl(µ-SC6H2Me3-2,4,6)]2 (5). A solution of 2 (0.50 g,
1.5 mmol) in benzene (40 mL) was added to a benzene solution
containing sodium (0.04 g, 1.7 mmol) as a mercury amalgam.
The mixture was stirred overnight. The dark red mixture was
decanted from the amalgam and filtered through a plug of
Celite over fritted glass to remove Na and Hg salts. The
solution was dried under vacuum, and the dark solid was
redissolved in benzene and layered with pentane to yield large
quantities of burgundy crystals (0.30 g, 63%). Anal. Calcd for
C28H32Cl2S2Ti2‚0.5C6H6: C, 58.32; H, 5.53; Cl, 11.11; S, 10.04.
Found: C, 57.92; H, 5.54; Cl, 11.01; S, 9.74. 1H NMR (C6D6,
25 °C): δ 6.75 (s, m-H); 6.20 (s, Cp); 2.29 (s, o-Me); 2.07 (s,
p-Me). 13C NMR (C6D6, 25 °C): δ 142.2, 130.0, 128.4, 127.1
(aromatics); 113.4 (Cp); 22.4, 20.8, (methyls).
under a cold stream of dry nitrogen. Preliminary examination
and final data collection were performed with Mo KR radiation
(λ ) 0.710 73 Å) on a Nonius KappaCCD instrument. Lorentz
and polarization corrections were applied to the data.26 An
empirical absorption correction using SCALEPACK was ap-
plied.27 Intensities of equivalent reflections were averaged. The
structure was solved using the structure solution program
PATTY in DIRDIF92.28 The remaining atoms were located in
succeeding difference Fourier syntheses. Hydrogen atoms were
included in the refinement but restrained to ride on the atom
to which they are bonded. The structure was refined in full-
matrix least squares, where the function minimized was
2
2
2
∑w(|Fo| - |Fc| )2 and the weight w is defined as w ) 1/[σ2(Fo
)
2
+ (0.0585P)2 + 1.4064P] (P ) (Fo2 + 2Fc )/3). Scattering factors
were taken from ref 29. Refinement was performed on a
AlphaServer 2100 using SHELX-97.30 Crystallographic draw-
ings were done using the programs ORTEP.31
Ack n ow led gm en t. We thank the National Science
Foundation (Grant CHE-0078405) for financial support
of this research.
[Cp TiCl(µ-SC6H2P r i3-2,4,6)]2 (6). To a solution of 3 (1.75
g, 4.2 mmol) in toluene (50 mL) was added trimethylaluminum
(4.2 mL, 2.0 M in toluene) via syringe. The mixture was stirred
for 3 h. The dark red mixture was filtered through fritted glass
to remove Al salts. The solution was dried under vacuum and
rinsed several times with pentane, yielding a burgundy solid
(0.92 g, 57%). A small amount of the product was dissolved in
pentane and recrystallized by slow evaporation, affording
X-ray-quality crystals. 1H NMR (C6D6, 25 °C): δ 7.21 (s, m-H);
6.27 (s, Cp); 3.62 (septet, o-CHMe2), 3J (1H-1H) ) 6.7 Hz; 2.76
(septet, p-CHMe2), 3J (1H-1H) ) 6.8 Hz; 1.32 (d, p-CHMe2),
3J (1H-1H) ) 6.6 Hz; 1.21 (d, o-CHMeMe′), 3J (1H-1H) ) 6.7
Hz; 1.20 (d, o-CHMeMe′), 3J (1H-1H) ) 6.8 Hz. 13C NMR (C6D6,
25 °C): δ 153.2, 150.9, 128.5, 123.4 (aromatics); 113.4 (Cp);
34.5, 31.3 (CHMe2); 25.7, 24.2, 24.0, 24.0 (methyls).
Su p p or tin g In for m a tion Ava ila ble: Tables giving X-ray
crystallographic data for 1-6 and ORTEP drawings for 1, 3,
and 5. This material is available free of charge via the Internet
at http://pubs.acs.org.
OM020847Z
(26) McArdle, P. C. J . Appl. Crystallogr. 1996, 239, 306.
(27) Otwinowski, Z.; Minor, W. Methods Enzymol. 1996, 276.
(28) Beurskens, P. T.; Admirall, G.; Beurskens, G.; Bosman, W. P.;
Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
DIRDIF92 Program System; Technical Report; Crystallography Labo-
ratory, University of Nijmegen, Nijmegen, The Netherlands, 1992.
(29) International Tables for Crystallography; Kluwer Academic:
Dordrecht, The Netherlands, 1992; Vol. C, Tables 4.2.6.8 and 6.1.1.4.
(30) Sheldrick, G. M. SHELXS97: A Program for Crystal Structure
Refinement; University of Gottingen, Gottingen, Germany, 1997.
(31) J ohnson, C. K. ORTEPII; Report ORNL-5138; Oak Ridge
National Laboratory, Oak Ridge, TN, 1976.
X-r a y Da ta Collection a n d Red u ction . Crystal data and
data collection parameters are contained in Table 1. A suitable
crystal was mounted on a glass fiber in a random orientation