Synthesis and characterisation of derivatives of monocyclopentadienylbis(arene-1,2-dithiolato)titanium(IV); crystal structures of M[Ti(η5-C5Me5)(1,2-S2C 6H4)2] [M = Tl or N(PPh3)2]

Article abstract of DOI:10.1039/a800890f

Thallium(I) derivatives of monocyclopentadienylbis(arene-1,2-dithiolato)titanium, Tl[Ti(η⁵-C₅H_nMe_5-n)-(S ₂C₆H₃R)₂ (1-6; n = 0, 4 or 5; R = H or Me), have been synthesised and isolated in yields of 31-65% from reactions of the corresponding trichloromonocyclopentadienyltitanium reagents, Ti(η⁵-C₅H_nMe_5-n)Cl₃ and thallium salts of the benzene- 1,2-dithiol or toluene-3,4-dithiol in tetrahydrofuran. Reaction between Tl[Ti(η⁵-C₅Me₅)(1,2-S₂C ₆H₄)₂] and bis(triphenylphosphine)iminium chloride, [N(PPh₃)₂]Cl, has also afforded the derivative [N(PPh₃)₂][Ti(η⁵-C₅Me ₅)(1,2-S₂C₆H₄)₂] 7. Products have been characterised by elemental analysis, NMR, IR and mass spectroscopy, and by X-ray diffraction. The structure of 7, in the crystalline state as a tris(dichloromethane) solvate, comprises an ionic lattice containing discrete [Ti(η⁵-C₅Me₅)(1,2-S₂C ₆H₄)₂]^- anions of four-legged piano stool geometry with two chelating benzene-1,2-dithiolate ligands folded along the S ... S axis in exo and endo conformations, respectively, relative to the cyclopentadienyl ring. The crystal structure of Tl[Ti(η⁵-C₅Me₅)(S₂C ₆H₄)₂] 1 contains two forms of the anion [Ti(η⁵-C₅Me₅)(S₂C ₆H₄)]^- in endolendo and endolexo conformations, respectively, which are unsymmetrically co-ordinated to the Tl^I cations. A Tl^I ion is connected by two Tl-S bonds to endo dithiolate ligands of each anion and there is also one Tl-S interaction between pairs of endolendo and endolexo forms. Additional weaker Tl ... S interactions to the Tl^I ions generate a linked chain of dimeric units. In solution, NMR spectra suggest a more symmetrical structure for all derivatives but shifts in resonances support the retention of co-ordinate links between the cyclopentadienylbis(arene-1,2-dithiolato)titanium anion and Tl^I.

Full text of DOI:10.1039/a800890f

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Synthesis and characterisation of derivatives of monocyclopenta-
dienylbis(arene-1,2-dithiolato)titanium(IV); crystal structures of
M[Ti(ç5-C5Me5)(1,2-S2C6H4)2] [M ؍ Tl or N(PPh3)2]
Malcolm A. Spence, Georgina M. Rosair and W. Edward Lindsell*,†
Department of Chemistry, Heriot-Watt University, Riccarton, Edinburgh UK, EH14 4AS
Thallium() derivatives of monocyclopentadienylbis(arene-1,2-dithiolato)titanium, Tl[Ti(η5-C5HnMe5 Ϫ n)-
(S2C6H3R)2 (1–6; n = 0, 4 or 5; R = H or Me), have been synthesised and isolated in yields of 31–65% from
reactions of the corresponding trichloromonocyclopentadienyltitanium reagents, Ti(η5-C5HnMe5 Ϫ n)Cl3
and thallium salts of the benzene-1,2-dithiol or toluene-3,4-dithiol in tetrahydrofuran. Reaction between
Tl[Ti(η5-C5Me5)(1,2-S2C6H4)2] and bis(triphenylphosphine)iminium chloride, [N(PPh3)2]Cl, has also afforded
the derivative [N(PPh3)2][Ti(η5-C5Me5)(1,2-S2C6H4)2] 7. Products have been characterised by elemental analysis,
NMR, IR and mass spectroscopy, and by X-ray diffraction. The structure of 7, in the crystalline state as a
tris(dichloromethane) solvate, comprises an ionic lattice containing discrete [Ti(η5-C5Me5)(1,2-S2C6H4)2]Ϫ
anions of four-legged piano stool geometry with two chelating benzene-1,2-dithiolate ligands folded along the
S ؒ ؒ ؒ S axis in exo and endo conformations, respectively, relative to the cyclopentadienyl ring. The crystal structure
of Tl[Ti(η5-C5Me5)(S2C6H4)2] 1 contains two forms of the anion [Ti(η5-C5Me5)(S2C6H4)2]Ϫ in endo/endo and
endo/exo conformations, respectively, which are unsymmetrically co-ordinated to the TlI cations. A TlI ion is
connected by two Tl᎐S bonds to endo dithiolate ligands of each anion and there is also one Tl᎐S interaction
between pairs of endo/endo and endo/exo forms. Additional weaker Tl ؒ ؒ ؒ S interactions to the TlI ions generate
a linked chain of dimeric units. In solution, NMR spectra suggest a more symmetrical structure for all derivatives
but shifts in resonances support the retention of co-ordinate links between the cyclopentadienylbis(arene-1,2-
dithiolato)titanium anion and TlI.
Previous work in this laboratory on Group 6 metals has estab-
lished various aspects of the chemistry of monocyclopenta-
dienyl-molybdenum- and -tungsten-thiolates and shown that
Results and Discussion
Syntheses and general characterisations
anionic complexes, particularly those containing four fluoro-
arylthiolate ligands, will co-ordinate to thallium and larger
Group 1 metal ions.1 Complexes such as [MoCp(SC6F5)4]Ϫ
(Cp = η5-C5H5) have four-legged piano stool geometry and
a metal counter ion can be held within the cavity defined by the
four sulfur atoms, the transition metal and four ortho-fluorine
substituents of the aromatic rings.2 Monocyclopentadienyl-
thiolato derivatives of earlier Group 4 and 5 transition
metals have received little attention until relatively recently.3
The preparation of simple thiolate derivatives of mono-
cyclopentadienyltitanium() was reported in 1968,4 but sub-
sequent studies by Köpf and co-workers were not published
until the late 1980s.5 Stephan and co-workers have since
published a series of papers on propane-1,3 and ethane-
1,2-dithiolate derivatives of cyclopentadienyltitanium,3,6–8
including several compounds structurally characterised by
X-ray diffraction.
Unsaturated ene- or arene-1,2-dithiolates (dithiolenes) are
generally more versatile sulfur ligands9 and complexes of
monocyclopentadienyltitanium [TiCp(S᎐S)2]Ϫ, with S᎐S =
maleonitriledithiolate (mnt),10a,b 3,4,5,6-tetrachlorobenzene-
1,2-dithiolate,10c toluene-3,4-dithiolate11 (tdt) and benzene-1,2-
dithiolate,12 (bdt), are known. These anionic complexes have
only been characterised with non-co-ordinating counter
cations, [NEt4]ϩ or [PPh4]ϩ, and the crystal structure of ionic
[PPh4][TiCp(1,2-S2C6H4)2] has been determined.12 Herein we
report arene-1,2-dithiolates of monocyclopentadienyltitanium
containing cyclopentadienyl rings with differing degrees of
alkyl substitution (η5-C5HnMe5 Ϫ n, n = 0, 4 or 5) and the
influence of Tlϩ as an interacting counter ion.
Reactions of the thallium salts of benzene-1,2-dithiol and
toluene-3,4-dithiol with trichloro(η5-pentamethylcyclopenta-
dienyl)titanium, TiCp*Cl3 (Cp* = η5-C5Me5) in 2:1 molar
ratios in tetrahydrofuran (thf) afforded the bimetallic dithiolate
derivatives TlTiCp*(bdt)2 1 and TlTiCp*(tdt)2 2, [H2bdt = 1,2-
(HS)2C6H4; H2tdt = 3,4-(HS)2C6H3CH3], as crystalline, dark
red-purple solids in yields of 65 and 32%, respectively. When
equimolar amounts of Tl2tdt and TiCp*Cl3 were reacted under
similar conditions the only isolable product was also TlTiCp*-
(tdt)2, albeit in rather low yield (17%). Similar reactions
between thallium salts of benzene-1,2-dithiolate or toluene-3,4-
dithiolate with TiCpЈCl3 (CpЈ = η5-C5H4Me) or TiCpCl3 gave
the corresponding products TlTiCpЈ(bdt)2 3, TlTiCpЈ(tdt)2 4,
TlTiCp(bdt)2 5 and TlTiCp(tdt)2 6 in isolable yields of 31–41%.
The identities of the new products have been established by
1
elemental analysis, H NMR spectra and, in some cases, FAB
mass spectrometry. All complexes are thermally stable as solids
or in solution, but are susceptible to hydrolysis. Complexes 1
and 2 dissolve in toluene, thf and chlorinated organic solvents
but with decreasing methyl substitution of the cyclopentadienyl
ring the compounds become progressively less soluble and
compound 5 is sparingly soluble in toluene, chloroform and
dichloromethane, in contrast to the reported solubility12 of the
related ionic species, [PPh4][TiCp(bdt)2].
In the 1H NMR spectra of 1 and 2 the hydrogens of the Cp*
ligands give rise to one sharp singlet resonance. At ambient
temperature, the aromatic hydrogen resonances of the benzene
rings of 1 occur as well defined AAЈ and BBЈ multiplets of two
equivalent AAЈBBЈ systems, of correct relative intensity and
with JAB 7.7, JABЈ 1.5, JAAЈ ≈ 0.1 and JBB ≈ 7.1 Hz, obtained
by simulation. For compound 2, the methyl hydrogens of the
toluene ligands give rise to only one singlet resonance and
† E-Mail: W.E.Lindsell@hw.ac.uk
J. Chem. Soc., Dalton Trans., 1998, Pages 1581–1586
1581

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R2
R2
R1
R1
R1
R1
Table
1 Selected interatomic distances (Å) and angles (Њ) for
R1
R1
R1
compound 7
R3
R1
R3
Ti
S
S
R3
Ti᎐S(1)
Ti᎐S(2)
Ti᎐S(3)
Ti᎐S(4)
N(1)᎐P(1)
N(1)᎐P(2)
2.432(2)
2.419(2)
2.414(2)
2.446(2)
1.588(5)
1.575(5)
Ti᎐C(10)
Ti᎐C(11)
Ti᎐C(12)
Ti᎐C(13)
Ti᎐C(14)
2.390(6)
2.404(6)
2.399(6)
2.390(6)
2.381(6)
Ti
S
S
S
S
S
S
Tl+
Tl+
R3
endo/endo
exo/endo
S(2)᎐Ti᎐S(1)
S(3)᎐Ti᎐S(2)
S(3)᎐Ti᎐S(4)
S(1)᎐Ti᎐S(4)
S(3)᎐Ti᎐S(1)
S(2)᎐Ti᎐S(4)
C(35)᎐C(30)᎐S(3)
P(2)᎐N(1)᎐P(1)
N(1)᎐P(1)᎐C(40)
N(1)᎐P(1)᎐C(50)
N(1)᎐P(2)᎐C(90)
82.33(6)
79.33(6)
80.41(6)
81.84(6)
130.86(7)
135.62(7)
120.3(4)
140.4(3)
113.3(3)
111.8(3)
109.8(3)
C(20)᎐S(1)᎐Ti
C(25)᎐S(2)᎐Ti
C(30)᎐S(3)᎐Ti
C(35)᎐S(4)᎐Ti
C(25)᎐C(20)᎐S(1)
C(20)᎐C(25)᎐S(2)
C(30)᎐C(35)᎐S(4)
N(1)᎐P(1)᎐C(60)
N(1)᎐P(2)᎐C(80)
N(1)᎐P(2)᎐C(70)
98.3(2)
98.2(2)
105.5(2)
104.5(2)
120.7(4)
120.3(5)
118.6(4)
108.8(3)
110.1(3)
115.3(2)
R2
R1
R1
R1
R1
Ti
S
S
S
S
Tl+
exo/exo
R3
R3
1
3
5
R1 = R2 = Me, R3 = H
R1 = H, R2 = Me, R3 = H
R1 = R2 = H, R3 = H
2
4
6
R1 = R2 = Me, R3 = 1-Me
R1 = H, R2 = Me, R3 = 1-Me
R1 = R2 = H, R3 = 1-Me
Scheme 1
the aromatic resonances occur as multiplets assignable to three
inequivalent hydrogens of two equivalent rings. Therefore, there
is no evidence from the NMR spectrum for the existence of
isomers which could result from syn and anti placements of the
two methyl substituents and this may indicate the preferential
formation of one isomeric form. Proton NMR spectra of the
other thallium compounds 3–6 show similar resonances for
hydrogen nuclei of two equivalent benzene or toluene dithiolate
ligands and resonances typical of CpЈ or Cp rings, as appropri-
ate, with correct relative intensities (see Experimental section).
Possible conformations of the dithiolate ligands are illustrated
in Scheme 1.
The FAB mass spectrum of 1 shows a strong parent ion,
[TlTiCp*(bdt)2]ϩ, with a pattern of m/z values corresponding to
isotopic distributions, and other bands include fragmentation
ions formed by loss of Cp* and Tl, as well as peaks for 203/205Tlϩ.
A weak signal around m/z = 879 can be assigned to the dithal-
lium ion [Tl2TiCp*(bdt)2]ϩ. Other dithiolate derivatives did not
give clear molecular ions but showed fragmentation ions in
FAB mass spectra. The IR spectra of the new compounds
include bands typical of cyclopentadienyl and arenedithiolate
ligands.
Fig. 1 Perspective view of ion pairs of [N(PPh3)2][TiCp*(bdt)2]ؒ
3CH2Cl2, 7ؒ3CH2Cl2 (50% probability displacement ellipsoids)
structural analysis by X-ray diffraction, minimising loss of
dichloromethane and disintegration of the crystal. Fig. 1
shows a perspective view of the structure of an anion/cation
pair, with relevant atom labelling and Table 1 lists selected geo-
metrical parameters. The compound is clearly ionic with
[TiCp*(bdt)2]Ϫ and [N(PPh3)2]ϩ existing as discrete units. The
solvent molecules do not appear to interact strongly with
the ions, with the shortest contacts between CH2Cl2 and
[TiCp*(bdt)2]Ϫ being H ؒ ؒ ؒ S(3) at 2.884(8) Å and C ؒ ؒ ؒ S(3) at
3.750(8) Å. The geometry of the [N(PPh3)2]ϩ cation is as
expected.
The titanium atom in the complex anion has a four-legged
piano stool arrangement of ligating atoms. The four sulfur
atoms lie on an approximate plane (root mean square, r.m.s.
deviation 0.045 Å) opposite the plane of Cp* ring at an inter-
planar angle of 2.1(3)Њ. The Ti᎐S distances are in the range
2.414(2)–2.446(2) Å; on average these are slightly longer than
Ti᎐S bonds in [PPh4][TiCp(bdt)2],12 or in terminal thiolates of
neutral monocyclopentadienyltitanium() species,6–8 but the
longer distances are comparable to Ti᎐S bond lengths in [TiCp-
{S2(CH2)n}2]Ϫ (n = 2 or 3).7,8 The Ti᎐Cp* (centroid) distance of
2.066 Å is close to that found in [PPh4][TiCp(bdt)2] (2.060 Å),12
and S᎐Ti᎐Cp* (centroid) angles are in the range 111.1–116.1Њ.
The two benzenedithiolate ligands are folded along the
S ؒ ؒ ؒ S axis relative to the adjacent TiS2 plane but have different
conformations. One benzenedithiolate is endo with respect to the
Cp* ring, with a dihedral angle Ti᎐S(3)᎐S(4)/S(3)᎐S(4)᎐C6H4
of 27.3(1)Њ, and the other is exo, with an angle Ti᎐S(1)᎐S(2)/
S(1)᎐S(2)᎐C6H4 of 40.3(1)Њ. An endo/exo conformation was
proposed for the neutral compound [TaCp*(SCH᎐CHS) ],13
A metathetical reaction of TlTiCp*(bdt)2 1 with 1 equivalent
of bis(triphenylphosphine)iminium chloride, [N(PPh3)2]Cl, in
dichloromethane produced the derivative [N(PPh3)2][TiCp*-
(bdt)2] 7. This product initially crystallised from dichloro-
methane–light petroleum as a solvate with CH2Cl2, and crystals
suitable for study by X-ray diffraction had the stoichiometry
[N(PPh3)2][TiCp*(bdt)2]ؒ3CH2Cl2. However, dichloromethane
is readily lost from the isolated solid at room temperature, so
that the crystals for structural analysis had to be handled exped-
itiously and kept at low temperature (see below). Thorough dry-
ing under vacuum removed dichloromethane to give unsolvated
1
7, as shown by elemental analysis and the H NMR spectrum,
which included distinguishable aromatic resonances assignable
to two equivalent benzenedithiolate ligands and a [N(PPh3)]ϩ
cation. The complex [PPh4][TiCp*(bdt)2] was similarly pre-
1
pared from 1 and [PPh4]Br, and characterised by its H NMR
spectrum.
᎐
2
Solid-state structure of compound 7
and was also observed in the solid-state structure of the anion
in [PPh4][TiCp(bdt)2],12 but the dihedral angles in the latter
species, 36.3Њ (endo) and 23.3Њ (exo) differ significantly from
Large needle-like crystals of solvated 7, [N(PPh3)2][TiCp*-
(bdt)2]ؒ3CH2Cl2, were cut and rapidly cooled to 160 K for
1582
J. Chem. Soc., Dalton Trans., 1998, Pages 1581–1586

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Table
2
Selected interatomic distances (Å) and angles (Њ) for
compound 1
Ti(1)᎐S(1)
Ti(1)᎐S(2)
Ti(1)᎐S(3)
Ti(1)᎐S(4)
Tl(1)᎐S(1)
Tl(1)᎐S(2)
Tl(1)᎐S(3)
Tl(1)᎐S(4)
Tl(1)᎐S(7)
Tl(1)᎐S(2A)
Ti(1)᎐C(14)
Ti(1)᎐C(10)
Ti(1)᎐C(11)
Ti(1)᎐C(12)
Ti(1)᎐C(13)
2.418(3)
2.436(3)
2.438(3)
2.427(3)
3.436(3)
3.518(4)
3.296(3)
3.157(3)
3.472(3)
3.430(3)
2.356(10)
2.366(10)
2.393(9)
2.419(10)
2.422(9)
Ti(2)᎐S(5)
Ti(2)᎐S(6)
Ti(2)᎐S(7)
Ti(2)᎐S(8)
Tl(2)᎐S(5)
Tl(2)᎐S(7)
Tl(2)᎐S(8)
Tl(2)᎐S(3)
Tl(2)᎐S(8B)
Ti(2)᎐C(22)
Ti(2)᎐C(24)
Ti(2)᎐C(23)
Ti(2)᎐C(21)
Ti(2)᎐C(20)
2.421(3)
2.423(3)
2.410(3)
2.480(3)
3.412(3)
3.167(3)
3.148(3)
3.173(2)
3.338(2)
2.353(9)
2.371(9)
2.377(9)
2.399(10)
2.400(10)
Fig. 3 Structure of TlTiCp*(bdt)2 showing weak Tl ؒ ؒ ؒ S interactions
S(1)᎐Ti(1)᎐S(2)
S(4)᎐Ti(1)᎐S(3)
S(4)᎐Ti(1)᎐S(2)
S(1)᎐Ti(1)᎐S(3)
S(2)᎐Ti(1)᎐S(3)
S(1)᎐Ti(1)᎐S(4)
C(51)᎐C(50)᎐S(1)
C(50)᎐C(51)᎐S(2)
C(60)᎐C(65)᎐S(3)
C(40)᎐C(41)᎐S(8)
80.58(11)
80.94(10)
78.19(11)
78.96(11)
132.44(12)
127.19(11)
119.9(8)
119.4(9)
118.7(8)
119.9(8)
S(5)᎐Ti(2)᎐S(6)
S(7)᎐Ti(2)᎐S(6)
S(7)᎐Ti(2)᎐S(8)
S(5)᎐Ti(2)᎐S(8)
S(7)᎐Ti(2)᎐S(5)
S(6)᎐Ti(2)᎐S(8)
C(30)᎐C(35)᎐S(5)
C(35)᎐C(30)᎐S(6)
C(41)᎐C(40)᎐S(7)
C(65)᎐C(60)᎐S(4)
81.99(11)
79.32(11)
79.96(10)
80.88(11)
125.34(12)
137.99(11)
119.4(8)
121.9(8)
119.4(8)
121.0(8)
and a fragment of the chain structure (ortho-phenylene groups of
benzenedithiolate ligands omitted for clarity)
distance lying in the range 2.418(3)–2.438(3) Å; Ti(2)᎐S(8)
[2.480(3) Å] is slightly longer, although distances of this magni-
tude are found in titanium() compounds with thiolates co-
ordinated to a second titanium centre or to CuI or RhI.6–8
The Ti᎐Cp* (centroid) distances are 2.074 and 2.055 Å, and
S᎐Ti᎐Cp* (centroid) angles are in the ranges 112.7–116.4 and
110.8–118.0Њ for A and B, respectively.
The conformations of the aromatic dithiolate ligands differ
from that in compound 7, In A, the ligands adopt an endo/endo
conformation, with dihedral angles between TiS2 and S2C6H4
planes of 43.4(2) and 7.5(3)Њ. In B the conformation is endo/
exo, as in 7, but the respective dihedral angles are 35.2(2) and
23.0(2)Њ. In both forms, one thallium ion is more closely associ-
ated with one organotitanium anion and lies trans to the Cp*
ligand, with an angle 174.8Њ for Tl(1)᎐Ti(1)᎐Cp* (centroid) in A
and 169.8Њ for Tl(2)᎐Ti(2)᎐Cp* (centroid) in B, and interacts
unsymmetrically with the sulfur atoms of the dithiolate ligands.
In A, there are two shorter Tl᎐S distances of 3.157(3) and
3.296(3) Å to the more folded dithiolate ligand, S(3)C6H4S(4).
The bending of the dithiolate ligands permits greater inter-
action of sulfur electron pairs with thallium and these TlI᎐S
bond lengths are comparable with those in [TlMoCp(SC6F5)4]1
and in crown thioether complexes [Tl([9]aneS3)]ϩ and
[Tl([18]aneS3)]ϩ,14a and are within the range of the four TlI᎐S
interactions on the dimeric anion [Tl2(bdt)2]2Ϫ 15
. There are also
two longer Tl ؒ ؒ ؒ S distances of 3.436(3) and 3.518(4) Å, to the
less folded dithiolate ligand, and two Tl ؒ ؒ ؒ S distances to
neighbouring anions of 3.430(3) and 3.472(3) Å (see Fig. 3);
these lengths are comparable to others in systems where weak
Tl ؒ ؒ ؒ S interactions have been claimed but are larger than the
sum of the formal ionic radii of TlI and S (3.34 Å).14
Fig. 2 Perspective view of the two structurally different units of
TlTiCp*(bdt)2 1 (30% probability displacement ellipsoids)
There are two short Tl᎐S bonds in B between the associated
Tl(2) and the endo-dithiolate ligand with lengths of 3.167(3)
and 3.148(3) Å, and the shortest distance involves S(8) which
has the longest Ti᎐S bond. The Tl᎐S distances to the exo-
dithiolate of B are 3.412(3) and 3.910(3) Å [to S(6)], indicative
of weakly and non-interacting atoms, respectively, and are con-
sistent with the unfavourable orientation of electron pairs on
these sulfurs; there is also a distance, Tl(2)᎐S(8B), of 3.338(2) Å
to the neighbouring species related by a centre of inversion.
More significant, however, is the short Tl(2)᎐S(3) contact of
3.173(2) Å linking Tl(2) to the dithiolate ligand of the adjacent
anion of molecule A (see Fig. 3). This bridging interaction
involving Tl(2) creates dimers from pairs of A and B units. If
the longer, weak Tl ؒ ؒ ؒ S interactions are also considered, the
overall crystal structure comprises chains of these dimeric
entities (Fig. 3). The long Tl ؒ ؒ ؒ Ti distances of 3.557(2) Å in A
and 3.581(2) Å in B and the minimum Tl ؒ ؒ ؒ Tl separation of
4.174(2) Å preclude any significant metal–metal interactions.
those of 7. These differences in dihedral angles may be attrib-
uted to the presence of the five methyl substituents on the
cyclopentadienyl ring of 7.
Solid-state structure of compound 1
The structure of a single crystal of 1 was determined by X-ray
diffraction at ambient temperature, and selected geometrical
parameters are listed in Table 2. There are two crystallo-
graphically independent TlTiCp*(bdt)2 units which are linked
via S(3), and these are depicted as A and B in Fig. 2, with
relevant atom labelling. In both forms, the titanium has the
four-legged piano stool arrangement of ligating atoms, with the
least-squares plane of the four sulfur atoms (r.m.s. deviations:
A, 0.047; B, 0.115 Å) being close to parallel with the plane of the
Cp* ring [interplanar angles: A, 1.3(6); B 1.4(6)Њ]. The Ti᎐S
bond lengths are similar to those in 7, with all but one Ti᎐S
J. Chem. Soc., Dalton Trans., 1998, Pages 1581–1586
1583

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NMR studies in solution
evidence for weaker interactions with sulfur atoms of the less
folded endo ligand and with sulfur atoms of two neighbouring
TlTiCp*(bdt)2 units. The TlI closely associated with the endo/
exo complex (B) interacts weakly with one sulfur atom of the
exo ligand and with a sulfur atom of a neighbouring B unit but
is also more strongly associated with a sulfur atom of an
adjacent complex A. The overall crystalline structure can be
considered to comprise dimeric [TlTiCp*(bdt)2]2 units weakly
1
Low-temperature H NMR spectra of 1, down to Ϫ90 ЊC (in
CD2Cl2) or to Ϫ119 ЊC (in CF3Cl–CD2Cl2), merely show a
slight broadening of all resonances, with the loss of structure of
the AAЈBBЈ multiplet of the aromatic hydrogens at temper-
atures < Ϫ70 ЊC. Although this broadening could be related to
a slowing of intramolecular conformational interchanges of
benzenedithiolate ligands, it is also consistent with an increase
in solvent viscosity at the low temperature, and since no new
resonances were observed the spectra provide no clear evidence
for inequivalence of the benzenedithiolate rings of 1 in solu-
tion, contrary to the different conformations of these ligands
found in the crystal. Moreover, no inequivalences of arene-
dithiolate (or of cyclopentadienyl groups) were observed for the
other products and this has also been observed by Köpf and
co-workers for other monocyclopentadienyltitaniumdithiolat-
es.11,12 This may be due to rapid, time-averaged interchange of
endo and exo ligands, although barriers for such inversions in
arenedichalcogenates of dicyclopentadienylmetal systems have
been monitored by variable-temperature NMR and are >40 kJ
1
linked in chains. In solution, H NMR spectra of the thallium
derivatives support the presence of co-ordinative interactions
between organometallic dithiolate anions and TlI.
Experimental
All reactions and operations were conducted under an atmos-
phere of dry, oxygen-free nitrogen gas, using Schlenk tech-
niques. All solvents were thoroughly dried, using sodium
(toluene), sodium–benzophenone (diethyl ether, tetrahydro-
furan, light petroleum) or calcium hydride (dichloromethane),
and freshly distilled before use. Light petroleum had a boiling
17
18
molϪ1 16
Alternatively, in solution the dithiolate anions may
.
range of 60–80 ЊC. Starting materials TiCp*Cl3
,
TiCpЈCl3
and TiCpCl3 were prepared by literature methods. Benzene-
) ]Cl and thallium()
19
adopt a more symmetrical form with equivalent ligands.
1
1,2-dithiol, toluene-3,4-dithiol, [N(PPh3
2
The H NMR data for the thallium complex 1 and related
[N(PPh3)2]ϩ derivative 7 show significant differences between
the chemical shifts of AAЈ and BBЈ components of the benzene-
dithiolate ligands and a smaller variation in the chemical shift
of the Cp* rings. Thus, in CDCl3 under similar conditions, the
AAЈ and BBЈ multiplets occur at δ 7.39 and 6.97 in 1 and at
δ 7.15 and 6.50 in 7, respectively, with the latter shifts being
unchanged on replacing the [N(PPh3)2]ϩ cation with [PPh4]ϩ.
acetate were obtained commercially (Lancaster, Fluka or
Aldrich Chemical Companies) and used as supplied. Thallium
arene-1,2-dithiolates were made by reaction of thallium()
acetate and arenedithiol in methanol. The IR spectra were
measured on a Nicolet Impact 400 FT spectrometer, and FAB
mass spectra on an upgraded VG MS9 using a nitrobenzyl
alcohol matrix. The
1H NMR spectra were recorded at ambient
1
temperature using a Bruker AC 200 spectrometer, operating at
200.13 MHz, and at variable temperatures on a Bruker DPX
400 instrument at 400.13 MHz, using SiMe4 as internal refer-
ence. Elemental analyses were carried out at Heriot-Watt
University.
Differences in chemical shifts are also noted for the H NMR
resonances of aromatic and cyclopentadienyl hydrogens (see
Experimental section) of TlTiCp(bdt)2 5 (in CD2Cl2) and
TlTiCp(tdt)2 6 (in CDCl3) compared to those reported for the
respective ionic derivatives [PPh4][TiCp(bdt)2]12 and [NEt4]-
[TiCp(tdt)2]11 in the same solvents. These shifts support differ-
ing interactions between [Ti(η5-C5HnMe5 Ϫ n)(S2C6H3R)2]Ϫ and
Tlϩ or the large organo-phosphorus or nitrogen cations in
solution, and are consistent with TlI being co-ordinated to the
S-donor sites of the dithiolate ligands in contrast to non-co-
ordinating [N(PPh3)2]ϩ, [PPh4]ϩ or [NEt4]ϩ ions, as found in the
solid state. The NMR observations may indicate a structure
shown below in solution.
Preparations
Tl[Ti(ç5-C5Me5)(1,2-S2C6H4)2] 1. The compound TiCp*Cl3
(0.10 g, 3.5 × 10Ϫ4 mol) was dissolved in thf (4 cm3) 1.2-
(TlS)2C6H4 (0.39 g, 7.1 × 10Ϫ4 mol) was suspended in thf (5
cm3). The solution of TiCp*Cl3 was added to the Tl2bdt sus-
pension and the reaction mixture stirred overnight. Filtration
through Celite, followed by the removal of solvent in vacuo
afforded a dark purple solid. Crystallisation from CH2Cl2–light
petroleum yielded pure 1 (0.15 g, 65%). Further recrystallis-
ation from the same solvents afforded X-ray diffraction quality
crystals (Found: C, 39.4; H, 3.4. C22H23S4TiTl requires C, 39.5;
R
R
R
R
R
R′
1
Ti
Tl
R′
H, 3.4%). H NMR (CDCl3, 20 ЊC): δ 2.08 (s, 15 H, C5Me5),
S
S
S
6.97 (BBЈ part of AAЈBBЈ, JBA ϩ JBAЈ = 9.2, 4 H, H4,5 of C6H4),
7.39 (AAЈ part of AAЈBBЈ, JAB ϩ JABЈ = 9.2 Hz, 4 H, H3,6 of
C6H4); (CD2Cl2, 20 ЊC): δ 1.99 (s, 15 H, C5Me5), 6.91 (BBЈ part
of AAЈBBЈ, 4 H, H4,5 of C6H4); 7.30 (AAЈ part of AAЈBBЈ, 4 H,
H3,6 of C6H4); (CF3Cl–CD2Cl2, Ϫ119 ЊC): δ 6.90 (br, 4 H), 7.25
(br, 4 H). IR (KBr) cmϪ1: 3036w (CH str), 2901m (CH3 str),
1431s (C᎐C str), 1373s (CH3 def), 1020m, 736vs (CH def). FAB
MS, m/z (205Tl) significant ions: 879 (2, [M ϩ Tl]ϩ), 668 (16,
Mϩ), 667 (24), 533 (4, [M Ϫ Cp*]ϩ), 532 (5), 464 (2) 463 (1,
[M Ϫ Tl]ϩ), 205 (60, Tlϩ).
S
Conclusion
Thallium derivatives of monocyclopentadienylbis(arene-1,2-
dithiolato)titanium() anions containing pentamethyl-, mono-
methyl- and non-substituted -cyclopentadienyl ligands can be
prepared, and methylation of the rings does not markedly influ-
ence the stability of these compounds. The free anion [TiCp*-
(bdt)2]Ϫ, with [N(PPh3)2]ϩ as counter cation, in complex 7
adopts a structure in the crystalline state with an endo/exo
conformation of the two benzene-1,2-dithiolate ligands.
In the solid state, the related heterometallic derivative
TlTiCp*(bdt)2 1 contains thallium() ions unsymmetrically co-
ordinated to sulfur atoms of anions [TiCp*(bdt)2]Ϫ. There are
two different forms of the anion with endo/endo or endo/exo
conformation, respectively, and in both forms one TlI ion inter-
acts with two sulfur atoms of an endo dithiolate ligand. The TlI
associated closely with the endo/endo ligand (A) also shows
Tl[Ti(ç5-C5Me5)(3,4-S2C6H3CH3-1)2] 2. The compound
TiCp*Cl3 (0.090 g, 3.1 × 10Ϫ4 mol) was dissolved in thf (5 cm3)
and transferred via cannula to a suspension of Tl2tdt (0.37 g,
6.5 × 10Ϫ4 mol) in thf (5 cm3). The reaction mixture became
dark red in colour rapidly after mixing and was left stirring at
ambient temperature for 18 h. The reaction mixture was filtered
through Celite, removing precipitated TlCl and unreacted
Tl2tdt. The dark red solution was reduced to dryness in vacuo,
yielding a dark purple solid. The crude product was purified by
crystallisation from CH2Cl2–light petroleum, yielding pure 2
1584
J. Chem. Soc., Dalton Trans., 1998, Pages 1581–1586

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(0.070 g, 32%) (Found: C, 41.3; H, 3.8. C24H27S4TiTl requires C,
41.4; H, 3.8%). 1H NMR (CDCl3, 20 ЊC): δ 2.08 (s, 15 H,
C5Me5), 2.22 (s, 6 H, CH3), 6.85 (m, 2 H, H5 of C6H3), 7.23 (m,
2 H, H2 of C6H3), 7.27 (d, J 7 Hz, 2 H, H6 of C6H3).
Table 3 Crystallographic data for complexes 1 and 7ؒ3CH2Cl2
1
7ؒ3CH2Cl2
Formula
M
C22H23S4TiTl
667.91
C58H53NP2S4Tiؒ3CH2Cl2
1256.87
Tl[Ti(ç5-C5H4Me)(1,2-S2C6H4)2] 3. By a similar procedure to
that described above, TiCpЈCl3 (0.10 g, 4.3 × 10Ϫ4 mol) and
Tl2bdt (0.47 g, 8.6 × 10Ϫ4 mol) gave, after purification from thf–
light petroleum, 3 (0.08 g, 31%) (Found: C, 35.0; H, 2.3.
System
Space group
Triclinic
P1
Triclinic
P1
¯
¯
Temperature/K
a/Å
b/Å
c/Å
α/Њ
β/Њ
293
160
12.2824(9)
13.9012(10)
15.6661(12)
70.396(5)
68.067(8)
84.155(6)
2336.6(3)
4
1.899
7.594
9248
8014
11.473(3)
15.545(4)
16.778(6)
89.08(2)
88.04(2)
89.859(14)
2990.2(15)
2
1.396
0.644
10 398
10 377
0.068
1
C18H15S4TiTl requires C, 35.3; H, 2.4%). H NMR [(CD3)2SO,
20 ЊC]: δ 2.10 (s, 3 H, C5H4Me), 5.74 [AAЈ part of AAЈBBЈ
(≈t, J ≈ 5), 2 H, C5H4Me], 5.92 [BBЈ part of AAЈBBЈ (≈t, J ≈ 5),
2 H, C5H4Me], 6.82 (BBЈ part of AAЈBBЈ, JBA ϩ JBAЈ = 9.1 Hz,
4 H, H4,5 of C6H4), 7.22 (AAЈ part of AAЈBBЈ, 4 H, H3,6 of
C6H4).
γ/Њ
U/Å3
Z
Dc/g cmϪ3
µ(Mo-Kα)/mmϪ1
Data measured
Unique data
Rint
Tl[Ti(ç5-C5H4Me)(3,4-S2C6H3CH3-1)2] 4. Similarly, TiCpЈCl3
(0.10 g, 4.3 × 10Ϫ4 mol) and Tl2tdt (0.50 g, 8.8 × 10Ϫ4 mol) were
reacted in thf (5 cm3) at room temperature for 16 h. After puri-
fication from CH2Cl2–thf–light petroleum 4 was obtained as a
dark purple solid (0.1 g, 40%) (Found: C, 37.8; H, 3.1.
0.044
Observed data [I > 2σ(I)] 5095
R, wR2 (observed data)
6296
0.0470, 0.0839 0.0646, 0.1451
1
C20H19S4TiTl requires C, 37.6; H, 3.0%). H NMR (CDCl3,
20 ЊC): δ 2.26 (s, 6 H, CH3), 2.29 (s, 3 H, C5H4Me), 6.32
[AAЈ part of AAЈBBЈ (≈t, J ≈ 5), 2 H, C5H4Me], 6.47 [BBЈ
part of AAЈBBЈ (≈t, J ≈ 5), 2 H, C5H4Me], 6.84 (m, 2 H, H5 of
C6H3), 7.27 (m, 2 H, H2 of C6H3), 7.31 (d, J 8 Hz, 2 H, H6
of C6H3).
mounted in epoxy resin glue in a sealed, thin-walled glass capil-
lary under dry nitrogen. Crystals of 7 were found to be very
sensitive to solvent loss and a crystal was cut, mounted in Nujol
and vacuum grease on a glass fibre and placed quickly into a
cold stream of nitrogen gas on a Siemens P4 diffractometer at
160 K.20 Details of the crystal structure determinations of 1
and 7 are given in Table 3.
CCDC reference number 186/943.
See http://www.rsc.org/suppdata/dt/1998/1581/ for crystallo-
graphic files in .cif format.
Tl[Ti(ç5-C5H5)(1,2-S2C6H4)2] 5. Similarly, TiCpCl3 (0.10 g,
4.5 × 10Ϫ4 mol) and Tl2bdt (0.50 g, 9.1 × 10Ϫ4 mol) gave, after
purification from thf–light petroleum, 5 (0.10 g, 41%) as a dark
coloured solid (Found: C, 33.9; H, 2.0. C17H13S4TiTl requires C,
1
34.1; H, 2.2%). H NMR [(CD3)2SO, 20 ЊC]: δ 5.96 (s, 5 H,
C5H5), 6.82 (BBЈ part of AAЈBBЈ, JBA ϩ JBAЈ = 9.2 Hz, 4 H, H4,5
of C6H4), 7.22 (AAЈ part of AAЈBBЈ, 4 H, H3,6 of C6H4);
(CD2Cl2, 20 ЊC): δ 6.49 (s, 5 H, C5H5), 7.07 (BBЈ part of
AAЈBBЈ, 4 H, H4,5 of C6H4), 7.45 (AAЈ part of AAЈBBЈ, 4 H,
H3,6 of C6H4).
Acknowledgements
M. A. S. and G. M. R. thank Heriot-Watt University (for the
award of a University Studentship) and the EPSRC (for a
ROPA award), respectively. We also thank Dr. A. S. F. Boyd for
running variable-temperature NMR spectra.
Tl[Ti(ç5-C5H5)(3,4-S2C6H3CH3-1)2] 6. Similarly, TiCpCl3
(0.10 g, 4.5 × 10Ϫ4 mol) and Tl2tdt (0.55 g, 9.8 × 10Ϫ4 mol)
gave, after purification from CH2Cl2–light petroleum, 6 (0.10 g,
36%) as a dark coloured solid (Found: C, 36.0; H, 2.6.
References
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1
C19H17S4TiTl requires C, 36.5; H, 2.7%). H NMR (CDCl3,
20 ЊC): δ 2.27 (s, 6 H, CH3), 6.50 (s, 5 H, C5H5), 6.85 (m, 2 H, H5
of C6H3), 7.27 (m, 2 H, H2 of C6H3), 7.32 (d, J 8 Hz, 2 H, H6 of
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[N(PPh3)2][Ti(ç5-C5Me5)(1,2-S2C6H4)2] 7. Compound 1 (0.10
g, 1.5 × 10Ϫ4 mol) was dissolved in CH2Cl2 (10 cm3), [N(PPh3)2]-
Cl (0.085 g, 1.5 × 10Ϫ4 mol) was dissolved in CH2Cl2 (2 cm3).
The two solutions were combined and stirred at room tempera-
ture for 16 h. The reaction mixture was filtered through Celite
and the solvent removed in vacuo, yielding a dark red oily
material. Trituration with light petroleum, followed by crystal-
lisation from CH2Cl2–light petroleum gave dark red crystals,
containing solvated dichloromethane. Extensive drying under
vacuum gave pure, unsolvated 7 (0.11 g, 73%) (Found: C, 69.2;
H, 5.7; N, 1.3. C58H53NP2S4Ti requires C, 69.5; H, 5.3; N, 1.4%).
1H NMR (CDCl3, 20 ЊC): δ 1.90 (s, 15 H, C5Me5), 6.50 (BBЈ
part of AAЈBBЈ, JBA ϩ BAЈ = 9.1 Hz, 4 H, H4,5 of C6H4), 7.15 (AAЈ
part of AAЈBBЈ, 4 H, H3,6 of C6H4), 7.2–7.5 [complex, 30 H,
P(C6H5)3].
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tions with light petroleum at Ϫ15 ЊC. A single crystal of 1 was
J. Chem. Soc., Dalton Trans., 1998, Pages 1581–1586
1585

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Received 2nd February 1998; Paper 8/00890F
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J. Chem. Soc., Dalton Trans., 1998, Pages 1581–1586