Synthesis and structural characterisation of titanium(iv) thiolate compounds

Article abstract of DOI:10.1039/b006115h

Synthetic and structural studies have been performed for two thiolate complexes of titanium(iv). The reaction between Ti(NEt₂)₄ and 10 equivalents of C6F5SH at room temperature resulted in the formation of the ionic complex [Et₂NH₂]_i[Ti(SC₆F₅) ₅][SC₆F₅]₂. The related reaction between Ti(NEt₂)₄ and 4 equivalents of C₆F₅SH at room temperature, in the presence of a two electron donor ligand L (2,6-dimethylpyridine or tetrahydrothiophene), resulted in the isolation of the ionic complex [Et₂NH₂][Ti(SC₆F₅) ₄(NEt₂)]. However, if the reaction between Ti(NEt2)4 and 4 equivalents of C6F5SH is carried out without the addition of L, the first compound is formed rather than the second. The two new complexes have been characterised by X-ray crystallography. [Et₂NH₂]₃-[Ti(SC₆F₅) ₅][SC₆F₅]₂ is the first structurally characterised example of a five-co-ordinate homoleptic sulfur-bonded titanium complex. Both adopt similar sheet structures held together by π-π and C-F ...π interactions. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/b006115h

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Synthesis and structural characterisation of titanium(IV) thiolate
compounds
Claire J. Carmalt,*a Christopher W. Dinnage,a Ivan P. Parkin,a Andrew J. P. Whiteb and
David J. Williamsb
a Department of Chemistry, Christopher Ingold Laboratories, University College London,
20 Gordon Street, London, UK WC1H 0AJ. E-mail: c.j.carmalt@ucl.ac.uk
b Department of Chemistry, Imperial College of Science, Technology and Medicine,
South Kensington, London, UK SW7 2AY
Received 28th July 2000, Accepted 6th September 2000
First published as an Advance Article on the web 3rd October 2000
Synthetic and structural studies have been performed for two thiolate complexes of titanium(IV). The reaction
between Ti(NEt2)4 and 10 equivalents of C6F5SH at room temperature resulted in the formation of the ionic
complex [Et2NH2]3[Ti(SC6F5)5][SC6F5]2. The related reaction between Ti(NEt2)4 and 4 equivalents of C6F5SH at
room temperature, in the presence of a two electron donor ligand L (2,6-dimethylpyridine or tetrahydrothiophene),
resulted in the isolation of the ionic complex [Et2NH2][Ti(SC6F5)4(NEt2)]. However, if the reaction between
Ti(NEt2)4 and 4 equivalents of C6F5SH is carried out without the addition of L, the first compound is formed
rather than the second. The two new complexes have been characterised by X-ray crystallography. [Et2NH2]3-
[Ti(SC6F5)5][SC6F5]2 is the first structurally characterised example of a five-co-ordinate homoleptic sulfur-bonded
titanium complex. Both adopt similar sheet structures held together by π–π and C–F ؒ ؒ ؒ π interactions.
Titanium disulfide (TiS2) has attracted much technological
attention in the past decade because it is one of the most effect-
ive cathode materials in high-energy rechargeable batteries.1,2 In
addition, TiS2 films are used as a solid lubricant due to the weak
van der Waals interactions between adjacent layers of the TiS2
lattice.1,3 The conventional chemical vapour deposition (CVD)
approach to the synthesis of TiS2 films involves the reaction
of TiCl4 with H2S at 430–540 ЊC.4 More recently, the CVD
reactions between TiCl4 and organothiols (e.g. ButSH) at tem-
peratures in excess of 200 ЊC were reported to result in the
formation of highly pure TiS2.5 However, the aforementioned
CVD routes to TiS2 films depend on the mixing of two chemical
species in the gas phase which can give rise to a range of stoi-
chiometries in the final product.1 Accordingly, attention has
turned recently to the development of single-source precursors
to overcome this problem.1 The use of a single-source precursor
in a CVD process could also reduce toxic or malodorous waste.
However, only three TiS2 single-source precursors have been
synthesized and employed in deposition studies, namely
[TiCl4(HSR)2] [R = cyclohexyl (1) or cyclopentyl (2)]6 and
[Ti(SBut)4] 3.7,8 Compounds 1 and 2 resulted in the formation
of high quality TiS2 films via single-source CVD within the
temperature range 200–600 ЊC,6 although precursors with Ti–
Cl bonds are potentially corrosive to the metal substrate at
CVD temperatures.9 A preliminary study describing the CVD
of compound 3 observed the formation of amorphous TiS films
at temperatures between 130 and 200 ЊC.7 More recently, the
deposition of thin films of TiS2 from 3 was reported at temper-
atures in the range 110–350 ЊC.8 It has been suggested that the
formation of TiS may have resulted from hydrolysis of the films,
accounting for the loss of sulfur.
pound that has only been studied to a limited extent.10 Early
preparative routes to titanium thiolates involved the reaction
of [Ti(NRЈ2)4] (RЈ = Me or Et) and HSR (R = Me, Et or Pri)
resulting in the formation of complexes of the type [Ti(SR)4-
(HSR)x(NHRЈ2)y] 4 (where (x ϩ y) varied from 0.8 to 1.33).11
The first homoleptic titanium thiolate complex, namely [Ti-
(SC6F5)4] 5 was reportedly prepared via the reaction of TiCl4
with 4 equivalents of HSC6F5. However, the product was only
characterised by IR spectroscopy.12 More recently, a number of
titanium(IV) complexes with unidentate thiolate ligands have
been structurally characterised, examples of which include
[Ti(SC6HMe4-2,3,5,6)4] 6,13 [TiCl2(SBut)(Diars)] 7 [where Diars
is o-phenylenebis(dimethylarsine)],14 [Me2NH2][Ti2(µ-SMe)3-
(SMe)6] 8,15 [Ti3(µ-SMe)6(SMe)6] 9,15 [Ti(η5-C5H4SiMe3)2(SC6-
F5)2] 1016 and [Et4N]2[Ti(SPh)6].17
We have previously reported the synthesis and structural
characterisation of the homoleptic titanium thiolate [Et2-
NH2][Ti2(µ-SCH2Ph)3(SCH2Ph)6] 11 and pyrolysis studies.18 In
this paper, we report the synthesis and structures of two ionic
titanium(IV) thiolate complexes, [Et2NH2]3[Ti(SC6F5)5][SC6F5]2
12 and [Et2NH2][Ti(SC6F5)4(NEt2)] 13.
Results and discussion
Initial attempts to prepare neutral monomeric thiolates of
titanium involved the addition of 10 equivalents of pentafluoro-
benzenethiol (HSC6F5) to a toluene solution of Ti(NEt2)4 at
room temperature. An immediate change from orange to dark
red was observed and work-up of the reaction mixture yielded a
dark red solid. Crystallisation from CH2Cl2–hexanes mixtures
afforded a 75% yield of dark red crystalline 12. Analytical and
spectroscopic data for 12 are consistent with the formation of
[Et2NH2]3[Ti(SC6F5)5][SC6F5]2 rather than the neutral complex
[Ti(SC6F5)4] 5 (Scheme 1).
We are interested in developing homoleptic titanium(IV)
thiolate complexes as CVD precursors to TiS2. Homoleptic
titanium thiolate complexes should reduce the possibility of
contamination from species such as C or Cl in the resulting
films and address some of the foregoing problems. Further-
more, titanium thiolate complexes represent a class of com-
An X-ray analysis of crystals of complex 12 revealed the
structure to comprise the homoleptic penta(pentafluoro-
benzenethiolato)titanate(IV) complex anion shown in Fig. 1,
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J. Chem. Soc., Dalton Trans., 2000, 3500–3504
This journal is © The Royal Society of Chemistry 2000
DOI: 10.1039/b006115h

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Table 1 Selected bond distances (Å) and angles (Њ) for compounds 12
and 13
Compound 12
Compound 13
Ti–S(1)
Ti–S(2)
Ti–S(3)
Ti–S(4)
Ti–S(5)
2.386(1)
2.406(1)
2.350(2)
2.356(2)
2.357(2)
Ti–S(1)
Ti–S(2)
Ti–N
2.417(1)
2.427(1)
1.849(4)
S(3)–Ti–S(4)
S(3)–Ti–S(5)
S(4)–Ti–S(5)
S(3)–Ti–S(1)
S(4)–Ti–S(1)
S(5)–Ti–S(1)
S(3)–Ti–S(2)
S(4)–Ti–S(2)
S(5)–Ti–S(2)
S(1)–Ti–S(2)
115.52(7)
126.47(7)
117.14(6)
88.22(5)
92.24(5)
98.65(5)
84.76(5)
89.10(5)
87.07(5)
172.73(6)
N–Ti–S(1)
N–Ti–S(2)
S(1)–Ti–S(1A)
S(1)–Ti–S(2)
S(1)–Ti–S(2A)
S(2A)–Ti–S(2)
119.86(3)
105.90(3)
120.27(6)
83.39(3)
80.92(3)
148.20(5)
Fig. 1 The molecular structure of the anion in the structure of
complex 12, showing the weak intramolecular C–F ؒ ؒ ؒ π interaction
(a); the F ؒ ؒ ؒ π distance is 3.43 Å and the C–F ؒ ؒ ؒ π angle 144Њ. Only
the titanium and sulfur atoms have been labelled for clarity.
Scheme 1
together with two pentafluorobenzenethiolate monoanions
and three diethylammonium monocations. The geometry at
titanium is distorted trigonal bipyramidal, with S(3), S(4) and
S(5) forming the equatorial plane, the titanium lying 0.13 Å out
of this plane in the direction of one of the axial sulfur
atoms [S(1)]. The angles subtended at the metal centre by the
equatorial atoms are in the range 115.5(1) to 126.5(1)Њ, and
the two axial sulfur atoms subtend an angle of 172.7(1)Њ at the
metal centre (Table 1). The Ti–S bond lengths fall into two
distinct groups with those to the equatorial sulfur atoms
[2.350(2)–2.357(2) Å] being ca. 0.04 Å shorter than those to the
axial ones [2.386(1) and 2.406(1) Å], the shorter of these two
axial bonds being to S(1) (the sulfur that the titanium is dis-
placed towards, see above). The Ti–S bonds observed in the
present structure are similar to those in 6 [average Ti–S
2.361(2) Å]13 and 7 [average Ti–S 2.332(3) Å],14 and to the
Fig. 2 View, in parallel projection down the crystallographic b axis, of
the packing of the anions in complex 12, showing their paddle-like
conformation and their interleaving and linking via π–π and C–F ؒ ؒ ؒ π
interactions to form two-dimensional sheets. The centroid–centroid
and mean interplanar separations (Å) are (b) 3.68, 3.51 and (c) 3.76,
3.45; for the C–F ؒ ؒ ؒ π interaction (d) the F ؒ ؒ ؒ π distance is 3.24 Å
and the C–F ؒ ؒ ؒ π angle is 143Њ; the angle subtended at the S(2) ring
centroid by the vectors b and d is 159Њ.
of the ortho fluorine atoms of the S(1) based C6F5 ring to the
S(5) ring (interaction a in Fig. 1).
It is interesting that four of the five SC6F5 units [those associ-
ated with S(1), S(2), S(3) and S(5)] are oriented such that their
planes are aligned essentially orthogonally to the crystallo-
graphic 010 plane [maximum inclination 14Њ for the S(2) ring]
creating a paddle-wheel-like motif, i.e. all of the Ti–S–Ar bends
are in the same sense. The remaining ring, based on S(4), is
nearly parallel to the 010 plane (inclined by ca. 27Њ). This
paddle-wheel motif facilitates the interleaving of adjacent com-
plexes which are cemented together by π–π stacking interactions
between the S(1) ring in one complex and the S(2) ring in the
next (interaction b in Fig. 2) and also between the S(3) and S(5)
rings in neighbouring complexes (interaction c in Fig. 2); the
S(1)/S(2) and S(3)/S(5) pairs of rings are inclined by 4 and 9Њ
respectively. These interactions combine to form an extended
two-dimensional sheet of complex anions whose upper and
lower surfaces are bounded by the S(4) rings that are not
involved in the aformentioned π–π stacking. This arrangement
is further stabilised by a C–F ؒ ؒ ؒ π interaction (d in Fig. 2)
terminal Ti–S bond lengths in 8 [2.321(1)–2.362(1) Å],15
9
[Ti–S 2.3134(7)–2.3177(7) Å],15 and 11 [Ti–S 2.3308(9)–
2.4090(10) Å].18 However, as expected, the foregoing Ti–S bond
distances are shorter than those reported for bridging thiolate
ligands, for example in 11 the bridging Ti–S bond distances
span the range 2.513(1)–2.561(1) Å.18 It is also worth noting
that the Ti–S bond distances in 12 are also shorter than those
observed in [Ti(η5-C5H4SiMe3)2(SC6F5)2] 10 [Ti–S 2.431(2) and
2.438(2) Å] as a result of the trimethylsilylcyclopentadienyl
groups in 10.16 The rotations about the Ti–S bonds are such
that the C6F5 rings attached to two of the sulfur atoms in the
equatorial plane [S(4) and S(5)] are oriented “above” this plane,
with that attached to S(3) “below”. This overall conformation
is, in part, stabilised by a weak C–F ؒ ؒ ؒ π interaction19 from one
J. Chem. Soc., Dalton Trans., 2000, 3500–3504
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Fig. 3 Part of one of the N–H ؒ ؒ ؒ S linked cation/anion hydrogen
bonded chains present in the crystals of complex 12. N ؒ ؒ ؒ S, H ؒ ؒ ؒ S
distances (Å) and N–H ؒ ؒ ؒ S angles (Њ); (e) 3.23, 2.38, 158; ( f ) 3.27,
2.42, 156; (g) 3.30, 2.41, 167; (h) 3.38, 2.60, 145; (i) 3.32, 2.45, 163 and
(j) 3.27, 2.39, 166. The N–H ؒ ؒ ؒ F interaction (k) has N ؒ ؒ ؒ F, H ؒ ؒ ؒ F
3.10, 2.47 Å and N–H ؒ ؒ ؒ F 127Њ.
between one of the fluorine atoms of an S(3) ring to the
“opposite” face of the π-stacked S(2) ring.
The space between parallel anionic two-dimensional sheets
is occupied by the three unique [Et2NH2]ϩ cations and two
[C6F5S]Ϫ anions. These are linked via N–H ؒ ؒ ؒ S hydrogen bonds
to form a chain that extends along the crystallographic c direc-
tion, utilising all six of the available donor N–H hydrogen
atoms (interactions e to j in Fig. 3). These cation/anion chains
are linked to the anionic sheets by weak C–F ؒ ؒ ؒ π interactions
from a fluorine on one of the [C6F5S]Ϫ rings of the chain to one
of the bounding S(4) rings of the sheet; the F ؒ ؒ ؒ π distance
is 3.32 Å, the C–F ؒ ؒ ؒ π angle is 128Њ and the F ؒ ؒ ؒ π vector is
inclined by ca. 71Њ to the S(4) ring plane.
Fig. 4 The molecular structure of the anion in the structure of
complex 13, showing the highly distorted trigonal bipyramidal/square
pyramidal co-ordination at titanium. Only the titanium and sulfur
atoms have been labelled for clarity.
this plane are 119.9(1) and 120.3(1)Њ (Table 1). The “axial”
sulfur atoms subtend an angle of 148.2(1)Њ at the metal
centre, producing a substantially greater distortion in the co-
ordination geometry than is observed in 12 [172.7(1)Њ]. Indeed,
the geometry in 13 could be considered as being intermediate
between trigonal bipyramidal and square pyramidal, with in
the latter case the diethylamino nitrogen atom occupying the
apical position. The Ti–S bond lengths exhibit an expected dif-
ference between those in axial [2.427(1) Å, S(2)] and equatorial
positions [2.417(1) Å, S(1)]. These distances are both signifi-
cantly longer than those in 12 but the difference is noticeably
less and may reflect the trend towards square pyramidal co-
ordination. The Ti–N bond length of 1.849(4) Å is short, indi-
cating a degree of partial double bond character, an assignment
reinforced by the trigonal planar geometry of the nitrogen
centre [the angles at nitrogen are 117.3(4), 121.3(2) and
121.3(2)Њ]. The Ti–N bond distance is similar to those found in
related amido complexes such as [Ti(NEt2)2(PhNNNPh)2] (Ti–
NEt2 1.883 Å).20 The trigonal plane of the nitrogen atom is
rotated by ca. 18Њ out of the equatorial co-ordination plane,
and there is a weak intramolecular C–H ؒ ؒ ؒ F interaction
between one of the terminal methyl hydrogen atoms of the
diethylamino substituent and the proximal ortho fluorine atom
on the S(1) ring [C ؒ ؒ ؒ F, H ؒ ؒ ؒ F distances 3.09, 2.43 Å;
C–H ؒ ؒ ؒ F angle 126Њ].
The rotations about the Ti–S bonds are again of interest,
with all of the SC6F5 ligands being bent towards the diethyl-
amino ligand (or alternatively, in the context of a square
pyramidal geometry, away from the four basal sulfur atoms).
This geometry results in the creation of a cleft within which the
diethylammonium cation is located. The cation is positioned
such that the two ammonium hydrogen atoms are directed
towards S(1) and S(1A), indicating possible weak N–H ؒ ؒ ؒ S
hydrogen bonding interactions [N ؒ ؒ ؒ S, H ؒ ؒ ؒ S distances (Å)
and N–H ؒ ؒ ؒ S angles (Њ); 3.38, 2.60, 146 and 3.59, 2.79, 147
respectively].† As was the case for four of the five SC6F5 rings
in 12, here all four are oriented essentially orthogonally to
the crystallographic ac plane [the maximum deviation from
orthogonal being ca. 13 Њ for the S(2) ring] and again adopt a
paddle-wheel-like conformation, the Ti–S–Ar bends all being
It is interesting to compare the structure of complex 12 with
those of 7 and 11. A similar synthetic methodology was used
for the preparation of 7 and 11 in which Ti(NEt2)4 was treated
with 10 equivalents of HSR (7, R = Me;15 11, R = CH2Ph18).
However, in contrast to 12, this results in the formation of
binuclear face-sharing octahedral complexes.
1
The H NMR spectrum of complex 12 recorded at room
temperature (CD2Cl2) consists of a triplet in the methyl region
and a quartet in the methylene region, corresponding to the
[Et2NH2]ϩ cations. The chemical shifts in the 19F NMR spec-
trum were similar to those reported for the SC6F5 group in
other perfluorophenyl thiolate derivatives and consisted of three
multiplets at δ Ϫ132.9, Ϫ160.9 and Ϫ165.3.16 This suggests that
12 exhibits fluxional behaviour between the [Ti(SC6F5)5]Ϫ anion
and the [SC6F5]Ϫ anions in solution since no peaks are observed
for the [SC6F5]Ϫ anions in 12.
With a view to developing a neutral monomeric titanium(IV)
thiolate, it was decided to introduce a two electron donor lig-
and, L [2,6-dimethylpyridine or tetrahydrothiophene (C4H8S)],
into the reaction and to limit the amount of thiol present.
Accordingly, Ti(NEt2)4 was treated with 4 equivalents of
HSC6F5, in the presence of 2,6-dimethylpyridine at room tem-
perature (Scheme 1). A dark red crystalline product (13) was
obtained in a 65% yield by diffusion of an overlayer of hexanes
into a saturated CH2Cl2 solution of 13. Analytical and spectro-
scopic data are consistent with the ionic species [Et2NH2]-
[Ti(SC6F5)4(NEt2)] as shown by the crystal structure analysis,
but not with the expected complex [Ti(SC6F5)4(L)x] 14.
The single crystal structure determination of complex 13
reveals a structure that is very similar to that of the complex
anion in 12 but with one of the pentafluorobenzenethiolate lig-
ands replaced by a diethylamino unit to give the C2 symmetric
diethylammonium salt of (diethylamido)tetra(pentafluoro-
benzenethiolato)titanate(IV) (Fig. 4). The geometry at titanium
is again distorted trigonal bipyramidal with S(1), S(1A) and N
occupying the equatorial sites. The equatorial plane, including
the titanium atom, is perfectly flat, a geometric consequence
of the twofold axis that passes along the Ti–N bond and bisects
the S(1)–Ti–S(1A) angle; the unique angles at titanium within
† The two different geometries are a consequence of the cation being
disordered about the crystallographic twofold axis.
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J. Chem. Soc., Dalton Trans., 2000, 3500–3504

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their low volatility precluded thin film growth by CVD. However,
compounds 12 and 13 can serve as precursors to TiS2 via a
novel thio ‘sol–gel’ methodology, the details of which will be
described in a future publication.22
Experimental
General procedures
All manipulations were performed under a dry, oxygen-free
dinitrogen atmosphere using standard Schlenk techniques or in
a Mbraun Unilab glove box. All solvents were distilled from
appropriate drying agents prior to use (sodium–toluene, THF
23
and hexanes; CaH2 for CH2Cl2) and Ti(NEt2)4 was prepared
by literature methods. All other reagents were procured com-
mercially from Aldrich and used without further purification.
Microanalytical data were obtained at University College
London (UCL).
Physical measurement
1H and 13C NMR spectra were recorded on Brüker AMX300 or
Fig. 5 View of part of one of the anionic two-dimensional sheets of
π–π, C–F ؒ ؒ ؒ π and F ؒ ؒ ؒ π linked complexes present in the structure
of complex 13. The π–π interaction (a) has centroid–centroid and mean
DRX500 spectrometers at UCL, referenced to CD2Cl2, which
1
was degassed and dried over molecular sieves prior to use; H
interplanar separations of 3.49 and 3.32
Å respectively. F ؒ ؒ ؒ π
and 13C chemical shifts are reported relative to SiMe4 (δ 0.00).
Mass spectra (CI) were run on a micromass ZABSE instru-
ment, and IR spectra on a Nicolet 205 instrument. Melting
points were obtained in sealed glass capillaries under nitrogen
and are uncorrected.
distances (Å), C–F ؒ ؒ ؒ π angles (Њ): (b) 3.09, 135; (c) 3.26, 152; (d)
centroid–centroid, mean interplanar separation, and F ؒ ؒ ؒ π distance
4.57, 3.23 and 3.35 Å respectively.
in the same sense. As can be seen in Fig. 5, this conformation
again facilitates the interleaving of the rings of adjacent com-
plexes to form a two-dimensional sheet in the crystallographic
ac plane. This arrangement is stabilised by a combination of
π–π (a), C–F ؒ ؒ ؒ π (b and c) and F ؒ ؒ ؒ π (d) interactions, with
the “upper” and “lower” surfaces being dominated by the co-
ordinated and cationic NEt2 units. There are in addition, how-
ever, short non-bonded F ؒ ؒ ؒ F contacts (2.76 Å) between a
meta fluorine atom of the S(1) rings in one sheet and their
counterparts on the S(2) rings in the next.
Treatment of Ti(NEt2)4 with an excess of tetrahydrothio-
phene (C4H8S) in toluene solution, followed by the addition
of four equivalents of HSC6F5, resulted, after work-up, in the
formation of a dark red crystalline solid. Analytical and spec-
troscopic data were again consistent with the formation of
complex 13 rather than the anticipated product 14. The two-
electron donor ligands (L) may be involved in the reaction
leading to the formation of 13, however, no product containing
L was isolated in either reaction. It is interesting that 5 was
reported to show no reactivity towards common donor ligands
such as pyridine or PPh3.12
In an attempt to isolate the neutral homoleptic species [Ti-
(SC6F5)4]n, compound 13 was heated in vacuo (100 ЊC, 10Ϫ3
mmHg). It was expected that 13 would lose amine and thiol
to produce [Ti(SC6F5)4]n as has been observed in some related
metal thiolate salts.21 However, prolonged heating of 13
resulted in an insoluble brown solid (15). Analytical data for
15 show the presence of nitrogen in the complex suggesting that
13 has not lost all the amine. It is likely that some form of
polymer was produced as a result of heating 13.
Preparations
[Et2NH2]3[Ti(SC6F5)5][SC6F5]2 12. Method 1. Pentafluoro-
benzenethiol (2.25 cm3, 16.90 mmol) was added dropwise to an
orange solution of Ti(NEt2)4 (0.6 cm3, 1.66 mmol) in toluene
(20 cm3) at room temperature with stirring. The solution turned
dark red immediately on addition of the thiol. The mixture was
stirred for 2 hours at room temperature and then the solvent
was removed in vacuo. The resulting dark red oil was dissolved
in toluene (20 cm3) and filtered through Celite to give a dark red
solution. Cooling to Ϫ20 ЊC overnight afforded a 75% yield of
red crystalline complex 12. Single crystals suitable for crystal-
lography were obtained by dissolving the solid in CH2Cl2
(4 cm3) and overlaying this solution with hexanes (20 cm3).
Solvent diffusion at room temperature over a period of days
afforded dark red needles of 12 (mp 108–112 ЊC).
Method 2. HSC6F5 (0.44 cm3, 3.30 mmol) was added drop-
wise to an orange solution of Ti(NEt2)4 (0.3 cm3, 0.83 mmol)
in toluene (20 cm3) at room temperature with stirring. The
solution turned dark red immediately on addition of the thiol.
The mixture was treated as above. Calc. for C54H36F35N3S7Ti:
C, 38.9; H, 2.16; N, 2.52. Found C, 40.06; H, 2.28; N, 2.84%.
1H NMR (CD2Cl2): δ 1.49 (t, 18H, NCH2CH3), 3.29 (q, 12H,
NCH2CH3) and 8.33 (s, 6H, NH2). 13C-{1H} NMR (CD2Cl2):
δ 11.2 (NCH2CH3), 42.0 (NCH2CH3), 121, 137, 145 (SC6F5).
19F-{1H} NMR (CD2Cl2, reference CFCl3): δ Ϫ132.9 (m, 10F,
F2,6 of C6F5), Ϫ160.9 (m, 5F, F4 of C6F5) and Ϫ165.3 (m, 10F,
F3,5 of C6F5).
Finally, Ti(NEt2)4 was treated with four equivalents of
HSC6F5 but without the addition of co-ordinating ligands. A
dark red crystalline solid was isolated, the H NMR of which
[Et2NH2][Ti(SC6F5)4(NEt2)] 13. Method 1. 2,6-Dimethyl-
pyridine (0.39 cm3, 3.34 mmol) was added to an orange solution
of Ti(NEt2)4 (0.6 cm3, 1.66 mmol) in toluene (20 cm3) at
room temperature. Pentafluorobenzenethiol (0.88 cm3, 6.60
mmol) was added dropwise and the solution turned dark red
immediately. After stirring for 2 hours at room temperature
the solvent was removed in vacuo. The resulting dark red oil
was dissolved in toluene (20 cm3) and filtered through Celite to
give a dark red solution. Cooling to Ϫ20 ЊC overnight resulted
in the formation of a 65% yield of crystalline red complex 13.
Single crystals suitable for crystallography were obtained
by dissolving the solid in CH2Cl2 (4 cm3) and overlaying this
1
indicated that complex 12 had formed rather than 13 as was
initially expected. This suggests that the presence of L in the
reaction mixture to produce 13 does affect the final product
obtained.
In summary, two novel ionic thiolate complexes of
titanium(IV), namely [Et2NH2]3[Ti(SC6F5)5][SC6F5]2 12 and
[Et2NH2][Ti(SC6F5)4(NEt2)] 13, have been synthesized and
structurally characterised. Both adopt similar sheet structures
held together by π–π and C–F ؒ ؒ ؒ π interactions. Unfortunately,
J. Chem. Soc., Dalton Trans., 2000, 3500–3504
3503

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solution with hexanes (20 cm3). Solvent diffusion over a period
of days at room temperature afforded dark red crystals
(mp 148–150 ЊC).
Acknowledgements
We thank EPSRC (GR/M11981) for financial support and a
studentship (C.W.D.). C.J.C. is also grateful to the Royal
Society for a Dorothy Hodgkin fellowship and additional
support and London University Central Research Fund for
financial support.
Method 2. Tetrahydrothiophene (0.38 cm3, 3.34 mmol) was
added to an orange solution of Ti(NEt2)4 (0.6 cm3, 1.66 mmol)
in toluene (20 cm3) at room temperature. Subsequent treatment
as above resulted in the formation of a 65% yield of a crystal-
line red solid. Calc. for C32H22F20N2S4Ti: C, 38.79; H, 2.22; N,
1
2.83. Found C, 38.83; H, 2.10; N, 3.17%. H NMR (CD2Cl2):
References
δ 1.05 (t, 6H, NCH2CH3), 1.50 (t, 6H, H2NCH2CH3), 3.45
(q, 4H, H2NCH2CH3), 4.34 (q, 4H, NCH2CH3) and 7.30 (s, 2H,
H2NCH2CH3). 13C-{1H} NMR (CD2Cl2): δ 11.6 (NCH2CH3),
12.7 (H2NCH2CH3), 43.4 (H2NCH2CH3), 49.7 (NCH2CH3),
121, 147, 146 (SC6F5). 19F-{1H} NMR (CD2Cl2, reference
CFCl3): δ Ϫ132.5 (m, 8F, F2,6 of C6F5), Ϫ160.5 (m, 4F, F4 of
C6F5) and Ϫ164.9 (m, 8F, F3,5 of C6F5).
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X-Ray crystallography
Crystals of complexes 12 and 13 were grown from CH2Cl2–
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9 C. H. Winter, T. S. Lewkebandara, J. W. Proscia and A. L.
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Crystal data for complex 12. [C4H12N]3[C30F25S5Ti][C6F5S]2,
M = 1664.2, monoclinic, space group P21/c (no. 14), a =
9.953(1), b = 31.429(2), c = 21.014(2) Å, β = 91.58(1)Њ, V =
6571(1) Å3, Z = 4, µ(Cu-Kα) = 4.48 mmϪ1, T = 183 K; deep red
platy needles, Siemens P4/RA diffractometer, ω scans, 9610
independent reflections. The structure was solved by direct
methods and the non-hydrogen atoms were refined anisotropic-
ally using full matrix least squares based on F2 to give R1 =
0.054, wR2 = 0.123 for 6536 independent observed absorption
corrected reflections [|Fo| > 4σ(|Fo|)], 2θ р 120Њ.
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19 For an overview of interactions involving an acceptor C6F6 group
see I. Alkorta, I. Rozas and J. Elguero, J. Org. Chem., 1997, 62,
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20 I. A. Guzei, L. M. Liable-Sands, A. L. Rheingold and C. H. Winter,
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Crystal data for complex 13. [C4H12N][C28H10F20NS4Ti], M =
990.7, monoclinic, space group C2/c (no. 15), a = 15.200(1),
b = 17.615(1), c = 14.117(2) Å, β = 91.18(1)Њ, V = 3779.1(7) Å3,
Z = 4 (the complex has crystallographic C2 symmetry), µ(Cu-
Kα) = 5.18 mmϪ1, T = 193 K; deep red blocks, Siemens P4/RA
diffractometer, ω scans, 3093 independent reflections. The
structure was solved and refined as above to give R1 = 0.055,
wR2 = 0.143 for 2598 independent observed absorption
corrected reflections [2θ р 128Њ].
CCDC reference number 186/2175.
See http://www.rsc.org/suppdata/dt/b0/b006115h/ for crystal-
lographic files in .cif format.
23 D. C. Bradley and I. M. Thomas, J. Chem. Soc., 1960, 82, 3857.
3504
J. Chem. Soc., Dalton Trans., 2000, 3500–3504