Alkyloxy- and aryloxy-titanocenes: Synthesis, solid-state structure and cyclic voltammetric studies

Article abstract of DOI:10.1016/j.jorganchem.2008.07.016

Alkyloxy- and aryloxy-functionalized titanocenes of type [Ti](Cl)(OR) (R = Me (2), CH₂PPh₂ (3), CH₂Fc (4), C₆H₅ (5), C₆H₄-4-C{triple bond, long}N (6), C₆H₄-4-NO₂ (7), C₆H₄-4-Me (8), C₆H₄-4-OMe (9), C₆H₄-4-C(O)Me (10), C₆H₄-4-CO₂Me (11), C₆H₄-3-NO₂ (12); [Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; Fc = (η⁵-C₅H₄)(η⁵-C₅H₅)Fe) were synthesized by the reaction of [Ti]Cl₂ (1) with ROH in a 1:1 molar ratio and in presence of Et₂NH. Diaryloxy-titanocenes (e.g., [Ti](OC₆H₄-4-NO₂)₂ (13)) are accessible, when the ratio of 1 and ROH is changed to 1:2. This synthesis methodology also allowed the preparation of dinuclear complexes of composition ([Ti](Cl))₂(μ-OC₆H₄O) (14) and ([Ti](Cl)(μ-OC₆H₄-4))₂ (15) by the reaction of 1 with hydroquinone or 1,1′-dihydroxybiphenyl in a 2:1 stoichiometry. Cyclic voltammetric studies show the characteristic [Ti(IV)/Ti(III)] reductions. It was found that the potentials of the alkyloxy titanocenes 2-4 do not differ, while for the aryloxy-titanocenes 5-15 the reduction potentials correlate linearly with the σ_p/m Hammett substituent constants showing a strong influence of the substituents on the electron density at titanium. The structures of titanocenes 4, 5, 9, and 11-13 in the solid state are reported. Typical for these organometallic sandwich compounds is a distorted tetrahedral coordination geometry around titanium with D1-Ti-D2 angles (D1, D2 = centroids of the cyclopentadienyl ligands) of ca. 130 °. In comparison to FcCH₂O-functionalized 4, for the aryloxy-titanocenes 5, 9, and 11-13 a significant larger Ti-O-C angle was found confirming electronic interactions between the titanium atom and the appropriate aryl group.

Full text of DOI:10.1016/j.jorganchem.2008.07.016

Journal of Organometallic Chemistry 693 (2008) 3213–3222
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Alkyloxy- and aryloxy-titanocenes: Synthesis, solid-state structure and cyclic
voltammetric studies
*
Stefan Köcher, Bernhard Walfort, Gerd Rheinwald, Tobias Rüffer, Heinrich Lang
Technische Universität Chemnitz, Fakultät für Naturwissenschaften, Institut für Chemie, Lehrstuhl für Anorganische Chemie, Straße der Nationen 62, 09111 Chemnitz, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 15 May 2008
Received in revised form 10 July 2008
Accepted 14 July 2008
Available online 22 July 2008
Alkyloxy- and aryloxy-functionalized titanocenes of type [Ti](Cl)(OR) (R = Me (2), CH2PPh2 (3), CH2Fc (4),
C6H5 (5), C6H4-4-C„N (6), C6H4-4-NO2 (7), C6H4-4-Me (8), C6H4-4-OMe (9), C6H4-4-C(O)Me (10), C6H4-4-
CO2Me (11), C6H4-3-NO2 (12); [Ti] = (g g g
5-C5H4SiMe3)2Ti; Fc = ( 5-C5H4)( 5-C5H5)Fe) were synthesized by
the reaction of [Ti]Cl2 (1) with ROH in a 1:1 molar ratio and in presence of Et2NH. Diaryloxy-titanocenes
(e.g., [Ti](OC6H4-4-NO2)2 (13)) are accessible, when the ratio of 1 and ROH is changed to 1:2. This
synthesis methodology also allowed the preparation of dinuclear complexes of composition ([Ti](Cl))2-
Dedicated to Professor Dr. Ch. Elschenbroich
on the occasion of his 70th birthday.
(l-OC6H4O) (14) and ([Ti](Cl)(l
-OC6H4-4))2 (15) by the reaction of 1 with hydroquinone or 1,10-dihy-
droxybiphenyl in a 2:1 stoichiometry.
Cyclic voltammetric studies show the characteristic [Ti(IV)/Ti(III)] reductions. It was found that the
potentials of the alkyloxy titanocenes 2–4 do not differ, while for the aryloxy-titanocenes 5–15 the reduc-
tion potentials correlate linearly with the rp/m Hammett substituent constants showing a strong influ-
ence of the substituents on the electron density at titanium.
The structures of titanocenes 4, 5, 9, and 11–13 in the solid state are reported. Typical for these organo-
metallic sandwich compounds is a distorted tetrahedral coordination geometry around titanium with
D1–Ti–D2 angles (D1, D2 = centroids of the cyclopentadienyl ligands) of ca. 130 °. In comparison to
FcCH2O-functionalized 4, for the aryloxy-titanocenes 5, 9, and 11–13 a significant larger Ti–O–C angle
was found confirming electronic interactions between the titanium atom and the appropriate aryl group.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords:
Titanocene
Alkyloxy
Aryloxy
Cyclic voltammetry
Hammett parameter
1. Introduction
sandwich complexes [Ti](Cl)(OR) (R = Me, CH2PPh2, CH2Fc, C6H5,
C6H4-4-C„N, C6H4-4-NO2, C6H4-4-Me, C6H4-4-OMe, C6H4-4-
Titanium compounds play an important role in industrial pro-
cesses including homogeneous catalysis, for example, polymeriza-
C(O)Me, C6H4-4-CO2Me, C6H4-3-NO2; [Ti] = (
Fc = (
5-C5H4)( 5-C5H5)Fe) and [Ti](OC6H4-4-NO2)2 as well as the
homobimetallic titanocenes ([Ti](Cl))2( -OC6H4O) and ([Ti](Cl)-
-OC6H4-4))2, respectively. In the latter molecules two [Ti]Cl
moieties are connected by either a OC6H4O or a OC6H4C6H4O bridg-
ing unit.
g
5-C5H4SiMe3)2Ti;
g
g
tion of
a-olefins [1], hydroboration [2], oxidation [3], and carbonyl
l
coupling reactions. [4,5]. For the development and optimization of
homogeneous catalysts it is necessary to fine-tune the electronic
properties of the active metal atom by appropriately functionalized
ligands, whereby an electronic interaction between the substitu-
ent(s) via the ligand(s) with the metal center is essential [6].
Although bis(cyclopentadienyl)titanium-oxo compounds are
known for quite some years, the primary focus has been directed
on their preparation [8–15]. However, only less is known about
the electrochemical behavior of alkyloxy- and aryloxy-titanocenes
[7]. In general, titanium–oxygen bonds are with ca. 1.85 Å [8,9]
unusual short, and the Ti–O–Ti bond angles are with ꢀ170 ° almost
(l
2. Results and discussion
2.1. Synthesis and spectroscopy
General synthetic methodologies for the preparation of alkyl-
oxy- and aryloxy-functionalized titanocenes of type (
Ti(Cl)2ꢁn(OR)n (R = alkyl, aryl; n = 1, 2) include the reaction of
5-C5H5)2TiCl2 with acidic compounds such as alcohols or carbox-
ylic acids in presence of a base [8, 11]. Care must be taken since
from (
5-C5H5)2TiCl2 one of the cyclopentadienyl annulenes can
be replaced by a RO ligand to give the half-sandwich complexes
5-C5H5)Ti(Cl)3ꢁn(OR)n (n = 1, 2, 3) depending on the reaction
g
5-C5H5)2-
linear [10]. These data suggest a partial Ti–O p-bond which should
(g
facilitate an electronic interaction between titanium and the
respective terminal groups R with their diverse functionalities [9].
We here report on the synthesis, characterization, structural
features and electrochemical behavior of the mononuclear bent
g
(g
conditions applied [12]. As suitable base most commonly Et3N is
used but inorganic bases like NaHCO3 and NaNH2 can also be
* Corresponding author. Tel.: +49 371 531 21210; fax: +49 371 531 21219.
E-mail address: heinrich.lang@chemie.tu-chemnitz.de (H. Lang).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.07.016

3214
S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 3213–3222
Table 1
considered [8–12]. Another straightforward access to alkyloxy- and
aryloxy-titanocenes is given by the reaction of methyl-titanocene
chlorides or dimethyl-titanocenes with alcohols or carboxylic acids,
whereby methane is evolved as only further product [13,14]. The
formation of quinonide bridged homodinuclear titanocenes can
Synthesis of 2–12 from 1 and ROH
Compound
R
Yielda (%)
2
3
4
Me
95
74
89
CH2PPh2
CH2Fcb
be realized by the reaction of titanium(III) precursors such as (g5
-
C5Me5)2TiCl with benzoquinone as reported by Roesky and cowork-
ers [15].
5
6
7
8
C6H5
87
96
84
95
94
95
98
91
C6H4-4-C„N
C6H4-4-NO2
C6H4-4-Me
C6H4-4-OMe
C6H4-4-COMe
C6H4-4-CO2Me
C6H4-3-NO2
Following the first synthesis approach we prepared a series of
different alkyloxy- and aryloxy-titanocene chlorides of type [Ti]
(Cl)(OR) (R = Me (2), CH2PPh2 (3), CH2Fc (4), C6H5 (5), C6H4-4-
C„N (6), C6H4-4-NO2 (7), C6H4-4-Me (8), C6H4-4-OMe (9), C6H4-
9
10
11
12
4-C(O)Me (10), C6H4-4-CO2Me (11), C6H4-3-NO2 (12); [Ti] = (g5
-
C5H4SiMe3)2Ti; Fc = (g g
5-C5H4)( 5-C5H5)Fe) by treatment of [Ti]Cl2
a
Based on 1.
(1) with alcohols ROH (R = Me, CH2PPh2, CH2Fc, C6H5, C6H4-4-
C„N, C6H4-4-NO2, C6H4-4-Me, C6H4-4-OMe, C6H4-4-C(O)Me,
C6H4-4-CO2Me, C6H4-3-NO2) in a 1:1 molar ratio in diethyl ether
at room temperature (Table 1, Reaction 1). Instead of NEt3 more
basic HNEt2 was chosen because this secondary amine allowed
shorter reaction times, resulted in higher yields of titanocenes 2–
12, and due to the formation of the less soluble ammonium salt
[Et2NH2]Cl a more efficient purification is permitted (Section 4).
b
Fc = (g g
5-C5H5)( 5-C5H4)Fe.
In the synthesis of [Ti](Cl)(OC6H4-4-NO2) (7) always reaction
mixtures were obtained consisting the mono-aryloxy-titanocene
chloride 7 and traces of the appropriate bis(aryloxy) titanium com-
plex [Ti](OC6H4-4-NO2)2 (13) (Section 4). This is inexplicable be-
cause in all other cases (vide supra) even by using an excess of
the alcohol component the formation of mono-alkyloxy- and -aryl-
oxy-titanocenes was favored over the dialcoholate species. Pure 7
could only be isolated, when a slight excess of 1 was used, which
could easily be separated from 7 by fractional crystallization at
low temperature. The bis(aryloxy) titanocene 13 could be prepared
in a more straightforward way by treatment of 1 with 4-nitrophe-
nol in a 1:2.1 molar ratio and using Et2NH as base (Reaction 2).
After appropriate work-up, organometallic 13 could be isolated
as an orange solid in 84% yield.
SiMe3
SiMe3
Cl
Cl
Cl
Et2NH
Ti
+
HOR
Ti
R
ð1Þ
O
SiMe3
SiMe3
2 - 12
1
SiMe3
SiMe3
NO2
NO2
O
O
Cl
Cl
Et2NH
Ti
2 HO
NO2
Ti
+
ð2Þ
SiMe3
SiMe3
13
1
After appropriate work-up, titanocene chlorides 2–12 could be
isolated as orange (4, 10–12), red (2, 3, 5–8) or purple (9) solids
in very good to excellent yield (Table 1). They dissolve in polar or-
ganic solvents including diethyl ether, tetrahydrofuran and dichlo-
romethane. These compounds are fairly stable to air and oxygen
but sensitive toward acids.
The Et2NH/diethyl ether reaction media could also successfully
be applied for the synthesis of homodinuclear titanium compounds
as outlined in Reaction 3. In the thus formed compounds
([Ti]Cl)2(l-OC6H4O) (14) and ([Ti](Cl)(l-OC6H4-4))2 (15) two [Ti]Cl
units are connected by a OC6H4O or a OC6H4C6H4O bridging moi-
ety. These molecules could be isolated in excellent yield as dark
purple (14) or red (15) solid materials (Section 4).
SiMe3
SiMe3
Me3Si
Cl
Cl
O
Cl
Ti
Et2NH
HO
OH
Ti
2
Ti
+
Cl
O
ð3Þ
n
n
SiMe3
SiMe3 Me3Si
14: n = 1
15: n = 2
1

S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 3213–3222
3215
Fig. 1. Resonance signals of the cyclopentadienyl ring protons in the 1H NMR spectrum of 6 (CDCl3, 250.12 MHz, rel. SiMe4: d = 0.00 ppm, CDCl3 solvent reference signal:
d = 7.26 ppm, 25 °C).
The 1H NMR spectra of 2–15 show the expected resonance sig-
nals and coupling patterns [8]. Noteworthy is that in the 1H NMR
spectra of 2, 3, 5–12 and 15 the cyclopentadienyl ring protons split
into two pairs of duplets-of-triplets, which differs from the spec-
trum of 1, where two pseudo-triplets are characteristic (6.56 and
6.78 ppm; AA0XX0 spin system, JHH = 1.8 Hz). [16] This can be ex-
plained by a lower symmetry, when going from 1 with a distorted
tetrahedral A2X2 substituent pattern at Ti to an ABCD pattern for 2–
12, 14 and 15. Exemplary, the chemical shift window of the cyclo-
pentadienyl part of the 1H NMR of 6 is depicted in Fig. 1. The res-
and meta-position at the benzene core should allow to carry out
comparative studies of the electronic properties on the titanium
atoms.
In general, titanium(IV) compounds show reversible [Ti(IV)/
Ti(III)] redox couples [19,20]. However, this could only be observed
for organometallics 1–3, while 4–15 possess irreversible reduc-
tions as summarized in Table 2.
The introduction of an alkyloxy substituent in 2–4 results in a
shift of the [Ti(IV)/Ti(III)] potential by about 0.10 V to more posi-
tive values as compared to 1, which can be explained by the some-
what stronger electron-withdrawing properties of the RO groups
(R = Me, CH2PPh2, CH2Fc) (Table 2). Since these potentials occur
at practically the same value (ꢁ1.42, ꢁ1.44 V) it can be concluded
that there is no electronic influence of the alkyloxy groups R onto
the titanium(IV) ion. Additionally, for 3 an irreversible oxidation
wave was found at +0.43 V which most likely can be assigned to
the oxidation of the phosphorus atom. Similar observations were
made for phosphane-functionalized ferrocenes and, for example,
iPr3P. [21] The heterobimetallic molecule 4 shows next to the
reduction potential at ꢁ1.44 V ([Ti(IV)/Ti(III)]) a reversible one-
onances at 6.53 and 6.71 ppm can be assigned to the a-positioned
cyclopentadienyl ring protons with coupling constants of
4
3JHH = 3 Hz and JHH = 1.9 Hz, respectively, while at 6.39 and
6.43 ppm the resonance signals for the b-positioned protons are
found. A similar behavior is observed for the cyclopentadienyl ring
carbon atoms in the 13C{1H} NMR spectra of 2–15 (e.g., C : 127.5
a
and 128.9, Cb: 115.0 and 119.0, ipso-C: 130.3 ppm).
The successful formation of organometallic 2–15 could addi-
tionally be monitored by 13C{1H} NMR spectroscopy. The quater-
nary Ti–O–C carbon atoms, for example, upon formation of 6, is
shifted by ca. 12 ppm to lower field as compared to the starting
material 4-hydroxybenzonitrile and is found at 173.4 ppm.
In the IR spectrum of 10 a mCO absorption band is observed at
1673 cmꢁ1 (for comparison, the mCO of 40-methoxyacetophenone
absorbs at 1668 cmꢁ1) [17]. This is also characteristic for 11
electron [Fe(II)/Fe(III)] oxidation at ꢁ0.03 V (
DE = 0.17 V) which
can be assigned to the ferrocene unit [22]. This potential is thereby
not shifted, when compared to hydroxylmethylferrocene, which is
in accordance with the [Ti(IV)/Ti(III)] couple [23].
(1712 cmꢁ1
1714 cmꢁ1). The cyano group in 6 shows its mC„N frequency at
2220 cmꢁ1 (e.g., para-methoxybenzonitrile C„N = 2219 cmꢁ1
;
for comparison, methyl anisate absorbs at
Table 2
Electrochemical data of 1–15a
m
)
Compound. Ered(Ti)
E
,
(V) (D
Ep Ered (V)
Eox
E
,
(V) (DEp
½ red
½ ox
[17]. The nitro group present in 7, 12 and 13 consists of two identi-
cal N–O bonds for which symmetrically and asymmetrically vibra-
tions are characteristic, for example, the asymmetric band is found
as strong absorption between 1500 and 1530 cmꢁ1 for nitroben-
zene [18]. In 12, where the NO2 functionality is meta-positioned,
the asymmetric mNO vibration was observed at 1526 cmꢁ1. How-
ever, for 7 and 13, which feature para-nitrobenzene units, the
(V)
(V))
(V)
(mV))
1
2
3
4
5
6
7
8
ꢁ1.50b
ꢁ1.42b
ꢁ1.44b
ꢁ1.44
ꢁ1.80
ꢁ1.61
ꢁ1.65
ꢁ1.80
ꢁ1.86
ꢁ1.57
ꢁ1.60
ꢁ1.81
ꢁ1.64
ꢁ1.37
ꢁ1.49
ꢁ1.45 (0.10)
ꢁ1.33 (0.18)
ꢁ1.34 (0.20)
ꢁ2.02, ꢁ2.60
ꢁ2.53, ꢁ3.07 +0.43
ꢁ 2.03
ꢁ0.03 (0.17)
ꢁ2.38, ꢁ2.81
ꢁ2.06
ꢁ2.24, ꢁ2.74
ꢁ2.40
appropriate mNO is shifted to higher wavenumbers (7: 1582 cmꢁ1
,
13: 1581 and 1587 cmꢁ1) explainable by benzenes substituted with
9
ꢁ2.44
+0.53 (0.26)
10
11
12
13
14
15
ꢁ1.90, ꢁ2.12
ꢁ2.64
strong electron-withdrawing groups [18b]. The occurrence of two
asymmetric mNO bands for 13 is in accordance with its structure in
the solid state. Other characteristic vibrations for 2–15 are observed
in the expected ranges (Section 4) [18b].
ꢁ1.99, ꢁ2.22
ꢁ2.69
ꢁ1.87, ꢁ2.92 +0.76
+0.28 (0.20)
+0.50 (0.29)
ꢁ2.17
2.2. Cyclic voltammetry
a
10ꢁ3 M solutions in tetrahydrofuran at 25 °C, [n-Bu4N]PF6 supporting electro-
lyte (0.1 M), argon, scan rate = 0.2 V sꢁ1. All potentials are referenced to the FcH/
FcH+ redox couple (Fc = ( 5-C5H5)2Fe) with E = 0.00 V. Ered(Ti) = wave maxima of
the 1st titanium reduction. E
to-peak separation Ep. Ered = wave maxima of the 2nd and 3rd irreversible tita-
nium reduction. Eox = wave maxima of the irreversible oxidation. E½ ox = potential
of the anodic redox couple with peak-to-peak separation Ep.
g
To study the effect of electron-withdrawing and electron-
donating substituents at the benzene groups as well as the conse-
quence of continuous and discontinuous
of prepared alkyloxy- and aryloxy-titanocenes 2–15 (vide supra)
were subjected to cyclic voltammetric measurements in tetrahy-
drofuran at 25 °C. The introduction of diverse substituents in para
½
½,red = potential of the [Ti(IV)/Ti(III)] couple with peak-
D
p-conjugation the series
,
D
b
Although the [Ti(IV)/Ti(III)] redox couple is reversible, for comparative reasons
the potential of the reduction wave is additionally listed.

3216
S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 3213–3222
Fig. 2. Correlation between the [Ti(IV)/Ti(III)] reduction potentials and the
r
Hammett substituent constants.
For the aryloxy-substituted titanocenes 5–15 the [Ti(IV)/Ti(III)]
reductions vary in a 500 mV window (Table 2). To study the influ-
ence of the substituents of 5–13 vs. the 1st titanium-centered
reduction, these values were plotted against the rp/m Hammett
substituent constants reported by Taft (Fig. 2) [24].
As it can be seen from Fig. 2 the [Ti(IV)/Ti(III)] reductions of 5–
13 show a modest correlation with the rp/m Hammett constants. A
Fig. 3. Displacement ellipsoid plot (50% probability level) of the molecular
structure of 4 with the atom numbering scheme (the hydrogen atoms are omitted
for clarity). Selected bond distances (Å), angles (°), and torsion angels (°): Ti1–Cl1,
2.395(3); Ti1–O1, 1.849(4); O1–C17, 1.415(5); D1–Ti1, 2.070(4); D2–Ti1, 2.064(3);
D3–Fe1, 1.637(3); Ti1–O1–C17, 132.5(3); Cl1–Ti1–O1, 90.9(1); D1–Ti1–D2,
129.7(1); D3–Fe1–D4, 178.4(2); Ti1–O1–C17–C18, 146.6(3). D1, D2: centroids of
the titanocene cyclopentadienyl ligands (D1 = C1
– C5, D2 = C9–C13). D3, D4:
similar dependence of the reduction potentials was reported by
centroids of the ferrocene cyclopentadienyl ligands (D3 = C18–C22, D4 = C23–C27).
Langmaier et al. for methyl-substituted titanocene dichlorides of
type (g
5-C5H5ꢁnMen)2TiCl2 (n = 0–5) showing an average shift of
the 1st reduction per one methyl group of 0.095 V [25]. It must
be noted that the titanium-centered reductions of 5–15 originate
from irreversible reductions which cannot be measured and com-
pared as accurately as fully reversible electrochemical processes.
With this uncertainty in mind we propose a direct dependence of
the nature of the aryl-substituent on the [Ti(IV)/Ti(III)] reduction
via the phenolic oxygen atom. Hence, the electronic configuration
of the titanium ion can be predicted by selecting appropriately
substituted phenols.
In addition to the titanium-centered reduction for 9, 14 and 15
(vide supra) a oxidation wave was observed at 0.53 V (
DE = 0.26 V)
for 9, 0.28 V ( E = 0.20 V) for 14, and 0.50 V ( E = 0.29 V) for 15
D
D
which can be assigned to an oxidation of the hydroquinone (9,
14) and 1,10-dihydroxybiphenyl (15) moieties [26,27]. Remarkably,
these compounds can be easier oxidized than related 1,4-dime-
thoxybenzene and 1,10-dimethoxybiphenyl [26]. In the series of
([Ti]Cl)n(l-OC6H4O-1,4)Me2ꢁn (n = 0–2), 1,4-dimethoxybenzene
(n = 0) shows a reversible oxidation at +0.90 V (
D
E = 0.07 V) [26,
28]. Exchange of one methyl group by a [Ti]Cl unit (9, n = 1) shifts
the oxidation potential by 0.37 V to more negative values. A second
replacement (14, n = 2) leads to a further shift of 0.25 V. The mag-
Fig. 4. Displacement ellipsoid plot (50% probability level) of the molecular
structure of 5 with the atom numbering scheme (the hydrogen atoms are omitted
for clarity). Selected bond distances (Å), angles (°), and torsion angels (°): Ti1–Cl1,
2.3964(6); Ti1–O1, 1.896(1); O1–C17, 1.355(2); D1–Ti1, 2.082(1); D2–Ti1, 2.085(1);
Ti1–O1–C17, 137.5(1); Cl1–Ti1–O1, 93.06(4); D1–Ti1–D2, 130.3(1); Ti1–O1–C17–
C18, ꢁ49.9(3). D1, D2: centroids of the titanocene cyclopentadienyl ligands
(D1 = C1–C5, D2 = C9–C13).
nitude of the shift is very notable since, for example, in (g5
-
C5H5)2Ti(CH2SiMe3)(C„CFc) the ferrocene oxidation is only facili-
tated by 0.080 V as compared to HC„CFc [29]. Therefore, it can
be concluded that in 9, 14 and 15 an effective resonance stabiliza-
tion of the oxidized species (radical cation) takes place.
The 2nd irreversible oxidation wave found for 14 at 0.76 V can
be assigned to the further oxidation of the hydroquinone radical to
a dication as reported by Parker et al. for 1,4-dimethoxybenzene
[26a]. However, this 2nd oxidation was not observed for 9 and
15, most probably due to the electrochemical window of tetrahy-
drofuran used as solvent during the studies.
given in the legends of these figures, the respective crystal and
intensity collection data are summarized in Table 3 (Section 4).
Molecules 4, 5, 9, and 11–13 show a distorted tetrahedral coor-
dination geometry at titanium set-up by two C5H4SiMe3 groups, a
chloride and an oxygen atom (4, 5, 9, 11 and 12) or two oxygen
atoms (13). As characteristic for other titanocene complexes the
Ti1–D1 and Ti1–D2 separations (D1, D2 = centroids of the cyclo-
pentadienyl ligands) are found between 2.064(3) (D2–Ti1 in 4)
and 2.093(1) Å (D1–Ti1 in 12), and the D1–Ti1–D2 angles are rang-
ing from 129.7(1)° (4) to 131.2(1)° (12) [30]. The relative positions
of the SiMe3 groups toward each other differ to a great extent. An
2.3. Structures of 4, 5, 9, and 11–13 in the solid state
Single crystals of 4, 5, 9, and 11–13 suitable for X-ray structure
analysis were obtained by slow evaporation of diethyl ether solu-
tions containing the corresponding compounds at ꢁ30 °C. The
molecular structures are shown in Figs. 3–8. Geometric details are

S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 3213–3222
3217
Fig. 7. Displacement ellipsoid plot (30% probability level) of the molecular
structure of 12 with the atom numbering scheme. The nitro group is disordered
and has been refined to split occupancies of 0.42/0.58 (the hydrogen atoms and one
disordered nitro group are omitted for clarity). Selected bond distances (Å), angles
(°), and torsion angels (°): Ti1–Cl1, 2.3780(8); Ti1–O1, 1.895(2); O1–C17, 1.336(3);
N1–C19, 1.473(4); D1–Ti1, 2.093(1); D2–Ti1, 2.077(1); Ti1–O1–C17, 145.9(2); Cl1–
Ti1–O1, 95.2(6); D1–Ti1–D2, 131.2(1); Ti1–O1–C17–C18, 56.4(4); C18–C19–N1–
O2, 20.7(2); C18–C19–N1–O20, ꢁ19.2(2). D1, D2: centroids of the titanocene
cyclopentadienyl ligands (D1 = C1–C5, D2 = C9–C13).
Fig. 5. Displacement ellipsoid plot (50% probability level) of the molecular
structure of 9 with the atom numbering scheme (the hydrogen atoms are omitted
for clarity). Selected bond distances (Å), angles (°), and torsion angels (°): Ti1–Cl1,
2.3854(8); Ti1–O1, 1.880(2); O1–C1, 1.346(3); O2–C4, 1.376(3); D1–Ti1, 2.092(1);
D2–Ti1, 2.091(1); Ti1–O1–C1, 147.4(2); Cl1–Ti1–O1, 98.9(5); D1–Ti1–D2, 130.2(1);
Ti1–O1–C1–C2, 3.7(4); C3–C4–O2–C7, 1.6(4). D1, D2: centroids of the titanocene
cyclopentadienyl ligands (D1 = C8–C12, D2 = C16–C20).
Fig. 8. Displacement ellipsoid plot (50% probability level) of the molecular
structure of 13 with the atom numbering scheme (the hydrogen atoms are omitted
for clarity). Selected bond distances (Å), angles (°), and torsion angels (°): Ti1–O1,
1.913(2); Ti1–O2, 1.918(2); O1–C17, 1.324(3); O4–C23, 1.327(3); N1–C20, 1.451(3);
N2–C26, 1.459(4); D1–Ti1, 2.087(2); D2–Ti1, 2.085(2); Ti1–O1–C17, 150.3(2); Ti1–
O4–C23, 140.4(2); O1–Ti1–O4, 95.5(1); D1–Ti1–D2, 130.9(1); Ti1–O1–C17–C18,
9.3(5); Ti1–O4–C23–C24, 42.4(4); C19–C20–N1–O3, 160.7(3); C25–C26–N2–O5,
173.2(3). D1, D2: centroids of the titanocene cyclopentadienyl ligands (D1 = C1–C5,
D2 = C9–C13).
Fig. 6. Displacement ellipsoid plot (50% probability level) of the molecular
structure of 11 with the atom numbering scheme (the hydrogen atoms are omitted
for clarity). Selected bond distances (Å), angles (°), and torsion angels (°): Ti1–Cl1,
2.3683(9); Ti1–O1, 1.909(2); O1–C1, 1.326(2); D1–Ti1, 2.063(1); D2–Ti1, 2.085(1);
Ti1–O1–C1, 143.3(1); Cl1–Ti1–O1, 94.10(5); D1–Ti1–D2, 130.3(1); Ti1–O1–C1–C2,
37.1(3); C3–C4–C7–O3, 168.0(2); C4–C7–O3–C8, ꢁ178.5(2). D1, D2: centroids of
the titanocene cyclopentadienyl ligands (D1 = C9–C13, D2 = C17–C21).
almost eclipsed conformation is found in 9, while for 4, 5 and 11
completely staggered and for 12 and 13 partially staggered confor-
mations are typical.
The O1–Ti1–O4 bite angle in 13 is 95.5(1)°, while the O–Ti–Cl
one in 4, 5, 9, 11 and 12 is found between 90.9(1)° (4) and
98.9(5)° (9). This shows that there is no significant steric
effect on the titanium atom resulting from the substituents RO
vs. Cl.
The Ti–O distances are located between 1.880(2) Å for 9 and
1.918(2) Å for 13. Compared with previously reported dTi–O values
of 1.855(2) Å for (
g
5-C5H5)2Ti(OEt)(Cl) [30a], 1.835(2) Å for (g5
-
-
C5H5)2Ti(OMe)(C„N) [30b], or 1.860(5) Å for (g l
5-C5H5)Ti(
OC6H3-2-PPh2-6-tBu)Cl2 [32b] the Ti–O bonds appear to be slightly
elongated, which is consistent with the presence of a somewhat
lower Ti O
p-donation and a decreased bond order in 4, 5, 9,
and 11–13 [31,32].

3218
S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 3213–3222
Table 3
Crystal and intensity collection data for 4, 5, 9, and 11–13
4
5
9
11
12
13
Empirical formula
Chemical formula
Formula weight
Crystal system
Space group
a (Å)
C
C
27H37ClFeOSi2Ti
27H37ClFeOSi2Ti
C22H31ClOSi2Ti
C22H31ClOSi2Ti
451
Orthorhombic
Pna21
14.173(2)
18.183(3)
9.1832(15)
2366.7(7)
90
C23H33ClO2Si2Ti
C23H33ClO2Si2Ti
481.02
Monoclinic
P21/n
7.4986(13)
16.046(3)
20.854(4)
2485.2(8)
97.920(4)
1.286
C24H33ClO3Si2Ti
C24H33ClO3Si2Ti
509.03
Monoclinic
P21/c
7.262(3)
23.759(6)
15.145(4)
2608.1(13)
93.55(2)
1.296
C22H30ClNO3Si2Ti
C22H30ClNO3Si2Ti
496
Monoclinic
C2/c
30.910(3)
7.5901(7)
21.854(2)
5124.5(8)
91.871(2)
1.286
C28H34N2O6Si2Ti
C28H34N2O6Si2Ti
598.65
Monoclinic
P21/n
572.95
Monoclinic
P21/c
7.508(9)
24.22(3)
15.598(19)
2822(6)
95.74(2)
1.348
8.980(7)
b (Å)
15.412(10)
21.849(16)
3011(4)
95.37(6)
1.321
c (Å)
V (Å3)
b (°)
qscalc (g cmꢁ3
)
1.266
F(000)
1200
952
1016
1072
2080
1256
Z
4
4
4
4
8
4
Crystal dimensions (mm)
Radiation (k, Å)
0.96 ꢂ 0.16 ꢂ 0.04
0.9 ꢂ 0.4 ꢂ 0.2
0.50 ꢂ 0.40 ꢂ 0.04
0.9 ꢂ 0.2 ꢂ 0.2
0.3 ꢂ 0.1 ꢂ 0.1
0.30 ꢂ 0.30 ꢂ 0.06
Mo K
a
(0.71073)
Mo K
a
(0.71073)
Mo K
a
(0.71073)
Mo K
a
(0.71073)
Mo K
a
(0.71073)
Mo Ka (0.71073)
Absorption correction
Maximum, minimum transmission
Absorption coefficient (
Temperature (K)
Scan range (°)
Empirical
0.9613, 0.4487
0.994
Empirical
0.99999, 0.92560
0.585
Empirical
0.9778, 0.7655
0.565
Empirical
0.8989, 0.6399
0.545
Empirical
0.99999, 0.58251
0.554
Empirical
0.99999, 0.957143
0.406
l )
, mmꢁ1
173
293
293
173
298
223
1.56 6 h6 26.00
ꢁ2 6 h 6 9
ꢁ17 6 k 6 29
ꢁ19 6 l 6 19
10618
1.82 6 h6 25.99
ꢁ17 6 h 6 17
ꢁ22 6 k 6 22
ꢁ11 6 l 6 11
24064
1.61 6 h 6 26.00
ꢁ9 6 h 6 8
ꢁ13 6 k 6 19
ꢁ25 6 l 6 25
14549
1.71 6 h 6 25.99
ꢁ2 6 h 6 8
ꢁ29 6 k 6 29
ꢁ14 6 l 6 18
9848
1.86 6 h 6 26.41
ꢁ38 6 h 6 38
0 6 k 6 9
0 6 l 6 27
22399
1.62 6 h 6 26.00
ꢁ11 6 h 6 11
ꢁ19 6 k 6 19
ꢁ26 6 l 6 26
31186
Index ranges
Total reflections
Unique reflections
5527
4661
4880
4241
5252
5889
Observed reflections [I P 2
Refined parameters
Restraints
r(I)]
2380
304
0
4446
244
1
3375
262
0
3431
280
0
3428
296
13
3714
352
0
Completeness to hmax (%)
99.70
99.90
99.90
82.70
99.70
99.90
R1, wR2 [I P 2
r
(I)]a
0.0577, 0.0683b
0.1859, 0.0838b
0.1200, 0.807
0.0238, 0.0603c
0.0258, 0.0611c
0.0322, 1.027
0.0395, 0.0811d
0.0733, 0.0887d
0.0521, 0.976
0.0333, 0.0874e
0.0454, 0.0914e
0.0299, 1.050
0.0438, 0.0955f
0.0810, 0.1083f
0.0546, 1.015
0.0453, 0.0970g
0.0923, 0.1084g
0.0835, 0.964
R1, wR2 (all data)a
Rint, S
Maximum, minimum peaks in final
0.525, ꢁ0.573
0.202, ꢁ0.189
0.322, ꢁ0.272
0.273, ꢁ0.235
0.236, ꢁ0.212
0.282, ꢁ0.259
Fourier map (e Åꢁ3
)
a
w = 1/[r
2(F2o) + (xP)2 + yP] where P = [Fo2 + 2F2c]/3.
x = 0.012, y = 0.
x = 0.0365, y = 0.1959.
x = 0.0415, y = 0.
x = 0.053, y = 0.2563.
x = 0.0468, y = 2.4271.
x = 0.0539, y = 0.
b
c
d
e
f
g
The aryloxy-titanocenes 9, and 11–13 possess functional groups
3. Conclusion
such as MeO, MeO2C, and NO2 at the phenoxy entity. For all com-
pounds the electron-donating (9: 4-OMe) or electron-withdrawing
moieties (11: 4-CO2Me, 12: 3-NO2, 13: 4-NO2) are almost coplanar
to the plane spanned by the phenyl ring (for selected torsion angles
see Fig. 4–8), thus assuring optimal electronic overlap between
these units. This can further be confirmed by comparing the
Alkyloxy- and aryloxy-titanocene chlorides of type [Ti](Cl)(OR)
(R = Me, CH2PPh2, CH2Fc, C6H5, C6H4-4-C„N, C6H4-4-NO2, C6H4-
4-Me, C6H4-4-OMe, C6H4-4-C(O)Me, C6H4-4-CO2Me, C6H4-3-NO2;
[Ti] = (g g g
5-C5H4SiMe3)2Ti; Fc = ( 5-C5H4)( 5-C5H5)Fe) were synthe-
sized in high yield by reacting [Ti]Cl2 with the respective alcohols
ROH in a 1:1 molar ratio and in presence of Et2NH. In addition, the
synthesis of diaryloxy-titanocenes (for example, [Ti](OC6H4-4-
NO2)2) is reported by changing the ratio of 1 and ROH to 1:2. This
synthesis methodology also allows the preparation of dinuclear
Caryl–Nnitro bond distances in 12 and 13 (Figs. 7 and 8). The nitro
group in 12 is in meta-position and shows a distance of d(N1–
C19) = 1.473(4) Å, while in 13 the two carbon-nitrogen bonds are
by 0.022 and 0.015 Å, respectively, shorter. This suggests an
increased participation of
a 1,4-benzoquinone-like resonance
complexes of composition ([Ti](Cl))2(l-OC6H4O) and ([Ti](Cl)(l-
structure in 12 and 13, and thus, an electronic interaction between
the [Ti](Cl)- and para-NO2 groups. An electronic interaction be-
tween titanium and the aryl group is further verified by an in-
creased hybridization of the oxygen atom resulting in
significantly larger Ti–O–C angles (Figs. 3–8) in 9, and 11–13
(143.3(1)° to 150.3(2)°) as compared to 4 (132.5(3)°) and a higher
OC6H4-4))2, respectively. Cyclic voltammetric studies showed no
influence of the nature of the alkyloxy substituent on the electronic
properties of the titanium(IV) ion. In contrast, for the phenol-
substituted titanocenes a strong influence was observed and the
[Ti(IV)/Ti(III)] reduction potentials could be correlated with the
rp/m Hammett substituent constants. Aryloxy-titanocenes, featur-
ing a hydroquinone unit as given in [Ti](Cl)(OC6H4-4-OMe) or
bond order of one of the two Caryl–O
r-bonds in 9, whereby the
C1–O1 separation next to titanium is by 0.03 Å shorter than the
C4–O2 one (d(C1–O1) = 1.346(3), d(C4–O2) = 1.376(3) Å).
In contrast to mononuclear 5, 9, and 11–13 in 4 a ferrocenyl
moiety is present as a second organometallic unit. This entity
shows geometric features that resemble to the structural data
characteristic for ferrocenes [33].
([Ti](Cl))2(l-OC6H4O), can be easier oxidized than the related
dimethoxy ether- or 1,4-dimethoxybenzene-functionalized ones,
which suggest an effective resonance stabilization of the oxidized
species.
Cyclic voltammetric, IR and solid state data point to an electron
transfer via the oxygen atom between the aryloxy group and the

S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 3213–3222
3219
Ti(IV) ion. Furthermore, it is possible to predict the electronic
configuration at titanium by selecting appropriately substituted
phenols.
single portion 0.60 mL of Et2NH. This reaction solution was stirred
for 5 h at 25 °C. Filtration through a pad of Celite and evaporation
of all volatile materials in oil-pump vacuum gave 1.85 g (3.23 mmol,
74% based on 1) of 3 in form of a red-brown solid.
M.p.: [°C] 142 (dec.). 1H NMR (CDCl3): [d] 0.26 (s, 18H, SiMe3),
2
4
3
4. Experimental
5.26 (d, JPH = 7.11 Hz, 2H, CH2), 6.22 (dt, JHH = 1.90 Hz, JHH
=
4
3
3.00 Hz, 2H, C5H4), 6.42 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H,
3
4
4.1. General methods
C5H4), 6.47 (dt, JHH = 3.00 Hz, JHH = 1.90 Hz, 2H, C5H4), 6.54 (dt,
3JHH = 3.00 Hz, JHH = 1.90 Hz, 2H, C5H4), 7.3–7.6 (m, 10H, C6H5).
4
13C{1H} NMR (CDCl3): [d] ꢁ0.1 (SiMe3), 84.8 (CH2), 117.5 (CH/
C5H4), 118.5 (CH/C5H4), 125.2 (CH/C6H5), 125.8 (CH/C5H4), 127.3
All reactions were carried out under an atmosphere of purified
nitrogen using standard Schlenk techniques. Tetrahydrofuran,
diethyl ether, benzene and n-hexane were purified by distillation
from sodium/benzophenone ketyl. MeOH was purified by distilla-
tion from magnesium. Et2NH and Et3N were dried by distillation
from KOH. NMR spectra were recorded with a Bruker Avance 250
spectrometer (1H NMR at 250.12 MHz, 13C{1H} NMR at
62.86 MHz and 31P{1H} NMR at 101.20 MHz) in the Fourier trans-
form mode. Chemical shifts are reported in d units (parts per mil-
lion) downfield from tetramethylsilane (d = 0.0 ppm) with the
solvent as the reference signal (CDCl3: 1H NMR, d = 7.26 ppm;
13C{1H} NMR, d = 77.0 ppm). 31P{1H} NMR spectra were recorded
with P(OMe)3 (d = 139.0 ppm) as external reference rel. to H3PO4
(d = 0.0 ppm). Cyclic voltammograms were recorded in a dried cell
purged with argon at 25 °C. Platinum wires served as working and
as counter electrode. A saturated calomel electrode served as refer-
ence electrode. For ease of comparison, all electrode potentials are
converted using the redox potential of the ferrocene-ferrocenium
(iC/C5H4), 128.2 (CH/C5H4), 128.4 (d, JCP = 14.0 Hz, CH/C6H5),
3
2
i
133.2 (d, JCP = 17.5 Hz, CH/C6H5), 136.9 (d, 1JCP = 14.5 Hz, C/C6H5).
31P{1H} NMR (CDCl3): ꢁ10.6 (PPh2). Anal. Calc. for C29H38ClOPSi2Ti
(573.08): C, 60.78; H, 6.68. Found: C, 60.43; H, 6.40%.
4.2.3. Synthesis of [Ti](Cl)(OCH2Fc) (4)
To a solution of 400 mg (1.02 mmol) of [Ti]Cl2 (1) and 220 mg
(1.02 mmol) of HOCH2Fc in 100 mL of diethyl ether were added
0.15 mL of Et2NH in a single portion. The reaction solution was stir-
red for 6 h at 25 °C and afterward it was worked-up as described
above. Yield: 520 mg (0.91 mmol, 89% based on 1) of 4; orange-
brown solid.
M.p.: [°C] 166 (dec.). 1H NMR (CDCl3): [d] 0.18 (s, 18H, SiMe3),
4.1 (m, 9H, Fc), 5.10 (s, 2H, CH2), 6.30 (pq, JHH = 2.4 Hz, 2H, C5H4),
6.35 (pq, JHH = 2.4 Hz, 2H, C5H4), 6.50 (pt, JHH = 2.4 Hz, 4H, C5H4).
13C{1H} NMR (CDCl3): [d] –0.1 (SiMe3), 68.0 (CH/Fc), 68.3 (CH/
C5H5), 68.4 (iC/Fc), 69.1 (CH/Fc), 80.8 (CH2), 117.0 (CH/C5H4),
117.2 (CH/C5H4), 124.2 (CH/C5H4), 125.7 (CH/C5H4), 127.7 (iC/
C5H4). Anal. Calc. for C27H37ClFeOSi2Ti (572.92): C, 56.60; H, 6.51.
Found: C, 57.04; H, 6.64%.
couple FcH/FcH+ (FcH = ( 5-C5H5)2Fe) as the reference
g
(E0 = 0.00 V) [34]. Electrolyte solutions were prepared from [n-
Bu4N]PF6 (dried in oil-pump vacuum at 120 °C, c = 0.1 M) and
freshly distilled tetrahydrofuran. The respective organometallic
complexes were added at c = 1 mM. Cyclic voltammograms were
recorded at a scan rate of 100 mV sꢁ1 using a Radiometer Copenha-
gen DEA 101 Digital Electrochemical Analyzer with an IMT 102
Electrochemical Interface. Melting points were determined using
sealed nitrogen purged capillaries on a Gallenkamp melting point
apparatus. Microanalyses were performed by the Department of
Organic Chemistry at Chemnitz, Technical University.
4.2.4. Synthesis of [Ti](Cl)(OPh) (5)
The synthesis and work-up procedures are identical with the
one described for the preparation of 2 (500 mg (1.27 mmol) of
[Ti]Cl2 (1), 120 mg (1.28 mmol) of phenol, 150 mL of diethyl ether,
and 0.3 mL of Et2NH). Yield: 500 mg (1.11 mmol, 87% based on 1);
red solid.
M.p.: [°C] 111. 1H NMR (CDCl3): [d] 0.24 (s, 18H, SiMe3), 6.33 (dt,
3
4
4JHH = 1.9 Hz, JHH = 3.0 Hz, 2H, C5H4), 6.43 (dt, JHH = 1.9 Hz,
4.2. General remarks
3JHH = 3.0 Hz, 2H, C5H4), 6.56 (dt, JHH = 3.0 Hz, JHH = 1.9 Hz, 2H,
C5H4), 6.65 (ddd, JHH = 9.0 Hz, JHH = 1.4 Hz, JHH = 1.1 Hz, 2H,
3
4
3
4
4
[Ti]Cl2 (1) [35], HOCH2PPh2 [36] and HOCH2Fc [37] were pre-
pared following published procedures. All other chemicals were
purchased from commercial sources and were used without any
further purification.
3
4
C6H5), 6.69 (dt, JHH = 3.0 Hz, JHH = 1.9 Hz, 2H, C5H4), 6.83 (tt,
4
3
3JHH = 7.3 Hz, JHH = 1.1 Hz, 1H, C6H5), 7.22 (ddd, JHH = 9.0 Hz,
4
3JHH = 7.3 Hz, JHH = 3.2 Hz, 2H, C6H5). 13C{1H} NMR (CDCl3): [d]
ꢁ0.2 (SiMe3), 114.4 (CH/C5H4), 116.8 (o-CH/C6H5), 118.2 (CH/
C5H4), 119.9 (p-CH/C6H5), 126.5 (CH/C5H4), 128.8 (iC/C5H4), 128.9
(CH/C5H4), 129.0 (m-CH/C6H5), 170.9 (C–OTi). Anal. Calc. for
4.2.1. Synthesis of [Ti](Cl)(OMe) (2)
Five hundred milligrams (1.27 mmol) of [Ti]Cl2 (1) and 41 mg
(1.28 mmol) of methanol were dissolved in 150 mL of diethyl ether
and 0.20 mL of Et2NH were added in a single portion. The reaction
solution was stirred for 4 h at 25 °C. Filtration through a pad of Cel-
ite and evaporation of the eluate under reduced pressure gave
470 mg (1.21 mmol, 95% based on 1) of the title compound as a
red solid.
C22H31ClOSi2Ti (450.97): C, 58.59; H, 6.93. Found: C, 58.87; H,
6.85%.
4.2.5. Synthesis of [Ti](Cl)(OC6H4-4-C„N) (6)
The synthesis and work-up procedures are identical with the
one described for the preparation of 3 (787 mg (2.00 mmol) of
[Ti]Cl2 (1), 238 mg (2.00 mmol) of HOC6H4-4-C„N, 200 mL of
diethyl ether, and 0.3 mL of Et2NH). Yield: 915 mg (1.92 mmol,
96% based on 1); orange solid.
M.p.: [°C] 156 (dec.). 1H NMR (CDCl3): [d] 0.21 (s, 18H, SiMe3),
4
3
4.17 (s, OCH3), 6.34 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4),
4
3
6.37 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4), 6.47 (dt,
3JHH = 3.00 Hz, JHH = 1.90 Hz, 2H, C5H4), 6.58 (dt, JHH = 3.00 Hz,
4JHH = 1.90 Hz, 2H, C5H4). 13C{1H} NMR (CDCl3): [d] ꢁ0.3 (SiMe3),
70.4 (OCH3), 116.8 (CH/C5H4), 117.1 (CH/C5H4), 123.1 (CH/C5H4),
126.1 (CH/C5H4), 128.8 (iC/C5H4). Anal. Calc. for C17H29ClOSi2Ti
(388.90): C, 52.50; H, 7.52. Found: C, 52.20; H, 7.24%.
4
3
M.p.: [°C] 123. IR (KBr): [cmꢁ1] 2220 (s) [
[d] 0.21 (s, 18H, SiMe3), 6.39 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H,
m
C„N]. 1H NMR (CDCl3):
4
3
4
3
C5H4), 6.43 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4), 6.53 (dt,
3JHH = 3.00 Hz, JHH = 1.90 Hz, 2H, C5H4), 6.67 (dd, JHH = 6.79 Hz,
4
3
4JHH = 2.05 Hz, 2H, C6H4), 6.71 (dt, JHH = 3.00 Hz, JHH = 1.90 Hz,
3
4
3
4
2H, C5H4), 7.50 (dd, JHH = 6.79 Hz, JHH = 2.05 Hz, 2H, C6H4).
13C{1H} NMR (CDCl3): [d] ꢁ0.5 (SiMe3), 101.1 (C–C„N), 115.0
(CH/C5H4), 117.9 (CH/C6H5), 119.0 (CH/C5H4), 119.9 (C„N), 127.0
(CH/C5H4), 128.9 (CH/C5H4), 130.3 (iC/C5H4), 133.5 (CH/C6H5),
4.2.2. Synthesis of [Ti](Cl)(OCH2PPh2) (3)
To 1.71 g (4.35 mmol) of [Ti]Cl2 (1) and 940 mg (4.35 mmol) of
HOCH2PPh2 dissolved in 300 mL of diethyl ether were added in a

3220
S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 3213–3222
173.4 (C–OTi). Anal. Calc. for C23H30ClNOSi2Ti (476.01): C, 58.04; H,
6.35; N, 2,94. Found: C, 58.07; H, 6.79; N, 3.34%.
M.p.: [°C] 117. IR (KBr): [cmꢁ1] 1673 (s) [ C@O]. 1H NMR (CDCl3):
m
[d] 0.21 (s, 18H, SiMe3), 2.55 (s, C(@O)CH3), 6.37 (dt, 4JHH = 1.90 Hz,
3JHH = 3.00 Hz, 2H, C5H4), 6.44 (dt, 4JHH = 1.90 Hz, 3JHH = 3.00 Hz, 2H,
3
4
4.2.6. Synthesis of [Ti](Cl)(OC6H4-4-NO2) (7)
C5H4), 6.55 (dt, JHH = 3.00 Hz, JHH = 1.90 Hz, 2H, C5H4), 6.64 (dd,
4
3
The synthesis is identical with the one described for the prepa-
ration of 3 (393 mg (1.00 mmol) of [Ti]Cl2 (1), 139 mg (1.00 mmol)
of HOC6H4-4-NO2, 100 mL of diethyl ether, and 0.15 mL of Et2NH).
Traces of 1 can be removed by fractional crystallization from a
solution of 1 and 7 in 20 mL of diethyl ether at -30 °C. Yield:
415 mg (0.84 mmol, 84% based on (1); red-brown solid.
3JHH = 8.7 Hz, JHH = 2.0 Hz, 2H, C6H4), 6.70 (dt, JHH = 3.00 Hz,
4JHH = 1.90 Hz, 2H, C5H4), 7.78 (dd, JHH = 8.7 Hz, JHH = 2.0 Hz, 2H,
C6H4). 13C{1H} NMR (CDCl3): [d] ꢁ0.3 (SiMe3), 26.2 (C(@O)CH3),
114.7 (CH/C5H4), 116.9 (CH/C6H4), 118.8 (CH/C5H4), 127.1 (CH/
C5H4), 128.8 (iC/C6H4), 129.2 (CH/C5H4), 130.0 (iC/C5H4), 130.5
(CH/C6H4), 174.7 (C–OTi), 197.0 (C@O). 29Si{1H} NMR (CDCl3): [d]
ꢁ5.53 (C5H4SiMe3). Anal. Calc. for C24H33ClO2Si2Ti (493.01): C,
58.47; H, 6.75. Found: C, 58.07; H, 6.98%.
3
4
M.p.: [°C] 131 (dec.). IR (KBr): [cmꢁ1] 1336 [mN–O
, sym], 1489 (m)
[
mC–C
,
str], 1582 (s) [mN–O
,
asym]. 1H NMR (CDCl3): [d] 0.21 (s, 18H,
4
3
SiMe3), 6.42 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4), 6.46 (dt,
4JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4), 6.55 (dt, JHH = 3.00 Hz,
4.2.10. Synthesis of [Ti](Cl)(OC6H4-4-CO2Me) (11)
3
3
4JHH = 1.90 Hz, 2H, C5H4), 6.66 (dd, JHH = 9.2 Hz, JHH = 2.2 Hz, 2H,
The synthesis and work-up procedures are identical with the
one described for the preparation of 2 (393 mg (1.00 mmol) of
[Ti]Cl2 (1), 152 mg (1.00 mmol) of HOC6H4-4-CO2CH3, and 100 mL
of diethyl ether, 0.15 mL Et2NH). Yield: 500 mg (0.98 mmol, 98%
based on 1); orange solid.
3
4
3
4
C6H4), 6.73 (dt, JHH = 3.00 Hz, JHH = 1.90 Hz, 2H, C5H4), 8.13 (dd,
3JHH = 9.2 Hz, JHH = 2.2 Hz, 2H, C6H4). 13C{1H} NMR (CDCl3): [d]
4
ꢁ0.3 (SiMe3), 115.1 (CH/C5H4), 117.2 (CH/C6H4), 119.2 (CH/C5H4),
125.9 (CH/C6H4), 127.4 (CH/C5H4), 129.2 (CH/C5H4), 130.8
(iC/C5H4), 139.9 (iC/C6H4), 175.6 (C–OTi). Anal. Calc. for C22H30
-
M.p.: [°C] 119. IR (KBr): [cmꢁ1] 1712 (s) [ C@O]. 1H NMR (CDCl3):
m
ClNO3Si2Ti (495.97): C, 53.28; H, 6.10; N, 2.82. Found: C, 52.90;
H, 6.18; N, 2.82%.
[d] 0.21 (s, 18H, SiMe3), 4.16 (s, 3H, OCH3), 6.36 (dt, 4JHH = 1.90 Hz,
3JHH = 3.00 Hz, 2H, C5H4), 6.44 (dt, 4JHH = 1.90 Hz, 3JHH = 3.00 Hz, 2H,
3
4
C5H4), 6.54 (dt, JHH = 3.00 Hz, JHH = 1.90 Hz, 2H, C5H4), 6.63 (dd,
4
3
3JHH = 6.79 Hz, JHH = 2.05 Hz, 2H, C6H4), 6.70 (dt, JHH = 3.00 Hz,
4.2.7. Synthesis of [Ti](Cl)(OC6H4-4-Me) (8)
4JHH = 1.90 Hz, 2H, C5H4), 7.98 (dd, JHH = 6.79 Hz, JHH = 2.05 Hz,
2H, C6H4). 13C{1H} NMR (CDCl3): [d] ꢁ0.2 (SiMe3), 51.7 (OCH3),
114.7 (CH/C5H4), 121.0 (iC/C6H4), 116.8 (CH/C6H4), 118.7 (CH/
C5H4), 127.0 (CH/C5H4), 129.2 (CH/C5H4), 129.9 (iC/C5H4), 131.4
(CH/C6H4), 167.3 (C@O), 174.4 (C–OTi). 29Si{1H} NMR (CDCl3): [d]
ꢁ5.48 (C5H4SiMe3). Anal. Calc. for C24H33ClO3Si2Ti (509.11): C,
56.63; H, 6.54. Found: C, 56.39; H, 6.52%.
3
4
The synthesis and work-up procedures are identical with the
one described for the preparation of 2 (393 mg (1.00 mmol) of
[Ti]Cl2 (1), 108 mg (1.00 mmol) of HOC6H4-4-CH3, 100 mL of
diethyl ether, and 0.15 mL of Et2NH). Yield: 445 mg (0.95 mmol,
95% based on 1); red solid.
M.p.: [°C] 142. 1H NMR (CDCl3): [d] 0.24 (s, 18H, SiMe3), 2.29 (s,
4
3
3H, C6H4CH3), 6.32 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4),
4
3
6.42 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4), 6.55 (m, 4H,
3
4
4.2.11. Synthesis of [Ti](Cl)(OC6H4-3-NO2) (12)
C5H4, C6H4), 6.69 (dt, JHH = 3.00 Hz, JHH = 1.90 Hz, 2H, C5H4),
7.02 (d, JHH = 8.2 Hz, 2H, C6H4). 13C{1H} NMR (CDCl3): [d] ꢁ0.2
3
The synthesis and work-up procedures are identical with the
one described for the preparation of 3 (393 mg (1.00 mmol) of
[Ti]Cl2 (1), 139 mg (1.00 mmol) of HOC6H4-3-NO2, 100 mL of
diethyl ether, and 0.15 mL of Et2NH). Yield: Yield: 450 mg
(0.91 mmol, 91% based on 1); orange solid.
(SiMe3), 20.6 (C6H4CH3), 114.3 (CH/C5H4), 116.4 (CH/C6H4), 118.4
(CH/C5H4), 126.2 (CH/C5H4), 129.1 (CH/C5H4), 129.4 (CH/C6H4),
128.4 (iC/C5H4), 128.8 (iC/C6H4), 169.1 (C–OTi). Anal. Calc. for
C23H33ClOSi2Ti (465.00): C, 59.41; H, 7.15. Found: C, 59.20; H,
M.p.: [°C] 96 (dec.). IR (KBr): [cmꢁ1] 1350 [mN–O
, sym], 1473 (m)
6.90%.
[
mC–C
,
str], 1526 (s) [mN–O
,
asym]. 1H NMR (CDCl3): [d] 0.22 (s, 18H,
4
3
SiMe3), 6.40 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4), 6.44 (dt,
4.2.8. Synthesis of [Ti](Cl)(OC6H4-4-OMe) (9)
4JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4), 6.55 (dt, JHH = 3.00 Hz,
3
3
The synthesis and work-up procedures are identical with the
one described for the preparation of 2 (200 mg (0.51 mmol) of
[Ti]Cl2 (1), 63 mg (0.51 mmol) of HOC6H4-4-OMe, 50 mL of diethyl
ether, and 0.10 mL of Et2NH). Yield: 230 mg (0.48 mmol, 94% based
on 1); purple solid.
4JHH = 1.90 Hz, 2H, C5H4), 6.72 (dt, JHH = 3.00 Hz, JHH = 1.90 Hz,
3
4
3
4
4
2H, C5H4), 7.05 (ddd, JHH = 8.1 Hz, JHH = 2.3 Hz, JHH = 1.0 Hz, 1H,
C6H4-4), 7.34 (t, JHH = 8.1 Hz, 1H, C6H4-5), 7.37 (t, JHH = 2.3 Hz,
3
4
3
4
4
1H, C6H4-2), 7.67 (ddd, JHH = 8.1 Hz, JHH = 2.3 Hz, JHH = 1.0 Hz,
1H, C6H4-6). 13C{1H} NMR (CDCl3): [d] ꢁ0.3 (SiMe3), 111.5 (C2H/
C6H4), 114.0 (C6H/C6H4), 115.0 (CH/C5H4), 119.1 (CH/C5H4), 123.8
(C4H/C6H4), 127.2 (CH/C5H4), 128.9 (CH/C5H4), 129.4 (iC/C5H4),
130.4 (C5H/C6H4), 149.0 (iC3H/C6H4), 170.2 (C–OTi). 29Si{1H} NMR
(CDCl3): [d] ꢁ5.37 (C5H4SiMe3). Anal. Calc. for C22H30ClNO3Si2Ti
(495.97): C, 53.28; H, 6.10; N, 2.82. Found: C, 52.96; H, 6.23; N,
2.90%.
M.p.: [°C] 146. 1H NMR (CDCl3): [d] 0.22 (s, 18H, SiMe3), 3.81 (s,
4
3
3H, OCH3), 6.31 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4), 6.39
4
3
3
(dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 2H, C5H4), 6.52 (dt, JHH
=
4
3
3.00 Hz, JHH = 1.90 Hz, 2H, C5H4), 6.61 (dd, JHH = 9.3 Hz,
4JHH = 3.0 Hz, 2H, C6H4), 6.67 (dt, JHH = 3.00 Hz, JHH = 1.90 Hz,
3
4
3
4
2H, C5H4), 6.77 (dd, JHH = 9.3 Hz, JHH = 3.0 Hz, 2H, C6H4). 13C{1H}
NMR (CDCl3): [d] ꢁ0.2 (SiMe3), 55.6 (OCH3), 113.9 (CH/C6H4),
114.5 (CH/C5H4), 117.1 (CH/C6H4), 118.4 (CH/C5H4), 125.9
(CH/C5H4), 128.3 (iC/C5H4), 129.1 (CH/C5H4), 153.0 (iC/C6H4),
165.9 (C–OTi). 29Si{1H} NMR (CDCl3): [d] ꢁ5.74 (C5H4SiMe3). Anal.
Calc. for C23H33ClO2Si2Ti (467.01): C, 57.43; H, 6.92. Found: C,
57.54; H, 6.94%.
4.2.12. Synthesis of [Ti](OC6H4-4-NO2)2 (13)
The synthesis and work-up procedures are identical with the
one described for the preparation of 3 (393 mg (1.00 mmol) of
[Ti]Cl2 (1), 290 mg (2.1 mmol) of HOC6H4-4-NO2, 100 mL of diethyl
ether, and 0.30 mL of Et2NH). Yield: 415 mg (0.84 mmol, 84% based
on 1); orange solid.
4.2.9. Synthesis of [Ti](Cl)(OC6H4-4-C(O)Me) (10)
M.p.: [°C] 134 (dec.). IR (KBr): [cmꢁ1] 1341 [mN–O
str], 1491 (m) [mC–C str], 1581 (s) [mN–O
asym]. 1H NMR (CDCl3): [d] 0.15 (s, 18H, SiMe3), 6.45 (pt,
,
sym], 1487 (m)
The synthesis and work-up procedures are identical with the
one described for the preparation of 2 (393 mg (1.00 mmol) of
[Ti]Cl2 (1), 136 mg (1.00 mmol) of HOC6H4-4-C(O)Me, 100 mL of
diethyl ether, and 0.15 mL of Et2NH). Yield: 460 mg (0.95 mmol,
95% based on 1); orange-red solid.
[
[
mC–C
,
,
, asym], 1587 (s)
mN–O
,
3
4
JHH = 2.3 Hz, 4H, C5H4), 6.59 (dd, JHH = 9.1 Hz, JHH = 2.5 Hz, 4H,
3
C6H4), 6.63 (pt, JHH = 2.3 Hz, 4H, C5H4), 8.19 (dd, JHH = 9.1 Hz,
4JHH = 2.5 Hz, 4H, C6H4). 13C{1H} NMR (CDCl3): [d] ꢁ0.5 (SiMe3),

S. Köcher et al. / Journal of Organometallic Chemistry 693 (2008) 3213–3222
3221
115.8 (CH/C5H4), 117.8 (CH/C6H4), 126.1 (CH/C6H4), 126.8 (CH/
References
C5H4), 131.2 (iC/C5H4), 139.4 (iC/C6H4), 174.8 (C–OTi). Anal. Calc.
for C28H34N2O6Si2Ti (598.62): C, 56.18; H, 5.72; N, 4.68. Found: C,
56.43; H, 5.71; N, 4.38%.
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4.2.13. Synthesis of ([Ti]Cl)2(l-OC6H4O) (14)
The synthesis and work-up procedures are identical with the
one described for the preparation of 2 (393 mg (1.00 mmol) of
[Ti]Cl2 (1), 55 mg (0.50 mmol) of C6H4(OH)2-1,4, 150 mL of diethyl
ether, and 0.20 mL of Et2NH). Yield: 390 mg (0.47 mmol, 95% based
on 1); purple solid.
M.p.: [°C] 96 (dec.). 1H NMR (CDCl3): [d] 0.22 (s, 36H, SiMe3),
6.35 (pt, JHH = 2.4 Hz, 8H, C5H4), 6.54 (s, 4H, C6H4), 6.57 (pq,
JHH = 2.1 Hz, 4H, C5H4), 6.65 (pq, JHH = 2.1 Hz, 4H, C5H4). 13C{1H}
NMR (CDCl3): [d] ꢁ0.2 (SiMe3), 115.5 (CH/C5H4), 116.5 (CH/C6H4),
118.3 (CH/C5H4), 125.9 (CH/C5H4), 127.9 (iC/C5H4), 128.3 (CH/
C5H4), 166.1 (C–OTi). Anal. Calc. for C38H56Cl2O2Si4Ti2 (823.93): C,
55.40; H, 6.85. Found: C, 54.95; H, 7.10%.
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4.2.14. Synthesis of ([Ti](Cl)(l-OC6H4-4))2 (15)
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The synthesis and work-up procedures are identical with the
one described for the preparation of 2 (393 mg (1.00 mmol) of
[Ti]Cl2 (1), 93 mg (0.50 mmol) of HOC6H4-C6H4OH, 150 mL of
diethyl ether, and 0.20 mL of Et2NH). Yield: 430 mg (0.48 mmol,
96% based on 1); red solid.
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4
3
6.36 (dt, JHH = 1.90 Hz, JHH = 3.00 Hz, 4H, C5H4), 6.44 (dt,
4JHH = 1.90 Hz, JHH = 3.00 Hz, 4H, C5H4), 6.56 (dt, JHH = 3.00 Hz,
3
3
4JHH = 1.90 Hz, 4H, C5H4), 6.68 (dd, JHH = 8.4 Hz, JHH = 1.8 Hz, 4H,
3
4
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3
4
C6H4), 6.69 (dt, JHH = 3.00 Hz, JHH = 1.90 Hz, 4H, C5H4), 7.45 (dd,
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3JHH = 8.4 Hz, JHH = 1.8 Hz, 4H, C6H4). 13C{1H} NMR (CDCl3): [d]
4
ꢁ0.2 (SiMe3), 114.5 (CH/C5H4), 117.1 (CH/C6H4), 118.5 (CH/C5H4),
126.4 (CH/C5H4), 126.7 (CH/C6H4), 128.6 (iC/C5H4), 129.2 (CH/
C5H4), 132.4 (iC/C6H4), 170.3 (C–OTi). Anal. Calc. for C44H60Cl2O2Si4-
Ti2 (899.93): C, 58.72; H, 6.72. Found: C, 58.70; H, 6.98%.
4.2.15. X-ray structure determination
X-ray structure measurements were performed with a Bruker
Smart CCD equipment (Table 3) using Mo K
a radiation. Reflections
were collected in the -scan mode. All data were corrected for
x
(b) H.-M. Gau, C.-C. Schei, C.-K. Liu, L.-H. Luh, J. Organomet. Chem. 435 (1992)
43.
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absorption using SADABS [38]. The structures were solved by direct
methods using SHELXS-97 [39] and refined by full-matrix least-
square procedures on F2 using SHELXL-97 [40]. All non-hydrogen
atoms were refined anisotropically. The hydrogen atoms have been
refined using ideal positions to their neighbored atoms (4, 12, 13)
or were taken from the electron density difference map and refined
freely in their positions (5, 9, 11). The nitro group in 12 is
disordered and has been refined to split occupancies of 0.42/0.58
(O2–O3). The structure plots were performed with the PLATON pro-
gram. [41] The figure(s) in parenthesis after each calculated value
represents the standard deviation in units of the last significant
digit.
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5. Supplementary material
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Organomet. Chem. 592 (1999) 265.
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1013.
CCDC 686172, 686170, 686173, 686174, 686169 and 686171
contain the supplementary crystallographic data for 4, 5, 9, 11,
12 and 13. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
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Acknowledgements
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