1-Methylimidazol-2-yl-functionalized cyclopentadienyl titanium and zirconium complexes. Crystal structure of [η 5:η1- C5H4CPh2CH2-(1-MeC3H 2N2)]TiCl3

Article abstract of DOI:10.1007/s11172-006-0456-z

The new side-chain functionalized cyclopentadienyl ligand LiC ₅H₄CPh₂CH₂R (R is 1-methylimidazol-2-yl) as lithium salt 2, the trimethylsilyl derivative Me ₃SiC₅H₄CPh₂CH₂R (3), and the ligand in the CH form (4) were prepared starting from 6,6-diphenylfulvene and 1,2-dimethylimidazole lithiated at the 2-Me group (1) and then characterized. The half-sandwich complexes (η⁵:η ¹-C₅H₄CPh₂CH₂R)TiCl ₃ (5) and (η⁵:η ¹-C₅H ₄CPh₂CH₂R)ZrCl₃ (6) were synthesized. The molecular structure of complex 5 was established by X-ray diffraction. Complexes 5 and 6 exhibit dynamic behavior in solution associated with degenerate interconversion of the pseudo-six-membered metallacycle. For titanium complex 5 in a solvating solvent, a dynamic process due to intramolecular dissociation-coordination of the imidazole fragment was observed.

Full text of DOI:10.1007/s11172-006-0456-z

Russian Chemical Bulletin, International Edition, Vol. 55, No. 9, pp. 1574—1580, September, 2006
1574
1ꢀMethylimidazolꢀ2ꢀylꢀfunctionalized cyclopentadienyl
titanium and zirconium complexes. Crystal structure
of [η5:η1ꢀC5H4CPh2CH2ꢀ(1ꢀMeC3H2N2)]TiCl3
D. P. Krut´ko,aꢀ M. V. Borzov,a,b Long Yu Liao,a Wan Li Nie,b A. V. Churakov,c
J. A. K. Howard,d and D. A. Lemenovskiia
aDepartment of Chemistry, M. V. Lomonosov Moscow State University,
1 Leninskie Gory, 119992 Moscow, Russian Federation.
Fax: +7 (495) 932 8846. Eꢀmail: kdp@org.chem.msu.ru; dali@org.chem.msu.ru
bDepartment of Chemistry, Northwest University,
229 Bei Taibai Road, Xi'an, Shaanxi 710069, China.
cN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
31 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (495) 954 1279. Eꢀmail: churakov@igic.ras.ru
dDepartment of Chemistry, University of Durham,
South Road, Durham DH1 3LE, UK.
Fax: +44 (191) 384 4737. Eꢀmail: j.a.k.howard@durham.ac.uk
The new sideꢀchain functionalized cyclopentadienyl ligand LiC5H4CPh2CH2R (R is
1ꢀmethylimidazolꢀ2ꢀyl) as lithium salt 2, the trimethylsilyl derivative Me3SiC5H4CPh2CH2R
(3), and the ligand in the CH form (4) were prepared starting from 6,6ꢀdiphenylfulvene and
1,2ꢀdimethylimidazole lithiated at the 2ꢀMe group (1) and then characterized. The halfꢀ
5
1
5
1
sandwich complexes (η :η ꢀC5H4CPh2CH2R)TiCl3 (5) and (η :η ꢀC5H4CPh2CH2R)ZrCl3
(6) were synthesized. The molecular structure of complex 5 was established by Xꢀray diffracꢀ
tion. Complexes 5 and 6 exhibit dynamic behavior in solution associated with degenerate
interconversion of the pseudoꢀsixꢀmembered metallacycle. For titanium complex 5 in a solvatꢀ
ing solvent, a dynamic process due to intramolecular dissociation—coordination of the imidꢀ
azole fragment was observed.
Key words: zirconium, titanium, cyclopentadienyl ligands, imidazole, intramolecular coꢀ
ordination, NMR spectroscopy, Xꢀray diffraction analysis.
Group IV transition metal complexes with cycloꢀ
ZrIV complexes in which the imidazole fragment serves as
a side nitrogenꢀcontaining group (type IV, see Scheme 1).
As opposed to related compounds of type III, the presꢀ
ence of the second, "external," nitrogen atom, which is
involved in the conjugation system with the first nitrogen
atom, provides additional possibilities for control of the
nitrogen—metal coordination (for example, interconꢀ
versions of complexes IV and V) and "fine tuning" of the
πꢀdonorꢀacceptor and σꢀdonor properties of the coordiꢀ
nating nitrogen atom.
The imidazole ligands seldom occur in organometallic
chemistry of Group IV metals, and publications on such
complexes are few.25—28 The aim of the present study was
to synthesize new halfꢀsandwich titanium(IV) and zircoꢀ
nium(IV) complexes with the 2ꢀ(1ꢀmethylimidazolꢀ2ꢀyl)ꢀ
1,1ꢀdiphenylethylcyclopentadienyl ligand and investigate
their structures in the crystalline state and in solution.
pentadienyl ligands bearing a nitrogenꢀcontaining nꢀdoꢀ
nor moiety in the side chain have been extensively studied
(see the reviews1—4) and still attract considerable attenꢀ
tion.5—14 In most known complexes of this type, the niꢀ
trogen atom is bound to aliphatic substituents and is eiꢀ
ther in the sp3ꢀhybridized state (N→M coordination bond,
type I, Scheme 1) or is transformed into the sp2ꢀhybridꢀ
ized state through additional donation of the lone elecꢀ
tron pair to the metal atom (soꢀcalled geometry conꢀ
strained complexes, type II, see Scheme 1). Complexes in
which the coordination interaction with the metal atom
occurs through the sp2ꢀhybridized nitrogen atom (type III,
see Scheme 1) are few in number and these are primarily
pyridine or quinoline systems.9,15—24
Taking into account all mentioned above, it was of
interest to synthesize and study halfꢀsandwich TiIV and
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1518—1524, September, 2006.
1066ꢀ5285/06/5509ꢀ1574 © 2006 Springer Science+Business Media, Inc.

Cyclopentadienyl Ti and Zr complexes
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 9, September, 2006
1575
Scheme 1
Scheme 2
Results and Discussion
Synthesis of ligands
i. Hexane—diethyl ether.
and their trimethylsilyl derivatives
Cyclopentadienyl zirconium and
titanium complexes
The lithium salt of the [2ꢀ(1ꢀmethylimidazolꢀ2ꢀyl)ꢀ
1,1ꢀdiphenylethyl]cyclopentadienyl ligand (2) was synꢀ
thesized starting from metallated 1,2ꢀdimethylimidazole
(1) and 6,6ꢀdiphenylfulvene (Scheme 2). Imidazole 1
lithiated at the 2ꢀmethyl group was isolated in pure state
and characterized by 1H and 13C NMR spectroscopy.
Attempts to use fulvenes containing hydrogen atoms at
position 7 (for example, 6,6ꢀdimethylfulvene) as the startꢀ
ing compounds did not give good results because the reꢀ
action was accompanied by deprotonation at this position
and efforts to separate the resulting mixtures of lithium
isopropenylcyclopentadienide and the target product of
type 2 failed.
Halfꢀsandwich titanium and zirconium complexes (5
and 6, respectively) were synthesized from silane 3 and the
corresponding transition metal tetrachloride (Scheme 3).
Both compounds were isolated in good yields and characꢀ
terized by 1H and 13C NMR spectroscopy (including lowꢀ
temperature spectroscopy) and elemental analysis. The
molecular structure of titanium complex 5 was established
by Xꢀray diffraction.
Scheme 3
Silylation and protonation reactions of cycloꢀ
pentadienide 2 occur readily under treatment with triꢀ
methylchlorosilane or methanol, respectively, to give siꢀ
lane 3 (major isomer) or cyclopentadiene 4 (two isoꢀ
mers, 4a and 4b). The resulting products are crystalꢀ
lizable oils that decompose on heating. 6,6ꢀDipheꢀ
nylfulvene is one of decomposition products. The
structures of these compounds were established
by 1H (including NOE difference spectra) and 13C NMR
spectroscopy, mass spectrometry, and elemental
analysis.W
M = Ti (5), Zr (6)
Reaction conditions and yields: toluene; the yields were 64% (5)
and 71% (6).

1576
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 9, September, 2006
Krut´ko et al.
bond lengths characteristic of imidazole titanium comꢀ
plexes (2.131—2.246 Å, Cambridge Structural Database,31
January 2006 release). The imidazole ring is planar within
0.004(2) Å.
C(24)
C(23)
C(13)
C(25)
C(22)
C(21)
C(6)
C(12)
NMR spectroscopy studies on the dynamic behavior
of complexes 5 and 6 in solution
C(14)
C(15)
C(26)
C(2)
Dynamic processes in solutions of halfꢀsandwich
complexes 5 and 6 were studied by lowꢀtemperature
NMR spectroscopy. The temperature dependence of the
1H NMR spectra of a solution of complex 6 in THFꢀd8 is
shown in Fig. 2.
C(3)
C(11)
C(16)
C(4)
C(5)
C(1)
Cl(3)
C(7)
At 55 °C, complex 6 has the pseudosymmetry Cs, which
disappears as the temperature is lowered due to a deꢀ
crease in the rate of inversion of the sixꢀmembered
metallacycle —Zr—Cp—CPh2—CH2—C—N—. Earꢀ
lier, we have observed analogous processes for the
(C5Me4CH2CH2SMe)ZrCl3 (see Ref. 32) and
(C5Me4CH2CH2NMe2)ZrCl3 complexes.12 At –60 °C,
(the slow exchange limit), pairs of the signals for the
protons of the cyclopentadienyl ring are nonequivalent,
as well as the signals of the both Ph groups and the H atoms
of the methylene fragment. At this temperature, the
13C NMR spectrum shows the nonequivalence of the C(2),
C(5) and C(3), C(4) atoms and two Ph substituents. The
inversion barrier of the metallacycle ∆G≠ estimated from
the coalescence temperatures of the methylene protons
and the oꢀprotons of the Ph rings is 52.6 0.9 kJ mol–1
C(8)
N(2)
Cl(2)
Ti
N(1)
C(9)
C(20)
Cl(1)
C(10)
Fig. 1. Molecular structure of complex 5.
Crystal structure of titanium complex 5
The coordination polyhedron of complex 5 is a tetꢀ
ragonal pyramid (a fourꢀlegged piano stool) with the
Cp ring occupying the apex position (Fig. 1). Selected
bond lengths and bond angles are given in Table 1. In
general, the geometric parameters of 5 are similar to those
determined earlier for other titanium complexes with
functionalized chelating cyclopentadienyl ligands.29,30
The Ti—N(1) bond length (2.163(2) Å) is in the range of
for the protons of CH2 (Tcoal
= –20 °C) and
52.7 0.9 kJ mol–1 for the oꢀprotons (Tcoal = 0 °C). These
values are approximately 8 kJ mol–1 higher than those in
the halfꢀsandwich complexes (C5Me4CH2CH2SMe)ZrCl3
(see Ref. 32) and (C5Me4CH2CH2NMe2)ZrCl3 (see
Ref. 12), which is apparently associated with higher steric
hindrance in complex 6.
Table 1. Selected bond lengths (d) and bond angles (ω) in the
structure of 5
The assignment of the signals of the cyclopentadienyl
ring was based on the fact that, in the case of slow exꢀ
change (–60 °C), the difference in the 1H and 13C chemiꢀ
cal shifts in the pairs H(2), H(5) and H(3), H(4) and in
the pairs C(2)H, C(5)H and C(3)H, C(4)H should be the
smaller the larger the distance between these atoms and
the substituent.12,32,33
A change in the chemical shifts in the 13C NMR specꢀ
tra of a solution of complex 6 in THF as the temperature
decreases from +55 °C to –60 °C is at most 0.5 ppm for
all signals (at –60 °C, it is necessary to calculate the
average values for the corresponding pairs of the signals:
ipsoꢀC, C(2)H, C(5)H and C(3)H, C(4)H). This is unꢀ
ambiguous evidence that the coordination of the imidꢀ
azole ligand to the Zr atom is retained throughout the
temperature range under study even in a solvating solvent.
The dynamic behavior of titanium complex 5 in a
THFꢀd8 solution differs cardinally from that of the zircoꢀ
nium analog. A decrease in the temperature down to
Bond
d/Å
Angle
ω/deg
Ti—N(1)
Ti—Cl(3)
Ti—Cl(2)
Ti—Cl(1)
2.163(2)
2.3340(8)
2.3486(8)
2.3513(8)
2.034(1)
1.329(3)
1.388(3)
1.351(3)
1.380(3)
1.472(4)
1.338(4)
N(1)—Ti—Cl(2)
N(1)—Ti—Cl(3)
Cl(3)—Ti—Cl(2)
N(1)—Ti—Cl(1)
Cl(2)—Ti—Cl(1)
Cl(3)—Ti—Cl(1)
C(8)—N(1)—C(9)
C(8)—N(1)—Ti
C(9)—N(1)—Ti
C(8)—N(2)—C(10)
C(8)—N(2)—C(20)
140.05(6)
81.19(6)
86.01(3)
79.24(6)
86.06(3)
138.52(3)
106.2(2)
131.1(2)
119.4(2)
107.8(2)
126.7(2)
Ti—Pl*
N(1)—C(8)
N(1)—C(9)
N(2)—C(8)
N(2)—C(10)
N(2)—C(20)
C(9)—C(10)
C(10)—N(2)—C(20) 125.3(2)
N(1)—C(8)—N(2)
N(1)—C(8)—C(7)
N(2)—C(8)—C(7)
C(10)—C(9)—N(1)
C(9)—C(10)—N(2)
110.0(2)
127.3(2)
122.7(2)
109.6(2)
106.5(2)
* Pl is the mean plane of the cyclopentadienyl ring.

Cyclopentadienyl Ti and Zr complexes
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 9, September, 2006
1577
THF
NMe
H(2),
H(5)
mꢀ,pꢀCH
H(3),
H(4)
CH2
=CHN
=CHN
oꢀCH
THFꢀd7
55 °C
30 °C
10 °C
0 °C
–10 °C
–20 °C
–30 °C
–40 °C
–50 °C
H(2),
H(5)
H(3),
H(4)
mꢀ,pꢀCH
oꢀCH
=CHN
NMe
–60 °C
=CHN
CH2
7.0
6.5
4.0
3.5
3.0
δ
Fig. 2. Temperature dependence of the 1H NMR spectra of a solution of complex 6 in THFꢀd8.
–85 °C leads to a strong broadening of all signals in the
1H NMR spectrum, including the signals of the Me group
and the imidazole protons. The lower the temperature,
the larger the broadening. This fact can be attributed only
to a decrease in the rate of reversible coordination—disꢀ
sociation of the imidazole moiety toward the titaꢀ
nium atom.
CD2Cl2 is analogous to that of zirconium complex 6 in
THFꢀd8. However, even at –85 °C the slow exchange
limit is not achieved for all signals, which is accounted for
by two factors. First, this is a decrease in the difference
between the chemical shifts for the corresponding pairs of
nonequivalent protons as the rate of inversion of the
metallacycle decreases. For example, this difference for
the methylene group (an AB system) is no larger than
10 Hz (in complex 6, the corresponding parameter is
To the contrary, the dynamic behavior of halfꢀsandꢀ
wich titanium complex 5 in the nonsolvating solvent

1578
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 9, September, 2006
Krut´ko et al.
1
32 Hz). Second, the inversion barrier (∆G≠ = 45.2 1.3
kJ mol–1) estimated from the coalescence temperatures
of the H(2) and H(5) protons of the Cp ring and the
oꢀprotons of the Ph rings is almost 8 kJ mol–1 lower than
that in complex 6.
(98%). H NMR (30 °C, THFꢀd8), δ: 1.53 (s, 2 H, CH2); 2.96
(s, 3 H, Me); 5.98 and 6.14 (both d, 1 H each, NCH=CHN,
3JH,H = 1.2 Hz). 13C—{1H} NMR, δ: 23.42 (CH2); 32.17 (Me);
111.32, 123.81 (=CH); 166.15 (=NCN).
Lithium [2ꢀ(1ꢀmethylimidazolꢀ2ꢀyl)ꢀ1,1ꢀdiphenylethyl]cycloꢀ
pentadienide (2). Compound 1 (0.55 g, 5.38 mmol) was added
with cooling and stirring to a red solution of 6,6ꢀdiphenylfulvene
(1.23 g, 5.33 mmol) in THF (20 mL). The reaction mixture
immediately turned darkꢀgreen. Then the solution was heated at
35—45 °C for 2 days. The course of the reaction was monitored
by 1H NMR spectroscopy (a reference sample in THFꢀd8). The
solution was concentrated to dryness to obtain a residue as a
green foam that solidified and is soluble in diethyl ether and
toluene. To completely remove THF, the dry residue was disꢀ
solved in toluene (20 mL) and the solvent was again removed.
The product was washed with hexane (3×20 mL) and dried
in vacuo. The adduct 2•1.5THF was obtained as a paleꢀgreen
Therefore, the results of the present study suggest
that coordination of the imidazole group to the Zr atom
in complex 6 even in a solvating solvent is retained
throughout the temperature range under investigation.
For halfꢀsandwich titanium complex 5, this coordinaꢀ
tion is observed in the nonsolvating solvent CD2Cl2. In
a THF solution, reversible coordination—dissociation
of the nitrogenꢀcontaining moiety with the metal atom
accompanied by the replacement of the imidazole fragꢀ
ment by the solvent molecule occurs. Both halfꢀsandꢀ
wich complexes are characterized by a decrease in the
rate of inversion of the sixꢀmembered metallacycle
—M—Cp—CPh2—CH2—C—N—, the inversion barrier
for M = Ti being almost 8 kJ mol–1 lower than that for Zr.
1
solid compound in a yield of 1.15 g (49%). H NMR (THFꢀd8,
30 °C), δ: 3.02 (s, 3 H, NMe); 3.68 (s, 2 H, CH2); 5.62 and 5.72
3+4
(both virt. t, 2 H, C5H4,
J
= 5.4 Hz); 6.60 and 6.74
H,H
(both d, 1 H, NCH=CHN, 3JH,H = 1.2 Hz); 7.00—7.30 (set of m,
10 H, Ph). 13C NMR, δ: 32.38 (q, NMe, 1JC,H = 140 Hz); 39.56
1
(t, CH2, JC,H = 129 Hz); 55.35 (s, CPh2); 103.33 and 105.02
Experimental
1
(both d, CH in C5H4, JC,H = 159 Hz); 120.68 (ddq, =C(5´)H,
1JC,H = 189 Hz, JC,H = 15.3 Hz, JC,H = 3.0 Hz); 123.22
2
3
1
All reactions were carried out and samples for NMR specꢀ
troscopy were prepared in allꢀsealed evacuated Schlenk vessels.
The solvents and their deuterated analogs were purified accordꢀ
ing to known procedures (THF and diethyl ether were purified
with sodium benzophenone ketyl; toluene and hexane, with a
Na/K alloy; CH2Cl2, with calcium hydride), degassed in vacuo
(residual pressure of noncondensable gases was 10–3 Torr), and
introduced into reaction vessels by vacuum recondensation. Opꢀ
erations with volatile reagents (MeI (over CaH2), Me3SiCl (over
an Al powder), and methanol (over MgOMe) were carried
out analogously. The starting reagent 1,2ꢀdimethylimidazole
(Merck) was purified under reduced pressure, and the fraction
that crystallized at room temperature was collected. 6,6ꢀDiꢀ
phenylfulvene was prepared according to a known procedure;34
TiCl4 was heated with a freshly reduced finely dispersed copper
and recondensed in vacuo; ZrCl4 was purified by sublimation
under a stream of dry hydrogen.
(s, C5H4); 125.65 (d, pꢀCH, JC,H = 159 Hz); 126.56 (dd,
1
2
=C(4´)H, JC,H = 188 Hz, JC,H = 9.7 Hz); 127.50 (d, mꢀCH,
1JC,H = 158 Hz); 129.87 (d, oꢀCH, JC,H = 157 Hz); 149.13
1
(s, =NCN); 151.63 (s, ipsoꢀC). The atomic numbering scheme
is shown in Scheme 2.
Trimethylsilyl[2ꢀ(1ꢀmethylimidazolꢀ2ꢀyl)ꢀ1,1ꢀdiphenylꢀ
ethyl]cyclopentadiene (3). Solutions of compound 2 (1.13 g,
2.57 mmol) and Me3SiCl (0.35 mL, 0.30 g, 2.76 mmol) in THF
(the total volume was 20 mL) were mixed under cooling. The
mixture was allowed to warm up to room temperature and then
kept for 16 h. The solvent was removed, the yellow residue (an
oil that solidified) was dissolved in hexane (15 mL) and filtered
off from LiCl that precipitated, hexane was removed, and the
residue was dried in vacuo (10–3 Torr). Compound 3 was obꢀ
tained as a red oil that solidified in a yield of 0.77 g (69%).
Found (%): C, 78.20; H, 7.59; N, 6.88. C26H30N2Si. Calcuꢀ
lated (%): C, 78.34; H, 7.59; N, 7.03. 1H NMR (C6D6, 30 °C),
δ: –0.10 (s, 9 H, SiMe3); 2.04 (s, 3 H, NMe); 3.20 (s, 1 H,
C(5)H); 3.58 (A part of the AB system, 1 H, CHH, JH,H
14.5 Hz); 3.90 (B part of the AB system, 1 H, CHH, JH,H
14.5 Hz); 6.15 (d, 1 H, =C(5´)H, JH,H = 1.1 Hz); 6.36 (br.s,
1 H, =CH(4)); 6.56 (s, 1 H, =CH(1)); 6.57 (d, 1 H, =C(3)H,
3JH,H = 3.8 Hz); 6.98—7.47 (set of m, 10 H, Ph); 7.00 (d, 1 H,
1
The H and 13C NMR spectra were recorded on a Bruker
2
Avanceꢀ400 spectrometer at 400 and 100 MHz, respectively,
with the chemical shifts of Me4Si or residual protons of the
corresponding deuterated solvents (5.32 and 53.8 ppm for
CD2Cl2, 7.15 and 128.0 ppm for C6D6, 1.73 and 25.3 ppm for
THFꢀd8) as the internal standard. The detector temperature was
calibrated with a standard methanol sample.
=
=
2
3
3
=C(4´)H, JH,H = 1.1 Hz). Nuclear Overhauser effects (%):
The mass spectra were recorded on a Finnigan MAT
SSQ 7000 GLCꢀmassꢀspectrometer.
η
η
NMe(=C(5´)H)
=
1.6;
η
=C(4´)H(=C(5´)H)
=
6.6;
(NMe) = 2.2; η=C(5´)H(NMe) = 2.4. 13C—{1H} NMR, δ:
CH
2
Elemental analysis was performed on an automated Carlo
Erba analyzer.
–1.80 (SiMe3); 31.00 (NMe); 36.46 (CH2); 50.66 (C(5)H in
C5H4); 55.94 (CPh2); 119.69 (=C(5´)H); 126.14, 126.27 (pꢀCH
in Ph); 127.65, 127.69 (mꢀCH in Ph); 127.91 (=C(4´)H); 129.52,
133.07, 133.21 (=CH in C5H4); 130.00, 130.04 (oꢀCH in Ph);
144.84 (=NCN); 146.68, 146.76 (ipsoꢀC in Ph); 151.30 (=C(2)
in C5H4). The atomic numbering scheme for the major isomer is
shown in Scheme 2. MS (GC/MS, EI, 70 eV), m/z (Irel (%)):
326 [M – Me2SiCH2]+ (13.6), 303 [M – C3N2H2MeCH2]+
(20.7), 302 [M – C3N2H2Me2]+ (95.0), 231 [C5H5CPh2]+ (30.6),
230 [C5H4CPh2]+ (12.7), 153 [C5H4CPh]+ (10.6), 96
(1ꢀMethylimidazolꢀ2ꢀyl)methyllithium (1). A 2.45 М BunLi
solution in hexane (13.5 mL, 33.1 mmol) was slowly added
under cooling (–30—–10 °C) and vigorous stirring to a suspenꢀ
sion of 1,2ꢀdimethylimidazole (3.13 g, 32.56 mmol) in diethyl
ether (70 mL). The voluminous white precipitate that formed
was filtered off from the yellow solution, washed on a filter with
diethyl ether (3×20 mL), and dried in vacuo. Compound 1 was
obtained as a fine white crystalline powder in a yield of 3.28 g

Cyclopentadienyl Ti and Zr complexes
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 9, September, 2006
1579
[C3N2H2Me2]+ (100), 95 [C3N2H2MeCH2]+ (19.8), 73 [Me3Si]+
(65.3), 59 [Me2SiH]+ (14.6).
34.45 (NMe); 37.95 (CH2); 52.50 (CPh2); 120.07 (=C(5´)H);
124.89, 125.57 (CH in C5H4); 127.82 (pꢀCH); 128.39,
128.95 (mꢀ, oꢀCH); 129.22 (=C(4´)H); 144.61, 145.03, 145.05
(C in C5H4, =NCN, ipsoꢀC).
[2ꢀ(1ꢀMethylimidazolꢀ2ꢀyl)ꢀ1,1ꢀdiphenylethyl]cyclopentaꢀ
diene (4). A weighed sample of salt 2 (0.56 g, 1.28 mmol) was
dissolved in methanol (5 mL). Then methanol was evaporated,
and the residue was extracted with hexane (3×5 mL). The hexꢀ
ane solution was concentrated and yellow crystals of compound 4
were obtained. The product was dried in vacuo (10–3 Torr). The
yield was ~100%. Found (%): C, 84.53; H, 6.98; N, 8.38.
C23H22N2. Calculated (%): C, 84.63; H, 6.79; N, 8.58. 1H NMR
Single crystals of 5 suitable for Xꢀray diffraction were preꢀ
pared by slow recrystallization from dichloromethane.
5
1
{η :η ꢀNꢀ[2ꢀ(1ꢀMethylimidazolꢀ2ꢀyl)ꢀ1,1ꢀdiphenylethyl]ꢀ
5
1
cyclopentadienyl}trichlorozirconium, [η :η ꢀC5H4CPh2CH2ꢀ
(1ꢀMeC3H2N2)]ZrCl3 (6). A solution of silylated cyclopentaꢀ
diene 3 (0.90 g, 2.25 mmol) in toluene (5 mL) was added to a
suspension of ZrCl4 (0.52 g, 2.23 mmol) in the same solvent
(15 mL) under cooling (–20 °C) with vigorous stirring. After
stirring at –20 °C for 15 min, ZrCl4 was partially dissolved. The
mixture was allowed to gradually warm up to room temperature,
stirred for 2 h and then at 50 °C for 7 h, and kept for 16 h. The
precipitate was separated from the mother liquor by decantaꢀ
tion, washed with toluene (3×10 mL), and dried on a vacuum
line. Complex 6 was obtained in a yield of 0.83 g (71%).
Found (%): C, 52.57; H, 4.15; N, 5.06. C23H21Cl3N2Zr. Calcuꢀ
lated (%): C, 52.82; H, 4.05; N, 5.36. 1H NMR (THFꢀd8, 55 °C),
(C6D6, 30 °C), δ: for 4a: 1.91 (s, NMe); 3.34 (q, C(5)H2, 3JH,H
=
=
3
4JH,H = 1.3 Hz); 3.52 (s, CH2(7)); 6.12 (d, =C(5´)H, JH,H
1.0 Hz); 6.30 (m, =C(4)H); 6.39 (m, =C(3)H); 6.42
(m, =C(2)H); 6.99—7.37 (set of m, Ph); 7.02 (d, =C(4´)H,
3JH,H = 1.2 Hz); for 4b: 2.04 (s, NMe); 2.75 (q, C(5)H2, 3JH,H
=
=
3
4JH,H = 1.5 Hz); 3.68 (s, C(7)H2); 6.13 (d, =C(5´)H, JH,H
1.2 Hz); 6.17 (m, =C(4)H); 6.27 (m, =C(1)H); 6.39
(m, =C(3)H); 6.99—7.37 (set of m, Ph); 7.02 (d, =C(4´)H,
3JH,H = 1.2 Hz). Nuclear Overhauser effects (%) for 4a:
η
η
NMe(=C(5´)H)
=C(4)H(CH2(5)) = 0.5; η
=
0.2;
η
=C(4´)H(=C(5´)H)
=
0.8;
2(NMe) = 1.0; η=C(5´)H(NMe) =
δ: 2.89 (s, 3 H, NMe); 4.01 (s, 2 H, CH2); 6.43 (virt. t, 2 H,
C(7)H
3+4
2.1; for 4b: ηNMe(=C(5´)H) = 0.2; η=C(4´)H(=C(5´)H) = 0.8;
H(3), H(4),
J
= 5.7 Hz); 6.59 (virt. t, 2 H, H(2), H(5),
H,H
3+4
η
η
=C(4)H(CH2(5))
=
1.8;
η
=C(1)H(CH2(5))
=
2.0;
J
= 5.7 Hz); 6.79 and 7.46 (both d, 1 H, NCH=CHN,
H,H
(NMe) = 1.4; η=C(5´)H(NMe) = 1.3. 13C—{1H} NMR, δ:
3JH,H = 1.7 Hz); 6.95 (m, 4 H, oꢀCH); 7.17 (m, 6 H, mꢀ, pꢀCH).
13C—{1H} NMR (THFꢀd8, 55 °C), δ: 33.05 (NMe); 38.50 (CH2);
54.12 (CPh2); 116.88, 125.12 (CH in C5H4); 120.27 (=C(5´)H);
127.43 (pꢀCH); 128.78, 129.30 (mꢀ, oꢀCH); 130.69 (=C(4´)H);
133.64 (C in C5H4); 147.33 (ipsoꢀC); 148.90 (=NCN). 1H NMR
(THFꢀd8, –60 °C), δ: 2.83 (s, 3 H, NMe); 3.96 (A part of the
C(7)H
30.77,2 30.97 (NMe); 36.11, 36.78 (C(7)H2); 41.00, 43.02
(C(5)H2); 55.73, 56.77 (CPh2); 119.56, 119.62 (=C(5´)H);
126.38 (pꢀCH); 127.76 (mꢀCH); 127.92, 129.76, 131.60, 132.66,
133.16, 135.25 (=CH in C5H5); 128.07, 128.08 (=C(4´)H);
129.60, 129.98 (oꢀCH); 144.71, 144.76 (=NCN); 145.70, 146.93
(ipsoꢀC); 152.88, 154.71 (=C in C5H5). The atomic numbering
scheme is shown in Scheme 2 (4b : 4a = 1.15). MS (GC/MS,
EI, 70 eV), m/z (Irel (%)): 326 [M]+ (69.9), 231 [C5H5CPh2]+
(40.2), 153 [C5H4CPh]+ (20.8), 96 [C3N2H2Me2]+
(100), 95 [C3N2H2MeCH2]+ (9.2), 91 [C7H7]+ (5.5), 81
[C3N2H2Me]+ (7.1).
2
AB system, 1 H, CHH, JH,H = 13.5 Hz); 4.04 (B part of the
2
AB system, 1 H, CHH, JH,H = 13.5 Hz); 6.27 and 6.52
(both br.s, 1 H, H(3), H(4)); 6.37 and 6.79 (both br.s, 1 H, H(2),
H(5)); 6.54 and 7.07 (both m, 2 H, oꢀCH); 6.98 and 7.37 (both s,
1 H, NCH=CHN); 7.16 and 7.29 (both m, 1 H, pꢀCH); 7.29
and 7.35 (both m, 2 H, mꢀCH). 13C—{1H} NMR (THFꢀd8,
–60 °C), δ: 32.95 (NMe); 38.20 (CH2); 53.63 (CPh2); 113.39,
119.59 (C(2)H, C(5)H); 120.76 (=C(5´)H); 122.58, 127.66
(C(3)H, C(4)H); 127.51, 128.60, 129.01, 129.24, 129.44
(oꢀ, mꢀ, pꢀCH); 130.29 (=C(4´)H); 133.86 (C(1)); 144.93, 149.26
5
1
{η :η ꢀNꢀ[2ꢀ(1ꢀMethylimidazolꢀ2ꢀyl)ꢀ1,1ꢀdiphenylꢀ
5
1
ethyl]cyclopentadienyl}trichlorotitanium, [η :η ꢀC5H4CPh2CH2ꢀ
(1ꢀMeC3H2N2)]TiCl3 (5). Solutions of silylated cyclopentadiene
3 (1.02 g, 2.56 mmol) and TiCl4 (0.28 mL, 0.48 g, 2.55 mmol) in
toluene (the total amount was 10 mL) were mixed under cooling
(–78 °C) with vigorous stirring. The mixture was allowed to
gradually warm up to room temperature and stirred for 4 days,
after which a red oil poorly soluble in toluene was obtained.
After removal of volatile components and drying in vacuo, a new
portion of toluene (15 mL) was added, which caused crystallizaꢀ
tion of the oil. The red mother liquor was decanted, and the
yellowꢀorange crystalline precipitate was washed with toluene
(3×10 mL) and dried in vacuo. The yield of complex 5 was 0.79 g
(64%). Found (%): C, 57.57; H, 4.32; N, 5.70. C23H21Cl3N2Ti.
Calculated (%): C, 57.59; H, 4.41; N, 5.84. 1H NMR (THFꢀd8,
1
(ipsoꢀC); 148.59 (=NCN). H NMR (CD2Cl2, 30 °C), δ: 2.94
(s, 3 H, NMe); 3.88 (s, 2 H, CH2); 6.62 and 6.73 (both virt. t,
3+4
2 H, C5H4,
J
= 5.5 Hz); 6.70 and 7.58 (both d, 1 H,
H,H
3
NCH=CHN, JH,H = 1.5 Hz); 6.93 (m, 4 H, oꢀCH); 7.24 (m,
6 H, mꢀ, pꢀCH).
Xꢀray diffraction study of compound 5 was carried out on
an automated Bruker SMART 6K diffractometer at 120 K
(MoꢀKα radiation, λ = 0.71073 Å, graphite monochromator).
Crystals of 5 (C23H21Cl3N2Ti, M = 479.67) are monoclinic,
space group P21/c, a = 8.5730(7), b = 13.4748(13), c =
18.4369(17) Å, β = 99.790(3)°, V = 2098.8(3) Å3, Z = 4, dcalc
=
30 °C), δ: 3.36 (s, 3 H, NMe); 3.96 (s, 2 H, CH2); 6.92 (m, 4 H,
1.518 g cm–3, µ(MoꢀKα) = 0.803 mm–1, F(000) = 984. The
intensities of 13919 reflections (5068 independent reflections,
Rint = 0.0521) were measured using the ω scanning technique in
the angle range 2.24 < θ < 28.00° (–11 ≤ h ≤ 6, –17 ≤ k ≤ 17,
–24 ≤ l ≤ 24). The absorption correction was applied based on
the measured intensities of equivalent reflections.35 The strucꢀ
ture was solved by direct methods (SHELXSꢀ97).36 All nonꢀ
hydrogen atoms were refined anisotropically by the fullꢀmatrix
leastꢀsquares method against F 2 (SHELXLꢀ97).37 The positions
of all hydrogen atoms were located in difference electron denꢀ
sity maps and refined isotropically. The final R factors were
3
C5H4); 6.95 and 7.58 (both d, 1 H, NCH=CHN, JH,H
=
1.6 Hz); 7.05 (m, 4 H, oꢀCH); 7.20 (m, 6 H, mꢀ, pꢀCH).
13C—{1H} NMR (THFꢀd8) δ: 33.73 (NMe); 38.10 (CH2); 53.00
(CPh2); 120.27 (=C(5´)H); 124.13, 125.59 (CH in C5H4); 127.80
(pꢀCH); 129.03, 129.22 (mꢀ, oꢀCH); 129.60 (=C(4´)H); 144.73,
145.28, 146.30 (C in C5H4, =NCN, ipsoꢀC). 1H NMR (CD2Cl2,
30 °C), δ: 3.37 (s, 3 H, NMe); 3.88 (s, 2 H, CH2); 6.84 and 7.60
3
(both d, 1 H, NCH=CHN, JH,H = 1.6 Hz); 6.95 and 7.01
3+4
(both virt. t, 2 H, C5H4,
J
= 5.4 Hz); 6.97 (m, 4 H,
H,H
oꢀCH); 7.26 (m, 6 H, mꢀ, pꢀCH). 13C—{1H} NMR (CD2Cl2), δ:

1580
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 9, September, 2006
Krut´ko et al.
R1 = 0.0474 and wR2 = 0.1150 for 3510 reflections with I > 2σ(I );
658 parameters were refined; GOOF = 0.969, ∆ρ (min/max) =
18. T. Dreier, R. Fröhlich, and G. Erker, J. Organomet. Chem.,
2001, 621, 197.
19. M. Enders, R. Rudolph, and H. Pritzkow, Chem. Ber., 1996,
129, 459.
–0.522/0.816 e•Å–3
.
20. M. Enders, R. Rudolph, and H. Pritzkow, J. Organomet.
Chem., 1997, 549, 251.
21. T. J. Clark, T. A. Nile, D. McPhail, and A. McPhail, Polyꢀ
hedron, 1989, 8, 1804.
22. Y. Qian, J. Guo, J. Huang, and Q. Yang, Polyhedron, 1997,
16, 195.
This study was financially supported by the Russian
Science Support Foundation.
References
23. G. Paolucci, G. Pojana, J. Zanon, V. Lucchini, and
E. Avtomonov, Organometallics, 1997, 16, 5312.
24. J. W. Pattiasina, F. van Bolhuis, and J. H. Teuben, Angew.
Chem., 1987, 99, 342.
25. D. Rottger, G. Erker, R. Fröhlich, and S. Kapira,
J. Organomet. Chem., 1996, 518, 17.
26. D. Vagedes, G. Erker, and R. Fröhlich, J. Organomet. Chem.,
2002, 641, 148.
27. T. Ishiyama, T. Mizuta, K. Miyoshi, and H. Nakazawa,
Organometallics, 2003, 22, 1096.
1. P. Jutzi and U. Siemeling, J. Organomet. Chem., 1995,
500, 175.
2. P. Jutzi and T. Redeker, Eur. J. Inorg. Chem., 1998, 663.
3. C. Müller, D. Vos, and P. Jutzi, J. Organomet. Chem., 2000,
600, 127.
4. Y. Qian, J. Huang, M. D. Bala, B. Lian, H. Zhang, and
H. Zhang, Chem. Rev., 2003, 103, 2633.
5. P. B. Hitchcock, G. L. Jeffery, and M. Togrou, J. Organomet.
Chem., 2003, 669, 101.
6. V. V. Kotov, R. Fröhlich, G. Kehr, and G. Erker,
J. Organomet. Chem., 2003, 676, 1.
7. S. Döring, V. V. Kotov, G. Erker, G. Kehr, K. Bergander,
O. Kataeva, and R. Fröhlich, Eur. J. Inorg. Chem.,
2003, 1599.
28. S. P. Downing and A. A. Danopoulos, Organometallics, 2006,
25, 1337.
29. D. P. Krut´ko, M. V. Borzov, E. N. Veksler, A. V. Churakov,
and K. Mach, Polyhedron, 2003, 22, 2885.
30. D. P. Krut´ko, M. V. Borzov, E. N. Veksler, and A. V.
Churakov, Izv. Akad. Nauk, Ser. Khim., 2005, 116 [Russ.
Chem. Bull., Int. Ed., 2005, 54, 117 (Engl. Transl.)].
31. F. H. Allen, Acta Crystallogr., Sect. B, 2002, B58, 380.
32. D. P. Krut´ko, M. V. Borzov, V. S. Petrosyan, L. G.
Kuz´mina, and A. V. Churakov, Izv. Akad. Nauk, Ser. Khim.,
1996, 984 [Russ. Chem. Bull., 1996, 45, 940 (Engl. Transl.)].
33. D. M. Roitershtein, D. P. Krut´ko, E. N. Veksler, D. A.
Lemenovskii, W. Nie, and C. Qian, Izv. Akad. Nauk, Ser.
Khim., 2001, 1234 [Russ. Chem. Bull., Int. Ed., 2001,
50, 1295].
34. J. L. Kice and F. M. Parham, J. Am. Chem. Soc., 1958,
80, 3792.
35. G. M. Sheldrick, SADABS, University of Göttingen,
Göttingen (Germany), 1997.
36. G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, A46, 467.
37. G. M. Sheldrick, SHELXLꢀ97, University of Göttingen,
Göttingen (Germany), 1997.
8. M. Enders, P. Fernandez, S. Mihan, and H. Pritzkow,
J. Organomet. Chem., 2003, 687, 125.
9. G. Paolucci, M. Vignola, L. Coletta, B. Pitteri, and
F. Benetollo, J. Organomet. Chem., 2003, 687, 161.
10. S. VenneꢀDunker, G. Kehr, R. Fröhlich, and G. Erker,
Organometallics, 2003, 22, 948.
11. G. Erker, G. Kehr, and R. Fröhlich, J. Organomet. Chem.,
2004, 689, 1402.
12. D. P. Krut´ko, M. V. Borzov, R. S. Kirsanov, M. Yu. Antipin,
and A. V. Churakov, J. Organomet. Chem., 2004, 689, 595.
13. S. Knuppel, C. Wang, G. Kehr, R. Frцhlich, and G. Erker,
J. Organomet. Chem., 2005, 690, 14.
14. M. A. Esteruelas, A. M. Lopez, A. C. Mateo, and E. Onate,
Organometallics, 2005, 24, 5084.
15. M. Blais, J. C. W. Chien, and M. D. Rausch, Organometalꢀ
lics, 1998, 17, 3775.
16. C. Qian, J. Guo, C. Ye, J. Sun, and P. Zeng, J. Chem. Soc.,
Dalton Trans., 1993, 3441.
17. Z. Ziniuk, I. Goldberg, and M. Kol, J. Organomet. Chem.,
1997, 545—546, 441.
Received May 2, 2006