Cationic cyclopentadienyl phenylenediamido titanium species generated by reaction of TiCpR[1,2-C6H4(NCH 2t-Bu)2]R (CpR = η5-C 5H5, η5-C5</su

Article abstract of DOI:10.1021/om051088y

The reaction of TiCp^R[1,2-C₆H₄(NNp) ₂]R with the Lewis acid B(C₆F₅)₃ in noncoordinating solvent affords the new zwitterionic species TiCp ^R[1,2-C₆H₄

Full text of DOI:10.1021/om051088y

Organometallics 2006, 25, 1723-1727
1723
Cationic Cyclopentadienyl Phenylenediamido Titanium Species
Generated by Reaction of TiCpR[1,2-C6H4(NCH2t-Bu)2]R (CpR )
η5-C5H5, η5-C5Me5; R ) CH3, CH2Ph) with B(C6F5)3. X-ray
Molecular Structure of
Ti(η5-C5Me5)[1,2-C6H4(NCH2t-Bu)2][µ-MeB(C6F5)3]†
Vanessa Tabernero,‡ Ma Carmen Maestre,‡ Gerardo Jime´nez,‡ Toma´s Cuenca,*,‡ and
Carmen Ram´ırez de Arellano*,§,
Departamento de Qu´ımica Inorga´nica, UniVersidad de Alcala´, Campus UniVersitario,
28871 Alcala´ de Henares. Spain, and Departamento de Qu´ımica Orga´nica, UniVersidad de Valencia,
46100, Valencia. Spain.
ReceiVed December 22, 2005
The reaction of TiCpR[1,2-C6H4(NNp)2]R with the Lewis acid B(C6F5)3 in noncoordinating solvent
affords the new zwitterionic species TiCpR[1,2-C6H4(NNp)2)][µ-RB(C6F5)3]. When the reaction is
performed in dichloromethane, the [µ-RB(C6F5)3]- anion is displaced by solvent molecules, giving ionic
products in which the anion is not coordinated. The cyclopentadienyl zwitterionic complexes TiCp[1,2-
C6H4(NNp)2)[µ-RB(C6F5)3] decompose via ligand scrambling between boron and titanium to give the
neutral titanium complex TiCp[1,2-C6H4(NNp)2](C6F5) along with the byproduct RB(C6F5)2. In contrast,
the pentamethylcyclopentadienyl analogues TiCp*[1,2-C6H4(NNp)2][µ-RB(C6F5)3] evolve through C-H
activation to yield an unresolved mixture of compounds. The molecular structure of TiCp*[1,2-C6H4-
(NNp)2][µ-MeB(C6F5)3] has been determined by X-ray diffraction methods.
As part of our interest in complexes bearing ligands that
incorporate nitrogen donors, such as cyclopentadienyl-amido,1-4
diamido,5,6 and alkoxo-amido,7 as potential precursors for new
olefin polymerization catalysts, we have recently reported the
synthesis of the chelating diamido complexes MCpR[1,2-C6H4-
(NR)2]X [M ) Ti, Zr; CpR ) Cp, Cp*, η5-C5H4(SiMe3); R )
Np, n-Pr; X ) Cl, Me, Bz].5,6 Upon treatment with methyl-
aluminoxane (MAO), these complexes initiate active ethylene
polymerization processes, in which the nature of the active
species was studied via stoichiometric reactions.6 The alkyl
complexes MCp[1,2-C6H4(NR)2]R are attacked by MAO at the
diamido ligand to give zwitterionic species active for ethylene
polymerization. In contrast, these titanium derivatives do not
show any catalytic activity in the presence of the widely used
boron-based cocatalysts B(C6F5)3 and [CPh3][B(C6F5)4]. In
probing these observations, we have studied the reaction of the
complexes TiCpR[1,2-C6H4(NNp)2]X (CpR ) Cp, Cp*; X )
Cl, Me, Bz) with B(C6F5)3 and [CPh3][B(C6F5)4] by NMR
spectroscopy in the absence of monomer, and the molecular
structure of TiCp*[1,2-C6H4(NNp)2][µ-MeB(C6F5)3] has been
determined by single-crystal X-ray diffraction.
On the basis of our earlier results from the reaction of MCp-
[1,2-C6H4(NR)2]R with MAO, the question of the determination
of the site of boron-based Lewis acid attack arises. Conse-
quently, as a first step, we studied the reaction of the chloro
derivate TiCp[1,2-C6H4(NNp)2]Cl (1a) with B(C6F5)3. In this
reaction, the titanium complex is recovered unaltered regardless
of the reaction conditions or solvent used, suggesting that in
further reactions with boron reagents the Ti-N bond of these
monocyclopentadienyl phenylenediamido alkyl complexes will
not be affected.
When C6D6 was added to mixtures of TiCpR[1,2-C6H4-
(NNp)2]R (Np ) CH2t-Bu; CpR ) Cp, R ) Me, 2a; Bz, 2b;
CpR ) Cp*, R ) Me, 3a; Bz, 3b) and B(C6F5)3 in an equimolar
ratio at room temperature, dark solutions were formed. This
reaction results in the selective abstraction of the alkyl ligand
to give the new zwitterionic titanium species TiCpR[1,2-C6H4-
(NNp)2)[µ-RB(C6F5)3] (CpR ) Cp, R ) Me, 4a; Bz, 4b; CpR
) Cp*, R ) Me, 5a; Bz, 5b) (Scheme 1), in contrast to the
attack observed on the diamido ligand when an aluminum
reagent is used.6 In view of such results, we propose that the
difference in selectivity between boron- and aluminum-based
reactions causes the difference in polymerization catalytic
behavior for compounds in this class.
† Dedicated to Jose´ Antonio Abad, an excellent chemist and better person.
* Corresponding authors. Tel: 34 91 8854655. Fax: 34 91 8854683.
E-mail: tomas.cuenca@uah.es.
‡ Universidad de Alcala´.
§ Universidad de Valencia.
Correspondence concerning the crystallographic data should be ad-
dressed to this author. E-mail: M.Carmen.Ramirezdearellano@uv.es.
(1) Cano, J.; Royo, P.; Lanfranchi, M.; Pellinghelli, M. A.; Tiripicchio,
A. Angew. Chem., Int. Ed. 2001, 40, 2495-2496.
(2) Jime´nez, G.; Royo, P.; Cuenca, T.; Herdtweck, E. Organometallics
2002, 21, 2189-2195.
(3) Jime´nez, G.; Rodr´ıguez, E.; Go´mez-Sal, P.; Royo, P.; Cuenca, T.;
Galakhov, M. Organometallics 2001, 20, 2459-2467.
(4) Maestre, M. C.; Tabernero, V.; Mosquera, M. E. G.; Jime´nez, G.;
Cuenca, T. Organometallics 2002, in press.
(5) Tabernero, V.; Cuenca, T.; Herdtweck, E. Eur. J. Inorg. Chem. 2004,
3154-3162.
(6) Tabernero, V.; Cuenca, T. Eur. J. Inorg. Chem. 2005, 338-346.
(7) Alesso, G. Doctoral Thesis, University of Alcala´ (Spain), 2006.
The NMR spectra recorded after reagent mixing show all
signals shifted downfield compared with those found for the
corresponding neutral titanium precursors as a consequence of
the high Lewis acidity of titanium metal after the formation of
1
the cation. The H NMR spectra of 4a and 5a show a broad
signal ascribed to the methyl group bonded to boron, supporting
the formation of the methylborate anion. Evidence for the
10.1021/om051088y CCC: $33.50 © 2006 American Chemical Society
Publication on Web 03/03/2006

1724 Organometallics, Vol. 25, No. 7, 2006
Tabernero et al.
Scheme 1
presence of the coordinated [RB(C6F5)3]- anion is provided by
the comparatively large 19F chemical shift difference ∆δ )
δ(m-F) - δ(p-F)8-10 (3.3, 4a; 3.5 4b; 4.7, 5a) observed in the
19F NMR spectra. The Me-B resonances appear at δ 0.41 for
4a and δ 0.58 for 5a. In compound 4b the [PhCH2B(C6F5)3]-
anion is coordinated to the metal center via the benzylic phenyl
group, as shown by the downfield 13C NMR resonance exhibited
by the ipso-carbon atom of the phenyl group (δ 159.6).11,12 The
solubility of all of these complexes in benzene is also consistent
with their zwitterionic character.
To establish the molecular geometry for this type of species,
single crystals of 5a suitable for X-ray diffraction were obtained
by slow evaporation from a benzene solution (Figure 1). The
crystal structure of 5a shows the titanium atom, which is
coordinated to the Cp* and the phenylenediamido ligands,
interacting with the methyl group of the borate anion. The
Ti‚‚‚B distance of 4.154(1) Å is within the Ti‚‚‚B distance range
(3.991-4.017 Å) found for the four Ti-methylborate zwiterionic
species TiCpMe(NP-t-Bu3)[µ-MeB(C6F5)3],13 Ti(NP-t-Bu3)2[µ-
MeB(C6F5)3]2,14 TiLMe[µ-MeB(C6F5)3] [L ) 1,1′-bis(trimeth-
ylsilylamido)ferrocene-N,N′],15 and Ti(L′)Me[µ-MeB(C6F5)3]
[L′ ) η5-(3-ethylindenyl-1-dimethylsilyl)-tert-butylamido]16
already reported.
The Ti-C(27) distance of 2.489(1) Å found for compound
5a is slightly longer than those found for the four reported
Ti‚‚‚CH3-B zwiterionic complexes (2.333-2.404 Å). This
could be a consequence of the steric crowding around the
titanium center in compound 5a. The Ti-C-B angle of
170.03(8)° found for compound 5a lies in the normal range for
similar derivatives (Ti‚‚‚C-B 167.2-175.0°). A structural
parameter study for Ti‚‚‚CH3-B interactions in the already
reported compounds has been made (see Figure 2 and Table
1). The borate methyl group hydrogen atom positions for
compound 5a were located in a difference Fourier synthesis
and freely refined. However, the symmetrical or unsymmetrical
nature of the Ti‚‚‚CH3-B interaction could not be established
Figure 1. Ellipsoid plot for the crystal structure of compound 5a.
Hydrogen atoms except for the methylborate group have been
omitted for clarity. Selected bond lengths (Å) and angles (deg):
Ti-N2 1.912(1), Ti-N1 1.918(1), Ti-C12 2.412(1), Ti-C11
2.419(1), Ti‚‚‚C27 2.489(1), N1-C11 1.3943(16), N1-C17
1.4688(15), N2-C12 1.3975(16), N2-C22 1.4648(15), C11-C12
1.4457(17), C12-C13 1.4195(17), C13-C14 1.3661(19), C14-
C15 1.4039(19), C15-C16 1.3729(19), C11-C16 1.4201(17),
B-C27 1.679(18), N2-Ti-N1 90.42(4), N2-Ti-C12 35.37(4),
N1-Ti-C11 35.15(4), C11-N1-C17 121.85(10), C11-N1-Ti
92.47(7), C12-N2-C22 121.31(10), C12-N2-Ti 92.25(7), C22-
N2-Ti 141.31(8), B-C27‚‚‚Ti 170.03(8).
Figure 2. Ellipsoid plot for the B-CH3‚‚‚Ti fragment. The
hydrogen atoms have been labeled from the shortest to the longest
C-H bond as A, B, and C, respectively.
due to the large uncertainties in the metrical data. The
unsymmetrical nature for the Ti‚‚‚CH3-B interaction has been
reported for compounds TiCpMe(NP-t-Bu3)[µ-MeB(C6F5)3]13
and Ti(NP-t-Bu3)2[µ-MeB(C6F5)3]2,14 whose hydrogen atoms
have been located in a difference Fourier synthesis and refined.
For these compounds one of the three Ti‚‚‚H interactions is
clearly longer and corresponds to the closest Ti‚‚‚H-C angle
(77-81°). On the other hand, the unsymmetrical nature of the
Ti‚‚‚CH3-B interaction for compounds TiLMe[µ-MeB(C6F5)3]15
(L ) 1,1′-bis(trimethylsilylamido)ferrocene-N,N′) and Ti(L′)-
Me[µ-MeB(C6F5)3]16 (L′ ) η5-(3-ethylindenyl-1-dimethylsilyl)-
tert-butylamido) cannot be established because it is not clear
how the H atom positions were located and the uncertainties in
the metrical data are not provided.
The internal structural parameters of the “Ti(1,2-C6H4-
(NNp)2)” metalacycle are essentially the same as those found
in the neutral precursors, which indicates that the phenylene-
diamido ligand is attached to the metal in a η2-N,N′-π manner.
However, there is a notable structural difference; whereas the
neutral precursors exist as the supine isomer,17,18 in 5a the
phenylenediamido ligand adopts a prono conformation. This fact
(8) Horton, A. D.; de With, J. Chem. Commun. 1996, 1375-1376.
(9) Horton, A. D.; de With, J.; van der Linden, A. J.; van der Weg, H.
Organometallics 1996, 15, 2672-2674.
(10) Wright, J. M.; Landis, C. R.; Ros, M.; Horton, A. D. Organome-
tallics 1998, 17, 5031-5040.
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1993, 12, 4473-4478.
(12) Pellecchia, C.; Grassi, A.; Immirzi, A. J. Am. Chem. Soc. 1993,
115, 1160-1162.
(13) Stephan, D. W.; Stewart, J. C.; Guerin, F.; Spence, R.; Xu, W.;
Harrison, D. G. Organometallics 1999, 18, 1116-1118.
(14) Guerin, F.; Stephan, D. W. Angew. Chem., Int. Ed. 2000, 39, 1298-
1300.
(15) Shafir, A.; Arnold, J. J. Am. Chem. Soc. 2001, 123, 9212-9213.
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L. J. Am. Chem. Soc. 2003, 125, 10788-10789.
(17) Yasuda, H.; Nakamura, A. Angew. Chem., Int. Ed. Engl. 1987, 26,
723-742.

Cationic Cyclopentadienyl Phenylenediamino Ti Species
Organometallics, Vol. 25, No. 7, 2006 1725
Table 1. Structural Parameters for the B-CH3‚‚‚Ti Agostic Interactions in Compounds 5a, TiCpMe(NP-t-Bu3)[µ-MeB(C6F5)3],13
Ti(NP-t-Bu3)2[µ-MeB(C6F5)3]2,14 (TiLMe(µ-MeB(C6F5)3) [L ) 1,1′-bis(trimethylsilylamido)ferrocene-N,N′]15 and
Ti(L′)[Me(µ-MeB(C6F5)3] [L′ ) η5-(3-ethylindenyl-1-dimethylsilyl)-tert-butylamido]16
compound
bond
C‚‚‚Ti (Å)
C-H (Å)
H‚‚‚Ti (Å)
C-H‚‚‚Ti (deg)
5a
C-H(A)
C-H(B)
C-H(C)
C-H(A)
C-H(B)
C-H(C)
C-H(A)
C-H(B)
C-H(C)
C-H(A)
C-H(B)
C-H(C)
C-H(A)
C-H(B)
C-H(C)
2.489(1)
2.489(1)
2.489(1)
2.404(4)
2.404(4)
2.404(4)
2.333(7)
2.333(7)
2.333(7)
2.297(4)
2.297(4)
2.297(4)
2.333
0.976(17)
0.987(18)
1.002(16)
0.931
0.945
1.012
0.801
0.992
1.013
0.944
2.358(17)
2.470(18)
2.240(16)
2.435(3)
2.197(3)
2.257(3)
2.219
2.205
2.351
2.122
2.321
86.1(11)
79.6(11)
92.3(10)
80.8
90.8
85.8
88.1
84.8
77.0
88.4
76.5
83.1
89.65
82.6
73.6
TiCpMe(NP-t-Bu3)[µ-MeB(C6F5)3]
Ti(NP-t-Bu3)2[µ-MeB(C6F5)3]2
TiLMe[µ-MeB(C6F5)3]
0.976
0.985
0.967
0.961
2.198
2.129
2.253
2.415
Ti(L′)Me[µ-MeB(C6F5)3]
2.333
2.333
0.960
Scheme 2
implies a conformational process associated with cationic
generation in the reactions of the neutral alkyl compounds with
the boron reagents. The presence of the sterically demanding
methylborate in the coordination sphere of the metal center
forces the phenylenediamido ligand to adopt the prone confor-
mation to minimize their steric interactions.
Similar reactions of TiCpR[1,2-C6H4(NNp)2]R and B(C6F5)3
in a chlorinated solvent (CDCl3 or CD2Cl2) did not lead to the
analogous zwitterionc species obtained in C6D6 but gave the
ionic products {TiCpR[1,2-C6H4(NNp)2](solvent)n}+[RB(C6F5)3]-
(CpR ) Cp, R ) Me, 6a; Bz, 6b; CpR ) Cp*, R ) Me, 7a; Bz,
7b) (Scheme 1), where the anion is displaced by an indetermi-
nate number of solvent molecules. The facile displacement of
the alkylborate anion from the coordination sphere by the
chlorinated solvent is in contrast to the behavior of TiMe(NP-
t-Bu3)2(µ-MeB(C6F5)3),19 which was recrystallized from di-
chloromethane without exchange of methylborate. This differ-
ence is attributed to the effect of the bulky and donating (up to
eight electrons) η4-phenylenediamido ligand. The noncoordi-
nating nature of the anions is deduced from the NMR spectro-
scopic data. In all cases, the 19F chemical shift difference ∆δ
) δ(m-F) - δ(p-F) (3.1, 6a; 2.7, 6b; 2.5, 7a, 7b) is in
accordance with a noncoordinated anion. Such free disposition
is further confirmed by the upfield shifted ipso-carbon reso-
nances of the benzylic groups (i.e., δ 148.6 for compound 6b).
Comparison of the spectroscopic data for the cationic fragment
of the compounds 6a,b and 7a,b shows slight changes due to
the different solvents and the nature of the counterion.
pathway of the cationic species depends on the CpR group. Thus,
the cyclopentadienyl derivatives decompose to give the neutral
pentafluorophenyl complex TiCp[1,2-C6H4(NNp)2](C6F5) (8)
along with the corresponding byproduct RB(C6F5)2 (Scheme
2).21 In this decomposition process, the formation of the chloro
complex TiCp[1,2-C6H4(NCH2t-Bu)2]Cl (1a) by chloro abstrac-
tion from the solvent was never observed. The ligand redistribu-
tion reaction between titanium and boron atoms occurs faster
for the methyl than for the benzyl anionic derivative and is
clearly influenced by the polarity of the solvent, being acceler-
ated in polar mediums. Similar reactivity has been described
for analogous cationic group 4 metal species derived from the
reaction of B(C6F5)3 with diamido complexes,22-27 although
systems containing diamido and cyclopentadienyl ligands exhibit
a higher proclivity for this type of reaction. To confirm the
formation of 8, this compound was synthesized by an alternative
procedure using the reaction of the chloro derivative TiCp[1,2-
C6H4(NNp)2]Cl with Li(C6F5) (generated in situ from C6F5Br
and n-BuLi) in hexane at -78 °C (Scheme 2). The permethy-
lated-cyclopentadienyl derivatives evolve through C-H activa-
Treatment of TiCp[1,2-C6H4(NNp)2]Me (2a) with [CPh3]-
[B(C6F5)4] in CD2Cl2 at 25 °C was studied by NMR spectros-
copy. The instantaneous generation of Ph3CCH3, as judged by
NMR spectroscopy,20 indicates the abstraction of the methyl
1
group initially attached to titanium. The H NMR spectrum
shows a set of resonances indicative of the formation of the
cationic fragment {TiCp[1,2-C6H4(NNp)2]}+.
All the cationic species described above are reasonably stable
in solution, even in chlorinated solvents, and decomposition at
room temperature is observed only very gradually. Reaction of
TiCpR[1,2-C6H4(NNp)2]R with B(C6F5)3 proceeds in an identical
fashion whether C6D6 or chlorinated solvents are used, regardless
of the nature of the CpR ligand. However, the decomposition
(21) Dagorne, S.; Guzei, I. A.; Coles, M. P.; Jordan, R. F. J. Am. Chem.
Soc. 2000, 122, 274-289.
(22) Go´mez, R.; Green, M. L. H.; Haggitt, J. L. J. Chem. Soc., Dalton
Trans. 1996, 939-946.
(23) Scollard, J. D.; McConville, D. H.; Rettig, S. J. Organometallics
1997, 16, 1810-1812.
(24) Scollard, J. D.; McConville, D. H.; Vittal, J. J. Organometallics
1997, 16, 4415-4420.
(18) Nakamura, A.; Mashima, K. J. Organomet. Chem. 2001, 621, 224-
230.
(19) Stephan, D. W.; Guerin, F.; Spence, R. E. V.; Koch, L.; Gao, X.
L.; Brown, S. J.; Swabey, J. W.; Wang, Q. Y.; Xu, W.; Zoricak, P.; Harrison,
D. G. Organometallics 1999, 18, 2046-2048.
(20) Lee, C. H.; La, Y. H.; Park, J. W. Organometallics 2000, 19, 344-
351.
(25) Go´mez, R.; Go´mez-Sal, P.; del Real, P. A.; Royo, P. J. Organomet.
Chem. 1999, 588, 22-27.
(26) Scollard, J. D.; McConville, D. H.; Vittal, J. J.; Payne, N. C. J.
Mol. Catal. A-Chem. 1998, 128, 201-214.
(27) Fenwick, A. E.; Phomphrai, K.; Thorn, M. G.; Vilardo, J. S.; Trefun,
C. A.; Hanna, B.; Fanwick, P. E.; Rothwell, I. P. Organometallics 2004,
23, 2146-2156.

1726 Organometallics, Vol. 25, No. 7, 2006
Tabernero et al.
0.022 mmol). The solution darkened, and an oily product along
with black crystals was soon observed. Checking the sample before
total precipitation of the product allowed us to obtain NMR data
for the desired cationic species. Anal. Calcd for C45H44N2TiBF15
(956.13 g/mol): C, 56.52; H, 4.60; N, 2.93. Found: C, 56.41; H,
4.33; N, 2.79. 1H NMR (300 MHz, C6D6, 25 °C): δ 7.11 (m, 2H,
Ph), 7.03 (m, 2H, Ph), 4.20 (br, 2H, CH2), 3.91 (br, 2H, CH2),
1.17 (s, 15H, C5Me5), 0.63 (s, 18H, t-Bu), 0.58 (s, 3H, BCH3).
13C{1H} NMR (75 MHz, C6D6, 25 °C): δ 128.6, 119.6 (Ph), 115.5
(ipso-C5Me5), 62.5 (CH2), 36.1 (ipso-t-Bu), 28.9 (t-Bu), 11.7
(BCH3), 10.5 (C5Me5), 150.7, 147.7, 140.7, 139.0, 136.0, (C6F5),
Cipso for Ph not observed. 19F NMR (282 MHz, C6D6, 25 °C): δ
-132.4 (br, o-C6F5), -161.1 (br, p-C6F5), -165.8 (br, m-C6F5),
∆δ (p, m-F) ) 4.7 ppm.
tion to yield an unresolved mixture of compounds (Scheme 2).
The bulkiness and the electronic properties of the Cp* ring play
a decisive role in the decomposition process. Recently, similar
conclusions based on theoretical studies have been published,
suggesting that the aryl group transfer reaction can be prevented
if bulky substituents on the ancillary ligand or methyl substit-
uents on the Cp ring are employed.28 Our experimental results
support these theoretical predictions.
In conclusion, the synthesis and characterization of cationic
titanium compounds derived from the reaction of monocyclo-
pentadienyl phenylenediamido alkyl titanium derivatives with
boron reagents are described. It has been demonstrated that the
existence or absence of anion coordination is a reflection of
the solvent polarity used for the reaction. Depending on the
nature of the cyclopentadienyl ligand, the cationic complexes
decompose, in solution, through different pathways, reflecting
the decisive role of the cyclopentadienyl ring in determining
the way that the cations evolve. The solution chemistry, solid
state structure, and polymerization behavior are self-consistent
and afford considerable insight into the nature of potentially
active species in the olefin polymerization reactions.
{TiCp[1,2-C6H4(NNp)2](solvent)n}+[CH3B(C6F5)3]- (6a). A
mixture of the methyl complex 2a (0.010 g, 0.027 mmol) and
B(C6F5)3 (0.013 g, 0.027 mmol) was dissolved in CD2Cl2 at room
1
temperature in the drybox to give dark solution. H NMR (300
MHz, CD2Cl2, 25 °C): δ 7.60 (m, 2H, Ph), 7.40 (m, 2H, Ph), 6.60
(s, 5H, C5H5), 4.18 (d, J ) 13.5 Hz, 2H, CH2), 3.95 (d, J ) 13.5
Hz, 2H, CH2), 0.77 (s, 18H, t-Bu), 0.41 (br, 3H, BCH3). 19F NMR
(282 MHz, CD2Cl2, 25 °C): δ -134.5 (br, o-C6F5), -161.1 (br,
p-C6F5), -164.2 (br, m-C6F5), ∆δ (p, m-F) ) 3.1 ppm.
Experimental Section
{TiCp[1,2-C6H4(NNp)2](solvent)n}+[PhCH2B(C6F5)3]- (6b).
Compound 6b was obtained in a manner similar to 4b using 0.010
g (0.022 mmol) and 0.011 g of B(C6F5)3 (0.022 mmol). The addition
General Considerations. All manipulations were performed
under rigorous exclusion of oxygen and moisture under argon using
Schlenk and high-vacuum line techniques or in a glovebox, model
MO40-2. Solvents were predried by standing over activated 4 Å
molecular sieves and then purified by distillation under argon before
use by employing the appropriate drying/deoxygenated agent.
Deuterated solvents were degassed by several freeze-thaw cycles
and stored in ampules equipped with Young’s Teflon valves over
activated 4 Å molecular sieves. C, H, and N microanalyses were
performed on a Perkin-Elmer 2400 microanalyzer. NMR spectra,
measured at 25 °C, were recorded on a Varian Unity FT-300 (1H
NMR at 300 MHz, 13C NMR at 75 MHz) spectrometer, and
chemical shifts were referenced to SiMe4 via the 13C resonances
and the residual protons (1H) of the deuterated solvent. LinBu (1.6
M in hexane solution) was purchased from Aldrich and Br(C6F5)
was purchased from ABCR. B(C6F5)3 and [Ph3C][B(C6F5)4] were
synthesized following established procedures.29-31 Alkyl compounds
TiCpR[1,2-C6H4(NCH2t-Bu)2]R (CpR ) η5-C5H5, η5-C5Me5, R )
Me, Bz) were prepared as described in previous work.5,6
TiCp[1,2-C6H4(NNp)2][µ-PhCH2B(C6F5)3] (4b). Compound 2b
(0.010 g, 0.022 mmol) and B(C6F5)3 (0.011 g, 0.022 mmol) were
loaded in a Teflon-valved NMR tube. C6D6 was charged, causing
the formation of a red solution. All operations described were
carried out in the drybox at room temperature. NMR data were
recorded at 25 °C. 1H NMR (300 MHz, C6D6, 25 °C): δ 7.38 (m,
2H, Ph), 6.97 (m, 2H, Ph), 6.18, 5.96, 5.87 (br, 5H, CH2Ph), 5.59
(s, 5H, C5H5), 4.04 (d, J ) 14.1 Hz, 2H, CH2), 3.75 (d, J ) 14.1
Hz, 2H, CH2), 2.87 (br, 2H, BCH2Ph), 0.42 (s, 18H, t-Bu). 13C-
{1H} NMR (75 MHz, C6D6, 25 °C): δ 159.6 (ipso-CH2Ph), 128.8,
119.9 (Ph), 131.6, 129.9, 128.8 (BCH2Ph), 118.2 (C5H5), 69.2
(CH2), 38.5 (BCH2Ph), 36.0 (ipso-t-Bu), 28.5 (t-Bu), 150.3, 147.2,
140.2, 139.1, 137.0, 135.6 (C6F5), Cipso for Ph group not observed.
19F NMR (282 MHz, C6D6, 25 °C): δ -131.1 (br, o-C6F5), -162.5
(br, p-C6F5), -166.0 (br, m-C6F5), ∆δ (p, m-F) ) 3.5 ppm.
TiCp*[1,2-C6H4(NNp)2][µ-CH3B(C6F5)3] (5a). C6D6 was added
to a mixture of 3a (0.010 g, 0.022 mmol) and B(C6F5)3 (0.011 g,
1
of CDCl3 produces a dark solution. H NMR (300 MHz, CDCl3,
25 °C): δ 7.66 (m, 2H, Ph), 7.36 (m, 2H, Ph), 6.88-6.78 (br, 5H,
CH2Ph), 6.25 (s, 5H, C5H5), 4.30 (d, J ) 13.8 Hz, 2H, CH2), 4.04
(d, J ) 13.8 Hz, 2H, CH2), 2.89 (br, 2H, CH2Ph), 0.67 (s, 18H,
t-Bu). 13C{1H} NMR (75 MHz, CDCl3, 25 °C): δ 148.6 (ipso-
CH2Ph), 126.7, 119.4 (Ph), 129.2-128.5 (BCH2Ph), 118.1 (C5H5),
69.3 (CH2), 38.0 (BCH2Ph), 36.0 (ipso-t-Bu), 28.5 (t-Bu), 149.7,
146.4, 139.0, 137.7, 135.7, 134.7 (C6F5), Cipso for Ph group not
observed. 19F NMR (282 MHz, CDCl3, 25 °C): δ -131.2 (m,
o-C6F5), -164.5 (m, p-C6F5), -167.2 (m, m-C6F5), ∆δ (p, m-F)
) 2.7 ppm.
{TiCp*[1,2-C6H4(NNp)2](solvent)n}+[CH3B(C6F5)3]- (7a). C6D6
was added to a mixture of 0.010 g (0.022 mmol) of 3a and 0.011
g (0.022 mmol) of B(C6F5)3 in a Young tube; an oily product was
precipitated. After 12 h the solvent was removed by decantation,
the residue was dried in vacuo, and CD2Cl2 was added to give a
dark red solution. All operations were performed in the drybox.
1H NMR (300 MHz, CD2Cl2, 25 °C): δ 7.62 (m, 2H, Ph), 7.56
(m, 2H, Ph), 4.59 (d, J ) 14.1 Hz, 2H, CH2), 4.09 (d, J ) 14.1
Hz, 2H, CH2), 2.17 (s, 15H, C5Me5), 0.77 (s, 18H, t-Bu), 0.50 (br,
3H, BCH3). 19F NMR (282 MHz, CD2Cl2, 25 °C): δ -131.5 (br,
o-C6F5), -163.7 (br, p-C6F5), -166.2 (br, m-C6F5), ∆δ (p, m-F) )
2.5 ppm.
{TiCp*[1,2-C6H4(NNp)2](solvent)n}+[PhCH2B(C6F5)3]- (7b).
C6D6 was added to a mixture of 0.010 g (0.019 mmol) of 3b and
0.010 g (0.019 mmol) of B(C6F5)3 in a Young tube, and an oily
product was precipitated. After 10 h the solvent was removed by
decantation, the residue was dried in vacuo, and CD2Cl2 was added
to give a dark red solution. All operations were performed in the
drybox. 1H NMR (300 MHz, CD2Cl2, 25 °C): δ 7.62 (m, 2H, Ph),
7.56 (m, 2H, Ph), 4.59 (d, J ) 14.4 Hz, 2H, CH2), 4.09 (d, J )
14.4 Hz, 2H, CH2), 2.81 (br, 2H, BCH2Ph), 2.17 (s, 15H, C5Me5),
0.77 (s, 18H, t-Bu). 19F NMR (282 MHz, CD2Cl2, 25 °C): δ -131.5
(br, o-C6F5), -163.7 (br, p-C6F5), -166.2 (br, m-C6F5), ∆δ (p, m-F)-
) 2.5 ppm.
(28) Wondimagegn, T.; Xu, Z. T.; Vanka, K.; Ziegler, T. Organometallics
TiCp[1,2-C6H4(NNp)2](C6F5) (8). LiB(C6F5) was prepared in
situ by the usual procedure, allowing 0.11 mL (0.867 mmol) of
Br(C6F5) and 0.54 mL (0.87 mmol) of LinBu to react in hexane at
-78 °C. Then 0.34 g (0.87 mmol) of 1a was added dropwise to
the stirring reaction mixture, which was maintained at low
temperature. After the addition was completed, the reaction mixture
2004, 23, 3847-3852.
(29) Massey, A. G.; Park, A. J. J. Organomet. Chem. 1964, 2, 461-
465.
(30) Massey, A. G.; Park, A. J. J. Organomet. Chem. 1964, 2, 245-
250.
(31) Massey, A. G.; Park, A. J. J. Organomet. Chem. 1966, 5, 218-
225.

Cationic Cyclopentadienyl Phenylenediamino Ti Species
Organometallics, Vol. 25, No. 7, 2006 1727
was warmed to room temperature and stirred for 12 h. The white
precipitate formed was filtered, and the resulting solution was cooled
to -40 °C. Compound 8 was obtained as a red oil in good yield,
60% (0.27 g, 0.52 mmol). Anal. Calcd for C27H31N2TiF5 (526.43
g/mol): C, 61.60; H, 5.94; N, 5.32. Found: C, 59.90; H, 6.04; N,
4.98. 1H NMR (300 MHz, C6D6, 25 °C): δ 7.09 (m, 2H, Ph), 7.00
(m, 2H, Ph), 6.22 (s, 5H, C5H5), 4.14 (d, J ) 13.5 Hz, 2H, CH2),
Mo KR, λ ) 0.71073 Å, ω-scan, diffractometer Siemens Smart
APEX CCD, T ) 100(2) K, 30 724 reflections were collected, of
which 10 308 were independent (Rint ) 0.018), absorption correction
based on multiscans, Tmin/Tmax 0.887/0.949, direct primary solution
and refinement on F2 (SHELXS-97 and SHELXL-97, G. M.
Sheldrick, University of Go¨ttingen, 1997), 600 refined parameters,
hydrogen atoms refined as free for the mehtyl borate, rigid for the
rest of the methyl groups, and riding for any other hydrogen atom,
R1[I > 2σ(I)] ) 0.0363, wR2(all data) ) 0.097.
1
3.99 (d, J ) 13.5 Hz, 2H, CH2), 0.64 (s, 18H, t-Bu). H NMR
(300 MHz, CD2Cl2, 25 °C): δ 7.34 (m, 2H, Ph), 7.23 (m, 2H, Ph),
6.51 (s, 5H, C5H5), 4.39 (d, J ) 13.5 Hz, 2H, CH2), 4.19 (d, J )
13.5 Hz, 2H, CH2), 0.78 (s, 18H, t-Bu). 13C{1H} NMR (75 MHz,
C6D6, 25 °C): δ 127.5, 120.4 (Ph), 114.8 (C5H5), 67.1 (CH2), 35.6
(ipso-t-Bu), 28.7 (t-Bu), Cipso for Ph not observed. 19F NMR (282
MHz, C6D6, 25 °C): δ -119.1 (br, o-C6F5), -158.5 (br, p-C6F5),
-162.7 (br, m-C6F5). 19F NMR (282 MHz, CD2Cl2, 25 °C): δ
-119.9 (br, o-C6F5), -160.2 (br, p-C6F5), -164.0 (br, m-C6F5).
X-ray data for compound 5a: dark red prism, 0.49 × 0.23 ×
0.17 mm size, triclinic, P1h, a ) 11.1096(4) Å, b ) 12.2344(4) Å,
c ) 17.8694(6) Å, R ) 86.356(1)°, â ) 75.321(1)°, γ ) 63.958-
(1)°, V ) 2107.8(1) Å3, Z ) 2, Fcalcd ) 1.507 g cm-3, θmax ) 28.05,
Acknowledgment. Financial support for this research by
DGICYT (Project MAT2004-02614) and C.A.M. (Project GR/
MAT/0622/2004) is gratefully acknowledged. M.C.M. acknowl-
edges Universidad de Alcala´ for a fellowship.
Supporting Information Available: Crystallographic data for
5a in CIF format. This material is available free of charge via the
Internet at http://pubs.acs.org.
OM051088Y