New titanium complexes containing a cyclopentadienyl ligand with a pendant aminoalkyl substituent: Preparation, behavior of the amino group, and catalytic hydroamination of alkynes

Article abstract of DOI:10.1021/om050542v

Complex Cp^NTiCl₃ (1) (Cp^N = C ₅H₄CH₂CH₂NMe₂) reacts with 1.0, 2.0, and 3.0 equiv of MeMgCl to give Cp^NTiMeCl₂ (2), Cp^NTiMe₂Cl (3), and Cp^NTiMe₃ (4), respectively. In the solid state, the amino group of the pendant substituent of the cyclopentadienyl ligand is weakly coordinated to the metal center (d(Ti - N) = 2.445(2) A in 2 and 2.433(4) A in 3), transoid disposed to a methyl ligand. In solution, the N-donor substituent is involved in a coordination-dissociation equilibrium (ΔH° = 2.4 ± 0.3 kcal·mol^-1 and ΔS° = 6.5 ± 0.9 cal·mol^-1·K^-1 for 2, ΔH° = 3.8 ± 0.4 kcal·mol^-1 and ΔS° = 12.3 ± 1.0 cal·mol^-1·K^-1 for 3, and ΔH° = 4.4 ± 0.1 kcal·mol^-1 and ΔS° = 17.9 ± 0.4 cal·mol^-1·K^-1 for 4). In moist benzene, complex 3 affords the dinuclear species Cp^NTiCl(μ-O) ₂ClTiCp^N (5), containing a planar Ti₂-(μ-O) ₂ core. In the solid state, the pendant amino groups of 5 are also coordinated to the metal centers (d(Ti-N) = 2.421(2) A). Like in 2, 3, and 4, the amino groups of 5 are involved in a coordination-dissociation equilibrium (ΔH° = 4.9 ± 0.2 kcal·(mol of Ti) ^-1 and ΔS° = 20.7 ± 0.6 cal·K ^-1·(mol of Ti)^-1). Complex 1 also reacts with LiNH(2,6-ⁱPr₂C₆H₃). The reaction leads to the six-coordinate amido-imido derivative {(2,6-ⁱPr ₂C₆H₃)NH}Cp^NTi{N(2,6- ⁱPr₂C₆H₃)} (6), which shows a strong coordination of the pendant amino group to the titanium atom (d(Ti-N _amino) = 2.227(2) A). In solution the amino group remains coordinated. Complex 4 has been found to be an efficient catalyst precursor for the intermolecular regioselective anti-Markovnikov hydroamination of asymmetric alkynes. The reactions give enamineimine mixtures, which are transformed into the corresponding secondary amines.

Full text of DOI:10.1021/om050542v

5084
Organometallics 2005, 24, 5084-5094
New Titanium Complexes Containing a Cyclopentadienyl
Ligand with a Pendant Aminoalkyl Substituent:
Preparation, Behavior of the Amino Group, and
Catalytic Hydroamination of Alkynes
Miguel A. Esteruelas,* Ana M. Lo´pez, A. Concepcio´n Mateo, and Enrique On˜ate
Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received June 29, 2005
Complex CpNTiCl3 (1) (CpN ) C5H4CH2CH2NMe2) reacts with 1.0, 2.0, and 3.0 equiv of
MeMgCl to give CpNTiMeCl2 (2), CpNTiMe2Cl (3), and CpNTiMe3 (4), respectively. In the
solid state, the amino group of the pendant substituent of the cyclopentadienyl ligand is
weakly coordinated to the metal center (d(Ti-N) ) 2.445(2) Å in 2 and 2.433(4) Å in 3),
transoid disposed to a methyl ligand. In solution, the N-donor substituent is involved in a
coordination-dissociation equilibrium (∆H° ) 2.4 ( 0.3 kcal‚mol-1 and ∆S° ) 6.5 ( 0.9
cal‚mol-1‚K-1 for 2, ∆H° ) 3.8 ( 0.4 kcal‚mol-1 and ∆S° ) 12.3 ( 1.0 cal‚mol-1‚K-1 for 3,
and ∆H° ) 4.4 ( 0.1 kcal‚mol-1 and ∆S° ) 17.9 ( 0.4 cal‚mol-1‚K-1 for 4). In moist benzene,
complex 3 affords the dinuclear species CpNTiCl(µ-O)2ClTiCpN (5), containing a planar Ti2-
(µ-O)2 core. In the solid state, the pendant amino groups of 5 are also coordinated to the
metal centers (d(Ti-N) ) 2.421(2) Å). Like in 2, 3, and 4, the amino groups of 5 are involved
in a coordination-dissociation equilibrium (∆H° ) 4.9 ( 0.2 kcal‚(mol of Ti)-1 and ∆S° )
20.7 ( 0.6 cal‚K-1‚(mol of Ti)-1). Complex 1 also reacts with LiNH(2,6-iPr2C6H3). The reaction
leads to the six-coordinate amido-imido derivative {(2,6-iPr2C6H3)NH}CpNTi{N(2,6-iPr2C6H3)}
(6), which shows a strong coordination of the pendant amino group to the titanium atom
(d(Ti-Namino) ) 2.227(2) Å). In solution the amino group remains coordinated. Complex 4
has been found to be an efficient catalyst precursor for the intermolecular regioselective
anti-Markovnikov hydroamination of asymmetric alkynes. The reactions give enamine-
imine mixtures, which are transformed into the corresponding secondary amines.
Introduction
the study of some processes.5 As a consequence of this,
complexes containing cyclopentadienyl ligands with a
pendant donor substituent are attracting increased
interest from those who study the chemistry of metals.6
Our group also is actively interested in this type of
compounds, and recently we have studied the chemical
behavior of [2-(dimethylamino)ethyl]cyclopentadien-
yliridium7 and [2-(diphenylphosphino)ethyl]cyclopenta-
dienyl-,8 (2-methoxyethyl)cyclopentadienyl-,9 and [2-(di-
methylamino)ethyl]cyclopentadienylosmium deriva-
tives.9,10 Now we report on [2-(dimethylamino)ethyl]-
cyclopentadienyltitanium complexes.
For our objective of designing metallic homogeneous
systems that are effective in the synthesis of function-
alized organic molecules from basic hydrocarbon units,1
the cyclopentadienyl group is of particular interest. This
ligand occupies a face of the metal complex, while the
other one remains free for the entry of the organic
substrates.2
A modification is the use of a pendant donor substitu-
ent. Due to the reversible coordination of the pendant
group,3 cyclopentadienyl ligands with substituents of
this type can stabilize highly reactive centers until the
substrates coordinate and replace the pendant group.4
The stabilizing effect has a strong influence on the
catalytic properties of the active systems and facilitates
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* To whom correspondence should be addressed. E-mail: maester@
unizar.es.
(1) Esteruelas, M. A.; Lo´pez, A. M. In Recent Advances in Hydride
Chemistry; Peruzzini, M., Poli, R.; Eds.; Elsevier: Amsterdam, 2001;
Chapter 7, pp 189-248.
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10.1021/om050542v CCC: $30.25 © 2005 American Chemical Society
Publication on Web 09/13/2005

Ti Complexes Containing a Cyclopentadienyl Ligand
Organometallics, Vol. 24, No. 21, 2005 5085
The chemistry of ring-substituted monocyclopenta-
dienyl titanium(IV) compounds is an active field of
group 4 metal research.6f Compared to the systems with
constrained geometry, the monocyclopentadienyl tita-
nium derivatives containing a dialkylamino side group11
remain an underrepresented area within the group 4
metal complexes containing a cyclopentadienyl ligand
with a pendant group.6b-e As far as we know, only
trichloro derivatives have been reported.
Rausch and co-workers12 have described the prepara-
tion of the half-sandwich complex CpNTiCl3 (CpN
)
C5H4CH2CH2NMe2), which is an active precursor in
Ziegler-Natta polymerization catalysis.13 The amino
group affects significantly its catalytic reactivity as
compared to that of the parent complex CpTiCl3.14 The
system CpNTiCl3-MAO (MAO ) methylaluminoxane)
shows a considerably lower activity toward styrene and
an impressively increased activity toward ethylene and
propylene. This has been attributed to the coordination
behavior of the amino group, which influences the
coordination of the incoming monomer.13
Figure 1. Molecular diagram of CpNTiMeCl2 (2).
Scheme 1
Although the influence of the pendant group on the
catalytic activity of these systems is evident, studies on
its behavior in the solid state and in solution are very
scarce in the chemistry of group 4 metals.15 In this paper
we show the behavior of the pendant amine group of
the [2-(dimethylamino)ethyl]cyclopentadienyl ligand in
(i) the complexes resulting from the sequential methy-
lation of CpNTiCl3, (ii) the product from the hydrolysis
of CpNTiMe2Cl, and (iii) the amido-imido derivative
{(2,6-iPr2C6H3)NH}CpNTi{N(2,6-iPr2C6H3)}. In addition,
as a part of our effort to develop effective methods of
C-N bond formation,16 the catalytic activity of CpN-
TiMe3 in the hydroamination of alkynes is also re-
ported.17
Results and Discussion
In the solid state the dimethylamino group coordi-
nates to the metal center of 2. Figure 1 shows a view of
the structure of this compound. Selected bond distances
and angles are listed in Table 1.
1. CpNTiMexCl3-x (x ) 1-3) Complexes. The ad-
dition of 1.0 equiv of MeMgCl in tetrahydrofuran to a
suspension of CpNTiCl3 (1) in diethyl ether produces the
selective substitution of one of the chloride ligands of 1
by a methyl group and the formation of the monomethyl
derivative CpNTiMeCl2 (2), which is isolated as a brown
solid in 43% yield, according to Scheme 1.
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precursors in organic transformations. Among the various reasons to
employ this element is its inexpensive and ubiquitous availability as
compared to toxic or more expensive metals. See: (a) Petasis, N. A.;
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5086 Organometallics, Vol. 24, No. 21, 2005
Esteruelas et al.
Table 1. Selected Bond Distances (Å) and Angles
(deg) for Complex CpNTiMeCl2 (2)
Ti-Cl(1)
Ti-Cl(2)
Ti-C(1)
Ti-N(1)
Ti-C(4)
Ti-C(5)
Ti-C(6)
2.3004(8)
2.3091(8)
2.144(3)
2.445(2)
2.346(2)
2.342(3)
2.346(3)
Ti-C(7)
2.355(2)
2.343(3)
1.489(3)
1.482(3)
1.480(3)
1.518(4)
1.502(4)
Ti-C(8)
N(1)-C(2)
N(1)-C(9)
N(1)-C(10)
C(2)-C(3)
C(3)-C(4)
C(1)-Ti-Cl(1)
C(1)-Ti-Cl(2)
C(1)-Ti-N(1)
C(1)-Ti-Ma
85.10(9)
83.61(9)
N(1)-Ti-Ma
102.0
Ti-N(1)-C(2)
104.98(15)
115.03(17)
113.85(16)
107.8(2)
151.34(11) Ti-N(1)-C(9)
106.6
Ti-N(1)-C(10)
C(2)-N(1)-C(9)
Cl(1)-Ti-Cl(2) 125.18(3)
Cl(1)-Ti-N(1)
Cl(1)-Ti-Ma
Cl(2)-Ti-N(1)
Cl(2)-Ti-Ma
83.42(6)
115.3
81.77(5)
119.3
C(2)-N(1)-C(10) 108.5(2)
C(9)-N(1)-C(10) 106.5(2)
N(1)-C(2)-C(3)
C(2)-C(3)-C(4)
110.5(2)
110.2(2)
a M represents the midpoint of the C(4)-C(8) Cp ligand.
The distribution of ligands around the titanium atom
can be described as a four-legged piano stool geometry,
with the cyclopentadienyl ring occupying the three-
membered face, while the nitrogen atom of the pendant
group lies in the four-membered face transoid disposed
to the methyl ligand (C(1)-Ti-N(1) ) 151.34(11)°). The
Ti-N(1) and Ti-C(1) distances are 2.445(2) and
2.144(3) Å, respectively. In agreement with the sp3
hybridization at N(1), the angles around this atom are
between 104.98(15)° and 115.03(17)°.
Figure 2. Variable-temperature 1H NMR spectra for
complex CpNTiMeCl2 (2) (toluene-d8). *Denotes residual
solvent peak.
In solution, the pendant N-donor substituent of the
cyclopentadienyl ligand is involved in a coordination-
dissociation process (eq 1). This is strongly supported
by the 1H and 13C{1H} NMR spectra in toluene-d8,
which are temperature dependent. Figure 2 shows the
1H NMR spectrum as a function of the temperature. At
363 K, the spectrum contains two cyclopentadienyl
resonances at 6.40 and 5.99 ppm, a signal at 2.17 ppm
for the pendant chain protons, and singlets at 2.09
(NMe2) and 1.70 (TiMe) corresponding to the methyl
groups of the molecule. Lowering the sample tempera-
ture produces an increase of the separation between the
cyclopentadienyl resonances, which at 223 K appear at
6.34 and 5.68 ppm, whereas the signal due to the
pendant chain protons is converted into two resonances,
which are shifted toward higher field as the temperature
decreases. Thus, at 223 K, they are observed at 1.76
(NCH2) and 1.46 (CpCH2) ppm. The NMe2 resonance is
also shifted to higher field. At 223 K, it appears at 1.95
ppm. On the other hand, the TiMe resonance is shifted
toward lower field. At 223 K, it is observed at 1.83
ppm.
the procedure previously used by van der Zeijden and
co-workers,15a according to eq 2.18
δmin(CpCH2) - δ(CpCH2)
δ(CpCH2) - δmax(CpCH2)
[b]
[a]
K )
)
)
δmin(CH2N) - δ(CH2N)
δ(CH2N) - δmax(CH2N)
(2)
The temperature dependence of the equilibrium gives
the values ∆H° ) 2.4 ( 0.3 kcal‚mol-1 and ∆S° ) 6.5 (
0.9 cal‚mol-1‚K-1. The positive value of ∆S° is in
agreement with the free character of the dimethylamino
pendant group in 2b, whereas the low value of ∆H°
indicates a weak Ti-N bond.
Treatment of 1 with 2.0 equiv of MeMgCl produces
the substitution of two chloride ligands of the starting
compound by methyl groups and the formation of the
dimethyl derivative CpNTiMe2Cl (3), which is isolated
as a red solid in 50% yield (Scheme 1).
Like 2, complex 3 was characterized by X-ray diffrac-
tion analysis. The structure proves that in the solid state
the pendant dimethylamino group is also coordinated
to the metal center of 3. Figure 3 shows a view of the
structure of this compound. Selected bond distances and
angles are collected in Table 2.
The distribution of ligands around the titanium is like
that of 2, with the methyl groups mutually cisoid
disposed (C(1)-Ti-C(2) ) 81.7(2)°) and the pendant
For the process shown in eq 1, the equilibrium
constants between 363 and 223 K were determined by
(18) Dalling, D. K.; Zlim, K. W.; Grant, D. M.; Heeschen, W. A.;
Horton, W. J.; Pugmire, R. J. J. Am. Chem. Soc. 1981, 103, 4817.

Ti Complexes Containing a Cyclopentadienyl Ligand
Organometallics, Vol. 24, No. 21, 2005 5087
Figure 3. Molecular diagram of CpNTiMe2Cl (3).
Figure 4. Molecular diagram of CpNTiCl(µ-O)2ClTiCpN (5).
Table 2. Selected Bond Distances (Å) and Angles
(deg) for Complex CpNTiMe2Cl (3)
In solution, the behavior of the pendant amino group
of 4 is like that of 2 and 3. In accordance with this, the
1H and 13C{1H} NMR spectra of 4 are also temperature
dependent and completely analogous to those of 2 and
3. The values of parameters ∆H° and ∆S°, obtained from
the temperature dependence of the equilibrium, are 4.4
( 0.1 kcal‚mol-1 and 17.9 ( 0.4 cal‚mol-1‚K-1, respec-
tively.
The values obtained for ∆H° and ∆S° in the sequence
2-3-4 show that both ∆H° and ∆S° increase as the
chloride ligands at the titanium atom are replaced by
methyl groups. Accordingly, the molar fraction of hexa-
coordinate form b at 20 °C increases in the sequence 2
(0.30) < 3 (0.35) < 4 (0.82). This appears to be a
consequence of the steric hindrance experienced by the
dimethylamino group and the methyl ligands, when
they are mutually cisoid disposed.
Ti-Cl
2.3253(19)
2.150(5)
2.130(5)
2.433(4)
2.360(5)
2.356(5)
2.376(5)
Ti-C(6)
Ti-C(7)
N-C(9)
N-C(10)
N-C(11)
C(3)-C(8)
C(8)-C(9)
2.376(5)
2.355(5)
1.500(6)
1.479(6)
1.484(6)
1.473(6)
1.520(7)
Ti-C(1)
Ti-C(2)
Ti-N
Ti-C(3)
Ti-C(4)
Ti-C(5)
C(1)-Ti-Cl
C(1)-Ti-C(2)
C(1)-Ti-N
C(1)-Ti-Ma
Cl-Ti-C(2)
Cl-Ti-N
84.59(15)
81.7(2)
150.11(18)
107.4
123.30(14)
81.89(11)
125.4
83.69(17)
111.2
N-Ti-Ma
Ti-N-C(9)
102.2
106.3(3)
114.2(3)
113.3(3)
107.5(4)
107.5(4)
107.7(4)
110.2(4)
110.6(4)
Ti-N-C(10)
Ti-N-C(11)
C(9)-N-C(10)
C(9)-N-C(11)
C(10)-N-C(11)
N-C(9)-C(8)
C(9)-C(8)-C(3)
Cl-Ti-Ma
C(2)-Ti-N
C(2)-Ti-Ma
a M represents the midpoint of the C(3)-C(7) Cp ligand.
dimethylamino group transoid disposed to C(1) (C(1)-
Ti-N ) 150.11(18)°). The Ti-N bond length of 2.433-
(4) Å is statistically identical with the related parameter
in 2, and both distances compare well with the Ti-N
bond lengths found in complexes containing dative
nitrogen-titanium bonds.11b,c The angles around the
nitrogen atom are between 106.3(3)° and 114.2(3)°. The
Ti-C(1) (2.150(5) Å) and Ti-C(2) (2.130(5) Å) distances
are also statistically identical with the titanium-methyl
separation in 2. However, the Ti-Cl bond length
(2.3253(19) Å) is slightly longer than the Ti-Cl dis-
tances in the monomethyl derivative (2.3004(8) and
2.3091(8) Å).
2. CpNTiCl(µ-O)2ClTiCpN. The dimethyl complex 3
in moist benzene or toluene is transformed to the dimer
derivative CpNTiCl(µ-O)2ClTiCpN (5), as a result of the
hydrolysis of the Ti-C bonds (eq 3). We note that the
trimethyl complex (η5-C5Me5)TiMe3 undergoes hydroly-
sis to give first [(η5-C5Me5)TiMe2]2(µ-O) and then [(η5-
C5Me5)TiMe(µ-O)]3, which has been characterized by
X-ray diffraction analysis.19
In solution, the pendant N-donor substituent of the
cyclopentadienyl ligand of 3 is also involved in a
coordination-dissociation process like that shown in eq
1
1. In agreement with this, the behavior of the H and
A few crystals of 5 suitable for an X-ray diffraction
study were obtained in an NMR tube, from a toluene-
d8 solution of this compound. Figure 4 shows a view of
its structure. Selected bond distances and angles are
collected in Table 3.
Complex 5 can be described as a dinuclear species
containing a planar Ti2(µ-O)2 core with Ti-O distances
of 1.7980(17) (Ti(1)-O(1)) and 1.9271(16) (Ti(1)-O(1A))
Å and with angles of 82.29(7)° at the titanium atom and
97.71(7)° at the oxygen atom. These structural param-
13C{1H} NMR spectra of 3 with the temperature is
similar to that described for 2. In this case, the tem-
perature dependence of the equilibrium gives the values
∆H° ) 3.8 ( 0.4 kcal‚mol-1 and ∆S° ) 12.3 ( 1.0
cal‚mol-1‚K-1, which are slightly higher than those
obtained for 2.
The addition of 3.0 equiv of MeMgCl to a diethyl ether
suspension of 1 produces the substitution of the three
chloride ligands of the starting complex by methyl
groups. As a result, the trimethyl derivative CpNTiMe3
(4) is formed, according to Scheme 1. Complex 4 is
isolated as an orange oil in 55% yield.
(19) Garc´ıa-Blanco, S.; Go´mez-Sal, M. P.; Mart´ınez-Carreras, S.;
Mena, M.; Royo, P.; Serrano, R. J. Chem. Soc., Chem. Commun. 1986,
1572.

5088 Organometallics, Vol. 24, No. 21, 2005
Esteruelas et al.
Table 3. Selected Bond Distances (Å) and Angles
(CH2Cp), 2.05 (CH2N), and 1.87 (CH3) ppm. In this case,
the values of parameters ∆H° and ∆S° for the coordina-
tion-dissociation equilibrium process are 4.9 ( 0.2 kcal‚
(deg) for Complex CpNTiCl(µ-O)2ClTiCpN (5)
Ti(1)-Cl(1)
Ti(1)-O(1)
Ti(1)-O(1A)
Ti(1)-N(1)
Ti(1)-C(1)
Ti(1)-C(2)
Ti(1)-C(3)
2.3579(8)
1.7980(17)
1.9271(16)
2.421(2)
Ti(1)-C(4)
Ti(1)-C(5)
N(1)-C(7)
N(1)-C(8)
N(1)-C(9)
C(1)-C(6)
C(6)-C(7)
2.414(2)
2.424(2)
1.480(3)
1.476(3)
1.483(3)
1.503(3)
1.532(3)
(mol of Ti)-1 and 20.7 ( 0.6 cal‚K-1‚(mol of Ti)-1
,
respectively, whereas in toluene at 20 °C the molar
fraction of six-coordinate titanium atoms is 0.88.
2.396(2)
3. {(2,6-iPr2C6H3)NH}CpNTi{N(2,6-iPr2C6H3)}. The
hydroamination of alkenes and alkynes constitutes an
atom economical method for the synthesis of nitrogen-
containing molecules from inexpensive starting
materials.17b,d,e,g;26 Among the catalysts used in these
reactions, titanium metallocene derivatives occupy a
prominent place.27 Kinetic studies have revealed a
cyclopentadienyl-amide ligand exchange reaction that
transforms the titanium metallocene precursor into a
monocyclopentadienyl-amido-imido derivative.28 A spe-
cies of this type containing the [2-(dimethylamino)ethyl]-
cyclopentadienyl ligand can be easily prepared starting
from 1. Treatment of a diethyl ether suspension of the
latter with 3.3 equiv of LiNH(2,6-iPr2C6H3) affords the
amido-imido complex {(2,6-iPr2C6H3)NH}CpNTi{N(2,6-
iPr2C6H3)} (6), which is isolated as a yellow solid in 42%
yield, according to eq 4.
2.351(2)
2.369(2)
O(1)-Ti(1)-O(1A)
O(1)-Ti(1)-Cl(1)
O(1)-Ti(1)-N(1)
O(1)-Ti(1)-Ma
82.29(7) Ti(1)-O(1)-Ti(1A)
120.11(5) Ti(1)-N(1)-C(7)
80.48(7) Ti(1)-N(1)-C(8)
97.71(7)
105.03(14)
109.28(14)
118.27(14)
108.01(18)
106.91(19)
109.00(19)
110.81(19)
109.5(2)
119.7
Ti(1)-N(1)-C(9)
O(1A)-Ti(1)-Cl(1)
87.39(5) C(7)-N(1)-C(8)
O(1A)-Ti(1)-N(1) 150.77(7) C(8)-N(1)-C(9)
Cl(1)-Ti(1)-N(1)
Cl(1)-Ti(1)-Ma
N(1)-Ti(1)-Ma
81.12(5) C(7)-N(1)-C(9)
119.4
99.7
N(1)-C(7)-C(6)
C(7)-C(6)-C(1)
a M represents the midpoint of the C(1)-C(5) Cp ligand.
eters agree well with those recently reported for the
complexes Ti2(O2tBuNN′)2(µ-O)2 (O2tBuNN′ ) (2-C5H4N)-
t
CH2N(2-O-3,5-C6H2 Bu2)2)20a and trans-[Ti2(η5-C5H4-
Me)2(µ-O)2{Me3SiNC(Ph)N(CH2)nNMe2}2] (n ) 2, 3).20b
The separation between the titanium atoms of
2.8064(9) Å is comparable with those of other known
examples with a planar Ti2(µ-O)2, i.e., [Ti(acac)2(µ-O)]2
(2.729(1) Å),21 K4[Ti(O2C6H4)2(µ-O)]2‚9H2O (2.819(1)
Å),22 [(η5:η1-C5H4CMe2C6H4N)TiCl]2(µ-O)2 (2.801(1) Å),23
[{η5-C5H2(Me3Si)3}TiCl]2(µ-O)2 (2.707(0) Å),24 and
[(η5-C5Me5)Ti(µ-O)(CMePy2)]2 (2.863(4) Å).25
Like in the mononuclear complexes 2 and 3, the
pendant dimethylamino groups are coordinated to the
metal centers. Thus, the distribution of ligands around
each titanium atom can be described as a four-legged
piano stool geometry, with the nitrogen atom of the
pendant group and the chloride ligand in the four-
membered face, transoid disposed to the oxygen atoms
of the Ti2(µ-O)2 core (O(1A)-Ti(1)-N(1) ) 150.77(7)°
and O(1)-Ti-Cl(1) ) 120.11(5)°). The Ti-N bond
lengths of 2.421(2) Å are about 0.02 Å shorter than the
Ti-N distance in 2 and about 0.01 Å shorter than that
in 3. However, the Ti-Cl bond lengths of 2.3579(8) Å
are between 0.04 and 0.05 Å longer than the Ti-Cl
distances in 2 and about 0.03 Å longer than that in 3.
A view of the molecular geometry of 6 is shown in
Figure 5. Selected bond distances and angles are listed
in Table 4. The geometry around the titanium center
can be described as a very distorted octahedron, with
the cyclopentadienyl group occupying a face. The distor-
tion is revealed by the N(1)-Ti-N(2) (101.82(11)°),
N(1)-Ti-N(3)
(94.98(10)°),
and
N(2)-Ti-N(3)
(109.20(10)°) angles, which strongly deviate from the
ideal value of 90°, and it appears to be a consequence
of both the constriction imposed by the CH2-CH2 string
in the [2-(dimethylamino)ethyl]cyclopentadienyl ligand
and the steric hindrance experienced by the isopropyl
substituents of the phenyl groups of the mutually cis-
disposed imido and amido ligands.
The N(2,6-iPr2C6H3) group acts as a 4e- donor ligand.
This is supported by the Ti-N(1) bond length of
1.742(2) Å, which compares well with those found in
1
The H and 13C{1H} NMR spectra of 5 in toluene-d8
are similar to those of 2-4. Their behavior with the
temperature, like that of the mononuclear species, is
consistent with a rapid coordination-dissociation equi-
librium process of the nitrogen atom of the pendant
substituent of the cyclopentadienyl ligand. Thus, at 333
1
K, the H NMR spectrum shows two cyclopentadienyl
resonances at 6.08 and 6.04 ppm, two CH2 resonances
at 2.60 and 2.44 ppm, and a methyl resonance at 2.13
ppm, while at 233 K, the resonances corresponding to
the same protons appear at 6.08 and 5.89 (Cp), 2.40
(26) Beller, M.; Seayad, J.; Tillack, A.; Jiao, H. Angew. Chem. Int.
Ed. 2004, 43, 3368.
(27) See for example: (a) Haak, E.; Bytschkov, I.; Doye, S. Angew.
Chem. Int. Ed. 1999, 38, 3389. (b) Haak, E.; Siebeneicher, H.; Doye,
S. Org. Lett. 2000, 2, 1935. (c) Bytschkov, I.; Doye, S. Eur. J. Org.
Chem. 2001, 4411. (d) Tillack, A.; Garcia Castro, I.; Hartung, C. G.;
Beller, M. Angew. Chem. Int. Ed. 2002, 41, 2541. (e) Heutling, A.; Doye,
S. J. Org. Chem. 2002, 67, 1961. (f) Siebeneicher, H.; Doye, S. Eur. J.
Org. Chem. 2002, 1213. (g) Garcia Castro, I.; Tillack, A.; Hartung, C.
G.; Beller, M. Tetrahedron Lett. 2003, 44, 3217. (h) Bytschkov, I.;
Siebeneicher, H.; Doye, S. Eur. J. Org. Chem. 2003, 2888. (i) Pohlki,
F.; Bytschkov, I.; Siebeneicher, H.; Heutling, A.; Ko¨nig, W. A.; Doye,
S. Eur. J. Org. Chem. 2004, 1967. (j) Heutling, A.; Ko¨ning, W. A.; Doye,
S. Chem. Eur. J. 2004, 10, 3059.
(20) (a) Boyd, C. L.; Toupance, T.; Tyrrel, B. R.; Ward, B. D.; Wilson,
C. R.; Cowley, A. R.; Mountford, P. Organometallics 2005, 24, 309. (b)
Boyd, C. L.; Clot, E.; Guiducci, A. E.; Mountford, P. Organometallics
2005, 24, 2347.
(21) Smith, G. D.; Caughlan, C. N.; Campbell, J. A. Inorg. Chem.
1972, 11, 2989.
(22) Borgias, B. A.; Cooper, S. R.; Koh, Y. B.; Raymond, K. N. Inorg.
Chem. 1984, 23, 1009.
(23) Clark, T. J.; Nile, T. A.; McPhail, D.; McPhail, A. T. Polyhedron
1989, 8, 1804.
(24) Okuda, J.; Herdtweck, E. Inorg. Chem. 1991, 30, 1516.
(25) Fandos, R.; Herna´ndez, C.; Otero, A.; Rodr´ıguez, A.; Ruiz, M.
J.; Terreros, P. J. Chem. Soc., Dalton Trans. 2002, 11.
(28) (a) Johnson, J. S.; Bergman, R. G. J. Am. Chem. Soc. 2001,
123, 2923. (b) Pohlki, F.; Doye, S. Angew. Chem. Int. Ed. 2001, 40,
2305.

Ti Complexes Containing a Cyclopentadienyl Ligand
Organometallics, Vol. 24, No. 21, 2005 5089
tion at N(2) (Ti-N(2)-C(13) ) 137.0(2)°) with the out-
plane lone pair giving a N(pπ)fM(dπ) interaction. Thus,
the NH(2,6-iPr2C6H3) group should be considered a 3e-
donor ligand. Interestingly, the Ti-N(3) bond length of
2.227(2) Å is about 0.2 Å shorter than the Ti-amino
separation in 2, 3, and 5. This suggests that the
coordination of the pendant amino group to the titanium
center is much stronger in 6 than in 2, 3, and 5, which
could be related to the fact that 6 possesses one ligand
less than 2, 3, and 5.
The 1H and 13C{1H} NMR spectra of 6 reveal that, in
contrast to 2-5, the pendant amino group of the
[2-(dimethylamino)ethyl]cyclopentadienyl ligand does
not dissociate in solution, in agreement with the ex-
pected high stability of the Ti-N(3) bond. Thus, both
1
the H and 13C{1H} NMR spectra are consistent with
the structure shown in Figure 5. Due to the chirality of
the titanium atom, the 1H spectrum in toluene-d8, which
is temperature invariant between 333 and 213 K, shows
an ABCD spin system for the methylene resonances. It
appears between 2.50 and 1.97 ppm, whereas the
resonances corresponding to the cyclopentadienyl pro-
tons, which also display an ABCD spin system, are
observed between 6.38 and 5.48 ppm. The spectrum also
contains two singlets at 2.26 and 2.25 ppm due to the
dimethylamino group. In the 13C{1H} NMR spectrum
the most noticeable resonances are those due to the
cyclopentadienyl ring, which appear at 131.0, 115.4,
108.3, 106.6, and 106.0 ppm, and two singlets at 50.1
and 49.3 ppm corresponding to the dimethylamino
group.
4. Hydroamination of Alkynes Catalyzed by
CpNTiMe3. Mechanistic studies suggest that the key
step for the CpTi-catalyzed intermolecular hydro-
amination of alkynes is a reversible [2+2] cycloaddition
between the alkyne and the imido group of the unsatur-
ated amido-imido (RNH)CpTi(NR) catalyst.28 Complex
6 is also an amido-imido species. However, it is satu-
rated as a consequence of the coordination of the
pendant amino group, and in agreement with the high
stability of the titanium-amino bond, it is catalytically
inactive for the hydroamination of phenylacetylene,
1-phenylpropyne, and diphenylacetylene with 2,6-diiso-
propylaniline.
In contrast to 6, the trimethyl derivative 4 is a very
efficient catalyst precursor for the regioselective anti-
Markonikov hydroamination of phenylacetylene and
1-phenylpropyne, and the hydroamination of diphenyl-
acetylene with amines such as cyclohexylamine, 2,6-
dimethylaniline, tert-butylamine, and 2,6-diisopropyl-
aniline. The reactions were performed in toluene at 100
°C using 5 mol % of complex 4. Under these conditions
the alkynes react with the amines to afford the corre-
sponding enamine-imine mixtures, which were trans-
formed in quantitative yield into the secondary amines,
by reduction with molecular hydrogen in the presence
of PtO2 (eq 5).
Figure 5. Molecular diagram of {(2,6-iPr2C6H3)NH}CpN-
Ti{N(2,6-iPr2C6H3)} (6).
Table 4. Selected Bond Distances (Å) and Angles
(deg) for Complex
{(2,6-iPr2C6H3)NH}CpNTi{N(2,6-iPr2C6H3)} (6)
Ti-N(1)
Ti-N(2)
Ti-N(3)
Ti-C(25)
Ti-C(26)
Ti-C(27)
Ti-C(28)
Ti-C(29)
1.742(2)
1.939(2)
2.227(2)
2.395(3)
2.448(3)
2.418(3)
2.371(3)
2.365(3)
N(1)-C(1)
1.383(3)
1.433(3)
1.486(3)
1.481(3)
1.485(3)
1.508(4)
1.530(4)
N(2)-C(13)
N(3)-C(31)
N(3)-C(32)
N(3)-C(33)
C(25)-C(30)
C(30)-C(31)
N(1)-Ti-N(2)
N(1)-Ti-N(3)
N(1)-Ti-Ma
N(2)-Ti-N(3)
N(2)-Ti-Ma
N(3)-Ti-Ma
Ti-N(1)-C(1)
101.82(11) Ti-N(3)-C(31)
94.98(10) Ti-N(3)-C(32)
112.99(17)
109.82(17)
109.01(17)
108.7(2)
131.0
Ti-N(3)-C(33)
109.20(10) C(31)-N(3)-C(32)
113.5
C(31)-N(3)-C(33)
C(32)-N(3)-C(33)
N(3)-C(31)-C(30)
109.0(2)
103.6
107.1(2)
110.6(3)
174.7(2)
Ti-N(2)-C(13) 137.0(2)
C(25)-C(30)-C(31) 109.5(3)
a M represents the midpoint of the C(25)-C(29) Cp ligand.
other titanium-imido complexes.29 In agreement with
an sp hybridization at N(1), the coordination of the
imido is approximately linear with a Ti-N(1)-C(1)
angle of 174.7(2)°. The Ti-N(2) distance of 1.939(2) Å
is within the expected range for a titanium-amido
compound,30 and it is consistent with the planar geom-
etry of the nitrogen atom. This indicates sp2 hybridiza-
(29) (a) Roesky, H. W.; Voelker, H.; Witt, M.; Noltemeyer, M. Angew.
Chem., Int. Ed. Engl. 1990, 29, 669. (b) Doxsee, K. M.; Garner, L. C.;
Juliette, J. J. J.; Mouser, J. K. M.; Weakley, T. J. R.; Hope, H.
Tetrahedron 1995, 51, 4321. (c) Blake, A. J.; Collier, P. E.; Gade, L.
H.; McPartlin, M.; Mountford, P.; Schubart, M.; Scowen, I. J. Chem.
Commun. 1997, 1555. (d) Dunn, S. C.; Mountford, P.; Robson, D. A. J.
Chem. Soc., Dalton Trans. 1997, 293. (e) Stewart, P. J.; Blake, A. J.;
Mountford, P. Organometallics 1998, 17, 3271. (f) Wessel, H.; Montero,
M. L.; Rennekamp, C.; Roesky, H. W.; Yu, P.; Uso´n, I. Angew. Chem.
Int. Ed. 1998, 37, 843. (g) Jagirdar, B. R.; Murugavel, R.; Schmidt,
H.-G. Inorg. Chim. Acta 1999, 292, 105. (h) Guiducci, A. E.; Cowley,
A. R.; Skinner, M. E. G.; Mountford, P. J. Chem. Soc., Dalton Trans.
2001, 1392. (i) Li, Y.; Shi, Y.; Odom, A. L. J. Am. Chem. Soc. 2004,
126, 1794.
(30) See for example: (a) Giolando, D. M.; Kirchbaum, K.; Graves,
L. J.; Bolle, U. Inorg. Chem. 1992, 31, 3887. (b) Mart´ın, A.; Mena, M.;
Ye´lamos, C.; Serrano, R.; Raithby, P. R. J. Organomet. Chem. 1994,
467, 79. (c) Pupi, R. M.; Coalter, J. N.; Petersen, J. L. J. Organomet.
Chem. 1995, 497, 17. (d) Sinnema, P.-J.; van der Veen, L.; Spek, A. L.;
Veldman, N.; Teuben, J. H. Organometallics 1997, 16, 4245. (e)
Hughes, A. K.; Marsh, S. M. B.; Howard, J. A. K.; Ford, P. S. J.
Organomet. Chem. 1997, 528, 195. (f) Firth, A. V.; Stephan, D. W.
Inorg. Chem. 1998, 37, 4732. (g) Polse, J. L.; Andersen, R. A.; Bergman,
R. G. J. Am. Chem. Soc. 1998, 120, 13405. (h) Amor, F.; Go´mez-Sal,
P.; Royo, P.; Okuda, J. Organometallics 2000, 19, 5168.

5090 Organometallics, Vol. 24, No. 21, 2005
Esteruelas et al.
Table 5. CpNTiMe3-Catalyzed Hydroamination of
Alkynesa
phenylacetylene with 2,6-diisopropylaniline is faster
than with tert-butylamine (entries 11 and 12).
The results shown in Table 5 also indicate that, in
general, the hydroamination is favored with the increase
of the bulkiness of the substituent R′ of the alkyne
(H < Me < Ph), when the sterically less demanding
amines cyclohexylamine and 2,6-dimethylaniline are
used.
From the mechanistic point of view, it should be
mentioned that in the absence of alkyne the catalyst
precursor complex 4 reacts with 2,6-diisopropylaniline
to give 6. Because complex 6 is catalytically inactive,
its formation under these conditions suggests that the
alkyne plays a main role in the generation process of
the catalytically active species. Furthermore, since the
stability of the bond between the metal center and the
pendant amino group is higher for six-coordinate de-
rivatives than for seven-coordinate compounds, and the
dissociation of the pendant amino group is necessary
for the hydroamination reaction, it appears reasonable
to think that the catalytically active species, in this type
of system, is a six-coordinate complex containing a
dissociated pendant amino group.
Concluding Remarks
As a result of the extension of our work on the
chemistry of complexes containing cyclopentadienyl
ligands with a pendant donor substituent on the group
4 metals, in addition to gaining new information about
the behavior of the dimethylamino group of the [2-(di-
methylamino)ethyl]cyclopentadienyl ligand, we have
prepared new titanium complexes and have discovered
a new catalytic system.
a Reaction conditions: alkyne (2.40 mmol), amine (2.64 mmol),
octane (2.40 mmol), CpNTiMe3 (0.12 mmol, 5 mol %), toluene (2.0
mL), 100 °C. b Determined by GC. c Determined by 1H NMR
spectroscopy at the end of the reaction.
The reactions of complex CpNTiCl3 with 1.0, 2.0, and
3.0 equiv of MeMgCl afford the mono-, di-, and trimethyl
derivatives CpNTiMeCl2, CpNTiMe2Cl, and CpNTiMe3,
respectively. In the solid state, the aminoalkyl substitu-
ent of the cyclopentadienyl ligand of these compounds
is weakly bonded to the metal center, transoid disposed
to a methyl ligand. In solution, the amine dissociates
and an equilibrium between seven-coordinate and six-
coordinate species is reached. The molar fraction of
dissociated amine increases as the number of methyl
ligands at the titanium atom also increases. In moist
benzene or toluene, the Ti-C bonds of CpNTiMe2Cl
undergo hydrolysis to give CpNTiCl(µ-O)2ClTiCpN, which
can be described as a dinuclear species containing a
planar Ti(µ-O)2Ti core. The amino groups of this com-
pound show a behavior similar to the mononuclear
methyl complexes.
The hydroamination products are obtained in high
yield, with extremely high regioselectivity (Table 5).
After 8 h the amount of alkyne transformed into
hydroamination products mainly depends on the nature
of the amine. For the three alkynes, the hydroamination
with 2,6-dimethylaniline is favored with regard to that
with 2,6-diisopropylaniline (entries 2 and 4, 6 and 8,
and 10 and 12). However, for the cyclohexylamine-tert-
butylamine pair, the steric requirement of the alkyl
group appears to favor the N-H addition to the carbon-
carbon triple bond of the alkyne. Thus, the hydro-
aminations of phenylacetylene and 1-phenylpropyne
with tert-butylamine are easier than those with cyclo-
hexylamine (entries 1 and 3, and 5 and 7). In contrast
to the asymmetric alkynes, the reaction of diphen-
ylacetylene with cyclohexylamine is favored with regard
to the hydroamination of this alkyne with tert-but-
ylamine (entries 9 and 11). Among the sterically less
demanding amines cyclohexylamine and 2,6-dimeth-
ylaniline, the latter always gives better results than the
first one (entries 1 and 2, 5 and 6, and 9 and 10).
However, among the sterically more demanding amines
tert-butylamine and 2,6-diisopropylaniline, the alkyl-
amine gives better results than the arylamine for the
hydroamination of phenylacetylene and 1-phenyl-
propyne (entries 3 and 4, and 7 and 8). In contrast to
the asymmetric alkynes, the hydroamination of di-
Complex CpNTiCl3 also reacts with LiNH(2,6-iPr2C6H3).
The reaction affords the amido-imido derivative {(2,6-
iPr2C6H3)NH}CpNTi{N(2,6-iPr2C6H3)}, which, in con-
trast to the previously mentioned compounds, contains
a pendant dimethylamino group strongly coordinated
to the metal center both in the solid state and in
solution. Although unsaturated amido-imido-titanium
species related to this compound have been proposed
as active catalysts for the hydroamination of terminal
alkynes,17b,d,e,g it is catalytically inactive. However, the
trimethyl derivative CpNTiMe3 has been found to be a
very efficient catalyst precursor for the regioselective
anti-Markovnikov hydroamination of phenylacetylene
and 1-phenylpropyne, and the hydroamination of di-

Ti Complexes Containing a Cyclopentadienyl Ligand
Organometallics, Vol. 24, No. 21, 2005 5091
119.1 (C5H4), 78.1 (TiMe), 62.0 (CH2N), 48.3 (NMe2), 25.2
(C5H4CH2). 13C{1H} NMR (75.42 MHz, C7D8, 233 K, plus
APT): δ 135.3 (Cipso-C5H4), 120.0, 118.9 (C5H4), 77.9 (TiMe),
61.8 (CH2N), 48.3 (NMe2), 24.4 (C5H4CH2).
phenylacetylene with cyclohexylamine, 2,6-dimethyl-
aniline, tert-butylamine, and 2,6-diisopropylaniline. The
reactions lead to the corresponding enamine-imine
mixtures, which are transformed into the secondary
amines by reduction with molecular hydrogen in the
presence of PtO2.
In conclusion, this paper shows the preparation and
characterization of new seven- and six-coordinate tita-
nium complexes containing the [2-(dimethylamino)-
ethyl]cyclopentadienyl ligand, analyzes the behavior of
the pendant aminoalkyl group of these compounds in
the solid state and in solution, and reveals the existence
of a new titanium system to promote the intermolecular
catalytic regioselective anti-Markovnikov hydroamina-
tion of asymmetric alkynes.
Preparation of CpNTiMe2Cl (3). The same procedure
described for 2 was followed, except that 1 (812 mg, 2.79 mmol)
and 2 equiv of MgClMe 3 M in tetrahydrofuran (1.86 mL, 5.58
mmol) were used. The product was obtained as a red solid.
Yield: 351 mg (50%). Anal. Calcd for C11H20ClNTi: C, 52.90;
1
H, 8.09; N, 5.61. Found: C, 52.43; H, 8.47; N, 5.80. H NMR
(300 MHz, C7D8, 333 K): δ 6.16, 5.84 (both vt, 3+4J ) 6.0, each
2H, C5H4), 2.14 (m, 4H, CH2CH2), 2.02 (s, 6H, NMe2), 1.21 (s,
6H, TiMe2). 1H NMR (300 MHz, C7D8, 213 K): δ 6.21, 5.54
(both m, each 2H, C5H4), 1.82 (br s, 6H, NMe2), 1.53 (m, 2H,
C5H4CH2), 1.40 (m, 2H, CH2N), 1.20 (br s, 6H, TiMe2). 13C-
{1H} NMR (75.42 MHz, C7D8, 293 K, plus APT and HET-
COR): δ 133.0 (Cipso-C5H4), 117.4, 114.5 (C5H4), 68.6 (TiMe2),
62.1 (CH2N), 47.7 (NMe2), 25.9 (C5H4CH2). 13C{1H} NMR
(75.42 MHz, C7D8, 233 K, plus APT and HETCOR): δ 132.7
(Cipso-C5H4), 117.3, 114.0 (C5H4), 68.3 (TiMe2), 62.2 (CH2N),
48.0 (NMe2), 25.0 (C5H4CH2).
Experimental Section
General Methods and Instrumentation. All reactions
were carried out under argon with rigorous exclusion of air
using Schlenk-line or drybox techniques. Solvents were dried
by the usual procedures and distilled under argon prior to use.
The starting material CpNTiCl3 (1) was prepared by the
published method.12 Diphenylacetylene was dissolved in CH2-
Cl2, dried with Na2SO4, and recovered by evaporation of the
solvent. Phenylacetylene and 1-phenylpropyne were distilled
and amines were distilled from CaH2 and stored in the drybox.
All other reagents were purchased from commercial sources
and were used without further purification. The course of the
catalytic reactions was followed using a Hewlett-Packard 5890
series gas chromatograph with a flame ionization detector,
using a 100% cross-linked methyl silicone gum column (30 m
× 0.25 mm, with 0.25 µm film thickness) and n-octane as the
internal standard. The oven conditions used are as follows:
35 °C (hold 6 min) to 280 °C at 25 °C/min (hold 5 min). The
reaction products were identified by GC-MS and by 1H and
13C{1H} NMR spectroscopies. GC-MS experiments were run
on an Agilent 5973 mass selective detector interfaced to an
Agilent 6890 series gas chromatograph system. Samples were
injected into a 30 m × 250 µm HP-5MS 5% phenyl methyl
siloxane column with a film thickness of 0.25 µm (Agilent).
The GC oven temperature was programmed as follows: 35 °C
for 6 min to 280 °C at 25 °C/min for 5 min. The carrier gas
was helium at a flow of 1 mL/min.
Preparation of CpNTiMe3 (4). The same procedure de-
scribed for 2 was followed, except that 1 (500 mg, 1.72 mmol)
and 3 equiv of MgClMe 3 M in tetrahydrofuran (1.70 mL, 5.16
mmol) were used. The product was obtained as an orange oil.
Yield: 217 mg (55%). Anal. Calcd for C12H23NTi: C, 62.90; H,
1
10.14; N, 6.11. Found: C, 62.43; H, 10.37; N, 6.15. H NMR
(300 MHz, C7D8, 303 K): δ 5.90, 5.81 (both vt, 3+4J ) 6.0, each
2H, C5H4), 2.29 (m, 2H, C5H4CH2), 2.25 (m, 2H, CH2N), 2.03
1
(s, 6H, NMe2), 1.13 (s, 9H, TiMe3). H NMR (300 MHz, C7D8,
183 K): δ 6.32, 5.49 (both m, each 2H, C5H4), 1.63 (br s, 6H,
NMe2), 1.57 (m, 2H, C5H4CH2), 1.41 (m, 2H, CH2N), 1.08 (s,
9H, TiMe3). 13C{1H} NMR (75.42 MHz, C7D8, 293 K, plus APT
and HETCOR): δ 131.1 (Cipso-C5H4), 113.9, 112.5 (C5H4), 61.6
(TiMe3), 61.2 (CH2N), 45.9 (NMe2), 28.3 (C5H4CH2). 13C{1H}
NMR (75.42 MHz, C7D8, 203 K, plus APT): δ 130.3 (Cipso-C5H4),
115.0, 111.3 (C5H4), 63.0 (CH2N), 59.9 (TiMe3), 47.8 (NMe2),
24.8 (C5H4CH2).
Preparation of CpNTiCl(µ-O)2ClTiCpN (5). In an NMR
tube, complex CpNTiMe2Cl (3) (20 mg, 0.08 mmol) was dis-
solved in wet C6D6 or C7D8. The tube was periodically checked
by 1H NMR spectroscopy. After 7 days, the transformation of
3 into 5 was complete. During that time, a few crystals of 5
suitable for the X-ray diffraction were obtained. Attempts to
obtain this product by addition of a stoichiometric amount of
water to toluene solutions of 3 led to decomposition. Anal.
Calcd for C18H28Cl2N2O2Ti2: C, 45.87; H, 6.00; N, 5.95.
1H and 13C{1H} NMR spectra were recorded on either a
Varian UNITY 300, a Varian Gemini 2000, a Bruker AXR 300,
or a Bruker Avance 400 MHz instrument. Chemical shifts
(expressed in parts per million) are referenced to residual
solvent peaks (1H, 13C{1H}). Coupling constants, J, are given
in hertz. C, H, and N analyses were carried out in a Perkin-
Elmer 2400 CHNS/O analyzer.
1
Found: C, 45.66; H, 5.47; N, 6.19. H NMR (300 MHz, C7D8,
333 K): δ 6.08, 6.04 (both m, each 2H, C5H4), 2.60 (m, 2H,
1
C5H4CH2), 2.44 (m, 2H, CH2N), 2.13 (s, 6H, NMe2). H NMR
(300 MHz, C7D8, 233 K): δ 6.08, 5.89 (both m, each 2H, C5H4),
2.40 (m, 2H, C5H4CH2), 2.05 (m, 2H, CH2N), 1.87 (br s, 6H,
NMe2). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 129.9 (Cipso-C5H4), 113.5, 113.4 (C5H4), 60.6
(CH2N), 45.5 (NMe2), 28.4 (C5H4CH2).
Preparation of CpNTiMeCl2 (2). To an orange suspension
of 1 (537 mg, 1.85 mmol) in 18 mL of diethyl ether at -40 °C
was added dropwise 1.0 equiv of MgClMe 3 M in tetrahydro-
furan (0.62 mL, 1.85 mmol). After addition, the mixture was
warmed to room temperature and stirred for 4 h. The volatiles
were removed under reduced pressure, and the residue was
extracted with pentane (3 × 40 mL). The resultant brown
solution was concentrated to ca. 3 mL, and a brown solid
appeared, which was separated by decantation, washed with
(2 × 3 mL) pentane, and dried in vacuo. Yield: 214 mg (43%).
Anal. Calcd for C10H17Cl2NTi: C, 44.46; H, 6.35; N, 5.19.
Preparation of {(2,6-iPr2C6H3)NH}CpNTi{N(2,6-iPr2-
C6H3)} (6). To an orange suspension of 1 (597 mg, 2.05 mmol)
in 10 mL of diethyl ether at -40 °C was added a precooled
(-40 °C) solution of LiNH(2,6-iPr2C6H3) (1.25 g, 6.85 mmol)
in 15 mL of diethyl ether. After addition, the mixture was
warmed to room temperature and stirred for 18 h. The mixture
was filtered and concentrated to ca. 5 mL. A yellow solid
appeared, which was separated by decantation, washed with
(2 × 3 mL) pentane, and dried in vacuo. Yield: 462 mg (42%).
Anal. Calcd for C33H49N3Ti: C, 73.98; H, 9.24; N, 7.84.
1
Found: C, 44.57; H, 6.53; N, 5.23. H NMR (300 MHz, C7D8,
1
363 K): δ 6.40, 5.99 (both m, each 2H, C5H4), 2.17 (m, 4H,
CH2CH2), 2.09 (s, 6H, NMe2), 1.70 (s, 3H, TiMe). 1H NMR (300
MHz, C7D8, 223 K): δ 6.34, 5.68 (both m, each 2H, C5H4), 1.95
(br s, 6H, NMe2), 1.83 (s, 3H, TiMe), 1.76 (m, 2H, CH2N), 1.46
(br t, 3J ) 6.6, 2H, C5H4CH2). 13C{1H} NMR (75.42 MHz, C7D8,
293 K, plus APT and HETCOR): δ 135.5 (Cipso-C5H4), 120.2,
Found: C, 73.55; H, 9.19; N, 7.66. H NMR (300 MHz, C6D6,
293 K): δ 8.81 (s, 1H, NH), 7.21-6.85 (m, 6H, C6H3), 6.38,
6.33, 5.83, 5.48 (all m, each 1H, C5H4), 4.25, 3.74 (both sept,
3J ) 6.9, each 2H, CH(CH3)2), 2.50-2.41 (m, 1H, CHHN), 2.26,
2.25 (both s, each 3H, NMe2), 2.16-1.97 (m, 3H, C5H4CH2-
3
CHHN), 1.30, 1.27, 1.26, 1.21 (all d, J ) 6.9, each 6H, CH-

5092 Organometallics, Vol. 24, No. 21, 2005
Esteruelas et al.
(CH3)2). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 155.9, 154.0 (Cipso-N), 142.8, 138.8 (o-C6H3), 131.0
(Cipso-C5H4), 122.5, 121.8, 120.4 (C6H3), 115.4, 108.3, 106.6,
106.0 (C5H4), 69.4 (CH2N), 50.1, 49.3 (NMe2), 28.2, 27.4 (CH-
(CH3)2), 25.4 (C5H4CH2), 24.5, 24.2, 23.7, 23.6 (CH(CH3)2).
Determination of Constants and Thermodynamic
Parameters for the Equilibriums Shown in Eq 1. Vari-
able-temperature 1H NMR spectra of 2 (183-363 K), 3 (213-
333 K), 4 (183-303 K), and 5 (233-333 K) were recorded in
toluene-d8. Equilibrium constants, K, were derived from the
temperature-dependent δ(1H) of the methylene signals CpCH2
and NCH2 using eq 2. Thermodynamic parameters were
calculated from the equilibrium constants according to eq 6.
CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 165.4 (CH), 138.9, 134.3 (Cipso Ph), 129.3, 128.7,
128.5, 126.9 (Ph), 125.6 (Cipso Ph), 124.3 (Ph), 43.5 (CH2), 18.2
(CH3). MS: m/z 223 (M+), 208 (M+ - CH3), 193 (M+ - CH3).
1
PhCH2CH2NH-2,6-Me2C6H3: H NMR (300 MHz, C6D6, 293
K): δ 7.19-6.81 (m, 8H, Ph), 3.05 (t, J ) 6.9, 2H, CH2N), 2.59
(t, J ) 6.9, 2H, PhCH2), 2.02 (s, 6H, CH3). 13C{1H} NMR (75.42
MHz, C6D6, 293 K, plus APT): δ 146.5, 140.0, 129.5 (Cipso Ph),
129.2, 129.1, 128.7, 126.5, 122.1 (Ph), 49.4 (CH2N), 37.0
(PhCH2), 18.2 (CH3).
Hydroamination of Phenylacetylene with tert-Butyl-
amine. PhCHdCHNHtBu: 1H NMR (300 MHz, C6D6, 293
K): δ 7.23-6.96 (m, 5H, Ph), 6.71 (dd, J ) 12.9, J ) 13.5, 1H,
dCH), 5.40 (d, J ) 13.5, 1H, PhCHd), 3.16 (br d, J ) 12.9,
1H, NH), 0.90 (s, 9H, tBu). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT and HETCOR): δ 140.1 (Cipso), 132.6 (dCH),
128.8, 124.1, 123.9 (Ph), 102.2 (PhCHd), 50.3 (C(CH3)3), 29.7
∆S° ∆H°
ln K )
-
(6)
R
RT
1
(C(CH3)3). PhCH2CHdNtBu: H NMR (300 MHz, C6D6, 293
Reasonable values for δmin and δmax were obtained by
computer-assisted iteration: δmin and δmax were optimized in
such a way that plotting of ln K versus 1/T gives the straightest
line possible.
K): δ 7.47 (t, J ) 5.1, 1H, CH), 7.23-6.96 (m, 5H, Ph), 3.44
(d, J ) 5.1, 2H, CH2), 1.10 (s, 9H, tBu). 13C{1H} NMR (75.42
MHz, C6D6, 293 K, plus APT and HETCOR): δ 155.9 (CH),
137.7 (Cipso Ph), 129.3, 127.5, 126.7 (Ph), 56.6 (C(CH3)3), 43.3
(CH2), 29.5 (C(CH3)3). MS: m/z 175 (M+), 160 (M+ - CH3).
PhCH2CH2NHtBu: 1H NMR (300 MHz, C6D6, 293 K): δ 7.18-
7.08 (m, 5H, Ph), 2.70-2.65 (m, 4H, CH2CH2), 0.96 (s, 9H, tBu),
0.59 (br s, 1H, NH). 13C{1H} NMR (75.42 MHz, C6D6, 293 K,
plus APT): δ 141.1 (Cipso Ph), 129.1, 128.6, 126.2 (Ph), 49.8
(C(CH3)3), 44.1 (CH2N), 37.8 (PhCH2), 28.9 (C(CH3)3). MS: m/z
177 (M+), 162 (M+ - CH3).
General Procedure for Hydroamination. A Schlenk
tube equipped with a Teflon stopcock and a magnetic stirring
bar was charged with the alkyne (2.40 mmol), the amine (2.64
mmol), complex 4 (27.5 mg, 0.12 mmol, 5.0% mol), toluene (2
mL), and n-octane (2.40 mmol). The Schlenk was removed from
the glovebox and heated at 100 °C. The reaction was monitored
by periodic GC analysis of samples removed with a syringe.
Either when the reaction was complete or after 24 h, the
volatiles were removed under reduced pressure and the residue
was analyzed by 1H and 13C{1H} NMR spectroscopy and by
GC-MS.
Hydroamination of Phenylacetylene with 2,6-Diiso-
1
propylaniline. PhCHdCHNH-2,6-iPr2C6H3: H NMR (300
MHz, C6D6, 293 K): δ 7.15-6.97 (m, 8H, Ph), 6.65 (dd, J )
7.2, J ) 14.4, 1H, dCHN), 5.19 (d, J ) 14.4, 1H, PhCHd),
4.24 (br d, J ) 7.2, 1H, NH), 3.19 (sept, J ) 6.9, 2H, CH(CH3)2),
1.18 (d, J ) 6.9, 12H, CH(CH3)2). 13C{1H} NMR (75.42 MHz,
C6D6, 293 K, plus APT): δ 146.5, 139.6, 135.8 (Cipso Ph), 134.9
(dCHN), 129.3, 128.7, 128.5, 125.6, 124.0 (Ph), 101.3 (PhCHd
), 28.1 (CH(CH3)2), 23.9 (CH(CH3)2). PhCH2CHdN-2,6-
iPr2C6H3: 1H NMR (300 MHz, C6D6, 293 K): δ 7.41 (t, J )
5.1, 1H, CH), 7.15-6.97 (m, 8H, Ph), 3.53 (d, J ) 5.1, 2H, CH2),
3.02 (sept, J ) 6.9, 2H, CH(CH3)2), 1.09 (d, J ) 6.9, 12H, CH-
(CH3)2). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT): δ
164.8 (CH), 149.6, 137.6, 136.3 (Cipso Ph), 129.4, 128.9, 127.0,
124.4, 123.2 (Ph), 43.6 (CH2), 27.8 (CH(CH3)2)), 23.3 (CH-
(CH3))2. MS: m/z 279 (M+), 188 (M+ - C7H7). PhCH2-
CH2NH-2,6-iPr2C6H3: 1H NMR (300 MHz, C6D6, 293 K): δ
7.20-7.10 (m, 8H, Ph), 3.17 (sept, J ) 6.9, 2H, CH(CH3)2), 3.15
(t, J ) 6.9, 2H, CH2N), 2.81 (t, J ) 6.9, 2H, PhCH2), 1.21 (d,
J ) 6.9, 12H, CH(CH3)2). 13C{1H} NMR (75.42 MHz, C6D6, 293
K, plus APT and HETCOR): δ 143.7, 143.0, 140.2 (Cipso Ph),
129.1, 128.7, 126.5, 124.4, 123.8 (Ph), 53.2 (CH2N), 37.3
(PhCH2), 27.8 (CH(CH3)2), 24.4 (CH(CH3)2). MS: m/z 281 (M+),
190 (M+ - C7H7).
General Procedure for Hydrogenation. In a Fischer-
Porter bottle, PtO2 (15 mg, 0.07 mmol) was stirred in THF
(3.0 mL) at 25 °C under 1 atm of H2 for 10 min. A solution of
the crude hydroamination product in THF (3.0 mL) was then
added. The resulting mixture was stirred under 3 atm of H2
at 25 °C for 48 h. Filtration, concentration, and purification
by flash chromatography on silica gel afforded the amines,
1
whose purity was checked by H and 13C{1H} NMR spectros-
copy and by GC-MS.
Hydroamination of Phenylacetylene with Cyclohex-
1
ylamine. PhCHdCHNHCy: H NMR (300 MHz, C6D6, 293
K): δ 7.43-6.95 (m, 5H, Ph), 6.56 (dd, J ) 8.7, J ) 14.4, 1H,
dCHN), 5.37 (d, J ) 14.4, 1H, PhCHd), 3.00 (br t, J ) 8.7,
1H, NH), 2.80-2.70 (m, 1H, CH, Cy), 1.79-0.80 (m, 10H, CH2).
13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT and
HETCOR): δ 137.5 (Cipso Ph), 134.5 (dCHN), 128.3, 127.1,
123.5 (Ph), 98.7 (PhCHd), 52.7 (CH, Cy), 33.3, 25.8, 24.8 (CH2).
PhCH2CHdNCy: 1H NMR (300 MHz, C6D6, 293 K): δ 7.90-
7.87 (m, 1H, Ph), 7.43 (t, J ) 5.1, 1H, CHdN), 7.43-6.95 (m,
4H, Ph), 3.39 (d, J ) 5.1, 2H, PhCH2), 2.80-2.70 (m, 1H, CH,
Cy), 1.79-0.80 (m, 10H, CH2, Cy). 13C{1H} NMR (75.42 MHz,
C6D6, 293 K, plus APT and HETCOR): δ 159.5 (CHdN), 140.6
(Cipso Ph), 129.3, 128.8, 123.9 (Ph), 69.5 (CH, Cy), 42.7 (PhCH2),
33.9, 25.9, 24.8 (CH2, Cy). MS: m/z 200 (M+). PhCH2CH2-
NHCy: 1H NMR (300 MHz, C6D6, 293 K): δ 7.34-7.07 (m,
5H, Ph), 2.80-2.64 (m, 4H, CH2CH2), 2.32-2.25 (m, 1H, CH),
1.74-0.99 (m, 10H, CH2, Cy). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT): δ 141.0 (Cipso Ph), 129.1, 128.6, 126.2 (Ph),
56.6 (CH), 48.5 (CH2), 37.2 (CH2), 33.7, 26.4, 24.9 (CH2, Cy).
Hydroamination of Phenylacetylene with 2,6-Di-
methylaniline. PhCHdCHNH-2,6-Me2C6H3: 1H NMR: δ
7.19-6.90 (m, 8H, Ph), 6.56 (dd, J ) 14.1, J ) 6.9, 1H, dCHN),
5.22 (d, J ) 14.1, 1H, PhCHd), 4.32 (br d, J ) 6.9, 1H, NH),
2.08 (s, 6H, CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus
APT and HETCOR): δ 132.9 (dCHN), 139.4, 136.4, 134.3 (Cipso
Ph), 129.5, 128.8, 128.6, 127.4, 125.6 (Ph), 101.5 (PhCHd), 18.1
(CH3). PhCH2CHdN-2,6-Me2C6H3: 1H NMR (300 MHz, C6D6,
293 K): δ 7.95-7.92 (m, 1H, Ph), 7.21 (t, J ) 5.1, 1H, CH),
7.14-6.90 (m, 7H, Ph), 3.48 (d, J ) 5.1, 2H, CH2), 2.02 (s, 6H,
Hydroamination of 1-Phenylpropyne with Cyclohex-
ylamine. PhCHdC(Me)NHCy: 1H NMR (300 MHz, C6D6, 293
K): δ 7.22-6.97 (m, 5H, Ph), 5.40 (s, 1H, CHd), 2.57 (br d,
1H, NH), 2.92-2.84 (m, 1H, CH, Cy), 1.73 (s, 3H, CH3), 1.74-
1.62 (m, 10H, CH2). 13C{1H} NMR (75.42 MHz, C6D6, 293 K,
plus APT and HETCOR): δ 140.9, 137.8 (Cipso + dC), 131.8,
128.5, 123.6 (Ph), 96.4 (CHd), 59.4 (CH, Cy), 34.9, 26.2, 25.0
1
(CH2), 14.1 (CH3). PhCH2C(Me)dNCy: H NMR (300 MHz,
C6D6, 293 K): δ 7.22-6.97 (m, 5H, Ph), 3.45 (s, 2H, PhCH2),
3.22-3.13 (m, 1H, CH), 1.74-1.62 (m, 10H, CH2, Cy), 1.39 (s,
3H, CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT
and HETCOR): δ 164.2 (CdN), 138.8 (Cipso Ph), 129.3, 128.7,
126.6 (Ph), 59.2 (CH), 49.7 (PhCH2), 33.9, 26.0, 24.8 (CH2, Cy),
15.3 (CH3). MS: m/z 215 (M+), 200 (M+ - CH3). PhCH2CH-
1
(Me)NHCy: H NMR (300 MHz, C6D6, 293 K): δ 7.22-7.09
(m, 5H, Ph), 3.02 (sext, J ) 6.3, 1H, CH), 2.68 (dd, J ) 13.2,
J ) 6.3, 1H, PhCH2), 2.49 (dd, J ) 6.3, J ) 13.2, 1H, PhCH2),
2.49 (m, 1H, CH, Cy), 1.85-1.49 (m, 6H, CH2, Cy), 1.27-0.81

Ti Complexes Containing a Cyclopentadienyl Ligand
Organometallics, Vol. 24, No. 21, 2005 5093
(m, 4H, CH2, Cy), 0.99 (d, J ) 6.3, 3H, CH3), 0.62 (br s, 1H,
NH). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT,
HETCOR and COSY): δ 140.4 (Cipso Ph), 129.7, 128.5, 126.2
(Ph), 53.2 (CH, Cy), 50.9 (CH), 44.4 (PhCH2), 34.7, 33.7, 26.4,
25.2, 25.0 (CH2, Cy), 21.1 (CH3). MS: m/z 217 ([M+), 126 (M+
- C7H7).
Hydroamination of Diphenylacetylene with Cyclo-
hexylamine. PhCHdC(Ph)NHCy: A 1:1 mixture of E and
1
Z isomers was obtained. H NMR (300 MHz, C6D6, 293 K): δ
7.63-7.60 (m, 2H, Ph), 7.45-7.39 (m, 2H, Ph), 7.27-6.99 (m,
16H, Ph), 5.69 (s, 1H, CHd), 5.61 (s, 1H, CHd), 4.11 (br s,
1H, NH), 4.08 (br s, 1H, NH), 3.27-3.14 (m, 1H, CH, Cy), 3.04
(m, 1H, CH, Cy), 1.95-0.83 (m, 20H, CH2). 13C{1H} NMR
(75.42 MHz, C6D6, 293 K, plus APT and HETCOR): δ 147.2,
145.5, 140.7, 140.2, 139.9, 139.0 (Cipso Ph + dC), 129.9, 129.4,
129.3, 128.9, 128.4, 128.3, 126.7, 126.5, 125.5, 123.7 (Ph), 106.8
(CHd), 98.3 (CHd), 53.1, 51.3 (CH, Cy), 34.3, 34.1, 34.0, 26.1,
25.9, 25.6, 24.5, 24.3 (CH2). PhCH2C(Ph)dNCy: 1H NMR (300
MHz, C6D6, 293 K): δ 8.00-7.97 (m, 2H, Ph), 7.52-6.99 (m,
8H, Ph), 3.83 (s, 2H, PhCH2), 3.63-3.54 (m, 1H, CH), 1.95-
0.83 (m, 10H, CH2, Cy). 13C{1H} NMR (75.42 MHz, C6D6, 293
K, plus APT and HETCOR): δ 161.8 (CdN), 140.6, 137.8 (Cipso
Ph), 129.0, 128.5, 128.3, 128.1, 127.8 (Ph), 60.0 (CH), 34.6, 34.1
(CH2, Cy), 32.9 (PhCH2), 26.0, 25.1, 24.8 (CH2, Cy). MS: m/z
Hydroamination of 1-Phenylpropyne with 2,6-Di-
methylaniline. PhCHdC(Me)NH-2,6-Me2C6H3: 1H NMR: δ
7.23-6.96 (m, 8H, Ph), 5.12 (s, 1H, CHd), 4.05 (s, 1H, NH),
2.15 (s, 6H, CH3), 1.82 (s, 3H, CH3). 13C{1H} NMR (75.42 MHz,
C6D6, 293 K, plus APT): δ 140.1, 139.9, 136.7, 136.0 (Cipso Ph
+ dC), 129.3, 128.5, 128.4, 126.7, 124.0 (Ph), 99.1 (CHd), 18.2
(CH3), 17.9 (CH3). PhCH2C(Me)dN-2,6-Me2C6H3: 1H NMR
(300 MHz, C6D6, 293 K): δ 7.23-6.96 (m, 8H, Ph), 3.53 (s,
2H, CH2), 1.97 (s, 6H, CH3), 1.24 (s, 3H, CH3). 13C{1H} NMR
(75.42 MHz, C6D6, 293 K, plus APT and HETCOR): δ 169.2
(CdN), 149.4, 137.8 (Cipso Ph), 129.5, 128.8, 128.3, 126.9 (Ph),
125.8 (Cipso Ph), 122.9 (Ph), 48.2 (CH2), 18.3 (CH3), 18.0 (CH3).
MS: m/z 237 (M+), 146 (M+ - C7H7). PhCH2CH(Me)NH-2,6-
Me2C6H3: 1H NMR (300 MHz, C6D6, 293 K): δ 7.15-6.83 (m,
8H, Ph), 3.44-3.34 (m, 1H, CH), 2.80-2.74 (m, 2H, 1H, CH2
+ NH), 2.31 (dd, J ) 8.4, J ) 13.2, 1H, CH2), 2.09 (s, 6H, CH3),
0.87 (d, J ) 6.3, 3H, CH3). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT): δ 145.3, 139.8 (Cipso Ph), 129.7 (Ph), 129.6
(Cipso Ph), 129.3, 128.5, 126.3, 121.9 (Ph), 54.2 (CH), 44.4 (CH2),
20.5 (CH3), 18.8 (CH3). MS: m/z 239 (M+), 148 (M+ - C7H7).
1
277 (M+), 186 (M+ - C7H7). PhCH2CH(Ph)NHCy: H NMR
(300 MHz, C6D6, 293 K): δ 7.36-7.02 (m, 10H, Ph), 4.04 (dd,
J ) 5.7, J ) 8.1, 1H, CHPh), 2.86 (dd, J ) 13.5, J ) 5.7, 1H,
PhCH2), 2.76 (dd, J ) 8.1, J ) 13.5, 1H, PhCH2), 2.28 (m, 1H,
CH, Cy), 1.78 (br d, J ) 12, 1H, NH), 1.44-0.70 (m, 10H, CH2,
Cy). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT): δ
145.6, 139.6 (Cipso Ph), 129.6, 128.5, 127.6, 127.1, 126.5 (Ph),
61.4 (CHPh), 53.4 (CH, Cy), 46.3 (PhCH2), 34.9, 32.7, 26.2,
25.1, 24.6 (CH2, Cy). MS: m/z 188 (M+ - C7H7).
Hydroamination of 1-Phenylpropyne with tert-But-
ylamine. PhCHdC(Me)NHtBu: 1H NMR (300 MHz, C6D6,
293 K): δ 7.21-6.96 (m, 5H, Ph), 5.58 (s, 1H, CHd), 2.60 (br
s, 1H, NH), 1.70 (s, 3H, CH3), 1.16 (s, 9H, tBu). 13C{1H} NMR
(75.42 MHz, C6D6, 293 K, plus APT and HETCOR): δ 140.9,
139.1 (Cipso Ph + dC), 128.9, 128.2, 123.8 (Ph), 99.7 (CHd),
54.6 (C(CH3)3)), 29.4 (C(CH3)3)), 19.4 (CH3). PhCH2C(Me)d
NtBu: 1H NMR (300 MHz, C6D6, 293 K): δ 7.21-6.96 (m, 5H,
Ph), 3.40 (s, 2H, CH2), 1.50 (s, 3H, CH3), 1.25 (s, 9H, tBu).
13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT): δ 164.2
(CdN), 140.1 (Cipso Ph), 129.2, 128.7, 126.6 (Ph), 51.6 (CH2),
50.9 (C(CH3)3), 30.4 (C(CH3)3), 19.9 (CH3). MS: m/z 189 (M+),
174 (M+ - CH3). PhCH2CH(Me)NHtBu: 1H NMR (300 MHz,
C6D6, 293 K): δ 7.18-7.08 (m, 5H, Ph), 2.85 (sext, J ) 6.3,
1H, CH), 2.59 (dd, J ) 6.3, J ) 13.2, 1H, CH2), 2.46 (dd, J )
6.3, J ) 13.2, 1H, CH2), 0.97 (d, J ) 6.3, 3H, CH3), 0.92 (s,
9H, tBu), 0.44 (br s, 1H, NH). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT): δ 140.8 (Cipso Ph), 129.8, 128.4, 126.2 (Ph),
50.5 (C(CH3)3), 49.2 (CH), 46.9 (CH2), 29.9 (C(CH3)3), 24.2
(CH3). MS: m/z 191 (M+), 176 (M+ - CH3).
Hydroamination of 1-Phenylpropyne with 2,6-Diiso-
propylamine. PhCHdC(Me)NH-2,6-iPr2C6H3. 1H NMR (300
MHz, C6D6, 293 K): δ 7.24-6.92 (m, 8H, Ph), 5.09 (s, 1H,
CHd), 3.94 (s, 1H, NH), 3.24 (sept, J ) 6.9, 2H, CH(CH3)2),
1.81 (s, 3H, CH3), 1.19 (d, J ) 6.9, 12H, CH(CH3)2). 13C{1H}
NMR (75.42 MHz, C6D6, 293 K, plus APT): δ 147.3, 142.1,
140.0, 135.7 (Cipso Ph + dC), 129.3, 128.5, 128.2, 124.0, 123.9
(Ph), 99.9 (CHd), 28.3 (CH(CH3)2), 24.0 (CH(CH3)2), 17.9 (CH3).
PhCH2C(Me)dN-2,6-iPr2C6H3: 1H NMR (300 MHz, C6D6, 293
K): δ 7.24-6.92 (m, 8H, Ph), 3.54 (s, 2H, CH2), 2.84 (sept, J
) 6.9, 2H, CH(CH3)2), 1.33 (s, 3H, CH3), 1.17, 1.06 (both d, J
) 6.9, each 6H, CH(CH3)2). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT): δ 169.3 (CdN), 146.9, 137.8, 136.3 (Cipso
Ph), 129.5, 128.7, 126.9, 123.7, 123.2 (Ph), 48.4 (CH2), 28.1
(CH(CH3)2), 23.2, 22.8 (CH(CH3)2), 18.9 (CH3). MS: m/z 293
Hydroamination of Diphenylacetylene with 2,6-Di-
methylaniline. PhCHdC(Ph)NH-2,6-Me2C6H3: 1H NMR
(300 MHz, C6D6, 293 K): δ 7.51-7.48 (m, 2H, Ph), 7.12-6.76
(m, 11H, Ph), 5.31 (s, 1H, CHd), 4.23 (s, 1H, NH), 2.16 (s, 6H,
CH3). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT): δ
143.6, 139.1, 138.6, 137.8, 135.2 (Cipso Ph + dC), 129.8, 128.9,
128.8, 128.5, 128.1, 125.9, 124.2 (Ph), 101.0 (CHd), 17.9 (CH3).
PhCH2C(Ph)dN-2,6-Me2C6H3: 1H NMR (300 MHz, C6D6, 293
K): δ 8.01-7.97 (m, 2H, Ph), 7.12-6.76 (m, 11H, Ph), 3.70 (s,
2H, CH2), 1.96 (s, 6H, CH3). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT): δ 166.2 (CdN), 149.2, 139.0, 136.7 (Cipso
Ph), 130.4, 129.1, 128.6, 128.5, 128.5, 128.3, 126.4 (Ph), 126.0
(Cipso Ph), 123.3 (Ph), 36.7 (CH2), 18.3 (CH3). MS: m/z 299 (M+),
208 (M+ - C7H7). PhCH2CH(Ph)NH-2,6-Me2C6H3: 1H NMR
(300 MHz, C6D6, 293 K): δ 7.20-6.87 (m, 13H, Ph), 4.35 (t, J
) 7.0, 1H, CH), 3.12 (dd, J ) 13.2, J ) 7.0, 1H, CH2), 2.93
(dd, J ) 13.2, J ) 7.0, 1H, CH2), 2.03 (s, 6H, CH3). 13C{1H}
NMR (75.42 MHz, C6D6, 293 K, plus APT): δ 145.1, 144.0,
139.0 (Cipso Ph), 129.8 (Ph), 129.7 (Cipso Ph), 129.6, 129.3, 128.7,
127.2, 126.6, 126.4, 122.0 (Ph), 63.7 (CH), 43.5 (CH2), 18.8
(CH3).
Hydroamination of Diphenylacetylene with tert-
Butylamine. PhCHdC(Ph)NHtBu: 1H NMR (300 MHz,
C6D6, 293 K): δ 7.51-6.81 (m, 10H, Ph), 5.79 (s, 1H, CHd),
2.96 (br s, 1H, NH), 1.12 (s, 9H, tBu). 13C{1H} NMR (75.42
MHz, C6D6, 293 K, plus APT): δ 145.1, 140.9, 139.7 (Cipso Ph
+ dC), 130.2, 128.6, 128.5, 128.1, 123.8 (Ph), 102.5 (CHd),
51.3 (C(CH3)3), 29.5 (C(CH3)3). MS: m/z 251 (M+), 194 (M+
-
C4H9). PhCH2CH(Ph)NHtBu: 1H NMR (300 MHz, C6D6, 293
K): δ 7.42-6.98 (m, 10H, Ph), 3.94 (dd, J ) 5.1, J ) 9.3, 1H,
CH), 2.84 (dd, J ) 5.1, J ) 13.5, 1H, CH2), 2.59 (dd, J ) 9.3,
J ) 13.5, 1H, CH2), 1.09 (br s, 1H, NH), 0.81 (s, 9H, tBu). 13C-
{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT): δ 148.5, 139.7
(Cipso Ph), 129.6, 128.5, 127.4, 126.7, 126.5 (Ph), 59.3 (CH), 50.8
(C(CH3)3), 47.5 (CH2), 29.8 (C(CH3)3). MS: m/z 253 (M+), 181
(M+ - C4H10N).
_
1
(M+), 202 (M+ C7H7). PhCH2CH(Me)NH-2,6-iPr2C6H3: H
NMR (300 MHz, C6D6, 293 K): δ 7.20-7.10 (m, 8H, Ph), 3.29
(m, 2H, 1H, CH(CH3)2, CH), 2.85 (m, 2H, 1H, CH2 + NH), 2.44
(dd, J ) 7.8, J ) 12.8, 1H, CH2), 1.22, 1.20 (both d, J ) 6.6,
6H, CH(CH3)2), 1.00 (d, J ) 6.3, 3H, CH3). 13C{1H} NMR (75.42
MHz, C6D6, 293 K, plus APT and HETCOR): δ 143.0, 141.9,
139.9 (Cipso Ph), 129.6, 128.5, 126.4, 124.1, 123.9 (Ph), 57.5
(CH), 44.3 (CH2), 27.7 (CH(CH3)2), 24.2 (CH(CH3)2), 24.0 (CH-
(CH3)2), 20.1 (CH3). MS: m/z 295 (M+), 204 (M+ - C7H7).
Hydroamination of Diphenylacetylene with 2,6-Diiso-
propylaniline. PhCHdC(Ph)NH-2,6-iPr2C6H3: 1H NMR
(300 MHz, C6D6, 293 K): δ 7.55-7.52 (m, 2H, Ph), 7.19-6.75
(m, 11H, Ph), 5.30 (s, 1H, CHd), 4.38 (s, 1H, NH), 3.36 (sept,
J ) 6.9, 2H, CH(CH3)2), 1.20 (d, J ) 6.9, 12H, CH(CH3)2). 13C-
{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT): δ 146.7, 146.1,
139.3, 138.9, 135.6 (Cipso Ph + dC), 129.6, 129.1, 128.9, 128.4,
128.1, 127.6, 124.2, 124.1 (Ph), 101.6 (CHd), 28.4 CH(CH3)2),

5094 Organometallics, Vol. 24, No. 21, 2005
Table 6. Crystal Data and Data Collection and Refinement for 2, 3, 5, and 6
Esteruelas et al.
2
3
5
6
Crystal Data
formula
C
10H17Cl2NTi
C11H20ClNTi
C18H28Cl2N2O2Ti2
471.12
yellow, irregular block
0.16,0.06,0.04
monoclinic, P21/n
8.4483(14)
C33H49N3Ti
molecular wt
270.05
249.63
535.65
color and habit
red, irregular block
0.20,0.10,0.08
orthorhombic, P212121
8.8802(6)
9.1973(7)
15.0299(11)
97.839(3)
1227.55(15)
4
1.461
red, irregular block
0.16,0.12,0.08
orthorhombic, P212121
8.9192(16)
9.1904(16)
15.249(3)
yellow, irregular block
0.20,0.16,0.06
monoclinic, P21/n
17.038(2)
11.1820(14)
17.564(2)
size, mm
symmetry, space group
a, Å
b, Å
7.8564(13)
14.967(3)
c, Å
â, deg
V, Å 3
Z
112.791(2)
1250.0(4)
984.1(0)
2
1.590
1819.0(7)
4
1.153
4
Dcalc, g cm-3
1.326
Data Collection and Refinement
diffractometer
λ(Mo KR), Å
Bruker Smart APEX
0.71073
graphite oriented
ω scans
monochromator
scan type
µ, mm-1
2θ, range, deg
temp, K
no. of data collected
no. of unique data
no. of params/restraints
R1a [F2 > 2σ(F2)]
wR2b [all data]
Sc [all data]
1.095
0.863
3, 57
1.098
0.302
3, 57
100.0(2)
28 350
3, 57
3, 57
100.0(2)
15 371
100.0(2)
14 992
100.0(2)
10 856
3035 (Rint ) 0.0528)
179/0
2961 (Rint ) 0.0924)
132/0
2354 (Rint ) 0.0438)
120/0
7500 (Rint ) 0.0996)
348/0
0.0317
0.0610
0.0389
0.0539
0.0479
0.1095
0.0843
0.1041
0.811
0.913
1.002
0.720
2
2
a R1(F) ) ∑||Fo| - |Fc||/∑|Fo|. b wR2(F2) ) {∑[w(Fo2 - Fc )2]/∑[w(Fo2)2]}1/2
.
c Goof ) S ) {∑[Fo2 - Fc )2]/(n - p)}1/2, where n is the number
of reflections and p is the number of refined parameters.
24.0 CH(CH3)2). MS: m/z 355 (M+), 264 (M+ - C7H7).
matrix least squares on F2 with SHELXL97,32 was similar for
all complexes, including isotropic and subsequently anisotropic
displacement parameters for all non-hydrogen atoms. The
hydrogen atoms were observed or calculated and refined freely
or using a restricted riding model, respectively. A summary
of crystal data and data collection and refinement details is
reported in Table 6.
1
PhCH2CH(Ph)NH-2,6-iPr2C6H3: H NMR (300 MHz, C6D6,
293 K): δ 7.18-7.07 (m, 13H, Ph), 4.21 (t, J ) 7.2, 1H, CH),
3.33 (dd, J ) 7.2, J ) 13.2, 1H, CH2), 3.10 (sept, J ) 6.9, 2H,
CH(CH3)2), 3.08 (dd, J ) 7.2, J ) 13.2, 1H, CH2), 1.26, 1.25
(d, JH-H ) 6.9, 6H, CH(CH3)2). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT and HETCOR): δ 143.5, 143.4, 141.7, 139.7
(Cipso Ph), 129.8, 128.4, 127.5, 127.3, 126.4, 124.4, 123.8, 123.7
(Ph), 67.6 (CH), 43.0 (CH2), 27.6 (CH(CH3)2), 24.3 (CH(CH3)2),
24.0 (CH(CH3)2).
Structural Analysis of Complexes 2, 3, 5, and 6. X-ray
data were collected for all complexes at 100.0(2) K on a Bruker
Smart APEX CCD diffractometer equipped with a normal
focus, 2.4 kW sealed tube source (Mo radiation, λ ) 0.71073
Å) operating at 50 kV and 40 mA. Data were collected over
the complete sphere by a combination of four sets. Each frame
exposure time was 10 or 30 s covering 0.3° in ω. Data were
corrected for absorption by using a multiscan method applied
with the SADABS program.31 The structures for all compounds
were solved by the Patterson method. Refinement, by full-
Acknowledgment. Financial support from the
MCYT of Spain (Proyect BQU2002-00606 and PPQ2000-
0488-P4-02) is acknowledged. A.C.M. thanks Repsol-
YPF for a grant.
Supporting Information Available: Crystal structure
determinations, including bond lengths and angles of com-
pounds 2, 3, 5, and 6. This material is available free of charge
via the Internet at http://pubs.acs.org.
OM050542V
(32) SHELXTL Package v. 6.1; Bruker-AXS: Madison, WI, 2000.
Sheldrick, G. M. SHELXS-86 and SHELXL-97; University of Go¨ttin-
gen: Go¨ttingen, Germany, 1997.
(31) Blessing, R. H. Acta Crystallogr. 1995, A51, 33. SADABS, Area-
detector absorption correction; Bruker-AXS: Madison, WI, 1996.