Imido and amido titanium complexes that contain a [OSSO]-type bis(phenolato) ligand: Synthesis, structures, and hydroamination catalysis

Article abstract of DOI:10.1002/ejic.200800977

Salt metathesis reaction of the imido complex [Ti(NR)-Cl ₂(NC₅H₅)₃] (R = tBu, C ₆H₃iPr₂-2,6) with 1 equiv. of the lithium salt of the corresponding [OSSO]-type bis(phenol) [edtbp

Full text of DOI:10.1002/ejic.200800977

FULL PAPER
DOI: 10.1002/ejic.200800977
Imido and Amido Titanium Complexes that Contain a [OSSO]-Type
Bis(phenolato) Ligand: Synthesis, Structures, and Hydroamination Catalysis
Bing Lian,[a] Thomas P. Spaniol,[a] Patricia Horrillo-Martínez,[b] Kai C. Hultzsch,[b][‡] and
Jun Okuda*[a]
Keywords: Titanium / N ligands / Bis(phenolato) ligand / Hydroamination / Homogeneous catalysis
Salt metathesis reaction of the imido complex [Ti(NR)-
Cl2(NC5H5)3] (R = tBu, C6H3iPr2-2,6) with 1 equiv. of the lith-
ium salt of the corresponding [OSSO]-type bis(phenol)
[edtbpH2: (HOC6H2-tBu2-4,6)2(SCH2CH2S); rac-(cydtbp)H2:
(HOC6H2-tBu2-4,6)2(S2C6H10-1,2)] afforded imido titanium
complexes [Ti(edtbp)(NtBu)(NC5H5)] (1), [Ti(edtbp)(NC6H3-
iPr2-2,6)(NC5H5)] (2), and [Ti{rac-(cydtbp)}(NtBu)(NC5H5)]
(3). The bis(dimethylamido)titanium complex [Ti(edtbp)-
(NMe2)2] (4) was synthesized by protonolysis of [Ti(NMe2)4]
with bis(phenol) edtbpH2. Reaction of [Ti(NMe2)Cl3] with the
lithium salt of the bis(phenol) gave the chloro dimethylamido
complex [Ti(edtbp)(NMe2)Cl] (5) in high yield. All complexes
were characterized by NMR spectroscopy and elemental
analysis. Additionally, complexes 1 and 5 were studied by
X-ray diffraction analysis. Imido titanium complex 1 shows
moderate activity in the intramolecular hydroamination reac-
tion of 5-phenylpent-4-ynylamine. Complexes 1–3 catalyze
the intramolecular hydroamination of aminoalkenes.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
Introduction
Results and Discussion
The catalytic hydroamination, constituting the addition
of N–H across the carbon–carbon multiple bond, has be-
come an attractive carbon–nitrogen bond forming process
in the recent past.[1] In particular, group 4 metal systems
exhibit the catalytic performance distinct from other metal
systems.[2] We have recently introduced configurationally
Imido and Amidotitanium Complexes
Reaction of the imido precursor [Ti(NR)Cl2(NC5H5)3]
(R = tBu, C6H3iPr2-2,6) with one equiv. of the lithium salt
of the bis(phenol) [edtbpH2: (HOC6H2-tBu2-4,6)2-
(SCH2CH2S);
rac-(cydtbp)H2:
(HOC6H2-tBu2-4,6)2-
(S2C6H10-1,2)] generated in situ in THF/toluene mixture at
–35 °C led to the formation of the imido titanium com-
plexes 1–3 (Scheme 1). The new complexes were isolated as
crystals in high yield (80–87%) and characterized by 1H
and 13C NMR spectroscopy as well as by elemental analy-
sis. The 1H NMR spectrum of both [Ti(edtbp)(NtBu)-
(NC5H5)] (1) and [Ti(edtbp)(NC6H3iPr2-2,6)(NC5H5)] (2)
in C6D6 at room temperature shows an ABCD spin system
for the SCH2CH2S bridge with four sets of signals [2: δ =
2.60 (dm), 2.48 (dm), 2.24 (td), and 2.13 ppm (td)]. The 1H-
rigid titanium complexes containing
a
linked bis-
(phenolato) [OSSO]-type ligand that polymerize styrene iso-
specifically,[3a–3d,3g] and oligomerize α-olefins regioselectiv-
ely.[3e] Living polymerization of methyl methacrylate could
be achieved with the titanium enolate complex.[3f] The heli-
cal configuration around the metal center ensures the isos-
pecific polymerization of styrene and related monomers.[4]
To explore the suitability of this [OSSO]-type titanium sys-
tem for hydroamination reactions, we have prepared both
imido- and amidotitanium complexes containing this
[OSSO]-type ligand and investigated their hydroamination
reactivity. In the course of the preparation of this article,
Doye et al. reported that the amido titanium and zirconium
catalysts generated in situ with this type of ligand catalyze
the hydroamination of alkynes and alkenes.[2l]
13C HMQC spectrum gives the correlation of the H NMR
1
resonances with two 13C NMR resonances at δ = 37.74
(2.60 and 2.24 ppm) and 35.07 ppm (2.48 and 2.13 ppm),
respectively. In the 1H NMR spectrum of 2 four singlets for
the four tert-butyl groups are found (δ = 1.89, 1.71, 1.32,
and 1.23 ppm), indicating a rigid C1-symmetric molecular
1
structure in solution. According to H NMR spectroscopic
[a] Institute of Inorganic Chemistry, RWTH Aachen University,
Landoltweg 1, 52074 Aachen, Germany
studies, dissociation of the pyridine ligand in the imido tita-
nium complexes 1–3 is slow up to 100 °C.
The bis(dimethylamido)titanium complex 4 was synthe-
sized under dimethylamine elimination from [Ti(NMe2)4]
and bis(phenol) edtbpH2 in 1:1 molar ratio (Scheme 2) and
isolated as red crystals in 85% yield. The H NMR spec-
trum of 4 in C6D6 shows an AB spin pattern for the
Fax: +49-241-80-92644
E-mail: jun.okuda@ac.rwth-aachen.de
[b] Institut für Organische Chemie, Friedrich-Alexander Uni-
versität Erlangen-Nürnberg,
Henkestr. 42, 91054 Erlangen, Germany
[‡] New address: Rutgers, The State University of New Jersey, De-
partment of Chemistry and Chemical Biology,
610 Taylor Road, Piscataway, NJ 08854-8087, USA
1
Eur. J. Inorg. Chem. 2009, 429–434
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
429

J. Okuda et al.
FULL PAPER
1 and 5 in the solid state as well as selected interatomic
distances and angles are shown in Figure 1 and Figure 2.
Complexes 1 and 5 are monomeric in the solid state.
Scheme 1.
SCH2CH2S bridge (δ = 2.56 and 2.16 ppm) and one singlet
at δ = 3.53 ppm for all 4 methyl groups of the dimeth-
ylamido groups. This is in agreement for the bis(dimethyl-
amido)titanium complex generated in situ.[2l] These NMR
spectra data suggest a C2-symmetric molecular structure in
solution.
Figure 1. Molecular structure of complex [Ti(edtbp)-
(NtBu)(NC5H5)] (1) (hydrogen atoms were omitted for clarity). Se-
lected bond lengths [Å] and angles [°]: Ti–O1, 1.965(2); Ti–O2,
1.985(2); Ti–S1, 2.7853(10); Ti–S2, 2.5826(10); Ti–N1, 2.202(2); Ti–
N2, 1.705(3); N2–C36, 1.442(4); O1–C1, 1.327(3); O1–Ti–O2,
151.96(9); S1–Ti–S2, 80.73(3); N1–Ti–N2, 102.66(11); Ti–N2–C36,
173.6(3); O2–Ti–S1, 79.73(7); O2–Ti–S2, 77.62(6); O2–Ti–N2,
104.14(11); O2–Ti–N1, 91.70(9).
Scheme 2.
Treating Li2(edtbp) with one equiv. of [Ti(NMe2)Cl3] in
toluene gave the chloro dimethylamido complex
[Ti(edtbp)(NMe2)Cl] (5) as red crystals in 81% yield
1
(Scheme 3). In the H NMR spectrum of 5, an ABCD spin
system for the SCH2CH2S bridge was observed with reso-
nances at δ = 2.52 (dt), 2.38 (dt), 2.22 (td), and 1.97 ppm
(td) which correlate in the HMQC 2D NMR spectrum with
two 13C NMR resonances at δ = 37.87 (2.52 and 2.22 ppm)
and 37.80 ppm (2.38 and 1.97 ppm), respectively. One sing-
let at δ = 3.68 ppm was observed for the two equivalent
methyl groups of the dimethylamido group.
Scheme 3.
Figure 2. Molecular structure of complex [Ti(edtbp)(NMe2)Cl] (5)
(hydrogen atoms were omitted for clarity). Only one of the two
crystallographically independent atoms are shown. Selected bond
lengths [Å] and angles [°]: Ti1–O1, 1.887(2); Ti1–O2, 1.8852(19);
Ti1–S1, 2.5997(10); Ti1–S2, 2.7229(9); Ti1–N1, 1.877(3); Ti1–Cl1,
2.3129(10); N1–C31, 1.450(5); N1–C32, 1.441(4); O1–Ti1–O2,
156.64(9); S1–Ti1–S2, 78.31(3); N1–Ti1–Cl1, 103.86(11); C31–N1–
Ti1, 124.9(2); C32–N1–Ti1, 125.9(2); C31–N1–C32, 109.3(3); O1–
X-ray Crystal Structures of 1 and 5
Single crystals of complexes 1 and 5 were obtained from
pentane and have been characterized by X-ray diffraction
analysis. Details of the crystal structure determination are
given in Table 3 (see Exp. Sect.). The molecular studies of Ti1–S1, 77.19(7); O1–Ti1–N1, 97.85(10).
430 Eur. J. Inorg. Chem. 2009, 429–434
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Imido and Amido Ti Complexes for Hydroamination Catalysis
Table 1. Titanium···sulfur distances in [OSSO]-type bis(phenolato) titanium complexes.
Compound
Ti–S1 [Å] (trans group)
Ti–S2 [Å] (trans group)
Ref.
[3b]
[3e]
[3c]
[3g]
[3f]
[3f]
[3f]
[Ti(etbmp)Cl2]
[Ti(edtbp)Me2]
[Ti(edtbp)(CH2Ph)2]
[Ti{(R,R)-(cytbmp)}(OiPr)2]
[Ti(edtbp)MeCl]
[Ti(edtbp)Me{O(iPrO)C=CMe2}]
[Ti(edtbp)Me(OCMe2CMe2CO2iPr)]
[Ti(edtbp)(NtBu)(NC5H5)] (1)
[Ti(edtbp)(NMe2)Cl] (5)
2.647(3) (Cl)
2.647(3) (Cl)
2.8056(7) (Me)
2.8417(7) (Me)
2.7472(7) (η1-CH2Ph)
2.673(4) (OiPr)
2.6756(8) (Cl)
2.7327(14) (Me)
2.7227(8) (Me)
2.5826(10) (NC5H5)
2.5997(10) (Cl)
2.8836(7) (η2-CH2Ph)
2.674(4) (OiPr)
2.6986(8) (Me)
2.6389(15) [O(iPrO)C=CMe2]
2.7156(8) (OCMe2CMe2CO2iPr)
2.7853(10) (NtBu)
2.7229(9) (NMe2)
this work
this work
The octahedrally coordinated titanium center in complex (phenolato) ligand shows higher activity under rather mild
1 is coordinated by two trans-oxygen atoms, two cis-sulfur reaction conditions. However, the activity of catalyst 1 is
donor atoms, and the cis-arranged pyridine and tert-bu- still lower than the known bis(amidinato)titanium catalyst
tylamido ligands (Figure 1). The Ti(edtbp) moiety adopts a [Ti(C6F5C(O)NtBu)2(NMe2)2]
(97%
yield,
25 °C,
C2-symmetric helical framework similar as observed in the 15 min).[7b] The intermolecular hydroamination with this
previous study.[3a] The O1–Ti–O2 [151.96(9)°] bond angle is type of catalyst has been investigated by Doye et al.[2l]
slightly narrower than that of analogous Ti(edtbp) com-
plexes, in the range of 156.7(2) –157.82(10)°,[3] indicating
the formation of a fairly open titanium coordination sphere.
The bond angle of S1–Ti–S2 [80.73(3)°] is slightly wider
than the value of a similar complex [78.37(8)°];[3b] the Ti–S
Scheme 4.
bond length [2.7853(10) Å and 2.5826 (10) Å] in 1 is com-
parable to the values in a reported dichloro complex
[2.647(3) Å].[3b] The Ti–N2 bond length [1.705(3) Å] is
much shorter than the value of a coordinated Ti–N1 bond
[2.202(2) Å] in 1. The bond angle of Ti–N2–C36 [173.6(3)°]
is close to linear and comparable to the reported values,[5]
indicating that NtBu group donates four electrons to the
titanium metal center.
The solid-state structure of dimethylamido complex 5
also features a six-coordinate titanium center with a C2-
symmetric helical Ti(edtbp) fragment (Figure 2). The O1–
Ti–O2 [156.64(9)°] bond angle is close to that of Ti(edtbp)
complexes [156.7(2)–157.82(10)°].[3] The Ti–N1 [1.877(3) Å]
bond length is comparable to the values of similar amido-
titanium complexes [1.862(3)–1.917(5) Å].[6,2k] The nitrogen
atom is trigonal with the sum of angles around N1 atom
close to 360° (calculated: 360.1°), indicating strong π-elec-
tron donation to the Ti center. Notably, the elongated Ti–
S2 [2.7229(9) Å] bond length as compared to that of Ti–
S1[2.5997(10) Å] is caused by the stronger electron-donat-
ing trans-dimethylamido group in the solid state. Detailed
Catalysts 1–3 have been studied in the intramolecular hy-
droamination of aminoalkenes (Scheme 5). Results are
summarized in Table 2. Only trace amounts of desired cycli-
zation product was observed after short reaction times at
150 °C (entries 5 and 7). High conversions (85–94%) are
achieved at prolonged reaction times of 14–22 d (entries 3,
4 and 6). As commonly observed,[1i] the gem-diphenyl acti-
vated[8] substrate 6a reacts faster than the aminoalkene 6b
using the rigid complex 3 with a cydtbp ligand (Table 2,
entry 3 vs. entry 6). However, the opposite is true for the
more flexible edtbp complex 1 (entry 1 vs. entry 4). Al-
though catalysts 1–3 are active in the intramolecular hy-
comparisons of the trans-influence on the Ti–S bond length Scheme 5.
are shown in Table 1.
Table 2. Intramolecular hydroamination of aminoalkenes using cat-
alysts 1–3.[a]
Intramolecular Hydroamination of Aminoalkyne and
Aminoalkene
Entry
Substrate
Complex
Time [d]
% Conv.[b]
1
2
3
4
5
6
7
6a
6a
6a
6b
6b
6b
6c
1
2
3
1
2
3
1
29
23
14
16
20 h
22
61
78
85
92
Ͻ 1
94
Complex 1 was selected for the catalytic study in the in-
tramolecular hydroamination of 5-phenylpent-4-ynylamine
(Scheme 4). By combination of 5 mol-% of catalyst 1 with
substrate in toluene solution at room temperature, over
91% conversion was observed to give the cyclic imine prod-
uct within 23 h. In comparison with the reported activity
of a titanocene catalyst Cp2TiMe2 (98% yield, 110 °C,
21 h
Ͻ 1
[a] Reaction conditions: substrate: 0.2 mmol, catalyst: 0.02 mmol
(10 mol-%), solvent: 0.5 mL [D8]toluene, temperature: 150 °C. [b]
6 h),[7a] the imidotitanium catalyst with a [OSSO]-type bis- Determined by H NMR spectroscopy.
1
Eur. J. Inorg. Chem. 2009, 429–434
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
431

J. Okuda et al.
FULL PAPER
10.1 Hz, 2 H, SCH2), 1.97 [s, 9 H, C(CH3)3], 1.80 [s, 9 H,
C(CH3)3], 1.33 [s, 9 H, C(CH3)3], 1.23 [s, 9 H, C(CH3)3], 1.20 [s, 9
H, NC(CH3)3] ppm. 13C{1H} NMR ([D6]benzene): δ = 168.86 (Ph-
C1), 167.23 (Ph-C1Ј), 150.01 (NC5H5-o-C), 139.73 (Ph-C6), 138.36
(Ph-C6Ј), 138.27 (NC5H5-p-C), 138.08 (Ph-C4), 137.03 (Ph-C4Ј),
128.43 (Ph-C5), 128.31 (Ph-C5Ј), 126.02 (Ph-C3), 126.01 (Ph-C3Ј),
124.10 (NC5H5-m-C), 117.20 (Ph-C2), 116.11 (Ph-C2Ј), 68.28
[NC(CH3)3], 37.84 (SCH2), 36.16 [C(CH3)3], 35.69 [C(CH3)3], 34.53
[C(CH3)3], 34.29 (SCH2), 34.23 [C(CH3)3], 32.04 [NC(CH3)3], 31.85
[C(CH3)3], 31.73 [C(CH3)3], 29.87 [C(CH3)3], 29.76 [C(CH3)3] ppm.
C39H58N2O2S2Ti (698.89): calcd. C 67.02, H 8.36, N 4.01; found C
67.86, H 8.43, N 3.87.
droamination of aminoalkenes, their catalytic activities are
rather low in comparison with titanium catalysts reported
in the literature, e.g. [Ti(NMe2)4] (substrate 6a, 5 mol-%
cat., 92% yield, 24 h, 110 °C).[2e]
Conclusions
We have isolated imido and amido titanium complexes
that contain a tetradentate [OSSO]-type bis(phenolato) li-
gand. The imido complexes were found to be catalytically
active in the intramolecular hydroamination of aminoal-
kynes and aminoalkenes. The moderate catalytic activities
of these imido catalysts were probably caused by the steri-
cally crowded titanium center with the strongly coordinated
pyridine ligand. Further studies will be undertaken to
achieve enantioselective hydroamination reactions[1b,1e,1f,1h]
using optically pure [OSSO]-type group 4 metal cata-
lysts.[3d,3g]
[Ti(edtbp)(NC6H3iPr2-2,6)(NC5H5)] (2): To a solution of [Ti(N-
C6H3iPr2-2,6)Cl2(NC5H5)3] (1.55 g, 2.92 mmol) in THF (20 mL)
was slowly added at –35 °C a solution of Li2(edtbp) in 30 mL of
toluene, generated in situ from edtbpH2 (1.47 g, 2.92 mmol) and
nBuLi (2.34 mL, 2.5  in hexane, 5.85 mmol). The reaction mixture
was warmed to room temperature and further stirred 6 h. After
evaporation of volatile under vacuum, the residue was recrys-
tallized with toluene/pentane to give [Ti(edtbp)(NC6H3iPr2-
1
2,6)(NC5H5)] (2) as brown crystals (1.87 g, 80%). H NMR ([D6]-
3
4
benzene): δ = 9.16 (dt, JHH = 4.6, JHH = 1.7 Hz, 2 H, o-H,
NC5H5), 7.64 (d, 4J = 2.4 Hz, 1 H, Ph-5-H), 7.58 (d, 4JHH = 2.4 Hz,
1 H, Ph-5Ј-H), 7.29 (d, 4JHH = 2.4 Hz, 1 H, Ph-3-H), 7.22 (d, 4JHH
Experimental Section
3
= 2.4 Hz, 1 H, Ph-3Ј-H), 7.03 (d, JHH = 7.9 Hz, 2 H, NAr-3-H),
3
3
4
General: All experiments were carried out under purified argon
using standard Schlenk techniques or a glove box (Ͻ1 ppm O2,
1 ppm H2O). Toluene, pentane, diethyl ether, dichloromethane, and
THF were purified from the MBraun SPS-800 system prior to use.
Deuterated solvents were purchased from Aldrich and purified be-
fore use. All other chemicals were commercially available and used
after appropriate purification. Compounds (HOC6H2-tBu2-4,6)2-
(SCH2CH2S) (edtbpH2),[3a] rac-(2,3-trans-butanediyl-1,4-dithia-
butanediyl)-2,2Ј-bis{4,6-di-tert-butylphenol} [rac-(cydtbp)H2],[3d]
6.85 (t, JHH = 7.9 Hz, 1 H, NAr-4-H), 6.66 (tt, JHH = 7.5, JHH
3
= 1.7 Hz, 1 H, p-H, NC5H5), 6.40 (tm, JHH = 6.4 Hz, 2 H, m-H,
3
NC5H5), 4.49 [sept, JHH = 6.8 Hz, 2 H, (CH3)2CH], 2.60 (dm,
2JHH = 10.1 Hz, 1 H, SCH2), 2.48 (dm, JHH = 10.1 Hz, 1 H,
2
SCH2), 2.24 (td, 2JHH = 13.2, 3JHH = 3.2 Hz, 1 H, SCH2), 2.13 (td,
2JHH = 13.2, JHH = 3.2 Hz, 1 H, SCH2), 1.89 [s, 9 H, C(CH3)3],
3
3
1.71 [s, 9 H, C(CH3)3], 1.32 [s, 9 H, C(CH3)3], 1.23 [d, JHH
6.8 Hz, 6 H, (CH3)2CH], 1.22 [s, 9 H, C(CH3)3], 1.04 [d, JHH
=
=
3
6.8 Hz, 6 H, (CH3)2CH] ppm. 13C{1H} NMR ([D6]benzene): δ =
168.68 (Ph-C1), 166.89 (Ph-C1Ј), 156.92 (NAr-C1), 149.33
(NC5H5-o-C), 143.31 (NAr-C2), 140.92 (Ph-C6), 139.01 (Ph-C6Ј),
138.24 (NC5H5-p-C), 138.17 (Ph-C4), 136.95 (Ph-C4Ј), 127.62 (Ph-
C5), 127.46 (Ph-C5Ј), 126.11 (Ph-C3), 125.85 (Ph-C3Ј), 124.22
(NC5H5-m-C), 121.92 (NAr-C3), 120.78 (NAr-C4), 117.47 (Ph-C2),
117.00 (Ph-C2Ј), 37.74 (SCH2), 35.07 (SCH2), 35.62 [C(CH3)3],
35.25 [C(CH3)3], 33.82 [C(CH3)3], 33.70 [C(CH3)3], 31.47 [C-
(CH3)3], 31.31 [C(CH3)3], 29.56 [C(CH3)3], 29.41 [C(CH3)3], 27.41
[CH(CH3)2], 24.47 [CH(CH3)2], 24.06 [CH(CH3)2] ppm.
C47H66N2O2S2Ti (803.04): calcd. C 70.30, H 8.28, N 3.49; found C
69.63, H 8.58, N 3.42.
[Ti(NtBu)Cl2(NC5H5)3],[5]
[Ti(NC6H3iPr2-2,6)Cl2(NC5H5)3],[5]
[Ti(NMe2)Cl3],[9] 5-phenylpent-4-ynylamine,[10a] 2,2-diphenylpent-
4-enylamine (6a),[10b] C-(1-allylcyclohexyl)methylamine (6b)[10c]
and 2,2-dimethylpent-4-enylamine (6c)[10d] were synthesized ac-
cording to literature methods. NMR spectra were recorded on
Bruker DRX 400 (1H, 400 MHz; 13C, 101 MHz) and Varian 200
spectrometers in Teflon-valved NMR tubes at 25 °C unless stated
otherwise. 1H and 13C NMR chemical shifts were determined using
residual solvent resonances and are reported vs. SiMe4. Assignment
1
1
of signals was made from H-13C HMQC and H-13C HMBC 2D
NMR experiments. Coupling constants are given in Hertz. Elemen-
tal analyses were performed by the Microanalytical Laboratory of
this department.
[Ti{rac-(cydtbp)}(NtBu)(NC5H5)] (3): To a solution of [Ti(NtBu)-
Cl2(NC5H5)3] (0.75 g, 1.76 mmol) in THF (20 mL) was slowly
added at –35 °C a solution of Li2{rac-(cydtbp)} in 30 mL of tolu-
ene, generated in situ from rac-(cydtbp)H2 (0.98 g, 1.76 mmol) and
nBuLi (1.40 mL, 2.5  in hexane, 3.52 mmol). The reaction mixture
was warmed to room temperature and further stirred overnight.
After removal of all volatiles under vacuum, the residue was recrys-
tallized from pentane to give [Ti{rac-(cydtbp)}(NtBu)(NC5H5)] (3)
[Ti(edtbp)(NtBu)(NC5H5)] (1): To
a solution of [Ti(NtBu)-
Cl2(NC5H5)3] (1.25 g, 2.92 mmol) in THF (20 mL) was slowly
added at –35 °C a solution of Li2(edtbp) in 30 mL of toluene, gen-
erated in situ from edtbpH2 (1.47 g, 2.92 mmol) and nBuLi
(2.34 mL, 2.5  in hexane, 5.85 mmol). The reaction mixture was
warmed to room temperature and stirred for 6 h. After removal of
all volatiles under vacuum, the residue was recrystallized from pen-
tane to give [Ti(edtbp)(NtBu)(NC5H5)] (1) as orange crystals
(1.67 g, 82%). A crystal of 1 suitable for X-ray diffraction analysis
1
as yellow crystals (1.15 g, 87%). H NMR ([D6]benzene): δ = 9.34
3
4
4
(dt, JHH = 4.6, JHH = 1.7 Hz, 2 H, o-H, NC5H5), 7.67 (d, JHH
4
= 2.4 Hz, 1 H, Ph-5-H), 7.65 (d, J = 2.4 Hz, 1 H, Ph-5Ј-H), 7.48
3
4
4
was selected. 1H NMR ([D6]benzene): δ = 9.28 (dt, JHH = 4.6,
(d, JHH = 2.4 Hz, 1 H, Ph-3-H), 7.30 (d, JHH = 2.4 Hz, 1 H, Ph-
4JHH = 1.7 Hz, 2 H, o-H, NC5H5), 7.63 (d, JHH = 2.4 Hz, 1 H, 3Ј-H), 6.68 (tt, 3JHH = 7.5, 4JHH = 1.7 Hz, 1 H, p-H, NC5H5), 6.47
4
4
4
Ph-5-H), 7.61 (d, JHH = 2.4 Hz, 1 H, Ph-5Ј-H), 7.43 (d, JHH
=
(tm, 3JHH = 6.4 Hz, 2 H, m-H, NC5H5), 2.47 (td, 2JHH = 13.2, 3JHH
4
2
3
2.4 Hz, 1 H, Ph-3-H), 7.20 (d, JHH = 2.4 Hz, 1 H, Ph-3Ј-H), 6.70
= 3.2 Hz, 1 H, SCH), 2.34 (td, JHH = 13.2, JHH = 3.2 Hz, 1 H,
(tt, JHH = 7.5, JHH = 1.7 Hz, 1 H, p-H, NC5H5), 6.48 (tm, JHH SCH), 2.03 (m, 2 H, cyclohexyl), 2.01 [s, 9 H, C(CH3)3], 1.83 [s, 9
3
4
3
2
= 6.4 Hz, 2 H, m-H, NC5H5), 2.72 (dm, JHH = 10.1 Hz, 1 H,
H, C(CH3)3], 1.68 (m, 2 H, cyclohexyl), 1.38 [s, 9 H, C(CH3)3], 1.28
[s, 9 H, NC(CH3)3], 1.22 [s, 9 H, C(CH3)3], 1.14 (m, 2 H, cyclo-
2
2
SCH2), 2.58 (dm, JHH = 10.1 Hz, 1 H, SCH2), 2.18 (d, JHH
=
432
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 429–434

Imido and Amido Ti Complexes for Hydroamination Catalysis
4
hexyl), 0.43 (m, 2 H, cyclohexyl) ppm. 13C{1H} NMR ([D6]ben- tals (1.03 g, 81%). 1H NMR ([D6]benzene): δ = 7.52 (d, JHH
=
4
zene): δ = 169.11 (Ph-C1), 167.47 (Ph-C1Ј), 150.13 (NC5H5-o-C),
2.2 Hz, 2 H, Ph-5-H), 7.22 (d, JHH = 2.2 Hz, 1 H, Ph-3-H), 7.08
4
138.24 (NC5H5-p-C), 137.92 (Ph-C6), 137.08 (Ph-C6Ј), 130.65 (Ph- (d, JHH = 2.2 Hz, 1 H, Ph-3Ј-H), 3.68 [s, 6 H, N(CH3)2], 2.52 (dt,
C4), 130.61 (Ph-C4Ј), 128.44 (Ph-C5), 128.32 (Ph-C5Ј), 126.27 (Ph- 2JHH = 10.2, JHH = 3.0 Hz, 1 H, SCH2), 2.38 (dt, JHH = 10.2,
3
2
2
3
C3), 126.18 (Ph-C3Ј), 124.04 (NC5H5-m-C), 114.89 (Ph-C2), 114.30
(Ph-C2Ј), 68.07 [NC(CH3)3], 52.68 (SCH), 50.71 (SCH), 36.21
[C(CH3)3], 35.75 [C(CH3)3], 34.08 [C(CH3)3], 34.05 [C(CH3)3],
32.03 [NC(CH3)3], 31.85 [C(CH3)3], 31.74 [C(CH3)3], 30.01 (cyclo-
3JHH = 3.0 Hz, 1 H, SCH2), 2.22 (td, JHH = 10.2, JHH = 3.0 Hz,
2
3
1 H, SCH2), 1.97 (td, JHH = 10.2, JHH = 3.0 Hz, 1 H, SCH2),
1.72 [s, 9 H, C(CH3)3], 1.66 [s, 9 H, C(CH3)3], 1.20 [s, 9 H,
C(CH3)3], 1.19 [s, 9 H, C(CH3)3] ppm. 13C{1H} NMR ([D6]ben-
hexyl), 29.94 [C(CH3)3], 29.85 [C(CH3)3], 29.48 (cyclohexyl), 25.56 zene): δ = 166.55 (Ph-C1), 166.50 (Ph-C1Ј), 143.60 (Ph-C6), 143.15
(cyclohexyl), 25.44 (cyclohexyl) ppm. C43H64N2O2S2Ti (752.98):
calcd. C 68.59, H 8.57, N 3.72; found C 67.92, H 8.60, N 3.41.
(Ph-C6Ј), 138.05 (Ph-C4), 136.20 (Ph-C4Ј), 128.50 (Ph-C5), 128.13
(Ph-C5Ј), 126.33 (Ph-C3), 126.14 (Ph-C3Ј), 120.03 (Ph-C2), 118.93
(Ph-C2Ј), 50.50 [N(CH3)2], 37.87 (SCH2), 37.80 (SCH2), 35.75
[C(CH3)3], 35.64 [C(CH3)3], 34.58 [C(CH3)3], 34.48 [C(CH3)3],
31.62 [C(CH3)3], 31.60 [C(CH3)3], 29.85 [C(CH3)3], 29.80
[C(CH3)3] ppm. C32H50ClNO2S2Ti (628.19): calcd. C 61.18, H 8.02,
N 2.23; found C 61.63, H 7.73, N 2.22.
[Ti(edtbp)(NMe2)2] (4): [Ti(NMe2)4] (0.45 g, 1.99 mmol) and 15 mL
toluene were charged in a 100 mL Schlenk tube and a solution of
edtbpH2 (1.0 g, 1.99 mmol) in 50 mL of toluene was added drop-
wise at –50 °C. The reaction mixture was warmed to room tempera-
ture and further stirred overnight. After removal of all volatiles
under vacuum, the residue was recrystallized from pentane to give
Typical Hydroamination Reaction Procedure: In the glovebox, a Tef-
[Ti(edtbp)(NMe2)2] (4) as red crystals (1.08 g, 85%). 1H NMR lon-valved NMR tube was charged with 5 mol-% or 10 mol-% of
4
([D6]benzene): δ = 7.55 (d, JHH = 2.4 Hz, 2 H, Ph-5-H), 7.25 (d,
the imidotitanium complex (0.01 mmol or 0.02 mmol). Deuterated
toluene (ca. 0.5 mL) was added via syringe. Then, 0.2 mmol of the
4JHH = 2.4 Hz, 2 H, Ph-3-H), 3.53 [s, 12 H, N(CH3)2], 2.56 (d,
2JHH = 12.0 Hz, 2 H, SCH2), 2.16 (d, 2JHH = 12.0 Hz, 2 H, SCH2), substrate was added and the reaction mixture was shaken for a
1.77 [s, 18 H, C(CH3)3], 1.22 [s, 18 H, C(CH3)3] ppm. 13C{1H} moment. The reaction was carried out at 150 °C and NMR spectra
NMR ([D6]benzene): δ = 166.91 (Ph-C1), 140.94 (Ph-C6), 137.17
(Ph-C4), 127.37 (Ph-C5), 125.91 (Ph-C3), 117.01 (Ph-C2), 47.70
[N(CH3)3], 37.12 (SCH2), 35.38 [C(CH3)3], 33.83 [C(CH3)3], 31.32
[C(CH3)3], 29.61 [C(CH3)3] ppm. C34H56N2O2S2Ti (636.82): calcd.
C 64.13, H 8.86, N 4.40; found C 64.54, H 8.70, N 4.08.
were recorded periodically.
Crystal Structure Determination of Complexes 1 and 5: X-ray dif-
fraction measurements were performed on a Bruker AXS dif-
fractometer with Mo-Kα radiation using ω-scans. Crystal param-
eters and result of the structure refinement are given in Table 3.
[Ti(edtbp)(NMe2)Cl] (5): [Ti(NMe2)Cl3] (0.40 g, 2.02 mmol) and Absorption corrections were carried out with the multi-scan
15 mL toluene were charged in a 100 mL Schlenk, and a solution
of Li2(edtbp) in 50 mL of toluene, generated in situ from edtbpH2
(1.02 g, 2.02 mmol) and nBuLi (1.61 mL, 2.5  in hexane,
4.04 mmol), was added dropwise at –50 °C. The reaction mixture
was warmed to room temperature and further stirred overnight.
After evaporation of volatile under vacuum, the residue was recrys-
tallized from pentane to give [Ti(edtbp)(NMe2)Cl] (5) as red crys-
method using SADABS.[11] The structures were solved by direct
and Fourier difference methods (SIR-92)[12a] and refined
(SHELXS-97)[12b] against all F2 data. All non-hydrogen atoms were
refined with anisotropic displacement parameters. Hydrogen atoms
were included into calculated positions. For the graphical represen-
tation, the program ORTEP was used as implemented in the pro-
gram system WinGX.[13]
Table 3. Crystallographic and data collection parameters for 1 and 5.
Compound
1
5
Empirical formula
Mr
Crystal system
Space group
C39H58N2O2S2Ti·C5H12
771.04
monoclinic
P21/c
2 C32H50ClNO2S2Ti·C5H12
1328.55
triclinic
¯
P1
a [Å]
b [Å]
c [Å]
α [°]
18.237(3)
28.490(5)
9.4719(18)
15.5137(11)
15.9150(11)
17.9791(13)
113.213(1)
96.392(1)
108.034(1)
3738.4(5)
2
β [°]
100.459(4)
γ [°]
V [Å3]
4849.1(15)
4
1.056
130(2)
0.295
Z
Dcalcd. [g·cm–3]
1.180
110(2)
0.441
T [K]
µ(Mo-Kα) [mm–1]
F(000)
θ Range [°]
Number of reflections collected
Number of reflections observed [I Ͼ 2σ(I)]
1672
2.27–28.34
66138
1428
2.31–25.54
42238
8736
10962
Number of independent reflections (Rint
Data / restraints / parameters
Goodness-of-fit on F2
)
12100 (0.0575)
12100 / 0 / 474
1.054
0.0725, 0.1995
0.1009, 0.2191
1.757 and –0.431
13971 (0.0464)
13971 / 0 / 778
1.033
0.0549, 0.1373
0.0720, 0.1486
1.463 and –1.009
R1, wR2 [I Ͼ 2σ(I)]
R1, wR2 (all data)
Largest difference in peak and hole [e·Å–3]
Eur. J. Inorg. Chem. 2009, 429–434
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
433

J. Okuda et al.
FULL PAPER
25, 3019–3026; d) K. Beckerle, R. Manivannan, B. Lian, G.-
J. M. Meppelder, G. Raabe, T. P. Spaniol, H. Ebeling, F. Pelas-
cini, R. Mülhaupt, J. Okuda, Angew. Chem. Int. Ed. 2007, 46,
4790–4793; e) B. Lian, K. Beckerle, T. P. Spaniol, J. Okuda,
Angew. Chem. Int. Ed. 2007, 46, 8507–8510; f) B. Lian, T. P.
Spaniol, J. Okuda, Organometallics 2007, 26, 6653–6660; g) G.-
J. M. Meppelder, K. Beckerle, R. Manivannan, B. Lian, G.
Raabe, T. P. Spaniol, J. Okuda, Chem. Asian J. 2008, 3, 1312–
1323.
CCDC-704368 (for 1) and -704369 (for 5) contain the supplemen-
tary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
We thank the Deutsche Forschungsgemeinschaft (DFG) and the
Fonds der Chemischen Industrie for financial support. K. C. H.
was a DFG Emmy Noether fellow (2001–2007). We are also grate-
ful to Mr. Y.-T. Wang for collecting crystallographic data and to
Prof. U. Englert for helpful discussions.
[4] a) C. Capacchione, A. Proto, V. Venditto, J. Okuda, Macromol-
ecules 2003, 36, 9249–9251; b) C. Capacchione, M. DЈAcunzi,
O. Motta, L. Oliva, A. Proto, J. Okuda, Macromol. Chem.
Phys. 2004, 205, 370–373; c) C. Capacchione, A. Proto, J.
Okuda, J. Polym. Sci., Part A: Polym. Chem. 2004, 42, 2815–
2822; d) C. Capacchione, F. De Carlo, C. Zannoni, J. Okuda,
A. Proto, Macromolecules 2004, 37, 8918–8922; e) C. Capac-
chione, A. Proto, H. Ebeling, R. Mülhaupt, J. Okuda, J. Polym.
Sci., Part A: Polym. Chem. 2006, 44, 1908–1913; f) C. Capac-
chione, A. Avagliano, A. Proto, Macromolecules 2008, 41,
4573–4575; g) B. T. Gall, F. Pelascini, H. Ebeling, K. Beckerle,
J. Okuda, R. Mülhaupt, Macromolecules 2008, 41, 1627–1633.
[5] A. J. Blake, P. E. Collier, S. C. Dunn, W.-S. Li, P. Mountford,
O. V. Shishkin, J. Chem. Soc., Dalton Trans. 1997, 1549–1558.
[6] a) A. R. Johnson, W. M. Davis, C. C. Cummins, Organometal-
lics 1996, 15, 3825–3835; b) R. Kempe, P. Arndt, Inorg. Chem.
1996, 35, 2644–2649; c) H. Fuhrmann, S. Brenner, P. Arndt,
R. Kempe, Inorg. Chem. 1996, 35, 6742–6745; d) L. T. Ar-
mistead, P. S. White, M. R. Gagné, Organometallics 1998, 17,
216–220; e) M. R. Mason, B. N. Fneich, K. Kirschbaum, Inorg.
Chem. 2003, 42, 6592–6594.
[7] a) I. Bytschkov, S. Doye, Tetrahedron Lett. 2002, 43, 3715–
3718; b) C. Li, R. K. Thomson, B. Gillon, B. O. Patrick, L. L.
Schafer, Chem. Commun. 2003, 2462–2463.
[8] For a review on the gem-dialkyl effect see: M. E. Jung, G. Pizzi,
Chem. Rev. 2005, 105, 1735–1766.
[9] E. Benzing, W. Kornicker, Chem. Ber. 1961, 94, 2263–2267.
[10] a) Y. Li, T. J. Marks, J. Am. Chem. Soc. 1996, 118, 9295–9306;
b) S. Hong, S. Tian, M. V. Metz, T. J. Marks, J. Am. Chem. Soc.
2003, 125, 14768–14783; c) C. F. Bender, R. A. Widenhoefer, J.
Am. Chem. Soc. 2005, 127, 1070–1071; d) Y. Tamaru, M. Hojo,
H. Higashimura, Z.-I. Yoshida, J. Am. Chem. Soc. 1988, 110,
3994–4002.
[1] a) F. Pohlki, S. Doye, Chem. Soc. Rev. 2003, 32, 104–114; b)
P. W. Roesky, T. E. Müller, Angew. Chem. Int. Ed. 2003, 42,
2708–2710; c) J. F. Hartwig, Pure Appl. Chem. 2004, 76, 507–
516; d) S. Hong, T. J. Marks, Acc. Chem. Res. 2004, 37, 673–
686; e) K. C. Hultzsch, Adv. Synth. Catal. 2005, 347, 367–391;
f) K. C. Hultzsch, Org. Biomol. Chem. 2005, 3, 1819–1824; g)
F. Pohlki, S. Doye, Chem. Soc. Rev. 2007, 36, 1407–1420; h) I.
Aillaud, J. Collin, J. Hannedouche, E. Schulz, Dalton Trans.
2007, 5105–5118; i) T. E. Müller, K. C. Hultzsch, M. Yus, F.
Foubelo, M. Tada, Chem. Rev. 2008, 108, 3795–3892.
[2] a) L. Ackermann, L. T. Kaspar, C. J. Gschrei, Org. Lett. 2004,
6, 2515–2518; b) D. V. Gribkov, K. C. Hultzsch, Angew. Chem.
Int. Ed. 2004, 43, 5542–5546; c) P. D. Knight, I. Munslow, P. N.
O’Shaughnessy, P. Scott, Chem. Commun. 2004, 894–895; d) H.
Kim, P. H. Lee, T. Livinghouse, Chem. Commun. 2005, 5205–
5207; e) J. A. Bexrud, J. D. Beard, D. C. Leitch, L. L. Schafer,
Org. Lett. 2005, 7, 1959–1962; f) D. A. Watson, M. Chiu, R. G.
Bergman, Organometallics 2006, 25, 4731–4733; g) A. V. Lee,
L. L. Schafer, Organometallics 2006, 25, 5249–5254; h) H. Kim,
Y. K. Kim, J. H. Shim, M. Kim, M. Han, T. Livinghouse, P. H.
Lee, Adv. Synth. Catal. 2006, 348, 2609–2618; i) B. D. Stubbert,
T. J. Marks, J. Am. Chem. Soc. 2007, 129, 6149–6167; j) M. C.
Wood, D. C. Leitch, C. S. Yeung, J. A. Kozak, L. L. Schafer,
Angew. Chem. Int. Ed. 2007, 46, 354–358; k) J. A. Bexrud, C.
Li, L. L. Schafer, Organometallics 2007, 26, 6366–6372; l) K.
Marcseková, C. Loos, F. Rominger, S. Doye, Synlett 2007,
2564–2568; m) S. Majumder, A. L. Odom, Organometallics [11] Siemens, ASTRO, SAINT and SADABS. Data Collection and
2008, 27, 1174–1177; n) K. Gräbe, F. Pohlki, S. Doye, Eur. J.
Org. Chem. 2008, 4815–4823; o) C. Müller, W. Saak, S. Doye,
Eur. J. Org. Chem. 2008, 2731–2739.
Processing Software for the SMART System, Siemens Analyti-
cal X-ray Instruments Inc., Madison, Wisconsin, USA, 1996.
[12] a) A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi,
J. Appl. Crystallogr. 1993, 26, 343–350; b) G. M. Sheldrick,
SHELXL-97, A Program for Crystal Structure Refinement,
University of Göttingen, Germany, 1997.
[3] a) C. Capacchione, A. Proto, H. Ebeling, R. Mülhaupt, K.
Möller, T. P. Spaniol, J. Okuda, J. Am. Chem. Soc. 2003, 125,
4964–4965; b) C. Capacchione, R. Manivannan, M. Barone, K.
Beckerle, R. Centore, L. Oliva, A. Proto, A. Tuzi, T. P. Spaniol,
J. Okuda, Organometallics 2005, 24, 2971–2982; c) K. Beckerle,
R. Manivannan, T. P. Spaniol, J. Okuda, Organometallics 2006,
[13] L. J. Farrugia, J. Appl. Crystallogr. 1999, 32, 837.
Received: October 6, 2008
Published Online: December 15, 2008
434
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 429–434