DOI: 10.1002chem.200903017 [631872]

DOI: 10.1002/chem.200903017
Direct Synthesis of Titanium Complexes with Chelating cis-9,10-
Dihydrophenanthrenediamide Ligands through Sequential C /C0C Bond-
Forming Reactions from o-Metalated Arylimines
Dapeng Zhao, Wei Gao, Ying Mu,* and Ling Ye[a]
Introduction
Carbon–carbon bond-forming reactions have been one of
the most active research areas in organic and organometallic
chemistry.[1]In particular, transition-metal-mediated carbon–
carbon bond-forming reactions have been studied extensive-ly for construction of the basic carbon backbone of small or-ganic molecules and extended polymeric structures.
[2]Mech-
anistic studies of such reactions indicate that the stoichio-metric and catalytic C /C0C bond-forming reactions mediated
by mid- and late-transition metals can follow several path-
ways, such as reductive elimination, oxidative coupling, mi-
gratory insertion, and s-bond or p-bond metathesis,
[3]
whereas reactions mediated by Group 4 metals go mainly
through the migratory insertion pathway, which does not re-quire redox changes at the metal centre such as those thathappen in Ziegler–Natta polymerisation reactions.
[4]The
Group 4 metals also mediate C /C0C bond-forming reactionsthrough the reductive elimination process, although the cou-
pling of alkyl, acyl, and 1-alkenyl groups is the most com-monly observed C /C0C bond-forming reductive elimination
involving Group 4 metal complexes.
[5]Very few examples of
aryl–aryl bond-forming reductive eliminations mediated byGroup 4 metals have been reported so far,
[6]although the
analogous process is well documented for Group 10metals.
[7]Yet the oxidative coupling of unsaturated organic
compounds to low-valent Group 4 metals is an efficientpathway for construction of carbon–carbon bonds.
[8]In oxi-
dative coupling reactions, the compounds of low-valent
Group 4 metals such as TiIIor ZrIIare usually generated by
treatment of TiIVor ZrIVcomplexes with Grignard or orga-
nolithium reagents, followed by a reductive elimination pro-cess.
[9]In principle, both the reductive elimination and oxi-
dative coupling processes can be used to construct carbon–carbon bonds. However, there are no examples of formationof two C /C0C bonds in one molecule by means of the sequen-
tial reductive elimination and oxidative coupling reactions.
Recently, in an attempt to synthesise [{ o-C
6H4 ACHTUNGTRENNUNG(CH=
NR)}2TiCl2] complexes as potential olefin polymerisation
catalysts, some new titanium complexes with a cis-9,10-dihy-
drophenanthrenediamide ligand were obtained in highyields. Clearly the latter complexes are produced throughsequential C /C0C bond-forming reductive elimination and oxi-
dative coupling from the originally formed [{ o-C
6H4 ACHTUNGTRENNUNG(CH=Abstract: A series of new titanium(IV)
complexes with o-metalated arylimine
and/or cis-9,10-dihydrophenanthrene-
diamide ligands, [ o-C6H4 ACHTUNGTRENNUNG(CH=
NR)TiCl3]( R=2,6-iPr2C6H3(3a), 2,6-
Me2C6H3(3b),tBu ( 3c)), [ cis-9,10-
PhenH2(NR)2TiCl2] (PhenH2=9,10-di-
hydrophenanthrene; R =2,6-iPr2C6H3
(4a), 2,6-Me2C6H3(4b),tBu ( 4c)),
[{cis-9,10-PhenH2(NR)2} ACHTUNGTRENNUNG{o-C6H4 ACHTUNGTRENNUNG(HC=
NR)}TiCl] (R =2,6-iPr2C6H3(5a), 2,6-
Me2C6H3(5b),tBu ( 5c)), have beensynthesised from the reactions of TiCl4
with o-C6H4 ACHTUNGTRENNUNG(CH=NR)Li (R =2,6-
iPr2C6H3, 2,6-Me2C6H3,tBu). Com-
plexes 4and5were formed unexpect-
edly from the reactions of TiCl4with
two or three equivalents of the corre-
sponding o-C6H4 ACHTUNGTRENNUNG(CH=NR)Li followedby sequential intramolecular C /C0C
bond-forming reductive eliminationand oxidative coupling reactions. At-tempts to isolate the intermediates, [{ o-
C
6H4 ACHTUNGTRENNUNG(CH=NR)}2TiCl2](2), were unsuc-
cessful. All complexes were character-
ised by1H and13C NMR spectroscopy,
and the molecular structures of 3a,4a–
c,5a, and 5cwere determined by X-
ray crystallography.Keywords: C/C0C coupling ·di-
amines ·domino reactions ·synthet-
ic methods ·titanium
[a] Dr. D. Zhao, Dr. W. Gao, Prof. Y. Mu, L. Ye
State Key Laboratory of Supramolecular Structure and Materials
School of Chemistry, Jilin UniversityChang Chun 130012 (China)Fax : (
+86)431-85193421
E-mail: ymu@jlu.edu.cn
/C23 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 2010,16, 4394 – 4401 4394

NR)}2TiCl2]. To the best of our knowledge, this is the first
time that such a sequential C /C0C bond-forming process has
been used to synthesise complexes of this type. The new
chemistry may supply a simple and efficient method of syn-
thesizing complexes with various diamide ligands directlyfrom easily obtained imine compounds. The rare titanium-mediated aryl–aryl bond-forming reductive elimination in-volved in the process makes this chemistry especially inter-esting.
Herein we report the synthesis of the new titanium(IV)
complexes with o-metalated arylimine and/or cis-9,10-dihy-
drophenanthrenediamide ligands, [ o-C
6H4 ACHTUNGTRENNUNG(CH=NR)TiCl3]
(R=2,6-iPr2C6H3(3a), 2,6-Me2C6H3(3b),tBu ( 3c)), [cis-
9,10-PhenH2(NR)2TiCl2] (PhenH2=9,10-dihydrophenan-
threne; R =2,6-iPr2C6H3(4a), 2,6-Me2C6H3(4b),tBu ( 4c)),
[{cis-9,10-PhenH2(NR)2} ACHTUNGTRENNUNG{o-C6H4 ACHTUNGTRENNUNG(CH=NR)}TiCl] (R =2,6-
iPr2C6H3(5a), 2,6-Me2C6H3(5b),tBu ( 5c)), and the at-
tempted synthesis of intermediate complexes [{ o-C6H4 ACHTUNGTRENNUNG(CH=
NR)}2TiCl2](2) from the reaction of TiCl4with o-C6H4Li-
ACHTUNGTRENNUNG(CH=NR) (R =2,6-iPr2C6H3, 2,6-Me2C6H3,tBu), as well as
their spectroscopic characterisation and crystal structureanalysis of complexes 3a,4a–c,5a, and 5c.
Results and Discussion
Synthesis of imine compounds : The imine compounds o-
C6H4 ACHTUNGTRENNUNG(CH=NR)Br ( 1a–c) were prepared according to a liter-
ature procedure[10]in high yields by condensation of o-bro-
mobenzaldehyde with the corresponding amine (1 equiv) inhexane (Scheme 1). Compound 1awas isolated as yellow
crystals, whereas 1band 1cwere obtained as pale yellow
oils. These compounds are soluble in most common organicsolvents. Compounds 1a–cwere characterised by
1H and
13C NMR spectroscopy and elemental analysis. Their
1H NMR spectra exhibit resonances in the region of d=
8.58–8.64 ppm for the C H=Nimine protons, with the corre-
sponding13C NMR resonances occurring in the range d=
154.5–162.0 ppm.Reaction of TiCl4with o-C6H4 ACHTUNGTRENNUNG(CH=NR)Li : Reactions of the
o-bromoimine compounds 1a–cwith nBuLi (1 equiv) in
hexane resulted in formation of the corresponding o-lithiat-
ed imine derivatives.[11]The reactions were carried out at
08C to minimise the formation of by-products, as the lithia-
tion reactions are usually rapid and exothermic. The prod-ucts were isolated in high yields as air- and moisture-sensi-tive precipitates, which were washed with hexanes toremove residual nBuLi. In toluene, the o-lithiated imine de-
rivative from 1bhas good solubility whereas those from 1a
and1care sparingly soluble. Reactions of these derivatives
with TiCl
4were studied in detail (Scheme 1): TiCl4with one
equivalent of any of the o-lithiated imine reagents in tolu-
ene gives the corresponding complex 3in high yields (ca.
85%). However, attempts to synthesise complexes 2by the
reactions of TiCl4with two equivalents of a corresponding
o-lithiated imine reagent were unsuccessful. Surprisingly,
when reactions were investigated in different solvents, such
as toluene, diethyl ether, and THF, at different tempera-
tures, unexpected complexes 4with a cis-9,10-dihydrophe-
nanthrenediamide ligand were always isolated instead of 2.
To our knowledge, no similar chemistry has been reportedfor Group 4 metals. Ti
IVand ZrIVcomplexes with two o-
metalated acetophenone imine ligands (see Scheme 2) simi-
lar to 2were reported recently.[12]These complexes were
found to be stable even when heated to 60 8C in solution
and no reductive eliminationor oxidative coupling C /C0C
bond-forming process was ob-
served. Why complexes 2
could not be isolated from ourreaction system is not veryclear. It is possible that the lessbulky ligands used in our reac-tion system facilitate the re-ductive elimination and oxida-tive coupling C /C0C bond-form-
ing processes. It was found that
the synthetic yields of com-plexes 4a–c(50–70%) depend
on reaction conditions and thesolvent system, and the yieldfor a specific complex decreas-es with the solvent in the order
Scheme 1. Synthesis of complexes 1,3,4, and 5.
Scheme 2. TiIVand ZrIVcomplexes with two o-metalated acetophenone
imine ligands similar to 2.
Chem. Eur. J. 2010,16, 4394 – 4401 /C23 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org 4395FULL PAPER

toluene >diethyl ether >THF. To examine if the initial C /C0C
coupling reaction is caused by light, the reactions were alsotested in the dark; complexes 4were obtained in similar
yields, indicating that the C /C0C coupling process is not a pho-
tochemical reaction. From reactions at molar ratio TiCl
4/o-
lithiated imine =1:3, complexes 5aand5cwere isolated in
high yields ( >85%), but 5bcould be obtained only in low
yields as an oily crude product. Attempts to synthesise tita-nium complexes with two 9,10-dihydrophenanthrenediamideligands by treating TiCl
4with four or more equivalents of an
o-lithiated imine reagent were not successful, and complexes
5were always obtained. Complexes 5could also be formed
in the reactions of TiCl4with two equivalents of an o-lithiat-
ed imine if the reaction conditions (temperature and con-centration) were not properly controlled. Crystallographicanalysis of complexes 4a–c,5a, and 5cindicates that the
9,10-dihydrophenanthrenediamide ligands in these com-plexes are all in a cisconfiguration.
Complexes 3,4and5are all soluble in toluene, CH
2Cl2,
and THF, but less soluble in petroleum ether and hexanes.
Complexes 3are air- and moisture-sensitive in both the
solid state and solution, whereas complexes 4and 5show
relatively good stability to air and moisture, and can be ex-posed to air for several hours without obvious decomposi-tion. Complexes 3,4and 5show good thermal stability in
solution and can be heated in boiling toluene for hours with-out decomposition. Complexes 3,4, and 5were all charac-
terised by elemental analysis and
1H and13C NMR spectros-
copy, and satisfactory analytical results were obtained.
Crystal structures : Crystals of 3a,4a–c,5a, and 5csuitable
for X-ray crystal structure determination were grown fromCH
2Cl2/n-hexane at room temperature. The ORTEP draw-
ings of their molecular structures are shown in Figure 1, and
selected bond lengths and angles are given in Table 1. TheX-ray diffraction analysis reveals that the solid-state struc-ture of 3ahas a C
ssymmetry and adopts a distorted trigonal
bipyramidal geometry around the metal centre with twochlorine atoms and one carbon atom on the equator and theother chlorine atom and the nitrogen atom in the apical po-sitions (Figure 1a; Table 1). The average Ti /C0Cl bond length
(2.214 /C138) is close to those reported in the literature.
[13,2b]
The Ti/C0C (2.109(2) /C138) and Ti /C0N ACHTUNGTRENNUNG(imine) bond lengths (2.255
(18) /C138) are comparable to those reported for related titani-um complexes.
[14]
In the molecular structures of 4aand 4c, the titanium
atom is four-coordinate and the geometry around it can bedescribed as a distorted tetrahedron. Complex 4bexists in a
dimeric form in the solid state, in which titanium atom is
five-coordinate and adopts a distorted trigonal bipyramidal
geometry. The average Ti /C0N bond lengths (1.853 /C138 in 4a,
1.888 /C138 in 4b, and 1.861 /C138 in 4c) are all in normal range
found in other titanium complexes with a diamide li-gand.
[15,2b]The Ti /C0N bond lengths in 4bare longer than
those in 4aand 4cbecause the dimeric structure of 4b
makes the molecule more crowded. The average Ti /C0Cl bondlengths of 2.231 /C138 in 4aand 2.276 /C138 in 4care comparable
to those reported for related titanium chloride complex-es.
[15,2b]The terminal Ti /C0Cl bond length (2.277 (2) /C138) in 4b
is similar to those in 4aand4c, whereas the bridged Ti /C0Cl
bond lengths (2.3946(16) and 2.6059(16) /C138) in 4bare much
longer than normal ones. Because of the dimeric structureof4b, the bond angles of N1-Ti-N2 in 4a(88.08(19)
8) and
4c(90.21(9) 8) are larger than that (85.60(17) 8)i n 4b.F o r
the same reason, the Cl1-Ti-Cl2 bond angles in 4a
(108.56(9) 8) and 4c(113.55(4) 8) are also quite different
from those in 4b(78.11 (5), 86.37 (6), and 127.67(7) 8). The
N1-C1-C14-N2 torsion angle in 4c(50.4(2) 8) is clearly larger
than the corresponding ones in 4a(36.3(5) 8) and 4b
(39.66(2) 8). Similarly, the C2-C7-C8-C13 torsion angle in 4c
(23.0 (4) 8) is also larger than those in 4a(20.1(9) 8) and 4b
(18.25(4) 8). These results reveal that the two tBu groups in
4cimpose a greater effect on forcing the molecule to twist
than the 2,6-diisopropylphenyl and 2,6-dimethylphenylgroups in 4aand4b. These torsion-angle data agree with
1H
and13C NMR analyses of these complexes, indicating that
the bulky tBu groups in 4cblock the transformation be-
tween two different conformations in solution.
In complexes 5aand 5cthe metal centre is five-coordi-
nate, adopting a distorted square pyramidal geometry. Theaverage Ti /C0N ACHTUNGTRENNUNG(amide) bond lengths (1.900 /C138 in 5aand
1.906 /C138 in 5c) are in the normal range found in other titani-
um complexes with a diamide ligand.
[2b,15]The Ti /C0N ACHTUNGTRENNUNG(imine)
bond lengths (2.447(3) /C138 in 5aand 2.3806(17) /C138 in 5c) are
close to those in related titanium complexes with imine li-gands reported in the literature.
[14b]The Ti/C0Cl bond lengths
(2.3218(13) /C138 in 5aand 2.3682(8) /C138 in 5c) and Ti /C0C bond
lengths (2.178 (4) /C138 in 5aand 2.144 (2) /C138 in 5c) are compa-
rable to those reported for related titanium complexes, andlonger than the corresponding ones in 3aand4a–c. As dis-
cussed above for 4aand 4c, the torsion angles of N1-C1-
C14-N2 (53.88(2)
8) and C2-C7-C8-C13 (23.41(4) 8)i n5care
clearly larger than the corresponding ones in 5a(27.9(4) 8
and 18.6(6) 8) due to the relatively large steric effect of tBu
groups in 5c.
NMR analysis of complexes : All new complexes were char-
acterised by1H and13C NMR spectroscopy; for selected
NMR data, see Table 3. For complexes 3a–c, the resonances
for the C H=N protons ( d=8.28–8.40 ppm) in the1H NMR
spectra shift 0.23–0.31 ppm toward high field compared totheir corresponding signals in free imine compounds, whilethe resonances ( d=169.5–179.0 ppm) for the CH=N carbon
atoms in the
13C NMR spectra shift to low field compared
with their corresponding signals in free imine compounds.[16]
Resonances for other protons and carbon atoms are innormal positions. Complexes 4a–ccould be identified readi-
ly by
1H and13C NMR spectroscopy. A sharp singlet was ob-
served at d=6.18 and 6.39 ppm in the1H NMR spectra of
complexes 4aand 4b, respectively, which is representative
of the /C0CHN/C0protons in the 9,10-dihydrophenanthrene
ring. The corresponding /C0CHN/C0carbon resonances were
www.chemeurj.org /C23 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 2010,16, 4394 – 4401 4396
Y. Mu et al.

observed at d=72.6 and 71.5 ppm in their13C NMR spectra.
Two sets of doublets (at d=4.95 and 6.05 ppm) in the
1H NMR spectrum of complex 4cand two resonances (at
d=66.1 and 68.9 ppm) in its13C NMR spectrum were ob-served, indicating that the two /C0CHN/C0groups in the 9,10-
dihydrophenanthrene ring of 4care inequivalent, probably
because the bulky tBu groups at the N atoms block the con-
formation transformation of the six-membered ring. Com-
Figure 1. Perspective view of complexes 3a(a),4a(b),4b(c),4c(d),5a(e), and 5c(f) with thermal ellipsoids drawn at 30% probability level. Hydro-
gen atoms are omitted for clarity. See Table 2 for a summary of the crystallographic data.
Chem. Eur. J. 2010,16, 4394 – 4401 /C23 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org 4397FULL PAPERSynthesis of Titanium Complexes

plexes 5aand5ccould also be readily identified by1H and
13C NMR spectroscopy. The presence of resonances for both
the/C0CHN/C0protons and the C H=N protons in their
1H NMR spectra confirms the structures of 5aand 5c.[17]
The resonance for the C H=N proton in complex 5a(d=
7.92 ppm) shifts 0.36 ppm toward high field compared to thecorresponding signal in complex 3a, while the resonance for
the/C0CHN/C0protons in complex 5a(d=6.06 ppm) shifts0.12 ppm toward high field compared to the corresponding
signal in complex 4a. The resonances for the CH=N and
/C0CHN/C0carbon atoms in complexes 5aall shift toward high
field compared to the corresponding signals in complexes 3a
and 4a. As observed for complex 4c, two sets of doublets
(d=4.68 and 6.53 ppm) were observed for the /C0CHN/C0pro-
tons in complex 5cfor the same reason. For complexes 3a,
4aand5a, two sets of doublets were observed for the twoTable 1. Selected bond lengths [/C138] and angles [ 8] for 3a,4a–c,5a, and 5c.
3a 4a 4b 4c 5a 5c
Ti/C0Cl 2.203(9)–2.233(8) 2.228(2)–2.233(2) 2.277(2)–2.6059(16) 2.2762(9) 2.3218(13) 2.3682(8)
Ti/C0C 2.109(2) – – – 2.178(4) 2.144(2)
Ti/C0N 2.255(18) (imine) 1.842(4),
1.864(4) (amide)1.875(4),
1.901(4) (amide)1.852(2),
1.870(2) (amide)1.882(3),
1.919(3) (amide);2.447(3) (imine)1.8963(16),
1.9168(16) (amide);2.3806(17) (imine)
N-Ti-N – 88.08(19) 85.60(17) 90.21(9) 83.33(15)–157.10(13) 88.68(7)–164.74(6)
Cl-Ti-Cl 90.37(7)–118.94(4) 108.56(9) 78.11(5)–127.67(7) 113.55(4) – –N-C-C-N – 36.3(5) 39.66(2) 50.4(2) 27.9(4) 48.27(4)C2-C7-C8-C13 – 20.1(9) 18.25(4) 23.0(4) 18.6(6) 23.41(4)
C2-C1-C14-C13 – 40.1(6) 44.33(2) 56.2(3) 29.7(4) 53.88(2)
Table 2. Summary of crystallographic data for complexes 3a,4a–c,5aand5c.
3a 4a 4b 4c 5a 5c
formula C19H22Cl3NTi C38H38Cl2N2Ti·0.5C5H12 C33H35Cl2N2Ti C22H28Cl2N2Ti C57H66ClN3Ti·0.5CH2Cl2 C33H42ClN3Ti
Fw 418.63 683.63 578.43 439.24 918.94 564.05
crystal system monoclinic monoclinic triclinic triclinic monoclinic monoclinicspace group P21/nC 2/cP 1¯ P1¯ Cc Cc
a[/C138] 9.6194(8) 19.139(6) 10.287(2) 8.3734(7) 13.075(4) 10.532(3)
b[/C138] 14.0367(11) 17.273(6) 12.568(3) 10.2708(9) 20.681(7) 19.111(5)
c[/C138] 15.6617(12) 23.121(5) 13.028(3) 13.9754(12) 19.572(5) 15.133(4)
a[
8] 90 90 68.23(3) 99.8470(10) 90 90
b[8] 99.2860(10) 91.48(3) 82.22(3) 101.9480(10) 97.583(11) 96.254(4)
g[8] 90 90 83.11(3) 105.4350(10) 90 90
V[/C1383] 2087.0(3) 7641(4) 1545.4(5) 1100.39(16) 5246(3) 3027.8(15)
Z 48 2 2 4 4
m[mm/C01] 0.795 0.392 0.473 0.641 0.303 0.397
Rint 0.0160 0.1227 0.0633 0.0178 0.0415 0.0148
GOOF 1.041 1.016 1.089 1.030 1.027 1.059R1 0.0431 0.1005 0.1030 0.0617 0.0734 0.0295
wR2 0.1163 0.2299 0.2869 0.1166 0.2008 0.0728
Table 3. Selected1H NMR data for complexes 3a–c,4a–c, and 5a–c.[a]
3a 3b 3c 4a 4b 4c 5a 5b 5c
/C0CH=N/C0 8.28
ACHTUNGTRENNUNG(s, 1H)8.40
ACHTUNGTRENNUNG(s, 1H)8.37
ACHTUNGTRENNUNG(s, 1H)– – – 7.92
ACHTUNGTRENNUNG(s, 2H)8.43
ACHTUNGTRENNUNG(s, 1H)
/C0CHN/C0 – – – 6.18
ACHTUNGTRENNUNG(s, 2H)6.39
ACHTUNGTRENNUNG(s, 2H)4.95 (d,3J=
3.9 Hz, 1H);
6.05 (d,3J=
3.9 Hz, 1H)6.06
ACHTUNGTRENNUNG(s, 1H)6.17
ACHTUNGTRENNUNG(s, 2H)4.68 (d,3J=
4.2 Hz, 1H);
6.53 (d,3J=
4.2 Hz, 1H)
/C0CH3 1.12 (d,3J=
6.6 Hz, 6H);
1.34 (d,3J=
6.6 Hz, 6H)2.58
ACHTUNGTRENNUNG(s, 6H)1.67
ACHTUNGTRENNUNG(s, 9H)1.11 (d,3J=
6.6 Hz, 12H);
1.20 (d,3J=
6.6 Hz, 12H)2.42
ACHTUNGTRENNUNG(s, 12H)1.09 (s, 9H);
1.61 (s, 9H)0.44 (d,3J=6.6 Hz, 6H);
0.52 (d,3J=6.6 Hz, 6H);
0.70 (d,3J=6.6 Hz, 6H);
0.90 (d,3J=6.6 Hz, 6H);
1.28 (d,3J=6.6 Hz, 6H);
1.50 (d,3J=6.6 Hz, 6H)2.19
ACHTUNGTRENNUNG(s, 12H);
2.60
ACHTUNGTRENNUNG(s, 6H)1.17
ACHTUNGTRENNUNG(s, 9H);
1.43
ACHTUNGTRENNUNG(s, 9H);
1.75
ACHTUNGTRENNUNG(s, 9H)
/C0CH ACHTUNGTRENNUNG(CH3)23.52 (sept,3J=
6.6 Hz, 2H)– – 3.29 (sept,3J=
6.6 Hz, 4H)– – 2.27 (sept,3J=6.6 Hz, 2H);
3.37 (sept,3J=6.6 Hz, 2H);
3.65 (sept,3J=6.6 Hz, 2H)––
[a]dvalues in ppm referred to TMS; measurements were carried out at room temperature.
www.chemeurj.org /C23 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 2010,16, 4394 – 4401 4398
Y. Mu et al.

methyl groups in the isopropyl unit, indicating that the rota-
tion about the N-aryl bond is blocked in these complexes,
which results in inequivalence of the two methyl groups.
Mechanistic aspects of the coupling reactions : As mentioned
above, complexes 4were always obtained instead of 2from
the reactions of TiCl4with two equivalents of the corre-
sponding o-lithiated imine reagents. On the basis of the
known chemistry and the structure of complexes 4, it can
reasonably be speculated that the complexes 2must be
formed first in these reactions and then converted to com-
plexes 4in situ through the sequential C /C0C bond-forming
reductive elimination and oxidative coupling reactionsshown in Scheme 3. Although the Ti
IVcomplexes 2were not
isolated from our reactions, probably because of their low
stability, similar TiIVand ZrIVcomplexes with two o-metalat-
ed acetophenone imine ligands (Scheme 2) have been ob-tained previously from the reaction of TiCl
4or ZrCl4with
two equivalents of bulky o-lithiated acetophenone imine
ligand, and the crystal structure of the ZrIVcomplex has
been determined.[12]Only a few examples of the TiIV-mediat-
ed aryl–aryl bond-forming reductive elimination have been
reported so far.[6,18]One is the formation of biphenyl and
[(C6H5)2TiII] from [(C6H5)4Ti].[18]Another related example is
the formation of [Cp2TiII(2,2’-biquinoline)] from [Cp2TiIV(2-
quinoline)2]( C p=cyclopentadienyl).[6b]Attempts to isolate
the TiIIintermediates from our reactions by lowering the re-
action temperature or adding an additional ligand, such aspyridine, to the reaction system to stabilise the intermedi-
ates have been unsuccessful so far. Since the titanium(II) in-
termediates are coordinately unsaturated species with astrong tendency to lose two electrons, the two imine groupsin these Ti
IIintermediates would coordinate to the TiIIatom
and undergo oxidative coupling immediately to form thecomplexes 4as shown in Scheme 3. The Ti
II- and ZrII-medi-
ated C /C0C bond-forming reactions of alkenes, alkynes, car-
bonyls, and imines have been well documented.[17a,19]From
the proposed mechanism shown in Scheme 3, 9,10-dihydro-
phenanthrenediamide ligands with both cisandtrans config-
urations may be formed in the oxidative coupling C /C0C
bond-forming step. However, only the titanium complexeswith cis-9,10-dihydrophenanthrenediamide ligands have
been obtained so far. It is possible that only the intermedi-ate with the two imine bonds in a coplanar position canhave the two imine carbon atoms close to each other
[19]and
the oxidative coupling reaction can therefore take placeeasily to form the cis-diamide ligands. The cisselectivity of
this reaction system may also be related to the smaller
atomic radius of titanium, as trans -diamide ligands were ob-
tained in similar imine oxidative couplings mediated by sa-marium reagents.
[20]
Conclusions
In attempts to synthesise the titanium complexes [{ o-C6H4-
ACHTUNGTRENNUNG(CH=NR)}2TiCl2](2), chelating cis-9,10-dihydrophenanthre-
nediamide complexes of titanium ( 4and 5) have been ob-
tained by the reactions ofTiCl
4with two or three equiva-
lents of the corresponding o-
C6H4 ACHTUNGTRENNUNG(CH=NR)Li, followed by
sequential intramolecular C /C0C
bond-forming reductive elimi-
nation and oxidative coupling.Attempts to isolate the inter-mediates 2were unsuccessful.
No trans- 9,10-dihydrophenan-
threnediamide complex hasbeen obtained from these reac-tions. The synthetic yields of
complexes 4were found to change in the order 4a>4c>
4b.T h e cisconfigurations of complexes 4a–c,5aand 5c
were confirmed by X-ray crystallographic analysis.
1H and
13C NMR spectroscopic analysis revealed asymmetric struc-
tures for complexes 4cand5cin solution, probably because
the bulky tBu groups at the N atoms block the transforma-
tion between different conformations. A possible reaction
mechanism was proposed, based on the structures of com-
plexes 4and5.
Experimental Section
General : All manipulations of air- and water-sensitive compounds were
performed under an inert atmosphere of nitrogen by using standardSchlenk-line or glove-box techniques. Solvents were dried and purified
by known procedures and distilled under nitrogen before use. nBuLi and
TiCl
4were purchased from Aldrich and used as received without further
purification.1H and13C NMR spectra were measured on either a Varian
Mercury-300 or a Bruker Avance-500 NMR spectrometer. Elemental
analysis was performed on a Perkin-Elmer 2400 analyzer.
Synthesis of o-C6H4(CH=NC6H3iPr2-2,6)Br (1a) : A mixture of o-bromo-
benzaldehyde (8.71 g, 47.1 mmol), 2,6-diisopropylaniline (8.9 mL,47.1 mmol) and MgSO
4(1.0 g) in n-hexane (30 mL) was stirred for 2 h.
The mixture was filtered and the filtrate was evaporated to dryness in
vacuo to give the crude product as a yellow solid. Pure product (13.8 g,
40.1 mmol, 85%) was obtained as yellowish-green crystals by recrystalli-sation from ethanol at /C020
8C.1H NMR (300 MHz, CDCl3,2 58C, TMS):
d=1.20 (d,3J ACHTUNGTRENNUNG(H,H)=6.9 Hz, 12H; CH ACHTUNGTRENNUNG(CH3)2), 2.98 (sept,3J ACHTUNGTRENNUNG(H,H)=
6.9 Hz, 2H; C H ACHTUNGTRENNUNG(CH3)2), 7.16–7.21 (m, 3H; Ph /C0H), 7.39 (t, 1H; Ph /C0H),
7.45 (t, 1H; Ph /C0H), 7.65 (d, 1H; Ph /C0H), 8.29 (d, 1H; Ph /C0H), 8.59 ppm
(s, 1H; C H=NAr);13C NMR (300 MHz, CDCl3,2 58C, TMS): d=23.5-
ACHTUNGTRENNUNG(CH3),27.9 ( CH ACHTUNGTRENNUNG(CH3)2), 123.1,124.4,125.7, 127.7, 128.8, 132.3, 133.1,
Scheme 3. The proposed mechanism for the formation of 4.R E=reductive elimination, OC =oxidative cou-
pling.
Chem. Eur. J. 2010,16, 4394 – 4401 /C23 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org 4399FULL PAPERSynthesis of Titanium Complexes

134.6, 137.5, 148.9, 161.3 ppm ( CH=NAr); elemental analysis calcd (%)
for C19H22NBr: C 66.28, H 6.44, N 4.07; found: C 66.17, H 6.49, N 4.11.
Synthesis of o-C6H4(CH=NC6H3Me2-2,6)Br (1b) : Compound 1bwas pre-
pared in the same manner as 1awith 2,6-dimethylaniline (5.8 mL,
47.1 mmol) as starting material. Pure product (11.5 g, 39.9 mmol, 79%)was obtained as a yellowish oil by distillation under reduced pressure at82–83
8C/10 mmHg.1H NMR (300 MHz, CDCl3,2 58C, TMS): d=2.18 (s,
6H; C H3), 6.96–7.11 (m, 3H; Ph /C0H), 7.37(t, 1H; Ph /C0H), 7.45 (t, 1H;
Ph/C0H), 7.64 (d, 1H; Ph /C0H), 8.28 (d, 1H; Ph /C0H), 8.63 ppm (s, 1H; C H=
NAr);13C NMR (300 MHz, CDCl3,2 58C, TMS): d=18.5 ACHTUNGTRENNUNG(CH3) 124.2,
125.8, 127.0, 127.8, 128.3, 128.8, 132.4, 133.2, 134.8, 151.0, 162.0 ppm(CH=NAr); elemental analysis calcd (%) for C
15H14NBr: C 62.52, H
4.90, N 4.86; found: C 62.54, H 4.93, N 4.82.
Synthesis of o-C6H4 ACHTUNGTRENNUNG(CH=NtBu)Br (1c) : Compound 1cwas prepared in
the same manner as 1awith tert-butylaniline (5.9 mL, 56.5 mmol) as
starting material. Pure product (11.1 g, 46.2 mmol, 89%) was obtained as
a light yellow oil by distillation under reduced pressure at 54–55 8C/
10 mmHg.1H NMR (300 MHz, CDCl3,2 58C, TMS): d=1.31 (s, 9H; C-
ACHTUNGTRENNUNG(CH3)3), 7.20 (t, 1H; Ph /C0H), 7.30 (t, 1H; Ph /C0H), 7.52 (d, 1H; Ph /C0H),
7.99 (d, 1H; Ph /C0H), 8.60 ppm (s, 1H; C H=NAr);13C NMR (300 MHz,
CDCl3,2 58C, TMS): d=29.6 ( CH3), 57.9 ( C ACHTUNGTRENNUNG(CH3)3), 125.0, 127.4, 128.5,
131.2, 132.6, 135.3, 154.5 ppm ( CH=NAr); elemental analysis calcd (%)
for C11H14NBr: C 55.0, H 5.88, N 5.83; found: C 55.1, H 5.86, N 5.84.
Synthesis of [{ o-C6H4(CH=NC6H3iPr2-2,6)}TiCl3]( 3 a ) : A solution of
nBuLi (2.2 mmol) was added dropwise to a solution of 1a(760 mg,
2.2 mmol) in n-hexane (20 mL) at 0 8C. The reaction mixture was allowed
to warm to room temperature and stirred for 3 h. The lithium salt of 1a
formed was collected on a frit, washed with n-hexane (2/C1485 mL), and
dried under vacuum. The lithium salt (570 mg, 2.1 mmol) obtained wasdissolved in toluene (20 mL) and added to a solution of TiCl
4(398 mg,
2.1 mmol) in toluene (10 mL) at /C0788C. The reaction mixture was al-
lowed to warm to room temperature and stirred for 6 h. The precipitatewas filtered off, and the solvent was removed to leave a red solid. Re-crystallisation from CH
2Cl2/hexane gave the pure 3aas red crystals
(810 mg, 1.9 mmol, 87%), m.p. 109–110 8C;1H NMR (300 MHz, CDCl3,
258C, TMS): d=1.12 (d,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 6H; CH ACHTUNGTRENNUNG(CH3)2), 1.34 (d,
3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 6H; CH ACHTUNGTRENNUNG(CH3)2), 3.52 (sept,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 2H; C H-
ACHTUNGTRENNUNG(CH3)2), 7.24–7.56 (m, 6H; Ph /C0H), 8.15 (d, 1H; Ph /C0H), 8.28 ppm (s, 1H;
CH=NAr);13C NMR (300 MHz, CDCl3,2 58C, TMS): d=23.1 ( CH3),
26.2 ( CH3), 29.0 ( CH ACHTUNGTRENNUNG(CH3)2), 123.0, 124.1, 127.4, 128.5, 131.9, 135.9,
140.4, 141.5, 142.6, 146.3, 177.8 ppm ( CH=NAr); elemental analysis calcd
(%) for C19H22NCl3Ti: C 54.51, H 5.30, N 3.35; found: C 54.49, H 5.32, N
3.37.
Synthesis of [{ o-C6H4(CH=NC6H3Me2-2,6)}TiCl3]( 3 b ) : Complex 3bwas
synthesised in the same manner as 3awith 1b(630 mg, 2.2 mmol), nBuLi
(2.2 mmol), and TiCl4(398 mg, 2.1 mmol) as starting materials or re-
agents. Pure 3bwas obtained as a red crystalline solid (650 mg, 1.8 mmol,
82%), m.p. 95–96 8C;1H NMR (300 MHz, CDCl3,2 58C, TMS): d=2.58
(s, 6H; C H3), 7.15–7.65 (m, 6H; Ph /C0H), 8.24 (d, 1H; Ph /C0H), 8.40 ppm
(s, 1H; C H=NAr);13C NMR (300 MHz, CDCl3,2 58C, TMS): d=19.6
(CH3), 124.1, 125.3, 126.8, 127.6, 128.2, 129.0, 131.7, 132.9, 135.8, 142.4,
179.0 ppm ( CH=NAr); elemental analysis calcd (%) for C15H14NCl3Ti: C
49.70, H 3.89, N 3.86; found: C 49.08, H 3.82, N 3.78.
Synthesis of [{ o-C6H4 ACHTUNGTRENNUNG(CH=NtBu)}TiCl3]( 3 c ) : Complex 3cwas synthes-
ised in the same manner as 3awith 1c(530 mg, 2.2 mmol), nBuLi
(2.2 mmol) and TiCl4(398 mg, 2.1 mmol) as starting materials or re-
agents. Pure 3cwas obtained as a red crystalline solid (592 mg, 1.9 mmol,
85%), m.p. 89–91 8C;1H NMR (300 MHz, CDCl3,2 58C, TMS): d=1.67
(s, 9H; C H3), 7.26 (t, 1H; Ph /C0H), 7.68 (t, 1H; Ph /C0H), 7.80 (d, 1H; Ph /C0
H), 7.98 (d, 1H; Ph /C0H), 8.37 ppm (s, 1H; C H=NAr);13C NMR
(300 MHz, CDCl3,2 58C, TMS): d=31.8 ( CH3), 63.1 ( C ACHTUNGTRENNUNG(CH3)3), 124.2,
127.9, 128.8, 132.4, 133.7, 140.4, 169.5 ppm ( CH=NAr); elemental analysis
calcd (%) for C11H14NCl3Ti: C 42.01, H 4.49, N 4.45; found: C 42.11, H
4.39, N 4.37.
Synthesis of [{ cis-9,10-(NC6H3iPr2-2,6)2-9,10-dihydrophenanthrene}TiCl2]
(4a): Complex 4awas synthesised in the same manner as 3awith 1a
(760 mg, 2.2 mmol), nBuLi (2.2 mmol), and TiCl4(209 mg, 1.1 mmol) as
starting materials or reagents. Pure 4awas obtained as red crystals(521 mg, 0.79 mmol, 68%), m.p. 207–209 8C;1H NMR (300 MHz, CDCl3,
258C, TMS): d=1.11 (d,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 12H; C H3), 1.20 (d,3J ACHTUNGTRENNUNG(H,H)=
6.6 Hz, 12H; C H3), 3.29 (sept,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 4H; C H ACHTUNGTRENNUNG(CH3)2), 6.18 (s,
2H; C HN), 6.88 (d, 2H; Ph /C0H), 7.00–7.40 (m, 10H; Ph /C0H), 7.85 ppm (d,
2H; Ph /C0H);13C NMR (300 MHz, CDCl3,2 58C, TMS): d=25.0 ( CH3),
27.0 ( CH3), 29.4 ( CH ACHTUNGTRENNUNG(CH3)2), 72.6 ( CHN), 123.8, 124.9, 125.1, 127.3,
128.5, 129.3, 129.4, 132.3, 134.7, 140.4 ppm; elemental analysis calcd (%)
for C38H44N2Cl2Ti: C 70.48, H 6.85, N 4.33; found: C 70.45, H 6.83, N
4.31.
Synthesis of [{ cis-9,10-(NC6H3Me2-2,6)2-9,10-dihydrophenanthrene}TiCl2]
(4b): Complex 4bwas synthesised in the same manner as 3awith 1b
(630 mg, 2.2 mmol), nBuLi (2.2 mmol) and TiCl4(209 mg, 1.0 mmol) as
starting materials or reagents. Pure 4bwas obtained as red crystals
(273 mg, 0.54 mmol, 54%), m.p. 190–191 8C;1H NMR (300 MHz, CDCl3,
258C, TMS): d=2.42 (s, 12H; C H3), 6.39 (s, 2H; C HN), 6.84 (d, 2H; Ph /C0
H), 7.00–7.40 (m, 10H; Ph /C0H), 7.85 ppm (d, 2H; Ph /C0H);13C NMR
(300 MHz, CDCl3,2 58C, TMS): d=19.9 ( CH3), 71.5 ( CHN), 123.3, 127.7,
128.3, 128.9, 129.2, 129.3, 129.5, 131.0, 132.3, 134.7 ppm; elemental analy-
sis calcd (%) for C30H28N2Cl2Ti : C 67.31, H 5.27, N 5.23; found: C 67.30,
H 5.26, N 5.21.
Synthesis of [{ cis-9,10-(N tBu)2-9,10-dihydrophenanthrene}TiCl2] (4c).
Complex 4cwas synthesised in the same manner as 3awith 1c(530 g,
2.2 mmol), nBuLi (2.2 mmol), and TiCl4(209 mg, 1.1 mmol) as starting
materials or reagents. Pure 4cwas obtained as red crystals (334 mg,
0.81 mmol, 65%), m.p. 185–186 8C;1H NMR (300 MHz, CDCl3,2 58C,
TMS): d=1.09 (s, 9H; C H3), 1.61 (s, 9H; C H3), 4.95 (d,3J ACHTUNGTRENNUNG(H,H)=3.9 Hz,
1H; C HN), 6.05 (d,3J ACHTUNGTRENNUNG(H,H)=3.9 Hz, 1H; C HN), 7.20–7.80 ppm (m, 8H;
Ph/C0H);13C NMR (300 MHz, CDCl3,2 58C, TMS): d=28.0 ( CH3), 29.4
(CH3), 63.1 ( C ACHTUNGTRENNUNG(CH3)3), 63.7 ( C ACHTUNGTRENNUNG(CH3)3), 66.1 ( CHN), 68.9 ( CHN), 123.7,
124.6, 127.5 128.3, 130.3, 130.9, 131.3, 132.5, 135.4, 136.4, 137.6,
139.1 ppm; elemental analysis calcd (%) for C22H28N2Cl2Ti: C 60.16; H
6.43; N 6.38; found: C 60.15; H 6.42; N 6.39.
Synthesis of [{ cis-9,10-(NC6H3iPr2-2,6)2-9,10-dihydrophenanthrene} ACHTUNGTRENNUNG{o-
C6H4(CH=NC6H3iPr2-2,6)}TiCl] (5a) : Complex 5awas synthesised in the
same manner as 3awith 1a(760 mg, 2.2 mmol), nBuLi (2.2 mmol), and
TiCl4(133 mg, 0.7 mmol) as starting materials or reagents. Pure 5awas
obtained as red crystals (561 mg, 0.62 mmol, 89%), m.p. 135–136 8C;
1H NMR (300 MHz, CDCl3,2 58C, TMS): d=0.44 (d,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz,
6H; CH ACHTUNGTRENNUNG(CH3)2), 0.52 (d,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 6H; CH ACHTUNGTRENNUNG(CH3)2), 0.70 (d,
3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 6H; CH ACHTUNGTRENNUNG(CH3)2), 0.90 (d,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 6H; CH-
ACHTUNGTRENNUNG(CH3)2), 1.28 (d,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 6H; CH ACHTUNGTRENNUNG(CH3)2), 1.50 (d,3J ACHTUNGTRENNUNG(H,H)=
6.6 Hz, 6H; CH ACHTUNGTRENNUNG(CH3)2), 2.27 (sept,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 2H; C H ACHTUNGTRENNUNG(CH3)2),
3.37 (sept,3J ACHTUNGTRENNUNG(H,H)=6.6 Hz, 2H; C H ACHTUNGTRENNUNG(CH3)2), 3.65 (sept,3J ACHTUNGTRENNUNG(H,H)=
6.6 Hz, 2H; C H ACHTUNGTRENNUNG(CH3)2), 6.06 (s, 2H; C HN), 6.30 (d, 2H; Ph /C0H), 6.72–
7.39 (m, 18H; Ph /C0H), 7.88 (d, 1H; Ph /C0H), 7.92 ppm (s, 1H; C H=NAr);
13C NMR (300 MHz, CDCl3,2 58C, TMS): d=22.3 ( CH3), 23.0 ( CH3),
25.4 ( CH3), 25.9 ( CH3), 26.2 ( CH3), 26.4 ( CH3), 28.1 ( CH ACHTUNGTRENNUNG(CH3)2), 28.2
(CH ACHTUNGTRENNUNG(CH3)2), 28.9 ( CH ACHTUNGTRENNUNG(CH3)2), 72.2 ( CHN), 122.8, 123.6, 123.7, 125.7,
126.1, 126.5, 126.9, 127.3, 128.4, 128.7, 130.1, 130.9, 132.8, 137.0, 137.9,140.9, 141.1, 145.5, 148.9, 178.1, 191.3 ppm ( CH=NAr); elemental analysis
calcd (%) for C
57H66N3ClTi : C78.11, H7.59, N4.79; found: C78.13,
H7.57, N4.81.
Synthesis of [{ cis-9,10-(NC6H3Me2-2,6)2-9,10-dihydrophenanthrene} ACHTUNGTRENNUNG{o-
C6H4(CH=NC6H3Me2-2,6)}TiCl] (5b) : Complex 5bwas synthesised in the
same manner as 3awith 1b(630 mg, 2.2 mmol), nBuLi (2.2 mmol), and
TiCl4(133 mg, 0.7 mmol) as starting materials or reagents. Complex 5b
was obtained as an oily crude product. Pure product has not been ob-
tained yet.1H NMR (300 MHz, CDCl3,2 58C, TMS): d=2.19 (s, 12H;
CH3), 2.60 (s, 6H; C H3), 6.17 (s, 2H; C HN), 6.90–7.60 (m, 20H; Ph /C0H),
8.00 (d, 1H; Ph /C0H), 8.43 ppm (s, 1H; C H=NAr).
Synthesis of [{ cis-9,10-(N tBu)2-9,10-dihydrophenanthrene} ACHTUNGTRENNUNG{o-C6H4 ACHTUNGTRENNUNG(CH=
NtBu)}TiCl] (5c) : Complex 5cwas synthesised in the same manner as 3a
with 1c(530 mg, 2.2 mmol), nBuLi (2.2 mmol), and TiCl4(133 mg,
0.7 mmol) as starting materials or reagents. Pure 5cwas obtained as red
crystals (362 mg, 0.61 mmol, 87%), m.p. 127–128 8C;1H NMR (300 MHz,
CDCl3,2 58C, TMS): d=1.17 (s, 9H; C ACHTUNGTRENNUNG(CH3)3), 1.43 (s, 9H; C ACHTUNGTRENNUNG(CH3)3),
1.75 (s, 9H; C ACHTUNGTRENNUNG(CH3)3), 4.68 (d,3J ACHTUNGTRENNUNG(H,H)=4.2 Hz, 1H; C HN), 6.53 (d,
3J ACHTUNGTRENNUNG(H,H)=4.2 Hz, 1H; C HN), 7.20–7.65 (m, 8H; Ph /C0H), 7.76 (t, 2H; Ph /C0
www.chemeurj.org /C23 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 2010,16, 4394 – 4401 4400
Y. Mu et al.

H), 7.86 (t, 2H; Ph /C0H), 8.49 ppm (s, 1H; C H=NAr);13C NMR
(300 MHz, CDCl3,2 58C, TMS): d=28.0 ( CH3), 29.2 ( CH3), 31.6 ( CH3),
59.9 ( C ACHTUNGTRENNUNG(CH3)3), 60.3 ( C ACHTUNGTRENNUNG(CH3)3), 62.0 ( C ACHTUNGTRENNUNG(CH3)3), 64.9 ( CHN), 75.1 ( CHN),
122.4, 124.6, 125.9, 125.7, 127.5, 127.7, 127.9, 128.1, 128.5, 129.5, 129.8,129.9, 130.7, 131.2, 137.3, 137.8, 141.7, 142.2, 171.1, 190.2 ppm (CH =
NAr); elemental analysis calcd (%) for C
33H42N3ClTi : C 70.27, H 7.51, N
7.45; found: C 70.28, H 7.52, N 7.44.
X-ray structure determinations of 3a, 4a–c, 5a and 5c : Single crystals of
3a,4a–c, 5a and5csuitable for X-ray structural analysis were obtained
from the CH2Cl2/hexane mixture. The data were collected at 293 K on a
Bruker SMART CCD diffractometer using graphite-monochromated
MoKaradiation ( l=0.71073 /C138) for 3a,4c,and5c, and on a Rigaku R-
AXIS RAPID IP diffractometer equipped with graphite-monochromatedMo
Karadiation ( l=0.71073 /C138) for 4a,4band 5a. The structures were
solved by direct methods[21]and refined by full-matrix least-squares on
F2. All non-hydrogen atoms were refined anisotropically, and the hydro-
gen atoms were included in idealised positions. All calculations were per-formed using the SHELXTL
[22]crystallographic software packages. De-
tails of the crystal data, data collections, and structure refinements are
summarised in Table 2. CCDC-739019 ( 3a), 739020 ( 4a), 739021 ( 4b),
739022 ( 4c), 739023 ( 5a), and 739024 ( 5c) contain the supplementary
crystallographic data for this paper. These data can be obtained free ofcharge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgements
This work was supported by the National Natural Science Foundation of
China (Nos. 20674024 and 20772044).
[1] Selected reviews: a) V. Ritleng, C. Sirlin, M. Pfeffer, Chem. Rev.
2002,102, 1731–1769; b) L. Resconi, L. Cavallo, A. Fait, F. Piemon-
tesi, Chem. Rev. 2000,100, 1253–1345; c) T.-Y. Luh, M. K. Leung,
K. T. Wong, Chem. Rev. 2000,100, 3187–3204; d) G. J. P . Britovsek,
V. C. Gibson, D. F. Wass, Angew. Chem. 1999,111, 448–468; Angew.
Chem. Int. Ed. 1999,38, 428–447; e) I. Ojima, M. Tzamarioudaki,
Z. Li, R. J. Donovan, Chem. Rev. 1996,96, 635–662.
[2] a) A. Motta, I. L. Fragala, T. J. Marks, J. Am. Chem. Soc. 2007,129,
7327–7338; b) J. D. Scollard, D. H. McConville, N. C. Payne, J. J.
Vittal, Macromolecules 1996,29, 5241–5243; c) J. C. Sierra, D. H/C252er-
l/C228nder, M. Hill, G. Kehr, G. Erker, R. Frçhlich, Chem. Eur. J. 2003,
9, 3618–3622; d) M. B. Bertrand, J. D. Neukom, J. P . Wolfe J. Org.
Chem. 2008,73, 8851–8860; e) H. R. Bigmore, S. R. Dubberley, M.
Kranenburg, S. C. Lawrence, A. J. Sealey, J. D. Selby, M. A. Zuide-veld, A. R. Cowley, P . Mountford, Chem. Commun. 2006,118, 436–
438.
[3] a) S. B. Jhaveri, K. R. Carter, Chem. Eur. J. 2008,14, 6845–6848;
b) T. Nagano, T. Hayashi, Org. Lett. 2005,7, 491–493; c) J. D. Scol-
lard, D. H. McConville, J. Am. Chem. Soc. 1996,118, 10008–10009;
d) N. Borduas, D. A. Powell, J. Org. Chem. 2008,73, 7822–7825;
e) F. Rosenfeldt, G. Erker, Tetrahedron Lett. 1980,21, 1637–1640;
f) S. A. Cummings, R. Radford, G. Erker, G. Kehr, R. Frçhlich,
Or-
ganometallics 2006,25, 839–842.
[4] a) J. W. Strauch, G. Erker, G. Kehr, R. Frçhlich, Angew. Chem.
2002,114, 2662–2664; Angew. Chem. Int. Ed. 2002,41, 2543–2546;
b) R. J. Long, V. C. Gibson, A. J. P . White, Organometallics 2008,27,
235–245; c) L. Rocchigiani, C. Zuccaccia, D. Zuccaccia, A. Mac-chioni, Chem. Eur. J. 2008,14, 6589–6592; d) A. Motta, I. L. Fraga-
la, T. J. Marks, J. Am. Chem. Soc. 2007,129, 7327–7338; e) X. H.
Yang, X. L. Sun, F. B. Han, B. Liu, Y. Tang, Z. Wang, M. L. Gao,Z. W. Xie, S. Z. Bu, Organometallics 2008,27, 4618–4624.[5] a) R. Beckhaus, J. Oster, I. Strauss, M. Wagner, Synlett 1997, 241–
249; b) P . Stepnicka, R. Gyenpes, I. Cisarova, M. Horacek, J. Kubis-
ta, K. Mach, Organometallics 1999,18, 4869–4880; c) U. Rosenthal,
Angew. Chem. 2004,116, 3972–3977; Angew. Chem. Int. Ed. 2004,
43, 3882–3887; d) G. Erker, Acc. Chem. Res. 1984,17, 103–109;
e) R. Beckhaus, K. H. Thiele, J. Organomet. Chem. 1986,317,2 3 –
31; f) J. Campora, S. L. Buchwald, E. Gutierrez-Puebla, A. Monge,Organometallics 1995,14, 2039–2046.
[6] a) S. Kraft, R. Beckhaus, D. Haase, W. Saak, Angew. Chem. 2004,
116, 1609–1614; Angew. Chem. Int. Ed. 2004,43, 1583–1587;
b) I. M. Piglosiewicz, R. Beckhaus, W. Saak, D. Haase, J. Am. Chem.
Soc. 2005,127, 14190–14191; c) M. R. Haneline, A. F. Heyduk, J.
Am. Chem. Soc. 2006,128
, 8410–8411.
[7] a) R. K. Merwin, R. C. Schnabel, J. D. Koola, D. M. Roddick, Org-
nometallics 1992,11, 2972–2978; b) Z. Z. Qiu, Z. W. Xie, Angew.
Chem. 2008,120, 6674–6677; Angew. Chem. Int. Ed. 2008,47, 6572–
6575.
[8] a) A. Kasatkin, T. Nakagawa, S. Okamoto, F. Sato, J. Am. Chem.
Soc. 1995,117, 3881–3882; b) S. L. Buchwald, B. T. Watson, M. W.
Wannamaker, J. C. Dewan, J. Am. Chem. Soc. 1989,111, 4486–
4494; c) S. O. Agustsson, C. H. Hu, U. Englert, T. Marx, L. Wese-
mann, C. Ganter, Organometallics 2002,21, 2993–3000.
[9] R. B. Grossman, S. L. Buchwald, J. Org. Chem. 1992,57, 5803–5805.
[10] P . G. Hayes, G. C. Welch, D. J. H. Emslie, C. L. Noack, W. E. Piers,
M. Parvez, Organometallics 2003,22, 1577.
[11] V. Snieckus, Chem. Rev. 1990,90, 879–933.
[12] T. I. Baiz, J. A. R. Schmidt, Organometallics 2007,26, 4094–4097.
[13] a) M. Mitani, R. Furuyama, J. I. Mohri, J. Saito, S. Ishii, H. Terao, T.
Nakano, H. Tanaka, T. Fujita, J. Am. Chem. Soc. 2003,125, 4293–
4305; b) Y. T. Zhang, J. H. Wang, Y. Mu, Z. Shi, C. S. L/C252, Y. R.Zhang, L. J. Qiao, S. H. Feng, Organometallics 2003,22, 3877–3883.
[14] a) G. D. Smith, P . E. Fanwick, I. P . Rothwell, Inorg. Chem. 1990,29,
3221–3226; b) J. Zhang, Y. J. Lin, G. X. Jin, Organometallics 2007,
26, 4042–4047.
[15] a) N. A. Ketterer, J. W. Ziller, A. L. Rheingold, A. F. Heyduk, Orga-
nometallics 2007,26, 5330–5338; b) M. E. G. Skinner, T. Toupance,
D. A. Cowhig, B. R. Tyrrell, P . Mountford, Organometallics 2005,
24,
5586–5603.
[16] a) K. P . Bryliakov, E. A. Kravtsov, D. A. Pennington, S. J. Lancaster,
M. Bochmann, H. H. Brintzinger, E. P . Talsi, Organometallics 2005,
24, 5660–5664; b) A. F. Mason, G. W. Coates, J. Am. Chem. Soc.
2004,126, 16326–16327.
[17] a) M. G. Thorn, J. E. Hill, S. A. Waratuke, E. S. Johnson, P . E. Fan-
wick, I. P . Rothwell, J. Am. Chem. Soc. 1997,119, 8630–8641; b) C.
Lefeber, P . Arndt, A. Tillack, W. Baumann, R. Kempe, V. V. Burla-kov, U. Rosenthal, Organometallics 1995,14, 3090–3093.
[18] a) D. F. Herman, W. R. Nelson, J. Am. Chem. Soc. 1953,75, 3877–
3882; b) D. F. Herman, W. R. Nelson, J. Am. Chem. Soc. 1953,75,
3882–3887.
[19] L. D. Durfee, A. K. McMullen, I. P . Rothwell, J. Am. Chem. Soc.
1988,110, 1463–1467.
[20] a) N. Taniguchi, T. Hata, M. Uemura Angew. Chem. 1999,111,
1311–1314; Angew. Chem. Int. Ed. 1999, 38, 1232–1235; Angew.
Chem. Int. Ed. 1999,38, 1232–1235; b) A. O. Larsen, R. A. Talor,
P . S. White, M. R. Gagn, Organometallics 1999,18, 5157–5162; c) R.
Yanada, N. Negoro, M. Okaniwa, Y. Miwa, T. Taga, K. Yanada, T.
Fujita, Synlett 1999, 537–540.
[21] SHELXTL; PC Siemens Analytical X-ray Instruments: Madison
WI,1993.
[22] G. M. Sheldrick, SHELXTL Structure Determination Programs,
Version 5.0; PC Siemens Analytical Systems: Madison, WI, 1994.
Received: November 2, 2009
Published online: March 5, 2010
Chem. Eur. J. 2010,16, 4394 – 4401 /C23 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org 4401FULL PAPERSynthesis of Titanium Complexes