Synthesis and investigation of the stability of Ti(III) β-diketiminato complexes. Structure of the tetrameric non-metallocene titanium fluoride complex (L2)4Ti4F6O2·2toluene supported by the β-diketiminato ligan

Article abstract of DOI:10.1016/S0277-5387(03)00345-0

The titanium β-diketiminato complexes (L1)TiCl₂ (1), (L1)TiCl(N2,6-ⁱPr₂C₆H₃) (2), and (L2)₂TiCl (3) [L1 = (2,6-ⁱPr₂C₆H₃)NC(Me)CHC(Me)N (2,6-

Full text of DOI:10.1016/S0277-5387(03)00345-0

Polyhedron 22 (2003) 2669ꢁ2681
/
www.elsevier.com/locate/poly
Synthesis and investigation of the stability of Ti(III) b-diketiminato
complexes. Structure of the tetrameric non-metallocene titanium
fluoride complex (L2)4Ti4F6O2×
/
2toluene supported by the
b-diketiminato ligand
Grigori B. Nikiforov, Herbert W. Roesky *, Jorg Magull, Thomas Labahn,
¨
Denis Vidovic, Mathias Noltemeyer, Hans-Georg Schmidt, Narayan S. Hosmane
Institut fur Anorganische Chemie, Universitat Gottingen, Tammannstrasse 4, D-37077 Gottingen, Germany
¨ ¨ ¨ ¨
Received 13 March 2003; accepted 14 May 2003
Dedicated to Professor Hans Bock on the occasion of his 75th birthday
Abstract
The titanium b-diketiminato complexes (L1)TiCl2 (1), (L1)TiCl(N2,6-i Pr2C6H3) (2), and (L2)2TiCl (3) [L1ꢀ
(2,6-i Pr2C6H3)NC(Me)CHC(Me)N(2,6-i Pr2C6H3), L2ꢀiPrNC(Me)CHC(Me)Ni Pr] have been prepared by the reaction of the
/
/
lithium salt of the ligand, L, with titanium trichloride. Complex 2 was isolated from supernatant solutions of 1 containing excess of
the (L1)Li salt. The monochloride complex [(L2)TiCl(NiPr)]2 (4) was prepared by reduction of (L2)2TiCl2 with the excess of Na/K
alloy. Fluorination of the monochloride complex 3 with Me3SnF affords polymeric [(L2)TiF2]n (5). Oxidation of 5 gives the
tetrameric complex, (L2)4Ti4F6O2×
/
2toluene (6). Compounds 1ꢁ6 were characterized by single crystal X-ray structural analyses,
/
elemental analyses, NMR and mass spectra. The bulky ligand (L1) stabilizes the Ti(III) complex 1 with an unusual distorted square-
planar pyramidal geometry around the titanium atom, by sigma bonding to the metal. The less bulky ligand (L2) in complexes 3, 4
and 6 has mixed s and p coordination to the titanium center. Investigation of the Cꢀ
/
C, Nꢀ
/
C distances in the NCCCN unit of the
coordinated b-diketiminato ligands (L1) and (L2) demonstrated the localization of the double bonds in the ligand in complexes 1ꢁ
/3
and 6. The stability of the complexes in solution was studied by means of NMR spectroscopy. Complexes 2 and 4 are stable in
solution, the polymeric and the tetrameric nature of complexes 5 and 6 is not evident in C6D6 solution. The (L2)2TiCl stoichiometry
of the complex is unstable.
# 2003 Elsevier Science Ltd. All rights reserved.
Keywords: Coordination chemistry; b-Diketiminato ligand; Titanium(III); Chloride; Fluoride
1. Introduction
The b-diketiminates usually give stable complexes with
the metal cations in an oxidation state of ꢂ3 [5]. During
/
The area of metal b-diketiminato complexes was
intensively developed in recent years. The b-diketimi-
nates play a useful role as monoanionic spectator
ligands by virtue of their tuneable and extensive steric
demands and their diversity of bonding modes [1]. They
can stabilize low metal oxidation states [2] and form
complexes with unusual coordination numbers [3,4].
the last decade, a considerable attention was focused on
titanium complexes [5f,6]. It was found that the b-
diketiminato complexes of Ti(III) with the general
formula LTiCl2 in the presence of excess methylalumi-
noxane [5f] or B(C6F5)3 [6] catalyze the homopolymer-
ization of ethylene and the copolymerization of ethylene
with a-olefins. Several compounds of general formula
LTiX2 (Xꢀ
prepared and complexes LTiCl2×
(Me))2CH) [5f], LTiCl2 (Lꢀ((2,4,6-Me3C6H2)NC-
(Me))2CH, and
((2,4,6-Me3C6H2)NC(tBu))2CH)
/
Cl, Me, Lꢀ
/
b-diketiminato ligands) were
/
2THF (Lꢀ(PhNC-
/
* Corresponding author. Tel.: ꢂ
3373.
E-mail address: hroesky@gwdg.de (H.W. Roesky).
/
49-551-39-3001; fax: ꢂ49-551-39-
/
/
0277-5387/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0277-5387(03)00345-0

2670
G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ2681
/
LTiMe2 (Lꢀ
structurally characterized.
/
((2,4,6-Me3C6H2)NC(Me))2CH) [6] were
to note that TiCl3 does not dissolve completely in THF
during the reaction. Even after 10 days of the reaction
some amount of TiCl3 suspension was found in the
supernatant liquid. The interaction of TiCl3 with less
bulky ligands, (PhNC(Me))2CH [5f], or ((2,4,6-
Me3C6H2)NC(Me))2CH [6], proceeds quickly and gives
high yields of products. Complex LTiCl2 (deep red/
brown crystals) with the same ligand (L1) was prepared
by Budzelaar et al. [6] and characterized by elemental
analysis. Green colored single crystals of (L1)TiCl2 (1),
suitable for X-ray diffraction analysis, were obtained by
crystallization from its toluene solution.
There is a general interest in the chemistry of the
titanium b-diketiminato complexes from several per-
spectives including practical, synthetic and theoretical
implications. Our interest in the chemistry of titanium b-
diketiminato complexes stems from their potential use
as novel olefin polymerization catalysts. Also, the b-
diketiminato complexes of Ti(III) with bulky ligands can
be considered as versatile starting materials for prepar-
ing low valent titanium species and for stabilization of
titanium fluoride complexes. Herein we report the
synthesis and characterization, including the stability,
of the Ti(III) b-diketiminato complexes (L1)TiCl2 (1),
A brown solution was obtained after washing of the
reaction product of (L1)Li and TiCl3 with pentane.
From this solution the red crystalline substance was
(L2)2TiCl
(2),
(L1ꢀ
/
(2,6-iPr2C6H3)NC(Me)CHC-
PrNC(Me)CHC(Me)NiPr,
(Me)N(2,6-iPr2C6H3); L2ꢀi
/
obtained
that
appeared
to
be
complex
(L1)TiCl(N2,6-iPr2C6H3) (2). The monochloride com-
plex (L1)2TiCl was not isolated even with excess of
(L1)Li salt and after evaporation of pentane; instead, a
dark-brown viscous oil was collected. The EI MS
spectrum of a small red crystal covered with this oil
exhibited the heaviest fragment that can be assigned to
along with the first Ti(IV) complexes with the b-
diketiminato ligand (L1)TiCl(N2,6-iPr2C6H3) (3),
[(L2)TiCl(iPrN)]2 (4) and the titanium fluoride com-
plexes [(L2)TiF2]n (5) and (L2)4Ti4F6O2×/2toluene (6).
the [(L1)2TiClꢂ ꢁ
C12H17] cation.
/
2. Results and discussion
Complexes (L1)TiCl2 1 and (L1)TiCl(N2,6-iPr2C6H3)
(2) crystallize in the monoclinic space group P21/n.
Selected bond lengths and angles of 1 and 2 are listed in
Table 1; a summary of the crystallographic data and
refinement parameters for the structures of 1 and 2 are
given in Table 3.
The Ti(III) dichloride complex, (L1)TiCl2, was pre-
pared by the reaction of LLi and TiCl3 in THF, followed
by washing with pentane and recrystallization from
toluene (Scheme 1). There were no observable reactions
in solutions of Et2O, toluene and hexane. It is important
Scheme 1. Synthesis of the complexes 1 and 2.

G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ
/2681
2671
Table 1
Selected bond lengths (A) and angles (8) for 1 and 2
distances are similar to those found for Ti(III) com-
plexes with two bridging chlorine atoms [Ti(m-
˚
˚
Cl)Cl2(Me2P(CH2)2PMe2)]2 [8] (Tiꢀ
/
Cl 2.437(2) A) and
Bond lengths
Bond angles
slightly shorter than those for {[h8-1,4-(Si-
Me3)2C8H6]Ti(m-Cl)}2(THF) [9], [Cp2Ti(m-Cl)]2,
[(C5H4Me)Ti(m-Cl)]2 [10] (TiꢀCl 2.480(2); 2.536(2);
Complex 1
Tiꢀ
Tiꢀ
Tiꢀ
Tiꢀ
N(1)ꢀ
N(2)ꢀ
C(2)ꢀ
C(3)ꢀ
/
N(1)
N(2)
Cl(2)
Cl(3)
2.068(2)
2.093(2)
2.439(1)
2.254(1)
1.338(4)
1.331(4)
1.396(4)
1.407(4)
N(1)ꢀ
N(1)ꢀ
N(1)ꢀ
Cl(2)ꢀ
Cl(2)ꢀ
Cl(3)ꢀ
/
Tiꢀ
Tiꢀ
Tiꢀ
Tiꢀ
Tiꢀ
Tiꢀ
/
N(2)
Cl(2)
Cl(3)
87.14(10)
144.08(7)
104.38(7)
111.19(4)
89.83(7)
/
/
/
/
˚
2.566(2) A, respectively). The terminal Cl(3) in 1 is
almost perpendicular to the equatorial plane, as evi-
/
/
/
/
/
/
Cl(1)
N(2)
N(2)
/
C(2)
C(4)
/
/
denced from the angle [N(2)ꢀ
/
Tiꢀ
/
Cl(3)ꢀ102.67(7)8]
/
/
/
/
102.67(7)
(Table 1). The titanium atom is penta-coordinated.
The two nitrogen atoms and the chlorine atoms on
titanium are involved in a distorted square-planar
pyramidal geometry around the metal center.
/C(3)
/C(4)
Complex 2
Tiꢀ
Tiꢀ
Tiꢀ
Tiꢀ
N(1)ꢀ
N(2)ꢀ
/
N(1)
N(2)
N(3)
Cl(1)
2.020(7)
2.026(7)
1.710(8)
2.315(2)
1.367(14)
1.316(12)
1.424(10)
1.390(12)
N(1)ꢀ
N(1)ꢀ
N(1)ꢀ
N(3)ꢀ
N(2)ꢀ
N(3)ꢀ
/
Tiꢀ
Tiꢀ
Tiꢀ
Tiꢀ
Tiꢀ
Tiꢀ
/
N(2)
N(3)
Cl(1)
Cl(1)
Cl(1)
N(2)
95.1(3)
113.3(3)
114.9(2)
116.0(2)
108.03(17)
106.8(3)
The bond lengths between titanium and nitrogen
atoms of diimine in complex 2 are nearly the same,
but shorter than those in Ti(IV) a-iminato complex
/
/
/
/
/
/
/
/
/
/
C(13)
C(15)
/
/
LTiCl2(N2,6-iPr2C6H3)×
/
Py (Tiꢀ
PhNC(Me)C(Me)NPh) [11]. However, they are
similar to those in several titanium complexes with Tiꢀ
N single bonds (TiꢀN 2.025(2) [15], 2.195(3) [13],
/
N 2.200(5) and 2.317(4)
/
/
/
˚
A, Lꢀ
/
C(13)ꢀ
C(14)ꢀ
/C(14)
/
/C(15)
/
˚
2.006(2) [12] A).
The TiꢀN(3) distance is considerably shorter than
the other two TiꢀN(1) and TiꢀN(2) in the complex
X-ray structural analysis proved that compound 1 is
dimeric in the solid state (Fig. 1), while other known
Ti(III) b-diketiminato complexes with less bulky ligands
/
/
/
and is comparable with titanium nitrogen double bond
length in Ti(IV) complexes [Ti(NSiMe3)(L1)Cl],
Lꢀ(PhNC(Me))2CH, ((2,4,6-Me3C6H2)NC(Me))2CH,
/
((2,4,6-Me3C6H2)NC(tBu))2CH are monomeric [5f,6].
Compound 2 is solvent-free and monomeric (Fig. 2).
In both complexes 1 and 2 the b-diketiminato ligand
coordinates to the metal center through the two nitrogen
atoms. The NCCCN unsaturated back bone of the
[Ti(NtBu)(L2)Cl]Cl (L1, L2ꢀ
[13],
C5H4N)C(Me)(CH2NSiMe3)2}Ti(NtBu)×
/
triazacyclononane ligands)
[TiCl2(NC6H4Me-2)(Py)2]2
[14],
{k3N-(2-
/
Py [15] Ti(N-
N 1.718(2);
2,6-iPr2C6H3)({(tBuN)CH2}3)Cl2 [16] (Tiꢀ
/
˚
1.699(2); 1.711(2); 1.701(2); 1.713(3) A, respectively).
The Ti bound to three nitrogen atoms and a chlorine
atom are involved in a distorted tetrahedral geometry
around the metal center indicating its coordination
number as four.
˚
ligand is almost planar, with 0.031 (3) A deviation from
˚
planarity in 1, 0.037 (15) A in 2. The titanium atom is
out of plane of the diimine ligand framework by 0.79 (3)
˚
˚
A in 1 and 1.030 (5) A in 2. The geometries of each
(L1)TiCl2 unit of the complex 1 and (L1)Ti fragment in
2 are similar to that of the titanium(III) complex, LTiX2
Elemental analysis confirms the anticipated formula
as (L1)TiCl2 and shows that compound 1 is solvent-free
and contains no lithium chloride impurity. The compo-
sition of the unanticipated formula (L1)TiCl(N-
2,6-iPr2C6H3), that resulted from the X-ray structural
analysis, is also consistent with the elemental analysis of
the red crystals of 2.
Complexes 1 and 2 were studied by means of mass
spectrometry. In the EI MS of 1 is detected the
molecular ion [Mꢂ] and several fragments. Complex 2
exhibits the molecular ion [Mꢂ] as well as an intensive
peak of the [Mꢂ-NC12H17] cation in the EI MS
spectrum. Proton NMR spectra of 1 contain a set of
broad resonances (Dn1/2 ranging from 50 to 1000 Hz)
and a number of sharp resonances that are assigned to
the coordinated ligand. Nonetheless, the fine structures
of the resonances due to the paramagnetic nature of
Ti(III) complex could not be observed even at low
temperatures. The proton NMR spectra of 2 in C6D6
showed only a set of resonances. The two Me groups of
the backbone of the ligand are magnetically non-
(Xꢀ
(Lꢀ((2,4,6-Me3C6H2)NC(Me))2CH, ((2,4,6-Me3C6H2)-
NC(tBu))2CH). Comparison of the Cꢀ
C, CꢀN dis-
/
Cl, Me) [6], containing the b-diketiminato ligands
/
/
/
tances in the NCCCN unit of 1 and 2 (Table 1)
demonstrates the localization of double bonds, like in
compound (L1)H [7] (Scheme 2).
The titaniumꢁ
with those in complex LTiCl2 (2.087
(PhNC(Me))2CH) [5f]), where the titanium center has
/
nitrogen distances in 1 are comparable
˚
A
(Lꢀ
/
a coordination number 6 and longer than those in
˚
LTiCl2 (1.983(3), 1.964(3) A, Lꢀ
/
((2,4,6-Me3C6H2)NC-
˚
(Me))2CH; 1.986(1) A, Lꢀ
/
((2,4,6-Me3C6H2)NC(tBu))2-
CH [6]), where the Ti atom is four coordinated.
While the titaniumꢁterminal chlorine bond length in
1 is short, the titaniumꢁbridging chlorine distance is
longer (Table 1) than those in known b-diketiminato
/
/
˚
complexes of Ti(III), LTiCl2 (Tiꢀ
/
Cl 2.395 A [5f],
2.295(1), 2.297 (6) A [6]), in which two terminal chlorine
atoms are bonded to Ti. The titaniumꢁbridging chlorine
˚
/

2672
G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ2681
/
The isolation of complex 2 confirms the cleavage of
the CꢁN double bond in the b-diketiminato unit. This
/
phenomenon can be explained based on the following
facts. The monochloride complex, {(L1)2TiCl}, cannot
be recovered from the solution containing
TiCl3(THF)X ꢁ
/
(L1)Li(THF)X with the excess (L1)Li
C12H17] was found in
salt, but the cation [(L1)2TiClꢂ ꢁ
/
the EI MS. It is therefore possible that the {(L1)2TiCl}
moiety could exist in solution but this unit is unstable
due to the presence of two bulky b-diketiminato ligands
in the internal sphere and slowly decomposed to give 2
as a final product. Thus, coordination of the b-
diketiminato molecule to the titanium center plays an
important role in the cleavage of Cꢁ
/N double bond in
the molecule.
To investigate the stability of the titanium(III) b-
diketiminato complex L2TiCl, the reaction between the
(L2)Li salt (L2 is less bulky ligand (iPrNC(Me))2CH)
and TiCl3 in 2:1 molar ratio was studied. The reaction
product, (L2)2TiCl (3), was obtained in one step
synthesis involving the titanium trichloride and stoichio-
metric amounts of the lithium salt of the ligand in THF
(Scheme 3), followed by crystallization from pentane.
The C, H, N analysis confirms that the resulting
compound is free from solvent and the lithium salt and
contains two molecules of the ligand only. The melting
Fig. 1. Molecular structure of [(L1)TiCl2]2 (1), hydrogen atoms are
omitted for clarity. Symmetry transformations used to generate
equivalent atoms: ꢃ
/
x, ꢃ
/
yꢂ
/
2, ꢃz.
/
point of 3 is in the range of 82ꢁ84 8C. Complex 3
/
exhibits a signal of the molecular ion [Mꢂ] with the
relative intensity 76%, as well as several intensive peaks
due to the decomposition of the titanium complex
during the EI MS experimental measurements.
Compound 3 is highly soluble in all organic solvents
and is paramagnetic showing strong broadened proton
NMR resonances (Dn1/2 ranged from 50 to 1000 Hz) that
could not be fully interpreted. Compound 3 is sensitive
to air and moisture in the solid state and in solutions.
However, the crystals of 3 can be stored in a glove box
for a long period of time.
A summary of the crystallographic data and refine-
ment parameters for the structure of 3 is given in Table
3. Selected bond lengths and angles are listed in Table 2.
Complex 3 is the first crystallographically determined
Ti(III) b-diketiminato complex with stoichiometry
L2TiCl. Complex 3 crystallizes in the monoclinic space
group P21/c. The X-ray structural analysis revealed that
Fig. 2. Molecular structure of (L1)TiCl(N2,6-i Pr2C6H3) (2), hydrogen
atoms are omitted for clarity.
equivalent and have different chemical shifts. This
indicates that 2 is a rigid complex and stable in solution.
Compounds 1 and 2 are soluble in all common
organic solvents, except in pentane and hexane they
are slightly soluble. Solutions of 1 and 2 in toluene,
THF, Et2O are stable at room temperature and even at
reflux temperature. However, these solutions are sensi-
tive to air and moisture and, therefore, the crystals of 1
and 2 were stored in a glove box.
Scheme 2.

G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ
/2681
2673
compound 3 is monomeric and free from solvent and
lithium salt. In the unit cell are located 2 non-equiv.
molecules of (L2)2TiCl with slightly different geometry
(Table 2; Fig. 3).
over a period of 3 months at 2 8C. Later it was found
that complex 4 can be obtained with a better yield by
reduction of TiCl4 in the presence of (L2)Li salt with
Na/K alloy in THF, followed by crystallization from
pentane (Scheme 3; Fig. 4).
In 3 the N(1)C(1)C(2)C(3)N(2) skeletal atoms are
˚
nearly planar with the deviation of 0.04 A and coordi-
nated to the titanium center through the two nitrogen
The proton NMR spectrum of 4, in C6D6 showed a
set of resonances with a fine structure. The two Me
i
groups of the back bone and the two Pr groups on the
˚
atoms. The titanium atom is 0.98 A out of this plane.
The second ligand has more distorted
N(3)C(6)C(7)C(8)N(4) unit and the deviation from
a
nitrogen atoms are magnetically non-equivalent and
have different chemical shifts. This indicates that 4, like
2, is a rigid complex and stable in solution.
A summary of the crystallographic data and refine-
ment parameters for the structure of 4 is given in Table
3. Selected bond lengths and angles are listed in Table 2.
˚
planarity is 0.104 A. The angle between the two planes
is 19.58. In the second molecule the
N(1a)C(1a)C(2a)C(3a)N(2a) skeletal atoms are also
˚
nearly planar with the deviation of 0.05 A, the titanium
˚
atom is 0.93 A out of this plane. The second
N(3a)C(6a)C(7a)C(8a)N(4a) unit is more distorted and
˚
the deviation from planarity is 0.102 A. The angle
between the two planes is 19.28. The b-diketiminato
ligands coordinate to the metal center through the two
¯
Complex 4 crystallizes in the triclinic P1 space group; X-
/
ray structural analysis revealed that compound 4 is
dimeric in the solid state (Fig. 4).
In complex 4, the almost planar NCCCN units with
˚
the deviation of 0.044 A from planarity are nearly
nitrogen atoms. (Ti(1)ꢀ
2.520(5), Ti(1a)ꢀC(8a) 2.439(5), Ti(1a)ꢀ
A). Although these general features resemble those of
LZrCl3 [1], LSnMe2Cl [1,17] (Lꢀb-diketiminato li-
gands) and [Cp2TiCl]2 [10], the TiꢀC distances of the
latter complexes are significantly shorter (2.332(8)ꢁ
2.373(6) A). The titanium atom is 1.6305 A out of the
N(3)C(6)C(7)C(8)N(4) plane. Two planes of each b-
diketiminato ligand are not parallel, as the angle
between these planes is 19.58.
/
C(6) 2.441(5), Ti(1)ꢀ
/
C(7)
perpendicular to the Ti(m-Cl)2Ti plane that is tilted to
the titanium center with an angle of 103.35(18)8. The b-
/
/
C(7a) 2.536(5)
˚
diketiminato ligands have some p character (Ti(1)ꢀ
/C(1)
˚
C(3) 2.680(3) A). This feature resembles
that of complex 3, as well as those of the Zr(IV) and
/
2.675(4), Ti(1)ꢀ
/
/
/
Sn(IV) b-diketiminato complexes LZrCl3 [5] and
˚
˚
˚
C(1) (2.675(4) A) and
˚
C(3) (2.680(3) A) distances in 4 are significantly
LSnMe2Cl [1,18]. However, Tiꢀ
/
Tiꢀ
/
˚
2.358 A) [20] or
longer than those in Cp2TiCl2 (2.354ꢁ
/
˚
ꢄ
Cp2 TiCl2 (2.346ꢁ
/
2.352) A [21]. The Cꢀ/C bond lengths
The Cꢀ
/
C and Cꢀ/N bond lengths in the NCCCN units
in the NCCCN unit and those between the titanium
atom and the nitrogen atoms in the b-diketiminato
are comparable with those in the stable b-diketiminato
complexes, L2Zr(NMe2)2, L2ZrCl2 [5], {[(L)UCl(NR)(m-
ligand are almost equal. On the other hand, the Cꢀ
/N
Cl)]2}{(L)UCl2(N(R)C(Ph)-NC(Ph)CHR)}2, (Rꢀ
Me3)[18] and LSnMe2Cl [17,1].
N bond lengths are not equal due to different
/
Si-
bond lengths are not equal. Thus, mixed s and p
coordination of the b-diketiminato ligand affects the
The Tiꢀ
/
Cꢀ
/
C and Cꢀ
/
N bonds. The Tiꢀ
/
Cl distances in 4 are
comparable with those in Ti(IV) dimeric complexes with
bonding modes of the nitrogen to titanium atom, but
are comparable with those in the Ti (III) b-diketiminato
two bridging chlorine atoms [LTiCl2(m-Cl)]2 (Ti-(m-Cl)
˚
˚
complex, LTiCl2×
/
2THF (2.087 A; Lꢀ
/(PhNC(Me))2-
2.420; 2.537 A, Lꢀ
/benzamidinato ligand (NSi-
CH), where the Ti is six coordinated. However these
bonds are longer than those in LTiCl2 (1.983(3), 1.986
˚
Me3)2CPh [22]), [LTiCl2(m-Cl)]2 (Ti-(m-Cl) 2.459; 2.564
A, Lꢀ
almost perpendicular to the Ti(m-Cl)2Ti plane, the N(3)ꢀ
Ti(1)ꢀCl(1) angle is 102.94(11)8 and tilted toward the
bridging chlorine atoms. The TiꢁN bond length resem-
/
NH2SiMe2NSiMe2Cl [23]). The (NiPr) unit is
˚
A) with Lꢀ
/
((2,4,6-Me3C6H2)NC(Me))2CH, ((2,4,6-
/
Me3C6H2)NC(tBu))2CH in which the titanium atom is
four coordinated. Also, the TiꢀN bond lengths are
similar to those found for titanium(III) complexes,
/
/
/
bles that in complex 2, but is slightly shorter due to less
˚
[L2TiCl]2 (Tiꢀ
/
N 2.043 and 2.027 A, Lꢀ
/
pyrazolato
bulky substituents on the nitrogen atom.
All evidences indicate that the low valent titanium
˚
ligand [19]; 2.080ꢁ
/
2.12 A, Lꢀ
/
C7H5(NMe2) N,N?-
dimethylaminotroponiminato ligand [13]).
All Ti-bound nitrogen and chlorine atoms are in-
volved in a distorted square pyramidal geometry around
the metal center.
The proton NMR spectrum of the solution of 3
showed a set of relatively sharp resonances in the region
center plays an important role in the cleavage of the Cꢁ
/
N bond of the coordinated diimine ligand. The Ti(III)
oxidized to Ti(IV) and the N(R) group of the ligand
coordinates to the titanium center leading to a Tiꢁ
/N
double bond. Nevertheless, it is possible to handle the
solutions of 3 at low temperatures over a short period
(several days) without appreciable decomposition.
Moreover, the titanium center is deshielded with the
two diimine ligands that are responsible for the solubi-
lity of 3 in all organic solvents. Obviously, the two b-
of 1ꢁ5 ppm due to the decomposition of complex 3 in
/
solution over a period of 3 months. The yellow crystals
of [(L2)TiCl(NiPr)]2 (4), contaminated with viscous oily
material, were obtained from the pentane solution of 3

2674
G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ2681
/
Table 2
powder of 5.
˚
Selected bond lengths (A) and angles (8) for 3, 4 and 6
(L2)2 T iClꢂMe3SnF 1: T0HF r:t: ((L2)TiF2)X
Bond lengths
Bond angles
3
2: pentane
5
CH2Cl2;
0
5 1:
[O ] (L2)4Ti4F6O2 ×2toluene
2
Complex 3
2: toluene
6
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1a)ꢀ
Ti(1a)ꢀ
Ti(1a)ꢀ
Ti(1a)ꢀ
Ti(1a)ꢀ
Ti(1a)ꢀ
Ti(1a)ꢀ
/
N(3)
N(1)
N(2)
N(4)
Cl(1)
C(6)
C(7)
C(8)
2.047(4)
2.057(4)
2.132(4)
2.179(4)
N(3)ꢀ
N(3)ꢀ
N(1)ꢀ
N(3)ꢀ
/
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
N(4a)ꢀTi(1a)ꢀ
N(4a)ꢀTi(1a)ꢀ
N(2a)ꢀTi(1a)ꢀ
N(4a)ꢀTi(1a)ꢀ
N(2a)ꢀTi(1a)ꢀ
N(1a)ꢀTi(1a)ꢀ
N(4a)ꢀTi(1a)ꢀ
N(2a)ꢀTi(1a)ꢀ
N(1a)ꢀTi(1a)ꢀ
N(3a)ꢀTi(1a)ꢀ
/
N(1)
N(2)
N(2)
N(4)
N(4)
N(4)
Cl(1)
Cl(1)
Cl(1)
Cl(1)
141.55(17)
90.81(16)
84.24(17)
80.88(16)
95.23(17)
165.99(15)
116.72(14)
101.72(12)
95.61(12)
98.20(11)
139.99(17)
91.24(16)
84.00(17)
80.82(16)
95.22(17)
166.73(15)
116.98(13)
103.03(12)
95.49(11)
97.59(11)
/
/
/
The reaction product 5 is thermally stable with a
melting point in the range of 205ꢁ207 8C. The identity
/
/
/
/
/
/
/
of this compound containing one ligand with nearly
(L2)TiF2 stoichiometry was determined by its elemental
analysis. Complex 5 exhibits a strong [(L2)TiF2ꢂ] ion, as
well as fragments of [Mꢂ-C3H7F] and [Mꢂ-C5H10N] in
the EI MS spectrum. All attempts to crystallise 5 using
different solvents have failed due to the polymeric
nature of the fluoride complex 5. Solid 5 does not
dissolve at room temperature in toluene, THF and
acetonitrile, but completely dissolves in hot toluene
and benzene. The proton NMR spectrum of 5, in
C6D6, contains resonances that can be assigned to the
b-diketiminato ligand L2 [1e,2c,38]. Four resonances in
the range from 4.6 to 4.2 ppm were assigned to the
protons connected with the central carbon atoms of the
NCCCN units. Four magnetically non-equivalent li-
gands can be present in one complex. Obviously the
polymeric compound 5 decomposes in C6D6 giving
several species. Although 5 dissolves in acetonitrile
upon heating, it produced an amorphous precipitate
whose proton NMR spectrum contained resonances
that can be assigned only to those of the b-diketiminato
ligand L2. We were not able to observe fluorine
resonances of 5 even at low temperature due to the
paramagnetic nature of 5.
/
2.3604(2) N(1)ꢀ
/
/
/
2.441(5)
2.520(5)
2.698(5)
2.034(4)
2.055(5)
2.139(4)
2.187(4)
2.363(2)
2.439(5)
2.536(5)
N(2)ꢀ
N(3)ꢀ
N(1)ꢀ
N(2)ꢀ
N(4)ꢀ
/
/
/
/
/
/
/
/
/
N(4a)
N(2a)
N(1a)
N(3a)
Cl(1a)
C(8a)
C(7a)
/
/
/
/
/
/
/
/
N(2a)
/
/
/
N(1a)
N(1a)
N(3a)
N(3a)
N(3a)
Cl(1a)
Cl(1a)
Cl(1a)
Cl(1a)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Complex 4
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
/
N(3)
N(1)
N(2)
Cl(1)
Cl(1a)
C(1)
1.690(3)
2.046(3)
2.052(2)
2.496(2)
2.516(3)
2.675(4)
2.680(3)
N(3)ꢀ
N(3)ꢀ
N(1)ꢀ
N(3)ꢀ
N(1)ꢀ
N(2)ꢀ
N(3)ꢀ
Cl(1)ꢀ
Ti(1)ꢀ
/
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Cl(1)ꢀ
/
N(1)
N(2)
N(2)
Cl(1)
Cl(1)
Cl(1)
Cl(1a)
108.40(14)
109.07(11)
86.39(9)
/
/
/
/
/
/
/
/
/
102.94(11)
88.95(10)
147.47(6)
102.00(13)
80.62(10)
99.38(10)
/
/
/
/
/
/
/
C(3)
/
/
/
/
Cl(1a)
/
/
Ti(1a)
Complex 6
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(1)ꢀ
Ti(2)ꢀ
Ti(2)ꢀ
Ti(2)ꢀ
Ti(2)ꢀ
Ti(2)ꢀ
Ti(2)ꢀ
Ti(2)ꢀ
/
O(1)
F(1)
1.631(2)
2.017(1)
2.025(1)
2.031(2)
2.049(2)
2.717(2)
1.966(1)
1.986(1)
2.030(1)
2.047(1)
2.071(2)
2.097(2)
3.174(1)
O(1)ꢀ
O(1)ꢀ
F(1)ꢀTi(1)ꢀ
O(1)ꢀTi(1)ꢀ
F(1)ꢀTi(1)ꢀ
F(1)ꢀTi(1)ꢀ
N(2)ꢀTi(1)ꢀ
F(1a)ꢀTi(2)ꢀ
F(3)ꢀTi(2)ꢀF(2)
F(2a)ꢀTi(2)ꢀF(2)
F(1a)ꢀTi(2)ꢀN(3)
F(3)ꢀTi(2)ꢀN(3)
F(2a)ꢀ
F(2)ꢀTi(2)ꢀ
F(3)ꢀTi(2)ꢀ
F(2)ꢀTi(2)ꢀ
N(3)ꢀTi(2)ꢀ
F(1a)ꢀTi(2)ꢀ
Ti(2a)ꢀF(1)ꢀ
Ti(2a)ꢀF(2)ꢀ
/
Ti(1)ꢀ
Ti(1)ꢀ
/F(1)
110.21(9)
102.44(8)
83.42(5)
104.95(8)
84.71(7)
142.06(7)
85.12(8)
165.27(5)
87.38(6)
77.75(6)
99.31(7)
92.98(7)
170.20(7)
92.85(7)
99.12(7)
172.94(7)
89.61(8)
81.36(4)
147.47(7)
102.25(6)
Evaporation of CH2Cl2 solution of 5 gave a viscous
residue. Recrystallization of this residue from toluene
afforded green crystals of the tetranuclear complex
/
/
/F(3)
/
F(3)
/
/
F(3)
/
N(2)
N(1)
C(3)
F(1a)
F(3)
/
/
N(2)
N(2)
N(1)
/
/
/
(L2)4Ti4F6O2×
/2toluene (6) with two terminal oxygen
/
/
/
atoms coordinated to the two titanium atoms. Although
the nature of the oxygen is not exactly known (H2O,
air), 6 has been characterized thoroughly, including X-
ray analysis.
/
/
/N(1)
/
/
/
F(3)
/
F(2a)
F(2)
/
/
/
/
/
/
N(3)
N(4)
Ti(2a)
/
/
A summary of the crystallographic data and refine-
ment parameters for 6 are given in Table 3. Selected
bond lengths and angles are listed in Table 2.
Complex 6 crystallizes in the monoclinic space group
P21/n. The crystal structure of 6 (Fig. 5) shows a
/
/
/
/
/
Ti(2)ꢀ
/
N(3)
/
/
N(3)
N(4)
N(4)
/
/
/
/
/
/N(4)
tetranuclear complex (L2)4Ti4F6O2×
/2toluene that con-
/
/
Ti(2a)
Ti(1)
Ti(2)
tains two (L2)Ti and two (L2)TiO units connected via
bridging fluorine atoms. This complex can formally be
described as a mixed Ti(III)/Ti(IV) fluoride complex. A
part of the inorganic core, Ti(1){m-F}2Ti(2)Ti(2a){m-
F}2Ti(1a), is almost planar with two terminal oxygen
atoms and two bridging fluorine atoms F(2) and F(2a)
that are out of this plane (Fig. 5). While the angle
/
/
/
/
diketiminato ligands (L2) stabilize the titanium(III)
chloride complex.
Interaction of 3 with 1 equiv. of Me3SnF in THF
affords a clear solution. After evaporation of the
solvent, the residue was extracted with pentane and
the resulting pentane solution gave the dark green
between F(1)ꢀ
fluorine atoms F(2) and F(2a) are located between the
Ti(2) and Ti(2a) atoms above and below the plane so
/
TiꢀO(1) is 110.21(9)8, the two bridging
/

G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ
/2681
2675
Scheme 3. Synthesis of complexes 3 and 4.
Fig. 3. Molecular structure of (L2)2TiCl (3), hydrogen atoms are
omitted for clarity.
that the F(2)ꢀ
The geometry of the inorganic core in 6 differs from
those in known tetranuclear Ti(III) complexes
/
F(2a) line is perpendicular to this plane.
Fig. 4. Molecular structure of [(L2)TiCl(Ni Pr)]2 (4), hydrogen atoms
are omitted for clarity. Symmetry transformations used to generate
equivalent atoms: ꢃ
/
xꢂ
/
1, ꢃ
/
y, ꢃz.
/
Scheme 4.

2676
G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ2681
/
Table 3
Crystallographic data of the X-ray diffraction studies of compounds 1, 4 and 6
1
2
3
4
6
Empirical formula
Mr
C
536.44
29H41Cl2N2Ti
C41H58ClN3Ti
676.25
133(2)
C22H42ClN4Ti
445.95
270(2)
C14H28ClN3Ti
321.74
153(2)
C29H50F3N4OTi2
623.53
133(2)
Temp (K)
133(2)
Mo Ka (0.71073)
green plates
˚
Radiation used (l(A))
Crystal description
Crystal size (mm)
Crystal system
Mo Ka (0.71073)
red needles
Mo Ka (0.71073)
dark green blocks
1.00ꢅ0.60ꢅ0.50
Mo Ka (0.71073)
yellow blocks
Mo Ka (0.71073)
green plates
0.8ꢅ
/
0.8ꢅ
/
0.2
1.00ꢅ/0.10ꢅ/0.10
/
/
0.80ꢅ/0.80ꢅ/0.70
0.8ꢅ
/
0.8ꢅ0.10
/
monoclinic
P21/n
monoclinic
P21/n
8.9426(18)
24.116(5)
17.949
90
monoclinic
P21/c
triclinic
¯
P1
monoclinic
P21/n
Space group
˚
/
a (A)
˚
13.792(3)
13.584(3)
15.693(3)
90
9.4490(2)
15.045(3)
35.357(7)
90
9.302(9)
9.504(11)
11.124(11)
98.96(11)
107.07(4)
104.94(4)
879.40(15)
1
15.307(3)
13.094(3)
16.856(3)
90
b (A)
˚
c (A)
a (8)
b (8)
g (8)
105.42(3)
90
92.02(3)
90
93.84(3)
90
105.06(3)
90
3
˚
V (A )
2834.4(10)
4
1140
3868.5(13)
4
1456
5015.0(17)
8
1928
3262.3(11)
4
1324
Z
F (0 0 0)
rcalc (g cmꢃ3
344
1.215
)
1.257
0.510
1.161
0.321
1.181
0.462
1.270
0.533
m (mmꢃ1
)
0.631
3228
Total reflections
Unique reflections
Rint
15 516
4827
0.0663
9155
4179
15 219
8728
0.0942
52 241
5634
0.0739
3062
0.0572
0.1331
Scan range u (8)
Completeness to umax (%)
Index ranges
1.75ꢁ
98.2
165
12ꢀ
18ꢀ
4827/0/317
/
24.86
1.41ꢁ
85.5
8ꢀ
25ꢀ
18ꢀ
4179/1/415
/
22.23
3.54ꢁ
98.6
11ꢀ
17ꢀ
42ꢀ
8728/0/530
/
25.02
3.54ꢁ
98.8
11ꢀ
11ꢀ
10ꢀ
3062/0/184
/
25.00
1.60ꢁ
99.5
18ꢀ
15ꢀ
19ꢀ
5634/0/365
/
24.88
ꢃ
/
/
h 5
kꢀ
lꢀ
/
16,
ꢃ
/
/
hꢀ
kꢀ
lꢀ12
/
9,
ꢃ
/
/
hꢀ
kꢀ
lꢀ42
/
11,
ꢃ
/
/
hꢀ
kꢀ
lꢀ13
/
11,
ꢃ
/
/
hꢀ
kꢀ
lꢀ19
/
18,
ꢃ
/
/
/
15,
ꢃ
/
/
/
25,
ꢃ
/
/
/
17,
ꢃ
/
/
/
11,
ꢃ
/
/
/
15,
ꢃ/
/
/
18
ꢃ/
/
/
ꢃ/
/
/
ꢃ/
/
/
ꢃ/
/
/
Data/restraints/parameters
R1 a b, wR2 [I ꢀ
/
2s(I)] c
0.0476, 0.1119
0.0679, 0.1172
full-matrix least-
squares on F2
0.919
0.0654, 0.1264
0.1629, 0.1548
full-matrix least-
squares on F2
0.810
0.0736, 0.1805
0.0962, 0.1936
full-matrix least-
squares on F2
1.197
0.0445, 0.1232
0.0468, 0.1262
full-matrix least-
squares on F2
1.003
0.0375, 0.0958
0.0520, 0.0993
full-matrix least-
squares on F2
0.893
R1 a d, wR2 (all data) c d
Refinement method
Goodness-of-fit on F2 e
˚
Max./min. el. dens. (e A
ꢃ3
)
0.812, ꢃ
/
0.721
0.373, ꢃ
/
0.224
0.742, ꢃ
/
0.517
0.988, ꢃ
/
0.500
1.291, ꢃ0.331
/
a
R1ꢀ
/
SjFojꢃ
Denotes the value of the residual considering only the reflections with I ꢀ
wR2ꢀ bP], Pꢀ
{S[w(Fo2ꢃFc2)2]/S[w(Fo2)2]}1/2; wꢀ1/[S2(Fo2)2ꢂ(aP)2ꢂ [max(Fo2 or 0)ꢂ
Denotes the value of the residual considering all the reflections.
Sꢀ
[S[w(Fo2ꢃFc2)2]/[(nꢃp)1/2], n, number of data; p, parameters used.
/
jFcj/SjFoj.
b
c
/2s(I).
/
/
/
/
/
/
/
2(Fc2)/3].
d
e
/
/
/
{[C5H4(SiMe3)]2TiF2}3M (Mꢀ/Ti [24], Ga [24], Al [25]).
The two titanium atoms Ti(1) and Ti(1a) are coordi-
However, no tetranuclear Ti(IV) fluoride complexes
are known for comparison. Nonetheless, trinuclear
nated to the two bridging fluorine atoms, terminal
oxygen and nitrogen atoms of the b-diketiminato ligand.
The NCCCN planar moieties of this b-diketiminato
ligands are almost perpendicular to the inorganic plane
and
hexanuclear
Ti(IV)
fluoride
complexes,
1.5CH3CN [26],
[TiF3(m-Ph2PO2)3Ti(m-Ph2PO2)3TiF3]×
/
ꢄ
Cp4Ti4Zn2Me2F14 [33] have been structurally character-
ized.
Ti(1){m-F}2Ti(2)Ti(2a){m-F}2Ti(1a). The short Cꢀ
/
Ti
˚
distances (2.717(5) A) indicate a partial p coordination
of the NCCCN unsaturated system to the titanium
center as in 3 and 4. The Ti(1)-{m-F} distances in 6
are similar to those in Ti(IV) complexes, but differ
Each titanium atom of the inorganic Ti4F6O2 unit is
coordinated to the b-diketiminato ligand, thus providing
its partial solubility in hydrocarbon solvents.
The Ti(1)ꢀ
N distances due to smaller ionic radius of the Ti(IV)
compared to that of the Ti(III) ion. The TiꢀN bond
lengths in 6 have different values for four coordinated
ligands, similar to those in 1ꢁ4, due to a different
donorꢁacceptor bond character in the complex. The
/
N distances in 6 are shorter than the Ti(2)ꢀ
/
marginally from the corresponding distances in
˚
[(C5H4Me)TiF3]2×(THF) (Ti-{m-F} 2.022 A) [27]. The
/
/
Tiꢀ
/
O bond distance in 6 is similar to the titaniumꢁ
/
oxygen double bond length in complexes LTi(O)(NCS)2
˚
/
(Tiꢁ
/
O 1.638 [28] A), Lꢀ1,4,7,-trimethyl-1,4,7 triazacy-
/
˚
/
clononane; L2Ti(O)OPy (1.654 [29] A), Lꢀbenzamidi-
/
1
2
1
˚
toluene molecules are not coordinated to any titanium
center; they occupy vacant lattice sites.
nate ligand; (L )(L )Ti(O) (1.657 [30] A), L ꢀ
/2,6-
diisopropylphenoxide, L2ꢀ
/
4-pyrrolidinopyridine.

G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ
/2681
2677
Specifically, the proton NMR spectra of 6 exhibited
resonances of [(L2)TiF2] and [(L2)TiFO] units, in
addition to other resonances that do not correspond to
6. Therefore, it is reasonable to assume that the
tetrameric compound 6 decomposes in C6D6 leading to
several species containing the b-diketiminato ligand.
3. Conclusions
We have prepared and characterized the Ti(III)
complexes, (L1)TiCl2 (1), (L2)2TiCl (3) and the
Ti(IV) complexes, (L1)TiCl(N2,6-iPr2C6H3) (2),
[(L2)TiCl(NiPr)]2 (4) with the b-diketiminato ligands
(L1), (L2). The titanium b-diketiminato complexes, 1, 2
and 3, have been obtained by the direct reaction of the
lithium salt of the ligand with the titanium trichloride.
The monochloride complex {[(L1)2TiCl} is not isolable
from the supernatant solutions with the excess (L1)Li
salt, but by means of the mass spectrometry, the
Fig. 5. Molecular structure of (L2)4Ti4F6O2×
atoms are omitted for clarity. Symmetry transformations used to
generate equivalent atoms: ꢃxꢂ2, ꢃyꢂ1, ꢃz.
/
toluene (6), hydrogen
/
/
/
/
/
The Ti(2) and Ti(2a) atoms are bonded to two
different kinds of bridging fluorine atoms and to the
fragment [(L1)2TiClꢂ ꢁ
C12H17] of this complex was
/
nitrogen atoms of the b-diketiminato ligand. The Ti(2)ꢀ
{m-F(2)} bond lengths are longer than Ti(2)ꢀ{m-F(1)},
Ti(2)ꢀ{m-F(3)} bonds. The Ti(2)ꢀ{m-F} bond lengths
are similar to Tiꢀ{m-F}distances in Ti(III) clusters,
/
/
detected; the final product of the reaction of TiCl3
with excess of (L1)Li was complex 2. With the less bulky
ligand it was possible to isolate 3, but the latter
compound is unstable and slowly decomposed with the
/
/
/
˚
ꢄ
Cp12Ti14Na18F48(THF)6 (short Tiꢀ
/
F 1.98 A, long Tiꢀ
/
˚
˚
F 2.06 A) [31]
˚
F 2.046 A) [32]. The
F 2.05 A), (Cp*TiF2)6CaF2(THF)2 (Tiꢀ
and Cp6 Ti6Na7F19×
/
cleavage of the CꢀN double bond of the coordinated b-
/
ꢄ
/
2.5(THF) (Tiꢀ
/
diketiminato ligand. The Ti(III) is oxidized to Ti(IV)
and the N(R) group of the ligand coordinated to
coordination number of the titanium atoms, Ti(2) and
Ti(2a), in 6 is six with the four bridging fluorine atoms
and two nitrogen atoms of the b-diketiminato ligand
that form a distorted octahedral geometry about the
metal atom.
the titanium center giving complex 4 with Tiꢀ
/
N
double bond. The bulky ligand
L1ꢀ
/
(2,6-iPr2C6H3)NC(Me)CHC(Me)N(2,6-iPr2C6H3) stabi-
lizes the dimeric Ti(III) complex with the unusual
coordination of the titanium atom, in which the
ligand is s-bonded to the titanium atom with the
coordination number of 5. The less bulky ligand,
The distance between the Ti(2) and Ti(2a) atoms in 6
is the shortest Tiꢀ
bonding distance. The Ti(2)ꢀ
similar to the TiꢀTi distance in the Ti(IV) polynuclear
fluoride complex, Cp4Ti4(ZnMe)2F14 (Tiꢀ
[33], in the Ti(III) complexes, Cp2LTi2HCl (Lꢀ
lene), with bridging chlorine and hydrogen atoms (Tiꢀ
/Ti contact and can be described as a
/Ti(2a) bond length is
L2ꢀi
and 6 has mixed s- and p-coordination to the titanium
center. Comparison of the CꢀC, NꢀC distances in the
/
PrNC(Me)CHC(Me)NiPr in the complexes 3, 4
/
˚
ꢄ
/
Ti 3.007 A)
fulva-
Ti
3.128 A) [34] and {Cp(m-[h :h -C5H4])Ti(PMe3)}2 (Tiꢀ
/
/
/
/
NCCCN asymmetric unit of the coordinated b-diketi-
minato ligand demonstrated that the localization of the
1
5
˚
/
˚
Ti 3.222 A) [35] and in the tetranuclear Ti(III) complex
double bonds is significant in complexes 1ꢁ3 and 6, as in
/
with bridging sulfur atoms, (C5H4Me)4Ti4S4 (TiꢀTi
/
(L1)H (Schemes 2 and 4). The solid state structure of
Ti(IV) complexes 2 and 4 is also present in C6D6
solution as confirmed by their proton NMR spectra. It
is shown that Me3SnF is an appropriate fluorination
reagent for the non-metallocene Ti(III) compound (3),
but the basicity of the ligand L2 was not enough to
stabilize the Ti(III) fluoride complex. Fluorination of
the monochloride complex 3 afforded a polymeric
substance, [(L2)4TiF2]n (5). Oxidation of 5 gave a
˚
3.007 A) [36].
Complex 6 is more thermally stable than 5, with the
melting point of 238ꢁ240 8C. The signals of the
/
[(L2)TiFOꢂ] ion and its fragments as well as those for
the [(L2)TiF2ꢂ] unit and its fragments were observed in
the EI-mass spectra of 6. Compound 6 is insoluble in
C6D6 and toluene at r.t., but dissolves upon heating. The
proton NMR spectrum of 6, in C6D6, exhibits reso-
nances due to different species containing the b-diketi-
minato ligand L2. For the interpretation of the 1H
NMR spectrum of 6, the resonances of compound
(L2)H [37] and complex 5 were also taken into account.
tetrameric complex, L4Ti4F6O2×/2toluene (6), which can
formally be described as a mixed Ti(III)/Ti(IV) fluoride
complex. Thus, this work clearly demonstrates that the

2678
G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ2681
/
solid state structures of 5 and 6 are not present in C6D6
solution.
second portion of crystals was obtained from this
filtrate. Yield: 3.10 g (65%). C29H41Cl2N2Ti: Calc. C
64.93, H 7.65, N 5.22; Found: C 64.90, H 7.70, N 5.18%.
M.p. 174ꢁ
521 (2) [Mꢂ-CH4], 500 (2) [Mꢂ-C12H17]. 1H NMR (200
MHz, C6D6, r.t.), dꢀ 5 (Dv1/2 800 Hz), 0.81 (d,;>
24H, Jꢀ6.0 Hz, CHMe2), 0.95 (24H, CHMe2), 1.16 (d,
24H, Jꢀ6.5 Hz, CHMe2), 1.24 (d, 24H, Jꢀ8.5 Hz,
/
176 8C. EI MS: m/z (%)ꢀ
/
535 (100) [Mꢂ],
4. Experimental
/
ꢃ
/
4.1. General procedures and starting materials
/
/
/
All operations were performed using standard
Schlenk line and dry box techniques under purified
nitrogen and argon atmosphere. Water-free titanium
trichloride used was of commercial reagent quality
(purity 99.99%). The compounds LH with the ligands
CHMe2), 1.3 (Dv1/2 95 Hz), 1.4 (24H, CHMe2) 1.6 (24H,
CHMe2), 1.70 (s, 6H, Me), 2.0 (s, 6H, Me), 2.2 (Dv1/2 54
Hz) 2.9 (Dv1/2 64 Hz), 3.25 (sept, 4H, Jꢀ
CHMe2), 4.4 (Dv1/2 96 Hz), 4.83 (s, 1H, g-CH), 5.7
(Dv1/2 80 Hz), 6.3 (Dv1/2 223 Hz), 6.6ꢁ7.6 (m, 6H,
C6H3) ppm.
/6.5 Hz,
/
L1ꢀ
/
(2,6-iPr2C6H3NC(Me))2CH, L2ꢀ(iPrNC(Me))2-
/
CH were prepared by the known literature methods
[5d,37,38]. The purity of LH was checked by the
The dark-brown pentane solution A was filtered and
concentrated. Finally, the resulting pentane solution was
1
elemental analysis, H and 13C NMR spectra. Me3SnF
left at 2 8C to produce big colorless crystals of (L1)Li×
/
was prepared by the literature method [39]. The purity
of Me3SnF was checked by elemental analysis, the
product contains less than 1% of chlorine. While
toluene, pentane and THF were dried over Na/benzo-
phenone and distilled under nitrogen prior to use, C6D6
and [D8] THF were dried over Na and degassed and
CD2Cl2 was dried over CaH2 and degassed. Proton
NMR spectra were recorded using Bruker AM 200
NMR spectrometer. Chemical shifts are reported in d
units downfield from Me4Si with the solvent as the
reference signal. Mass spectra were recorded using a
Finnigan MAT 8230 mass spectrometer, and elemental
analysis were carried out at the Analytical Laboratories
of the Institute of Inorganic Chemistry at the University
THF (0.6 g) that were separated by filtration.
C33H51LiN2O Calc. C 79.52, H 10.24, N 5.62; Found:
C 79.60, H 10.31, N 5.68%. The 1H and 13C NMR
spectra are identical to those reported earlier for (L1)Li×
/
THF [6]. Crystallographic data are also consistent with
those in the literature [6,7]: space group monoclinic P21/
˚
˚
˚
n, aꢀ
/
9.54 A, bꢀ
/
17.91 A, cꢀ
/
21.71 A, bꢀ
/
95.48, Vꢀ
/
3
3694 A .
˚
The dark-brown pentane solution after removing the
(L1)Li salt by filtration was left undisturbed at 2 8C.
After 14 days small red crystals, covered with viscous
mass, were separated from the pentane solution. EI MS:
m/z (%)ꢀ
599 (6) [(L1)2TiClꢂꢃ
(C12H17)2], 535 (8) [(L1)2Tiꢂꢃ
[Mꢂꢃ
NC12H17].
/
758 (44) [(L)2TiClꢂꢃ
(C12H17)2], 564 (10) [(L1)2Tiꢂꢃ
(NC12H17)2], 500 (100)
/
C12H17], 675 (3) [Mꢂ],
/
/
of Gottingen. Melting points were measured in sealed
¨
capillary tubes under nitrogen and are not corrected.
/
/
Red crystals that are appropriate for X-ray analysis
were obtained from the pentane solution after 3 months.
Yield of 2 (0.42 g, 7%). C41H58ClN3Ti: Calc. C 72.84, H
8.59, N 6.22; Found: C 72.90, H 8.66, N 6.17%. M.p.
4.2. Reaction of (L1)Li with TiCl3 in THF. Synthesis of
(L1)TiCl2 (1) and (L1)TiCl(N(2,6-iPr)2C6H3) (2)
97ꢁ
[Mꢂꢃ
NC12H17]. H NMR (200 MHz, C6D6, r.t.), dꢀ
(d, 12H, Jꢀ3.0 Hz, CHMe2), 1.20 (d, 24H, Jꢀ3.9 Hz,
CHMe2), 1.57 (s, 3H, Me), 1.68 (s, 6H, Me), 2.95 (sept,
4H, Jꢀ6.5 Hz, CHMe2), 3.33 (sept, 2H, Jꢀ6.8 Hz,
CHMe2), 4.81 (s, 1H, g-CH), 6.6ꢁ7.2 (m, 6H, C6H3)
/
98 8C. EI MS: m/z (%)ꢀ
CH3], 632 (1) [MꢂꢃC3H7], 500 (100) [Mꢂ
1.17
/
675 (34) [Mꢂ], 660 (5)
Dry THF (50 ml) was added to the compound (L1)H
(3.75 g, 9.0 mmol) in a 100 ml Schlenk flask. The
/
/
1
mixture was cooled to ꢃ78 8C and to this a solution of
/
ꢃ
/
/
5.62 ml (1.6 M, 9.0 mmol) LiMe in Et2O was added
dropwise. The reaction mixture was stirred for 1 h at
/
/
ꢃ78 8C, allowed to warm to room temperature and
/
/
/
stirred until methane evolution had ceased. This solu-
tion was added dropwise to a suspension of TiCl3 (1.39
g, 9.0 mmol) in THF (120 ml) at r.t. in a 200 ml Schlenk
flask. Subsequently, the reaction mixture was stirred for
6 days at r.t. The resulting suspension was filtered, THF
removed under vacuum, and the green residue washed
portion wise (15 mled by heating in toluene (150 ml) and
allowed to stand 7 days at room temperature, when a
white powder (LiCl) separated from a clear green
solution. The solution was filtered and concentrated to
50 ml. The green crystals were separated by filtration. A
/
ppm.
4.3. Preparation of (L2)2TiCl (3)
Compound (L2)H (1.41 g, 1.57 ml, 7.8 mmol) was
added to dry THF (30 ml) in a 50 ml Schlenk flask. The
mixture was cooled to ꢃ78 8C and to this a solution of
/
4.85 ml (1.6 M, 7.8 mmol) LiMe in Et2O was added
dropwise. The reaction mixture was stirred for 1 h at
ꢃ78 8C, allowed to warm to r.t. and stirred until
/

G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ
/2681
2679
methane evolution had ceased. The resulting solution
was added dropwise to a suspension of TiCl3 (0.6 g, 3.9
4.4.1. Alternative method
Solution of 3 (1 g, 2.2 mmol) in pentane (10 ml) was
kept at 2 8C for 1 month. From this solution small
yellow crystals, covered with a film of a viscous oil, were
mmol) in THF (30 ml) at ꢃ79 8C in a 100-ml Schlenk
/
flask, allowed to warm to room temperature and stirred
at this temperature for 2 h. THF was removed in vacuo,
and the residue extracted with pentane (60 ml). The
green pentane solution was allowed to stand overnight
at r.t., during which time a white powder (LiCl)
separated out of a clear yellow solution and was
removed by filtration, and the filtrate was concentrated
obtained. M.p. 112ꢁ
/
114 8C. EI MS: m/z (%)ꢀ
/
831 (100)
[M2ꢂꢃC3H7N], 42 (10) [C3H6]ꢂ. The crystals that are
/
sufficient for characterization were grown during the 3
month period from the pentane solution of 3. These
crystals were washed with pentane and dried in vacuo.
The analytical data for the colorless crystals are
consistent with those of 4.
(5ꢁ
/
7 ml). The concentrated solution was left undis-
24 8C. Finally, dark-green crystals
turbed for 2 days at ꢃ
/
4.5. Reaction of (L2)2TiCl with Me3SnF in THF,
preparation of (5)
formed, which were separated by filtration and dried in
vacuo. Yield of 3 1.47 g (85.0%). C22H42ClN4Ti: Calc. C
59.26, H 9.43, N 12.57; Found: C 59.31, H 9.47, N
A mixture of 3 (1.4 g, 3.1 mmol) and Me3SnF (0.57 g,
3.1 mmol) in a 100 ml Schlenk flask in THF (40 ml) was
stirred until all the solid dissolved (12 h). All volatiles
were removed under vacuum, and the residue extracted
with pentane (20 ml). This solution was left undisturbed
for 7 days at r.t. The resulting dark-green powder was
separated by filtration and washed with pentane (3 ml).
Another crop of this dark-green powder was obtained
from the supernatant pentane solution. Yield of
[(L2)TiF2] 5 (0.38 g, 90%). C11H21F2N2Ti: Calc. C
49.44, H 7.87, N 10.49; Found: C 49.14, H 7.78, N
12.51%. M.p. 82ꢁ
/
84 8C. EI MS: m/z (%)ꢀ
CH4], 404 (14) [Mꢂꢃ
C3H7], 383
C2H5Cl]. H NMR (200 MHz, C6D6, r.t.),
0.9 (Dv1/2 45 Hz), 1.1 (12H CHMe2), 1.3 (12H,
/
445 (76)
[Mꢂ], 426 (8) [Mꢂꢃ
/
/
(7) [Mꢂꢃ
dꢀ
/
1
/
CHMe2), 1.5 (12H, CHMe2), 1.7 (6H, Me), 1.8 (Dv1/2
143 Hz), 3.5 (2H, CHMe2) 3.8 (2H, CHMe2), 4.2 (1H,
g-CH), 4.5 (1H, g-CH) ppm.
4.4. Preparation of [(L2)TiCl(NiPr)]2 (4)
10.15%. M.p. 205ꢁ
/
207 8C. EI MS: m/z (%)ꢀ528 (3)
/
[M2F2ꢂꢃ
/
C3H7], 508 (2) [M2Fꢂꢃ
C3H7], 486 (1)
/
Compound (L2)H (2.32 g, 2.58 ml, 12.7 mmol) was
added to dry THF (30 ml) in a Schlenk flask (50 ml).
[M2F2ꢂꢃ
/
C5H10N], 449 (1) [M2ꢂ-C5H10N], 394 (8)
[M2ꢂ-C8H17N2]. H NMR (200 MHz, C6D6, r.t.), dꢀ
/
1
The mixture was cooled to ꢃ
of 8.0 ml (1.6 M, 12.7 mmol) LiMe in Et2O was added
dropwise. The reaction mixture was stirred for 1 h at ꢃ
/
78 8C and to this a solution
1.10 (d, 12H, Jꢀ
Hz, CHMe2), 1.37 (d, 12H, Jꢀ
12H, Jꢀ7.9 Hz, CHMe2), 1.48 (12H, CHMe2), 1.71 (s,
/
6.2 Hz, CHMe2), 1.22 (d, 12H, Jꢀ
/4.8
/
/
6.8 Hz, CHMe2), 1.44 (d,
78 8C, allowed to warm to r.t. and stirred until methane
evolution had ceased. The resulting solution was added
dropwise to a solution of TiCl4 (1.21 g, 0.7 ml, 6.35
/
6H, Me), 1.84 (12H, CHMe2), 2.05 (s, 6H, Me), 2.21 (s,
6H, Me), 3.10 (s, 6H, Me), 3.37 (s, 6H, Me), 3.46 (2H,
CHMe2), 3.52 (2H, CHMe2), 4.50 (s, 1H, g-CH), 4.58
(s, 1H, g-CH), 4.88 (s, 1H, g-CH), 5.26 (s, 1H, g-CH)
ppm.
mmol) in THF (30 ml) at ꢃ79 8C in a 100-ml Schlenk
/
flask, stirred for 1 h and allowed to warm to r.t. and
stirring was continued for 2 h at this temperature.
Finally Na/K alloy (0.841 g, K 18.9 mmol, Na 3.6
mmol) was added via syringe and the resulting mixture
was rigorously stirred for 4 days at r.t. THF was
removed under vacuum, and the residue extracted with
pentane (60 ml). The dark-green pentane solution was
filtered and concentrated to 15 ml. The resulting
solution was left undisturbed for 3 months at 2 8C.
Finally, big yellow crystals formed, that were separated
by filtration, washed with pentane and dried in vacuo.
Yield of 4 0.67 g (33%). C14H28ClN3Ti: Calc. C 52.26, H
8.71, N 13.06; Found: C 52.31, H 9.76, N 13.01%. M.p.
4.6. Synthesis of (L2)4Ti4F6O2×
/
2toluene (6)
Compound 5 (0.4 g) was dissolved in CH2Cl2 (15 ml)
in a Schlenk flask (100 ml). A second Schlenk flask (100
8ml) filled with toluene (15 ml) was connected via the
glass filter to the first flask containing the solution of 5.
The system was kept undisturbed at 2 8C. After 10 days
all CH2Cl2 evaporated into the flask containing the
toluene. The resulting residue is a viscous mass. To this
mass fresh toluene (7 ml) was added and the solution
was left at r.t. Oxygen gas for the oxidation of 5 was
slowly diffused through the pinch hole in the stopper
during 12 days. The green crystals, formed after 12 days,
were separated by filtration, washed with pentane (3 ml)
and dried in vacuo. Yield of (L2)4Ti4F6O2 (0.18 g, 45%).
C11H21F1.5N2O0.5Ti: Calc. C 49.72, H 7.91, N 10.55;
112ꢁ
[Mꢂꢃ
MHz, C6D6, r.t.), dꢀ
CHMe2), 1.41 (d, 3H, Jꢀ
3H, Jꢀ3.9 Hz, CHMeMe), 1.71 (s, 6H, Me), 3.47 (sept,
2H, Jꢀ6.2 Hz, CHMe2), 3.6 (m, 1H, CHMeMe), 4.49
(s, 1H, g-CH) ppm.
/
114 8C. EI MS: m/z (%)ꢀ
CH4], 278 (41) [Mꢂꢃ
1.12 (d, 12H, Jꢀ
3.0 Hz, CHMeMe), 1.45 (d,
/
321 (100) [Mꢂ], 306 (45)
C3H7]. 1H NMR (200
6.3 Hz,
/
/
/
/
/
/
/
Found: C 49.24, H 8.01, N 10.21%. M.p. 238ꢁ240 8C.
/

2680
G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ2681
/
J.C. Calabrese, S.D. Arthur, Organometallics 16 (1997) 1514;
(c) N. Kuhn, A. Kuhn, R. Boese, N. Augart, J. Chem. Soc.,
Chem. Commun. (1989) 975;
EI MS: m/z (%)ꢀ
C3H7], 528 (19) [((L2)TiF2)2F2ꢂꢃ
[((L2)TiF2)2FꢂꢃC3H7], 486 (5) [((L2)TiF2)2F2ꢂ
C5H10N], 450 (6) [((L2)TiF2)2ꢂꢃ
C5H10N], 388 (2)
[((L2)TiF2)2FꢂꢃC11H21N], 347 (38) [((L2)TiF2)2ꢂ
C11H21NF], 267 (100) [(L2)TiF2ꢂ], 264 (28)
[(L2)TiFOꢂ]. 1H NMR (200 MHz, C6D6, r.t.),
dꢀ1.10 (d, 12H, Jꢀ6.3 Hz, CHMe2), 1.20 (12H,
CHMe2), 1.23 (s, 3H, Me, toluene), 1.35 (d, 12H,
Jꢀ5.8 Hz, CHMe2, LTiO unit), 1.50 (12H, CHMe2),
/
589 (2) [((L2)TiFO)2TiN2C2H3ꢂ
C3H7], 508 (10)
ꢃ
/
/
/
(d) J. Prust, H. Hohmeister, A. Stasch, H.W. Roesky, J. Magull,
E. Alexopoulos, I. Uso´n, H.-G. Schmidt, M. Noltemeyer, Eur. J.
Inorg. Chem. (2002) 2156;
ꢃ
/
/
/
(e) J. Prust, K. Most, I. Muller, A. Stasch, H.W. Roesky, I. Uso´n,
¨
Eur. J. Inorg. Chem. (2001) 1613;
ꢃ
/
(f) Y. Ding, H.W. Roesky, M. Noltemeyer, H.-G. Schmidt, P.P.
Power, Organometallics 20 (2001) 1190;
/
/
(g) L.W.M. Lee, W.E. Piers, M.R.J. Elsegood, W. Clegg, M.
Parvez, Organometallics 19 (1999) 2947;
/
1.71 (s, 6H, Me), 1.84 (12H, CHMe2), 2.10 (s, 6H, Me),
3.10 (s, 6H, Me), 3.34 (s, 6H, Me), 3.36 (2H, CHMe2),
3.42 (2H, CHMe2), 3.47 (2H, CHMe2), 4.49 (s, 1H, g-
CH), ppm.
(h) P.J. Bailey, C.M.E. Dick, S. Fabre, S. Parsons, J. Chem. Soc.,
Dalton Trans. (2000) 1655;
(i) V.C. Gibson, J.A. Segal, A.J.P. White, D.J. Williams, J. Am.
Chem. Soc. 122 (2000) 7120;
(j) C.E. Radzewich, I.A. Guzei, R.F. Jordan, J. Am. Chem. Soc.
121 (1999) 8673;
4.7. X-ray crystallographic study
(k) P.B. Hitchcock, M.F. Lappert, D.S. Liu, J. Chem. Soc., Chem.
Commun. (1994) 2637.
[2] (a) C. Cui, H.W. Roesky, H.-G. Schmidt, M. Noltemeyer, H.
Hao, F. Cimpoesu, Angew. Chem. 112 (2000) 4444;
(b) C. Cui, H.W. Roesky, H.-G. Schmidt, M. Noltemeyer, H.
Hao, F. Cimpoesu, Angew. Chem., Int. Ed. 39 (2000) 4274;
(c) N.J. Hardman, B.E. Eichler, P.P. Power, Chem. Commun.
(2000) 1991;
Crystal data and experimental conditions are listed in
Table 3. Selected bond lengths and bond angles with
standard deviations in parentheses are presented in
Tables 1 and 2. Intensity data for the crystal structures
of (L1)TiCl2, (L1)TiCl(N2,6iPrC6H3) and (L2)4-
(d) A.M. Neculai, D. Neculai, H.W. Roesky, J. Magull, M.
Baldus, O. Andronesi, M. Jansen, Organometallics 21 (2002)
2590.
Ti4F6O2×
/
2toluene were collected on a Stoe image plate
IPDS II-system. Data for the crystal structure of
[(L2)TiCl(NiPr)]2 and (L2)2TiCl were collected on a
[3] P.B. Hitchcock, M.F. Lappert, S. Tian, J. Chem. Soc., Dalton
Trans. (1997) 1945.
StoeꢁSiemens four-circle diffractometer. All structures
/
were solved by direct methods (SHELXS-97) and refined
against F2 using SHELXS-97 [40]. The heavy atoms were
refined anisotropically. Hydrogen atoms were included
using the riding model with Uiso tied to Uiso of the
parent atoms.
[4] M. Stender, A.D. Phillips, P.P. Power, Inorg. Chem. 40 (2001)
5314.
[5] (a) M. Rahim, N.J. Taylor, S. Xin, S. Collins, Organometallics 17
(1998) 1315;
(b) B. Qian, D.L. Ward, M.R. Smith, Organometallics 17 (1998)
3070;
(c) B. Qian, S.W. Baek, M.R. Smith, Polyhedron 18 (1999)
2405;
(d) D. Neculai, H.W. Roesky, A.M. Neculai, J. Magull, H.-G.
5. Supplementary material
Schmidt, M. Noltemeyer, J. Organomet. Chem. 643ꢁ
/
644 (2002)
47;
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Center as supplemen-
tary publication nos. CCDC 196926-196930 Copies of
the data can be obtained free of charge on application to
the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(e) P.H.M. Budzelaar, R. de Gelder, A.W. Gal, Organometallics
17 (1998) 4121;
(f) W.-K. Kim, M.J. Fevola, L.M. Liable-Sands, A.L. Rheingold,
K.H. Theopold, Organometallics 17 (1998) 4541;
(g) D. Dress, J. Magull, Z. Anorg. Allg. Chem. 620 (1994)
814;
(fax:
ac.uk).
ꢂ44-1223-336033; e-mail: deposit@ccdc.cam.
/
(h) D. Dress, J. Magull, Z. Anorg. Allg. Chem. 621 (1995)
948.
[6] P.H.M. Budzelaar, A.B. van Oort, A.G. Orpen, Eur. J. Inorg.
Chem. (1998) 1485.
[7] M. Stender, R.J. Wright, B.E. Eichler, J. Prust, M.M. Olmstead,
H.W. Roesky, P.P. Power, J. Chem. Soc., Dalton Trans. (2001)
3465.
Acknowledgements
Support of the Deutsche Forschungsgemeinschaft and
the Gottinger Akademie der Wissenschaften is highly
¨
[8] F.A. Cotton, C.A. Murillo, M.A. Petrukhina, J. Organomet.
Chem. 573 (1999) 78.
acknowledged. N.S.H. thanks the Humboldt foundation
for a research award.
[9] M. Horacek, V. Kupfer, U. Thewalt, M. Polasek, K. Mach, J.
Organomet. Chem. 579 (1999) 126.
[10] R. Jungst, D. Sekutowski, J. Davis, M. Luly, G. Stucky, Inorg.
Chem. 16 (1977) 1645.
[11] J.M. McInnes, A.J. Blake, P. Mountford, J. Chem. Soc., Dalton
Trans. (1998) 3623.
References
[12] D.P. Steinhuebel, S.J. Lippard, Inorg. Chem. 38 (1999) 6225.
[13] J.D. Gardner, D.A. Robson, L.H. Rees, P. Mountford, Inorg.
Chem. 40 (2001) 820.
[1] (a) M.F. Lappert, D.S. Liu, J. Organomet. Chem. 500 (1995) 203;
(b) J. Feldman, S.J. McLain, A. Parthasarathy, W.J. Marshall,

G.B. Nikiforov et al. / Polyhedron 22 (2003) 2669ꢁ
/2681
2681
[14] A.J. Nielson, M.W. Glenny, C.E.F. Rickard, J. Chem. Soc.,
Dalton Trans. (2001) 232.
[15] A.J. Blake, P.E. Collier, L.H. Gade, P. Mountford, J. Lloyd, S.M.
[27] A. Herzog, F.-Q. Liu, H.W. Roesky, A. Demsar, K. Keller, M.
Noltemeyer, F. Pauer, Organometallics 13 (1994) 1251.
[28] A. Bodner, P. Jeske, T. Weyhermuller, K. Wieghardt, E. Dubler,
¨
Pugh, M. Schubart, M.E.G. Skinner, D.J.M. Trosch, Inorg.
¨
Chem. 40 (2001) 870.
H. Schmalle, B. Nuber, Inorg. Chem. 31 (1992) 3737.
[29] J.R. Hagadorn, J. Arnold, Organometallics 17 (1998) 1355.
[30] J.E. Hill, P.E. Fanwick, I.P. Rothwell, Inorg. Chem. 28 (1989)
3602.
[16] P.J. Wilson, A.J. Blake, P. Mountford, M. Schroeder, J.
Organomet. Chem. 600 (2000) 71.
[17] P.B. Hitchcock, M.F. Lappert, D.-S. Liu, J. Chem. Soc., Chem.
Commun. (1994) 2637.
[31] (a) F.-Q. Liu, D. Stalke, H.W. Roesky, Angew. Chem. 107 (1995)
2004;
[18] P.B. Hitchcock, M.F. Lappert, D.-S. Liu, J. Organomet. Chem.
488 (1995) 241.
[19] N.C. Mosch-Zanetti, R. Kratzner, C. Lehmann, T.R. Schneider,
(b) F.-Q. Liu, D. Stalke, H.W. Roesky, Angew. Chem., Int. Ed.
34 (1995) 1872.
[32] (a) F.-Q. Liu, A. Kuhn, R. Herbst-Irmer, D. Stalke, H.W.
Roesky, Angew. Chem. 106 (1994) 577;
¨
¨
I. Uso´n, Eur. J. Inorg. Chem. (2000) 13.
[20] (a) V.V. Tkachev, L.O. Atovmyan, Zh. Struct. Khim. 13 (1972)
(b) F.-Q. Liu, A. Kuhn, R. Herbst-Irmer, D. Stalke, H.W.
Roesky, Angew. Chem., Int. Ed. 33 (1994) 555.
[33] (a) P. Yu, P. Muller, H.W. Roesky, M. Noltemeyer, A. Demsar, I.
¨
287;
(b) V.V. Tkachev, L.O. Atovmyan, Ceramic Age 77 (1972)
25844f.
[21] T.C. McKenzie, R.D. Sanner, J.E. Bercaw, J. Organomet. Chem.
Uso´n, Angew. Chem. 111 (1999) 3518;
(b) P. Yu, P. Muller, H.W. Roesky, M. Noltemeyer, A. Demsar, I.
¨
102 (1975) 457.
[22] D. Fenske, E. Hartmann, K. Dehnicke, Z. Naturforsch. Teil. B 43
(1988) 1611.
Uso´n, Angew. Chem., Int. Ed. 38 (1999) 3319.
[34] E.G. Perevalova, I.F. Urazowski, D.A. Lemenovskii, Yu.L.
Slovokhotov, J. Organomet. Chem. 289 (1985) 319.
[35] L.B. Kool, D.M. Rausch, H.G. Alt, M. Herberhold, U. Thewalt,
B. Honold, J. Organomet. Chem. 310 (1986) 27.
[23] R. Buheitel, W. Milius, W. Schnick, Z. Naturforsch. Teil. B 51
(1996) 1141.
[24] F.-Q. Liu, A. Kunzel, A. Herzog, H.W. Roesky, M. Noltemeyer,
¨
[36] J. Darkwa, J.R. Lockemeyer, P.D.W. Boyd, T.B. Rauchfuss, A.L.
Rheingold, J. Am. Chem. Soc. 110 (1988) 141.
R. Fleischer, D. Stalke, Polyhedron 16 (1997) 61.
[25] (a) F.-Q. Liu, H. Gornitzka, D. Stalke, H.W. Roesky, Angew.
Chem. 105 (1993) 447;
[37] S.G. McGeachin, Can. J. Chem. 46 (1968) 1903.
[38] N. Kuhn, H. Lanfermann, P. Schmitz, Liebigs Ann. Chem. (1987)
727.
(b) F.-Q. Liu, H. Gornitzka, D. Stalke, H.W. Roesky, Angew.
Chem., Int. Ed. 32 (1993) 442.
[39] E. Krause, Ber. Dtsch. Chem. Ges. 51 (1918) 1447.
[40] G.M. Sheldrick, SHELXL: Program for Crystal Structure Refine-
ment, University of Gottingen, Gottingen, Germany, 1997.
[26] E.G. Il’in, G.B. Nikiforov, G.G. Aleksandrov, H.W. Roesky,
Yu.A. Buslaev, Dokl. Chem. 376 (2001) 58.
¨
¨