Structural control of (arylimido)vanadium(V) compounds through π conjugation

Article abstract of DOI:10.1002/ejic.200701252

(Arylimido)triethanolaminatovanadium(V) compounds, [V(p-RC ₆H₄N)(TEA)] (R = NMe₂, OMe, Me, H, Cl, Br, CN), were synthesised by ligand exchange reaction of the corresponding (arylimido)triisopropoxidovanadium(V) complexes,

Full text of DOI:10.1002/ejic.200701252

FULL PAPER
DOI: 10.1002/ejic.200701252
Structural Control of (Arylimido)vanadium(V) Compounds through
π Conjugation
Toshiyuki Moriuchi,*[a] Tomohiko Beppu,[a] Kenta Ishino,[a] Masafumi Nishina,[a] and
Toshikazu Hirao*[a]
Keywords: Vanadium / Multiple bonds / Coordination modes / N,O ligands / Structure elucidation
(Arylimido)triethanolaminatovanadium(V) compounds, [V(p-
RC6H4N)(TEA)] (R = NMe2, OMe, Me, H, Cl, Br, CN), were
synthesised by ligand exchange reaction of the correspond-
ing (arylimido)triisopropoxidovanadium(V) complexes, [V-
(OiPr)3(p-RC6H4N)], which were prepared by the reaction of
VO(OiPr)3 with various p-substituted aryl isocyanates with-
out solvent. Structural characterisation of the (arylimido)tri-
ethanolaminatovanadium(V) products was carried out by
single-crystal X-ray diffraction in order to elucidate the sub-
stituent effect on the imido structures, in which the imido
structures were found to be controlled through π conjugation
by the para substituents of the aryl moieties.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
line state.[3e,3r] To prevent the dimerisation, triethanolamine
was used as a basal ligand.[7] The reaction of VO(OiPr)3
with various p-substituted aryl isocyanates without solvent
at 140 °C afforded the corresponding (arylimido)triiso-
propoxidovanadium(V) complexes, [V(OiPr)3(p-RC6H4N)].
The ligand exchange reaction with triethanolamine in
CH2Cl2 at room temperature led to the desired (arylimido)-
triethanolaminatovanadium(V) complexes, [V(p-RC6H4N)-
(TEA)] (Scheme 1; 1: R = NMe2, 2: R = OMe, 3: R = Me,
4: R = H, 5: R = Cl, 6: R = Br, 7: R = CN).
Introduction
The imido ligand coordinates through a metal–nitrogen
multiple bond[1] in which the imido ligand can serve as an
ancillary or supporting ligand. Imido ligands are known to
be particularly suitable for stabilisation of complexes con-
taining metals in high oxidation states through extensive
ligand-to-metal π donation.[2] (Imido)vanadium(V) com-
plexes have attracted much attention[3] because of their po-
tential applications as a catalysts for olefin polymerisa-
tion,[4] C–H activation[5] and other related processes.[6] In-
troduction of a substituent onto the imido ligands can be
expected to influence the steric and electronic properties of
a vanadium centre. In such a sense, design of the imido
ligands can be considered to be one of key factors in the
development of efficient catalysts. The substituent effect of
the imido ligands has been reported based only on spectro-
scopic and theoretical evidence.[3e] The systematic corre-
lation between the properties and the imido structures has
yet to be investigated. We herein report the structural char-
acterisation of (arylimido)triethanolaminatovanadium(V)
compounds for the purposes of elucidating the substituent
effect of the aryl moieties on the imido structures.
Scheme 1. Preparation of the (arylimido)triethanolaminatovanadi-
um(V) complexes 1–7.
51V NMR spectroscopic measurements were performed
in order to clarify the substituent effect on the electronic
environment of the vanadium species. The 51V chemical
shift of the unsubstituted (phenylimido)vanadium(V) com-
plex 4 was detected at –327 ppm. In the 51V NMR spectra
of the (arylimido)triethanolaminatovanadium(V) species,
51V chemical shifts were observed at the lower field with
an increase in the electron-donating capability of the para
substituent (1: –224 ppm, 2: –292 ppm, 3: –314 ppm). In
Results and Discussion
(Arylimido)triisopropoxidovanadium(V) compounds are
considered to dimerise through oxo-bridging in the crystal-
[a] Department of Applied Chemistry, Graduate School of Engi-
neering, Osaka University,
Yamada-oka, Suita, Osaka 565-0871, Japan
Fax: +81-6-6879-7415
E-mail: moriuchi@chem.eng.osaka-u.ac.jp
hirao@chem.eng.osaka-u.ac.jp
Eur. J. Inorg. Chem. 2008, 1969–1973
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1969

T. Moriuchi, T. Beppu, K. Ishino, M. Nishina, T. Hirao
FULL PAPER
contrast, the electron-withdrawing substituent, in which the crystal X-ray diffraction in order to elucidate the substitu-
nitrogen atom of the imido bond becomes more electroneg- ent effect on the imido structures (Figure 1). The important
ative and increases the 51V nuclear shielding, causes the bond lengths and angles are listed in Table 1.
higher field shift (5: –328 ppm, 6: –328 ppm, 7: –340 ppm).
The non-substituted (phenylimido)vanadium(V) complex
These results are consistent with those of the (arylimido)- 4 revealed an imido structure with a V(1)–N(1) distance of
trichloridovanadium(V) compounds reported by Maatta 1.686(2) Å and a V(1)–N(1)–C(1) angle of 166.7(2)° in
and co-workers.[3e]
which a monomeric structure with a pseudo-trigonal bipy-
Structural characterisation of the (arylimido)triethanol- ramidal geometry at the metal centre was observed and this
aminatovanadium(V) complexes was carried out by single- is depicted in Figure 1.
Figure 1. Molecular structures and schematic representations of 1–7.
Table 1. Selected bond lengths [Å] and angles [°] for 1–7.
1[a]
2
3
4
5
6
7[a]
Bond lengths
V1–N1
V1–N2
V1–O1
V1–O2
V1–O3
C1–N1
1.677(3)
2.223(2)
1.838(2)
1.824(3)
1.835(3)
1.379(4)
1.680(4)
2.223(3)
1.833(2)
1.828(2)
1.834(2)
1.368(5)
1.688(2)
2.231(2)
1.830(1)
1.828(1)
1.829(1)
1.367(2)
1.686(2)
2.223(2)
1.829(2)
1.830(2)
1.821(2)
1.377(3)
1.686(2)
2.221(2)
1.834(2)
1.815(2)
1.831(2)
1.370(3)
1.689(2)
2.221(2)
1.826(1)
1.827(1)
1.812(2)
1.368(3)
1.697(4)
2.221(4)
1.826(3)
1.817(4)
1.833(3)
1.370(6)
1.671(3)
2.205(3)
1.811(3)
1.824(3)
1.809(3)
1.373(5)
1.676(3)
2.212(3)
1.819(3)
1.816(3)
1.806(3)
1.375(5)
Bond angles
C1–N1–V1
N1–V1–N2
N1–V1–O1
N1–V1–O2
N1–V1–O3
O1–V1–O2
O1–V1–O3
O2–V1–N2
O2–V1–O3
O3–V1–N2
O3–V1–N2
179.0(3)
179.1(1)
98.7(1)
99.6(1)
99.5(1)
116.1(1)
118.1(1)
80.6(1)
118.2(1)
81.16(10)
80.5(1)
178.8(2)
179.2(1)
99.1(1)
99.7(2)
99.1(1)
118.0(1)
117.6(1)
80.5(1)
116.8(1)
81.1(1)
80.5(1)
172.8(2)
178.20(8)
97.79(8)
100.14(7)
100.18(7)
118.04(6)
117.09(6)
80.42(6)
117.08(6)
80.61(6)
80.86(5)
162.6(2)
175.46(8)
100.43(8)
95.60(8)
102.10(9)
117.53(8)
116.52(8)
80.48(7)
118.16(8)
80.10(8)
81.32(8)
166.7(2)
177.48(7)
97.04(8)
100.46(9)
100.50(8)
118.32(8)
117.14(7)
80.44(6)
116.80(8)
80.66(7)
80.91(6)
162.9(1)
175.52(7)
99.86(7)
95.84(7)
102.28(8)
118.78(6)
115.73(7)
80.69(6)
117.81(7)
80.07(6)
81.36(7)
164.4(4)
175.2(2)
100.0(2)
102.7(2)
95.5(2)
115.6(2)
118.4(1)
80.7(2)
170.5(3)
178.4(2)
100.0(1)
100.4(1)
97.8(2)
118.7(1)
118.4(1)
80.6(1)
170.7(3)
178.4(2)
100.6(1)
98.0(2)
100.1(1)
115.2(1)
118.5(1)
80.3(1)
118.2(2)
81.1(2)
80.1(2)
115.1(1)
80.6(1)
80.6(1)
118.2(1)
80.4(1)
80.6(1)
[a] Two independent molecules exist in the asymmetric unit.
1970
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Eur. J. Inorg. Chem. 2008, 1969–1973

Structural Control of (Arylimido)vanadium(V) Compounds
The vanadium atom is pulled out of the plane formed by ever, a bent imido bond was observed in the case of the
triethanolaminato oxygen atoms in the direction of the (arylimido)vanadium(V) complex 3 bearing the methyl
imido nitrogen. The three equatorial vanadium–oxygen group [Figure 1, V(1)–N(1)–C(1) 162.6(2)°; V(1)–N(1)
bond lengths are statistically identical.
1.686(2) Å]. From these results, the structures of the imido
In the case of the (arylimido)vanadium(V) complex 2 bonds are likely to depend on π conjugation contributions
with the electron-donating methoxy group, linearity of the rather than inductive effects. This contribution is supported
imido angle has increased [V(1)–N(1)–C(1), 172.8(2)°] al- by the following findings. The crystal structure of the (aryl-
though the V(1)–N(1) distance of 1.688(2) Å is equal to that imido)vanadium(V) complex 7 with the cyano group, in
observed in 4 (Figure 1). Furthermore, the imido angle is which two independent molecules exist in the asymmetric
greater in the (arylimido)vanadium(V) complex 1 bearing unit, exhibits almost linear V(1)–N(1)–C(1) angles of
the dimethylamino group. V(1)–N(1)–C(1) angles of 170.5(3) and 170.7(3)° with V(1)–N(1) distances of 1.671(3)
179.0(3) and 178.8(2)° and V(1)–N(1) distances of 1.677(3) and 1.676(3) Å, probably due to the π-conjugation contri-
and 1.680(4) Å were observed in the crystal structure (Fig- bution as shown in Figure 1. On the contrary, the introduc-
ure 1). Since 1 crystallises in the space group P21/a with Z tion of the halo group led to a more bent imido bond [5:
= 8, two independent molecules exist in the asymmetric V(1)–N(1)–C(1) 162.9(1)°; V(1)–N(1) 1.689(2) Å; 6: V(1)–
unit. It is noteworthy that the triethanolamine moieties of N(1)–C(1) 164.4(4)°; V(1)–N(1) 1.697(4) Å] than in 4 (Fig-
these independent molecules adopt a mirror image wind- ure 1).
mill-like conformation (Figure 2). In the crystal, these
In the (arylimido)vanadium(V) complexes described in
molecules pack in a face-to-face manner with an in- this paper, the structures of the triethanolamine moieties
terplanar distance of ca. 3.6 Å between the aryl moieties are almost the same and any notable differences were not
which form a π stacked dimer as depicted in Figure 3. How- observed in the V(1)–N(1) and C(1)–N(1) distances. It
should be noted that the para substituent of the aryl moiety
was also found to affect the twist angle β defined as the
angle between the least-squares plane of the benzene ring
and the C(ipso)–imido bond (Figure 4 and Table 2) which
is considered to correlate to the properties of the imido
bond. An almost perpendicular twist angle β was observed
in the case of the complexes with the π-conjugating elec-
tron-donating substituent [43.11(9)° and 101.82(9)° for 1;
95.92(5)° for 2]. However, the benzene rings of other (aryl-
imido)vanadium(V) complexes are nearly parallel to the
Figure 2. Two independent molecules, which are conformational
least-squares plane of the corresponding C(ipso)–imido
enantiomers, exist in the asymmetric unit of 1. Projection down
bonds [8.69(6)° for 3; 8.35(6)° for 4; 9.27(5)° for 5; 11.2(1)°
from the imido nitrogen of the conformational enantiomers of 1
for 6; 9.2(1)° and 10.4(1)° for 7]. The linear imido angle and
the almost perpendicular twist angle β of the (arylimido)-
vanadium(V) complexes with the π-conjugating electron-
donating substituent might be due to greater participation
of sp hybrid character in the nitrogen of the imido bond
(Figure 5). The lone pair of electrons is likely to be localised
in a nitrogen p orbital, the latter being likely to interact
with the metal π acceptor orbitals and aryl π orbitals. In
(only the molecular structure of the triethanolamine moiety is de-
picted); the triethanolamine moiety adopts a windmill-like confor-
mation and the enantiomorphs are related by the mirror plane.
Figure 4. The twist angle β defined as the angle between the least-
squares plane of the benzene ring and the C(ipso)–imido bond.
Figure 3. The π-stacked dimer in the crystal packing of 1.
Table 2. The twist angle β defined as the angle between the least-squares plane of the benzene ring and the C(ipso)–imido bond of 1–7.
1[a]
2
3
4
5
6
7[a]
β
43.11(9), 101.82(9)
95.92(5)
8.69(6)
8.35(6)
9.27(5)
11.2(1)
9.2(1), 10.4(1)
[a] Two independent molecules exist in the asymmetric unit.
Eur. J. Inorg. Chem. 2008, 1969–1973
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1971

T. Moriuchi, T. Beppu, K. Ishino, M. Nishina, T. Hirao
FULL PAPER
contrast, the larger contribution of sp2 hybrid character in
the nitrogen of the imido bond can be suggested because of
the bent imido bond and the nearly parallel twist angle β
in the case of the (arylimido)vanadium(V) complexes bear-
ing no π-conjugating electron-donating substituent, wherein
the filled imido π orbital seems to interact with the aryl π
orbitals.
by the reaction of VO(OiPr)3 with the corresponding p-substituted
aryl isocyanate. 1H NMR spectra were recorded on JEOL JNM-
ECP 400 (400 MHz) and Varian MERCURY 300 (300 MHz) spec-
trometers. The chemical shifts were referenced to the residual reso-
nances of the deuterated solvents. 51V NMR spectra were obtained
with a JEOL JNM-ECP 400 (105 MHz) spectrometer with VOCl3
as an external standard.
General Procedure for the Preparation of (Arylimido)triethanolamin-
atovanadium(V) Complexes: To a stirred dichloromethane (5 mL)
solution of the (arylimido)triisopropoxidovanadium(V), [V(OiPr)3-
(p-RC6H4N)] (0.2 mmol) was added a dichloromethane (5 mL)
solution of triethanolamine (45 mg, 0.3 mmol) under nitrogen at
room temperature. The mixture was stirred at room temperature
for 3 h. The solvent was removed in vacuo and the resultant residue
was washed with acetonitrile. The desired (arylimido)triethanolam-
inatovanadium(V) complex was isolated by recrystallisation from
dichloromethane/hexane.
1
1: NMR yield 85%. H NMR (400 MHz, CD2Cl2): δ = 7.11 (d, J
= 9.1 Hz, 2 H), 6.49 (d, J = 9.1 Hz, 2 H), 4.62 (t, J = 5.6 Hz, 6 H),
3.02 (t, J = 5.6 Hz, 6 H), 3.00 (s, 6 H) ppm. 51V NMR (105 MHz,
CD2Cl2): δ = –224 ppm.
1
2: NMR yield 95%. H NMR (400 MHz, CD2Cl2): δ = 7.17 (d, J
Figure 5. Proposed valence bond structures for a vanadium bound
imido ligand.
= 9.1 Hz, 2 H), 6.74 (d, J = 9.1 Hz, 2 H), 4.64 (t, J = 5.6 Hz, 6 H),
3.78 (s, 3 H), 3.06 (t, J = 5.6 Hz, 6 H) ppm. 51V NMR (105 MHz,
CD2Cl2): δ = –292 ppm.
3: NMR yield quantitatively. 1H NMR (300 MHz, CD2Cl2): δ =
7.07 (d, J = 8.7 Hz, 2 H), 7.05 (d, J = 8.7 Hz, 2 H), 4.65 (t, J =
5.6 Hz, 6 H), 3.07 (t, J = 5.6 Hz, 6 H), 2.35 (s, 3 H) ppm. 51V NMR
(105 MHz, CD2Cl2): δ = –314 ppm.
Conclusions
A variety of (arylimido)triethanolaminatovanadium(V)
complexes, [V(p-RC6H4N)(TEA)], were synthesised by
the ligand exchange reaction of the corresponding (aryl-
imido)triisopropoxidovanadium(V) species, [V(OiPr)3(p-
RC6H4N)], which were prepared by the reaction of
VO(OiPr)3 with various p-substituted aryl isocyanates with-
out solvent. Structural characterisation of the (arylimido)-
triethanolaminatovanadium(V) compounds was carried out
by single-crystal X-ray diffraction in order to elucidate the
substituent effect on the imido structures. The para substit-
1
4: NMR yield 98%. H NMR (400 MHz, CD2Cl2): δ = 7.25 (dd,
J = 8.4, 7.3 Hz, 2 H), 7.19 (d, J = 8.4 Hz, 2 H), 7.02 (t, J = 7.3 Hz,
1 H), 4.67 (t, J = 5.6 Hz, 6 H), 3.10 (t, J = 5.6 Hz, 6 H), 3.00 (s, 6
H) ppm. 51V NMR (105 MHz, CD2Cl2): δ = –327 ppm.
1
5: NMR yield 71%. H NMR (300 MHz, CD2Cl2): δ = 7.22 (d, J
= 9.0 Hz, 2 H), 7.14 (d, J = 9.0 Hz, 2 H), 4.67 (t, J = 5.7 Hz, 6 H),
3.11 (t, J = 5.7 Hz, 6 H) ppm. 51V NMR (105 MHz, CD2Cl2): δ =
–328 ppm.
1
uent of the aryl moiety was found to affect the properties 6: NMR yield 73%. H NMR (300 MHz, CD2Cl2): δ = 7.37 (d, J
= 9.0 Hz, 2 H), 7.08 (d, J = 9.0 Hz, 2 H), 4.67 (t, J = 5.7 Hz, 6 H),
3.11 (t, J = 5.7 Hz, 6 H) ppm. 51V NMR (105 MHz, CD2Cl2): δ =
–328 ppm.
and structures of the (arylimido)vanadium(V) compounds
through π conjugation which can be envisioned as con-
trolling the electronic properties of the vanadium centres.
Regulation of redox properties of the vanadium centres is
considered to be one of key factors in the development of
1
7: NMR yield 72%. H NMR (300 MHz, CD2Cl2): δ = 7.54 (d, J
= 9.0 Hz, 2 H), 7.25 (d, J = 9.0 Hz, 2 H), 4.70 (t, J = 5.7 Hz, 6 H),
an efficient vanadium catalytic system.[8] Further character- 3.15 (t, J = 5.7 Hz, 6 H) ppm. 51V NMR (105 MHz, CD2Cl2): δ =
–340 ppm.
isation of the imido structures and the application of the
(arylimido)vanadium(V) complexes for catalysis based on
the redox control of the vanadium centres are now in pro-
gress.
X-ray Structure Analysis: All measurements for 1–7 were made on
a Rigaku RAXIS-RAPID Imaging Plate diffractometer with
graphite-monochromated Mo-Kα radiation. The structures of 1–7
were solved by direct methods and expanded using Fourier tech-
niques. The non-hydrogen atoms were refined anisotropically. The
H atoms were placed in idealised positions and allowed to ride with
the C atoms to which each was bonded. Crystallographic details
are summarised in Table 3.
Experimental Section
General: All manipulations were carried out under nitrogen in a
vacuum atmospheres drybox or using standard Schlenk techniques.
All reagents and solvents were purchased from commercial sources
and were further purified by standard methods, if necessary. Sol-
vents employed were dried by heating to reflux in the presence of
appropriate drying reagents, distilled under nitrogen and stored in
the drybox. (Arylimido)triisopropoxidovanadium(V) was prepared
CCDC-656911 (for 1), -656912 (for 2), -656913 (for 3), -656914 (for
4), -656915 (for 5), -656916 (for 6) and -656917 (for 7) contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
1972
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1969–1973

Structural Control of (Arylimido)vanadium(V) Compounds
Table 3. Crystallographic data for 1–7.
1
2
3
4
5
6
7
Empirical formula
Formula weight
C
331.29
14H22N3O3V
C13H19N2O4V
318.25
C13H19N2O3V
302.25
C12H17N2O3V
288.22
C12H16ClN2O3V C12H16BrN2O3V C13H16N3O3V
322.66
367.12
313.23
Crystal system
Space group
a [Å]
b [Å]
c [Å]
monoclinic
monoclinic
orthorhombic
orthorhombic
Pbca (No. 61)
10.2721(7)
13.182(1)
19.0852(7)
–
–
–
2584.3(3)
8
1.481
7.69
4
orthorhombic
Pbca (No. 61)
11.1021(4)
13.2196(5)
18.8345(4)
–
–
–
2764.2(2)
8
1.551
9.15
23
orthorhombic
Pbca (No. 61)
11.3257(8)
13.2396(6)
18.871(1)
–
–
–
2829.6(3)
8
1.723
35.38
2
triclinic
P1 (No. 2)
¯
P21/a (No. 14) P21/n (No. 14) Pbca (No. 61)
20.1234(4)
6.5842(1)
25.2351(5)
–
112.5650(5)
–
3087.6(1)
8
1.425
7.8878(3)
9.6141(3)
18.7779(7)
–
94.103(2)
–
1420.35(8)
4
1.488
10.8886(4)
13.2292(4)
19.2607(6)
–
–
–
2774.4(2)
8
1.447
7.20
4
6.5936(1)
10.2657(2)
20.3733(2)
89.907
96.997(1)
90.072(1)
1368.77(3)
4
α [°]
β [°]
γ [°]
V [Å3]
Z
Dcalcd. [g cm–3
]
1.520
7.35
23
µ(Mo-Kα) [cm–1
T [°C]
]
6.55
23
7.12
23
λ(Mo-Kα) [Å]
0.71069
0.052
0.163
0.71069
0.044
0.134
0.71069
0.049
0.150
0.71069
0.046
0.175
0.71069
0.047
0.138
0.71069
0.044
0.151
0.71069
0.046
0.142
R1[a]
wR2[b]
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|. [b] wR2 = [Σw(Fo – Fc ) /Σw(Fo2)2]1/2
.
2
2 2
Organometallics 2005, 24, 3621–3623; v) S. Dürr, B. Bechlars,
U. Radius, Inorg. Chim. Acta 2006, 359, 4215–4226; w) C.
Lorber, R. Choukroun, L. Vendier, Inorg. Chem. 2007, 46,
3192–3202.
Acknowledgments
Thanks are due to the Analytical Centre, Graduate School of Engi-
neering, Osaka University, for the use of the NMR instruments.
[4]
a) S. Scheuer, J. Fischer, J. Kress, Organometallics 1995, 14,
2627–2629; b) M. C. W. Chan, J. M. Cole, V. C. Gibson,
J. A. K. Howard, Chem. Commun. 1997, 2345–2346; c)
M. C. W. Chan, K. C. Chew, C. I. Dalby, V. C. Gibson, A.
Kohlmann, I. R. Little, W. Reed, Chem. Commun. 1998, 1673–
1674; d) M. P. Coles, C. I. Dalby, V. C. Gibson, I. R. Little,
E. L. Marshall, M. H. Ribeiro da Costa, S. Mastroianni, J. Or-
ganomet. Chem. 1999, 591, 78–87; e) H. Hagen, C. Bezemer, J.
Boersma, H. Kooijman, M. Lutz, A. L. Spek, G. van Koten,
Inorg. Chem. 2000, 39, 3970–3977; f) K. Nomura, A. Sagara,
Y. Imanishi, Chem. Lett. 2001, 36–37; g) J. Yamada, M. Fujiki,
K. Nomura, Organometallics 2005, 24, 2248–2250; h) Y. Sato,
Y. Nakayama, H. Yasuda, J. Appl. Polym. Sci. 2005, 97, 1008–
1015; i) H. R. Bigmore, M. A. Zuideveld, R. M. Kowalczyk,
A. R. Cowley, M. Kranenburg, E. J. L. Mclnnes, P. Mountford,
Inorg. Chem. 2006, 45, 6411–6423.
a) J. de With, A. D. Horton, A. G. Orpen, Organometallics
1990, 9, 2207–2209; b) J. de With, A. D. Horton, Angew. Chem.
Int. Ed. Engl. 1993, 32, 903–905; c) J. de With, A. D. Horton,
A. G. Orpen, Organometallics 1993, 12, 1493–1496; d) T. R.
Cundari, Organometallics 1994, 13, 2987–2994.
a) K. R. Birdwhistell, T. Boucher, M. Ensminger, S. Harris, M.
Johnson, S. Toporek, Organometallics 1993, 12, 1023–1025; b)
F. Tabellion, A. Nachbauer, S. Leininger, C. Peters, F. Preuss,
M. Regitz, Angew. Chem. Int. Ed. 1998, 37, 1233–1235; c) K. R.
Birdwhistell, J. Lanza, J. Pasos, J. Organomet. Chem. 1999, 584,
200–205; d) C. Peters, F. Tabellion, M. Schröder, U. Berg-
sträßer, F. Preuss, M. Regitz, Synthesis 2000, 417–428; e) F.
Montilla, A. Pastor, A. Galindo, J. Organomet. Chem. 2004,
689, 993–996; f) C. Lorber, R. Choukroun, L. Vendier, Organo-
metallics 2004, 23, 1845–1850; g) F. Montilla, D. del Río, A.
Pastor, A. Galindo, Organometallics 2006, 25, 4996–5002.
[1] T. R. Cundari, Chem. Rev. 2000, 100, 807–818.
[2] a) D. E. Wigley in Progress in Inorganic Chemistry, vol. 42 (Ed.:
K. D. Karlin), Wiley-Interscience, New York, 1994, pp. 239–
482; b) W. A. Nugent, J. M. Mayer, Metal-Ligand Multiple
Bonds, Wiley-Interscience, New York, 1998.
[3] a) F. Preuss, W. Towae, Z. Naturforsch. Teil B 1981, 36, 1130–
1135; b) F. Preuss, W. Towae, V. Kruppa, E. Fuchslocher, Z.
Naturforsch. Teil B 1984, 39, 1510–1517; c) E. A. Maatta, In-
org. Chem. 1984, 23, 2560–2561; d) F. Preuss, H. Becker, H.-J.
Häusler, Z. Naturforsch. Teil B 1987, 42, 881–888; e) D. D. De-
vore, J. D. Lichtenhan, F. Takusagawa, E. A. Maatta, J. Am.
Chem. Soc. 1987, 109, 7408–7416; f) F. Preuss, H. Becker, J.
Kaub, W. S. Sheldrick, Z. Naturforsch. Teil B 1988, 43, 1195–
1200; g) T. Carofiglio, C. Floriani, A. Chiesi-Villa, C. Guastini,
Inorg. Chem. 1989, 28, 4417–4419; h) J. de With, A. D. Horton,
A. G. Orpen, Organometallics 1990, 9, 2207–2209; i) W.-H.
Leung, A. A. Danopoulos, G. Wilkinson, B. Hussain-Bates,
M. B. Hursthouse, J. Chem. Soc., Dalton Trans. 1991, 2051–
2061; j) W. Plass, J. G. Verkade, Inorg. Chem. 1993, 32, 3762–
3765; k) G. A. Solan, P. G. Cozzi, C. Floriani, A. Chiesi-Villa,
C. Rizzoli, Organometallics 1994, 13, 2572–2574; l) J.-K. F. Bui-
jink, A. Meetsma, J. H. Teuben, H. Kooijman, A. L. Spek, J.
Organomet. Chem. 1995, 497, 161–170; m) P. L. Hill, G. P. A.
Yap, A. L. Rheingold, E. A. Maatta, J. Chem. Soc. Chem.
Commun. 1995, 737–738; n) M. G. Fickes, W. M. Davis, C. C.
Cummins, J. Am. Chem. Soc. 1995, 117, 6384–6385; o) V. J.
Murphy, H. Turner, Organometallics 1997, 16, 2495–2497; p)
P. T. Witte, A. Meetsma, B. Hessen, J. Am. Chem. Soc. 1997,
119, 10561–10562; q) D. E. Wheeler, J.-F. Wu, E. A. Maatta,
Polyhedron 1998, 17, 969–976; r) M. Lutz, H. Hagen, A. M. M.
Schreurs, A. L. Spek, G. van Koten, Acta Crystallogr. Sect. C
1999, 55, 1636–1639; s) F. Montilla, A. Pastor, A. Monge, E.
Gutiérrez-Puebla, A. Galindo, J. Chem. Soc., Dalton Trans.
1999, 2893–2896; t) M. Billen, G. Hornung, F. Preuss, Z. Nat-
urforsch. Teil B 2003, 58, 975–989; u) J. Yamada, K. Nomura,
[5]
[6]
[7] D. C. Crans, H. Chen, O. P. Anderson, M. M. Miller, J. Am.
Chem. Soc. 1993, 115, 6769–6776.
[8] T. Hirao, Chem. Rev. 1997, 97, 2707–2724.
Received: November 21, 2007
Published Online: February 27, 2008
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