Bimetallic complexes: IV.1 Synthesis, dynamic behavior and reactions of C5H4PPh2-bridged Zr(II)-Mo(0) complexes

Article abstract of DOI:10.1016/S0022-328X(97)00582-2

The synthesis and reactions of bimetallic Zr(II)-Mo(0) complexes with bridging C₅H₄PPh₂ ligands (henceforth abbreviated as Cp′) are described. Reaction of Cp₂′ZrCl₂ (1) with n-butyllithium in THF produces a metastable material tentatively formulated as Cp₂′Zr·2 LiCl·4 THF (2). Diphenyldisulfide instantaneously converts 2 into the Zr(IV) dithiolate Cp₂′Zr(SPh)₂ (3). When 2 is treated with [Mo(CO)₄(norbornadiene)], an unstable intermediate is formed which can be trapped in good yield with tert-butylisocyanide to give [Cp₂′Zr(CNt-Bu)₂Mo(CO)₄] (4). Treatment of [Cp₂′Zr(Cl)(Me)Mo(CO)₃L] (L=CO (5a), PMe₃ (5b)) with cyclohexenyllithium in the presence of PMe₃ gives the corresponding binuclear cyclohexyne complexes [Cp₂′Zr(PMe₃)(C₆H₈)Mo(CO) ₃L] (6a, b). These complexes are fluxional on the NMR timescale due to a flip motion of the cyclohexyne ligand between two equivalent positions (ΔG^≠=(40±8) kJ/mol). Protonation in THF converts 6a into the cyclohexenyl zirconium complex [Cp₂′Zr(THF)(C₆H₉)Mo(CO) ₄]BPh₄ (7). Alkenes such as styrene, 4-chlorostyrene or norbornadiene give the expected insertion products 8a-c which, due to their insufficient stability, could not be isolated. Stable insertion products were, however, obtained with ketones such as benzophenone (9a), 1,3-diphenylacetone (9b) and cyclohexanone (9c).

Full text of DOI:10.1016/S0022-328X(97)00582-2

Ž
.
Journal of Organometallic Chemistry 552 1998 83–89
Bimetallic complexes
IV. Synthesis, dynamic behavior and reactions of C5H4 PPh2-bridged
1
ž /
ž /
Zr II –Mo 0 complexes
)
Wolfdieter A. Schenk , Thomas Gutmann
Institut fur Anorganische Chemie der UniÕersitat Wurzburg, Am Hubland, Wurzburg D-97074, Germany
¨
¨
¨
¨
Received 12 June 1997
Abstract
X
Ž .
Ž .
Ž
.
The synthesis and reactions of bimetallic Zr II –Mo 0 complexes with bridging C5H4PPh2 ligands henceforth abbreviated as Cp
are described. Reaction of CpX2ZrCl2 1 with n-butyllithium in THF produces a metastable material tentatively formulated as Cp2ZrP2
X
Ž .
X
Ž .
Ž
.
Ž
.
Ž .
LiClP4 THF 2 . Diphenyldisulfide instantaneously converts 2 into the Zr IV dithiolate Cp2Zr SPh
3 . When 2 is treated with
2
w
Ž
. Ž
.x
4
Mo CO norbornadiene , an unstable intermediate is formed which can be trapped in good yield with tert-butylisocyanide to give
4
X
X
w
Ž
.
Ž
. x Ž .
w
Ž
.Ž
.
Ž
.
x Ž
w
Ž
.
Ž
.
..
Ž
Cp2Zr CNt-Bu 2Mo CO 4 . Treatment of Cp2Zr Cl Me Mo CO 3L L5CO 5a , PMe3 5b with cyclohexenyllithium in the
X
Ž
.Ž
.
x Ž
.
presence of PMe3 gives the corresponding binuclear cyclohexyne complexes Cp2Zr PMe3 C6H8 Mo CO 3L 6a, b . These complexes
/
Ž
Ž
.
are fluxional on the NMR timescale due to a flip motion of the cyclohexyne ligand between two equivalent positions DG s 40"8
X
.
w
Ž
.Ž
.
Ž
. x
Ž .
kJrmol . Protonation in THF converts 6a into the cyclohexenyl zirconium complex Cp2Zr THF C6H9 Mo CO BPh4 7 . Alkenes
4
such as styrene, 4-chlorostyrene or norbornadiene give the expected insertion products 8a–c which, due to their insufficient stability,
Ž
.
could not be isolated. Stable insertion products were, however, obtained with ketones such as benzophenone 9a , 1,3-diphenylacetone
Ž
.
Ž .
9b and cyclohexanone 9c . q 1998 Elsevier Science S.A.
Keywords: Molybdenum; Zirconium; Alkyne complexes; Insertion reactions
1. Introduction
variety of interesting and synthetically useful insertion
reactions with polar double bonds such as aldehydes,
w x
ketones, nitriles 8–10 , and even metal-bound carbon
In the previous publications of this series, we have
described several attempts to achieve the cooperative
activation of polar molecules in the coordination sphere
w
x
monoxide 11 . Therefore, we expected that analogous
Ž .
Ž .
binuclear Zr II –Mo 0 complexes would exhibit a simi-
larly rich chemistry.
Ž
.
Ž .
of C5H4 PPh2-bridged binuclear Zr IV –M 0 com-
Ž
.
w
x
plexes MsMo, W 1–3 . Although this turned out to
be more difficult than anticipated, we have finally been
able to demonstrate the coupling of two tungsten-bound
nitrile ligands and a zirconium-bound methyl group to
2. Results and discussion
w x
give a bridging 1,3-diiminato ligand 1 .
2.1. Mononuclear zirconium complexes
The chemistry of d2-zirconocene complexes is in
many respects quite different from their d0-congeners.
Negishi et al. have developed a synthetically very
useful route to reactive d2-zirconocene complexes:
Treatment of zirconocene dichloride with n-butyl-
lithium at low temperature produces an unstable inter-
mediate, presumably dibutyl zirconocene, which upon
warm up eliminates butane and butene. The highly
reactive ‘zirconocene equivalent’ thus formed, adds a
wide variety of unsaturated systems including dienes
Ž .
Apart from being a strong reducing agent, the Zr II
center has a pronounced tendency to bind soft Lewis
bases, especially unsaturated systems such as alkenes or
w
x
alkynes 4–10 . Many of these complexes undergo a
)
Corresponding author.
1
w
x
w x
and alkynes 9,10 .
For Part III, see Ref. 1 .
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

(
)
84
W.A. Schenk, T. GutmannrJournal of Organometallic Chemistry 552 1998 83–89
NMR, the THF can be quantitatively and reversibly
exchanged for dimethoxyethane or 1,2-diphenyldi-
methoxyethane. The new adducts, however, do not crys-
tallize well and could not be isolated in an analytically
pure state. Although we do not know the precise nature
of 2, it is reasonable to assume that it contains chloride
bridges between Zr and Li similar to the crystallograph-
w
Ž
. Ž
Cp2Ti m-
2
ically characterized complexes
.
Ž
.
x w x w
Ž
.
Ž
.
Ž
.3x
Cl Mg THF
12 , t-BuC5H4 3La m-Cl Li THF
4
2
X
w
x
w
Ž
.
Ž
.
x w
x
13 , and Cp2Yb m-Cl Na dme
14 .
2
2 Ž .
Evidence that 2 is a Zr II equivalent comes from the
following observations. Treatment of 2 with diphenyld-
w x
isulfide gives the known zirconocene dithiolate 3 1
Ž ..
Ž
Eq. 2 .
Ž .
1
Ž
.
Similar treatment of bis diphenylphosphino zircono-
Ž .
cene dichloride 1 in THF with n-butyllithium in the
presence of an excess of 2-butyne did, in our hands, not
produce the expected zirconacyclopentadiene complex.
Ž .
Ž
Instead, a dark brown material 2 was obtained Eq.
Ž .
2
Ž ..
1
which could be recrystallized from
benzenerhexane. Elemental analyses and NMR spectra
indicated a composition CpX2 ZrP2 LiClP4 THF. Identi-
cal material was obtained without the addition of 2-
butyne or in the presence of PMe3 or t-BuNC, two
ligands which would be expected to give isolable zir-
Ž
.
With tetracarbonyl norbornadiene molybdenum an
instantaneous reaction as monitored by 1H and 31P
Ž
.
NMR ensues followed by slow decomposition. How-
ever, when a small amount of t-BuNC is added to the
reaction mixture right after the molybdenum complex
has dissolved, then the binuclear isocyanide complex 4
conocene complexes 4 . The 31 P NMR spectrum of 2
w x
exhibits a slightly broadened singlet at y19.0 ppm
which becomes sharp at 08C. As monitored by 1H
can be isolated in good yield Eq. 3 .
Ž
Ž ..
Table 1
X
a
w
Ž
.
Ž
.
x (
)
NMR spectroscopic data of binuclear complexes Cp2 Zr XY Mo CO 3L 4–9
1
31
Ž
.
Ž
.
No.
H NMR C6 D6
P NMR C6 D6
CpX
X, Y
0.86
4
5.82, 6.28
25.1
6a
6b
7
8a
8b
8c
9a
9b
9c
5.06, 5.23, 5.85, 6.35
5.20–6.10e,f
5.97, 6.47, 6.79
0.59b, 1.50c, 1.67c, 2.19c, 2.83c
0.62g, 1.80c, 1.93c, 2.34c, 3.10c
1.51i, 1.90i, 5.78i, 1.41k, 3.52k
y0.5, 27.6d, 28.6d
y0.4, 25.0h, 29.3h, y27.2h
31.5
30.6, 30.8l
30.9, 31.2l
30.1, 30.6l
27.8
5.53, 5.92, 6.56, 6.86
5.65, 5.91, 6.42, 6.44
5.53, 5.70, 6.45, 6.69
1.45c, 1.52c, 1.92c, 2.00c
1.67c, 1.80c, 1.90c, 2.12c,m
1.00–2.10n
29.6
28.2
aAryl signals in the 6.5–8.0 ppm region are uncharacteristic and have been omitted. For further data, see Section 4.
2
bd, J P–H s6 Hz, Zr–PMe3.
Ž
.
c m, C6 H8.
dAt 203 K, AB-system, J P–P s28 Hz.
2
Ž
.
em, Not resolved.
f
2
Ž
Ž
Ž
.
.
.
0.69 d, J P–H s7 Hz, Mo–PMe3 .
2
gd, J P–H s6 Hz, Zr–PMe3.
hAt 203 K, t, J P–P s27 Hz.
2
Ž
.
i
Ž
.
.
m C6 H9
k
Ž
.
m THF .
lAB-system, J P–P s28 Hz.
2
Ž
.
m
2
Ž
Ž
.
.
2.68, 3.11 AB-system, J H–H s16 Hz, CH2 Ph .
n m, not resolved, CH2.

(
)
W.A. Schenk, T. GutmannrJournal of Organometallic Chemistry 552 1998 83–89
85
aliphatic hydrocarbons. Its infrared spectrum exhibits
w
Ž
.
x
the typical pattern of a cis- Mo CO L2 complex and,
4
Ž
.
in addition, two strong n CN vibrations of the iso-
1
cyanide ligands. The H NMR spectrum consists of a
sharp singlet at 0.86 ppm for the t-butyl groups and two
multiplets for the CpX protons indicating that the
molecule has mirror symmetry. The phosphorus reso-
nance occurs at 25.1 ppm, the typical region for a CpX
w
x
ligand bridging a Zr and a Mo atom 1–3 .
2.2. Binuclear zirconium–molybdenum complexes
Ž
.
The metathesis of methyl chloro zirconocene with
alkenyllithium reagents is a proven route to zirconocene
Ž .
3
w
x
w x
complexes of alkynes 8,15 , including cyclohexyne 16 .
w x
Analogously, the binuclear complexes 5a, b 1 , upon
4 is a yellow, air-stable crystalline compound which
is soluble in the common organic solvents except
treatment with cyclohexenyllithium and trimethylphos-
Ž Ž ..
phine give the cyclohexyne complexes 6a, b Eq. 4 .
Ž .
4
6a, b were isolated as air-sensitive brownish-yellow
microcrystalline powders. Their infrared spectra exhibit
nonequivalent upon cooling. Based on the known struc-
ture of the mononuclear analog Cp2 Zr PMe3 cyclohe-
Ž .Ž
Ž
.
w
Ž
.
4 x
Ž
.
. w x
the expected n CO pattern of the cis- Mo CO
6a
6b unit, respectively. At room
temperature, the H and 31 P NMR spectra are broad-
ened indicating that the molecules are fluxional. The 31
xyne 16 , this dynamic process is most likely de-
scribed as a flip of the alkyne moiety between two
equivalent positions as outlined in Scheme 1. That this
motion is much slower in the binuclear complexes 6a, b
than in analogous mononuclear compounds is certainly
due to the rigidity brought into the system by tying the
two CpX ligands to a second metal center.
w
Ž
.
3x
Ž
.
and fac- Mo CO
1
P
NMR spectrum of 6a at 203 K consists of an AB-sys-
tem for the Mo-bound PPh2 groups and a sharp singlet
Ž
.
for the Zr-bound PMe3 ligand Table 1 .
While the AB system collapses to a singlet upon
warm up coalescence at 240 K , the PMe3 signal
remains virtually unaffected, even in the presence of
The stereochemistry of the reaction described by Eq.
4 deserves some comment. While the starting com-
Ž
.
Ž .
pound 5b is a 1:1 mixture of two diastereoisomers, the
corresponding product 6b is obtained as a single isomer.
Two explanations might be given for this observation.
First, the mobility of the coordination sphere around
zirconium allows for a ready site exchange of the
cyclohexyne and trimethylphosphine ligands, with one
w
x
added PMe3. Simulation of the spectra 17,18 applying
w
x
a two-site exchange model 19 yields a free energy of
Ž
.
activation of 40"8 kJrmol. Similar observations can
be made for 6b whose Mo-bound PPh2 groups are
exchange-equivalent at ambient temperature but become

(
)
86
W.A. Schenk, T. GutmannrJournal of Organometallic Chemistry 552 1998 83–89
Scheme 1.
Scheme 2.
diastereomer being strongly favored. Given the small
size of PMe3 and the quite large separation of the two
metal centers, this seems to be quite unlikely. Secondly,
the intermediate, coordinatively unsaturated zirconium-
2
cyclohexyne complex is temporarily stabilized by a
Zr–OC–Mo bridge which is opened stereospecifically
Ž
.
upon addition of PMe3 Scheme 2 .
Ligand substitution reactions at both d0 and d2-
zirconocene complexes are known to proceed by an
w
x
associative mechanism 22,23 . However, the question
of the stereochemical course has, to our knowledge, not
yet been addressed.
Ž .
5
2 Zirconocene-alkyne complexes without additional ligands have
Ž
w
x.
recently been characterized Refs. 20,21 .

(
)
W.A. Schenk, T. GutmannrJournal of Organometallic Chemistry 552 1998 83–89
87
Protonation of 6a using the weak Broenstedt acid
ordinating solvents led to decomposition instead of the
w
x
w
x
PhMe2 NH BPh4 in THF gives the cationic cyclohex-
expected formation of a Zr–OC–Mo bridge 24,25 .
Apparently, the electron density at the oxygen atoms of
a formally neutral molybdenum tetracarbonyl is not
high enough for the formation of a stable zirconium–
oxygen linkage, even in the presence of two C5H4 PPh2
ligands acting as additional braces.
Ž
Ž ..
enyl complex 7 Eq. 5 .The vacant coordination site
thus created at zirconium takes up a molecule of THF
rather than a Mo-bound carbonyl group. This is appar-
Ž
.
ent from the IR spectrum in the n CO region which
shows the typical pattern of an unperturbed cis-
w
Ž
.
x
Mo CO moiety. Carrying out the reaction in non-co-
4
Ž .
6
Zirconocene alkyne complexes undergo a variety of
insertion reactions with alkenes, alkynes, aldehydes,
narrow AB systems arising from the addition products
8a–c, respectively. Any attempts at their isolation, how-
ever, led to extensive decomposition, inter alia to the
w x
ketones, nitriles, and other unsaturated systems 8 . 6a
w
Ž
. ŽŽ .x
. Ž
similarly adds styrene, 4-chlorostyrene or norbornadiene
zirconium-free complex Mo CO Ph2 P C10 H10
4
2
31
Ž
Ž ..
w
x
as shown by P NMR Eq. 6 . Within 1 h at room
1,26 .
temperature, the singlet of 6a is cleanly replaced by
Ž .
7

(
)
88
W.A. Schenk, T. GutmannrJournal of Organometallic Chemistry 552 1998 83–89
Perfectly stable cycloadducts, however, were formed
temperature, the solvent is removed under vacuum and
the remaining residue is washed with pentane until a
brown powder is obtained. This is dissolved in benzene,
the solution is filtered over Celite, and the product
isolated after evaporation. Yield: 0.37 g 63% , brown
microcrystalline powder. Anal. found: C, 61.00; H,
Ž
Ž ..
in the reaction of 6a with ketones Eq. 7 . 9a–c are
yellow air-stable, crystalline solids. Their 1H NMR
spectra show signals for all groups present in the ex-
pected intensity ratio. The unsymmetrical coordination
environment of the zirconium center is evident from the
nonequivalence of all four protons of each CpX ligand as
well as the diastereotopicity of the benzylic protons of
9b. In the 13C NMR spectra all signals can be readily
assigned. Conclusive evidence for the proposed consti-
tution of 9a–c comes from two signals at 160 and 185
ppm which are typical for zirconium-bound vinyl groups
Ž
.
Ž
.
5.31. C50 H60Cl2 Li2O4 P2 Zr 962.98 calcd.: C, 62.36;
H, 6.28.
4.2. Reaction of 2 with diphenyldisulfide
Ž
.
Ž
A solution of 2 0.13 g, 0.14 mmol in benzene 15
.
Ž
ml is treated with diphenyldisulfide 30 mg, 0.14
mmol . After 20 min, the solution is filtered and par-
w
x
16 . Compared to the alkene adducts 8a–c it is cer-
.
tainly the thermodynamic strength of the Zr–O bond
tially evaporated and the product precipitated by adding
31
which adds to the stability of 9a–c.
pentane. NMR analysis 1H, P reveals the formation
Ž
.
w x
of two products, the major one being the dithiolate 3 1 .
3. Conclusions
X
[
(
)
(
) ] ( )
4.3. Cp2 Zr t-BuNC 2 Mo CO 4
4
The chemistry of PPh2-substituted zirconocenes as
well as their ligand-bridged binuclear derivatives does
not always mirror that of the parent C5H5 complexes.
Likely reasons for this different behavior are the shield-
ing of the coordination sphere of zirconium by the large
PPh2 groups and the reduction of the flexibility of the
complex brought about by tying the C5H4 PPh2 ligands
to a second metal atom. Nevertheless, binuclear d2–d6
systems are readily accessible and, by and large, exhibit
the expected reactivity pattern. In addition, the presence
of a suitably substituted d6-metal center seems to offer a
chance to gain some insight into the stereochemistry of
ligand substitution reactions at pseudotetrahedral metal-
locene complexes.
Ž
.
To a solution of 2 0.10 g, 0.10 mmol in benzene
Ž
w
.
2 .0 m l
is a d d e d a t ro o m
Mo CO norbornadiene
after 2 min, tert-butyl isonitrile 50 ml, 0.55 mmol .
After 1 h, the mixture is taken to dryness and the
te m p .
Ž
. Ž
.
x
Ž
.
30 mg, 0.10 mmol and,
4
Ž
.
residue recrystallized from
a small amount of
Ž
.
benzenerpentane. Yield: 63 mg 65% , brownish-yel-
Ž
.
Ž
Ž
.
.
low crystalline powder, m.p. 778C dec. . IR Nujol :
y1
Ž .
Ž .
Ž
.
Ž .
2162 m , 2136 m cm
CN ; 2012 m , 1896 vs, br
cmy1 CO . Anal. found: C, 61.08; H, 4.82; N, 2.67.
C48 H46 MoN2O4 P2 Zr 964.01 calcd.: C, 59.80; H, 4.81;
N, 2.91.
Ž
.
Ž
.
X
[
(
)(
)
(
) ] (
)
4.4. Cp2 Zr PMe3 C6 H8 Mo CO 4 6a
Ž
.
Ž
To a solution of 5a 0.17 g, 0.20 mmol in THF 5.0
4. Experimental
.
ml are added at y708C cyclohexenyllithium in ether
All manipulations were carried out in Schlenk-type
glassware under an atmosphere of purified nitrogen or
argon. Solvents were dried and distilled under nitrogen
prior to use. NMR solvents were degassed and stored
under nitrogen over molecular sieves. NMR: Bruker
Ž
.
Ž
.
0.20 mmol and PMe3 0.20 ml, 2.20 mmol . Upon
warming to room temperature some gas evolution is
observed. The product is isolated by filtration, partial
evaporation, and careful addition of pentane. Yield:
0.15 g 79% , brownish-yellow crystalline powder, m.p.
858C dec. . IR Nujol : 2013 m , 1915 s , 1897 vs ,
Ž
.
AMX 400; chemical shifts are reported in ppm vs. TMS
Ž
.
Ž
.
Ž . Ž .
Ž .
13
Ž
.
Ž31
.
1H, C and 85% H3PO4
P . IR: Bruker IFS 25,
y1
Ž
.
Ž
.
1873 sh cm
CO . Anal. found: C, 59,47; H, 4.92.
C47 H45MoO4 P3Zr 953.96 calcd.: C, 59.18; H, 4.75.
Perkin-Elmer 283.
The following starting materials were prepared by
Ž .
Ž
.
X
published procedures: CpX2 ZrCl 2
1
[
(
)(
)
(
)
] (
)
w x
27 ,
4.5. Cp2 Zr PMe3 C6 H8 Mo CO 3 PMe3 6b
w
w
w
Ž
. Ž
.
x
w
x
w
x
M o CO norbornadiene
28 , PM e3 29 ,
4
This compound was obtained from 5b as described
above. Yield: 0.17 g 86% , brownish-yellow crystalline
x
w
x
w
x
P h M e 2 N H B P h
Cp2 Zr Cl Me Mo CO L L5CO 5a , PMe3 5b
1 . All other reagents were used as obtained commer-
3 0 , L iC 6 H
Ž
1 6 ,
4
9
Ž
.
X
Ž
.Ž
.
Ž
.
x
Ž
.
Ž
..
3
Ž
.
Ž
.
Ž .
Ž .
powder, m.p. 638C dec. . IR Nujol : 1933 s , 1830 vs
w x
cmy1 CO . Anal. found: C, 59,70; H, 5.28.
Ž
.
cially.
Ž
.
C49 H54 MoO3P4 Zr 1002.02 calcd.: C, 58,74; H, 5.43.
X
( )
4.1. Cp2 ZrP2 LiClP4 THF 2
X
[
(
)(
)
(
) ]
( )
7
4.6. Cp2 Zr THF C6 H9 Mo CO 4 BPh4
To a solution of CpX2 ZrCl2 0.40 g, 0.61 mmol in
Ž
.
Ž
.
Ž
.
Ž
Ž
THF 20 ml is added at y708C a solution of n-butyl-
To a solution of 6a 0.24 g, 0.24 mmol in THF 10.0
Ž
.
.
lithium in hexane 0.8 ml, 2.0 mmol . The reaction
mixture turns dark immediately. After 15 h at room
ml is added dimethylanilinium tetraphenylborate 0.11
g, 0.25 mmol at y708C. The mixture is allowed to
.

(
)
W.A. Schenk, T. GutmannrJournal of Organometallic Chemistry 552 1998 83–89
89
Ž
.
warm to y208C and the product is isolated after cold
61.98; H, 4.54. C50 H46 MoO5P2 Zr 976.02 calcd.: C,
61.53; H, 4.75.
filtration and partial evaporation by adding pentane.
Ž
.
Yield: 0.19 g 63% , brownish-yellow crystalline pow-
13
Ž
.
Ž
.
der, m.p. 1268C dec. . C NMR 100 MHz, CD2Cl2 :
ds25.4, 25.5, 27.8, 35.5 s, CH2 , 25.9, 68.6 s,
Ž
.
Ž
Acknowledgements
.
Ž
.
THF , 114.3, 116.2, 118.0, 122.8, 123.7 s, br, C5H4 ,
122.2, 126.1, 128.4, 128.7, 130.0, 130.7, 133.2, 134.3,
We are indebted to the Deutsche Forschungsgemein-
schaft and the Fonds der Chemischen Industrie for the
generous support of this work.
Ž
.
Ž
136.3, 137.8, 138.3 phenyl resonances , 138.7 s,
1
.
Ž
Ž
.
.
Ž
C5C–Zr , 164.4 q, J C–B s37 Hz, B–C , 191.6 s,
2
.
Ž
Ž
.
.
Ž
C5C–Zr , 210.2, t, J P–C s9 Hz, CO , 210.8 t,
2
Ž
.
.
Ž
J P–C s9 Hz, CO , 214.6 t, outer lines not re-
y1
.
Ž
.
Ž .
Ž
.
solved, CO . IR Nujol : 2016 m , 1898 vs, br cm
References
Ž
.
CO . Anal. found: C, 68.29; H, 5.03.
Ž
.
C72 H65BMoO5P2 Zr 1270.23 calcd.: C, 68.08; H, 5.16.
w x
Ž
.
.
1
W.A. Schenk, T. Gutmann, J. Organomet. Chem. 544 1997
69.
X
w x
Ž .
2
W.A. Schenk, C. Labude, Chem. Ber. 122 1989 1489.
[
(
)
(
) ] (
)
4.7. Cp2 Zr OCPh2C6 H8 Mo CO 4 9a
w x
Ž
3
W.A. Schenk, C. Neuland-Labude, Z. Naturforsch., B 46 1991
573.
Ž
.
To a solution of 6a 0.10 g, 0.10 mmol in benzene
w x
4
D.J. Cardin, M.F. Lappert, C.L. Raston, Chemistry of Organo-
Zirconium and -Hafnium Compounds, Ellis Horwood, Chich-
ester, 1986, p. 288.
Ž
.
Ž
.
5.0 ml is added benzophenone 20 mg, 0.11 mmol .
After stirring 2 h at room temperature, the solution is
partially evaporated and the product precipitated by
w x
5
G. Erker, C. Kruger, G. Muller, Adv. Organomet. Chem. 24
¨ ¨
Ž
.
1985 1.
Ž
.
adding pentane. Yield: 87 mg 82% , yellow crystalline
w x
Ž
.
6
H. Yasuda, A. Nakamura, Angew. Chem. 99 1987 745.
13
Ž
.
Ž
.
powder, m.p. 1338C dec. . C NMR 100 MHz, C6 D6 :
w x
7
H. Yasuda, A. Nakamura, Angew. Chem., Int. Ed. Engl. 26
Ž
.
Ž
.
ds23.7, 25.0, 32.1, 35.5 s, CH2 , 95.3 s, OCPh2 ,
Ž
.
1987 723.
Ž
.
w x
Ž
.
110.9, 118.9, 119.3, 120.3, 121.1 s, br, C5H4 , 132–140
8
S.L. Buchwald, R.B. Nielsen, Chem. Rev. 88 1988 1047.
w x
9
E. Negishi, F.E. Cederbaum, T. Takahashi, Tetrahedron Lett. 27
Ž
.
Ž
.
Ž
m, phenyl resonances , 158.9 s, C5C–Zr , 185.0 t,
outer lines not resolved, C5C–Zr , 211.0 t, J P–C
2
Ž
.
1986 2829.
.
Ž
Ž
.
w
w
w
w
w
w
x
Ž
.
10 E. Negishi, T. Takahashi, Acc. Chem. Res. 27 1994 124.
.
Ž
.
s9 Hz, CO , 213.9 t, outer lines not resolved, CO .
x
Ž
.
11 G. Erker, Acc. Chem. Res. 17 1984 103.
Anal. found: C, 64.07; H, 4.29. C57 H46 MoO5P2 Zr
x
Ž
.
12 D.W. Stephan, Organometallics 11 1992 996.
Ž
.
x
Ž
.
1060.10 calcd.: C, 64.58; H, 4.37.
13 J. Ren, J. Guan, S. Jin, Q. Shen, Polyhedron 13 1994 2979.
x
Ž
.
14 G. Lin, W.-T. Wong, Polyhedron 13 1994 3027.
X
x
15 S.L. Buchwald, B.T. Watson, J.C. Huffman, J. Am. Chem. Soc.
[
(
(
)
)
(
) ] (
)
4.8. Cp2 Zr OC CH2 Ph 2C6 H8 Mo CO 4 9b
Ž
.
109 1987 2544.
w
x
16 S.L. Buchwald, R.T. Lum, J.C. Dewan, J. Am. Chem. Soc. 108
This compound was obtained from 6a and dipheny-
Ž
.
1986 7441.
Ž
.
w
w
x
Ž
.
lacetone as described above. Yield: 84 mg 77% , yel-
17 G. Binsch, H. Kessler, Angew. Chem. 92 1980 445.
low crystalline powder, m.p. 978C dec. . 13C NMR
x
Ž
.
.
18 G. Binsch, H. Kessler, Angew. Chem., Int. Ed. Engl. 19 1980
Ž
.
411.
Ž
.
Ž
.
100 MHz, C6 D6 : ds23.7, 25.3, 30.0, 35.2 s, CH2 ,
w
w
w
w
w
w
w
x
Ž
19 M.L.H. Green, L. Wong, A. Sella, Organometallics 11 1992
2660.
Ž
.
Ž
Ž
. .
45.0 s, CH2 Ph , 94.0 s, OC CH2 Ph , 113.0, 118.6,
2
Ž
Ž
.
.
Ž
118.9, 120.2, 121.6 s, br, C5H4 , 132–140 m, phenyl
x
20 C. Lefeber, W. Baumann, A. Tillack, R. Kempe, H. Gorls, U.
¨
.
Ž
.
Ž
.
resonances , 157.4 s, C5C–Zr , 185.3 s, C5C–Zr ,
Rosenthal, Organometallics 15 1996 3572.
2
2
x
21 J. Hiller, U. Thewalt, M. Polasek, L. Petrusova, V. Varga, P.
Ž
Ž
.
.
Ž
Ž
.
210.7, t, J P–C s8 Hz, CO , 212.1 t, J P–C s8
Ž
.
Sedmera, K. March, Organometallics 15 1996 3752.
.
Ž
.
Hz, CO , 214.2 t, outer lines not resolved, CO . Anal.
x
22 R. bin Ali, J. Burgess, A.T. Casey, J. Organomet. Chem. 362
Ž
.
found: C, 65.12; H, 4.20. C59 H50 MoO5P2 Zr 1088.15
Ž
.
1989 305.
calcd.: C, 65.12; H, 4.63.
x
23 G.T. Palmer, F. Basolo, L.B. Kool, M.D. Rausch, J. Am. Chem.
Ž
.
Soc. 108 1986 4417.
X
x
24 B. Longato, B.D. Martin, J.R. Norton, O.P. Anderson, Inorg.
[
(
)
(
) ] (
)
4.9. Cp2 Zr OC6 H10C6 H8 Mo CO 4 9c
Ž
.
Chem. 24 1985 1389.
x
25 G.M. Dawkins, M. Green, K.A. Mead, J. Salaun, F.G.A. Stone,
This compound was obtained from 6a and cyclohex-
Ž
.
P. Woodward, J. Chem. Soc., Dalton Trans. 1983 527.
Ž
.
anone as described above. Yield: 66 mg 68% , yellow
w
w
x
x
Ž
.
26 W.-K. Wong, F.-W. Lee, Polyhedron 11 1992 863.
27 W. Tikkanen, Y. Fujita, J.L. Petersen, Organometallics 5 1986
13
Ž
.
Ž
Ž
.
crystalline powder, m.p. 1088C dec. . C NMR 100
888.
.
.
MHz, C6 D6 : ds21.2, 23.1, 24.9, 25.3, 27.5, 33.9,
w
w
w
x
28 R.B. King, Organometallic Synthesis, Academic Press, New
York, 1985, p. 124.
Ž
Ž
.
34.3 s, CH2 , 89.2 s, OCC5H10 , 109.6, 117.2, 117.6,
Ž
.
.
Ž
119.6, 119.8, s, br, C5H4 , 131–139 m, phenyl reso-
nances , 160.4 s, C5C–Zr , 178.9 s, C5C–Zr , 209.2,
209.9, 213.1 t, not resolved, CO . Anal. found: C,
x
29 W. Wolfsberger, H. Schmidbaur, Synth. React. Inorg. Met.-Org.
.
Ž
Ž
.
Ž
.
Chem. 4 1974 149.
Ž
.
x
Ž
.
30 F.E. Crane, Anal. Chem. 28 1956 1794.