Synthesis, structure, and reactivity of 2-phosphabenzyne-zirconocene dimers

Article abstract of DOI:10.1021/ja971679i

The extrusion of methane from (2-phosphininyl)(methyl) zirconocenes 3a-c at 80°C in benzene affords the corresponding ²-phosphabenzyne-zirconocene dimers 4a-c, one of which has been characterized by X-ray crystal structure analysis. The parameters of the C-C-Zr three-membered ring are exactly similar to those found in the ²-benzyne-zirconocene complex: C-C, 1.361(2); C-Zr, 2.238 and 2.250(2) A?. The P-Zr distances are normal at 2.6857(5) and 2.6922(5) A?. The reaction of these ²-phosphabenzyne complexes with acetonitrile, Ph₃P=S, (diphenylphosphino)- and (trimethylsilyl)alkynes, aldehydes, and (+)-camphor have been investigated. In all cases, an insertion into the C₂-Zr bond is observed. Hydrolysis of the intermediate zirconacycles thus obtained yielded several new 2-functional phosphinines, including a thiol (6), a vinylphosphine (8), two secondary alcohols (14 and 15), and an homochiral phosphinine-substituted alcohol (17). The regiospecificity of the insertion is ascribed to the huge concentration of negative charge at the α-position of the phosphinine ring.

Full text of DOI:10.1021/ja971679i

J. Am. Chem. Soc. 1997, 119, 9417-9423
9417
Synthesis, Structure, and Reactivity of
η2-Phosphabenzyne-Zirconocene Dimers
Patrick Rosa, Pascal Le Floch, Louis Ricard, and Franc¸ois Mathey*
Contribution from the Laboratoire “He´te´roe´le´ments et Coordination”, URA CNRS 1499,
Ecole Polytechnique, 91128 Palaiseau Cedex, France
ReceiVed May 22, 1997X
Abstract: The extrusion of methane from (2-phosphininyl)(methyl) zirconocenes 3a-c at 80 °C in benzene affords
the corresponding η2-phosphabenzyne-zirconocene dimers 4a-c, one of which has been characterized by X-ray
crystal structure analysis. The parameters of the C-C-Zr three-membered ring are exactly similar to those found
in the η2-benzyne-zirconocene complex: C-C, 1.361(2); C-Zr, 2.238 and 2.250(2) Å. The P-Zr distances are
normal at 2.6857(5) and 2.6922(5) Å. The reaction of these η2-phosphabenzyne complexes with acetonitrile, Ph3PdS,
(diphenylphosphino)- and (trimethylsilyl)alkynes, aldehydes, and (+)-camphor have been investigated. In all cases,
an insertion into the C2-Zr bond is observed. Hydrolysis of the intermediate zirconacycles thus obtained yielded
several new 2-functional phosphinines, including a thiol (6), a vinylphosphine (8), two secondary alcohols (14 and
15), and an homochiral phosphinine-substituted alcohol (17). The regiospecificity of the insertion is ascribed to the
huge concentration of negative charge at the R-position of the phosphinine ring.
Introduction
at zirconium followed by a thermolysis of the resulting Zr-
Me complexes turns out to be the best approach to the
corresponding η2-(2,3-didehydrophosphinine) complexes (eq 1).
Heteroarynes are unstable intermediates which have found
numerous uses in organic synthesis,1 but whose characterization
has remained difficult.2 Their stabilization as metal complexes
is thus an attractive goal. For some time now, Erker, Buchwald,
and others have developed the chemistry of η2-benzyne-
zirconium complexes.3 These reactive species are stable enough
for structural characterization by X-ray analysis.4 It was thus
tempting to transpose this approach to heteroarynes. Unfortu-
nately, an insertion of zirconocene into the carbon-heteroatom
bond was observed with furan and thiophene instead of
CtC bond complexation.5 In contrast, more recently, we have
been able to synthesize a η2-phosphabenzyne-zirconocene
which is stable enough for in situ characterization by NMR
spectroscopy.6 Hereafter, we build on this preliminary result
and describe the successful characterization of more stable η2-
phosphabenzyne-zirconocene dimers and several features of
their reactivity.
(1)
Results and Discussion
Bromozirconium(IV) complexes 2 resulting from the insertion
of zirconocene into the C-Br bond of 2-bromophosphinines
are suitable precursors for the preparation of η2-phosphaben-
zyne-zirconocene complexes.7 By following a similar meth-
odology as that developed for benzyne complexes, methylation
X Abstract published in AdVance ACS Abstracts, September 15, 1997.
(1) Review: Reinecke, M. G. Tetrahedron 1982, 38, 427.
(2) Recent developments on 3,4-didehydropyridine and thiophene: Nam,
H. H.; Leroi, G. E. J. Am. Chem. Soc. 1988, 110, 4096; Ye, X.-S.; Li.;
Wong, H. N. C. J. Am. Chem. Soc. 1996, 118, 2511.
(3) Erker, G. J. Organomet. Chem. 1977, 134, 189. Buchwald, S. L.;
Nielsen, R. B. Chem. ReV. 1988, 88, 1047 (review).
All of this sequence can be carried out using a one-pot procedure
since complexes 2 and 3, which are very sensitive toward
moisture, need not be isolated. Whereas monomeric species
are formed when the extrusion of methane is carried out in the
presence of trimethylphosphine,6 dimeric species are obtained
(4) Buchwald, S. L.; Watson, B. T.; Huffman, J. C. J. Am. Chem. Soc.
1986, 108, 7411. For other structurally characterized η2-benzyne complexes,
see: McLain, S. J.; Schrock, R. R.; Sharp, P. R.; Churchill, M. R.; Youngs,
W. J. J. Am. Chem. Soc. 1979, 101, 263. Benett, M. A.; Hambley, T. W.;
Roberts, N. K.; Robertson, G. B. Organometallics 1985, 4, 1992.
(5) Erker, G.; Petrenz, R.; Kru¨ger, C.; Lutz, F.; Weiss, A.; Werner, S.
Organometallics 1992, 11, 1646.
(6) Le Floch, P.; Kolb, A.; Mathey, F. J. Chem. Soc., Chem. Commun.
1994, 2065.
(7) Le Floch, P.; Ricard, L.; Mathey, F. J. Chem. Soc. Chem.,Commun.
1993, 789.
S0002-7863(97)01679-X CCC: $14.00 © 1997 American Chemical Society

9418 J. Am. Chem. Soc., Vol. 119, No. 40, 1997
Rosa et al.
The chemistry of these η2-phosphabenzyne complexes was
studied either with dimer 4b or with freshly prepared THF
solutions of precursors 3a,b (see Experimental Section). A first
interesting remark concerns the reaction of dimers with PMe3.
Even under forcing conditions (excess of PMe3 in boiling THF
or benzene), the dimeric structure of 4b is not destroyed and
formation of the PMe3-complexed monomer is never observed,
thus confirming that the phosphinine P-Zr bonds are strong.
More useful results were obtained with polar molecules. Two
new reactions were first investigated. Both 3b and 4b easily
react with acetonitrile to give selectively an insertion product
into the C2-Zr bond (eq 2).
Figure 1. ORTEP drawing of one molecule of 4b. Ellipsoids are scaled
to enclose 50% of the electron density. Hydrogen atoms are omitted
for clarity. Selected bond distances (Å): Zr(1)-P(1), 2.6922(5); Zr-
(2)-P(9), 2.6857(5); Zr(2)-C(2), 2.238(2); Zr(2)-C(3), 2.250(2);
P(1)-C(2), 1.696(2); P(1)-C(6), 1.729(2); C(2)-C(3), 1.361(2); C(3)-
C(4), 1.404(2); C(4)-C(5), 1.414(3); C(5)-C(6), 1.405(3). Selected
bond angles (deg): P(1)-Zr(1)-C(10), 70.95(4); Zr(1)-P(1)-C(2),
125.31(6); Zr(1)-P(1)-C(6), 133.07(7); Zr(2)-C(2)-C(3), 72.8(1);
Zr(2)-C(3)-C(2), 71.9(1); Zr(2)-C(2)-P(1), 163.1(1); Zr(2)-C(3)-
C(4), 160.0(1); C(2)-P(1)-C(6), 101.59(9); P(1)-C(2)-C(3), 124.0-
(1); C(2)-C(3)-C(4), 127.1(2); C(3)-C(4)-C(5), 119.5(2); C(4)-
C(5)-C(6), 122.4(2); P(1)-C(6)-(C5), 125.2(1).
Complex 5 has been identified by a combination of NMR
experiments, mass spectrometry, and elemental analysis. The
regiospecificity of the insertion was easily demonstrated upon
inspection of the 13C NMR spectrum of 5 which displays a
2
characteristic CdN resonance at 191.45 with a huge J(C-P)
in the absence of phosphine. The dimer 4a derived from [Zr-
(C5H5)2] and 2-bromo-4,5-dimethylphosphinine (1) proved to
be stable but only poorly soluble in inert organic solvents. To
get satisfactory crystals for X-ray analysis, we duplicated the
same synthesis with 1,1′-dimethyl- and 1,1′-bis(trimethylsilyl)-
zirconocenes (eq 1).
coupling constant at 40.55 Hz. Unfortunately, attempted
hydrolysis of 5 to obtain the 2-acetyl derivative has failed so
far.
A selective cleavage of the C2-Zr bond was also observed
when using triphenylphosphine sulfide as a sulfur donor. Dimer
4b readily reacts with Ph3PdS in THF at 80 °C to give a poorly
soluble intermediate which was only characterized by 31P NMR
(δ ) 185.35 (THF) with 2J(P-H) ) 39.45 Hz) and free
triphenylphosphine. Upon hydrolysis with HCl, the original and
interesting thiol 6 is formed (eq 3).
Due to its poor solubility, dimer 4a was only characterized
1
by H and 31P NMR spectroscopy, mass spectrometry, and
elemental analysis. The characterization of the dimethyl- and
bis(trimethylsilyl) derivatives 4b,c also included their 13C NMR
spectra as a result of their higher solubility. The most interesting
features of these 13C spectra concern the strongly deshielded
C2 and C3 resonances of the phosphinine ring. For 4b (in
CDCl3) as an example, the C2 resonance appears as a pseudo-
triplet at 184.75, ∑ J(C-P) ) 86.0 Hz, whereas C3 is found at
186.20, ∑ J(C-P) ) 47.20 Hz. These values can be compared
with that of C6, δ 155.40, ∑ J(C-P) ) 39.85 Hz, which appears
in the normal range for any phosphinine derivative. Another
interesting comparison can be drawn with the resonances of
the benzyne carbons in [Zr(η2-C6H4)(η5-C5H5)2(PMe3)] which
appear at δ 174.30.4
An ORTEP view of 4b is presented in Figure 1. The
geometry of the ZrC(2)C(3) metallacycle in 4b is remarkably
similar to that of the η2-benzyne-zirconocene complex. The
opening of the C-Zr-C angles are quite similar at 35.29(6)
and 35.33(6)°, respectively. The Zr-C bonds are found at
2.238(2) and 2.250(2) Å in 4b vs 2.228(5) and 2.267(5) Å in
the benzyne complex. Obviously, the inclusion of phosphorus
in the six-membered ring does not disturb the coordination
sphere of zirconium. Even the Zr-P distances fall in the same
range: Zr-phosphinine 2.6857(5) and 2.6922(5) Å vs 2.687-
(3) Å for Zr-PMe3, although phosphinine is known to be a
much weaker donor than trimethylphosphine. More severe
distortions are seen when comparing the structure of 4b with
that of a σ-precursor such as 2a (Br replaced by Cl).7 The C2-
C3 bond is shortened from 1.395(6) Å in 2a to 1.361(2) Å in
4b. Whereas the P-C(6) bond remains unchanged at 1.729(2)
Å, the P-C(2) distance decreases in 4b at 1.696(2) Å.
Otherwise, the structure of the phosphinine ring is not signifi-
cantly perturbed.
1
The H NMR spectrum of 6 shows one R- and one â-H
resonances, thus establishing the insertion of sulfur into the C2-
Zr bond of 4b. In CDCl3, the SH group appears as a doublet
at 4.04 with a 3J(H-P) coupling of 8.90 Hz, implying that the
proton exchange is slow on the NMR time scale.
In our previous report,6 we presented several examples of
reactions of our η2- phosphabenzyne-PMe3 complex with
alkynes and ketones. Insertion into the C2-Zr bond was always
observed with formation of five-membered zirconacycles.
Hereafter, we describe several additional examples of such
reactions. In very recent reports, Majoral et al. showed that
the insertion of phosphinoalkyne8a and vinylphosphine8b into
the reactive C-Zr bonds of η2-benzyne-zirconocene exclu-
sively gives the regioisomer where the phosphino substituent
is located on the R-position of the five-membered zirconacycle,
probably as a result of an initial interaction between phosphorus
and zirconium. The reaction of phenethynyldiphenylphosphine
with 3a affords two insertion complexes 7R and 7â in a 95:5
ratio (eq 4).
(8) (a) Miquel, Y.; Igau, A.; Donnadieu, B.; Majoral, J.-P.; Dupuis, L.;
Pirio, N.; Meunier, P. J. Chem. Soc., Chem. Commun. 1997, 279. (b)
Zablocka, M.; Ce´nac, N.; Igau, A.; Donnadieu, B.; Majoral, J. P.;
Skowronska, A.; Meunier, P. Organometallics 1996, 15, 5436.

η2-Phosphabenzyne-Zirconocene Dimers
J. Am. Chem. Soc., Vol. 119, No. 40, 1997 9419
Both hydrolysis products 14 and 15 display characteristic
CH-O resonances in their 13C spectra (CDCl3). 14: δ(CH)
74.55, 2J(C-P) ) 35.55 Hz. 15: δ(CH) 75.15, 2J(C-P) ) 32.20
Hz. The magnitude of these J(C-P) coupling and the presence
of one R-H (H6) resonance in each 1H spectrum unambiguously
demonstrate the R-substitution.
In a very recent report, Breit underlined the potential use of
phosphinines as ligands in homogeneous catalysis.9 In such a
context, the synthesis of homochiral phosphinines for enanti-
oselective catalysis becomes a very attractive challenge. As
an outcome of the chemistry of η2-phosphabenzyne-zir-
conocenes, we can propose a simple access to one type of such
molecules. The reaction of (+)-camphor with 3a which
proceeds very slowly, probably as a result of an important steric
crowding during the formation of the intermediate metallacycle
16, gives a single diastereomer in 55% overall yield after
hydrolysis (eq 7).
Both the major and minor isomers 7R and 7â were character-
ized by their 31P NMR spectrum. 7r: δ 31P + 200.45 and
-19.95 (THF), 4J(P-P) ) 12.70 Hz. 7â: δ 31P + 202.10 and
-8.25 (THF), 3J(P-P) ) 96.50 Hz. The magnitude of the J(P-
P) constant strongly suggests that the regiochemistry of the
insertion is identical in 7R to that observed with η2-benzyne-
zirconocene complex. Upon hydrolysis, only the phosphinine
8 derived from 7R could be detected. Two significant NMR
data confirm the structure of 8. First, only one R-H (H6)
resonance is observed in the 1H NMR spectrum, thus showing
the initial insertion of the alkyne into the C2-Zr bond. Second,
in the 31P NMR spectrum, the absence of J(P-P) coupling
confirms that the carbon bearing the diphenylphosphino group
was initially bound to the metal. A clear-cut result was also
observed with another polar alkyne such as (trimethylsilyl)-
acetylene (eq 5).
The structure of 17 was ascertained by X-ray crystal structure
analysis of its P-W(CO)5 complex 18. An ORTEP view of
18 is presented in Figure 2. The latter indicates that the
phosphinine ring was selectively grafted onto the endo position
of the norbornane skeleton giving enantiomerically pure 17. This
result can be easily rationalized in terms of stericity if one
acknowledges that the formation of the other possible diaste-
reomer of 16 is strongly disfavored because of important steric
hindrance between the phosphinine and the two methyl groups
of the bridge.
As a general conclusion of this study, it can be confidently
stated that the chemistry of η2-phosphabenzyne-zirconocene
complexes closely mimics that of its η2-benzyne counterpart.
The only question which remains to be addressed concerns the
extraordinary regiospecificity of the insertion reactions into the
C2-Zr bond. If we take the insertion of alkynes as a model
reaction, we can acknowledge as usual that the first step of the
mechanism is the formation of an η2-alkyne-zirconium com-
plex. The second step can be viewed as an intramolecular
nucleophilic attack of C2 (or C3) onto the coordinated alkyne.
It can be argued that steric effects may be at the origin of
this regiochemical preference if we consider that the presence
of the methyl group at the C4 position will disfavor the insertion
of the alkyne into the C3-Zr bond by hindering its approach to
zirconium. Similar effects have been been reported by Bu¨ch-
wald et al. during their studies on substituted benzyne com-
plexes.13 Although probably non-negligible, we feel that this
The insertion takes place into the C2-Zr bond as usual, and
the trimethylsilyl group is located on the R-carbon of the
resulting five-membered ring as observed for the insertion
product of η2-benzyne-zirconocene complex.3b This regio-
chemistry is unambigously established by the vinyl H resonance
in 9 which appears at 7.64, 3J(H-P) ) 8.85 Hz, in the 1H NMR
spectrum and by the corresponding 13C resonance at 136.85
which exhibits a strong 2J(C-P) coupling of 49.10 Hz.
Phosphinine 9 which is slightly oxygen-sensitive was also
characterized as its P-W(CO)5 complex.
In our previous report, we did not investigate the reactivity
of η2-phosphabenzyne-zirconocene-(PMe3) complexes toward
aldehydes. As expected, the insertion selectively takes place
into the C2-Zr bond (eq 6).
(9) Breit, B. J. Chem. Soc., Chem. Commun. 1996, 2071.
(10) Nyulaszi, L.; Keglevich, G. Heteroatom. Chem. 1994, 5, 131.
(11) Hengefeld, A.; Nast, R. Chem. Ber. 1983, 116, 2035.
(12) Samuel, E. Bull. Soc. Chim. Fr. 1966, 3548.

9420 J. Am. Chem. Soc., Vol. 119, No. 40, 1997
Rosa et al.
chlorotrimethylsilane were added to neutralize any excess of n-
butyllithium. The solution was allowed to stir for a few minutes at
-78 °C before 2-bromophosphinine 1 (5.05 g, 25 mmol) was added.
The reaction mixture was then quickly warmed to room temperature
and stirred for 30 min at 40 °C.
A
31P NMR control showed the
unambiguous formation of complex 2a. Methyllithium (15.6 mL, 25
mmol, solution 1.6 M in diethyl ether) was then added dropwise at
-78 °C. The reaction mixture was warmed slowly to room temperature,
and the transformation of complex 2a into complex 3a was controlled
by 31P NMR. The solvents were evaporated in vacuo, and the resulting
brown oil was dissolved in benzene (100 mL), filtrated, and then heated
at 80 °C. Formation of insoluble dimeric complex 4a could not be
followed by 31P NMR since it precipitated as soon as it formed. After
2 h of warming, the mixture was cooled to room temperature and dimer
4a was isolated by filtration under nitrogen. The yellow powder
obtained was washed successively with benzene (20 mL) and hexane
(40 mL) and then dried under reduced pressure. Yield: 6.00 g (70%).
2a: 31P NMR (THF) δ 224.40. 3a: 31P NMR (THF) δ 218.25. 4a:
1
31P NMR (CDCl3) δ 194.35; H NMR (CDCl3) δ 2.42 (s, 6H, Me),
2.60 (AXX′, 6H, Σ J(H-P) ) 7.90, Me), 5.50 (s, 20H, 4 × C5H5),
8.25 (AXX′, ∑ J(H-P) ) 22.80, H6,6′); mass spectrum, m/z (ion, relative
intensity) 687 (M, 15), 343 (M/2, 50). Anal. Calcd for C34H34P2Zr2:
C, 59.44; H, 4.99. Found: C, 59.31; H, 5.18.
Figure 2. ORTEP drawing of one molecule of 18. Ellipsoids are scaled
to enclose 50% of the electron density. The crystallographic labeling
is arbitrary and different from the numbering used for assignment of
the 13C spectra. Hydrogen atoms are omitted for clarity. Selected bond
distances (Å): W(1)-P(1), 2.525(2); P(1)-C(1), 1.740(5); C(1)-C(2),
1.383(7); C(2)-C(3), 1.40(1); C(3)-C(4), 1.387(8); C(4)-C(5), 1.412-
(7); C(5)-P(1), 1.743(6); C(5)-C(6), 1.544(8). Bond angles (deg):
C(1)-P(1)-C(5), 102.8(3); P(1)-(C1)-C(2), 126.4(5); C(1)-C(2)-
C(3), 121.7(5); C(2)-C(3)-C(4), 121.1(5); C(3)-C(4)-C(5), 129.1-
(6); C(4)-C(5)-P(1), 118.8(5); C(1)-P(1)-W(1), 115.3(2); C(5)-
P(1)-W(1), 141.8(2).
Synthesis of Dimer 4b. The experimental procedure is identical
with the one yielding dimer 4a. The insertion complex 2b was obtained
from (C5H4Me)2ZrCl2 (8.00 g, 25 mmol), butyllithium (31.25 mL, 1.6
M in hexane), and 2-bromophosphinine 1 (5.05 g, 25 mmol). After
checking the formation of complex 2b by 31P NMR, the mixture was
cooled to -78° and methyllithium (15.6 mL, 25 mmol) was added
dropwise. The solution was then warmed to room temperature. 31P
NMR showed the formation of complex 3b. Upon removal of the
solvents in vacuo, the brown oil obtained was dissolved in benzene
(100 mL), filtrated, and heated at 80 °C for 2 h. The unambiguous
formation of complex 4b could be followed by 31P NMR. The half-
part of solvent was removed under reduced pressure (30 mL), and the
resulting solution was left to stand for 2 h. After this period, the solid
that precipitated was isolated by filtration under nitrogen. The yellow
powder thus obtained was washed with hexane (50 mL) and dried in
effect is not decisive and it is clear that electronic effects must
also be taken into accounts. Indeed, it is well established that
the HOMO of phosphinines is mainly localized at P, CR (C2)
and Cγ (C4). Besides, it appears that there is a much larger
concentration of negative charge at CR than Câ (C3): CR, -0.54;
Câ, -0.22.10 Significantly, as shown in the structure of dimer
4b, the positively charged zirconium is closer to C2 than to C3.
Thus we can safely concede that C2 is more nucleophilic than
C3 in 4 and that the selective insertion into C2-Zr bond is fully
rational.
vacuo. Yield: 6.50 g (70%). 2b:
31P NMR (THF) δ 224.05. 3b:
31P NMR (THF) δ 218.40 (2J(H-P) ) 34.05, 3J(H-P) ) 14.50). 4b:
31P NMR (CDCl3) δ 195.15; 1H NMR (CDCl3) δ 1.23 (s, 12H, Me of
C5H4Me), 2.53 (s, 6H, Me of C7H7P), 2.69 (AXX′, 6H, ∑ J(H-P) )
6.05, Me of C7H7P), 5.47 (m, 8H, CH of C5H4Me), 5.62 (m, 4H, CH
of C5H4Me), 5.70 (m, 4H, CH of C5H4Me), 8.25 (AXX′, 2H, ∑ J(H-
P) ) 22.96, H6,6′); 13C NMR (CDCl3): δ 15.40 (s, Me of C5H4Me),
23.35 (s, Me of C7H7P), 23.70 (s, Me of C7H7P), 98.90 (s, CH of C5H4-
Me), 103.45 (s, CH of C5H4Me), 104.90 (s, CH of C5H4Me), 108.25
(s, CH of C5H4Me), 117.65 (s, Cq of C5H4Me), 139.45 (AXX′, ∑ J(C-
P) ) 31.00, C4 or C5 of C7H7P), 143.35 (AXX′, ∑ J(C-P) ) 19.55,
C5 or C4 of C7H7P), 155.40 (AXX′, ∑ J(C-P) ) 39.85, C6 of C7H7P),
184.75 (AXX′, ∑ J(C-P) ) 86.00, C2 of C7H7P), 186.20 (AXX′, ∑
J(C-P) ) 47.20, C3 of C7H7P); mass spectrum, m/z (ion, relative
intensity) 743 (M, 8), 371 (M/2, 30), 81 (C5H4Me + 2, 100). Anal.
Calcd for C38H42P2Zr2: C, 61.42; H, 5.70. Found: C, 61.77; H, 5.72.
Experimental Section
All reactions were routinely performed under an inert atmosphere
of nitrogen by using Schlenk techniques and dry deoxygenated solvents.
Dry THF, ether, benzene, toluene, hexane, and pentane were obtained
by distillation from Na/benzophenone, and dry CH2Cl2 and MeCN were
obtained by distillation from P2O5. Dry Celite was used for filtration.
Nuclear magnetic resonance spectra were obtained on a Bruker AC-
200 SY spectrometer operating at 200.13 MHz for 1H, 50.32 MHz for
13C, and 81.01 MHz for 31P. Chemical shifts are expressed in parts
per million downfield from external TMS (1H and 13C) and 85% H3-
PO4 (31P), and coupling constants are given in hertz. Mass spectra
were obtained at 70 eV with an HP 5989 B spectrometer coupled with
a HP 5890 chromatograph by the direct inlet method. The following
abreviations are used: s, singlet; d, doublet; t, triplet; q, quadruplet; p,
pintuplet; m, multiplet; b, broad. Elemental analyses were performed
by the “Service d’analyse du CNRS”, at Gif sur Yvette, France. Zr-
(C5H4Me)2Cl2 and Zr(C5H4SiMe3)2Cl2 were prepared by the reaction
of the corresponding cyclopentadienyllithium salts with ZrCl4 in THF
according to ref 12. Phenethynyldiphenylphosphine was prepared
according to a published procedure.11
Synthesis of Dimer 4c. The experimental procedure is identical
with the one yielding dimers 4a,b. The insertion complex 2c was
obtained from (C5H4SiMe3)2ZrCl2 (2.18 g, 5 mmol), butyllithium (6.25
mL, 10 mmol), and 2-bromophosphinine 1 (1.01 g, 5 mmol). After
checking the formation of complex 2c by 31P NMR, the mixture was
cooled to -78° and methyllithium (3.12 mL, 5 mmol) was added
dropwise. The solution was then warmed to room temperature. 31P
NMR showed the formation of complex 3c. Upon removal of the
solvents in vacuo, the brown oil obtained was dissolved in benzene
(10 mL), filtrated, and heated at 80 °C for 2 h. The solvent was then
removed in vacuo, and complex 4c was purified by extraction with
hexane (20 mL) and filtration under nitrogen. The resulting solution
was then dried in vacuo to yield an yellow slightly air-sensitive oil.
Yield: 1.58 g (65%). 2c: 31P NMR (THF) δ 224.65. 3c: 31P (THF)
δ 221.65. 4c: 31P NMR (CDCl3) δ 19.50; 1H NMR (CDCl3): δ 0.05-
0.50 (m, 36H, SiMe3), 2.50 (s, 6H, Me of C7H7P), 2.74 (AA′X′, 6H, ∑
J(H-P) ) 5.75, Me of C7H7P), 5.45 (m, 4H, CH of C5H4SiMe3), 5.70
(m, 4H, CH of C5H4SiMe3), 5.85 (m, 8H, CH of C5H4SiMe3), 8.3
Synthesis of Dimer (4a). To a solution of (C5H5)2ZrCl2 (7.30 g,
25 mmol) in THF (200 mL) was added dropwise n-butyllithium (31.25
mL, 50 mmol, solution 1.6 M in hexane) at -78 °C. The solution
was allowed to stir for 15 min at -78 °C, then some 20 drops of
(13) (a) Buchwald, S. L.; watson, B. T.; Lum, R. T.; Nugent, W. A. J.
Am. Chem. Soc. 1987, 109, 7137. (b) Buchwald, S. L.; Fang, Q. J. Org.
Chem. 1989, 54, 2793.

η2-Phosphabenzyne-Zirconocene Dimers
J. Am. Chem. Soc., Vol. 119, No. 40, 1997 9421
(AXX′, 2H, ΣJ(H-P) ) 22.75, H6,6′); 13C NMR (CDCl3): δ 0.50-
0.55 (m, SiMe3), 23.30 (d, J(C-P) ) 2.65, Me of C7H7P), 30.35 (s,
Me of C7H7P), 104.45 (s, CH of C5H4SiMe3), 108.65 (s, CH of C5H4-
SiMe3), 109.90 (s, Cq of C5H4SiMe3), 112.00 (s, CH of C5H4SiMe3),
113.5 (s, CH of C5H4SiMe3), 138.15 (pseudo t, AXX′, ∑ J(C-P) )
30.50, C4 or C5 of C7H7P), 142.80 (pseudo t, AXX′, ∑ J(C-P) ) 19.65,
C4 or C5 of C7H7P), 155.85 (pseudo t, AXX′, ∑ J(C-P) ) 39.80, C6
of C7H7P), 180.30 (pseudo t, AXX′, ∑ J(C-P) ) 87.80, C2 of C7H7P),
184.65 (pseudo t, AXX′, ∑ J(C-P) ) 48.55, C3 of C7H7P); mass
spectrum, m/z (relative intensity) 975 (M, 5), 489 (M/2 + 1, 30), 138
(C5H4SiMe3 + 1, 100). Complex 4c turned out to be too oxygen-
sensitive to give a satisfactory elemental analysis.
A first fraction, eluted with hexane, yielded some unreacted alkyne.
Phosphinine 8 was then eluted with a mixture of hexane/ether (9:1).
After removal of the solvent, 8 was isolated as a yellow slightly air-
sensitive oil. Yield: 1.43 g (70%). 7R: 31P NMR (THF) δ 200.45
(d, 4J(P-P) ) 12.70, dP-), -19.95 (d, PPh2). 7â: 31P NMR (THF)
4
δ 202.10 (d, J(P-P) ) 96.5, dP-), -8.25 (d, PPh2). 8: 31P NMR
(CDCl3) δ 185.95 (s, P of C7H8P), -2.14 (s, PPh2); 1H NMR (CDCl3)
δ 2.29 (d, 3H, J(H-P) ) 3.38, Me of C7H8P), 2.43 (s, 3H, Me of
4
2
C7H8P), 7.05 (t, 1H, J(H-P) ) J(H-P) ) 3.45, dCH-P), 7.20-
7.80 (m, 15H, 3 × C6H5), 8.47 (d, 1H, 2J(H-P) ) 38.5, H6); 13C (NMR
CDCl3) δ 23.10 (d, J(C-P) ) 2.50, Me of C7H8P), 23.80 (d, J(C-P)
) 3.3, Me of C7H8P), 128.00-130.00 (m, CH of C6H5), 132.50-133.0
1
(m, CH of C6H5), 134.55 (d, J(C-P) ) 18.00, dCH-P), 136.95 (d,
Synthesis of Complex 5. A solution of dimer 4b (0.74 g, 1 mmol)
and acetonitrile (41 mg, 1 mmol) in THF (10 mL) was heated at 70 °C
for 1 h. The solvent was removed in vacuo, and the brown oil obtained
was partially dissolved in toluene (15 mL) and filtrated under nitrogen.
The removal of the solvent yielded complex 5 as a brown water-
sensitive powder: yield 0.62 g (75%); 31P NMR (CDCl3) δ 212.85; 1H
NMR (CDCl3) δ 1.62 (s, 6H, Me of C5H4Me), 2.20 (d, 3H, J(H-P) )
3.20, Me of C7H7P), 2.37 (s, 3H, Me of C7H7P), 2.66 (d, 3H, 4J(H-P)
) 2.43, Me-Cd), 5.60-6.40 (m, 8H, CH of C5H4Me), 8.36 (d, 1H,
2J(H-P) ) 37.92, H6); 13C NMR (CDCl3) δ 14.70 (s, Me of C5H4Me),
25.90 (s, Me-Cd), 26.30 (d, J (C-P) ) 7.80, Me of C7H7P), 26.50
(s, Me of C7H7P), 104.25 (s, CH of C5H4Me), 105.45 (s, CH of C5H4-
Me), 118.75 (s, CH of C5H4Me), 123.35 (s, CH of C5H4Me), 128.95
(s, CH of C5H4Me), 142.40 (d, J(C-P) ) 12.35, CH of C7H7P), 148.40
3J(C-P) ) 6.35, Cq of C6H5), 137.40 (d, 2J(C-P) ) 12.35, C3), 139.45
(d, J(C-P) ) 15.6, C4 or C5 or Cq of C6H5), 140.90 (d, J(C-P) )
10.70, C4 or C5 or Cq), 143.70 (d, J(C-P) ) 15.20, C4 or C5 or Cq),
1
2
155.20 (d, J(C-P) ) 50.30, C6 of C7H8P), 159.60 (dd, J(C-P) )
25.55, 2J(C-P) ) 22.10, )C-Ph), 171.30 (dd, 1J(C-P) ) 53.60,
3J(C-P) ) 7.10, C2 of C7H8P); mass spectrum, m/z (ion, relative
intensity) 410 (M, 100), 225 (M - PPh2, 40). Anal. Calcd for
C27H24P2: C, 79.01; H, 5.89. Found: C, 79.55; H, 5.92.
Synthesis of Phosphinine 10 and Complex 11. A solution of
freshly prepared Zr(C5H5)2(Me)(C7H8P) complex 2a (5 mmol) in THF
(50 mL) was heated with (trimethylsilyl)acetylene (0.49 g, 10 mmol)
at 70 °C for 2 h. The mixture was cooled to room temperature, a sample
of solution (2 mL) was taken for the NMR characterizations of
intermediate 9, and then the solvent and the excess alkyne were
evaporated. The brown oil obtained was dissolved in a mixture of
methanol (20 mL) and dichloromethane (20 mL), and the resulting
mixture was treated with a 12 N HCl solution (20 drops) for 2 h at
room temperature. The transformation of complex metallacycle 9 into
phosphinine 10 was controlled by 31P NMR. The orange solution thus
obtained was washed three times with water (40 mL), dried with
MgSO4, and then filtrated under nitrogen. Celite (3 g) was added, and
the solvent was removed in vacuo. Phosphinine 10 was chromato-
graphed on silica gel using hexane as eluent. After removal of the
solvent, 11 was isolated as a yellow slightly air-sensitive oil. Yield:
0.83 g (75%). To obtain satisfactory microanalytical data, phosphinine
10 was complexed by W(CO)5THF using the following procedure.
Phosphinine (0.40 g, 1.80 mmol) in solution in THF (5 mL) was added
to a freshly prepared solution of W(CO)5THF (1.85 mmol). The
mixture was stirred for 30 min at room temperature. Celite (3 g) was
added, and the solvent removed in vacuo. The powder obtained was
chromatographed on silica gel. A first fraction, eluted with hexane,
yielded some traces of unreacted W(CO)6. Complex 11 was eluted
with a mixture of hexane/CH2Cl2 (9:1). After removal of the solvent,
11 was obtained as a yellow solid. Yield: 0.88 g (90%). 9: 31P NMR
1
(d, J(C-P) ) 19.90, Me of C7H7P), 152.20 (d, J(C-P) ) 39.25, C6
of C7H7P), 167.95 (d, 1J(C-P) ) 49.40, C2 of C7H7P), 191.45 (d, 2J(C-
2
P) ) 40.55, CdN), 209.65 (d, J(C-P) ) 18.30, C3 of C7H7P); mass
spectrum, m/z (ion, relative intensity) 413 (M, 15), 166 (M - (C5H4-
Me)2Zr, 80). Anal. Calcd for C21H24NPZr: C, 61.13; H, 5.86.
Found: C, 61.55; H, 5.90.
Synthesis of Phosphinine 6. A solution of dimer 4b (0.50 g, 0.81
mmol) and triphenylphosphine sulfide (0.47 g, 1.62 mmol) in THF (5
mL) was heated at 70 °C for 3 h. A yellow solid precipitated during
that time. A 31P NMR control showed the disparition of the signal
corresponding to the sulfide and the formation of free triphenylphos-
phine. Upon addition of ether (20 mL) the most part of the intermediary
metallacycle precipitated. The mixture was then filtrated under
nitrogen. The yellow powder that was collected was washed succes-
sively with ether (10 mL) and hexane (10 mL). THF (5 mL) was then
added and the mixture was treated with chlorotrimethylsilane (1 mL)
and ethanol (1 mL) for 5 min at room temperature. 31P NMR showed
the completion of the hydrolysis. After evaporation of the solvent,
hexane (30 mL) was added and the mixture was filtrated under nitrogen.
Celite (1 g) was added and hexane was removed in vacuo, yielding a
yellow powder which was deposited onto the top of a silica gel packed
flash column for chromatography. Phosphinine 6 was eluted purified
using hexane as eluent. Removal of hexane yielded 6 as a white
1
(CDCl3) δ 199.55; H NMR (CDCl3) δ 0.20 (s, 9H, SiMe3), 1.99 (s,
3H, J(H-P) ) 3.25, Me of C7H7P), 2.40 (s, 3H, Me of C7H7P), 6.30
1
powder: yield 0.33 g (70%); 31P NMR (CDCl3) δ 183.30; H NMR
3
(S, 10H, CH of C5H5), 7.64 (d, 1H, J(H-P) ) 8.85, dCH), 8.33 (d,
2
1H, J(H-P) ) 35.50, H6); 13C NMR (CDCl3) : δ 1.20 (s, SiMe3),
(CDCl3) δ 2.31 (d, 3H, J(H-P) ) 3.65, Me), 2.35 (s, 3H, Me), 4.04
(d, 1H, 3J(H-P) ) 8.91, SH), 7.63 (d, 1H, 3J(H-P) ) 4.77, H3), 8.26
24.40 (d, J(C-P) ) 3.95, Me of C7H7P), 25.30 (s, Me of C7H7P), 111.30
2
(d, 1H, J(H-P) ) 43.33, H6); 13C NMR (CDCl3) δ 22.95 (s, Me),
2
(s, C5H5), 136.85 (d, J(C-P) ) 49.10, dCH), 137.60 (d, J(C-P) )
23.45 (d, J(C-P) ) 4.35, Me), 136.90 (d, J(C-P) ) 12.25, C4 or C5),
14.05, C4 or C5 of C7H7P), 144.55 (d, J(C-P) ) 19.75, C5 or C4),
2
1
1
136.90 (d, J(C-P) ) 12.25, C3), 140.90 (d, J(C-P) ) 16.80, C5 or
153.45 (d, J(C-P) ) 44.20, C6), 163.40 (d, J(C-P) ) 50.40, C2),
189.35 (d,
1
1
3J(C-P) ) 13.55, dC-Si), 207.50 (d, J(C-P) ) 21.25,
2
C4), 156.20 (d, J(C-P) ) 52.05, C6), 158.20 (d, J(C-P) ) 59.30,
C2); mass spectrum, m/z (ion, relative intensity) 156 (M, 100). Anal.
Calcd for C7H9PS: C, 53.83; H, 5.81. Found: C, 54.56 ; H, 5.77.
C3). 10: 31P NMR (THF) δ 202.65; 1H NMR (CDCl3) δ 0.17 (s, 9H,
3
SiMe3), 2.34 (d, 3H, Me of C7H8P), 6.71 (dd, 1H, J(H-H) ) 18.90,
4J(H-P) ) 4.06, dCHSi), 7.12 (dd, 1H, J(H-H) ) 18.90, J(H-P)
) 10.35, dCH), 7.67 (d, 1H, 3J(H-P) ) 5.94, H3), 8.41 (d, 1H, 2J(H-
P) ) 8.38, H6); 13C NMR (CDCl3) δ -0.50 (s, SiMe3), 22.90 (s, Me
of C7H8P), 23.60 (d, J(C-P) ) 3.65, Me of C7H8P), 129.60 (d, 3J(C-
3
3
Synthesis of Phosphinine 8. To a freshly prepared solution of Zr-
(C5H5)2(Me)(C7H8P) complex 3a (5 mmol) in THF (50 mL) was added
phenethynyldiphenylphosphine (1.43 g, 5 mmol). The mixture was
then heated at 70 °C for 3 h. 31P NMR showed the transformation of
complex 3a into complexs 7R and 7â (95:5). The solvent was removed
in vacuo, and the brown oil obtained was dissolved in a mixture of
dichloromethane (20 mL) and methanol (20 mL). The solution was
then acidified at room temperature with 20 drops of a 12 N HCl solution
2
P) ) 20.65, dC-Si), 135.70 (d, J(C-P) ) 13.50, C3), 139.30 (d,
J(C-P) ) 16.90, C4 or C5), 142.85 (d, J(C-P) ) 16.05, C5 or C4),
147.00 (d, 2J(C-P) ) 39.20, dCH), 155.00 (d, 1J(C-P) ) 48.80, C6),
1
165.65 (d, J(C-P) ) 44.40, C2); mass spectrum, m/z (ion, relative
intensity) 222 (M, 30), 207 (M - 15, 100). 11: 31P NMR (CDCl3) δ
155.15 (1J(P-W) ) 257.20); 1H NMR (CDCl3) δ 0.19 (s, 9H, SiMe3),
2.37 (d, 3H, J(H-P) ) 6.12, Me of C7H8P), 2.41 (d, 3H, J(H-P) )
1.84, Me of C7H8P), 6.55 (dd, 1H, 3J(H-H) ) 18.80, 4J(H-P) ) 3.44,
and stirred for 2 h.
A
31P NMR control showed the unambiguous
formation of phosphinine 8. The orange solution thus obtained was
washed three times with water (40 mL), dried with MgSO4, and then
filtrated under nitrogen. Celite (3 g) was added and the solvent was
removed in vacuo. Phosphinine 8 was chromatographed on silica gel.
3
3
dCHSi), 7.21 (dd, 1H, J(H-H) ) 18.80, J(H-P) ) 12.80, dCH),

9422 J. Am. Chem. Soc., Vol. 119, No. 40, 1997
Rosa et al.
3
2
7.94 (d, 1H, J(H-P) ) 19.05, H3), 8.07 (d, 1H, J(H-P) ) 24.90,
H6); 13C NMR (CDCl3) δ -0.80 (s, SiMe3), 23.05 (d, J(C-P) ) 4.30,
Me of C7H8P), 23.90 (d, J(C-P) ) 9.60, Me of C7H8P), 132.25 (d,
J(C-P) ) 18.60, dC-SiMe3 or dCH), 135.65 (d, J(C-P) ) 12.10,
dCH or dC-SiMe3), 138.25 (d, J(C-P) ) 25.90, C4 or C5), 142.45
(d, 2J(C-P) ) 20.00, C3), 147.90 (d, J(C-P) ) 16.95, C4 or C5), 150.40
C5 of C7H8P), 143.80 (d, J(C-P) ) 15.50,C4 or C5 of C7H8P), 149.70
(d, 3J(C-P) ) 6.00, Cq of C4H3S), 154.5 (d, 1J(C-P) ) 49.00, C6 of
1
C7H8P), 172.45 (d, J(C-P) ) 47.15, C2 of C7H8P); mass spectrum,
m/z (ion, relative intensity) 236 (M, 90), 218 (M - H2O, 30); Anal.
Calcd for C12H13OPS: C, 61.00; H, 5.55. Found: C, 61.43; H, 5.56.
Synthesis of Phosphinine 17 and Complex 18. A solution of
freshly prepared Zr(C5H5)2(Me)(C7H8P) complex 3a (10 mmol) in THF
(10 mL) was heated with freshly dried (+)-camphor (1.21 g, 8 mmol)
at 80 °C for 60 h. The resulting mixture was cooled to room
temperature, and a sample of solution was taken for NMR characteriza-
tions of metallacycle 16 before evaporation of the solvent. The brown
oil obtained was dried under reduced pressure for 3 h to sublimate any
traces of unreacted camphor. The black solid obtained was then
dissolved in a mixture of dichloromethane (20 mL) and methanol (20
mL). The resulting solution was then acidified a 12 N HCl solution
1
1
(d, J(C-P) ) 21.70, C6), 158.50 (d, J(C-P) ) 21.40, C2), 195.25
(d, 2J(C-P) ) 9.25, CO cis), 199.60 (d, 2J(C-P) ) 29.00, CO trans);
mass spectrum, m/z (ion, relative intensity) 546 (M, 30), 490 (M -
2CO, 85), 390 (M - 4CO - MeH, 100). Anal. Calcd for C17H19O5-
PSiW: C, 37.38; H, 3.51. Found: C, 37.31; H, 3.68.
Synthesis of Phosphinine (14). Ferrocenecarboxaldehyde (1.50 g,
10 mmol) was added to a freshly prepared solution of Zr(C5H4Me)2-
(Me)(C7H8P) complex 4b (5 mmol) in THF (50 mL). The mixture
was then heated at 70 °C for 2 h. After this period, a 31P NMR control
showed the complete transformation of complex 4b into metallacycle
12. A sample of solution was taken for NMR characterizations of 12.
The solvent was then removed in vacuo, and the oil obtained was
dissolved in a mixture of dichloromethane (20 mL) and methanol (20
mL). The resulting solution was then acidified with a 12 N HCl solution
(20 drops) and stirred for 2 h. Formation of phosphinine 14 was
followed by 31P NMR. The organic solution was washed three times
with water (40 mL), dried with MgSO4, and then filtrated under
nitrogen. Celite (2 g) was added, and the solvent was removed in vacuo.
Phosphinine 14 was chromatographed on alumina using a mixture of
hexane/ether (5:1) as eluent. Removal of the solvent yielded 14 as a
deep red solid. Yield: 1.26 g (75%). 12: 31P NMR (CDCl3) δ 184.00;
1H NMR (CDCl3) δ 1.73 (d, 3H, J(H-P) ) 3.5, Me of C7H7P), 1.96
(s, 3H, Me of C5H4Me), 2.01 (s, 3H, Me of C5H4Me), 2.20 (s, 3H, Me
of C7H7P), 3.90-4.20 (m, 4H, CH of C5H4), 4.08 (s, 5H, CH of C5H5),
(20 drops) and stirred for 1 h.
A
31P NMR control indicated the
completion of the hydrolysis. The orange solution thus obtained was
washed three times with water (40 mL), dried with MgSO4, and then
filtrated under nitrogen. Alumina (3 g) was added, and the solvent
was removed in vacuo. Phosphinine 17 was chromatographed on
alumina using a mixture of hexane/ether (4:1) as eluent. After removal
of the solvent, 17 was isolated as an yellow-orange oil. Yield: 1.5 g
(55%). The complexation of 17 was conducted with W(CO)5THF as
follows. A solution of phosphinine 17 (0.55 g, 2 mmol) in THF (5
mL) was added to a freshly prepared solution of W(CO)5THF (2 mmol).
The mixture was stirred for 30 min at room temperature. Total
complexation was controlled by 31P NMR. Alumina (3 g) was added,
and the solvent removed in vacuo. The powder obtained was
chromatographed on silica gel. Complex 18 was eluted with a mixture
of hexane/ether (3:1) as eluent. After removal of the solvent, 18 was
obtained as a yellow powder. Yield: 0.84 g (70%). Crystals were
obtained by pentane diffusion into a dichloromethane solution of 18,
in a 5 mm NMR tube at room temperature. 16: 31P NMR (CDCl3) δ
196.05; 1H NMR (CDCl3) δ 0.80 (s, 9H, Me), 1.87 (d, 3H, J(H-P) )
5.68, Me of C7H7P), 2.22 (s, 3H, Me of C7H7P), 5.87-6.44 (m, 10H,
2
5.70-6.30 (m, 8H, CH of C5H4Me), 8.08 (d, 1H, J(H-P) ) 38.00,
H6); 13C NMR (CDCl3) δ 15.15 (s, Me of C5H4Me), 15.40 (s, Me of
C5H4Me), 24.20 (d, J(C-P) ) 2.80, Me of C7H7P), 26.35 (s, Me of
C7H7P), 69.10-70.00 (m, C10H9Fe), 89.25 (d, 2J(C-P) ) 39.90, CH-
O), 109.05, 109.25, 111.10, 111.90, 112.60, 114.50, 114.90, 115.80
(s, CH of C5H4Me), 127.30 (s, Cq of C5H4Me), 129.05 (s, Cq of C5H4-
Me), 137.20 (d, J(C-P) ) 14.85, C4 or C5), 144.20 (d, J(C-P) )
2
2 × C5H5), 8.14 (d, 1H, J(H-P) ) 39.42, H6 of C7H7P); 13C NMR
(CDCl3) δ 14.05 (s, C8′), 22.35 (s, C9′ or C10′), 22.65 (s, C10′ or C9′),
1
2
20.85, C4 or C5), 152.65 (d, J(C-P) ) 44.35, C6), 188.15 (d, J(C-
24.10 (s, Me of C7H7P), 24.20 (s, Me of C7H7P), 25.50 (s, C5′ or C6′),
P) ) 13.30, C3), 194.80 (d, 1J(C-P) ) 56.70, C2). 14: 31P NMR
3
32.25 (d, J(C-P) ) 36.45, C5′ or C6′), 46.60 (s, C4′), 52.20 (d, J(C-
1
P) ) 4.65, C1′), 54.15 (d, 3J(C-P) ) 8.45, C3′), 55.60 (s, C7′), 102.50
(CDCl3) δ 182.00; H NMR (CDCl3) δ 2.33 (d, 3H, Me of C7H8P),
2
2.38 (s, 3H, Me of C7H8P), 4.13 (m, 9H, CH of C10H9Fe), 5.66 (d, 1H,
3J(H-P) ) 8.94, CH), 7.67 (d, 1H, 3J(H-P) ) 6.00, H3), 8.40 (d, 1H,
2J(H-P) ) 38.82, H6); 13C NMR (CDCl3) δ 25.30 (s, Me of C7H8P),
(d, J(C-P) ) 25.85, C2′), 110.40-114.60 (m, CH of C5H5), 136.65
(d, J(C-P) ) 14.10, C4 or C5 of C7H7P), 142.80 (d, J(C-P) ) 20.60,
C5 or C4 of C7H7P), 152.10 (d, 1J(C-P) ) 44.85, C6 of C7H7P), 189.10
2
2
1
25.90 (s, Me of C7H8P), 66.30-70.00 (m, C10H9Fe), 74.55 (d, J(C-
(d, J(C-P) ) 13.75, C3 of C7H7P), 199.60 (d, J(C-P) ) 64.10, C2
of C7H7P); mass spectrum, m/z (ion, relative intensity) 494 (M, 1), 152
(camphor, 30), 66 (C5H5 + 1, 85). 17: 31P NMR (CDCl3) δ 186.62;
1H NMR (CDCl3) δ 0.92 (s, 3H, Me), 0.99 (s, 3H, Me), 1.28 (s, 3H,
Me), 1.30-1.80 (m, 4H, H5′ et H6′), 1.92 (ABMNX, 1H, 3J(H-Heq) )
4.40, H4′) 2.23 (ABMNX, 1H, 2Jgem ) 13.88, 3J(H-Heq) ) 4.40, 4J(H-
Heq) ) 3.05, 4J(H-P) ) 1.45, H3′eq), 2.39 (d, 3H, J(H-P) ) 3.65, Me
of C7H8P), 2.41 (d, 3H, J(H-P) ) 0.84, Me of C7H8P), 2.76 (ABMNX,
1H, 4J(H-P) ) 4.60, H3′ax), 7.94 (d, 1H, 3J(H-P) ) 5.62, H3 of C7H8P),
P) ) 35.15, C-O), 135.10 (d, 2J(C-P) ) 12.50, C3), 139.15 (d, J(C-
P) ) 17.0, C4 or C5), 142.85 (d, J(C-P) ) 16.15, C5 or C4), 154.20
(d, 1J(C-P) ) 48.60, C6), 172.05 (d, 1J(C-P) ) 45.95, C2); mass
spectrum, m/z (ion, relative intensity) 322 (M - 16, 100), 257 (322 -
C5H5, 100). Anal. Calcd for C18H19FeOP: C, 63.93; H, 5.66. Found:
C, 63.55; H, 5.86.
Synthesis of Phosphinine (15). A solution of dimer 4b (2.23 g,
3.00 mmol) and 2-thienecarboxaldehyde (0.70 g, 6.25 mmol) in THF
(30 mL) was heated at 80 °C for 3 h. After this period a 31P NMR
control indicated the formation of metallacycle 13. After removal of
the solvent, the oil obtained was dissolved in a mixture of dichlo-
romethane (30 mL) and methanol (30 mL). The solution was then
acidified with a 12 N HCl solution (20 drops), and stirred for 2 h. The
hydrolysis was monitored by 31P NMR. The resulting solution was
washed three times with water (40 mL), dried with MgSO4, and then
filtrated under nitrogen. Celite (3 g) was added, and the solvent was
removed in vacuo. Phosphinine 15 was chromatographed on alumina
using a mixture of hexane/ether (5:1) as eluent. Removal of the solvent
yielded 15 as an yellow oil. Yield: 1.00 g (70%). 13: 31P NMR
(THF) δ 189.15 (2J(P-H) ) 38.90). 15: 31P NMR (CDCl3) δ 183.30;
1H NMR (CDCl3) δ 2.59 (d, 3H, J(H-P) ) 4.02, Me of C7H8P), 2.66
(d, 3H, J(H-P) ) 1.45, Me of C7H8P), 6.49 (d, 1H, 3J(H-P) ) 8.50,
CH), 7.17-7.26 (m, 2H, H3′ and H4′ of C4H3S), 7.50 (m, 1H, H5′ of
2
8.39 (d, 1H, J(H-P) ) 39.83, H6 of C7H8P); 13C NMR (CDCl3) δ
10.65 (s, C8′), 22.30 (s, C9′ or C10′), 22.50 (s, C10′ or C9′), 23.45 (s, Me
of C7H8P), 23.50 (s, Me of C7H8P), 26.80 (s, C5′ or C6′), 32.20 (s, C5′
or C6′), 46.30 (s, C4′), 47.10 (d, 3J(C-P) ) 16.60, C3′), 51.25 (d, 3J(C-
P) ) 4.40, C1′), 54.15 (s, C7′), 86.15 (d, 2J(C-P) ) 18.30, C2′), 136.55
(d, 2J(C-P) ) 12.30, C3 of C7H8P), 138.95 (d, J(C-P) ) 16.75, C4 or
C5 of C7H8P), 142.20 (d, J(C-P) ) 15.25, C5 or C4 of C7H8P), 152.95
1
1
(d, J(C-P) ) 50.10, C6 of C7H8P), 176.40 (d, J(C-P) ) 50.65, C2
of C7H8P); mass spectrum, m/z (ion, relative intensity) 276 (M, 20),
258 (M - H2O, 3); 166 (M - C8H14, 100). 18: 31P NMR (CDCl3) δ
148.35 (1J(P-W) ) 128.10); H NMR(CDCl3) δ 0.84-1.43 (m, 4H,
1
H5′ et H6′), 0.96 (s, 3H, Me), 1.02 (s, 3H, Me), 1.27 (s, 3H, Me), 1.79-
1.92 (m, 1H, H3′eq), 1.99 (s, 1H, H3′ax), 2.08 (s, 1H, H4′), 2.34 (d, 3H,
J(H-P) ) 8.61, Me of C7H8P), 2.39 (s, 3H, Me of C7H8P), 7.69 (d,
3
2
1H, J(H-P) ) 19.05, H3 of C7H8P), 8.23 (d, 1H, J(H-P) ) 27.09,
H6 of C7H8P); 13C NMR (CDCl3) δ 12.00 (s, C8′), 22.25 (s, C9′ or C10′),
22.45 (s, C10′ or C9′), 23.40 (s, Me of C7H8P), 23.50 (s, Me of C7H8P),
27.45 (s, C5′ or C6′), 31.65 (s, C5′ or C6′), 46.15 (s, C4′), 49.55 (d, 3J(C-
3
2
C4H3S), 7.98 (d, 1H, J(H-P) ) 6.00, H3), 8.40 (d, 1H, J(H-P) )
54.30, H6); 13C NMR (CDCl3) δ 23.15 (s, Me of C7H8P), 23.85 (d,
J(C-P) ) 3.50, Me of C7H8P), 75.15 (d, 2J(C-P) ) 32.20, CH), 111.85
(s, CH of C4H3S), 126.05 (s, CH of C4H3S), 127.30 (s, CH of C4H3S),
2
P) ) 3.40, C3′), 51.70 (s, C1′), 55.30 (s, C7′), 88.30 (d, J(C-P) )
2
135.80 (d, J(C-P) ) 13.70, C3), 140.10 (d, J(C-P) ) 16.90, C4 or
6.90, C2′), 136.20 (d, 3J(C-P) ) 26.65, C4 or C5 of C7H8P), 139.00 (d,

η2-Phosphabenzyne-Zirconocene Dimers
J. Am. Chem. Soc., Vol. 119, No. 40, 1997 9423
Table 1. Crystal Data for Complexs 4b and 18
(d, 2J(C-P) ) 21.35, CO trans); mass spectrum, m/z (ion, relative
intensity) 600 (M, 1), 572 (M - CO, 10), 544 (M - 2CO, 10), 528
(M - 3CO, 10), 460 (M - 5CO, 55). Anal. Calcd for C22H25O6PW:
C, 44.02; H,4.20. Found: C, 44.02; H, 4.28.
4b
18
formula
space group
data collection temperature (K)
C38H42Zr2P2
P21/c (no. 14)
123
C22H24O6PW
P21 (no. 4)
123
10.966(2)
12.340(3)
16.639(4)
92.95(2)
2248.(1.)
4
X-ray Structure Determinations. All data sets were collected on
an Enraf Nonius CAD4 diffractometer using Mo KR radiation (λ )
0.710 73 Å) and a graphite monochromator. The crystal structures were
solved by direct methods using SIR92 and refined with the Enraf Nonius
MOLEN package using reflections having F2 < 3.0σ(F2). The
hydrogen atoms were included as fixed contributions in the final stages
of least-squares refinement for the tungsten complex. The zirconium
compound hydrogen atoms were refined with isotropic temperature
factors. Anisotropic temperature factors were used for all other atoms.
Crystal data are assembled in Table 1.
a (Å)
b (Å)
c (Å)
â (deg)
V (Å3)
Z
8.217(1)
18.037(5)
22.328(5)
97.79(2)
3278.(2.)
4
1.506
7.5
60.0
10041
7266
d
calcd (g/cm3)
1.770
µ (cm-1
)
53.5
60.0
7141
5988
maximum 2θ
no. of reflns measd
no. of reflns included
no. of params refined
unweighted agreement factor:
weighted agreement factor:
GOF
Acknowledgment. We thank CNRS and Ecole Polytech-
nique for supporting this work.
547
0.024
0.038
1.01
541
0.023
0.030
1.04
0.00
Supporting Information Available: X-ray structure deer-
mination for 4b and 18, positional parameters, bond distances,
angles and âij values (22 pages). See any current masthead page
for ordering and Internet access instructions.
convergence, largest shift/error
0.01
2J(C-P) ) 12.50, C3 of C7H8P), 145.95 (d, J(C-P) ) 16.90, C5 or C4
of C7H8P), 155.45 (d, 1J(C-P) ) 16.65, C6 of C7H8P), 168.55 (d, 1J(C-
P) ) 13.35, C2 of C7H8P), 197.35 (d, 2J(C-P) ) 9.05, CO cis), 200.70
JA971679I