Synthesis and reactivity of phosphirane ligands and the structural characterization of Cp*IrCl2(tert-butylphosphirane)

Article abstract of DOI:10.1021/om960400o

New and stable phosphiranes, tert-butylphosphirane and xylylphosphirane, were prepared. tert-Butylphosphirane is stable to polymerization in the presence of electrophiles. It was reacted with bis((μ-chloro)chloro(pentamethylcyclopentadienyl)iridium) to pr

Full text of DOI:10.1021/om960400o

1526
Organometallics 1997, 16, 1526-1530
Articles
Syn th esis a n d Rea ctivity of P h osp h ir a n e Liga n d s a n d
th e Str u ctu r a l Ch a r a cter iza tion of
Cp *Ir Cl2(ter t-bu tylp h osp h ir a n e)
Nicolas Me´zailles, Phillip E. Fanwick,† and Clifford P. Kubiak*
Department of Chemistry, 1393 Brown Laboratory, Purdue University,
West Lafayette, Indiana 47907-1393
Received May 23, 1996X
New and stable phosphiranes, tert-butylphosphirane and xylylphosphirane, were prepared.
tert-Butylphosphirane is stable to polymerization in the presence of electrophiles. It was
reacted with bis((µ-chloro)chloro(pentamethylcyclopentadienyl)iridium) to prepare (tert-
butylphosphirane)dichloro(pentamethylcyclopentadienyl)iridium, which was characterized
by X-ray diffraction. tert-Butylphosphirane was also reacted with pentacarbonyl(tetrahy-
drofuran)tungsten and borane to form (tert-butylphosphirane)pentacarbonyltungsten and
the first phosphirane-borane adduct, respectively.
Phosphiranes are three-membered phosphorus het-
The syntheses of phenylphosphirane (1), tert-butylphos-
phirane (2), and xylylphosphirane (3) are described.
Phosphiranes 2 and 3 are found to be quite stable, and
the reactivity of 2 and its use as a ligand are reported
together with the X-ray crystal and molecular structure
of Cp*IrCl2(tert-butylphosphirane) (4) (Cp* ) C5(CH3)5).
erocycles, first reported by Wagner et al. in 1967.1 Chan
et al. reported that unsubstituted phosphiranes were
unstable toward polymerization or decomposition.2 Be-
cause of their intrinsic instability, phosphiranes were
not studied in detail until Mathey et al. developed a
method to synthesize phosphiranes in the coordination
sphere of group 6 transition metal complexes.3-5 This
approach provides an understanding of the structure of
these heterocycles, but it does not give insight into their
reactivity. Attempts have been made to synthesize
stable free phosphiranes. The stability of these highly
strained systems depends on two factors: the steric and
electronic properties of the substituent at the phospho-
rus atom and the degree of substitution of the ring. For
example, in 1991, Le Floch and Mathey were able to
synthesize 1-chlorophosphirane. This compound, stable
in solution, forms an insoluble and pyrophoric white
powder when concentrated.6 Baudler et al. prepared
2-methyl-1-tert-butylphosphirane, but in low (14%) yield
and as a mixture of diastereomers.7 By placing bulky
groups on the phosphorus atom, (2,4,6-trimethylphenyl)-
phosphirane and (2,4,6-tri-tert-butylphenyl)phosphirane
were prepared.8,9 We now describe an improved syn-
thesis of phosphiranes together with preliminary studies
of their unusual properties as phosphine donor ligands.
Resu lts a n d Discu ssion
The synthesis developed in our laboratories provides
a general method to alkyl- and arylphosphiranes (eq 1).
The method is analogous to the one reported recently
by Wild et al.10 The most general version of our
phosphirane synthesis is as follows. Treatment of a
large excess of phosphorus trichloride at 0 °C with a
Grignard reagent yields a mixture of dichloro- and
monochloroalkyl(or aryl)phosphines. After the removal
of excess PCl3, the mixture is reduced with LiAlH4 to
the corresponding phosphines. The resulting primary
and secondary phosphines are separated by distillation.
Two equivalents of methyllithium are added to the
desired primary phosphine. Then, 1 equiv of 1,2-
dichloroethane is added. The resulting phosphirane can
be purified by distillation. This synthesis is versatile.
It allows one to start with either PCl3, RPCl2, or RPH2,
depending on their commercial availability. Starting
from commercially available phenylphosphine, phenyl-
† Address correspondence pertaining to crystallographic studies to
this author.
X Abstract published in Advance ACS Abstracts, March 15, 1997.
(1) Wagner, R. I.; Freeman, L. D.; Goldwhite, H.; Rowsell, D. G. J .
Am. Chem. Soc. 1967, 89, 1102.
(2) Chan, S.; Goldwhite, H.; Keyzer, H.; Rowsell, D. G.; Tang, R.
Tetrahedron 1969, 25, 1097.
(3) Marinetti, A.; Mathey, F.; Fischer, J .; Mitschler, J . J . Chem. Soc.,
Chem. Commun. 1982, 667.
(4) Marinetti, A.; Mathey, F. Organometallics 1982, 1, 1488.
(5) Marinetti, A.; Mathey, F. Organometallics 1984, 3, 456.
(6) Le Floch, P.; Mathey, F. Synlett 1991, 743.
(7) Baudler, M.; Germeshlausen, J . Chem. Ber. 1985, 118, 4285.
(8) Oshikawa, T.; Yamashita, M. Synthesis 1985, 290.
(9) Yoshfuji, M.; Toyota, K.; Imamoto, N. Chem. Lett. 1985, 441.
S0276-7333(96)00400-1 CCC: $14.00 © 1997 American Chemical Society

Synthesis and Reactivity of Phosphirane Ligands
Organometallics, Vol. 16, No. 8, 1997 1527
Ta ble 1. Su m m a r y of Cr ysta llogr a p h ic Da ta for 4
formula
fw
IrCl2PC16H28
514.48
cryst size, mm
cryst syst
space group
a, Å
b, Å
c, Å
0.45 × 0.42 × 0.25
monoclinic
P21/n (No. 14)
15.909(2)
7.6358(9)
17.259(2)
115.309(9)
1895.4(8)
4
1.803
73.77
Mo KR (0.710 73 Å)
4287
â, deg
V, Å3
Z
D
calcd, g cm-3
µ, cm-1
Figu r e 1. ORTEP view of Cp*IrCl2(tert-butylphosphirane),
4.
radiation (λ, Å)
no. reflns measured
no. reflns used
no. variables
Ra
4150
197
0.027
0.033
phosphirane (1) is produced in 65% yield as a colorless
liquid. As reported earlier, this compound readily
decomposes2 to form a polymeric material. Because of
its lower boiling point, tert-butylphosphirane (2) is
typically codistilled with THF and used in this form
after NMR titration. Phosphirane 2 can also be isolated
as a pure colorless liquid. The neat liquid is stable at
-20 °C under nitrogen for several weeks, after which
time the 31P{1H} NMR spectrum shows some decompo-
sition products, but even after 2 months, 30% of the
starting material is still present. Xylylphosphirane (3)
is obtained in 30% yield starting from xylylmagnesium
bromide and PCl3. Phosphirane 3 is stable as a neat
liquid at -20 °C for extended periods of time. The
31P{1H} NMR signals of phosphiranes 1-3 occur at very
high field (δ ) -206 to -239 ppm), but still downfield
of the parent phosphirane PC2H5 (δ ) -341 ppm).1 The
31P{1H} NMR resonance for tert-butylphosphirane (2)
occurs considerably downfield of the arylphosphiranes
1 and 3.
b
Rw
a
b
2
1/2
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) (∑w(|Fo| - |Fc|)2/∑wFo
) .
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 4
Bond Distances
Ir-Cl(1)
Ir-Cl(2)
Ir-P(1)
Ir-C(11)
Ir-C(12)
Ir-C(13)
Ir-C(14)
2.415(2)
2.408(2)
2.296(1)
2.152(6)
2.159(6)
2.229(6)
2.221(6)
Ir-C(15)
2.165(6)
1.808(8)
1.799(8)
1.873(6)
1.51(1)
1.53(1)
1.51(1)
1.535(9)
P(1)-C(2)
P(1)-C(3)
P(1)-C(4)
C(2)-C(3)
C(4)-C(5)
C(4)-C(6)
C(4)-C(7)
Bond Angles
88.96(7)
Cl(1)-Ir-Cl(2)
Cl(1)-Ir-P(1)
Cl(2)-Ir-P(1)
Ir-P(1)-C(2)
Ir-P(1)-C(3)
Ir-P(1)-C(4)
C(2)-P(1)-C(3)
C(2)-P(1)-C(4)
C(3)-P(1)-C(4)
P(1)-C(2)-C(3)
P(1)-C(3)-C(2)
P(1)-C(4)-C(5)
P(1)-C(4)-C(6)
P(1)-C(4)-C(7)
C(5)-C(4)-C(6)
C(5)-C(4)-C(7)
106.8(3)
65.0(4)
65.6(4)
107.9(4)
108.3(4)
112.8(5)
109.3(6)
108.8(6)
88.44(5)
90.83(5)
119.4(3)
122.6(3)
125.1(2)
49.5(4)
Phosphirane 2 was also characterized by its reaction
with [Cp*IrCl2]2 to afford Cp*IrCl2(tert-butylphos-
phirane) (4, eq 2). The 13C{1H} NMR spectrum of 4
110.1(4)
for C(sp3)-C(sp3) bonds (1.51(1) Å) and is in fact similar
to those found in the tert-butyl group. The C-C-P
angles, 65.0(4)° and 65.6(4)°, together with the C-P-C
angle of 49.5(4)° attest to the high degree of strain in
the phosphirane ring and the unusual chemical bonding
required in such a structure.11,12
In order to better understand the properties of the
new, stable phosphiranes prepared here, a systematic
comparison to other phosphiranes is warranted. There
is now a large body of physical data on (CO)5W-
(phosphirane) complexes prepared by Mathey’s method3
(eq 3). In order to compare the properties of our new
shows a doublet, 3J (P-C) ) 4 Hz, for the five equivalent
methyl groups of the Cp* ring, indicating the presence
of a phosphine ligand. Complex 4 was also character-
ized by a single-crystal diffraction study. The ORTEP
of complex 4 is shown Figure 1, and data collection and
refinement parameters are found in Table 1. Selected
bond distances and angles are given in Table 2. Com-
plex 4 possesses the expected “piano stool” structure.
The Ir-Cl and the Ir-Cp* distances are normal. The
Ir-P distance of 2.296(1) Å falls near the average length
for Cp*IrCl2(PR3) complexes. This is an apparent
consequence of the low steric demand of the piano stool
structure, which allows the phosphirane tert-butyl group
to rotate away from the Cp* ring, enabling the phos-
phorus atom to more closely approach the Ir center. This
is clearly seen in the ORTEP drawing of the complex,
Figure 1. The P-C bond distances within the phos-
phirane ring, 1.808(8) and 1.799(8) Å, are shorter than
the P-C bond distance to the tert-butyl group, 1.873(6)
Å. The phosphirane ring C-C distance is in the range
phosphiranes, we synthesized analogous tungsten-
phosphirane complexes according to eq 4. The reactions
are quantitative by IR, and isolated yields are in the
(10) Hockless, D. C. R.; Kang, Y. B.; McDonald, M. A.; Pabel, M.;
Willis, A. C.; Wild, B. S. Organometallics 1996, 15, 1301.
(11) Bachrach, S. H. J . Phys. Chem. 1989, 93, 7780.

1528 Organometallics, Vol. 16, No. 8, 1997
Me´zailles et al.
Ta ble 3. Com p a r ison of 31P {1H} NMR a n d IR Da ta
for (CO)5W(P (R)CH2CH2) Com p lexes
31P{1H}
NMR, ppm J (P-W),
R
(CD2Cl2)
Hz
IR ν(CO), cm-1 (THF)
ref
xylyl (6)
-202
c
2073(m), 1945(vs),
1920(sh)
14
15
Ph
-187.6a
258
244
tert-butyl (5) -163.5
2073(m), 1944(vs),
1914(m)
this work
range of 80-90%. A comparison of the spectroscopic
data for previously reported (CO)5W(phosphirane) com-
plexes and 5 and 6 appear in Table 3. The ν(CO) region
of the IR spectrum for these complexes is not signifi-
cantly affected by the different substituents on the
phosphirane phosphorus atom. In fact, no significant
difference is apparent in the ν(CO) bands of the alkyl-
phosphirane 5 compared to the arylphosphirane 6. This
suggests that phosphiranes are intrisically weak σ-donor
ligands. The 1J (P-W) coupling constant is usually
taken as a measure of the relative σ-donor ability within
NHPh
NEt2
Cl
-132
-111b
-98
288
278
303
303
15
2070(m), 1940(vs)d 16
15
15
OEt
-46
a
b
d
C6D6. CDCl3. c Not resolved. Decalin.
1J (P-W), thus, increase with the electron-acceptor
ability of the substituents at the phosphirane phospho-
rus atom as the σ-orbital overlap between tungsten and
phosphorus improves with bond distance contraction.
The unusual ligand donor/acceptor character of phos-
phiranes evident in their 31P{1H} NMR spectra was the
basis for further study of their reactivity. In sharp
contrast to previous reports concerning phenylphos-
phirane (1), tert-butylphosphirane (2) is remarkably
robust. Mathey19 has reported that phosphiranes are
readily polymerized by electrophiles. However, treat-
ment of 2 with triethyloxonium tetrafluoroborate does
not result in any noticable reaction. Reaction of 2 with
BH3‚THF resulted in the quantitative formation of the
first phosphirane-borane adduct, 7 (eq 5). Phosphirane-
1
a series of compounds.13 Indeed, J (P-W) is directly
related to the s character of the P-W bond, which can
be related to the s character of the lone pair of the
ligand. It appears likely that σ and π effects contribute
1
in different ways to the magnitude of J (P-W) in the
(CO)5W(phosphirane) complexes. Table 3 summarizes
the 1J (P-W) values for (CO)5WP(R)CH2CH2 (R ) xylyl,
Ph, t-Bu, NHPh, NEt2, Cl, OEt) complexes.
Phosphiranes with electron withdrawing substituents
(e.g., Cl or OEt) have significantly higher coupling
constants (1J (P-W) ) 303 Hz) compared to the phos-
phiranes with electron-donating substituents, such as
tert-butyl (1J (P-W) ) 244 Hz). This trend runs opposite
to that expected for simple σ inductive effects. It is
1
known that, in general, the magnitude of J (P-W) in
W(CO)5(PL3) depends linearly on the electronegativity
of the atom R to phosphorus.13 Therefore, it appears
that the W-P s-orbital overlap as well as the P lone pair
s character are important. The phosphiranes with
electron-withdrawing groups are stronger π-acceptor
ligands. These will then have shorter W-P bond dis-
tances due to W(dπ)-P(σ*) back-bonding and, for that
reason, greater s-orbital overlap. For example, the
(CO)5WP(R)CH2CH2 complex with R ) Cl was found to
have a relatively short W-P bond distance of 2.455(2) Å
borane 7 was characterized by 31P{1H} NMR, which
indicates a J (31P-11B) coupling constant of 30 Hz. In
this reaction, the phosphirane acts similarly to phos-
phines in forming borane adducts. However, unlike
phosphines, which require the presence of an excess
amount of a nucleophilic amine to be decomplexed,20-22
gently heating complex 7 reforms 2. No reaction is
observed between 2 and BF3‚Et2O, which is a somewhat
weaker Lewis acid than BH3. This reinforces our view
that 2 is an exceedingly weak σ-donor. Reaction of 2
with 9-BBN also did not produce the phosphirane-
borane adduct, likely for steric reasons. Phosphiranes
are also reported to be susceptible to nucleophilic ring
opening.19 However, neither 2 nor 1 react with a strong
nucleophiles, such as methyllithium.
In summary, a rational, apparently general synthesis
of phosphiranes is reported. This provides the op-
portunity for substantial further development of the
chemistry of these ligands with transition metals. To
illustrate the possibilities, we have synthesized phos-
phirane complexes (CO)5WP(R)CH2CH2 (R ) t-Bu (5),
xylyl (6)) to compare their spectroscopic properties to
the known complexes (R ) Ph, NHPh, NEt2, Cl, OEt).
We have shown that these ligands are weak σ-donors
1
and high J (P-W) ) 303 Hz, while the complex with R
) Ph was found to have a relatively long W-P bond
1
distance of 2.504(2) Å and low J (P-W) ) 258 Hz. The
complex with R ) piperidine shows both an intermedi-
ate W-P bond distance and an intermediate value of
1J (P-W) relative to the chloro- and aryl-subsituted
systems. These data suggest that phosphiranes possess
a high degree of s-character in their nonbonded electron
pairs,17,18 which contribute to weak σ-donating proper-
ties. Electron-withdrawing substituents at the phos-
phorus atom increase the phosphirane π-acceptor abil-
ity, decreasing W-P bond distances. Coupling constants
(12) Rauk, A.; Andose, J . D.; Frick, W. G.; Tang, R.; Mislow, K. J .
Am. Chem. Soc. 1971, 93, 6507.
(13) Verkade, J . G.; Mosko, J . A. In Phosphorus-31 NMR Spectro-
scopy in Stereochemical Analysis; Verkade, J . G., Quin, L. D., Eds.;
VCH: New York, 1987; pp 425-463.
(14) Hung, J .-T.; Yang, S.-W.; Gray, G. M.; Lammertsma, K. J . Org.
Chem. 1993, 58, 6786.
(15) Deschamps, B.; Ricard, L.; Mathey, F. Polyhedron 1989, 8, 2671.
(16) Mercier, F.; Deschamps, B.; Mathey, F. J . Am. Chem. Soc. 1989,
111, 9098.
(17) Aue, D. H.; Webb, H. M.; Davidson, W. R.; Vidal, M.; Bowers,
M. T.; Goldwhite, H.; Vertal, L. E.; Douglas, J . E.; Kollman, P. A.;
Kenyon G. L. J . Am. Chem. Soc. 1980, 102, 5151.
(18) Dobbs, K.; Boggs, J . E.; Barron, A. R.; Cowley, A. H. J . Phys
Chem. 1988, 92, 4886.
(19) Mathey, F. Chem. Rev. 1990, 90, 997.
(20) Imamoto, T.; Tusumoto, T.; Suzuki, N.; Sato, K. J . Am. Chem.
Soc. 1985, 107, 5301.
(21) Imamoto, T.; Oshiki, T.; Onozawa, T.; Kusumoto, T.; Sato, K.
J . Am. Chem. Soc. 1990, 112, 5244.

Synthesis and Reactivity of Phosphirane Ligands
Organometallics, Vol. 16, No. 8, 1997 1529
reveal any measurable decomposition over several weeks.
Yield: 90%. 31P{1H} NMR: δ -206. 1H NMR: δ 0.45 (m, 2H),
0.6 (m, 2H), 0.72 (d, C(CH3)3, 3J (H-P) ) 12 Hz). 13C{1H}
NMR: δ 2.7 (d, CH2, 1J (C-P) ) 43.3 Hz), 24.6 (d, C(CH3)3,
because of the high s-character of the phosphorus atom
lone pair. We also find that π-acceptor properties, which
increase with the electronegativity of the subsitutent
at phosphorus, are important in the binding of phos-
phiranes to transition metal complexes. Our studies
suggest that the often reported instability of phos-
phiranes can be avoided by increasing the bulk of the
substituents at the phosphorus atom.
3
1J (C-P) ) 32.3 Hz), 28.7 (d, C(CH3)3, J (C-P) ) 16.1 Hz). EI
MS (m/ e): 116.
Syn th esis of (2,6-Dim eth ylp h en yl)p h osp h ir a n e (xylyl-
p h osp h ir a n e, 3). The Grignard of 1-bromo-2,6-dimethylben-
zene is obtained in 95% yield following a reported procedure.24
C6H3(CH3)2MgBr is added dropwise at 0 °C to a stirred solution
of 3 equiv of trichlorophosphine in diethyl ether over the course
of several hours. The reaction yields a mixture of dichloro-
xylylphosphine (Cl2P(xylyl)) and chlorodixylylphosphine (ClP-
(xylyl)2). The ratio of the two compounds depends on the
addition rate. Phosphorus trichloride is removed, along with
THF, via vacuum distillation. The remaining residue is
transferred to a drybox, where magnesium salts are filtered
and washed with diethyl ether. The corresponding phos-
phines, xylylphosphine (H2P(xylyl)) and dixylylphosphine (HP-
(xylyl)2) are then prepared by the addition of an excess amount
of LiAlH4, using a method similar to the formation of tert-
butylphosphirane (2). After hydrolysis and ether extraction,
the organic layer is dried with magnesium sulfate, and the
phosphines are separated by vacuum distillation. Two equiva-
lents of methyllithium are added dropwise at -78 °C to a THF
solution of xylylphosphine. After 30 min, 1 equiv of 1,2-
dichloroethane is syringed in the reaction mixture. The
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were carried out
under nitrogen using standard Schlenk line and drybox
techniques. Solvents were degassed and purified by distilla-
tion under nitrogen from the appropriate drying agents
(sodium/benzophenone for THF, CaH2 for CH2Cl2). Methyl-
lithium (1.4 M in diethyl ether), 2-bromo-m-xylene,1, 2-dichlo-
roethane, and tungsten hexacarbonyl were purchased from
Aldrich Chemical Co. Tungsten hexacarbonyl was purified by
sublimation under vacuum prior to use. Anhydrous diethyl
ether was purchased from Mallinckrodt. The phosphines tert-
butyldichlorophosphine, phosphorus trichloride, and phenyl-
phosphine were purchased from Strem Chemical, Inc.
23
Cp*2Cl2(µ-Cl)2Ir2 was prepared according to published pro-
cedures. 1H and 13C{1H} NMR spectra were recorded on a
General Electric QE-300 spectrometer at 300.6 and 75.2 MHz,
respectively, with chemical shifts reported in ppm referenced
to internal SiMe4. 31P{1H} NMR spectra were recorded on a
QE-300 spectrometer at 121.4 MHz, with chemical shifts
reported in ppm referenced to external H3PO4. Infrared
spectra were recorded on a Perkin-Elmer 1710 FTIR spectro-
photometer.
solution is allowed to warm back to room temperature.
A
water/ether extraction is performed, and the etheral phase is
dried over magnesium sulfate. After filtration, xylylphos-
phirane is distilled under vacuum to yield a colorless oil.
Yield: 30%. 31P{1H} NMR: δ -239. 1H NMR: δ 0.9 (m, 2H),
1.05 (m, 2H), 2.4 (s, 6H, (CH3)2) 6.8 (m, 3H). 13C{1H} NMR:
1
2
δ 12.4 (d, CH2, J (C-P) ) 39.8 Hz), 22.6 (d, C(CH3)2, J (C-P)
Syn t h esis of P h en ylp h osp h ir a n e (1). Phenylphos-
phirane was prepared by a modification of the literature
procedure.2 Phenylphosphine (2.75 mL, 25 mmol) in THF is
cooled to -78 °C using a dry ice/isopropyl alcohol bath. Two
equivalents of methyllithium (50 mmol) is added dropwise, and
after complete addition, the mixture is stirred for 1 h.
Degassed 1,2-dichloroethane (2.48 g, 25 mmol) is added slowly
via syringe. The mixture is allowed to warm slowly to room
temperature (ca. 12 h). The cream-colored suspension is then
hydrolyzed with degassed water, and diethyl ether is added.
The organic layer is separated and dried over magnesium
sulfate. After filtration, the etheral layer is distilled under
vacuum. Phosphirane 1 distills at 90 °C (3.5 mmHg) to yield
a colorless oil. Yield: 65%. 31P{1H} NMR: δ -236. 1H
NMR: δ 0.9 (d, 2H), 0.95 (s, 2H), 7.0 (m, 5H). 13C{1H} NMR:
) 8.9 Hz), 127.9 (s), 127.9 (d, 3J (C-P) ) 2.7 Hz), 139.9 (d,
1J (C-P) ) 41.7 Hz), 142.3 (d, J (C-P) ) 9.4 Hz). EI MS (m/
2
e): 164. Anal. Calcd for C10H13P: C, 73.16; H, 7.98. Found:
C, 73.40; H, 8.09.
Syn th esis of (ter t-Bu tylp h osp h ir a n e)d ich lor o(p en ta -
m eth ylcyclop en ta d ien yl)ir id iu m (4). Three equivalents of
tert-butylphosphirane (2) (per equivalent of iridium) are
syringed into a CH2Cl2 solution of [Cp*IrCl2]2 (Cp*dC5(CH3)3)
at -78 °C. Upon warming, the solution mixture turns from
orange to yellow in color. The reaction is then stirred at room
temperature overnight. The solution volume is reduced, and
hexane is added. An orange solid precipitates and is removed
by filtration. Yield: 95%. 31P{1H} (CD2Cl2): δ -143.2. 1H
3
NMR (CD2Cl2): δ 1.2 (d, C(CH3)3, J (H-P) ) 17.25 Hz), 1.45
(m, 4H), 1.65 (d, 15H, 4J (H-P) ) 3.0 Hz). 13C{1H} NMR
1
3
δ 10.1 (d, CH2, J (C-P) ) 42.3 Hz), 127.9 (s), 127.9 (d, J (C-
1
2
1
(CD2Cl2): δ 4.1 (d, CH2, J (C-P) ) 8.9 Hz), 8.7 (s, C5(CH3)5),
P) ) 2.7 Hz), 132.3 (d, J (C-P) ) 9.4Hz), 139.9 (d, J (C-P) )
1
3
28.7 (d, C(CH3)3, J (C-P) ) 39.2 Hz), 29.0 (d, C(CH3)3, J (C-
P) ) 4.0 Hz), 92.2 (s, C5(CH3)5). PDMS (M + H): 515. Anal.
Calcd for C16H28PIrCl2: C, 37.35; H, 5.49. Found: C, 37.00;
H, 5.73.
41.7Hz).
Syn th esis of ter t-Bu tylp h osp h ir a n e (2). A THF solution
of LiAlH4 (3.14 mmol) is added dropwise to a THF solution of
dichloro-tert-butylphosphine (2.00 g, 12.6 mmol) at 0 °C. After
addition, the solution is stirred at 45 °C for 2 h. The resulting
tert-butylphosphine is distilled at 55 °C under atmospheric
pressure. To a THF solution of the distilled phosphine, 2 equiv
of methyllithium (25.2 mmol) is added dropwise at -78 °C.
After 30 min of stirring, 1 equiv of 1,2-dichloroethane (1.25 g,
12.6 mmol) is added. The solution is allowed to warm back to
room temperature. A water/ether extraction is performed, and
the etheral phase is dried over magnesium sulfate. After
filtration, the ether and a small amount of THF are removed
by atmospheric distillation. The phosphirane 2 is codistilled
with THF, using a bulb to bulb distillation apparatus. The
concentration of 2 in the THF solution is determined by 1H
NMR. The phosphirane 2 can be kept in THF solution at -20
°C indefinitely. As a neat colorless liquid, obtained by
Syn th esis of (ter t-Bu tylp h osp h ir a n e)p en ta ca r bon yl-
tu n gsten (5). A Schlenk flask is charged with tungsten
hexacarbonyl (100 mg, 0.28 mmol) dissolved in 100 mL of THF.
The solution is purged with nitrogen during a 1 h photolysis
(λ ) 330 nm, 1000 W). The formation of W(CO)5‚(THF) is
followed by IR spectroscopy. t-Butylphosphirane (0.28 mmol)
is added (in a mixture of Et2O and THF) to the deep yellow
solution of W(CO)5‚THF. The reaction is then stirred at room
temperature overnight. The THF is removed in vacuo, and
the residue is taken up with hexanes. The solution is filtered,
and the yellow-orange filtrate is cooled to -20 °C. Yellow
crystals of (tert-butylphosphirane)pentacarbonyltungsten were
collected by filtration. Yield: 90%. 31P{1H} (CD2Cl2): δ -163
1
atmospheric distillation of THF, 31P{1H} and H NMR do not
(23) Ball, R. G.; Graham, W. A. G.; Heinekey, D. M.; Hoyano, J . K.;
McMaster, A. D.; Mattson, B. M.; Michel, S. T. Inorg. Chem. 1990, 29,
2023.
(22) Bo¨rner, A.; Ward, J .; Ruth, W.; Holz, J .; Kless, A.; Heller, D.;
(24) Organic Syntheses; Wiley: New York, 1943; Collect. Vol. II, p
Kagan, H. B. Tetrahedron 1994, 50, 10419.
360.

1530 Organometallics, Vol. 16, No. 8, 1997
Me´zailles et al.
ppm (1J (W-P) ) 244 Hz). 1H NMR (CD2Cl2): δ 1.25 (d,
Attempts to remove the solvent under vacuum at low temper-
atures led only to the quantitative reformation of 2. 31P{1H}
(CD2Cl2): δ -114.5 ppm (1J (P-B) ) 30.0 Hz).
3
C(CH3)3, J (H-P) ) Hz), 1.35 (m, 2H), 1.60 (m, 2H). 13C{1H}
NMR (CD2Cl2): δ 6.0 (t, CH2, 1J (C-W) ) 8.0 Hz), 29.1 (s,
C(CH3)3), 31.2 (s, C(CH3)3). IR (THF) νCO (cm-1)): 2073 (m),
1944 (vs), 1914 (m). Anal. Calcd for C11H13PWO5: C, 30.02;
H, 2.98. Found: C, 29.78; H, 3.11.
Ack n ow led gm en t is made to the NSF (Grant CHE-
9319173) for support of this work. We are also grateful
to the NSF for support of the Chemical X-ray Diffraction
Facility at Purdue. We are grateful to Dr. G. Silverman
for many helpful suggestions regarding this work. N.M.
also thanks ELF AQUITAINE for fellowship support.
Syn th esis of (Xylylph osph ir an e)pen tacar bon yltu n gsten
(6). Prepared according to the same procedure as above.
Yield: 90%. 31P{1H} (CD2Cl2): δ -202. IR (THF) νCO (cm-1)):
Su p p or tin g In for m a tion Ava ila ble: Description of ex-
perimental procedures and tables of crystal data and collection
parameters, positional parameters, general temperature fac-
tors, bond distances, bond angles, and torsion angles for
complex 4 (21 pages). Ordering information is given on any
current masthead page.
2073 (m), 1945 (vs), 1914 (sh). Anal. Calcd for C15H13
PWO5: C, 36.91; H, 2.68. Found: C, 36.76; H, 2.86.
-
Syn t h esis of t h e ter t-Bu t ylm et h ylp h osp h ir a n e-
Bor a n e Ad d u ct (7). To a solution of 2 in THF is added 1.5
equiv of a solution of borane-THF (1 M). The reaction is
followed by 31P NMR, and after 12 h, the reaction is complete.
OM960400O