A convenient synthesis of a sterically protected 1,4-diphosphabutatriene and its pentacarbonyltungsten complexes

Article abstract of DOI:10.1016/S0022-328X(97)00616-5

1,4-Bis(2,4,6-tri-t-butylphenyl)-1,4-diphosphabutatriene was obtained by the copper-mediated coupling reaction of 1-halo-2-phosphaethenyllithiums. The 1,4-diphosphabutatriene formed mono- and bis-pentacarbonyltungsten complexes, and the X-ray analysis of

Full text of DOI:10.1016/S0022-328X(97)00616-5

Ž
.
Journal of Organometallic Chemistry 553 1998 135–140
A convenient synthesis of a sterically protected 1,4-diphosphabutatriene
and its pentacarbonyltungsten complexes
)
Shigekazu Ito, Kozo Toyota, Masaaki Yoshifuji
Department of Chemistry, Graduate School of Science, Tohoku UniÕersity, Aoba, Sendai 980-77, Japan
Received 14 May 1997; received in revised form 2 September 1997
Abstract
Ž
.
1,4-Bis 2,4,6-tri-t-butylphenyl -1,4-diphosphabutatriene was obtained by the copper-mediated coupling reaction of 1-halo-2-phos-
phaethenyllithiums. The 1,4-diphosphabutatriene formed mono- and bis-pentacarbonyltungsten complexes, and the X-ray analysis of the
bis-tungsten complex revealed end-on type coordination with the trans configuration. q 1998 Elsevier Science S.A.
Keywords: 1,4-Diphosphabutatriene; Copper-mediated coupling reaction; Tungsten pentacarbonyl complex; X-ray analysis; Steric protection
1. Introduction
2. Results and discussion
Sterically protected and multiple-bonded
organophosphorus compounds are currently of interest
2.1. Copper-mediated coupling reaction of 1-halo-2-
phosphaethenyllithiums
w x
Ž
1 . Utilizing the 2,4,6-tri-t-butylphenyl group abbrevia-
ted to the Ar group as a protecting group, we have
.
Previous methods for the preparation of 1,4-diphos-
reported the synthesis and characterization of
phabutatriene 1 are depicted in Scheme 1. Markl and
¨
w
x
w x
diphosphenes 2,3 , phosphaethenes 4 , and so on.
Phosphacumulenes are also attractive compounds, and
we and others have been successful in the synthesis and
w
x
Kreitmeier 14 reported the reaction of silylated
ethynylphosphine with dichlorophosphine 2 affording
Ž
w
x
.
the butatriene 1 3q1 system, Method A , while we
reported the preparative method of repeated utilization
of the sequence of addition of dichlorocarbene to the
P5C bond and rearrangement to allene as the modified
w
x
characterization of 1-phosphaallenes 5–7 , 1,3-diphos-
w
x
w
x
phaallenes 8–11 , and 1-phosphabutatrienes 12,13 .
Although 1,4-diphosphabutatriene 1 was synthesized by
w
x
w x
Markl and Kreitmeier 14 and ourselves 15 , the prop-
¨
Ž
w
x
Doering–Moore–Skattebøl homologation 2q1q1
erties of 1 have little been revealed. Indeed, there exist
trans and cis isomers for 1, but no X-ray crystallo-
graphic analysis has been carried out. We now report on
a simple and convenient preparation of 1 and formation
of its pentacarbonyltungsten complexes. Furthermore,
X-ray analysis of one of the tungsten complexes was
performed as the first example of the E-1,4-diphos-
phabutatriene system.
.
w x
system, Method B 15 . These methods, however, re-
quire several elaborating steps.
On the other hand, 2,2-dihalo-1-phosphaethenes 3a,
3b are easily available from 2 and can be derived to the
corresponding 1-halo-2-phosphaethenyllithiums 4a, 4b
by the halogen–metal exchange reaction at low temper-
w
x
ature 16,17 . Halophosphaethenyllithium reagents 4 are
the phosphorus analogues of alkylidene carbenoids
w
x
18,19 and useful synthons for novel organophosphorus
w
x
w x
compounds. In fact, van der Sluis et al. 20 and us 21
reported on the reactions of 4a with several carbonyl
compounds affording the multifunctionalized phos-
phaethenes.
)
Corresponding author.
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

(
)
136
S. Ito et al.rJournal of Organometallic Chemistry 553 1998 135–140
Ž .
Ž .
Ž .
Ž .
Ž .
Ž . w
x
Ž .
Scheme 1. Reagents: a LAH; b CCl4, AIBN; c LiC[CTms; d MeLirTMEDA; e Mg; f PhCH2 NEt3 Cl, NaOH, CHCl3; g t-BuLi;
q
h Li C10 Hy8 P
.
Ž .
Ž
.
Ž
w
x
When chlorophosphaethenyllithium 4a Z-isomer
Ž .
preparation of 1,4-diphosphabutatriene 1 2q2 sys-
.
was generated in the presence of copper II chloride,
1,4-diphosphabutatriene and 1,4-diphospha-1,3-
butadiene 5a were obtained 22 , while Niecke et al.
tem . Moreover, halophosphaethenyllithiums 4a, 4b are
1
useful for preparation of 2,3-dihalo-1,4-diphospha-1,3-
butadienes 5a, 5b, which might serve as another type of
novel intermediates in the organophosphorus com-
w
x
w
x
23 reported the dimerization reaction of 4a to 1,3-di-
w
x
phosphacyclobutane-2,4-diyl as shown in Scheme 2.
However, the yields of 1 and 5a were dependent on the
quenching time and temperatures as well as on the
presence or absence of oxygen. Although 1 was ob-
pounds 24 .
2.2. Complex formation and structural analysis
w
x
tained in the absence of oxygen 22 , the yields of 1
1,4-Diphosphabutatriene 1 is an attractive ligand for
metal complexes because of its having various kinds of
possible coordination modes. Previously, we reported
on an end-on type coordinated pentacarbonyltungsten
1
were strongly dependent on quenching time. In this
Ž .
reaction, copper II chloride might first react with 2 mol
of 4a to form an organocopper intermediate, and upon
warming, the reductive elimination from the intermedi-
ate occurs to afford 1. Furthermore, butatriene 1 was
obtained always as a mixture of ErZs4:1 isomers and
Ž
.
complex of 4,4-diphenyl-1- 2,4,6-tri-t-butylphenyl -1-
w
x
phosphabutatriene 25 .
Ž
.
Butatriene 1 ErZs4:1 was allowed to react with
2
Ž
. Ž
.
almost insoluble in most common organic solvents.
an excess amount of W CO THF to give the dicoor-
5
1-Bromo-2-phosphaethenyllithium 4b was derived
dinated complex 6. When 1 was allowed to react with 1
Ž
.
Ž
. Ž
.
from 3b as a mixture of ErZ-isomer 1:5 , and afforded
equivalent of W CO THF , a peak due to monocoor-
5
dinated complex 7 was observed by 31 P NMR together
3
Ž
.
1 andror butadiene 5b Scheme 2, Table 1 . In con-
trast, in the case of 4b, butatriene 1 was the major
product at y788C, accompanied with 5b as the minor
product. Because of the high leaving ability of bromide
compared to chloride, butatriene 1 might be formed
mainly from 4b. At y958C, however, 4b afforded only
butadiene 5b in 22% yield. Thus the present copper-
mediated coupling reaction of 1-halo-2-phosphaethenyl-
lithiums 4a, 4b is a simple and efficient method for the
Ž
.
with that due to 6 Scheme 3 . Although 7 could not be
isolated, probably due to its instability, 6 was purified
by silica-gel column chromatography. Both E- and
Z-isomers were considered to be formed, but only 6 of
E-configuration was obtained as a single isomer even if
starting from an ErZs4:1 mixture of 1, thus the
Z-isomer of 6 was not detected. In the 31 P NMR
spectrum of complex 6, a peak appeared at dP 105.0
CDCl3 accompanied by satellite peaks due to 183 W of
Ž
.
14% natural abundance.
The structure of 6 was unambiguously established by
the X-ray crystallographic analysis. Fig. 1 shows an
ORTEP drawing of the molecular structure for 6 and
1
w
x
In the previous communication 22 , we reported that the yield of
1 was 63% using 3a after immediate quenching in the absence of
oxygen, but the yields depend on the reaction conditions especially
on the quenching time. For example, no 1 was obtained after 30-min
stirring at y788C instead of immediate warming. Under the oxida-
tive conditions described in this report, the yields of 1 and 5 were
reproducible without any tricky reaction conditions, although in some
cases the yields were slightly lower than those reported before.
2 The ErZ ratio of 4:1 seems to be an equilibrium ratio in
chloroform at 295 K. The 31 P NMR peak due to the Z-isomer
disappeared upon heating at 318 K and it became visible again in the
same ErZ ratio as before heating, when the mixture was cooled
Table 1
Ž
Copper-mediated coupling reaction of 4 giving 1 andror 5 isolated
.
yields
Ž
.
Ž
.
Ž
.
Substrate Temperature 8C
Yield of 1 %
Yield of 5 %
4a
4a
4b
4b
0
y78
y78
y95
54
0
47
0
7
46
13
22
down at 295 K.
3 In P NMR 81 MHz , 4b was observed as ErZs1:5 mixture
31
Ž
.
Ž
.
at 210 K; dP THF-d8 E-4b, 369.7; Z-4b, 254.6.
a: X5Cl. b: X5Br. See Section 3 for the reaction conditions.

(
)
S. Ito et al.rJournal of Organometallic Chemistry 553 1998 135–140
137
Scheme 2.
Table 2 shows some selected bond lengths and angles.
The molecule has a center of symmetry and the struc-
ture was solved as a half of the molecule. Complex 6
clearly shows end-on type coordination at both phos-
Hitachi U-3210 spectrometer. Microanalyses were per-
formed at the Instrumental Analysis Center of Chem-
istry, Faculty of Science, Tohoku University. X-ray
diffraction data were collected on a Rigaku AFC-7S
four-circle diffractometer. The starting phosphaethenes
3a and 3b were prepared according to literature meth-
phorus atoms of E-butatriene configuration. The P–W
)
˚
Ž .
bond distance is 2.492 2 A. The P1–C1 and C1–C1
˚
˚
Ž .
Ž .
w
x
distances are 1.656 6 A and 1.25 1 A, respectively,
ods 16,17 .
which are very similar to those for the tungsten complex
Ž
.
of 4,4-diphenyl-1- 2,4,6-tri-t-butylphenyl -1-phos-
3.1. Copper-mediated coupling reaction of 1-chloro-2-
phosphaethenyllithium 4a
w
x
phabutatriene 25 . The W, P, C1, C2 atoms are copla-
˚
Ž
.
nar within 0.0 A , and the plane makes an angle of
83.18 with the mean aromatic ring of the 2,4,6-tri-t-
butylphenyl group.
Ž
.
To a solution of 3a 108.3 mg, 0.301 mmol in THF
Ž
.
Ž
8 ml was added butyllithium 0.319 mmol, 1.68 M
solution in hexane, 1 Ms1 mol dmy3 at y788C.
.
Since the structure of the free ligand 1 has not been
solved yet, this is the first example of structural analysis
of 1,4-diphosphabutatriene system, showing that the
system is very similar to that of 1-phosphabutatriene.
Ž .
Ž
After being stirred for 5 min, copper II chloride 0.270
.
mmol was added to the reaction mixture and the mix-
ture was warmed to y308C and stirred for 1 h. The
mixture was then warmed to 08C and oxygen gas cooled
at y788C was bubbled through the mixture for 5 min
Ž
.
3. Experimental
ca. 32 mmol , and a concentrated aqueous NaHSO3
solution was then added. After being warmed to room
Ž
All experiments were carried out under an argon
atmosphere with dry solvents, unless otherwise speci-
fied. The melting points were determined with a Yanag-
imoto micromelting-point apparatus MP-J3 and are not
temperature, ammonia 10% NH3 in concentrated aque-
.
ous NH4Cl solution was added to the reaction mixture.
The reaction mixture was extracted with chloroform,
dried with MgSO4, and the solvent was evaporated in
vacuo. The residue was washed with hexane and buta-
triene 1 was obtained as yellow crystals 44.0 mg .
Moreover, 0.6 mg of butatriene 1 and 6.8 mg of butadi-
ene 5a were obtained from the washings in a similar
1
corrected. H and 13C NMR spectra were recorded on a
Bruker AC200P or a Bruker AM600 spectrometer. 31 P
NMR spectra were obtained with a Bruker AC200P
spectrometer using 85% H3PO4 as an external standard.
NMR spectra were recorded at room temperature unless
otherwise noted. MS spectra were taken on a JEOL
HX-110. IR spectra were recorded on a Horiba FT-300
spectrometer. UV–vis spectra were obtained with a
Ž
.
Ž
.
w
x
manner; butatriene 1, 44.6 mg 54% yield 14,15 ,
butadiene 5a, 6.8 mg 7% yield 22 .
Ž
. w x
When this reaction was carried out at y788C as
described in Section 3.2 for 4b, only butadiene 5a was
Scheme 3.

(
)
138
S. Ito et al.rJournal of Organometallic Chemistry 553 1998 135–140
q
q
Ž
.
.
Ž
.
Ž
.
obtained as a coupling compound 46% yield . 1: Mix-
7 , 401 ArP2C2Cl2 ; 90 , 335 ArPC2Cl ; 14 , 299
q
q
ArPC2 y1; 6 , 275 ArP y1; 34 , and 57 t Buq;
Ž
.
Ž
.
Ž
ture of ErZs4:1 isomers; yellow crystals, mp 2508C
31
Ä1
4
Ž
.
.
35
Ž
.
decomp. ; P H NMR 81 MHz, CDCl3, 298 K
100 . Found: mrz 646.3373. Calcd. for C38 H58Cl2 P2:
2
E-1: ds180.6, Z-1: ds170.0. 5a: Yellow prisms
M, 646.3391.
1
Ž
.
Ž
.
Ž
toluene , mp 253–2548C decomp. ; H NMR 200
.
Ž
.
Ž
MHz, CDCl3 ds1.34 18H, s, p-t-Bu , 1.51 36H, s,
3.2. Copper-mediated coupling reaction of 1-bromo-2-
phosphaethenyllithium 4b
13
.
Ž
.
Ä1
4
Ž
Ž
o-t-Bu , and 7.42 4H, m, m-Ar ; C H NMR 150
. .
.
Ž
Ž
MHz, CDCl3 ds31.3 s, p-C CH3 , 32.7 brs,
3
Ž
. .
Ž
Ž
. .
Ž
Ž .
To a solution of 3b 173.1 mg, 0.386 mmol in THF
14 ml was added butyllithium 0.391 mmol at
Ž .
y1008C. After being stirred for 10 min, copper II
o-C CH3 , 35.1 s, p-C CH3 , 37.9 brs, o-
3
Ž
. . 3
Ž
.
Ž
Ž
.
Ž
.
1
C CH3 , 122.0 brs, m-Ar , 135.5 dd, JPC s27.6
3
4
.
Ž
.
Hz, JPC s25.3 Hz, ipso-Ar , 151.0 s, p-Ar , 154.0
1
2
Ž
.
.
Ž
Ž
.
brs, o-Ar , and 167.4 dd, JPC s26.5 Hz, JPC s18.0
chloride 0.200 mmol was added to the reaction mix-
ture and stirred for 1 h at y788C. Then oxygen gas was
similarly bubbled through the reaction mixture for 5
min and then a concentrated aqueous solution of
NaHSO3 was added. After being warmed to room tem-
31
Ä1
4
Ž
.
Hz, P5C ; P H NMR 81 MHz, CDCl3 ds248.0;
y1
Ž
.
Ž
.
Ž
.
.
IR KBr 1595 cm ; UV hexane 242 log ´ 4.44
Ž
.
Ž
.
Ž
Ž
and 366 nm 4.28 ; MS 70 eV, EI mrz rel. intensity
q
q
q
Ž
.
Ž
.
.
650 M q4; 2 , 648 M q2; 8 , 646 M ; 12 , 611
q
q
t
q
Ž
.
Ž
.
Ž
Ž
perature, ammonia 10% NH3 in a concentrated aque-
M yCl; 4 , 589 M y Bu; 5 , 575 M y2Cly1;
Ž
.
Ž .
Fig. 1. Molecular structure of 6. Hydrogen atoms are omitted for clarity. As for the disordered carbon atoms, C 13 –C 15 , only those with the
Ž
.
higher occupancy factor 0.51 are shown.

(
)
S. Ito et al.rJournal of Organometallic Chemistry 553 1998 135–140
139
Table 2
Ž
. Ž
. Ž
W CO THF ca. 0.6 mmol, prepared by irradiation to
5
Some selected bond lengths and angles for 6
Ž
.
a THF solution of W CO at 58C for 3 h with a
w6
x.
˚
Ž .
Ž .
Bond angle 8
Bond length A
medium-pressure Hg lamp 26 , and being stirred for
10 h at room temperature. The solvent was evaporated
in vacuo, and the residue was passed through silica gel
Ž .
2.492 2
1.840 6
1.656 6
1.25 1
2.049 8
2.038 9
2.036 9
2.056 9
Ž .
100.4 3
P1–W
C1–P1–C2
P1–C1–C1)
W–P1–C1
Ž .
Ž .
178.4 8
P1–C2
P1–C1
C1–C1)
W–C20
W–C21
W–C22
W–C23
W–C24
Ž .
Ž .
117.6 2
Ž
.
column hexanerEt3N 10:1 . The solvent was evapo-
Ž .
Ž .
141.9 2
W–P1–C2
rated to leave the tungsten complex 6. After being
Ž .
Ž .
92.2 2
P1–W–C20
P1–W–C21
P1–W–C22
P1–W–C23
P1–W–C24
C20–W–C21
C20–W–C22
C20–W–C23
C20–W–C24
C21–W–C22
C21–W–C23
C21–W–C24
C22–W–C23
C22–W–C24
C23–W–C24
Ž
.
washed with acetone, 24.0 mg of 6 was obtained 49% .
6: Deep blue prisms hexane , mp 2208C decomp. ; H
Ž .
Ž .
97.8 2
1
Ž
.
Ž
.
Ž .
Ž .
88.5 2
Ž
.
Ž
.
Ž .
Ž .
85.8 2
NMR 200 MHz, CDCl3 ds1.32 18H, s, p-t-Bu ,
4
Ž .
Ž .
174.9 3
1.997 9
Ž
.
.
Ž
1.67 36H, s, o-t-Bu , and 7.42 4H, dd, JPH s2.2 Hz,
7
13
Ž .
Ä1
4
Ž
.
91.0 3
JPH s1.9 Hz, m-Ar ; C H NMR 150 MHz, CDCl3
Ž .
175.7 3
Ž
Ž
. . . .
Ž
Ž
Ž
ds31.0 s, p-C CH3 , 34.5 s, o-C CH3 , 35.1 s,
3
3
Ž .
93.9 3
Ž
. .
Ž
Ž
. .
Ž
Ž
.
p-C CH3 , 39.1 s, o-C CH3 , 123.4 s, m-Ar ,
Ž .
89.7 3
3
3
Ž
.
Ž
.
.
Ž .
129.5 s, ipso-Ar , 152.4 s, p-Ar , 155.7 s, o-Ar ,
84.7 4
1
2
Ž .
173.8 3
Ž
.
175.0 dd, JPC s30.0 Hz, JPC s26.0 Hz, P5C ,
2
Ž .
86.9 3
Ž
.
Ž
.
195.5 brs, COeq , and 199.8 d, JPC s18.9 Hz, COax ;
Ž .
90.4 4
31
Ä1
4
Ž
.
Ž
P H NMR 81 MHz, CDCl3 ds105.0 satellite,
Ž .
89.9 3
1
4
.
Ž
.
JPW s169.6 Hz, JPW s109.0 Hz ; IR KBr 2065,
Ž .
89.4 3
2000, 1955, and 1940 cmy1; UV–vis hexane lmax
Ž
.
.
Numbers in parentheses are estimated standard deviations.
Ž
Ž
.
Ž
.
Ž
.
Ž
log ´ 206 5.05 , 230 5.05 318 4.05 , and 609 nm
q
.
Ž
.
Ž
4.83 ; FAB-MS mrz 1225 M q1 and 548 ArPC-
.
q
ous NH4Cl solution was added to the reaction mixture.
The reaction mixture was extracted with chloroform,
dried with MgSO4, and the solvent was evaporated in
vacuo. The residue was washed with hexane to give
butatriene 1 as yellow crystals 52.5 mg, 47% yield .
Moreover, 18.9 mg of butadiene 5b was obtained from
the washings after silica-gel column chromatographic
.
CPAr y2Meq2 . Anal. Found: C, 47.25; H, 4.62%;
Calcd. for C48 H58O10 P2W2: C, 47.08; H, 4.77%.
Ž
. Ž
.
The reaction of 1 with 1 equivalent of W CO THF
gave monocoordinated complex 7 together with bis-
tungsten complex 6 and the starting material 1. 7:
5
Ž
.
31
Ä1
4
Ž
.
P H NMR 81 MHz, CDCl3 ds181.5 and 105.3
3
Ž
.
ABq, JPP s315.1 Hz .
Ž
.
treatment 13% yield .
When this reaction was carried out at y958C, only
3 .4 . X -ra y stru ctu re d eterm in a tio n o f
][ ( ) ] ( )
butadiene 5b was obtained as a coupling compound
[
ArP5C5C5 PAr W CO 5
6
2
Ž
.
Ž
22% yield . 5b: Yellow crystals, mp 220–2218C de-
1
.
Ž
.
Ž
comp. ; H NMR 200 MHz, CDCl3 ds1.34 18H, s,
The complex 6 was recrystallized from hexane. 1r2
P C48 H58O10 P2W2 , Mr s 612.31, monoclinic, space
Ž . Ž .
.
Ž
.
Ž
.
p-t-Bu , 1.53 36H, s, o-t-Bu , and 7.42 4H, m, m-Ar ;
13
Ä1
4
Ž
.
Ž
C H NMR 50 MHz, CDCl3 ds31.3 s, p-
4
6
group P21rn, a s 11.116 6 , b s 12.65 1 , c s
Ž
. .
Ž
C CH3 , 32.8 dd, JPC s4.0 Hz, JPC s4.0 Hz,
3 . .
Ž
Ž
. .
Ž
3
˚
˚
Ž .
Ž .
Ž .
18.973 5 A, bs104.56 3 8. Vs2581 2 A , Zs4,
Dc s1.575 g cmy3, ms45.70 cmy1. The 4792 unique
reflections with 2u-50.08 were recorded on a four-
circle diffractometer using graphite-monochromated
Ž
o-C CH3 , 35.1 s, p-C CH3 , 38.0 brs, o-
3
1
Ž
. . 3
Ž
.
.
Ž
C CH3 , 122.1 brs, m-Ar , 138.1 dd, JPC s28.3
3
4
Ž
.
Hz, JPC s28.3 Hz, ipso-Ar , 151.2 s, p-Ar , 153.5
2
5
Ž
Ž
.
dd, JPC s2.3 Hz, JPC s2.3 Hz, o-Ar , and 160.4
Ž
.
1
2
31
Mo-K a radiation. Of these, 3443 with F)3s F
were judged as observed. The structure was solved
using SHELXS86 27 . The methyl carbons C 13 ,
C 14 , C 15 on C 12 are disordered occupancy fac-
tors for the dominant: 0.51 . The nonhydrogen atoms
.
Ä1
4
dd, JPC s23.1 Hz, JPC s19.9 Hz, P5C ; P H
Ž
.
Ž
.
NMR 81 MHz, CDCl3 ds261.6; IR KBr 1595
w
x
Ž
.
cmy1; UV hexane lmax log ´ 246 4.38 and 362
Ž
.
Ž
.
Ž
.
Ž
.
Ž
.
Ž
.
Ž
Ž
.
Ž
.
Ž
.
nm 4.00 ; MS 70 eV, EI mrz rel. intensity 738
.
q
q
q
Ž
Ž
.
Ž
.
Ž
.
M q4; 15 , 736 M q2; 23 , 734 M ; 9 , 677
except the disordered C-atoms were refined anisotropi-
cally. Hydrogen atoms were included but not refined.
Rs0.033, Rw s0.041. Further details of the crystal
structure investigation are available from the Cambridge
Crystallographic Data center, 12 Union Road, CB-Cam-
q
t
q
q
.
Ž
.
Ž
M y Bu; 10 , 655 M yBr; 54 , 601 M yBr
t
q
t
q
.
Ž
Ž
.
Ž
y Buq3; 31 , 599 M yBry Buq1; 27 , 575 M
q
q
.
.
Ž
y2Bry1; 19 , 368 ArPCBr q1; 23 , 275 ArP y1;
q
q
.
Ž
.
Žt
.
24 , 231 Ar yCH3 y1; 100 , and 57 Bu ; 50 .
79
Found: 734.2373; Calcd. for C38 H Br2 P2: 734.2380.
58
Ž
.
bridge CB2 1EZ UK .
3.3. Formation of pentacarbonyltungsten complexes of
1
Ž
.
To a solution of butatriene 1 23.0 mg, 39.9 mmol in
1
4
4 Satellite signals were tentatively assigned as JPW and JPW
.
Ž
.
Ž
.
THF 15 ml was added a THF 5 ml solution of

(
)
140
S. Ito et al.rJournal of Organometallic Chemistry 553 1998 135–140
w x
9
H.H. Karsch, H.U. Reisacher, G. Muller, Angew. Chem., Int.
¨
Acknowledgements
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Ed. Engl. 23 1984 618.
w
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10 H.H. Karsch, F.H. Kohler, H.U. Reisacher, Tetrahedron Lett. 25
¨
This work is supported in part by the grant-in-aid for
Scientific Research from the Ministry of Education,
Science, Sports and Culture, Japanese Government
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1984 3687.
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08454193 . One of the authors S.I. is grateful to
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