New rhodacyclopentane with phenylvinylidene substituents, mer-[Rh{CH2C(=CHPh)C(=CHPh)CH2}Cl(PMe3) 3]. Structure and formation through concerted cycloaddition of phenylallene molecules to [RhCl(PMe3)3]

Article abstract of DOI:10.1039/a701859b

[RhCl(PMe₃)₃] reacts with an excess of phenylallene to give a new rhodacyclopentane, mer-[Rh{CH₂C(=CHPh)-C(=CHPh)CH₂}Cl(PMe₃) ₃] 1, which is not obtained via the reaction of [RhCl(η²-CH₂=C=CHPh)(PMe₃)₃] 2 with phenylallene.

Full text of DOI:10.1039/a701859b

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New rhodacyclopentane with phenylvinylidene substituents,
mer-[Rh{CH2C(NCHPh)C(NCHPh)CH2}Cl(PMe3)3]. Structure and formation
through concerted cycloaddition of phenylallene molecules to [RhCl(PMe3)3]
Kohtaro Osakada,* Jun-Chul Choi, Susumu Sarai, Take-aki Koizumi and Takakazu Yamamoto*
Research Laboratory of Resources Utilization, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226, Japan
[RhCl(PMe3)3] reacts with an excess of phenylallene to give
new rhodacyclopentane, mer-[Rh{CH2C(NCHPh)-
spectrum are in accord with the structure obtained by X-ray
crystallography.
Reaction of a reduced amount of phenylallene with
[RhCl(PMe3)3] has been examined in order to obtain an insight
a
C(NCHPh)CH2}Cl(PMe3)3] 1, which is not obtained via the
2
reaction of [RhCl(h -CH2NCNCHPh)(PMe3)3] 2 with phe-
for the pathway of reaction (1). Reaction in a 1.2:1 ratio in
nylallene.
2
hexane
results
in
the
formation
of
[RhCl(h -
CH2NCNCHPh)(PMe3)3] 2 which is isolated as the hexane
Several complexes of Ti, Ta, Co, Ir and Ni have been reported
to undergo addition of two alkene molecules to give the
corresponding saturated metallacyclopentanes.1 Similar for-
mation of metallacycles from the 2:1 reaction of allene and
transition-metal complexes is much less common,2 while the
reaction is involved as a crucial step in cyclooligomerization of
allene or substituted allene promoted by metal complexes.3
Chlororhodium(i) complexes catalyze polymerization4 or cy-
clooligomerization5 of 1,2-dienes depending on the ligands
bonded to the Rh center. Formation of a rhodacyclopentane
from allene would be intriguing in relation to the the mechanism
of the above cyclooligomerization of the 1,2-dienes catalyzed
by Rh complexes. Here, we report the addition of phenylallene
to [RhCl(PMe3)3], to give a novel rhodacyclopentane which is
structurally characterized.
insoluble product.§
Ph
Me3P
H
H
C
Cl
C
(2)
[RhCl(PMe3)3] +
H2C
C C
Rh
C
Me3P
Ph
Me3P
H
H
(1.2 equiv.)
2
Fig. 2 shows the molecular structure of 2 which shows a
trigonal-bipyramidal coordination around the Rh centre with
P(1) and P(3) at the apical positions.‡ Elongation of the
p-coordinated CNC double bond [CH2NC 1.406(9), CNCHPh
C(7)
[RhCl(PMe3)3] reacts with 3 equiv. of phenylallene to give
mer-[Rh{CH2C(NCHPh)C(NCHPh)CH2}Cl(PMe3)3]
1
as
C(6)
C(8)
shown in eqn. (1).†
Ph
C(5)
C(9)
C(22)
Me3P
H
H
Cl
(1)
[RhCl(PMe3)3] +
H2C
C C
Rh
C(4)
H
Me3P
Me3P
Ph
C(24)
Ph
C(23)
P(2)
(3 equiv.)
1
C(2)
C(3)
The reaction mixture does not contain any other rhodacy-
clopentanes that would be formed through addition of phenyl-
allene in a different orientation of the double bonds. Fig. 1
shows the molecular structure of 1 which has an octahedral
coordination around the Rh center with three PMe3 ligands at
meridional coordination sites.‡ Three C–C bond distances in the
five-membered chelate ring are quite similar, while the Rh–C(1)
bond [2.16(1) Å] is longer than the Rh–C(10) bond [2.061(1) Å]
owing to a larger trans influence of PMe3 relative to Cl. The
C–C bond distances [1.49(2) Å] are significantly longer than the
corresponding bond of the platinacyclopentane prepared from
dimerization of cycloheptatetraene in the presence of a
platinum(0) complex.2b Both of the two CNC double bonds in 1
have Z structure owing to less steric congestion around the s-cis
diene moiety than the other possible geometry of the double
bonds.
Cl
C(25)
C(1)
C(10)
Rh
C(11)
C(12)
P(3)
C(27)
C(21)
C(13)
C(14)
P(1)
C(20)
C(26)
C(18)
C(17)
C(19)
C(15)
C(16)
Fig. 1 ORTEP drawing of 1 at 30% probability level. Selected bond
distances (Å) and angles (°): Rh–Cl 2.503(3), Rh–P(1) 2.331(5), Rh–P(2)
2.326(4), Rh–P(3) 2.368(3), Rh–C(1) 2.16(1), Rh–C(10) 2.06(1),
C(1)–C(2) 1.49(2), C(2)–C(3) 1.38(2), C(2)–C(11) 1.49(2), C(10)–C(11)
1.49(2), C(11)–C(12) 1.35(2); Cl–Rh–P(1) 86.9(1), Cl–Rh–P(2) 85.5(1),
Cl–Rh–P(3) 95.8(1), Cl–Rh–C(1) 94.3(4), Cl–Rh–C(10) 176.3(3),
P(1)–Rh–P(2) 168.9(1), P(2)–Rh–P(3) 94.6(2), P(1)–Rh–P(3) 94.1(2),
P(1)–Rh–C(1) 88.4(4), P(1)–Rh–C(10) 92.7(4), P(2)–Rh–C(1) 84.1(4),
P(2)–Rh–C(10) 94.3(4), P(3)–Rh–C(1) 169.6(4), P(3)–Rh–C(10) 87.8(3),
C(1)–Rh–C(10) 82.0(5), Rh–C(1)–C(2) 107.6(9), C(1)–C(2)–C(3) 125(1),
C(1)–C(2)–C(11) 111(1), C(11)–C(2)–C(3) 122(1), Rh–C(10)–C(11)
112.6(8), C(10)–C(11)–C(12) 128(1), C(2)–C(11)–C(10) 112(1),
C(2)–C(11)–C(12) 119(1).
The 13C{1H} NMR spectrum gives rise to signals due to the
CH2 carbons at d 22.26 and 13.21. The former peak, with a large
J(CP) value (77 Hz), is assigned to the carbon bonded trans to
PMe3 and the latter to carbon trans to Cl. Two 1H NMR signals
due to the CH2 hydrogens are observed at d 3.02 and 2.11,
which are assigned to the CH2 group trans to PMe3 and trans to
1
Cl, respectively, based on the H–13C COSY spectrum. The
1
other H and 13C NMR signals as well as the 31P{1H} NMR
Chem. Commun., 1997
1313

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Footnotes
C(15)
C(16)
* E-mail: kosakada@res.titech.ac.jp
C(14)
† To a toluene (8 ml) solution of [RhCl(PMe3)3] (158 mg, 0.43 mmol) was
added phenylallene (150 mg, 1.3 mmol) at room temp. The initial pale
yellow solution gradually turned pale brown accompanied by deposition of
an off-white solid which was collected by filtration after the reaction for 8
h, and dried in vacuo to give 1 (203 mg, 79%).
P(2)
C(13)
P(3)
C(2)
‡ Crystal data: for 1: C27H43ClP3Rh, Mr = 598.92, orthorhombic, space
group Pbca (no. 61), a = 35.023(6), b = 13.823(3), c = 12.155(2) Å,
U = 5884 Å3, Z = 8, Dc = 1.353 g cm23, m(Mo-Ka) = 8.37 cm21
(graphite-monochromated radiation, l = 0.71069 Å), F(000) = 2496. The
data collection was made on a Rigaku AFC5R diffractometer at ambient
temperature (293 K) using w scan mode for Lorentz and polarization effects.
An empirical absorption correction (y scan) was applied. Of the unique
5877 reflections with 2q @ 55°, 1959 reflections with I > 3 s(I) were used
in the refinement. A total of 289 parameters (non-hydrogen atoms modelled
anisotropically) were refined with w = [s(Fo)]22. Hydrogen atoms were
placed in idealised geometries and included in the structure calculation
without refinement of the parameters. The structure converged to R = 0.054
and Rw = 0.044. For 2: C18H35ClP3Rh, Mr = 482.75, orthorhombic, space
group P212121 (no. 19), a = 12.926(2), b = 15.979(2), c = 11.307(3) Å,
U = 2336 Å3, Z = 4, Dc = 1.373 g cm23, m(Mo-Ka) = 10.36 cm21
(graphite-monochromated radiation, l = 0.71069 Å), F(000) = 1000. The
data collection and absorption correction were carried out similarly to 1. Of
the unique 2528 reflections with 2q @ 55°, 2066 reflections with I > 3s(I)
were used in the refinement. A total of 208 parameters were refined with
w = [s(Fo]22 and the structure converged to R = 0.038 and Rw = 0.029.
Treatment of hydrogen atoms is similar to 1. CCDC 182/513.
§ To a hexane (8 ml) dispersion of [RhCl(PMe3)3] (115 mg, 0.31 mmol) was
added phenylallene (44 mg, 0.38 mmol) at room temp. Stirring the mixture
for 26 h led to separation of a yellow solid which was collected by filtration
and dried in vacuo. Recrystallization from thf–hexane afforded 2 as yellow
crystals (85 mg, 57%).
¶ Dissociation of PMe3 from 2 is not thermodynamically favoured. The
equilibrium constant for 2 = 3 + PMe3 is 5.1 3 1024 l mol21 even at 60 °C
and is probably much smaller near 25 °C although precise measurement of
the equilibrium constant was not feasible. Crystallographic results of 3
which show a square-planar coordination around the Rh center will be
reported separately.
Cl
C(18)
C(12)
Rh
C(17)
P(1)
C(3)
C(1)
C(11)
C(9)
C(10)
C(4)
C(8)
C(5)
C(6)
C(7)
Fig. 2 ORTEP drawing of 2 at 50% probability level. Selected bond
distances (Å) and angles (°): Rh–Cl 2.540(2), Rh–P(1) 2.320(2), Rh–P(2)
2.323(2), Rh–P(3) 2.325(2), Rh–C(1) 2.126(7), Rh–C(2) 1.988(6),
C(1)–C(2) 1.406(9), C(2)–C(3) 1.353(9); Cl–Rh–P(1) 84.79(7), Cl–Rh–
P(2) 97.80(7), Cl–Rh–P(3) 83.36(7), Cl–Rh–C(1) 118.3(2), Cl–Rh–C(2)
158.0(2), C(1)–Rh–C(2) 39.8(3), P(1)–Rh–P(2) 96.74(7), P(2)–Rh–P(3)
96.94(7), P(1)–Rh–P(3) 162.98(7), C(1)–C(2)–C(3) 142.1(7).
Ph
Ph
H
L
L
C
20 °C
H
H
Cl
C
Cl
Rh
L
+
H2C
C
CHPh
Rh
L
L
C
L
H
Ph
H
2
1
Scheme 1
References
1 (a) A. R. Fraser, P. H. Bird, S. A. Bezman, J. R. Shapley, R. White and
J. A. Osborn, J. Am. Chem. Soc., 1973, 95, 597; (b) J. X. McDermott,
M. E. Wilson and G. M. Whitesides, J. Am. Chem. Soc., 1976, 98, 6529;
(c) R. H. Grubbs and A. Miyashita, J. Organomet. Chem., 1978, 161, 371;
(d) S. J. McLain, C. D. Wood and R. R. Schrock, J. Am. Chem. Soc., 1979,
101, 4558; (e) S. A. Cohen, P. R. Auburn and J. E. Bercaw, J. Am. Chem.
Soc., 1983, 105, 1136; (f) P. Binger, T. R. Martin, R. Benn, A. Rufinska
and G. Schroth, Z. Naturforsch. Teil B, 1984, 39, 993; (g) K. Mashima
and H. Takaya, Organometallics, 1985, 4, 1464.
2 (a) G. K. Barker, M. Green, J. A. K. Howard, J. L. Spencer and
F. G. A. Stone, J. Chem. Soc., Dalton Trans., 1978, 1839; (b)
W. R. Winchester, M. Gawron, G. J. Palenik and W. M. Jones,
Organometallics, 1985, 4, 1894.
1.353(9) Å] as well as a bend of the cumulated double bonds
[C(1)–C(2)–C(3) 142.1(7)°] indicate the presence of significant
back-donation from the Rh center to the phenylallene ligand.
The 1H NMR spectrum of 2 above 25 °C shows partial
liberation of a PMe3 ligand to afford a square-planar rhodium(i)
2
complex [Rh(h -CH2NCNCHPh)Cl(PMe3)2] 3 which is isolated
from the mixture and characterized by X-ray crystallo-
graphy.¶
Reaction of 2 and phenylallene in a 1:2 molar ratio in toluene
for 8 h at 20 °C does not give 1 but causes quantitative recovery
of 2 as shown in Scheme 1.
The results are in contrast with previous reports indicating
that several transition-metal complexes containing p-coordi-
nated alkenes react further with alkenes to give the corre-
sponding metallacyclopentane.1d,f,g The present study has
disclosed that the p-coordinated phenylallene complex 2, with
an 18 electron Rh center, is not a precursor of the metallacycle
1 in reaction (1) and that formation of 1 proceeds through direct
3 D. J. Pasto, N.-Z. Huang and C. W. Eigenbrot, J. Am. Chem. Soc., 1985,
107, 3160.
4 S. Otsuka and A. Nakamura, J. Polym. Sci., Part B: Polym. Lett. Ed.,
1967, 5, 973; J. P. Scholten and H. J. van der Ploeg, J. Polym. Sci., Polym.
Chem. Ed., 1972, 10, 3067; J. P. Scholten and H. J. van der Ploeg,
J. Polym. Sci., Polym. Chem. Ed., 1973, 11, 3205; J. Leland, J. Boucher
and K. Anderson, J. Polym. Sci., Polym. Chem. Ed., 1977, 15, 2785.
5 F. N. Jones and R. V. Lindsey, J. Org. Chem., 1968, 33, 3838; S. Otsuka,
A. Nakamura and H. Minamida, Chem. Commun., 1969, 191; J. P.
Scholten and H. J. van der Ploeg, Tetrahedron Lett., 1972, 1685.
cycloaddition
of
two
phenylallene
molecules
to
[RhCl(PMe3)3].
This work was financially supported by a Grant-in-Aid for
Scientific Research from the Ministry of Education, Science,
Sports and Culture, Japan.
Received in Cambridge, UK, 17th March 1997; Com.
7/01859B
1314
Chem. Commun., 1997