Single and multiple insertion of arylallene into the Rh-H bond to give (π-Allyl)rhodium complexes

Article abstract of DOI:10.1021/om9801711

The reaction of RhH(PPh₃)₄ at room temperature with excess phenylallene, (4-methylphenyl)allene, (4-methoxyphenyl)allene, (4-tert-butylphenyl)allene, (4-chlorophenyl)allene, and (4-fluorophenyl)allene results in the insertion of four arylallene molecules into the Rh-H bond to afford Rh{η³-CH₂C[CH(Ar)]C(=CHAr)CH ₂C(=CHAr)CH₂CH₂CH=CHAr)}(PPh₃) ₂ (1, Ar = C₆H₅; 2, Ar = C₆H₄Me-P; 3, Ar = C₆H₄OMe-p; 4, Ar = C₆H₄-t-Bu-p; 5, Ar = C₆H₄Cl-p; 6, Ar = C₆H₄F-p), respectively. NMR (¹H, ¹³C, and ³¹P) spectroscopy was used to characterize the (π-allyl)rhodium(I) complexes. Reaction of (4-methoxyphenyl)allene with RhD(PPh₃-d₁₅)₄ gives 3-d₃₁, Rh{η³-CH₂C[CH(Ar)]C(=CHAr)CH ₂C(=CHAr)CH₂CH₂CD=CHAr)}(PPh₃-d ₁₅)₂ (Ar = C₆H₄OMe-p), whose vinylene hydrogen is deuterated selectively. Complexes 1 and 3 do not react further with arylallene at room temperature. Reaction of arylallenes with an equimolar amount of RhH(CO)(PPh₃)₃ leads to the insertion of a molecule into the Rh-H bond to give the (π-allyl)rhodium complexes Rh(η³-CH₂CHCHC₆H ₄X-p)(CO)(PPh₃)₂ (9, X = Me; 10, X = OMe; 11, X = F; 12, X = Cl), while excess phenylallene reacts with the hydridorhodium complex to give a mixture of 1, Rh(η³-CH₂CHCHPh)(CO)(PPh₃)₂, and unreacted RhH(CO)(PPh₃)₃. A crystallographic study of 9 and ¹H NMR data for the complexes indicate that the aryl substituent has a syn orientation. The π-allyl complexes react with monosubstituted acetylenes to give trans-Rh(C≡CZ)(CO)(PPh₃)₂ (13, Z = Ph; 14, Z = C₆H₄Me-p; 15, Z = SiMe₃) accompanied by the generation of 1-arylpropene.

Full text of DOI:10.1021/om9801711

3044
Organometallics 1998, 17, 3044-3050
Sin gle a n d Mu ltip le In ser tion of Ar yla llen e in to th e
Rh -H Bon d To Give (π-Allyl)r h od iu m Com p lexes
J un-chul Choi, Kohtaro Osakada,* and Takakazu Yamamoto*
Research Laboratory of Resources Utilization, Tokyo Institute of Technology,
4259 Nagatsuta, Yokohama 226-8503, J apan
Received March 9, 1998
The reaction of RhH(PPh3)4 at room temperature with excess phenylallene, (4-methylphe-
nyl)allene, (4-methoxyphenyl)allene, (4-tert-butylphenyl)allene, (4-chlorophenyl)allene, and
(4-fluorophenyl)allene results in the insertion of four arylallene molecules into the Rh-H
bond to afford Rh{η3-CH2C[CH(Ar)]C(dCHAr)CH2C(dCHAr)CH2CH2CHdCHAr)}(PPh3)2 (1,
Ar ) C6H5; 2, Ar ) C6H4Me-p; 3, Ar ) C6H4OMe-p; 4, Ar ) C6H4-t-Bu-p; 5, Ar ) C6H4Cl-p;
6, Ar ) C6H4F-p), respectively. NMR (1H, 13C, and 31P) spectroscopy was used to characterize
the (π-allyl)rhodium(I) complexes. Reaction of (4-methoxyphenyl)allene with RhD(PPh3-
d15)4 gives 3-d31, Rh{η3-CH2C[CH(Ar)]C(dCHAr)CH2C(dCHAr)CH2CH2CD)CHAr)}(PPh3-
d15)2 (Ar ) C6H4OMe-p), whose vinylene hydrogen is deuterated selectively. Complexes 1
and 3 do not react further with arylallene at room temperature. Reaction of arylallenes
with an equimolar amount of RhH(CO)(PPh3)3 leads to the insertion of a molecule into the
Rh-H bond to give the (π-allyl)rhodium complexes Rh(η3-CH2CHCHC6H4X-p)(CO)(PPh3)2
(9, X ) Me; 10, X ) OMe; 11, X ) F; 12, X ) Cl), while excess phenylallene reacts with the
hydridorhodium complex to give a mixture of 1, Rh(η3-CH2CHCHPh)(CO)(PPh3)2, and
unreacted RhH(CO)(PPh3)3. A crystallographic study of 9 and 1H NMR data for the
complexes indicate that the aryl substituent has a syn orientation. The π-allyl complexes
react with monosubstituted acetylenes to give trans-Rh(CtCZ)(CO)(PPh3)2 (13, Z ) Ph; 14,
Z ) C6H4Me-p; 15, Z ) SiMe3) accompanied by the generation of 1-arylpropene.
Sch em e 1
In tr od u ction
The insertion of alkene and alkyne into Rh-H or
Rh-C bonds1 plays an important role in Rh-catalyzed
organic reactions such as hydrogenation and hydro-
formylation of alkenes and oligomerization and polym-
erization of alkenes and alkynes.2,3 Allene and substi-
tuted allenes were reported to undergo insertion of a
CdC double bond into a M-X bond (M ) transition
metal, X ) H, Cl, alkyl, acyl) to give π-allyl transition-
metal complexes rather than 2-propenyl complexes, as
shown in Scheme 1.4
π-Allyl Ni(II) and Pd(II) complexes initiate the po-
lymerization of allene and various substituted allenes
to give polymers with unique structures and block
copolymers with isocyanides.5 The polymerization in-
volves repeated insertion of allene into the bond between
the metal center and the π-allyl-coordinated growing
polymer (Scheme 2).
(1) (a) Pino, P.; Pacenti, F.; Bianci, M. In Organic Syntheses via
Metal Carbonyls; Wender, I., Pino, P. Eds.; Wiley: New York, 1977;
Vol. 2, pp 43, 233. (b) Homogeneous Catalysis with Metal Phosphine
Complexes; Pignolet, L. H., Ed.; Plenum: New York, 1983. (c) J ardine,
F. H. In The Chemistry of the Metal-Carbon Bond; Patai, S., Hartley,
F. R., Eds.; Wiley: Chichester, U.K., 1987; Vol. 4, p 734.
(2) (a) Hauptman, E.; Sabo-Etienne, S.; White, P. S.; Brookhart, M.;
Garner, J . M.; Fagan, P. J .; Calabrese, J . C. J . Am. Chem. Soc. 1994,
116, 8038. (b) Kaneko, Y.; Kanke, T.; Kiyooka, S.; Isobe, K. Chem. Lett.
1997, 23.
(3) (a) Wang, L.; Lu, R. S.; Bau, R.; Flood, T. C. J . Am. Chem. Soc.
1993, 115, 6999. (b) Tabata, M.; Yang, W.; Yokota, K. Polym. J . 1990,
22, 1105. (c) Tabata, M.; Yang, W.; Yokota, K. J . Polym. Sci., Part A:
Polym. Chem. 1994, 32, 1113. (d) Tabata, M.; Sadahiro, Y.; Nozaki,
Y.; Inaba, Y.; Yokota, K. Macromolecules 1996, 29, 6673. (e) Kishimoto,
Y.; Eckerle, P.; Miyatake, T.; Ikariya, T.; Noyori, R. J . Am. Chem. Soc.
1994, 116, 12131. (f) Kishimoto, Y.; Itou, M.; Miyatake, T.; Ikariya,
T.; Noyori, R. Macromolecules 1995, 28, 6662. (g). Kishimoto, Y.;
Miyatake, T.; Ikariya, T.; Noyori, R. Macromolecules 1996, 29, 5054.
(4) (a) Powell, P. Synthesis of η3-Allyl Complexes. In The Chemistry
of the Metal-Carbon Bond; Hartley, F. R., Patai, S., Eds.; Wiley: New
York, 1982; pp 355-357. (b) Schultz, R. G. Tetrahedron Lett. 1964,
301, 2809. (c) Lupin, M. S.; Shaw, B. L. Tetrahedron Lett. 1965, 883.
(d) Deeming, A. J .; J ohnson, B. F. G.; Lewis, J . J . Chem. Soc., Chem.
Commun. 1970, 598. (e) Stevens, R. R.; Shier, G. D. J . Organomet.
Chem. 1970, 21, 495. (f) Okamoto, T. Bull. Chem. Soc. J pn. 1971, 44,
1353. (g) Chisholm, M. H.; Clark, H. C.; Hunter, D. H. J . Chem. Soc.
D 1971, 809. (h) Hughes, R. P.; Powell, J . J . Organomet. Chem. 1972,
34, C51. (i) Clark, H. C.; Milne, C. R. C.; Wong, C. S. J . Organomet.
Chem. 1977, 136, 265. (j) Chisholm, M. H.; J ohns, W. S. Inorg. Chem.
1975, 14, 1189. (k) Hegedus, L. S.; Kambe, N.; Tamura, R.; Woodgate,
P. D. Organometallics 1983, 2, 1658. (l) Ru¨lke, R. E.; Kliphuis, D.;
Elsevier, C. J .; Fraanje, J .; Goubitz, K.; van Leeuwen, P. W. N. M.;
Vrieze, K. J . Chem. Soc., Chem. Commun. 1994, 1817. (m) Groen, J .
H.; Elsevier, C. J .; Vrieze, K.; Smeets, W. J . J .; Spek, A. L. Organo-
metallics 1996, 15, 3445. (n) Delis, J . G. P.; Groen, J . H.; Vrieze, K.;
van Leuuwen, P. W. N. M.; Veldman, N.; Spek, A. L. Organometallics
1997, 16, 551.
S0276-7333(98)00171-X CCC: $15.00 © 1998 American Chemical Society
Publication on Web 06/13/1998

(π-Allyl)rhodium Complexes
Sch em e 2
Organometallics, Vol. 17, No. 14, 1998 3045
Ta ble 1. Yield s a n d An a lytica l Da ta for th e
Com p lexes Rh {η3-CH2C[CH(Ar )]C(dCHAr )-
CH2C(dCHAr )CH2CH2CHdCHAr )}(P P h 3)2 (1-6)
anal.a
yield
complex
M
Ar
color (%)
C (%)
H (%)
1
2
3
4
5
6
Rh C6H5
Rh C6H4Me-p
Rh C6H4OMe-p
Rh C6H4-t-Bu-p red
Rh C6H4Cl-p
Rh C6H4F-p
red
red
red
60
72
85
70
72
88
78.99 (79.11) 6.09 (5.81)
79.09 (79.43) 6.62 (6.23)
74.71 (75.24) 5.99 (5.90)
b
69.84 (70.26) 5.03 (4.83)c
73.89 (74.22) 5.27 (5.10)
red
red
a
b
Calculated values are given in parentheses. Satisfactory
results were not obtained, although the complex was spectroscopi-
cally pure. c Cl: 11.02 (11.52).
sented. Part of this work has been reported in a
preliminary form.11
A similar type of allene insertion into Pd-π-allyl
bonds as well as into Pd-alkyl bonds was studied in
detail.6 On the other hand, Rh(I) complexes promote
the polymerization of allene and phenylallene7 or their
cyclooligomerization,8 depending on the auxiliary ligand.
The cyclooligomerization involves several unique reac-
tions such as cycloaddition of two allene molecules to
the metal center to give metallacyclopentane9 and
insertion of allene into the metal-carbon σ-bond of the
intermediate metallacycle complex. A detailed study of
the insertion of allene into Rh-H, Rh-alkyl, and Rh-
π-allyl bonds is significant with respect to the mecha-
nisms of allene polymerization and cyclooligomerization.
So far, there have been only a limited number of reports
on such reactions.7e,10 In this paper we report the
reaction of arylallene with hydridorhodium complexes
leading to the insertion of one or more arylallene
molecules into the Rh-H bond. Chemical properties of
the resulting π-allyl rhodium complexes are also pre-
Resu lts a n d Discu ssion
P r ep a r a tion of Rh Com p lexes 1-6 Con ta in in g
Ar yla llen e Tetr a m er a s th e π-Allyl Liga n d . Aryla-
llenes, including phenylallene, (4-methylphenyl)allene,
(4-methoxyphenyl)allene, (4-tert-butylphenyl)allene, (4-
chlorophenyl)allene, and (4-fluorophenyl)allene, react
with RhH(PPh3)4 in a 5:1 molar ratio at room temper-
ature to give (π-allyl)rhodium(I) complexes, Rh{η3-
CH2C[CH(Ar)]CHC(dCHAr)CH2C(dCHAr)CH2CH2CHd
CHAr)}(PPh ) (1, Ar ) C6H5; 2, Ar ) C6H4Me-p; 3, Ar
3 2
) C6H4OMe-p; 4, C6H4-t-Bu-p; 5, Ar ) C6H4Cl-p; 6, Ar
) C6H4F-p). The complexes were isolated in moderate
to high yields, as summarized in Table 1.
1
Figures 1 and 2 depict respectively the H and 13C-
{1H} NMR spectra of 3. The 1H NMR spectrum of 3-d31
obtained from the reaction of (4-methoxyphenyl)allene
with RhD(PPh3-d15)4 is also included in Figure 1. The
three 13C{1H} NMR resonances at δ 52.0, 71.9, and
116.8 exhibit splitting due to P-C and Rh-C coupling
and are assigned to carbons bonded to the Rh center in
an η3 form. The H-C COSY technique was useful for
assigning signals of three hydrogens attached to these
carbons. The 1H NMR signal at δ 4.93 and the 13C NMR
signal at δ 71.9 show a correlation peak, while peaks
are observed at the intersection of the 13C NMR signal
(5) (a) Otsuka, S.; Mori, K.; Suminoe, T.; Imaizumi, F. Eur. Polym.
J . 1967, 3, 73. (b) Krentsel, B. A.; Mushina, E. A.; Khar’kova, E. M.;
Shinshkina, M. V. Eur. Polym. J . 1975, 11, 865. (c) Ghalamkar-
Moazzam, M.; J acobs, T. L. J . Polym. Sci., Polym. Chem. 1978, 16,
615. (d) Tomita, I.; Kondo, Y.; Takagi, K.; Endo, T. Macromolecules
1994, 27, 4413. (e) Tomita, I.; Abe, T.; Takagi, K.; Endo, T. J . Polym.
Sci., Part A: Polym. Chem. 1995, 33, 2487. (f) Tomita, I.; Kondo, Y.;
Takagi, K.; Endo, T. Acta Polym. 1995, 46, 432. (g) Takagi, K.; Tomita,
I.; Endo, T. Chem. Lett. 1997, 1187. (h) Takagi, K.; Tomita, I.; Endo,
T. Macromolecules 1997, 30, 7386. (i) Endo, T.; Takagi, K.; Tomita, I.
Tetrahedron 1997, 45, 15187.
(6) (a) van Helden, R.; Kohll, C. F.; Medema, D.; Verberg, G.;
J onkhoff, T. Recl. Trav. Chim. Pays-Bas 1968, 87, 961. (b) Medema,
D.; van Heden, R.; Kohll, C. F. Inorg. Chim. Acta 1969, 3, 255. (c)
Medema, D.; van Helden, R. Recl. Trav. Chim. Pays-Bas 1977, 90, 304.
(d) Hughes, R. P.; Powell, J . J . Organomet. Chem. 1973, 60, 409. (e)
May, C. J .; Powell, J . J . Organomet. Chem. 1980, 184, 385.
(7) (a) Otsuka, S.; Nakamura, A. J . Polym. Sci., Part B: Polym. Lett.
Ed. 1967, 5, 973. (b) Scholten, J . P.; van der Ploeg, H. J . J . Polym.
Sci., Polym. Chem. Ed. 1972, 10, 3067. (c) Scholten, J . P.; van der Ploeg,
H. J . J . Polym. Sci., Polym. Chem. Ed. 1973, 11, 3205. (d) Leland, J .;
Boucher, J .; Anderson, K. J . Polym. Sci., Polym. Chem. Ed. 1977, 15,
2785. (e) So´va´go´, J .; Newton, M. G.; Mushina, E. A.; Ungva´ry, F. J .
Am. Chem. Soc. 1996, 118, 9589. (f) Choi, J .-C.; Osakada, K.; Yamagu-
chi, I.; Yamamoto, T. Appl. Organomet. Chem. 1997, 11, 957.
(8) (a) J ones, F. N.; Lindsey, R. V. J . Org. Chem. 1968, 33, 3838. (b)
Otsuka, S.; Nakamura, A.; Tani, K.; Ueda, S. Tetrahedron Lett. 1969,
297. (c) Otsuka, S.; Nakamura, A.; Minamida, H. J . Chem. Soc. D 1969,
191. (d) Scholten, J . P.; van der Ploeg, H. J . Tetrahedron Lett. 1972,
1685.
1
at δ 52.0 and two H NMR signals at δ 3.56 and 2.70.
These results suggest coordination of the 1,2-disubsti-
tuted π-allylic ligand to the Rh center and are consistent
with the crystallographic structure of 3 shown in eq 1.
(9) (a) Ingrosso, G.; Immirzi, A.; Porri, L. J . Organomet. Chem. 1973,
60, C35. (b) Ingrosso, G.; Porri, L.; Pantini, G.; Racanelli, P. J .
Organomet. Chem. 1975, 84, 75. (c) Immirzi, A. J . Organomet. Chem.
1974, 81, 217. (d) Choi, J .-C.; Sarai, S.; Koizumi, T.; Osakada, K.;
Yamamoto, T. Organometallics 1998, 17, 2037.
The signals due to two CH2 hydrogens, Hf and Hg,
appear as an AB quartet at δ 3.62 and 3.78, while the
(10) (a) Brown, C. K.; Mowat, W.; Yagupsky, G.; Wilkinson, G. J .
Chem. Soc. A 1971, 850. (b) Osakada, K.; Choi, J .-C.; Koizumi, T.;
Yamaguchi, I.; Yamamoto, T. Organometallics 1995, 14, 4962.
(11) Osakada, K.; Choi, J . C.; Yamamoto, T. J . Am. Chem. Soc. 1997,
119, 12390.

3046 Organometallics, Vol. 17, No. 14, 1998
Choi et al.
gens of the 4-methoxyphenyl groups overlap markedly
1
with large peaks of PPh3 hydrogens; in contrast, the H
NMR spectrum of 3-d31, having much smaller PPh3
peaks, shows singlet signals for Hd and He at δ 7.44 and
6.87, respectively. The deuterium from the hydrido
ligand is situated at the Hl position because the 1H NMR
spectrum of 3-d31 does not contain the corresponding
peak and shows the peak of Hm at δ 6.32 as a singlet.
The correlation peaks in the H-C COSY NMR spectrum
of 3 are consistent with the above assignment of 1H
NMR signals; 13C NMR peak assignments are listed in
Table 2. The 31P{1H} NMR spectrum of 3 exhibits two
doublets of doublets due to two magnetically nonequiva-
lent P nuclei arising from the coordination of the
unsymmetric π-allyl ligand. Complexes 1, 2, and 4-6
show NMR peaks at positions similar to those of 3, as
summarized in Tables 2 and 3, and have similar 1,2-
disubstituted π-allylic ligands, respectively, formed via
the insertion of four molecules of the corresponding
para-substituted phenylallene.
Reaction 1 in a 1:5 molar ratio gives complexes 1-6
selectively, among several other products such as Rh
complexes with a coordinating arylallene tetramer with
a structure different from 1-6 and complexes with a
π-allylic ligand formed via the insertion of one, two,
three, or five molecules of arylallene into the Rh-H
bond. The reaction of phenylallene with RhH(PPh3)4
in a 3:1 molar ratio affords complex 1 in 35% yield after
repeated recrystallization, while an equimolar reaction
also gives 1, but in a lower yield. These results suggest
that isolation of complexes 1-6 is due not only to
preferential crystallization of the products but also to
their formation with high selectivity.
F igu r e 1. 1H NMR spectra of (a) 3 and (b) 3-d31 (400 MHz
in benzene-d6). Signals at δ 3.6 in the spectrum of 3-d31
contain overlapping peaks of Hc, Hg′ and an impurity
derived from the RhD(PPh3-d15)4 used.
Scheme 3 depicts a plausible pathway for the forma-
tion of complexes 1-6.
The insertion of an arylallene molecule into the Rh-H
bond gives the (π-allyl)rhodium complex A, similar to
an equimolar reaction of allene and phenylallene with
RhH(CO)(PPh3)3.10 Selective deuteration at the Hl
position of 3-d31 prepared from the reaction of (4-
methoxyphenyl)allene with RhD(PPh3-d15)4 is consistent
with the generation of the (π-allyl)rhodium intermediate
A rather than the other 2-propenylrhodium complexes
(M-C(dCHAr)CH3 and M-C(dCH2)CH2Ar). Structure
D found in the crystallographic study of 3 strongly
indicates the presence of intermediates B and C, con-
taining respectively a dimer and a trimer of arylallene
as an η1-bonded alkenyl ligand. The insertion of one
arylallene molecule into the Rh-π-allyl bond of A gives
the alkenylrhodium complex B, which undergoes further
insertion of arylallene into the Rh-C bond to give an
alkenyl group coordinated complex (C). The fourth
arylallene molecule reacts with C to afford complex D,
having the π-allylic-coordinated arylallene tetramer. We
have no clear rationale for selective formation of product
D, although steric demands of the oligomer bonded to
the Rh center seem to influence the structure of the
product and of the intermediate complexes. The forma-
tion of complex A involves an initial dissociation of a
PPh3 ligand to form RhH(PPh3)3, followed by the inser-
tion of an arylallene molecule into the Rh-H bond.12
Liberation of a second PPh3 molecule, which may occur
F igu r e 2. 13C{1H} NMR spectrum of 3 (100 MHz in
benzene-d6). Signals due to C4, C5, C7, C8, C11, and C12
overlap with PPh3 carbon signals. Positions of the signals
due to C5, C8, C11, and C12 were determined to appear at δ
132.0, 130.3, 128.6, and 130.5, respectively, on the basis
of the H-C COSY spectrum.
four CH2 hydrogens Hh-Hk are observed at δ 2.28, 2.40,
and 2.65 as complex signals due to H-H coupling. Two
resonances at δ 6.03 and 6.32 are assigned to trans
vinylene hydrogens Hl and Hm, respectively, on the basis
of the splitting pattern caused by H-H coupling. The
singlets at δ 3.34, 3.33, 3.30, and 3.27 are assigned to
hydrogens of four OMe groups of the π-allylic ligand.
The signals due to Hd and He and the aromatic hydro-
(12) Yamamoto, T.; Miyashita, S.; Naito, Y.; Komiya, S.; Ito, T.;
Yamamoto, A. Organometallics 1982, 1, 808.

(π-Allyl)rhodium Complexes
Organometallics, Vol. 17, No. 14, 1998 3047
Ta ble 2. 13C a n d 31P NMR Da ta for Com p lexes 1-6a
complex
13C{1H} NMR
31P{1H} NMRb
1
2
3
130.5 (C12), 130.4 (C11), 116.6 (C2, J (CRh) ) 7 Hz),76.1 (C1, J (CRh) ) 24 Hz,
42.0 (193, 24), 39.8 (200, 24)
J (CP) ) 7.3 Hz), 52.9 (C3, J (CRh) ) 29 Hz, J (CP) ) 9.2 Hz), 38.7 (C6),
32.2, 31.8 (C9 and C10
)
131.5 (C12), 130.4 (C11), 116.7 (C2, J (CRh) ) 6 Hz), 76.2 (C1, J (CRh) ) 24 Hz,
J (CO) ) 9 Hz), 52.4 (C3, J (CRh) ) 26 Hz, J (CO) ) 7 Hz), 38.6 (C6), 32.4,
31.8 (C9 and C10), 21.24, 21.20, 21.16 (CH3)
42.4 (192, 24), 40.3 (200, 24)
42.4 (193, 24), 40.5 (200, 24)
135.44, 135.39, 135.3, 134.8, 134.6, 134.5, 132.4, 132.33, 132.28, 132.0, 131.7,
131.5, 131.4, 130.6 (C6H5 and C6H4), 130.5 (C12), 130.3, 130.0 (C6H5 and C6H4),
128.6 (C11), 116.8 (C2, J (C2Rh))7.4 Hz), 114.5, 114.3, 114.2, 113.4 (C6H4),
71.9 (C1, J (C1Rh) ) 23.9 Hz, J (C1P) ) 7.4 Hz)), 54.8, 54.74, 54.68 (OCH3),
52.0 (C3, J (C3Rh) ) 29.5 Hz, J (C3P) ) 9.2 Hz), 38.5 (C6),
32.4 (C10), 31.7 (C9)
4
5
6
130.3 (C12), 129.8 (C11), 116.9 (C2, J (CRh) ) 7 Hz), 76.1(C1, J (CRh) ) 24 Hz,
J (CP) ) 7 Hz), 52.7 (C3, J (CRh) ) 26 Hz, J (CP) ) 6 Hz), 38.8 (C6), 31.9,
31.8 (C9 and C10), 31.64, 31.55 (CH3)
42.4 (192, 24), 40.2 (200, 24)
42.4 (192, 24), 40.5 (200, 24)
41.8 (193, 24), 39.8 (200, 24)
130.0 (C12), 129.5 (C11), 115.8 (C2, J (CRh) ) 7 Hz), 74.3 (C1, J (CRh) ) 24 Hz,
J (CP) ) 9 Hz), 52.6 (C3, J (CRh) ) 26 Hz, J (CP) ) 7 Hz), 38.6 (C6),
31.8, 31.5 (C9 and C10
)
116.0 (C2, J (CRh) ) 7 Hz), 74.4(C1, J (CRh) ) 24 Hz, J (CP) ) 7 Hz),
52.3 (C3, J (CRh) ) 28 Hz, J (CP) ) 6 Hz), 38.4 (C6), 31.9, 31.5 (C9 and C10
)
a
b
Peaks due to C11 and C12 are significantly overlapped with the phenyl carbon peaks. J (RhP) and J (PP) (Hz) are in parentheses.
Ta ble 3. 1H NMR Da ta for Com p lexes 1-6a
complex
Ha
Hb
Hc
Hf, g
Hh-k
Hl
Hm
otherb
1
2
4.89 (br) 2.60 (d, 5) 3.47 (br) 3.70, 3.58 (AB q, 17) 2.25 (3H), 2.52 (1H) (m) 6.01 (ddd, 16, 8, 8) 6.23 (d, 16)
4.91 (br) 2.71 (d, 6) 3.52 (br) 3.75, 3.60 (AB q, 18) 2.28 (1H), 2.61 (2H),
6.08 (ddd, 16, 8, 8) 6.30 (d, 16) 2.09, 2.12, 2.13,
2.16 (CH3)
6.03 (ddd, 16, 8, 8) 6.32 (d, 16) 3.27, 3.30, 3.33,
3.34 (OCH3)
2.71 (1H) (m)
4.93 (br) 2.70 (d, 4) 3.56 (br) 3.78, 3.62 (AB q, 18) 2.28 (1H), 2.40 (2H),
2.65 (1H) (m)
3
4
4.98 (br) 2.77 (d, 8) 3.56 (br) 3.80, 3.62 (AB q, 18) 2.29 (1H), 2.35 (2H),
2.69 (1H) (m)
6.17 (ddd, 16, 8, 8) 6.36 (d, 16) 1.19, 1.25 (CH3)
5
6
4.60 (br) 2.58 (d, 4) 3.33 (br) 3.52, 3.45 (AB q, 18) 2.10 (3H), 2.36 (1H) (m) 5.78 (ddd, 16, 8, 8) 6.00 (d, 16)
4.67 (br) 2.57 (d, 4) 3.38 (br) 3.55, 3.48 (AB q, 18) 2.13 (3H), 2.40 (1H) (m) 5.79 (ddd, 16, 8, 8) 6.08 (d, 16)
a
b
Measured at 25 °C in C6D6 (400 MHz). Figures in parentheses are the coupling constants. Aromatic hydrogen peaks are observed
at δ 6.4-7.9. Aromatic hydrogens other than PPh3 ligands are overlapped with those due to PPh3. The hydrogens of complex 3 were
analyzed by using PPh3-d15 to show the peaks at 7.56, 7.25, 7.20, 6.89, 6.76, and 6.70 (d, J ) 8 Hz).
during the reactions shown in Scheme 3, involves the
sequence η3-allyl f alkenyl, alkenyl f alkenyl, and
alkenyl f η3-allyl.
The formation of 1, even in the equimolar reaction of
phenylallene and RhH(PPh3)4, suggests that the initial
insertion of the substrate into the Rh-H bond to give
A is much slower than the subsequent insertion of three
arylallene molecules into the Rh-C bond. The reactant
difference toward insertion of arylallene between RhH-
(PPh3)4 and intermediates A-C can be attributed to the
requirement of PPh3 dissociation from RhH(PPh3)4.
All these results are summarized as follows. RhH-
(PPh3)4 reacts with arylallene to give complexes 1-6,
containing the arylallene tetramer as the π-allylic
ligand. Once an arylallene molecule has reacted with
the Rh-H bond to give a (π-allyl)rhodium complex, the
subsequent insertion of three arylallene molecules
proceeds smoothly to give a product with the 1,2-
disubstituted π-allylic ligand. The structure of the
π-allylic ligand of the isolated major product does not
depend on the substituent on the phenyl group and
Reaction of a large excess of phenylallene with RhH-
(PPh3)4 (10:1) at room temperature gives rise to isolation
of 1 in high yield. Complexes 1 and 3 do not react
further with arylallene at room temperature. The 1,2-
disubstituted π-allylic ligand in 1 and 3 (structure D in
Scheme 3) forms a more stable bond than the Rh-C σ
bond of B and C and is more sterically demanding than
the monosubstituted π-allyl group in A. These features
of 1 and 3 prevent the complexes from further insertion
of arylallene into the Rh-allyl bond. The poor reactivity
of 1 and 3 toward insertion of arylallene into the Rh-C
bond contrasts with the labile nature of the bond
between Ni and the 1,2-disubstituted π-allylic ligand,
which is found in the living polymer of monosubstituted
allene promoted by Ni(II) complexes.5

3048 Organometallics, Vol. 17, No. 14, 1998
Choi et al.
Sch em e 3
F igu r e 3. ORTEP drawing of Rh(η3-CH2CHCHC6H4Me-
p)(CO)(PPh3)2 (9) with 50% probability atomic displacement
ellipsoids. Hydrogen atoms were omitted for simplicity.
indicates a reaction route via (π-allyl)-, alkenyl-, and
alkenylrhodium intermediates in that order to give the
final product.
P r ep a r a t ion a n d R ea ct ion of R h (η3-CH 2CH -
CHAr )(CO)(P P h 3)2. Previously we reported that the
equimolar reaction of phenylallene and of methoxyallene
with RhH(CO)(PPh3)3 results in the single insertion of
the substrate into the Rh-H bond to give Rh(η3-CH2-
CHCHPh)(CO)(PPh3)2 (7) and Rh(η3-CH2CHCHOMe)-
(CO)(PPh3)2 (8), respectively.10 Reactions of the p-sub-
stituted phenylallenes with RhH(CO)(PPh3)3 also give
the complexes Rh(η3-CH2CHCHC6H4X-p)(CO)(PPh3)2 (9,
X ) Me; 10, X ) OMe; 11, X ) F; 12, X ) Cl).
F igu r e 4. ORTEP drawing of trans-Rh(CtCPh)(CO)-
(PPh3)2 (13) with 50% probability atomic displacement
ellipsoids. Hydrogen atoms were omitted for simplicity.
ature to give Rh(CtCPh)(CO)(PPh3)2 (13), accompanied
by the liberation of 1-phenylpropene in quantitative
yield.
The complexes were characterized by NMR spectros-
copy as well as X-ray crystallography of 9 (Figure 3),
showing a syn orientation of the aryl substituent of the
π-allylic ligand.
Analogous alkynylrhodium and -iridium(I) complexes
were prepared from the reaction of phenylacetylene with
alkoxido complexes.13 Complex 13 has a trans coordi-
nation around the Rh center, as depicted in Figure 4.
The alkynyl ligand bonded to the Rh center shows
negligible elongation of the CtC triple bond or shorten-
ing of the Rh-C bond, indicating only a small contribu-
tion from a vinylidene structure for the ligand (M-d
CdC+-Ph). Similar reactions of (π-allyl)rhodium
complexes with terminal alkynes produce the alkynyl-
Multiple insertion of phenylallene into the Rh-H
bond of RhH(CO)(PPh3)3 and into the Rh-π-allyl bond
of 7 was examined. The former reaction at room
temperature afforded mixtures of 1 and 7 along with
unreacted RhH(CO)(PPh3)3, while the latter gave a
mixture of 1 and 7 in a 23:77 molar ratio. No other Rh
complexes were contained in the reaction mixture. In
this reaction, insertion of phenylallene into the Rh-C
bond occurs smoothly until the stable complex 1 is
formed or does not occur at all. The monosubstituted
π-allylic ligand in the above complexes shows higher
reactivity than do 1 and 3. The (π-allyl)rhodium
complex 7 reacts with phenylacetylene at room temper-
(13) Ferna´ndez, M. J .; Esteruelas, M. A.; Covarrubias, M.; Oro, L.
A. J . Organomet. Chem. 1990, 381, 275. For other alkynylrhodium
complexes, see: Abu Salah, O. M.; Bruce, M. I. J . Chem. Soc., Chem.
Commun. 1974, 688. Abu Salah, O. M.; Bruce, M. I. Aust. J . Chem.
1977, 30, 2639.

(π-Allyl)rhodium Complexes
Organometallics, Vol. 17, No. 14, 1998 3049
Sch em e 4
nyl)allene (362 mg, 2.5 mmol) at room temperature. The
initial orange solution turned red on stirring. After 2 h the
solvent was reduced to ca. 1 mL under vacuum. Slow addition
of hexane to the solution caused the separation of an orange
solid, which was collected by filtration, washed twice with
hexane, and dried in vacuo to give 1 as an orange-red
microcrystalline solid (510 mg, 85%). The complex thus
obtained was analytically pure but can be recrystallized from
acetone to give red single crystals (80% yield).
rhodium(I) complexes with CO and PPh3 ligands, as
shown in eq 3. The reaction of the π-allylic rhodium
Preparation of 2-6 was carried out analogously.
P r ep a r a tion of 9-12. To a toluene (10 mL) solution of
RhH(CO)(PPh3)3 (327 mg, 0.36 mmol) was added (4-meth-
ylphenyl)allene (56 mg, 0.43 mmol) at room temperature.
After 14 h, the solvent was evaporated to dryness. Addition
of hexane to the resulting brown paste caused separation of a
yellow solid, which was collected by filtration and recrystal-
lized from THF-hexane to give 9 as yellow crystals (180 mg,
64%). Anal. Calcd for C47H41OP2Rh: C, 71.76; H, 5.25.
Found: C, 71.52; H, 5.26. 1H NMR (400 MHz, in C6D6): δ 1.7
(br, 2H, syn and anti), 2.14 (s, 3H, CH3), 3.79 (d, 1H, J ) 9
Hz, anti), 5.20 (dddd, 1H, J ) 9, 7, 7, and 2 Hz, central), 7.09-
7.50 (m, 34H, aromatic).
complex with 18 electron metal center can be explained
by a reaction path that involves the initial formation of
16 electron species through η3 to η1 conversion of the
allylic ligand or dissociation of a PPh3 ligand, followed
by oxidative addition of C-H bond of the terminal
alkyne (Scheme 4). Reductive elimination of 1-arylpro-
pene from the Rh(III) intermediate seems to occur more
rapidly than that of the terminal alkyne.
The present study has disclosed that arylallene
smoothly reacts with hydridorhodium complexes to
result in single or quadruple insertion of the unsatur-
ated molecule into the Rh-H bond at room temperature.
The 1,2-disubstituted (π-allyl)rhodium complexes show
poor reactivity toward insertion of the arylallene mol-
ecule into their Rh-π-allyl bond. These results may be
related to the low efficiency of hydridorhodium com-
plexes as the initiators of arylallene polymerization.7d,f
Complexes 10-12 were prepared analogously. Data for 10
are as follows. Yield: 48%. Anal. Calcd for C47H41O2P2Rh:
C, 70.33; H, 5.15. Found: C, 70.71; H, 5.40. 1H NMR (400
MHz, in C6D6): δ 1.7 (br, 2H, syn and anti), 3.35 (s, 3H, OCH3),
3.82 (d, 1H, J ) 9 Hz, anti), 5.14 (dddd, 1H, J ) 9, 7, 7, and
2 Hz, central), 7.51-6.85 (m, 34H, aromatic). IR (KBr) ν(Ct
O): 1943 cm-1. Data for 11 are as follows. Yield: 62%. Anal.
Calcd for C46H38FOP2Rh: C, 69.88; H, 4.84. Found: C, 69.72;
H, 5.14. 1H NMR (400 MHz in C6D6): δ 1.5 (br, 2H, syn and
anti), 3.65 (d, 1H, J ) 10 Hz, anti), 5.08 (dddd, 1H, J ) 10, 7,
7, and 2 Hz, central), 6.85-7.46 (m, 34H, aromatic). IR
(KBr): ν(CtO), 1951 cm-1. Data for 12 are as follows. Yield:
61%. Anal. Calcd for C46H38COP2Rh: C, 68.45; H, 4.74.
Found: C, 67.70; H, 4.74. 1H NMR (400 MHz at 25 °C, in
CD2Cl2): δ 1.7 (br, 2H, syn and anti), 3.25 (d, 1H, J ) 10 Hz,
anti), 4.81 (dddd, 1H, J ) 10, 7, 7, and 2 Hz, central), 7.15-
7.46 (m, 34H, aromatic). 1H NMR (400 MHz at -70 °C, in
CD2Cl2): δ 0.55 (dd, 1H, J ) 22 and 8 Hz, anti), 1.55 (dd, 1H,
J ) 11 and 6 Hz, syn), 3.08 (ddd, 1H, J ) 15, 9, and 7 Hz,
anti), 4.58 (br, 1H, central), 6.98-7.66 (m, 34H, aromatic).
31P{1H} NMR (160 MHz at -40 °C in CD2Cl2): δ 21.9 (dd, J )
141 and 35 Hz), 41.4 (dd, J ) 157 and 35 Hz). IR (KBr): ν-
Exp er im en ta l Section
Gen er a l Con sid er a tion s, Mea su r em en t, a n d Ma ter ia ls.
Manipulation of the Rh complexes was carried out under
nitrogen or argon using standard Schlenk techniques. RhH-
(PPh3)4, RhD(PPh3-d15)4, RhH(CO)(PPh3)3, arylallenes, and
complex 7 were prepared according to the literature.10b,14 NMR
spectra (1H, 13C, and 31P) were recorded on a J EOL EX-400
spectrometer. 31P{1H} NMR peak positions were referenced
to external 85% H3PO4. Elemental analyses were carried out
using a Yanaco MT-5 CHN autocorder.
(CtO), 1948 cm-1
.
Rea ction of Alk yn es w ith (π-Allyl)r h od iu m Com p lexes
7, 8, a n d 11. A mixture of 7 (555 mg, 0.72 mmol) and
phenylacetylene (183 mg, 1.8 mmol) was dissolved in toluene
(10 mL) at room temperature. After 1 h, formation of 1-phe-
nylpropene in a quantitative yield was confirmed by GC
analysis. The solvent was evaporated to dryness. Addition
of hexane to the resulting oily product caused the separation
of a yellow solid, which was collected by filtration and
recrystallized from Et2O to give 13 as yellow crystals (81%).
Anal. Calcd for C45H35OP2Rh: C, 71.44; H, 4.66. Found: C,
P r ep a r a tion of 1-6. To a toluene (10 mL) solution of
RhH(PPh3)4 (570 mg, 0.50 mmol) was added (4-methoxyphe-
(14) (a) Levinson, J . J .; Robinson, S. D. J . Chem. Soc. A 1970, 2497.
(b) Strauss, S. H.; Diamond, S. E.; Mares, F.; Shriver, D. F. Inorg.
Chem. 1978, 17, 3064. (c) J ardin, F. H. Polyhedron 1982, 1, 569 and
references therein. (d) Osakada, K.; Matsumoto, K.; Yamamoto, T.;
Yamamoto, A. Organometallics 1985, 4, 857. (e) Moore, W. R.; Ward,
H. R. J . Org. Chem. 1962, 27, 4179.

3050 Organometallics, Vol. 17, No. 14, 1998
Choi et al.
70.93; H, 4.71. 1H NMR (400 MHz, in C6D6): δ 6.67 (d, 2H, J
) 8 Hz, ortho), 6.78 (t, 1H, J ) 8 Hz, para), 6.87 (t, 2H, J ) 8
Hz, meta), 7.05 and 7.99 (m, 30H, C6H5). 13C{1H} NMR (100
MHz, in CD2Cl2): δ 123.7 (d, CtCPh, J (RhC) ) 11 Hz), 125.1
(C≡CPh), 127.6, 127.9, 129.8, 131.1, 135.0, 135.1, 194.1 (d, CO,
J (RhC) ) 59 Hz). 31P{1H} NMR (160 MHz in CD2Cl2) δ 34.0
(d, J (RhP) ) 121 Hz). IR (KBr): ν(CtC), 2336 cm-1; ν(CtO),
polarization effects and an empirical absorption correction (Ψ
scan) were applied. Atomic scattering factors were taken from
the literature.15 The structure was solved by a combination
of direct methods and subsequent Fourier techniques. The
positional and thermal parameters of non-hydrogen atoms
were refined anisotropically, while hydrogen atoms were
located by assuming an ideal geometry.
1968 cm-1
.
X-ray data for 9: monoclinic, P21/c (No. 14), a ) 9.576(3) Å,
b ) 18.477(9) Å, c ) 21.752(4) Å, â ) 91.78(2)°,V ) 3847 Å3,
Z ) 4, Dcalc ) 1.358 g cm-3, F(000) ) 1624, µ(Mo KR) ) 5.61
cm-1 for monochromated Mo KR radiation (λ ) 0.710 69 Å). R
(Rw) ) 0.056 (0.040) for 3992 reflections with I > 3σ(I) among
7216 unique reflections (Rint ) 0.055). GOF ) 2.40. X-ray
data for 13: monoclinic, P21/a (No. 14), a ) 12.295(2) Å, b )
18.635(5) Å, c ) 17.673(5) Å, â ) 103.86(2)°,V ) 3930 Å3, Z )
4, Dcalc ) 1.278 g cm-3, F(000) ) 1552, µ(Mo KR) ) 5.47 cm-1
for monochromated Mo KR radiation (λ ) 0.710 69 Å). R (Rw)
) 0.052 (0.049) for 3460 reflections with I > 3σ(I) among 8773
unique reflections (Rint ) 0.214). GOF ) 1.28.
Similar reaction of phenylacetylene with 7 in a 1:1 molar
ratio gave 13 in 80% yield. Reaction of phenylacetylene with
11 in a 3:1 molar ratio did not occur at room temperature,
whereas reactions of (4-methylphenyl)acetylene and of (tri-
methylsilyl)acetylene with 11 (3:1 molar ratio) gave 14 (83%)
and 15 (90%), respectively. Data for 14 are as follows. Anal.
Calcd for C46H37OP2Rh: C, 71.69; H, 4.84. Found: C, 70.40;
H, 4.96. 1H NMR (400 MHz in C6D6): δ 1.95 (s, 3H, CH3), 6.60
(d, 2H, J ) 8 Hz, meta), 6.69 (d, 1H, J ) 8 Hz, meta), 7.05 (m,
18H, C6H5), 8.02 (d, 12H, J ) 7 Hz, C6H5). 13C{1H} NMR (100
MHz, in CD2Cl2): δ 21.2, 122.1 (d, CtCPh, J (RhC) ) 40 Hz),
123.8 (d, CtCPh, J (PC) ) 11 Hz), 126.1, 127.9, 128.4, 129.8,
131.1, 134.4, 134.8, 135.1, 194.1 (d, CO, J (RhC) ) 59 Hz).
31P{1H} NMR (160 MHz in CD2Cl2): δ 33.7 (br). Data for 15
are as follows. Anal. Calcd for C42H39OP2SiRh: C, 67.02; H,
5.22. Found: C, 66.48; H, 5.21. 1H NMR (400 MHz, in C6D6):
δ -0.17 (s, 9H, CH3), 7.12 (m, 18H, C6H5), 7.96 (d, 12H, J ) 7
Hz, C6H5). 13C{1H} NMR (100 MHz, in CD2Cl2): δ 0.94, 128.1,
129.0 (d, CtCSi, J (PC) ) 9 Hz), 129.8, 135.2, 144.9 (d, Ct
CSi, J (RhC) ) 39 Hz), 194.1 (d, CO, J (RhC) ) 59 Hz). 31P{1H}
NMR (160 MHz in CD2Cl2): δ 33.5 (br).
Ack n ow led gm en t. This work was financially sup-
ported by a Grant-in-Aid for Scientific Research from
the Ministry of Education, Science, Culture, and Sports
of J apan.
Su p p or tin g In for m a tion Ava ila ble: Tables giving crys-
tallographic data for complexes 9 and 13 (17 pages). Ordering
information is given on any current masthead page.
X-r a y Cr ysta llogr a p h ic Stu d y. Crystals of 9 and 13
suitable for crystallography were obtained by recrystallization
from Et2O at -20 °C. The data were collected on a Rigaku
AFC5R diffractometer at ambient temperature (23 °C) using
the ω scan mode (2θ e 50°). Correction for Lorentz and
OM9801711
(15) International Tables for X-ray Crystallography; Kynoch: Bir-
mingham, U.K., 1974; Vol. IV.