Insertion reactions of alkynes into the Ru-H bond of indenylruthenium(II) hydride complexes. Mechanism of the reaction of phenylacetylene with [RuH(η5-C9H7)(dppm)] (dppm = bis (diphenylphosphino)methane)

Article abstract of DOI:10.1021/om970489d

The indenyl complexes [RuX(η⁵-C₉H₇)(dppm)] (dppm = bis(diphenylphosphino)methane, X = H, D) react with phenylacetylene to give the products of syn addition [Ru{(E)-CH=CXPh)(η⁵-C⁹H⁷)(dppm)] in toluene, in the temperature range 40-80 °C. The indenyl complexes [RuH(η⁵-C₉H₇)LL′] (L = L′ = PMe₂Ph; L = PPh₃, L′ = PMe₂Ph; L = PPh₃, L′ = PMe₃; LL′ = dppe) and [RuH(η⁵-Me₃C₉H₄)(CO)(PPh ₃)] and the cyclopentadienyl complex [RuH(η⁵-C₅H₅)(dppm)] do not react with PhC≡CH, even under more forcing conditions. The complexes [RuH(η⁵-C₉H₇)LL′] (LL′ = dppe; LL′ = dppm; L = L′ = PMe₂Ph; L = PPh₃, L′ = PMe₃; L = PPh₃, L′ = PMe₂Ph) and the indenyl-substituted complexes [RuH(η⁵-Me₃C₉H₄)(CO)(PR ₃)] (PR₃ = PPh₃, PⁱPr₃) react with dimethyl acetylenedicarboxylate to give the alkenyl derivatives [Ru{(E)-C(CO₂Me)=CH(CO₂Me)}(η⁵-C ₉H₇)LL′] and [Ru{(E)-C(CO₂-Me)=CH(CO₂Me)}(η⁵-Me ₃C₉H₄)(CO)(PR₃)], respectively, in diethyl ether under reflux. The reaction of [RuH(η⁵-C₉H₇)LL′] with methyl propiolate yields the α-metalated alkenyl complexes [RU{C(CO₂Me)=CH₂}(η⁵-C₉H ₇)LL′] (LL′ = dppe, dppm; L = L′ = PMe₂Ph; L = PPh₃, L′ = PMe₃) in refluxing diethyl ether. A kinetic study has been carried out for the reaction of the complexes [RuX(η⁵-C₉H₇)(dppm)] with phenylacetylene in toluene, by ¹H and ³¹P(¹H) NMR spectroscopy. The reactions are first order with respect to the ruthenium complex and to the alkyne. The hydride and the deutende complexes react at the same rate; intermediates are not detectable neither by kinetic studies nor by spectroscopy. The activation parameters, from rate measurements in the range 40-60 °C, are as follows:ΔH? = 17 ± 2 kcal mol^-1, ΔS? = -21 ± 4 cal mol^-1 K^-1. An associative mechanism is proposed for the reaction, which involves the formation of an intermediate from the ruthenium complex and the alkyne under rate-determining steady-state conditions, followed by fast hydride migration and product formation. Due to the lack of reactivity of the analogous cyclopentadienyl complex [RuH(η⁵-C₅H₅)(dppm)], the reaction represents a case of indenyl effect. On the other hand, the indenyl and the cyclopentadienyl complexes react at comparable rates with the activated alkyne methyl propiolate.

Full text of DOI:10.1021/om970489d

5470
Organometallics 1997, 16, 5470-5477
In ser tion Rea ction s of Alk yn es in to th e Ru -H Bon d of
In d en ylr u th en iu m (II) Hyd r id e Com p lexes. Mech a n ism
of th e Rea ction of P h en yla cetylen e w ith
[Ru H(η5-C9H7)(d p p m )] (d p p m )
Bis(d ip h en ylp h osp h in o)m eth a n e)
Mauro Bassetti* and Paolo Casellato
Centro CNR di Studio sui Meccanismi di Reazione, c/ o Dipartimento di Chimica,
Universita` “La Sapienza”, 00185 Rome, Italy
M. Pilar Gamasa, J ose´ Gimeno,* Covadonga Gonza´lez-Bernardo, and
Blanca Mart´ın-Vaca
Instituto de Quı´mica Organometa´lica “Enrique Moles” (Unidad Asociada al CSIC),
Departamento de Qu´ımica Orga´nica e Inorga´nica, Facultad de Quı´mica, Universidad
de Oviedo, 33071 Oviedo, Spain
Received J une 10, 1997X
The indenyl complexes [RuX(η5-C9H7)(dppm)] (dppm ) bis(diphenylphosphino)methane,
X ) H, D) react with phenylacetylene to give the products of syn addition [Ru{(E)-
CHdCXPh}(η5-C9H7)(dppm)] in toluene, in the temperature range 40-80 °C. The indenyl
complexes [RuH(η5-C9H7)LL′] (L ) L′ ) PMe2Ph; L ) PPh3, L′ ) PMe2Ph; L ) PPh3, L′ )
PMe3; LL′ ) dppe) and [RuH(η5-Me3C9H4)(CO)(PPh3)] and the cyclopentadienyl complex
[RuH(η5-C5H5)(dppm)] do not react with PhCtCH, even under more forcing conditions. The
complexes [RuH(η5-C9H7)LL′] (LL′ ) dppe; LL′ ) dppm; L ) L′ ) PMe2Ph; L ) PPh3, L′ )
PMe3; L ) PPh3, L′ ) PMe2Ph) and the indenyl-substituted complexes [RuH(η5-
Me3C9H4)(CO)(PR3)] (PR3 ) PPh3, PiPr3) react with dimethyl acetylenedicarboxylate to give
the alkenyl derivatives [Ru{(E)-C(CO2Me)dCH(CO2Me)}(η5-C9H7)LL′] and [Ru{(E)-C(CO2-
Me)dCH(CO2Me)}(η5-Me3C9H4)(CO)(PR3)], respectively, in diethyl ether under reflux. The
reaction of [RuH(η5-C9H7)LL′] with methyl propiolate yields the R-metalated alkenyl
complexes [Ru{C(CO2Me)dCH2}(η5-C9H7)LL′] (LL′ ) dppe, dppm; L ) L′ ) PMe2Ph; L )
PPh3, L′ ) PMe3) in refluxing diethyl ether. A kinetic study has been carried out for the
reaction of the complexes [RuX(η5-C9H7)(dppm)] with phenylacetylene in toluene, by 1H and
31P{1H} NMR spectroscopy. The reactions are first order with respect to the ruthenium
complex and to the alkyne. The hydride and the deuteride complexes react at the same
rate; intermediates are not detectable neither by kinetic studies nor by spectroscopy. The
activation parameters, from rate measurements in the range 40-60 °C, are as follows: ∆Hq
) 17 ( 2 kcal mol-1, ∆Sq ) -21 ( 4 cal mol-1 K-1. An associative mechanism is proposed
for the reaction, which involves the formation of an intermediate from the ruthenium complex
and the alkyne under rate-determining steady-state conditions, followed by fast hydride
migration and product formation. Due to the lack of reactivity of the analogous cyclopen-
tadienyl complex [RuH(η5-C5H5)(dppm)], the reaction represents a case of indenyl effect. On
the other hand, the indenyl and the cyclopentadienyl complexes react at comparable rates
with the activated alkyne methyl propiolate.
In tr od u ction
react with metal hydrides, the outcome of the reaction
is hardly predictable, due to the polyfunctional nature
of both the alkyne and the metal complex. The σ-vinyl
product can react further with the alkyne to give a
variety of organometallic and organic species.3 For
these reasons, the mechanistic features of the simple
addition step (eq 1) to the triple bond have not been
described in depth.
The insertion of acetylenes into metal-hydrogen
bonds represents a key step in many processes of
homogeneous catalysis.1 In this respect, the formation
of σ-vinyl complexes from alkynes and transition-metal
hydrides, which are involved in the reduction of a wide
variety of organic functional groups, has been studied
in detail, in particular with regard to the regio- and
stereochemistry of addition.2 When terminal alkynes
(2) (a) Debad, J . D.; Legzdins, P.; Lumb, S. A.; Batchelor, R. J .;
Einstein, F. W. B. Organometallics 1995, 14, 2543 and references
therein. (b) Herberich, G. E.; Barlage, W.; Linn, K. J . Organomet.
Chem. 1991, 414, 193. (c) van der Zeijden, A. A. H.; Bosch, H. W.;
Berke, H. Organometallics 1992, 11, 563. (d) Torres, M. R.; Santos,
A.; Ros, J .; Solans, X. Organometallics 1987, 6, 1091.
X Abstract published in Advance ACS Abstracts, November 15, 1997.
(1) (a) Otsuka, S.; Nakamura, A. Adv. Organomet. Chem. 1976, 14,
245. (b) Chaloner, P. A.; Esteruelas, M. A.; J oo´, F.; Oro, L. A.
Homogeneous Hydrogenation; Kluwer: Dordrecht, The Netherlands,
1994.
(3) Bianchini, C.; Meli, A.; Peruzzini, M.; Vizza, F.; Frediani, P.
Organometallics 1990, 9, 1146 and references therein.
S0276-7333(97)00489-5 CCC: $14.00 © 1997 American Chemical Society

Reaction of PhCtCH with [RuH(η5-C9H7)(dppm)]
Organometallics, Vol. 16, No. 25, 1997 5471
Exp er im en ta l Section
The reactions were carried out under dry nitrogen using
standard Schlenk techniques. Solvents were dried by standard
methods and distilled under nitrogen before use. Dimethyl
acetylenedicarboxylate, methyl propiolate, and phenylacety-
lene were used as received. The hydrides [RuH(η5-R3C9H4)LL′]
and the deuteride [RuD(η5-C9H7)(Ph2PCD2PPh2)] have been
prepared by following the conventional method.12
Infrared spectra were recorded on a Perkin-Elmer Paragon
1000 spectrometer. The C and H analyses were carried out
with a Perkin-Elmer 240-B microanalyzer (incomplete com-
bustion was observed for complexes 7 and 11). NMR spectra
were recorded on a Bruker AC300 instrument at 300 MHz (1H),
121.5 MHz (31P), or 75.4 MHz (13C) using SiMe4 or 85% H3-
PO4 as standard. The following atom labels have been used
for the 1H and 13C{1H} NMR spectroscopic data:
Continuing our interest in the activation of alkynes,
in this work we report on the reactions of the indenyl
complexes [RuH(η5-C9H7)LL′] (LL′ ) 1,2-bis(diphenyl-
phosphino)ethane (dppe), bis(diphenylphosphino)methane
(dppm); L ) L′ ) PMe2Ph; L ) PPh3, L′ ) PMe3; L )
PPh3, L′ ) PMe2Ph) and [RuH(η5-Me3C9H4)(CO)(PR3)]
(PR3 ) PPh3, PiPr3) with dimethyl acetylenedicarboxy-
late, methyl propiolate, and phenylacetylene to give the
corresponding σ-vinyl derivatives. A mechanistic study
is described for the reaction of [RuX(η5-C9H7)(dppm)] (X
) H, D) and [RuH(η5-C5H5)(dppm)] with phenylacety-
lene and methyl propiolate. We have recently reported
on the reactions of indenylruthenium complexes with
propargylic alcohols, forming very stable allenylidene
complexes.4 The reactions of cyclopentadienylruthe-
nium complexes [RuX(η5-C5H5)(PPh3)2] (X ) H, Me,
CH2Ph) with activated alkynes have been described.5
In particular, the cyclopentadienyl hydride complex
reacts with methyl propiolate or pentafluoropheny-
lacetylene to yield the acetylide complex and products
resulting from interaction of one, two, or three alkyne
molecules. It is also known that ruthenium hydride
complexes are catalysts for the dimerization of alkynes,
which provides a highly attractive route to C4 unsatur-
ated units.6
There is a general interest in studying indenyl (Ind,
C9H7) complexes which exhibit reactivity or stereochem-
ical features different from those of the corresponding
cyclopentadienyl complexes.7 Although it is well-known
that indenyl complexes may react at faster rates in
ligand substitution reactions,8 evidence of higher reac-
tivity for other reactions is still scarce.9 In this respect,
and in the context of this work, rhodium complexes [Rh-
(η5-C9H7)L2] (L ) ethylene, cyclooctene; L2 ) 1,5-
cyclooctadiene) have been described as very efficient
catalysts for the cyclotrimerization of alkynes to benzene
derivatives in comparison with the isostructural cyclo-
pentadienyl complexes.10 A kinetic and mechanistic
investigation of the alkyne insertion reaction in the
iridium complex [IrH(Me)(η5-C9H7)(PMe3)] has revealed
the existence of a low barrier pathway for the coordina-
tion of the alkyne to the metal center.11
1
Selected H, 13C{1H}, and 31P{1H} NMR spectroscopic data for
the complexes 1-11 are collected in Tables 1 and 2.
Syn th esis of [Ru {(E)-C(CO2Me)dCH(CO2Me)}(η5-C9H7)-
LL′] (LL′ ) d p p e (1), d p p m (2); L ) L′ ) P Me2P h (3); L )
P P h 3, L′ ) P Me3 (4); L ) P P h 3, L′ ) P Me2P h (5). A mixture
of [RuH(η5-C9H7)LL′] (0.41 mmol) and MeO2CCtCCO2Me (0.41
mmol) in diethyl ether (50 mL) was heated under reflux. After
the reaction was completed, the solvent was evaporated and
the solid obtained was washed with hexane (2 × 20 mL) and
dried under vacuum. In order to obtain satisfactory elemen-
tary analysis, the products were purified by means of column
chromatography in Florisil. The products were eluted with a
mixture of diethyl ether and ethyl acetate (5/1). In the case
of complex 2, the reaction takes place at room temperature
and the product precipitates in the mixture. 1, LL′ ) d p p e:
reaction time, 2 h; color, yellow; yield, 60%. Anal. Calcd for
RuC41H38O4P2: C, 64.99; H, 5.02. Found: C, 64.55; H, 5.50.
IR (KBr, 2 CO2Me, cm-1): 1697. 1H NMR (δ, ppm): 2.27 and
2.86 (m, 2H each, P(CH2)2P), 4.90 (s, b, 2H, H-1,3), 5.24 (s, b,
1H, H-2), 7.00-7.47 (m, 24H, H-4,5,6,7, PPh2). 13C{1H} NMR
(δ, ppm): 27.50 (m, P(CH2)2P), 50.58 (2CO2Me), 71.45 (C-1,3),
92.75 (C-2), 109.96 (C-3a,7a), 124.30 and 124.93 (C-4,7 and
C-5,6), 127.28-135.67 (m, PPh2), 162.05 (CO2Me), 180.54 (CO2-
Me). 2, LL′ ) d p p m : color, yellow; yield, 70%. Anal. Calcd
for RuC40H36O4P2: C, 64.60; H, 4.80. Found: C, 64.81; H, 4.77.
IR (KBr, 2 CO2Me, cm-1): 1696, 1709. 1H NMR (δ, ppm): 4.57
2
(dt, 1H, J HH ) 13.7 Hz, J HP ) 10.3 Hz, PCHaHbP), 5.13 (dt,
2
(4) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Gonza´lez-Cueva, M.;
Lastra, E.; Borge, J .; Garc´ıa-Granda, S.; Pe´rez-Carren˜o, E. Organo-
metallics 1996, 15, 2137 and references therein.
1H, J HH ) 13.7 Hz, J HP ) 10.3 Hz, PCHaHbP), 5.31 (t, 1H,
J HH ) 2.5 Hz, H-2), 5.44 (d, 2H, J HH ) 2.5 Hz, H-1,3), 7.17-
7.60 (m, 24H, H-4,5,6,7, PPh2). 13C{1H} NMR (δ, ppm): 47.66
(t, J CP ) 21.2 Hz, PCH2P), 49.75 and 49.93 (2CO2Me), 65.05
(C-1,3), 88.33 (C-2), 109.61 (C-3a,7a), 123.89 and 123.98 (C-
4,7 and C-5,6), 126.50-138.80 (m, PPh2), 161.44 (CO2Me),
179.58 (CO2Me). 3, L ) L′ ) P Me2P h : reaction time, 0.5 h;
(5) (a) Bruce, M. I.; Catlow, A.; Humphrey, M. G.; Koutsantonis, G.
A.; Snow, M. R.; Tiekink, E. R. T. J . Organomet. Chem. 1988, 338, 59.
(b) Bruce, M. I.; Gardner, R. C. F.; Howard, J . A. K.; Stone, F. G. A.;
Welling, M.; Woodward, P. J . Chem. Soc., Dalton Trans. 1977, 621.
(6) (a) J ia, G.; Rheingold, A. L.; Meek, D. W. Organometallics 1989,
8, 1378. (b) Kovalev, I. P.; Yevdakov, K. V.; Strelenko, Y. A.; Vinogra-
dov, M. G.; Nikishin, G. I. J . Organomet. Chem. 1990, 386, 139. (c)
Bianchini, C.; Peruzzini, M.; Zanobini, F.; Frediani, P.; Albinati, A. J .
Am. Chem. Soc. 1991, 113, 5453. (d) Wakatsuki, Y.; Yamazaki, H.;
Kumegawa, N.; Satoh, T.; Satoh, J . Y. J . Am. Chem. Soc. 1991, 113,
9604. (e) Yi, C. S.; Liu, N. Organometallics 1996, 15, 3968. (f) Bianchini,
C.; Frediani, P.; Peruzzini, M.; Zanobini, F. Organometallics 1994, 13,
4616 and references therein. (g) Slugovc, C.; Mereiter, K.; Zobetz, E.;
Schmid, R.; Kirchner, K. Organometallics 1996, 15, 5275.
(7) O’Connor, J . M.; Casey, C. P. Chem. Rev. 1987, 87, 307.
(8) (a) Rerek, M. E.; Basolo, F. J . Am. Chem. Soc. 1984, 106, 5908.
(b) Bonifaci, C.; Carta, G.; Ceccon, A.; Gambaro, A.; Santi, S.; Venzo,
A. Organometallics 1996, 15, 1630 and references therein.
(9) (a) Hart-Davis, A. J .; Mawby, R. J . J . Chem. Soc. A 1969, 2403.
(b) Brunner, H.; Fisch, K.; J ones, P. G.; Salbeck, J . Angew. Chem. 1989,
101, 1558. (c) Allevi, M.; Bassetti, M.; Lo Sterzo, C.; Monti, D. J . Chem.
Soc., Dalton Trans. 1996, 3527. (d) Trost, B. M.; Kulawiec, R. J . J .
Am. Chem. Soc. 1993, 115, 2027.
(11) Foo, T.; Bergman, R. G. Organometallics 1992, 11, 1811.
(12) (a) Bruce, M. I.; Humphrey, M. G.; Swincer, A. G.; Wallis, R.
C. Aust. J . Chem. 1984, 37, 1747. (b) Experimental procedure for the
synthesis of [RuH(η5-R3C9H4)LL′]: excess NaOMe (ca. 5:1) was added
to a suspension of [RuX(η5-R3C9H4)LL′] (R ) H, X ) Cl; R ) Me, X )
Br) (1 mmol) in MeOH (100 mL). The mixture was stirred at room
temperature or heated under reflux, depending on the complex. When
the reaction was complete, the solvent was evaporated and the residue
was recrystallized from diethyl ether. The deuteride complex [RuD-
(η5-C9H7)(Ph2PCD2PPh2)] precipitates in the reaction mixture. The
complexes obtained were yellow solids or oils. (c) The complexes have
been characterized by IR, 1H and 31P{1H} NMR spectroscopy, and
elemental analysis (see Supporting Information). The crystal structure
of [RuH(η5-C9H7)(PPh3)2] was determined by X-ray diffraction methods
(Garc´ıa-Granda, S.; Borge, J . Unpublished Results). (d) A subsequent
paper about the protonation of these hydride complexes and the
structural characterization of neutral hydride and cationic dihydride
derivatives is being prepared.
(10) Borrini, A.; Diversi, P.; Ingrosso, G.; Lucherini, A.; Serra, G. J .
Mol. Catal. 1985, 30, 181.

5472 Organometallics, Vol. 16, No. 25, 1997
Ta ble 1. Selected NMR Da ta a for th e Alk en yl Com p lexes 1-7
1Hr
CO2Me
Bassetti et al.
13C{1H}r
compd
31P{1H}
90.93 s
Hâ
CR
Câ
[Ru{(E)-C(CO2Me)dCH(CO2Me)}(η5-C9H7)(dppe)] (1)
2.91 s
3.30 s
3.30 s
3.54 s
3.64 s
4.15 s
3.44 s
3.82 s
3.28 s
3.80 s
3.32 s
3.37 s
3.49 s
3.86 s
3.95 s
184.21 tb
183.53 tc
188.50 te
189.10 vti
186.36 vtm
182.54 dn
183.86 dp
126.50
125.67 td
124.58 tf
j
[Ru{(E)-C(CO2Me)dCH(CO2Me)}(η5-C9H7)(dppm)] (2)
21.43 s
21.79 s
4.48 s
5.88 s
5.00 s
4.81 s
5.87 s
5.97 s
[Ru{(E)-C(CO2Me)dCH(CO2Me)}(η5-C9H7)(PMe2Ph)2] (3)
[Ru{(E)-C(CO2Me)dCH(CO2Me)}(η5-C9H7)(PPh3)(PMe3)] (4)
[Ru{(E)-C(CO2Me)dCH(CO2Me)}(η5-C9H7)(PPh3)(PMe2Ph)] (5)
[Ru{(E)-C(CO2Me)dCH(CO2Me)}(η5-Me3C9H4)(CO)(PPh3)] (6)
[Ru{(E)-C(CO2Me)dCH(CO2Me)}(η5-Me3C9H4)(CO)(PiPr3)] (7)
4.45 dg (PMe3)
57.90 dh
16.95 dk (PMe2Ph)
j
58.54 dl
51.65 s
124.47 do
124.34 dq
55.37 s
a
b 2
c 2
δ in ppm. Abbreviations: s, singlet; d, doublet; t, triplet; m, multiplet. Spectra recorded in C6D6.
J
) 13.3 Hz.
J
) 13.0 Hz.
CP
CP
3J CP ) 4.2 Hz.
aromatic signals.
J
) 14.4 Hz.
) 33.3 Hz.
J
) 6.8 Hz.
J
) 33.9 Hz. J PP ) 33.9 Hz.
J )
CP
2J C′P′ ) 14.2 Hz. Signal overlapped by
d
e 2
f 3
g 2
h
2
i 2
j
CP
CP
PP
k 2
l 2
m
2
n
2
o 3
p 2
q 3
J
J
) 33.3 Hz. 2J CP ) J C′P′ ) 14.9 Hz. J CP ) 11.7 Hz.
J
) 4.5 Hz.
J
) 12.0 Hz.
J
CP
PP
PP
CP
CP
) 4.5 Hz. The following atom labels are used for the 1H and 13C{1H} NMR spectroscopic data:
r
Ta ble 2. Selected NMR Da ta a for Com p lexes 8-11
1Hh
13C{1H}h
compd
31P{1H}
94.45 s
CO2Me
3.04 s
dCH2
CR
Câ
[Ru{C(CO2Me)dCH2}(η5-C9H7)(dppe)] (8)
4.23 s, b
5.99 s, b
4.13 s, b
5.34 s, b
5.03 s
6.39 s, b
5.27 s, b
6.48 s, b
152.30 tb
152.57 m
157.65 td
153.60 m
c
c
[Ru{C(CO2Me)dCH2}(η5-C9H7)(dppm)] (9)
[Ru{C(CO2Me)dCH2}(η5-C9H7)(PMe2Ph)2] (10)
[Ru{C(CO2Me)dCH2}(η5-C9H7)(PPh3)(PMe3)] (11)
21.50 s
23.08 s
2.93 s
3.81 s
3.56 s
126.13 te
5.14 df (PMe3)
57.25 dg
c
a
b 2
δ in ppm. Abbreviations: s, singlet; d, doublet; t, triplet; m, multiplet; b, broad signal. Spectra recorded in C6D6.
J
) 14.6 Hz.
CP
c Signal overlapped by aromatic signals. J CP ) 15.9 Hz.
J
) 5.4 Hz.
J
) 33.8 Hz.
J
) 33.8 Hz. The following atom labels
PP
d
2
e 3
f 2
g 2
h
CP
PP
are used for the 1H and 13C{1H} spectroscopic data:
color, yellow; yield, 70%. Anal. Calcd for RuC31H36O4P2: C,
58.57; H, 5.71. Found: C, 58.87; H, 5.65. IR (KBr, 2 CO2Me,
23H, H-4,5,6,7, Ph, PPh3). 13C{1H} NMR (δ, ppm): 17.93 (d,
J CP ) 27.0 Hz, PMea), 20.50 (d, J CP ) 29.7 Hz, PMeb), 49.89
2
2
cm-1): 1700, 1742. 1H NMR (δ, ppm): 1.49 (vt, 6H, | J HP
+
and 50.54 (2CO2Me), 72.85 (d, J CP ) 7.5 Hz), and 74.47 (d,
4J HP′| ) 8.3 Hz, PMea, PMea′), 1.67 (vt, 6H, | J HP + 4J HP′| ) 7.8
Hz, PMeb, PMeb′), 5.10 (d, 2H, J HH ) 2.5 Hz, H-1,3), 5.94 (t,
1H, J HH ) 2.5 Hz, H-2), 7.01-7.26 (m, 14H, H-4,5,6,7, PPh).
2J CP ) 7.5 Hz) (C-1,3), 98.68 (C-2), 111.71 (m, C-3a,7a), 122.62,
123.90, 124.70, and 126.05 (C-4,5,6,7), 127.13-143.07 (m, Ph,
PPh3), 162.26 (CO2Me), 181.00 (CO2Me).
2
13C{1H} NMR (δ, ppm): 17.60 (vt, |J CP
+
3J CP′| ) 30.1 Hz,
Syn t h esis of [R u {(E)-C(CO2Me)dCH (CO2Me)}(η5-
Me3C9H4)(CO)(P R3)] (P R3 ) P P h 3 (6), P iP r 3 (7)). A mixture
of [RuH(η5-Me3C9H4)(CO)(PR3)] (0.5 mmol) and MeO2CCtCCO2-
Me (2.5 mmol) in diethyl ether (75 mL) was heated under
reflux. After the reaction was completed, the solvent was
evaporated and the products were purified by means of column
chromatography in Florisil. The products were eluted with a
mixture of diethyl ether and ethyl acetate (5/1). In the case
of complex 7, toluene is used instead of diethyl ether, the
reaction takes place at 65 °C, and the product obtained is an
oil. 6, P R3 ) P P h 3: reaction time, 2 h 45 min; color, yellow;
yield, 50%. Anal. Calcd for RuC37H35O5P: C, 64.25; H, 5.10.
Found: C, 63.32; H, 4.77. IR (CH2Cl2, CO, cm-1): 1924. IR
(KBr, 2 CO2Me, cm-1): 1703, 1740. 1H NMR (δ, ppm): 1.42
PMea, PMea′), 19.70 (vt, |J CP + 3J CP′| ) 28.2 Hz, PMeb, PMeb′),
2
2
49.60 and 50.08 (2CO2Me), 72.09 (vt, J CP ) J C′P′ ) 3.5 Hz,
C-1,3), 96.90 (C-2), 109.76 (C-3a,7a), 123.63 and 124.21 (C-
4,7 and C-5,6), 124.44-141.34 (m, PPh), 161.51 (CO2Me),
179.70 (CO2Me). 4, L ) P P h 3, L′ ) P Me3: reaction time, 1 h;
color, yellow; yield, 75%. Anal. Calcd for RuC36H38O4P2: C,
61.97; H, 5.50. Found: C, 60.98; H, 5.77. IR (KBr, 2 CO2Me,
cm-1): 1699. 1H NMR (δ, ppm): 1.10 (d, 9H, J HP ) 8.9 Hz,
2
PMe3), 4.59, 4.86, and 5.34 (s, b, 1H each, H-1,2,3), 5.97, 6.76,
and 6.90 (m, 1H each, H-4,5,6,7), 7.01-7.30 (m, 16H, H-4,5,6,7,
PPh3). 13C{1H} NMR (δ, ppm): 21.00 (d, J CP ) 28.1 Hz, PMe3),
2
50.71 and 51.10 (2CO2Me), 71.78 (d, J CP ) 8.0 Hz) and 73.63
2
(d, J CP ) 8.3 Hz) (C-1,3), 99.56 (C-2), 107.71 and 111.34 (C-
4
4
3a,7a), 124.05, 124.11, 124.92, and 125.82 (C-4,5,6,7), 126.08-
137.30 (m, PPh3), 162.44 (CO2Me), 181.25 (CO2Me). 5, L )
P P h 3, L′ ) P Me2P h : reaction time, 1 h; color, yellow; yield,
65%. Anal. Calcd for RuC41H40O4P2: C: 64.81; H: 5.30.
Found: C, 63.62; H, 5.31. IR (KBr, 2 CO2Me, cm-1): 1684,
(d, 3H, J PH ) 1.5 Hz), 1.85 (d, 3H, J PH ) 1.0 Hz), and 2.13
(d, 3H, 4J PH ) 2.5 Hz) (Me3C9H4), 6.52-7.55 (m, 19H, H-4,5,6,7,
PPh3). 13C{1H} NMR (δ, ppm): 7.94, 9.42, and 10.77 (Me3C9H4),
2
50.26 and 50.44 (2CO2Me), 83.22 and 84.53 (d, J CP ) 7.2 Hz)
(C-1,3), 105.39, 110.32, and 116.27 (C-2,3a,7a), 120.84, 122.73,
2
1705. 1H NMR (δ, ppm): 1.44 (d, 3H, J HP ) 8.9 Hz, PMea),
124.72 and 126.72 (C-4,5,6,7), 127.71-134.51 (m, PPh3), 161.94
2
2
1.73 (d, 3H, J HP ) 8.7 Hz, PMeb), 4.51, 4.84, and 5.45 (s, b,
(CO2Me), 177.67 (CO2Me), 207.46 (d, J CP ) 17.1 Hz, CO). 7,
1H each, H-1,2,3), 5.70 (m, 1H, H-4,5,6 or 7), 6.30-7.30 (m,
P R3 ) P iP r 3: reaction time, 1 h 45 min; color, yellow. IR (CH2-

Reaction of PhCtCH with [RuH(η5-C9H7)(dppm)]
Organometallics, Vol. 16, No. 25, 1997 5473
Cl2, CO, cm-1): 1925. IR (KBr, 2 CO2Me, cm-1): 1697. 1H
Sch em e 1. In ser tion of Dim eth yl
NMR (δ, ppm): 0.75-0.93 (m, 18H, P([CH(CH3)2]3), 1.83-1.94
Acetylen ed ica r boxyla te in th e Ru -H Bon d
4
(m, 3H, P([CH(CH3)2]3), 1.81 (s, 3H), 2.01 (d, 3H, J PH ) 1.2
4
Hz) and 2.04 (d, 3H, J PH ) 1.2 Hz) (Me3C9H4), 6.80-7.16 (m,
4H, H-4,5,6,7). 13C{1H} NMR (δ, ppm): 10.68 (Me-1,3), 11.48
(Me-2), 20.15 and 20.49 (3Me each, P([CH(CH3)2]3), 28.13 (d,
2J CP ) 20.7 Hz, P([CH(CH3)2]3), 51.03 and 51.07 (2CO2Me),
82.74 (d, 2J CP ) 3.3 Hz) and 84.15 (C-1,3), 109.41, 111.78, and
114.48 (C-2,3a,7a), 122.86, 122.99, 125.14, and 125.40 (C-
2
4,5,6,7), 162.45 (CO2Me), 178.98 (CO2Me), 211.14 (d, J CP
17.4 Hz, CO).
)
Syn th esis of [Ru {C(CO2Me)dCH2}(η5-C9H7)LL′] (LL′ )
d p p e (8), d p p m (9); L ) L′ ) P Me2P h (10); L ) P P h 3, L′ )
P Me3 (11). A mixture of [RuH(η5-C9H7)LL′] (0.41 mmol) and
HCtCCO2Me (1.25 mmol) in diethyl ether (50 mL) was heated
under reflux. After the reaction was completed, the solvent
was evaporated and the products were purified by means of
column chromatography in Florisil. The products were eluted
with a mixture of diethyl ether and ethyl acetate (5/1). 8, LL′
) d p p e: reaction time, 3 h; color, brown; yield, 70%. Anal.
Calcd for RuC39H36O2P2: C, 66.95; H, 5.15. Found: C, 66.78;
H, 5.41. IR (KBr, CO2Me, cm-1): 1697. 1H NMR (δ, ppm):
2.18 and 2.90 (m, 2H each, P(CH2)2P), 5.06 (d, 2H, J HH ) 2.4
Hz, H-1,3), 5.51 (t, 1H, J HH ) 2.4 Hz, H-2), 7.07-7.87 (m, 24H,
H-4,5,6,7, PPh2). 13C{1H} NMR (δ, ppm): 27.41 (m, P(CH2)2P),
3
PPh2, H-4,7 or H-5,6), 7.64 (dt, 1H, J HH ) 16.4 Hz, J HP ) 5.0
Hz, HR). 13C{1H} NMR (δ, ppm): 49.29 (t, J CP ) 21.1 Hz,
2
50.48 (CO2Me), 71.52 (vt, J CP ) 2J C′P′ ) 1.5 Hz, C-1,3), 93.04
2
2
2
2
PCH2P), 68.63 (vt, J CP ) J C′P′ ) 3.3 Hz, C-1,3), 90.68 (C-2),
(C-2), 109.60 (vt, J CP ) J C′P′ ) 1.8 Hz, C-3a,7a), 124.30 and
124.45 (C-4,7 and C-5,6), 128.00-143.31 (m, PPh2), 181.20
(CO2Me). 9, LL′ ) d p p m : reaction time, 1 h; color, orange;
yield, 80%. Anal. Calcd for RuC38H34O2P2: C, 66.57; H, 4.96.
Found: C, 65.82; H, 4.87. IR (KBr, CO2Me, cm-1): 1691. 1H
NMR (δ, ppm): 4.56 (m, 1H, PCHaHbP), 4.80 (m, 1H, PCHaH-
bP), 5.34 (s, b, 1H, H-2), 5.45 (s, b, 2H, H-1,3), 7.06-7.51 (m,
24H, H-4,5,6,7, PPh2). 13C{1H} NMR (δ, ppm): 48.70 (m,
PCH2P), 50.42 (CO2Me), 68.09 (C-1,3), 89.28 (C-2), 110.10 (C-
3a,7a), 123.97 and 124.72 (C-4,7 and C-5,6), 125.09-135.58
(m, PPh2), 181.06 (CO2Me). 10, L ) L′ ) P Me2P h : reaction
2
2
108.63 (t, J CP ) J C′P′ ) 2.0 Hz, C-3a,7a), 122.98 and 124.33
(C-4,7 and C-5,6), 127.90-140.08 (m, Ph, PPh2), 140.33 (t, 3J CP
2
) 5.0 Hz, Câ), 151.27 (t, J CP ) 15.3 Hz, Ru-CR).
Kin etic Mea su r em en ts. Toluene was distilled over potas-
sium/benzophenone; phenylacetylene was distilled under ar-
gon. Kinetic experiments were carried out under pseudo-first-
order conditions, using a large excess of the alkyne, and
followed by NMR spectroscopy. The alkyne (24-60 µL) was
added by syringe in a 5 mm NMR tube to solutions of the
ruthenium complex (6-20 mg) in 700 µL of toluene-d8 (1H
NMR) or 500 µL of toluene and 200 µL of toluene-d8 (31P NMR)
using 1,3,5 tri-tert-butylbenzene (0.1-0.2 mg), triphenylphos-
phine, or tri-o-tolylphosphine (6-10 mg) as internal standard,
respectively. The tube was kept in the NMR probe and
thermostated at the appropriate temperature ((1 °C) through-
out all the experiment. The rate of disappearance of the
hydride complex was followed by integration of the Ru-H
resonance or the phosphorus resonance versus the correspond-
time, 2 h; color, yellow; yield, 80%. Anal. Calcd for RuC29
-
H
34O2P2: C, 60.30; H, 5.93. Found: C, 59.38; H, 5.89. IR
(KBr, CO2Me, cm-1): 1681. 1H NMR (δ, ppm): 1.62 (vt, 6H,
2
2
| J HP
+
4J HP′| ) 9.9 Hz, PMea, PMea′), 1.73 (vt, 6H, | J HP
+
4J HP′| ) 8.0 Hz, PMeb, PMeb′), 5.18 (d, 2H, J HH ) 2.5 Hz, H-1,3),
5.91 (t, 1H, J HH ) 2.5 Hz, H-2), 7.05 (m, 2H, H-4,7 or H-5,6),
7.18-7.26 (m, 12H, PPh, H-4,7 or H-5,6). 13C{1H} NMR (δ,
3
ppm): 20.42 (vt, |J CP + J CP′| ) 29.3 Hz, PMea, PMea′), 22.84
(vt, |J CP + 3J CP′| ) 28.1 Hz, PMeb, PMeb′), 51.92 (CO2Me), 73.30
ing internal standards. Pseudo-first-order rate constants (kobs
)
2
2
were obtained by exponential fitting of the ratio of the
integrated resonances vs time, using a nonlinear least-squares
regression program. Duplications of single kinetic runs were
(vt, J CP ) J C′P′ ) 3.7 Hz, C-1,3), 98.59 (C-2), 111.69 (C-3a,
C-7a), 125.79 (C-4,5,6,7), 130.61-144.54 (m, PPh, C-4,5,6,7),
182.53 (CO2Me). 11, L ) P P h 3, L′ ) P Me3: reaction time,
1.5 h; color, yellow; yield, 70%. Anal. Calcd for
RuC34H36O2P2: C, 63.85; H, 5.63. Found: C, 62.53; H, 5.63.
IR (KBr, CO2Me, cm-1): 1698. 1H NMR (δ, ppm): 1.09 (d,
9H, 2J HP ) 8.3 Hz, PMe3), 5.10 (s, b, 2H, H-1,3), 5.77 (s, b, 1H,
H-2), 6.74 (m, 1H, H-4,5,6 or 7), 7.16-7.91 (m, 18H, H-4,5,6,7,
PPh3). 13C{1H} NMR (δ, ppm): 20.45 (d, J CP ) 27.4 Hz, PMe3),
1
reproducible to within 12%. Measurements by H NMR were
in agreement with those by 31P NMR. Activation parameters
were obtained by linear least-squares analysis of the depen-
dence of ln(k2/T) on 1/T. Blank experiments on solutions of
the ruthenium complex in the absence of phenylacetylene
showed no significant decomposition during the time required
for the kinetic runs.
2
2
50.32 (CO2Me), 70.28 (d, J CP ) 7.8 Hz) and 71.08 (d, J CP
)
7.0 Hz) (C-1,3), 98.98 (C-2), 106.88 and 109.86 (C-3a,7a),
122.63, 123.04, 123.20 and 124.45 (C-4,5,6,7), 127.08-138.69
(m, PPh3), 180.46 (CO2Me).
Resu lts
Syn th esis of [Ru {(E)-CHdCHP h }(η5-C9H7)(d p p m )] (12).
A mixture of [RuH(η5-C9H7)(dppm)] (0.41 mmol) and HCtCPh
(0.41 mmol) in toluene (30 mL) was heated at 80 °C for 3 h,
the color of the solution changing from yellow to dark orange.
The solvent was evaporated, and the product obtained was
washed with hexane (2 × 10 mL) and dried under vacuum:
reaction time, 3 h; color, orange; yield, 70%. Anal. Calcd for
Rea ction s w ith Activa ted Alk yn es. Complexes of
the type [RuH(η5-C9H7)LL′] and [RuH(η5-Me3C9H4)(CO)-
(L′)] react with an equimolar amount of dimethyl
acetylenedicarboxylate in refluxing diethyl ether to give
the (E)-alkenyl complexes 1-7 (50-75% yield) (Scheme
1). However, no reaction occurs for the complex [RuH-
(η5-C9H7)(PPh3)(PMePh2)].
Complexes 1-7 have been isolated as yellow air-
stable solids. IR spectra show one or two ν(CdO)
absorptions in the range 1684-1742 cm-1, typical of
uncoordinated CO2Me groups.2c Selected NMR data are
reported in Table 1. 31P{1H} NMR spectra displaying
1
RuC42H36P2: C, 71.70; H, 5.12. Found: C, 71.61; H, 5.14. H
2
NMR (δ, ppm): 3.92 (dt, 1H, J HH ) 13.7 Hz, J HP ) 11.2 Hz,
2
PCHaHbP), 4.53 (dt, 1H, J HH ) 13.7 Hz, J HP ) 9.8 Hz,
PCHaHbP), 5.16 (t, 1H, J HH ) 2.6 Hz, H-2), 5.35 (d, 2H, J HH
)
2.6 Hz, H-1,3), 5.38 (d, 1H, J HH ) 16.4 Hz, Hâ), 6.35-6.91 (m,
5H, dCPh), 7.01 (m, 2H, H-4,7 or H-5,6), 7.10-7.50 (m, 22H,

5474 Organometallics, Vol. 16, No. 25, 1997
Bassetti et al.
Sch em e 2. In ser tion of Meth yl P r op iola te in th e
Sch em e 3. In ser tion of P h en yla cetylen e in th e
Ru -H Bon d
Ru -H Bon d
13C{1H} and 1H NMR spectra for complex 12 show
typical alkenyl resonances in the E configuration.
Proton resonances at δ 5.38 (d) and 7.64 (dt, 3J HP ) 5.0
Hz) ppm show a large proton coupling constant (J ΗΗ
)
16.4 Hz), in agreement with the mutually trans ar-
rangement. The R-alkenyl proton is also coupled to the
equivalent phosphorus atoms of dppm (δ 22.59 ppm).
The regioselectivity of the insertion process is confirmed
by the reactions of deuterated species. The ruthenium
deuteride complex [RuD(η5-C9H7)(Ph2PCD2PPh2)] reacts
with PhCtCH to give [Ru{(E)-CHdCDPh}(η5-C9H7)(Ph2-
singlet resonances (complexes 1-3, 6, and 7) and the
expected AX pattern (complexes 4 and 5) are in agree-
ment with the proposed structures. 13C{1H} and 1H
NMR spectra show carbon and proton resonances of the
alkenyl group which can be compared to those of similar
(E)-alkenyl ruthenium(II) complexes formed in analo-
gous insertion reactions with dimethyl acetylenedicar-
boxylate. In particular, the 13C NMR spectrum of
complex 5 shows that the coupling constant (3J CH) for
Hâ and the carbon atom of the carboxylate group in the
trans position (on the CR atom) is 13.8 Hz. Similar
3
PCD2PPh2)] (1H NMR: t, δ 7.88 ppm, J HP ) 5.4 Hz,
RuCHd). The reaction of [RuH(η5-C9H7)(dppm)] with
phenylacetylene-d affords the complex [Ru{(E)-CDd
CHPh}(η5-C9H7)(dppm)] (1H NMR: s, δ 5.70 ppm,
dCHPh, toluene-d8), as indicated by the disappearance
of the double triplet of RuCHd observed in 12 at 7.86
ppm (toluene-d8).
values are characteristic for other E isomers (3J CH
)
14-16 Hz), while significantly lower values correspond
to Z isomers (3J CH ) 8.5-10 Hz).5a,13 Characteristic
resonances of these complexes are (i) a singlet in the
range δ 3.95-5.97 ppm of the alkenyl proton (ii) a triplet
in the range δ 183.53-189.1 ppm (2J CP ) 12.4-14.9 Hz)
of the alkenyl CR atom, and (iii) a singlet or triplet signal
in the range δ 124.58-126.5 ppm of the Câ atom.
The terminal alkyne methyl propiolate reacts with the
indenyl complexes [RuH(η5-C9H7)LL′] (LL′ ) dppm,
dppe; L ) L′ ) PMe2Ph; L ) PPh3, L′ ) PMe3) to give
vinyl complexes 8-11 (70-80% yield) (Scheme 2).
However, no insertion product is obtained when the
complexes [RuH(η5-C9H7)(PPh3)(PMe2Ph)] and [RuH(η5-
Me3C9H4)(CO)(PR3)] (PR3 ) PPh3, PiPr3) are used.
Spectroscopic data for complexes 8-11 are reported
in Table 2. 1H NMR spectra show two unresolved
multiplets at δ 4.13-5.27 and 5.99-6.48 ppm assigned
to the unequivalent vinyl protons. The relatively small
J HH indicates the cis (geminal) arrangement consistent
with an R-metalation insertion. Characteristic signals
in the 13C{1H} NMR spectra (δ 152.3-157.65 ppm, t,
When the reaction is carried out in the presence of
excess phenylacetylene, the alkenyl complex 12 is
formed as the major product, along with traces of the
alkynyl complex [Ru(CtCPh)(η5-C9H7)(dppm)], as ob-
served by FT-IR spectroscopy (2085 cm-1, toluene), and
traces of styrene. Consistent formation of the coupling
products of phenylacetylene, as a mixture of trans and
cis isomers of PhCtCCHdCHPh, occurs during 4-5
days (50 °C) and is accompanied by decomposition of
all organometallic species, as a black precipitate. The
reaction is moderately catalytic, since 4 mol of enynes/
mol of hydride complex is obtained. Studies to deter-
mine the reaction conditions and efficiency of the
catalytic dimerization of alkynes by indenylruthenium
complexes are in progress.15 This process has been
described for other ruthenium complexes as well.6
The effect of structural features on the insertion
reaction has been exploited in a variety of complexes
having different ancillary ligands. In contrast to the
reactivity of the complex [RuH(η5-C9H7)(dppm)], the
analogous complexes [RuH(η5-C9H7)LL′] (L ) L′ ) PMe2-
Ph; L ) PPh3, L′ ) PMe2Ph; L ) PPh3, L′ ) PMe3; LL′
) dppe), [RuH(η5-Me3C9H4)(CO)(PPh3)] and the cyclo-
pentadienyl complex [RuH(η5-C5H5)(dppm)] do not react
with PhCtCH, neither under stoichiometric conditions
nor with excess alkyne, after several days in toluene at
80 °C.
J CP ) 15.5 Hz, Ru-C CO2Me, and 122.73 ppm, t, J CP
)
1.4 Hz, dCH2) are also in agreement with this alkenyl
configuration. Similar vinyl groups have also been
generated from insertion reactions of methyl propiolate
in ruthenium(II) and osmium(II) hydride complexes.14
Rea ction s w ith P h en yla cetylen e. The reaction of
an equimolar mixture of the complex [RuH(η5-C9H7)-
(dppm)] and phenylacetylene in toluene at 80 °C leads
to an orange solution from which the styryl complex [Ru-
{(E)-CHdCHPh}(η5-C9H7)(dppm)] (12) is obtained as a
yellow-orange air-stable solid (Scheme 3).
Kin etics. A kinetic study for the reaction between
[RuH(η5-C9H7)(dppm)] and phenylacetylene has been
carried out using 1H and 31P NMR spectroscopy, in
solutions of toluene-d8. Phenylacetylene has been used
in large excess, in the concentration range 0.26-0.72
M with respect to the ruthenium complex, 0.04-0.01
M, in order to ensure pseudo-first-order conditions. 1H
NMR allows us to detect the disappearance of the
hydride signal, as a triplet of doublets at -13.5 ppm,
(13) (a) Herberich, G. E.; Barlage, W. Organometallics 1987, 6, 1924.
(b) Vessy, J . D.; Mawby, R. J . J . Chem. Soc., Dalton Trans. 1993, 51.
(14) (a) Werner, H.; Meyer, U.; Peters, K; von Schnering, H. G.
Chem. Ber. 1989, 122, 2097. (b) Esteruelas, M. A.; Lahoz, F. J .; Lo´pez,
J . A.; Oro, L. A.; Schulu¨nken, C.; Valero, C.; Werner, H. Organome-
tallics 1992, 11, 2034.
(15) Gimeno, J ; Bassetti, M. Unpublished results.

Reaction of PhCtCH with [RuH(η5-C9H7)(dppm)]
Organometallics, Vol. 16, No. 25, 1997 5475
F igu r e 1. Plot of 31P NMR integrals (I/Istand)) versus time
for the disappearance of the complex [RuH(η5-C9H7)(dppm)]
and for the formation of the complex [Ru{(E)-CHdCHPh}-
(η5-C9H7)(dppm)], in the reaction with phenylacetylene
(0.719 M, 50 °C) in toluene/toluene-d8. [Ru] ) Ru(η5-C9H7)-
(dppm).
F igu r e 2. Plot of kobs vs phenylacetylene concentration for
the reaction of [RuH(η5-C9H7)(dppm)] in toluene, at 50 °C.
Ta ble 4. Obser ved Ra te Con sta n ts, kobs, for th e
Rea ction of [Ru D(η5-C9H7)(P h 2P CD2P P h 2)] w ith
P h en yla cetylen e in Tolu en e, a t 50 °Ca ,b
c
d
[PhCtCH], (M)
kobs (s-1
)
kobs (s-1
)
Ta ble 3. Obser ved Ra te Con sta n ts, kobs, for th e
Rea ction of [Ru H(η5-C9H7)(d p p m )] w ith
P h en yla cetylen e in Tolu en e, a t 50 °Ca
0.265
0.504
0.503
1.1 × 10-4
2.7 × 10-4
2.4 × 10-4
2.2 × 10-4 e
[PhCtCH],
kobs
)
kobs
)
k1
[RuD(η5-C9H7)(Ph2PCD2PPh2)] ) 0.020-0.025 M. b 31P{1H}
a
c,d
d,e
T (°C)
(M)
methodb
(s-1
(s-1
(M-1 s-1
)
N MR. (-d[Ru D(η5-C9H 7)(P h 2P CD2P P h 2)]/dt). d[Ru {(E )-
CHdCDPh}(η5-C9H7)(Ph2PCD2PPh2)]/dt. e 1H NMR (t, J HH ) 2.7
Hz, indenyl H-2).
c
d
50
50
50
40
50
60
50
0.265
0.265
0.386
0.504
0.504
0.504
0.719
31P{1H} 9.7 × 10-5 1.2 × 10-4
1H
1.3 × 10-4
31P{1H} 1.5 × 10-4
31P{1H} 9.2 × 10-5
31P{1H} 2.0 × 10-4
31P{1H} 5.3 × 10-4
31P{1H} 3.2 × 10-4
1.8 × 10-4
4.0 × 10-4
1.1 × 10-3
( 4 cal mol-1 K-1, respectively. The kinetics for the
reaction of the deuteride complex [RuD(η5-C9H7)(PPh2-
CD2PPh2)] with phenylacetylene have been obtained by
following the disappearance of the phosphorus peak at
18.12 ppm with time by 31P NMR or the appearance of
the product [Ru{(E)-CHdCDPh}(η5-C9H7)(PPh2CD2-
PPh2)] by 1H NMR spectroscopy. The values of the
observed rate constants are reported in Table 4.
[RuH(η5-C9H7)(dppm)] ) 0.01-0.04 M. Internal integration
a
b
standards are tris-tert-butylbenzene for 1H NMR and P(o-tolyl)3
for 31P{1H} NMR spectroscopy. c -d[RuH(η5-C9H7)(dppm)]/dt. All
d
values (12%. e (d[12]/dt).
and the appearance of the doublet of the vinylic product
at 5.75 ppm (J HH ) 16.3 Hz). The presence of the
starting material and that of the product are conve-
niently followed with time by 31P NMR (δ 18.65 and
20.84 ppm, respectively). The latter method allows
more precise integration of the resonances with respect
to the internal standard triphenylphosphine or tri-o-
tolylphosphine and has therefore been used in most
experiments. The reactions are cleanly first order with
respect to the hydride complex for 3-4 half-lives.
Figure 1 shows a plot of integrals vs time for both the
disappearance of the hydride complex [RuH(η5-C9H7)-
(dppm)] and the formation of the alkenyl complex 12.
Observed rate constants, kobs (s-1), obtained at dif-
ferent concentrations of PhCtCH and temperatures are
reported in Table 3. Figure 2 shows a plot of kobs vs
the concentration of phenylacetylene for the disappear-
ance of the hydride complex.
The reactions of the indenyl and cyclopentadienyl
complexes [RuH(η5-L)(dppm)] (L ) C5H5, C9H7) with
methyl propiolate have been followed by 31P{1H} NMR,
in toluene at 40 °C. The two complexes react at similar
rates ([RuH(η5-C5H5)(dppm)], kobs ) 7.8 × 10-4 s-1
,
[HCtCCO2Me] ) 0.48 M; [RuH(η5-C9H7)(dppm)], kobs
) 6.8 × 10-4 s-1, [HCtCCO2Me] ) 0.24 M).
Discu ssion
Rea ction s. The reaction of the ruthenium(II) hy-
dride complex [RuH(η5-C9H7)(dppm)] with phenylacety-
lene proceeds smoothly in toluene to form essentially
the product of insertion, [Ru{(E)-CHdCHPh}(η5-C9H7)-
(dppm)] (Scheme 3). The reactions with deuterium-
labeled species, [RuD(η5-C9H7)(Ph2PCD2PPh2)] or
PhCtCD, confirm that the insertion is regio- and
stereoselective and proceeds in a cis fashion, as has been
found in a number of reactions of phenylacetylene with
the ruthenium hydride complexes.14a,16
The alkynes bearing electron-withdrawing substitu-
ents react readily with the indenylruthenium(II) hy-
dride complexes to give the expected alkenyl derivatives.
Thus, complexes 1-7 are obtained from the cis insertion
of the symmetric dimethyl acetylenedicarboxylate, while
the reactions with the asymmetric alkyne methyl pro-
piolate yield the R-metalated complexes 8-11. The
The linear dependence on [PhCtCH] indicates that
the reaction is first order in the alkyne as well, therefore
second order overall, and that intermediates are not
kinetically detectable (eq 2).
kobs ) k1[PhCtCH]
(2)
The second-order rate constants k1 (M-1 s-1), are
reported in Table 3. The enthalpy and the entropy of
activation, calculated from the experiments in the range
40-60 °C, are ∆Hq ) 17 ( 2 kcal mol-1 and ∆Sq ) -21
(16) Torres, M. R.; Vagas, A.; Santos, A.; Ros, J . J . Organomet.
Chem. 1986, 309, 169.

5476 Organometallics, Vol. 16, No. 25, 1997
Bassetti et al.
Ch a r t 1
stereo- and regiochemistry of these reactions can be
compared with that reported for analogous ruthenium-
(II) and osmium(II) alkenyl complexes. The complex
[Ru{(Z)-MeO2CCdC(H)CO2Me}(η5-C5H5)(PPh3)2] is
formed from the isomerization of the corresponding E
stereoisomer.5a â-Metalation-type insertions have been
reported in the reactions of 16e- complexes [MHCl(CO)-
(PR3)2] (M ) Ru, Os)14a and [OsHCl(CO)2(OCMe2)(Pi-
Pr3)2]14b with HCtCCO2Me. It is worth noting the
steric influence of the ancillary phosphine ligands. In
contrast to the reactivity of [RuH(η5-C9H7)(PMe2Ph)2],
which yields the vinyl complex 10, the insertion reaction
with methyl propiolate does not proceed for the com-
plexes [RuH(η5-C9H7)(PMe2Ph)(PPh3)] and [RuH(η5-
Me3C9H4)(CO)(PR3)] (PR3 ) PPh3, PiPr3).
Kin etics. The relevant results of the kinetic study
for the reaction of [RuH(η5-C9H7)(dppm)] with pheny-
lacetylene are the following: first-order dependence on
both hydride complex and alkyne, negative entropy of
activation, absence of primary kinetic isotopic effect,
intermediates not observable by either spectroscopic or
kinetic means, and indenyl effect. This picture is
indicative of an associative process, in which both the
hydride complex and phenylacetylene participate in the
rate-limiting step. The lack of isotopic effect suggests
that the overall transformation from hydride to vinyl
complex is not a single concerted process and that
breaking of the Ru-H bond occurs rapidly after the
rate-limiting step. An associative mechanism consistent
with the experiments is represented in Scheme 4. The
as a bridging system for bimetallic complexes rather
than to act as a chelating ligand for monometallic
species is well-known.17 Monodentate dppm complexes
generated from precursors in which chelating dppm is
acting as a chelate ligand have been reported.18 Ex-
change of the indenyl ligand for the cyclopentadienyl
ring also completely inhibits the process. Therefore, this
reaction represents another case of the indenyl effect,
in a process different from the classical cases of ligand
substitution reactions.7,8 However, the effect vanishes
in the reaction with the activated alkyne methyl pro-
piolate. In fact, by taking into consideration the dif-
ferent concentrations of alkyne in the two experiments
(kobs/[HCtCCO2Me]), the indenyl complex appears less
than twice as reactive as the cyclopentadienyl analogue.
A relevant precedent for indenyl effect in reactions of
alkynes has been described for the trimerization process
catalyzed by indenylrhodium complexes.10
Analogous experimental features, e.g. linear depen-
dence on alkyne concentration, negative entropy of
activation, and lack of kinetic isotopic effect, were
observed by Bergman and Foo for the insertion reaction
of the iridium complex [IrH(Me)(η5-C9H7)(PMe3)] with
tert-butylacetylene, and the data were interpreted ac-
cording to the same kinetic analysis shown in Scheme
4 and eq 3.11 Reaction rates of the iridium complex (e.g.
second-order rate constant: 1.1 × 10-4 M-1 s-1 at 35
°C) and of the ruthenium complex of this study are also
similar. Although a direct rate comparison with an
analogous iridium cyclopentadienyl complex is not
available, the importance of ring-slipped pathways was
proposed to explain the facile insertion process. In fact,
the role of the indenyl ligand in providing low-energy
pathways through changes of hapticity is well-docu-
mented for the two metals of group 9, rhodium8,10 and
iridium.19
With regard to the structure of the intermediate
indicated in Scheme 4, it is possible that the indenyl
ligand is induced to ring slippage from η5 to η3 coordina-
tion by the incoming alkyne (Chart 1, A), to form an
Ru-alkyne π-bond, as in [RuH(η2-PhCtCH)(η3-C9H7)-
(dppm)]. An alternative pathway may arise from strain
in the four-membered ring of the Ru-dppm bite. The
push from the entering phenylacetylene may in fact
induce ring opening and formation of the transient
species [RuH(η2-PhCtCH)(η5-C9H7)(dppm-kP)], in which
dppm is monodentate (Chart 1, B), more efficiently than
Sch em e 4
k1 (slow)
[RuH(η5-C9H7)(dppm)] + PhCtCH y
z
k-1
{intermediate}
{intermediate} (fast)8
k2
[Ru(CHdCHPh)(η5-C9H7)(dppm)]
first step (k1) is rate-determining and forms a transient
intermediate, under steady-state conditions, which rap-
idly converts into the product (k2). In such a case, the
bimolecular intermediate would not be detectable. This
situation is described by eq 3. The forward transforma-
k1k2[PhCtCH]
kobs
)
(3)
k-1 + k2
tion of the intermediate is much faster than its reversal
to the starting material (k2 . k-1), resulting in a linear
dependence of kobs on [PhCtCH] (eq 2, Figure 2).
The reaction with phenylacetylene is dependent upon
the structure of the hydride complex, with regard to
both the phosphine and the η5 ligands. A role of the
four-membered ring of dppm is indicated by the fact that
exchange of dppm in [RuH(η5-C9H7)(dppm)] for either
dppe or monodentate phosphine ligands inhibits the
process. The small P-Ru-P “bite” angle in the dppm
complex leaves larger space for an incoming molecule
to attack at the metal center, with respect to more
crowded complexes. Relevant as well may be a ring-
opening process through Ru-P bond breaking, as an
effect of ring strain, to produce a temporarily free
coordination site. In fact, the tendency of dppm to act
(17) (a) Puddephatt, R. J . Chem. Soc. Rev. 1983, 12, 99. (b) Anderson,
G. K. Adv. Organomet. Chem. 1993, 35, 1.
(18) (a) Gamasa, M. P.; Gimeno, J .; Lastra, E.; Lanfranchi, M.;
Tiripicchio, A. J . Organomet. Chem. 1992, 430, C39. (b) Gamasa, M.
P.; Gimeno, J .; Lastra, E.; Lanfranchi, M.; Tiripicchio, A. J . Organomet.
Chem. 1991, 405, 333.
(19) (a) Merola, J . S.; Kacmarcik, R. T.; Van Engen, D. J . Am. Chem.
Soc. 1986, 108, 329. (b) Habib, A.; Tanke, R. S.; Holt, E. M.; Crabtree,
R. H. Organometallics 1989, 8, 1225.

Reaction of PhCtCH with [RuH(η5-C9H7)(dppm)]
Organometallics, Vol. 16, No. 25, 1997 5477
in the analogous cyclopentadienyl complex [RuH(η5-
C5H5)(dppm)]. In this respect, it has been observed that
the exchange of triphenylphosphine with alkylarylphos-
phines in [RuCl(η5-ligand)(PPh3)2] (ligand ) C9H7, C5H5)
occurs through a dissociative mechanism not involving
ring-slipped intermediates. The reaction of the indenyl
complex is 1 order of magnitude faster than that of the
cyclopentadienyl analogue, implying a weaker Ru-P
bond in the indenyl species and easier bond rupture in
the transition state of the rate-determining step.20
quirements for the metal complex. Only the indenyl
complex [RuH(η5-C9H7)(dppm)], coordinated by the short-
bite bis(diphenylphosphino)methane ligand, undergoes
insertion of PhCtCH to form the corresponding σ-vinyl
derivative, whereas the cyclopentadienyl analog [RuH-
(η5-C5H5)(dppm)] does not react, thus representing
another case of the indenyl effect. The mechanism is
associative, and formation of a reactive intermediate
between the hydride complex and alkyne occurs slowly
and precedes fast hydride transfer from ruthenium to
the triple bond.
Con clu sion s
Ack n ow led gm en t. Financial support from the DGI-
CYT (Project PB93-325), grants from the FICYT de
Asturias (to B.M.-V. and C.G.-B.), and a travel award
from NATO (Collaborative Research Grant 950794) are
gratefully acknowledged.
Different ruthenium hydride indenyl complexes react
easily with activated alkynes, such as methyl propiolate
and dimethyl acetylenedicarboxylate, leading to regio-
and stereoselective insertion products. The reactions
are strongly dependent on the ancillary ligands, since
only those complexes containing the less sterically
demanding systems are reactive. Moreover, the reac-
tion with phenylacetylene has peculiar structural re-
Su p p or tin g In for m a tion Ava ila ble: Text giving spec-
troscopic and elemental analysis data for the neutral hydride
complexes (2 pages). Ordering information is given on any
current masthead page.
(20) Gamasa, M. P.; Gimeno, J .; Gonza´lez-Bernardo, C.; Mart´ın-
Vaca, B. M.; Monti, D.; Bassetti, M. Organometallics 1996, 15, 302.
OM970489D