Reactivity of indenyl-ruthenium(II) vinylidene complexes: Selective synthesis of alkenyl-phosphonio derivatives via nucleophilic addition of triphenylphosphine on their η2-alkyne tautomers. Theoretical study of the η1-vinylidene-η2-alkyne tautomerization

Article abstract of DOI:10.1021/om010308e

The activation of terminal alkynes with the halide derivatives [RuX(η⁵-1,2,3-R₃C₉H₄) (CO)(PR₃)] (R = Me, X = Br, PR₃ = PPh₃ (1), PⁱPr₃ (3); R = H, X = I, PR₃ = PⁱPr₃ (2)) and AgBF₄ affords, in dichloromethane at room temperature, equilibrium mixtures containing the corresponding η¹-vinylidene and η²-alkyne tautomers [Ru{=C=C(H)R′}(η⁵-1,2,3-R₃ C₉H₄) (CO)(PR₃)][BF₄] (4a-c) and [Ru(η²-HC≡CR′) (η⁵-1,2,3-R₃C₉H₄)(CO) (PR₃)][BF₄] (5a-c), respectively. The reaction of 1 with AgBF₄ and phenylacetylene has been studied by variable-temperature ³¹P{¹H} and ¹H NMR spectroscopy: at low temperature (-60°C) the vinylidene complex [Ru{=C=C(H)Ph}(η⁵-1,2,3-Me₃C₉H₄) (CO)(PPh₃)][BF₄] (4a) is initially observed which upon warming (14°C) forms an equilibrium with the π-alkyne derivative [Ru(η²-HC≡CPh)(η⁵-1,2,3-Me₃ C₉H₄) (CO)(PPh₃)][BF₄] (5a). Treatment of this mixture with KO^tBu, in dichloromethane at room temperature selectively yields the neutral σ-alkynyl derivative [Ru(C≡CPh)(η⁵-1,2,3-Me₃C₉ H₄) (CO)(PPh₃)] (6) by displacement of the aforementioned equilibrium via deprotonation of the acidic vinylidene proton in 4a, while the addition of PPh₃ to this mixture stereoselectively affords the cationic alkenyl-phosphonio complex (E)-[Ru{C(H)=C(PPh₃)Ph} (η⁵-1,2,3-Me₃C₉H₄) (CO) (PPh₃)][BF₄] [(E)-7] via the nucleophilic attack of the PPh₃ on the coordinated π-alkyne in 5a. In a similar fashion, compounds (E)-[Ru{C(H)=C(PPh₃)R′}(η⁵-1,2,3,- R₃C₉H₄) (CO)(PR₃)][BF₄] R = Me, PR₃ = PPh₃, R′ = 1-cyclooctenyl [(E)-13]; R = H, PR₃ = PⁱPr₃, R′ = Ph [(E)-8], 1-cyclooctenyl [(E)-14] can be selectively obtained by addition of PPh₃ to the corresponding reaction mixture. The monosubstituted alkenyl-vinylidene complexes [Ru{=C=C(H)CH=CRR′}(η⁵-C₉H₇) (PPh₃)₂][BF₄] (R = R′ = Ph (11a); R = H, R′ = (η⁵-C₅H₄) Fe(η⁵-C₅H₅) [(E)-11b], 4-OMe-C₆H₄ [(Z)-11c]) also react with triphenylphosphine, but in refluxing methanol, to afford the alkenyl-phosphonio derivatives (EE)-[Ru{C(H)=C(PPh₃)CH=CRR′}(η⁵-C₉ H₇)(PPh₃)₂][BF₄] (12a-c) stereoselectively. The process also proceeds via an initial η¹-vinylidene-η²-alkyne tautomerization followed by the nucleophilic attack of PPh₃ on the coordinated π-alkyne. The crystal structures of (E)-[Ru{C(H)=C(PPh₃)Ph}(η⁵-1,2,3-Me₃ C₉H₄)(CO)(PPh₃)][BF₄] ((E)-7) and (EE)-[Ru{C(H)=C(PPh₃)CH=CH(η⁵-C₅ H₄)Fe(η⁵-C₅H₅)} (η⁵-C₉H₇)(PPh₃)₂] [BF₄] ((EE)-12b) have been determined by X-ray diffraction methods. Ab initio molecular orbital calculations on the η¹-vinylidene to η²-alkyne tautomerization on the models [Ru(η⁵-C₉H₇)(PH₃)L(C₂ H₂)]⁺ (L = CO, PH₃) also reported.

Full text of DOI:10.1021/om010308e

Organometallics 2001, 20, 5177-5188
5177
Rea ctivity of In d en yl-Ru th en iu m (II) Vin ylid en e
Com p lexes: Selective Syn th esis of Alk en yl-P h osp h on io
Der iva tives via Nu cleop h ilic Ad d ition of
Tr ip h en ylp h osp h in e on Th eir η2-Alk yn e Ta u tom er s.
Th eor etica l Stu d y of th e η1-Vin ylid en e-η2-Alk yn e
Ta u tom er iza tion
Victorio Cadierno, M. Pilar Gamasa, J ose´ Gimeno,* and
Covadonga Gonza´lez-Bernardo
Departamento de Quı´mica Orga´nica e Inorga´nica, Instituto Universitario de Quı´mica
Organometa´lica “Enrique Moles” (Unidad Asociada al CSIC), Facultad de Qu´ımica,
Universidad de Oviedo, E-33071 Oviedo, Spain
Enrique Pe´rez-Carren˜o and Santiago Garc´ıa-Granda
Departamento de Quı´mica Fı´sica y Analı´tica, Facultad de Qu´ımica, Universidad de Oviedo,
E-33071 Oviedo, Spain
Received April 13, 2001
The activation of terminal alkynes with the halide derivatives [RuX(η5-1,2,3-R3C9H4)(CO)-
(PR3)] (R ) Me, X ) Br, PR3 ) PPh3 (1), PiPr3 (3); R ) H, X ) I, PR3 ) PiPr3 (2)) and AgBF4
affords, in dichloromethane at room temperature, equilibrium mixtures containing the
corresponding η1-vinylidene and η2-alkyne tautomers [Ru{)CdC(H)R′}(η5-1,2,3-R3C9H4)-
(CO)(PR3)][BF4] (4a -c) and [Ru(η2-HCtCR′)(η5-1,2,3-R3C9H4)(CO)(PR3)][BF4] (5a -c), re-
spectively. The reaction of 1 with AgBF4 and phenylacetylene has been studied by variable-
1
temperature 31P{1H} and H NMR spectroscopy: at low temperature (-60 °C) the vinylidene
complex [Ru{dCdC(H)Ph}(η5-1,2,3-Me3C9H4)(CO)(PPh3)][BF4] (4a ) is initially observed which
upon warming (14 °C) forms an equilibrium with the π-alkyne derivative [Ru(η2-HCtCPh)-
(η5-1,2,3-Me3C9H4)(CO)(PPh3)][BF4] (5a ). Treatment of this mixture with KOtBu, in dichlo-
romethane at room temperature selectively yields the neutral σ-alkynyl derivative [Ru(Ct
CPh)(η5-1,2,3-Me3C9H4)(CO)(PPh3)] (6) by displacement of the aforementioned equilibrium
via deprotonation of the acidic vinylidene proton in 4a , while the addition of PPh3 to this
mixture stereoselectively affords the cationic alkenyl-phosphonio complex (E)-[Ru{C(H)d
C(PPh3)Ph}(η5-1,2,3-Me3C9H4)(CO)(PPh3)][BF4] [(E)-7] via the nucleophilic attack of PPh3
on the coordinated π-alkyne in 5a . In a similar fashion, compounds (E)-[Ru{C(H)dC(PPh3)-
R′}(η5-1,2,3-R3C9H4)(CO)(PR3)][BF4] (R ) Me, PR3 ) PPh3, R′ ) 1-cyclooctenyl [(E)-13]; R )
H, PR3 ) PiPr3, R′ ) Ph [(E)-8], 1-cyclooctenyl [(E)-14] can be selectively obtained by addition
of PPh3 to the corresponding reaction mixture. The monosubstituted alkenyl-vinylidene
complexes [Ru{dCdC(H)CHdCRR′}(η5-C9H7)(PPh3)2][BF4] (R ) R′ ) Ph (11a ); R ) H, R′ )
(η5-C5H4)Fe(η5-C5H5) [(E)-11b], 4-OMe-C6H4 [(Z)-11c]) also react with triphenylphosphine,
but in refluxing methanol, to afford the alkenyl-phosphonio derivatives (EE)-[Ru{C(H)d
C(PPh3)CHdCRR′}(η5-C9H7)(PPh3)2][BF4] (12a -c) stereoselectively. The process also proceeds
via an initial η1-vinylidene-η2-alkyne tautomerization followed by the nucleophilic attack
of PPh3 on the coordinated π-alkyne. The crystal structures of (E)-[Ru{C(H)dC(PPh3)Ph}-
(η5-1,2,3-Me3C9H4)(CO)(PPh3)][BF4] ((E)-7) and (EE)-[Ru{C(H)dC(PPh3)CHdCH(η5-C5H4)-
Fe(η5-C5H5)}(η5-C9H7)(PPh3)2][BF4] ((EE)-12b) have been determined by X-ray diffraction
methods. Ab initio molecular orbital calculations on the η1-vinylidene to η2-alkyne tautomer-
ization on the models [Ru(η5-C9H7)(PH3)L(C2H2)]+ (L ) CO, PH3) are also reported.
In tr od u ction
well-established that the stability and properties of such
derivatives are essentially a function of the nature of
both the metal center and its ancillary ligands.1 In
particular, electron-rich ruthenium(II) complexes have
proven to be appropiate precursors for the preparation
of stable vinylidene derivatives.1 This fact has allowed
the study in detail of their chemical behavior, and, by
the aid of these studies, very useful synthetic applica-
tions have recently emerged.2
A great deal of attention has been devoted to the
chemistry of transition-metal vinylidene complexes
[M]dCdCR2 during the past 2 decades.1 Thus, it is now
* To whom correspondence should be addressed. E-mail: jgh@sauron.
quimica.uniovi.es.
(1) For comprehensive reviews see: (a) Antonova, A. B.; Ioganson,
A. A. Russ. Chem. Rev. (Engl. Transl.) 1989, 58, 693. (b) Bruce, M. I.
Chem. Rev. 1991, 91, 197. (c) Werner, H. Nachr. Chem. Technol. Lab.
1992, 40, 435. (d) Werner, H. J . Organomet. Chem. 1994, 475, 45. (e)
Bruneau, C.; Dixneuf, P. H. Acc. Chem. Res. 1999, 32, 311. (f) Puerta,
M. C.; Valerga, P. Coord. Chem. Rev. 1999, 193-195, 977.
One of the most important reasons for the growing
development of the chemistry of ruthenium(II)-vi-
10.1021/om010308e CCC: $20.00 © 2001 American Chemical Society
Publication on Web 11/02/2001

5178 Organometallics, Vol. 20, No. 24, 2001
Cadierno et al.
nylidenes is that they are readily accessible from simple
terminal alkynes.1 The mechanism of this 1-alkyne to
vinylidene rearrangement has been extensively studied
both experimentally and theoretically, and it is now
well-known that it depends on the nature of the
ruthenium fragment. Nevertheless, as a common fact,
the mechanism involves the initial side-on coordination
of the alkyne to ruthenium, to form an intermediate η2-
alkyne complex.3 Significantly, η2-alkyne complexes [Ru-
(η2-HCtCR)(η5-C5H5)L2]+ (R ) H, L ) PMe2Ph, L2 )
1,2-bis(diisopropylphosphino)ethane; R ) Me, L ) PMe3)
have been isolated as stable intermediates in the
formation of the corresponding vinylidene derivatives
[Ru{dCdC(H)R}(η5-C5H5)L2]+.3b,4 Although it has not
been extensively studied, the reverse process, i.e.,
interconversion of ruthenium(II)-vinylidenes into their
corresponding η2-alkyne tautomers, has been also shown
to occur in a few cases.5
than the η2-alkyne complex and (ii) the calculated
energy barrier to reach the π-alkyne species from the
vinylidene is low enough to be overcome under normal
experimental reaction conditions (ca. 60 °C). In ac-
cordance with these expectations, we have found that
the vinylidene moiety in monosubstituted complexes
[Ru{dCdC(H)R}(η5-C9H7)(PPh3)2]+ is labile, being eas-
ily replaced by nitriles, at refluxing temperatures, to
form [Ru(NtCR′)(η5-C9H7)(PPh3)2]+ and the correspond-
ing terminal alkyne which are generated by the dis-
placement of the π-coordinated alkyne in the transient
[Ru(η2-HCtCR)(η5-C9H7)(PPh3)2]+ species.6,7
Continuing with these studies herein we describe (i)
the activation of terminal alkynes by the electrophilic
carbonyl compounds [RuX(η5-1,2,3-R3C9H4)(CO)(PR3)]
(R ) Me, X ) Br, PR3 ) PPh3, PiPr3; R ) H, X ) I, PR3
) PiPr3) which leads to equilibrium mixtures containing
both η1-vinylidene and η2-alkyne species; (ii) the syn-
thesis of alkenyl-phosphonio derivatives (E)-[Ru{C(H)d
C(PPh3)R′}(η5-1,2,3-R3C9H4)(CO)(PR3)]+ obtained by ad-
dition of PPh3 to the aforementioned equilibrium
mixtures which are displaced easily at room tempera-
ture toward the formation of the π-alkyne complexes
(this allows the selective nucleophilic attack of the
phosphine to afford the alkenyl-phosphonio complexes);
and (iii) the synthesis of analogous alkenyl-phosphonio
complexes (E)-[Ru{C(H)dC(PPh3)R}(η5-C9H7)(PPh3)2]+,
via the regioselective nucleophilic addition of PPh3 on
the π-alkyne complexes [Ru(η2-CtCR)(η5-C9H7)(PPh3)2]+
generated as transient species from the corresponding
stable vinylidene derivatives [Ru{dCdC(H)R}(η5-C9H7)-
(PPh3)2]+ in refluxing methanol. To study the electronic
properties of the electrophilic indenyl-ruthenium(II)
fragments [Ru(η5-1,2,3-R3C9H4)(CO)(PR3)], which enable
the easy tautomerization of the vinylidene moiety into
the π-alkyne ligand, ab initio molecular orbital calcula-
We have recently reported ab initio molecular orbital
(MO) calculations on the η1-vinylidene-η2-alkyne tau-
tomerization reaction path, back and forth of the equi-
librium between [Ru(dCdCH2)(η5-C9H7)(PH3)2]+ and
[Ru(η2-HCtCH)(η5-C9H7)(PH3)2]+.6 It is shown that (i)
the vinylidene species is thermodinamically more stable
(2) Ruthenium(II) vinylidene complexes have been shown to be
excellent promoters for selective C-C coupling reactions. For recent
references see: (a) Slugovc, C.; Mereiter, K.; Schmid, R.; Kirchner, K.
J . Am. Chem. Soc. 1998, 120, 6175. (b) J ia, G.; Lau, C. P. J . Organomet.
Chem. 1998, 565, 37, and references therein. (c) Yi, C. S.; Liu, N.
Organometallics 1998, 17, 3158. (d) Huang, D.; Oliva´n, M.; Huffman,
J . C.; Eisenstein, O.; Caulton, K. G. Organometallics 1998, 17, 4700.
(e) Yam, V. W. W.; Chu, B. W. K.; Cheung, K. K. Chem. Commun.
1998, 2261. (f) Slugovc, C.; Mereiter, K.; Schmid, R.; Kirchner, K. Eur.
J . Inorg. Chem. 1999, 1141. (g) J ime´nez Tenorio, M. A.; J ime´nez
Tenorio, M.; Puerta, M. C.; Valerga, P. Organometallics 2000, 19, 1333.
(h) Bruce, M. I.; Hall, B. C.; Skelton, B. W.; White, A. H.; Zaitseva, N.
N. J . Chem. Soc., Dalton Trans. 2000, 2279. (i) Lin, Y. C. J . Organomet.
Chem. 2001, 617-618, 141, and references therein. (j) Pavlik, S.;
Gemel, C.; Slugovc, C.; Mereiter, K.; Schmid, R.; Kirchner, K. J .
Organomet. Chem. 2001, 617-618, 301, and references therein. They
are also active catalysts for the ring-opening metathesis polymerization
(ROMP) of olefines: (k) Schwab, P.; Grubbs, R. H.; Ziller, J . W. J . Am.
Chem. Soc. 1996, 118, 100. (l) Katayama, H.; Ozawa, F. Chem. Lett.
1998, 67. (m) Katayama, H.; Yoshida, T.; Ozawa, F. J . Organomet.
Chem. 1998, 562, 203. (n) del Rio, I.; van Koten, G. Tetrahedron Lett.
1999, 40, 1401. (o) Katayama, H.; Urushima, H.; Ozawa, F. J .
Organomet. Chem. 2000, 606, 16. (p) Saoud, M.; Romerosa, A.;
Peruzzini, M. Organometallics 2000, 19, 4005.
(3) Following this initial step two different pathways have been
proposed: (i) an intramolecular [1,2]-H shift to give the thermody-
namically favored vinylidene isomer (for ab initio molecular orbital
(MO) calculations on the rearrangement of [Ru(η2-HCtCH)Cl2(PH3)2]
to [Ru(dCdCH2)Cl2(PH3)2] supporting this intramolecular process
see: (a) Wakatsuki, Y.; Koga, N.; Yamazaki, H.; Morokuma, K. J . Am.
Chem. Soc. 1994, 116, 8105), and (ii) the formation of an intermediate
hydride-alkynyl [Ru(H)(CtCR)] complex, through the oxidative ad-
dition of the coordinated alkyne, followed by a hydrogen shift to the
Câ atom of the alkynyl group to afford the final vinylidene tautomer
[Ru{dCdC(H)R}]: (b) de los Rios, I.; J ime´nez-Tenorio, M.; Puerta, M.
C.; Valerga, P. J . Am. Chem. Soc. 1997, 119, 6529. (c) Bustelo, E.;
J ime´nez-Tenorio, M.; Puerta, M. C.; Valerga, P. Organometallics 1999,
18, 4563. It should be noted that η2-alkyne to η1-vinylidene tautomer-
izations promoted by d8 (Co(I), Rh(I), Ir(I)) metal complexes have been
theoretically [(d) Wakatsuki, Y.; Koga, N.; Werner, H.; Morokuma, K.
J . Am. Chem. Soc. 1997, 119, 360. (e) Pe´rez-Carren˜o, E.; Paoli, P.;
Ienco, A.; Mealli, C. Eur. J . Inorg. Chem. 1999, 1315.] and experimen-
tally proved to occur also through this oxidative mechanism. See for
example, the following. Co(I): (f) Bianchini, C.; Peruzzini, M.; Vacca,
A.; Zanobini, F. Organometallics 1991, 10, 3697. Rh(I): (g) Windmu¨ller,
B.; Wolf, J .; Werner, H. J . Organomet. Chem. 1995, 502, 147. (h)
Werner, H.; Gevert, O.; Steinert, P.; Wolf, J . Organometallics 1995,
14, 1786. (i) Wiedemann, R.; Fleischer, R.; Stalke, D.; Werner, H.
Organometallics 1997, 16, 866. (j) Kovacik, I.; Laubender, M.; Werner,
H. Organometallics 1997, 16, 5607, and references therein. Ir(I): (k)
Lass, R. W.; Steinert, P.; Wolf, J .; Werner, H. Chem. Eur. J . 1996, 2,
19. (l) Werner, H.; Lass, R. W.; Gevert, O.; Wolf, J . Organometallics
1997, 16, 4077, and references therein.
(5) The complex [Ru(dCdCH2)Cl(κ2-P,O-iPr2PCH2CH2OMe)2]+ is
stable only under an acetylene atmosphere indicating a reversible
process: (a) Mart´ın, M.; Gevert, O.; Werner, H. J . Chem. Soc., Dalton
Trans. 1996, 2275. The reaction of [Ru{dCdC(H)Ph}Cl(κ2-P,O-iPr2-
PCH2CH2OMe)2]+, [Ru{dCdC(H)Ph}{dC(NHPh)(CH2Ph)}Cl(PNP)]+
(PNP ) nPrN(CH2CH2PPh2)2) and [Ru{dCdC(H)R}(η5-C5H5)(tmeda)]+
(R ) tBu, SiMe3; tmeda ) Me2N(CH2)2NMe2) with CO which yields
the free terminal alkyne and the carbonyl compounds [RuCl(CO)(κ2-
P,O-iPr2PCH2CH2OMe)2]+, [Ru{dC(NHPh)(CH2Ph)}Cl(CO)(PNP)]+ and
[Ru(η5-C5H5)(CO)(tmeda)]+, respectively, seems to proceed via an
intermediate η2-alkyne complex. See ref 5a and: (b) Bianchini, C.;
Purches, G.; Zanobini, F.; Peruzzini, M. Inorg. Chim. Acta 1998, 272,
1. (c) Gemel, C.; Huffman, J . C.; Caulton, K. G.; Mauthner, K.;
Kirchner, K. J . Organomet. Chem. 2000, 593-594, 342. Similarly,
when complex [RuI2{dCdC(H)Ph}(κ2-P,O-iPr2PCH2CH2OMe)(κ-P-iPr2-
PCH2CH2OMe)] is heated at a high temperature, phenylacetylene is
recovered with concomitant formation of trans-[RuI2(κ2-P,O-iPr2PCH2-
CH2OMe)2] (see ref 5a). The vinylidene moiety is also displaced from
the reaction of [Ru{dCdC(H)Me}(η5-C5H5)(PMe3)2]+, trans-[Ru(CtCR)-
{dCdC(H)R}{P(OR)3}4]+ and [Ru{dCdC(H)R}Cl{HB(pz)3}(PPh3)] with
two electron ligands (L ) phosphines, phosphites, nitriles, isocyanides
or CO) to give the free terminal alkyne and [Ru(η5-C5H5)(L)(PMe3)2]+,
trans-[Ru(CtCR)(L){P(OR)3}4]+ or [RuCl{HB(pz)3}(L)(PPh3)], respec-
tively. See ref 4a and: (d) Albertin, G.; Antoniutti, S.; Bordignon, E.;
Cazzaro, F.; Ianelli, S.; Pellizi, G. Organometallics 1995, 14, 4114. (e)
Slugovc, C.; Sapunov, V. N.; Wiede, P.; Mereiter, K.; Schmid, R.;
Kirchner, K. J . Chem. Soc., Dalton Trans. 1997, 4209. Finally, the
formation of [RuCl(η5-C5Me5){P(OR)3}2] by treatment of vinylidene
complexes [RuCl{dCdC(H)R}(η5-C5Me5)(PPh3)] with phosphites has
been also reported: (f) Bruce, M. I.; Hall, B. C.; Zaitseva, N. N.; Skelton,
B. W.; White, A. H. J . Organomet. Chem. 1996, 522, 307.
(6) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Pe´rez-Carren˜o, E.;
Garc´ıa-Granda, S. Organometallics 1999, 18, 2821.
(7) (a) Cadierno, V.; Conejero, S.; Gamasa, M. P.; Gimeno, J . J .
Chem. Soc., Dalton Trans. 2000, 451. (b) Cadierno, V.; Gamasa, M.
P.; Gimeno, J . J . Organomet. Chem. 2001, 621, 39. (c) Cadierno, V.;
Conejero, S.; Gamasa, M. P.; Gimeno, J .; Pe´rez-Carren˜o, E.; Garc´ıa-
Granda, S. Organometallics 2001, 20, 3175.
(4) (a) Bullock, R. M. J . Chem. Soc., Chem. Commun. 1989, 165. (b)
Lomprey, J . R.; Selegue, J . P. J . Am. Chem. Soc. 1992, 114, 5518.

Indenyl-Ruthenium(II) Vinylidene Reactivity
Organometallics, Vol. 20, No. 24, 2001 5179
Sch em e 1
tions are also reported. This has allowed us a rational
comparation of its chemical behavior with respect to
that of the analogous fragment [Ru(η5-C9H7)(PPh3)2].
Part of this work has been preliminarily communicated.8
new singlet resonance at δ 3.71 ppm assigned to the
tCH proton of the π-coordinated phenylacetylene mol-
ecule.10 When the solution is gradually warmed to 14
°C, the signals due to 4a slowly decrease, while those
assigned to 5a increase to obtain a final ratio 4a :5a of
1:1.5. The formation of minor uncharacterized species
was also observed starting from -25 °C. This is con-
firmed by the 31P{1H} NMR spectrum which shows at
room temperature the presence in solution of six dif-
ferent compounds, being 4a and 5a the major reaction
products.11
The treatment of this reaction mixture with KOtBu
at room temperature strongly support the existence of
an η1-vinylidene-η2-alkyne equilibrium since the neu-
tral σ-alkynyl derivative [Ru(CtCPh)(η5-1,2,3-Me3C9H4)-
(CO)(PPh3)] (6) is generated in high yield (75%), via
deprotonation of the acidic vinylidene proton of 4a
(Scheme 1).8 Complex 6 has been characterized by IR
and NMR (1H, 31P{1H}, and 13C{1H}) spectroscopy and
mass spectrometry (FAB) showing spectroscopic proper-
ties similar to those reported for other indenyl-ruthe-
nium(II) σ-alkynyl derivatives (details are given in the
Experimental Section).7,12 In particular, the presence of
the alkynyl group is confirmed by the appearance of (i)
a ν(CtC) absorption band at 2093 cm-1 in the IR
spectrum (KBr), and (ii) a typical doublet resonance
(2J CP ) 25.0 Hz) for the Ru-CR in the 13C{1H} NMR
spectra at δ 109.87 ppm, the Câ carbon resonance falling
within the aromatic region.
Resu lts
Activa tion of P h en yla cetylen e by [Ru X(η5-1,2,3-
R3C9H4)(CO)(P R3)] (R ) Me, X ) Br , P R3 ) P P h 3,
P iP r 3; R ) H, X ) I, P R3 ) P iP r 3). The treatment of
complexes [RuX(η5-1,2,3-R3C9H4)(CO)(PR3)] (R ) Me, X
) Br, PR3 ) PPh3 (1), PiPr3 (3); R ) H, X ) I, PR3 )
PiPr3 (2))9 with an slight excess of AgBF4 (ca. 1.1:1) in
dichloromethane at room temperature leads, as moni-
tored by IR spectroscopy, to the clean formation of the
highly unstable tetrafluoroborate adducts [Ru(FBF3)-
(η5-1,2,3-R3C9H4)(CO)(PR3)]. These species cannot be
isolated and, when treated in situ with phenylacetylene,
afford complicated reaction mixtures containing the
corresponding vinylidene complexes [Ru{dCdC(H)Ph}-
(η5-1,2,3-R3C9H4)(CO)(PR3)][BF4] (4a -c) in equilibrium
with its η2-alkyne tautomers [Ru(η2-HCtCPh)(η5-1,2,3-
R3C9H4)(CO)(PR3)][BF4] (5a -c), as the major reaction
products, as well as additional uncharacterized orga-
nometallic species (Scheme 1). To get information of the
course of these processes, the reaction of 1 with AgBF4
and phenylacetylene has been monitored by 31P{1H} and
1H NMR spectroscopy at variable temperatures (details
are given in the Experimental Section). Thus, at low
temperature (-60 °C), the formation of the vinylidene
complex 4a is initially observed as inferred clearly from
the apparition of a typical RudCdCH proton resonance
at δ 4.76 ppm in the 1H NMR spectrum. At this
temperature, 4a slowly forms an equilibrium with 5a
(ca. ratio 4a :5a ) 1:1.1). The formation of 5a is sup-
These results are in accordance with those recently
reported by Lugan and co-workers who described that
the protonation of [Ru(CtCPh)(η5-C5H5)(CO)(PPh3)] at
low temperature (-80 °C) selectively affords the vi-
(10) The resonances assigned to the vinylidene [Ru]dCdCHPh and
π-alkyne [Ru](η2-HCtCPh) protons are in accordance with data
reported in the literature. See refs 3b,c, 4 and: Nombel, P.; Lugan,
N.; Mathieu, R. J . Organomet. Chem. 1995, 503, C22.
1
ported by the presence in the H NMR spectrum of a
(8) Gamasa, M. P.; Gimeno, J .; Gonza´lez-Bernardo, C.; Borge, J .;
Garc´ıa-Granda, S. Organometallics 1997, 16, 2483.
(9) (a) Cadierno, V.; D´ıez, J .; Gamasa, M. P.; Gimeno, J .; Lastra, E.
Coord. Chem. Rev. 1999, 193-195, 147. (b) Gamasa, M. P.; Gimeno,
J .; Gonza´lez-Bernardo, C. Manuscript in preparation.
(11) We note that hydride-alkynyl ruthenium(IV) species were not
detected by 1H NMR spectroscopy. In agreement with this we have
found that the calculated energy value for [Ru(H)(CtCH)(η5-C9H7)-
(CO)(PH3)] is 40.2 kcal/mol, similar to that found for the transition
state D (L ) PH3) (Figure 5).

5180 Organometallics, Vol. 20, No. 24, 2001
Cadierno et al.
Sch em e 2
nylidene derivative [Ru{dCdC(H)Ph}(η5-C5H5)(CO)-
(PPh3)]+ which, upon warming to room temperature,
readily isomerizes to give a mixture with its η2-alkyne
tautomer [Ru(η2-HCtCPh)(η5-C5H5)(CO)(PPh3)]+.10
Syn th esis of Alk en yl-P h osp h on io Com p lexes
(E)-[R u {C(H )dC(P P h 3)P h }(η5-1,2,3-R 3C9H 4)(CO)-
displays the typical low-field resonance for the Ru-CR
atom in alkenyl complexes, as a doublet of doublets at
δ 206.52 ppm (2J CP ) 13.9 and 2.8 Hz), as well as the
doublet signal (J CP ) 85.1 Hz) due to the Câ nucleus at
δ 121.28 ppm. Furthermore, the E stereochemistry
proposed for 7 was undoubtedly confirmed by means of
X-ray diffraction methods (see below).
(P R3)][BF 4] (R ) Me, P R3 ) P P h 3; R ) H, P R3
)
P iP r 3). The formation of the transient π-alkyne species
5a is also assessed by the addition at room temperature
of 1 equiv of triphenylphosphine to a dichloromethane
solution containing complexes 4a and 5a . The equilib-
rium between these species is readily displaced, via the
regioselective nucleophilic attack of PPh3 on the η2-
coordinated phenylacetylene molecule on 5a , to form the
cationic alkenyl-phosphonio derivative (E)-[Ru{C(H)d
C(PPh3)Ph}(η5-1,2,3-Me3C9H4)(CO)(PPh3)][BF4] [(E)-7;
60% yield; Scheme 1].13 The NMR data are in agreement
with the presence of an alkenyl-phosphonio chain
(details are given in the Experimental Section) and can
be compared to those reported for other indenyl-
ruthenium(II) alkenyl complexes.12e,14 Thus, the 31P{1H}
NMR spectrum displays resonances consistent with an
AM spin system (δ 16.70 (d, C-PPh3) and 52.82 (d, Ru-
Under similar reaction conditions complex (E)-[Ru-
{C(H)dC(PPh3)Ph}(η5-C9H7)(CO)(PiPr3)][BF4] [(E)-8] has
also been prepared (70% yield; Scheme 1). In contrast,
the addition of PPh3 to the reaction mixture resulting
from the treatment of 3 with AgBF4 and phenylacety-
lene proceeds through a different way. Thus, IR and
NMR (31P{1H} and 1H) spectroscopies indicate the
formation of a mixture containing the expected alkenyl-
phosphonio derivative (E)-[Ru{C(H)dC(PPh3)Ph}(η5-
1,2,3-Me3C9H4)(CO)(PiPr3)][BF4] [(E)-9] and the bispho-
sphine complex [Ru(η5-1,2,3-Me3C9H4)(CO)(PPh3)(PiPr3)]-
[BF4] (10) (ca. ratio 1:1.6) (Scheme 2). Assuming that
an equilibrium of the type shown in Scheme 1 is
operative, the formation of 10 is probably the result of
the competitive η2-phenylacetylene substitution by PPh3
vs the nucleophilic addition of the phosphine on the η2-
coordinated alkyne. It is apparent that the metallic
fragment [Ru(η5-1,2,3-Me3C9H4)(CO)(PiPr3)] is sterically
more demanding toward the coordination of the alkyne
than the analogous [Ru(η5-C9H7)(CO)(PiPr3)] and [Ru-
(η5-1,2,3-Me3C9H4)(CO)(PPh3)] moieties, increasing there-
fore its lability, which allows the partial substitution
by PPh3.
Syn th esis of Alk en yl-P h osp h on io Com p lexes
(EE)-[Ru {C(H)dC(P P h 3)CHdCRR′}(η5-C9H7)(P P h 3)2]-
[BF 4] (R ) R′ ) P h ; R ) H, R′ ) (η5-C5H4)F e(η5-
C5H5), 4-OMe-C6H4). Since the alkenyl-phosphonio
complexes (E)-7,8 are generated from the selective
nucleophilic attack to the π-alkyne complexes 5a -b, we
believed it would be interesting to explore the scope of
this reaction starting from stable vinylidene complexes
[Ru{dCdC(H)R}(η5-C9H7)(PPh3)2]+ for which we proved
previously that a tautomerization to the corresponding
π-alkyne can be achieved.6,7 Thus, the monosubstituted
alkenyl-vinylidene derivatives [Ru{dCdC(H)CHd
CRR′}(η5-C9H7)(PPh3)2][BF4] (R ) R′ ) Ph (11a );6 R )
H, R′ ) (η5-C5H4)Fe(η5-C5H5) [(E)-11b],12j 4-OMe-C6H4
[(Z)-11c]6) react with a large excess of PPh3 (ca. 15:1)
in refluxing methanol to give selectively the alkenyl-
phosphonio complexes (EE)-[Ru{C(H)dC(PPh3)CHd
CRR′}(η5-C9H7)(PPh3)2][BF4] (R ) R′ ) Ph (12a ); R )
H, R′ ) (η5-C5H4)Fe(η5-C5H5) [(EE)-12b], 4-OMe-C6H4
[(EE)-12c]), which have been isolated in 66-73% yield
(Scheme 3).
4
PPh3) ppm with J PP ) 6.2 Hz), while the vinylic
hydrogen appears, in the 1H NMR spectrum, as a
downfield doublet of doublets resonance (3J HP ) 32.5
and 7.5 Hz) at δ 9.43 ppm. The 13C{1H} NMR spectrum
(12) (a) Gamasa, M. P.; Gimeno, J .; Mart´ın-Vaca, B. M.; Borge, J .;
Garc´ıa-Granda, S.; Pe´rez-Carren˜o, E. Organometallics 1994, 13, 4045.
(b) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Borge, J .; Garc´ıa-Granda,
S. J . Chem. Soc., Chem. Commun. 1994, 2495. (c) Gamasa, M. P.;
Gimeno, J .; Godefroy, I.; Lastra, E.; Mart´ın-Vaca, B. M.; Garc´ıa-
Granda, S.; Gutierrez-Rodriguez, A. J . Chem. Soc., Dalton Trans. 1995,
1901. (d) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Gonza´lez-Cueva,
M.; Lastra, E.; Borge, J .; Garc´ıa-Granda, S. Organometallics 1996, 15,
2137. (e) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Borge, J .; Garc´ıa-
Granda, S. Organometallics 1997, 16, 3178. (f) Cadierno, V.; Gamasa,
M. P.; Gimeno, J .; Lo´pez-Gonza´lez, M. C.; Borge, J .; Garc´ıa-Granda,
S. Organometallics 1997, 16, 4453. (g) Crochet, P.; Demerseman, B.;
Vallejo, M. I.; Gamasa, M. P.; Gimeno, J .; Borge, J .; Garc´ıa-Granda,
S. Organometallics 1997, 16, 5406. (h) Cadierno, V.; Gamasa, M. P.;
Gimeno, J .; Moreto´, J . M.; Ricart, S.; Roig, A.; Molins, E. Organome-
tallics 1998, 17, 697. (i) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Pe´rez-
Carren˜o, E.; Ienco, A. Organometallics 1998, 17, 5216. (j) Cadierno,
V.; Conejero, S.; Gamasa, M. P.; Gimeno, J .; Asselberghs, I.; Houbre-
chts, S.; Clays, K.; Persoons, A.; Borge, J .; Garc´ıa-Granda, S. Orga-
nometallics 1999, 18, 582. (k) Cadierno, V.; Gamasa, M. P.; Gimeno,
J . J . Chem. Soc., Dalton Trans. 1999, 1857. (l) Cadierno, V.; Gamasa,
M. P.; Gimeno, J .; Lastra, E. J . Chem. Soc., Dalton Trans. 1999, 3235.
(m) Sato, M.; Iawa, A.; Watanabe, M. Organometallics 1999, 18, 3208.
(13) Literature precedents for selective phosphine attack on coor-
dinated alkynes to generate (E)-alkenyl-phosphonio complexes in-
clude: (a) Kolobova, N. E.; Ivanov, L. L.; Zhvanko, O. S.; Chechulina,
I. N.; Batsanov, A. S.; Struchkov, Y. T. J . Organomet. Chem. 1982,
238, 223. (b) Hoffman, D. M.; Huffman, J . C.; Lappas, D.; Wierda, D.
A. Organometallics 1993, 12, 4312. (c) Williams, D. S.; Schofield, M.
H.; Schrock, R. R. Organometallics 1993, 12, 4560. (d) J ung, J . H.;
Hoffman, D. M.; Lee, T. R. J . Organomet. Chem. 2000, 599, 112. (e)
Hansen, H. D.; Nelson, J . H. Organometallics 2000, 19, 4740.
Compounds (EE)-12a -c have been characterized by
elemental analyses, conductance measurements, and IR
and NMR (1H, 31P{1H}, and 13C{1H}) spectroscopies,
being all data in accordance with the proposed formula-
(14) (a) Bassetti, M.; Casellato, P.; Gamasa, M. P.; Gimeno, J .;
Gonza´lez-Bernardo, C.; Mart´ın-Vaca, B. Organometallics 1997, 16,
5470. (b) Gamasa, M. P.; Gimeno, J .; Mart´ın-Vaca, B. M. Organome-
tallics 1998, 17, 3707. (c) Cadierno, V.; Gamasa, M. P.; Gimeno, J .;
Mart´ın-Vaca, B. M. J . Organomet. Chem. 2001, 617-618, 261.

Indenyl-Ruthenium(II) Vinylidene Reactivity
Organometallics, Vol. 20, No. 24, 2001 5181
Sch em e 3
Sch em e 4
tions (details are given in the Experimental Section).
In particular, the H NMR spectra show the expected
1
doublet of triplets resonance (3J HP ) 29.8-33.6 Hz, 3J HP
) 9.7-10.0 Hz) for the vinylic RuCHd proton at ca. δ
10 ppm, while the CR and Câ atoms of the alkenyl chain
appear, in the 13C{1H} NMR spectra, as a multiplet (δ
205.76-214.78 ppm) or a doublet signal (δ 121.06-
122.09 ppm; J CP ) 85.0-88.7 Hz), respectively. It is
interesting to note that complexes 12b,c were obtained
as the thermodynamically stable EE stereoisomers as
inferred clearly from the values of the coupling constant
for the olefinic CHdCH protons (J HH ) 17.1 Hz (12b),
16.7 Hz (12c)). In addition, the structure of (EE)-12b
has been confirmed by X-ray diffraction methods (see
below). Given the stereochemistry of the starting alk-
enyl-vinylidene complexes (E)-11b and (Z)-11c, an
isomerization of the CHdCH double bond on 11c has
taken place. A similar isomerization has been previously
observed in the reaction of 11c with acetonitrile, which
stereoselectively yields (E)-HCtCCHdCH(4-OMe-C6H4)
and [Ru(NtCMe)(η5-C9H7)(PPh3)2][BF4].6
PPh3; R ) H, PR3 ) PiPr3) (obtained in situ from
complexes 1,2 in the presence of AgBF4 in dichlo-
romethane) with 1-ethynyl-1-cyclooctanol. In contrast
to the analogous complexes [RuCl(η5-C9H7)L2], which
are precursors of alkenyl-vinylidene derivatives C, the
reactions of complexes 1,2 lead to complicated mixtures
of products (observed by IR and 31P{1H} NMR spectros-
copy) which could not be identified. To get information
on the composition of these mixtures, 1 equiv of PPh3
was added to the reaction media resulting in the
formation of alkenyl-phosphonio derivatives (E)-[Ru-
{C(H)dC(PPh3)R′}(η5-1,2,3-R3C9H4)(CO)(PR3)][BF4] (R′
) 1-cyclooctenyl; R ) Me, PR3 ) PPh3 [(E)-13]; R ) H,
PR3 ) PiPr3 [(E)-14]) as the main reaction products (60
and 50% isolated yields, respectively) (Scheme 5).
Syn th esis of Alk en yl-P h osp h on io Com p lexes
(E )-[R u {C(H )dC(P P h 3)R ′}(η5-1,2,3-R 3C9H 4)(CO)-
(P R3)][BF 4] (R′ ) 1-Cycloocten yl; R ) Me, P R3
)
P P h 3; R ) H, P R3 ) P iP r 3). We have recently reported
that 1-ethynyl-1-cycloalkanols HCtCC(OH)CH2CH2-
Analytical and spectroscopic data (IR and H, 31P{1H},
1
and 13C{1H} NMR) are in accordance with the proposed
formulations (see the Experimental Section for details).
In particular, the 13C{1H} NMR spectra strongly support
the presence of an alkenyl-phosphonio chain showing
four low-field doublet resonances assigned to the Ru-
CR ((E)-13, δ 205.61 (2J CP ) 13.9 Hz) ppm; (E)-14, δ
206.52 (2J CP ) 12.0 Hz) ppm)), the Câ ((E)-13, δ 122.35
(J CP ) 84.2 Hz) ppm; (E)-14, δ 122.61 (J CP ) 84.2 Hz)
ppm)), the dC ((E)-13, δ 124.35 (2J CP ) 56.4 Hz) ppm;
(E)-14, δ 126.16 (2J CP ) 57.3 Hz) ppm)), and the dCH
((E)-13, δ 135.04 (3J CP ) 9.2 Hz) ppm; (E)-14, δ 137.75
(3J CP ) 8.3 Hz) ppm)) carbons.
(CH2)nCH2 (n ) 1, 2, 3, 4), containing hydrogen atoms
adjacent to the hydroxy group, react with indenyl-
ruthenium(II) complexes [RuCl(η5-C9H7)L2] (L ) PPh3;
L2 ) dppe) to give selectively alkenyl-vinylidene species
of the type C (see Scheme 4). The process involves the
initial formation of undetected π-alkyne and hydroxivi-
nylidene derivatives (A), which spontaneously dehy-
drate to generate the final alkenyl-vinylidene species.
Since allenylidene complexes B were never isolated, this
fact indicates that the formation of vinylidene species
C is thermodinamically favored.12e,l
With these precedents in mind, we wondered whether
the modification of the electronic properties of the metal
fragment would affect this reactivity. Thus, we explored
the reactions of the tetrafluoroborate adducts [Ru-
The formation of complexes (E)-13,14 can be easily
explained as the result of the regioselective nucleophilic
attack of PPh3 on the π-coordinated 1,3-enyne on
intermediates [Ru(η2-HCtCR′)(η5-1,2,3-R3C9H4)(CO)-
(FBF3)(η5-1,2,3-R3C9H4)(CO)(PR3)] (R ) Me, PR3
)

5182 Organometallics, Vol. 20, No. 24, 2001
Cadierno et al.
Sch em e 5
(PR3)][BF4] (R′ ) 1-cyclooctenyl). Nevertheless, an
alternative mechanism involving the initial formation
of alkenyl-phosphonio derivatives (E)-[Ru{C(H)dC-
(PPh3)R′}(η5-1,2,3-R3C9H4)(CO)(PR3)][BF4] (R′ ) cyclooc-
tyl-1-ol) followed by the spontaneous dehydration of the
cyclooctyl-1-ol moiety cannot be discarded.
Ru-P(1), C(1)-Ru-P(1), and C(1)-Ru-C(3); (EE)-12b,
P(1)-Ru-P(2), C(1)-Ru-P(1), and C(1)-Ru-P(2)) and
those between the centroid C* and the legs show values
typical of a pseudooctahedron (see captions for Figures
1 and 2). The most interesting features of the structures
are those related to the alkenyl-phosphonio ligands. An
E configuration for this moiety (the ruthenium atom is
located trans with respect to the triphenylphosphine
group) is in both cases observed. In accordance with the
NMR data, an E stereochemistry is also found for the
CHdCH unit in complex (EE)-12b. The dihedral angle
(DA) between the pseudo mirror plane of the metallic
moiety (containing the ruthenium atom, the C(1) atom,
and the centroid C* of the five-carbon ring of the indenyl
ligands) and the mean phosphonio-alkenyl plane (con-
taining the Ru, C(1), C(2) atoms) is 107.0(6) [(E)-7] and
100.7(6)° [(EE)-12b], showing a deviation from the
orthogonal relationship calculated by theoretical stud-
ies.15 The Ru-C(1) bond length ((E)-7, 2.039(7) Å; (EE)-
X-r a y Cr ysta l Str u ctu r es of (E)-[Ru {C(H)dC-
(P P h 3)P h }(η5-1,2,3-Me3C9H4)(CO)(P P h 3)][BF 4] a n d
(E E )-[R u {C(H )dC(P P h 3)CH dCH (η5-C5H 4)F e (η5-
C5H5)}(η5-C9H7)(P P h 3)2][BF 4]. Crystals of (E)-7 and
(EE)-12b suitable for X-ray diffraction analysis were
obtained by slow diffusion of hexane into saturated
solutions of the complexes in dichloromethane. The
crystal structure of (EE)-12b consists of one molecule
of the complex together with two CH2Cl2 molecules of
crystallization. ORTEP views of the molecular geom-
etries of (E)-7 and (EE)-12b are shown in Figures 1 and
2, respectively. Selected bond distances and angles are
listed in the captions. Both molecules exhibit the usual
pseudooctahedral three-legged piano stool geometry
with the corresponding indenyl ligand in the usual η5
coordination mode. The interligand angles ((E)-7, C(3)-
F igu r e 2. ORTEP view of the structure of the cation (EE)-
12b (thermal ellipsoids at 30% probability). Aryl groups
of the triphenylphosphine ligands have been omitted for
clarity (C* ) centroid of the indenyl ring). Selected bond
lengths (Å) and angles (deg): Ru1-C* ) 1.986(1); Ru1-
P1 ) 2.341(2); Ru1-P2 ) 2.315(3); Ru1-C1 ) 2.039(8);
C1-C2 ) 1.354(11); C2-P3 ) 1.783(8); C2-C3 ) 1.481-
(11); C3-C4 ) 1.334(12); C4-C81 ) 1.465(13); C*-Ru1-
P1) 123.78(6); C*-Ru1-P2 ) 119.47(8); C*-Ru1-C1 )
123.7(2); P1-Ru1-C1 ) 90.1(2); P2-Ru1-C1 ) 88.8(3);
P1-Ru1-P2 ) 102.70(10); Ru1-C1-C2 ) 133.5(7); C1-
C2-P3 ) 120.4(6); C1-C2-C3 ) 125.2(7); C2-C3-C4 )
130.4(8); C3-C4-C81 ) 121.7(9); Ru1-C1-H1 ) 113.2;
P3-C2-C3 ) 114.4(6).
F igu r e 1. ORTEP view of the structure of the cation (E)-7
(thermal ellipsoids at 30% probability). Aryl groups of the
triphenylphosphine ligands have been omitted for clarity
(C* ) centroid of the indenyl ring). Selected bond lengths
(Å) and angles (deg): Ru1-C* ) 1.953(5); Ru1-P1 ) 2.323-
(2); Ru1-C1 ) 2.039(7); Ru1-C3 ) 1.831(9); C3-O3 )
1.170(9); C1-C2 ) 1.344(10); C2-P2 ) 1.801(7); C2-C81
) 1.513(10); C*-Ru1-P1 ) 130.4(2); C*-Ru1-C1 ) 119.5-
(2); C*-Ru1-C3 ) 121.4(3); C3-Ru1-P1 ) 92.0(3); C1-
Ru1-P1 ) 86.7(2); C1-Ru1-C3 ) 97.8(3); Ru1-C1-C2
) 135.6(6); C1-C2-P2 ) 120.5(6); C1-C2-C81 ) 124.9-
(7); Ru1-C1-H1 ) 113.1.

Indenyl-Ruthenium(II) Vinylidene Reactivity
Organometallics, Vol. 20, No. 24, 2001 5183
12b, 2.039(8) Å) can be compared to that shown by the
analogous indenyl-ruthenium(II) alkenyl-phosphonio
complex (E)-[Ru{C(H)dC(PPh3)R}(η5-C9H7)(PPh3)2][PF6]
(R ) 1-cyclohexenyl; 2.045(6) Å),12e but is slightly
shorter than those reported for other alkenyl-ruthe-
nium(II) complexes, i.e., (E)-[Ru{C(CO2Me)dCH(CO2-
Me)}(η5-C5H5)(dppe)] (2.07(1) Å),16 (Z)-[Ru{C(CO2Me)d
CH(CO2Me)}(η5-C5H5)(CO)(PPh3)] (2.080(8) Å),16 (E)-
[Ru{C(H)dCH(R)}Cl(CO)(Me2Hpz)(PPh3)2] (R ) nPr
(2.05(1) Å),17 tBu (2.063(7) Å)18), (E)-[Ru{C(H)dCH(t-
Bu)}(CO){NHdC(Me)(Me2Hpz)}(PPh3)2][PF6] (2.067(8)
Å),19 and (E)-[Ru{C(H)dCH(Ph)}(CH3)(CO)2(PiPr3)2]
(2.141(3) Å).20 The C-C bond lengths of the dienyl chain
C(1)-C(4) in complex (EE)-12b are consistent with the
typical sequence of double, single, and double bonds, i.e.,
1.354(11), 1.481(11), and 1.334(12) Å, respectively.
Similarly, the C(1)-C(2) distance in complex (E)-7
(1.344(10) Å) shows also the expected value for a double
carbon-carbon bond.
Th eor etica l Ca lcu la tion s. The η2-alkyne to η1-
vinylidene tautomerization in the coordination sphere
of transition metals is at present well-documented by
theoretical studies which show that this process is
energetically favored.3a,d,e,6,21 When this transformation
takes place in d6 metal complexes, the [1,2]-H shift
mechanism has been found to be the most favored.3a In
a previous work we have reported a theoretical study
on the tautomerization of the indenyl-ruthenium(II)
complexes [Ru(η5-C9H7)(PH3)2(C2H2)]+ (C2H2 ) η2-HCt
CH, η1-dCdCH2).6 As previously mentioned, the re-
placement in the metallic fragment of one of the PPh3
ligands by CO seems to determine the tautomerization
control, since, as shown for the moieties [Ru(η5-1,2,3-
Me3C9H4)(CO)(PR3)]+ (L ) PPh3, PiPr3), the process
leads to an equilibrium of the η2-alkyne and the η1-
vinylidene complexes. To explain this behavior, we have
performed a DFT study of the two reaction paths using
as models the complexes [Ru(η5-C9H7)(PH3)L(C2H2)]+ (L
) CO, PH3). Geometry optimization and vibrational
analysis on the C2H2 unit with the [Ru(η5-C9H7)(PH3)L]+
moieties were performed. The optimized structures and
main geometric parameters are shown in Figures 3 (L
) CO) and 4 (L ) PH3), while their relative energies
are summarized in Figure 5.
F igu r e 3. Optimized ab initio (B3LYP) structures (Å, deg)
of reactants, products, and transition states for the forma-
tion of [Ru(η5-C9H7)(dCdCH2)(CO)(PH3)]+ from [Ru(η5-
C9H7)(CO)(PH3)]+ and C2H2.
F igu r e 4. Optimized ab initio (B3LYP) structures (Å, deg)
of reactants, products, and transition states for the forma-
tion of [Ru(η5-C9H7)(dCdCH2)(PH3)2]+ from [Ru(η5-C9H7)-
(PH3)2]+ and C2H2.
In the previous theoretical study on [Ru(η5-C9H7)-
(PH3)2(C2H2)]+, following Wakatsuki’s previous studies
on Ru(II) complexes,3a we have assumed that the 1,2-
hydrogen migration proceeds with Cs symmetry.6 How-
ever, in this work we have examined an alternative
process without restriction of symmetry which allows
us to compare the results with the model [Ru(η5-C9H7)-
(CO)(PH3)(C2H2)]+ in which the symmetry plane is not
present. Similar reaction paths were found (Figure 5)
in the potential energy surface for the two types of
complexes [Ru(η5-C9H7)(PH3)L(C2H2)]+ (L ) CO, PH3),
with five stationary points for each of them: three
minima A, C, and E and two transition states B and
D. The indenyl ligand is located in a trans orientation
relative to the η2-alkyne or vinylidene groups in agree-
ment with the preferred conformation found in our
reported theoretical and crystallographic studies.12a The
structure of the η2-alkyne complexes A and of the η1-
vinylidene complexes E, where the alkyne and vi-
nylidene groups are located perpendicular to the pseudo-
molecular plane (containing the ruthenium atom and
both indenyl centroids C* and C**) are more stable than
the corresponding rotamers, where both groups are
contained in the pseudomolecular plane.6 MO calcula-
tions reported earlier indicate that the most efficient
π-back-bonding from the metal to the π-alkyne or
(15) Kostic, N. M.; Fenske, R. J . Organometallics 1982, 1, 974.
(16) Bruce, M. I.; Catlow, A.; Humphrey, M. G.; Koutsantonis, G.
A.; Snow, M. R.; Tiekink, E. R. T. J . Organomet. Chem. 1988, 338, 59.
(17) Torres, M. R.; Santos, A.; Perales, A.; Ros, J . J . Organomet.
Chem. 1988, 353, 321.
(18) Romero, A.; Santos, A. Vegas, A. Organometallics 1988, 7, 1988.
(19) Lo´pez, J .; Santos, A.; Romero, A.; Echevarren, A. M. J . Orga-
nomet. Chem. 1993, 443, 221.
(20) Bohanna, C.; Esteruelas, M.; A.; Lahoz, F. J .; On˜ate, E.; Oro,
L. A. Organometallics 1995, 14, 4685.
(21) (a) Silvestre, J .; Hoffmann, R. Helv. Chim. Acta 1985, 68, 1461.
(b) Stegmann, R.; Frenking, G. Organometallics 1998, 17, 2089. (c)
Garc´ıa-Yebra, C.; Lo´pez-Mardomingo, C.; Fajardo, M.; Antin˜olo, A.;
Otero, A.; Rodr´ıguez, A.; Vallat, A.; Lucas, D.; Mugnier, Y.; Carbo´, J .
J .; Lledo´s, A.; Bo, C. Organometallics 2000, 19, 1749.

5184 Organometallics, Vol. 20, No. 24, 2001
Cadierno et al.
The transition states B and D connect the three
minima found in each reaction channel, giving rise to
the activation barrier of the two-step mechanism in-
volved in the 1,2-hydrogen migration. The species B lie
above complexes E at 29.3 (L ) CO) and 33.9 kcal/mol
(L ) PH3), only slightly destabilized from the intermedi-
ate energy values. The internal geometry parameters
of the C2H2 group in B do not significantly change with
respect to A, although the angle Ru-CR-Câ increases
from 74.7 (L ) CO) and 73.6° (L ) PH3) in the η2-alkyne
species to 137.7 and 128.9°, respectively, in the transi-
tion states. This is in agreement with a slippage of the
η2-CC alkyne complex to the η2-CH found in the
intermediates C. The species D, which are located at
the highest energies of the reaction path with values of
35.4 (L ) CO) and 40.2 kcal/mol (L ) PH3), are
generated as transition states in the migration of the
hydrogen atom from CR to Câ. For L ) CO there is a
lengthening of the Ru-HR distance and a shortening of
the Câ-HR distance with respect to the intermediate C
(2.534 vs 1.941 Å and 1.689 vs 2.209 Å, respectively).
Similar differences are found for the bis-phosphine
derivative (L ) PH3).
As far as the back and forth η1-vinylidene-η2-alkyne
tautomerization process is concerned, it is interesting
to note that the calculated activation energy for each
reaction path reveals higher values for the bis-phos-
phine complex: 25.3 and 35.4 kcal/mol (L ) CO) vs 27.7
and 40.2 kcal/mol (L ) PH3). These data, in addition to
the relative stability of the vinylidene tautomer with
respect to the η2-alkyne, which is lower for the carbo-
nyl-phosphine complex 10.11 (L ) CO) vs 12.52 kcal/
mol (L ) PH3), indicate that the vinylidene to alkyne
tautomerization is more accessible both thermodinami-
cally and kinetically for the carbonyl species. Although
the difference in the energy values is not critical, this
is in agreement with the experimental observations
which show that at room temperature an η2-alkyne-
η1-vinylidene equilibrium is only observed for the car-
bonyl derivatives.
F igu r e 5. Energy diagram (kcal/mol) for the formation of
[Ru(η5-C9H7)(dCdCH2)L(PH3)]+ (L ) CO, PH3) from [Ru-
(η5-C9H7)L(PH3)]+ and C2H2. To compare the energy values
for each case the origins have been fixed at 0.0 kcal/mol
for the vinylidene complexes.
vinylidene group is found for this orientation.15,22 X-ray
crystal structure determinations4b,12a,e of both complexes
are in agreement with these theoretical calculations.
Figures 3 and 4 show the geometrically optimized
structures and the main geometric parameters. In E,
the calculated bond distances Ru-CR (1.862 (L ) CO)
and 1.844 Å (L ) PH3)) and CR-Câ (1.303 (L ) CO) and
1.308 Å (L ) PH3)) are very close to those experimen-
tally determined by X-ray diffraction in the vinylidene
complexes [Ru{dCdC(R1)R2}(η5-C9H7)(PPh3)2]+ (R1
)
Me, R2 ) Me, 1-cyclohexenyl; R1 ) H, R2 ) Ph; the
average values are 1.834(5) and 1.290(6) Å, respective-
ly).12a,e,23 The calculated Ru-P (2.395 and 2.375 Å) and
Ru-C* (2.011 and 2.007 Å) bond lengths are also in
agreement with the observed values (average values,
2.364(3) and 1.97(1) Å, respectively).
It is noteworthy that the actual presence in the
i
complexes of PR3 (R ) Ph, Pr) instead of the PH3 used
in the models should increase the steric effects notably.
If this fact is considered, the calculations would lead to
(i) a higher stabilization of the vinylidene species with
respect to the η2-alkyne precursors for both cases,
because the former are less influenced by steric effects
caused by the presence of bulky phosphine ligands; and
(ii) due to the fact the structures of the species involved
in the reaction pathways show the C2H2 moiety near
the preferred perpendicular orientation, where this
position has greater steric hindrance, in particular for
the bis-phosphine complex, the energy profile of the
reaction paths must be higher than those calculated in
the absence of steric effects.
The calculated energies (Figure 5) indicate that the
vinylidene complexes E are the structures with a global
minimum energy. It is also found that the rearrange-
ment of A to E is an exothermic process, being slightly
more favored for the bis-phosphine than for the carbonyl
complex (12.5 vs 10.1 kcal/mol). In the reaction pathway,
which connects the η2-alkyne with the vinylidene com-
plexes, there have been located the structures of the
intermediates C at 28.9 (L ) CO) and 30.9 kcal/mol (L
) PH3) above the vinylidene complexes. The calculated
geometries of C shown in Figures 3 (L ) CO) and 4 (L
) PH3) display values for Ru-CR of 2.204 and 2.151 Å
and for Ru-HR of 1.941 and 1.832 Å, respectively. The
relative stabilization of the intermediate complexes C
with respect to species B seems to be a result of the
stronger σ-C-H metal bonding.3a,d,e,6,21,24
In conclusion, it is apparent that the substitution of
one PPh3 by a CO ligand has a greater effect on the
releasing of the steric hindrance in the η2-alkyne
coordination with respect to the bis-phosphine complex.
Nevertheless, the electronic effect is also operative, and
therefore the control of the tautomerization process will
be the result of both steric and electronic contribu-
tions.
(22) Kitaura, K.; Sakaki, S.; Morokuma, K. Inorg. Chem. 1981, 20,
2292.
(23) Pe´rez-Carren˜o, E. Doctoral Thesis, University of Oviedo, 1996.
(24) Oliva´n, M.; Clot, E.; Eisenstein, O.; Caulton, K. G. Organome-
tallics 1998, 17, 3091.

Indenyl-Ruthenium(II) Vinylidene Reactivity
Organometallics, Vol. 20, No. 24, 2001 5185
Discu ssion
12a -c, obtained by addition of PPh3 to the stable
alkenyl-vinylidene complexes 11a -c (Scheme 3) clearly
demonstrates that this nuceophilic addition is thermo-
dinamically favored since the process proceeds through
the transient formation of π-alkyne complexes. This is
consistent with our previous experimental and theoreti-
cal studies on the tautomerization of stable vinylidene
complexes [Ru{dCdC(H)R}(η5-C9H7)(PPh3)2]+ to the
corresponding π-alkyne derivatives.6,7 In accordance,
related nucleophilic additions on cationic iron(II) η2-
alkyne complexes [Fe(η2-RCtCR′)(η5-C5H5)(CO)L][BF4]
(L ) PPh3, P(OPh)3) have been reported to yield E-
alkenyl derivatives regioselectively.26 Although the nu-
cleophilic addition of phosphines to vinylidene com-
plexes to give R-phosphonio-alkenyl species [M]-C-
(PR3)dCR2 are scarce, probably on steric hindrance
grounds, several examples are known.27
The selectivity of the coordinated π-alkyne species for
undergoing nucleophilic addition of PPh3 is also achieved
for the equilibrium established in the activation of
1-ethynyl-1-cyclooctanol with the electrophilic ruthe-
nium precursors 1 and 2. Thus, the addition of PPh3,
as described above for the reactions with terminal
alkynes, gives also alkenyl-phosphonio complexes (E)-
13 and (E)-14 (Scheme 5). It is interesting to note that
the simple activation of the alkynol by 1 and 2, which
leads to an unidentified mixture of products, also
contrasts with the behavior shown by the ruthenium
derivatives [RuCl(η5-C9H7)L2] (L ) PPh3; L2 ) dppe),
which gives selectively alkenyl-vinylidene complexes
C (Scheme 4).12e,l Moreover, no allenylidene species are
apparently present in these reaction mixtures since
otherwise allenyl-phosphonio [Ru]-C(PPh3)dCdCR2 or
alkynyl-phosphonio complexes [Ru]-CtCC(PPh3)R2,
generated from the nucleophilic addition of PPh3 on the
electrophilic CR or Cγ atoms of the allenylidene chain,
respectively, would have to be formed.28 In fact, we have
reported that related allenylidene complexes [Ru{dCd
CdC(R)R′}(η5-C9H7)(PPh3)2][PF6] (R ) R′ ) Ph; R ) H,
The tautomerization of terminal alkynes HCtCR into
a vinylidene group dCdC(H)R in the presence of
transition metal complexes has been specially studied
for ruthenium(II) derivatives.1 It is nowadays well-
established both experimentally and theoretically that
the first step in the mechanism of this process involves
the formation of a π-alkyne ruthenium complex, which
in most cases undergoes a thermodinamically favored
transformation to the vinylidene complex.3 In this work
examples of the existence of an equilibrium mixture
involving both tautomers, i.e., between the η1-vi-
nylidenes 4a -c and the η2-alkynes 5a -c, are shown.
These equilibria are easily achieved from the classical
treatment of the chloride precursor complexes 1-3 with
AgBF4 in the presence of the terminal alkyne. This
behavior contrasts with that shown in analogous reac-
tions using the electron-rich complexes [RuCl(η5-C9H7)-
L2] (L ) PPh3; L2 ) dppe, dppm) which yield stable
vinylidene derivatives.12a,d,e,j,l This type of equilibrium
have been also observed in the activation of HCtCPh
with the related ruthenium fragment [Ru(η5-C5H5)(CO)-
(PPh3)]+ at room temperature10 and in the isomerization
of [Fe{dCdC(R)R′}(η5-C5H5)(CO)2)]+ (R ) R′ ) Me, Ph;
R ) Me, R′ ) Ph) to internal π-alkyne complexes [Fe-
(η2-RCtCR′)(η5-C5H5)(CO)2)]+ which is readily estab-
lished above -50 °C.25 All of these examples seem to
indicate that the conversion of η2-alkyne derivatives into
the corresponding η1-vinylidene tautomers depends
mainly on the electronic properties of the metal frag-
ment. However, we have found that along with the
electronic effect associated to the substitution of one
PPh3 by a more π-accepting CO ligand the η1-vi-
nylidene-η2-alkyne tautomerization process is also de-
pendent on the steric properties of both ligands.
The competitive reactivity toward nucleophiles of the
π-alkyne vs vinylidene complexes in these tautomer-
ization equilibria has been also studied. Thus, it has
been shown that the presence of the electrophilic
fragments [Ru(η5-1,2,3-R3C9H4)(CO)(PR3)] (R ) Me, PR3
) PPh3; R ) H, PR3 ) PiPr3) allows the nucleophilic
addition of PPh3 on the π-coordinated alkyne to give
selectively alkenyl-phosphonio complexes (E)-7 and
(E)-8 (Scheme 1). It is apparent that the selective
formation of these species is favored vs the potential
addition of the phosphine at the electrophilic CR atom
of the tautomeric vinylidene species.1 The synthesis of
the analogous alkenyl-phosphonio complexes (EE)-
(26) Reger, D. L. Acc. Chem. Res. 1988, 21, 229, and references
therein.
(27) Cationic iron(II) vinylidene complexes [Fe{dCdC(H)R}(η5-
C5H5)(CO)(PPh3)]+ react with phosphines to afford the R-phosphonio-
alkenyl derivatives [Fe{C(PR3)dC(H)R}(η5-C5H5)(CO)(PPh3)]+ (R ) H,
PR3 ) PPh3, PMe2Ph; R ) Ph, PR3 ) PPh3): (a) Kolobova, N. Y.;
Stripkin, V. V.; Alexandrof, G. G.; Struchkov, Y. T. J . Organomet.
Chem. 1979, 169, 293. (b) Boland-Lussier, B. E.; Churchill, M. R.;
Hughes, R. P.; Rheingold, A. L. Organometallics 1982, 1, 628. Similarly,
complexes [Re{C(PMe3)dCMe2}(η5-C5H5)(NO)(PPh3)]+ and [W{C-
(PPh3)dC(H)Ph}(η5-C5H5)(CO)3]+ have been obtained by addition of
the corresponding phosphine on vinylidenes [Re(dCdCMe2)(η5-C5H5)-
(NO)(PPh3)]+ and [W{dCdC(H)Ph}(η5-C5H5)(CO)3]+, respectively: (c)
Senn, D. R.; Wong, A.; Patton, A. T.; Marsi, M.; Strouse, C. E.; Gladysz,
J . A. J . Am. Chem. Soc. 1988, 110, 6096. (d) Kolobova, N. E.; Skripkin,
V. V.; Rozantseva, T. V. Izv. Akad. Nauk SSSR, Ser. Khim. 1979, 2393.
Neutral vinylidenes [Mn{dCdC(H)R}(η5-C5H5)(CO)2] also react with
phosphines to yield R-phosphonio-alkenyl complexes [Mn{C(PR3)d
C(H)R}(η5-C5H5)(CO)2] (PR3 ) PPh3, R ) Me, Ph, CtBu2OH.; PMe2Ph;
PR3 ) PMePh2, R ) Ph): (e) Antonova, A. B.; Kolobova, N. E.;
Petrovsky, P. V.; Lokshin, B. V.; Obezyuk, N. S. J . Organomet. Chem.
1977, 137, 55. (f) Nesmeyanov, A. N.; Kolobova, N. E.; Antonova, A.
B.; Obezyuk, N. S.; Anisimov, K. N. Izv. Akad. Nauk SSSR, Ser. Khim.
1976, 948. (g) Antonova, A. B.; Gubin, S. P.; Kovalenko, S. V. Izv. Akad.
Nauk SSSR, Ser. Khim. 1982, 953. The reaction of [W{dCdC(H)R}-
(η5-C5H5)(CO)(NO)] with Ph2PCl has been reported to yield metalla-
(25) (a) Bly, R. S.; Zhong, Z.; Kane, C.; Bly, R. K. Organometallics
1994, 13, 899, and references therein. Equilibriums between π-coor-
dinated terminal alkynes and their vinylidene tautomers have been
also proposed in Cr(CO)5 and W(CO)5 complexes. See for example: (b)
Abd-Alzaher, M. M.; Fischer, H. J . Organomet. Chem. 1999, 588, 235.
(c) Abd-Alzaher, M. M.; Froneck, T.; Roth, G.; Gvozdev, V.; Fischer,
H. J . Organomet. Chem. 2000, 599, 288, and references therein. The
spontaneous isomerization of [Nb{dCdC(H)R}(η5-C5H4SiMe3)2(CO)]+
(R ) Ph, tBu) into [Nb(η2-HCtCR)(η5-C5H4SiMe3)2(CO)]+ has been
recently reported: see ref 21c. The rearrangement of vinylidenes [M{d
CdC(R)SiMe3}(η5-C5H5)(CO)(NO)] (M) Mo, W; R ) Ph, tBu, Me, SiMe3)
into η2-alkyne complexes [M(η2-RCtCSiMe3)(η5-C5H5)(CO)(NO)] has
been also described: (d) Ipaktschi, J .; Demuth-Eberle, G. J .; Mirzaei,
F.; Mu¨ller, B. G.; Beck, J .; Serafin, M. Organometallics 1995, 14, 3335.
Vinylidene ligands in complexes [Re{dCdC(H)Ph}(CO)2P3]+ (P
)
cyclopropanes [WCl{CdC(H)R}(PPh2)(η5-C5H5)(NO)] (R ) H, Me, Ph)
by the nucleophilic attack of the phosphine on the CR carbon of the
vinylidene fragment: (h) Ipaktschi, J .; Klotzbach, T.; Du¨lmer, A.
Organometallics 2000, 19, 5281. The intramolecular version of a
phosphine attack at a vinylidene CR is also known. See for example:
(i) Bianchini, C.; Meli, A.; Peruzzini, M.; Zanobini, F.; Zanello, P.
Organometallics 1990, 9, 241.
P(OMe)3, PPh(OEt)2, PPh2OEt) and [OsX{dCdC(H)Ph}P4]+ (X ) Cl,
Br, I; P ) PPh(OEt)2, PPh2OEt) are rather labile the dissociation of
which gives the free alkyne: (e) Albertin, G.; Antoniutti, S.; Bordignon,
E.; Bresolin, D. J . Organomet. Chem. 2000, 609, 10. (f) Albertin, G.;
Antoniutti, S.; Bordignon, E.; Pegoraro, M. J . Chem. Soc., Dalton Trans.
2000, 3575.

5186 Organometallics, Vol. 20, No. 24, 2001
Cadierno et al.
one, Me-1, Me-2, and Me-3), 3.71 (s broad, 1H, HCt), 5.82-
R′ ) Ph; RR′ ) -CH2(CH2)nCH2-) readily react with
phosphines to afford cationic alkynyl-phosphonio de-
rivatives [Ru{CtCC(R)(PR3)R′}(η5-C9H7)(PPh3)2][PF6]
selectively.12e,f,j
7.80 (m, 24H, Ph, H-4, H-5, H-6, and H-7) ppm.
Syn th esis of [Ru (CtCP h )(η5-1,2,3-Me3C9H4)(CO)(P P h 3)]
(6). A mixture of 1 (0.628 g, 1 mmol) and AgBF4 (0.214 g, 1.1
mmol) in CH2Cl2 (50 mL) was stirred for 15 min at room
temperature in the absence of light. After the AgBr formed
was filtered, phenylacetylene (0.165 mL, 1.5 mmol) was added
to the solution. The reaction mixture was stirred for 5 min
and then treated with KOtBu (0.168 g, 1.5 mmol) at room
temperature for 40 min. The solvent was then evaporated in
vacuo and the resulting solid residue extracted with diethyl
ether (50 mL) and filtered. Evaporation of the diethyl ether
gave complex 6 as a yellow solid; yield, 75% (0.487 g). IR (KBr,
cm-1): 1935 ν(CO), 2093 ν(CtC). 31P{1H} NMR (C6D6): δ 54.78
(s) ppm. 1H NMR (C6D6): δ 1.53 and 2.04 (s, 3H each one, Me-
In summary, in this paper a systematic approach for
the selective synthesis of indenyl-ruthenium(II) alk-
enyl-phosphonio complexes is reported. It is shown by
theoretical calculations that the tautomerization equi-
librium between η2-alkyne and η1-vinylidene complexes
is dependent not only on the electronic properties but
also on the steric requirements of the ruthenium frag-
ment. The nucleophilic attack of PPh3 takes place
selectively on the coordinated π-alkyne molecule being
favored vs the addition at the electrophilic CR atom of
the corresponding η1-vinylidene tautomers.
4
1, Me-2, or Me-3), 1.94 (d, 3H, J HP ) 1.7 Hz, Me-1, Me-2, or
Me-3), 6.63, 6.71, and 6.82 (m, 1H each one, H-4, H-5, H-6, or
H-7), 6.96-7.40 (m, 21H, Ph and H-4, H-5, H-6, or H-7) ppm.
13C{1H} NMR (CD2Cl2): δ 8.59, 9.95, and 11.16 (s, Me-1, Me-
Exp er im en ta l Section
2
2, and Me-3), 85.56 (s, C-1 or C-3), 86.23 (d, J CP ) 5.0 Hz,
The manipulations were performed under an atmosphere
of dry nitrogen using vacuum-line and standard Schlenk
techniques. All reagents were obtained from commercial
suppliers and used without further purification. Solvents were
dried by standard methods and distilled under nitrogen before
use. The compounds 1, 3,9 2,9 11a ,6 (E)-11b,12j and (Z)-11c6
were prepared by following the methods reported in the
literature. Infrared spectra were recorded on a Perkin-Elmer
1720-XFT spectrometer. The conductivities were measured at
room temperature, in ca. 10-3 mol dm-3 acetone solutions, with
a J enway PCM3 conductimeter. The C and H analyses were
carried out with a Perkin-Elmer 240-B microanalyzer (uncom-
pleted combustions were systematically observed for most of
the complexes reported). Mass spectra (FAB) were recorded
using a VG Autospec spectrometer, operating in the positive
mode; 3-nitrobenzyl alcohol was used as the matrix. 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% H3PO4 as standards. DEPT experiments have been
carried out for all the complexes. The abbreviations used are
as follows: s, singlet; d, doublet; dd, doublet of doublets; t,
triplet; dt, doublet of triplets; m, multiplet.
C-1 or C-3), 105.24 and 109.01 (s, C-2, C-3a, or C-7a), 110.50
2
2
(d, J CP ) 8.1 Hz, C-2, C-3a, or C-7a), 109.87 (d, J CP ) 25.0
Hz, Ru-CR), 121.78-134.82 (m, Ph, Câ, C-4, C-5, C-6, and C-7),
2
207.25 (d, J CP) 18.6 Hz, CO) ppm. MS (FAB) for RuC39H33
-
OP: m/z 650 [M+], 622 [M+ - CO], 550 [M+ - CtCPh + 1],
522 [M+ - CtCPh - CO + 1], 465 [M+ - Me3C9H4 - CO].
Complex 6 was too sensitive to moisture and oxygen to give
satisfactory elemental analysis.
Syn th esis of (E)-[Ru {C(H)dC(P P h 3)R′}(η5-1,2,3-R3C9H4)-
(CO)(P R3)][BF 4] (R ) Me, P R3 ) P P h 3, R′ ) P h [(E)-7],
1-Cycloocten yl [(E)-13]; R ) H, P R3 ) P iP r 3, R′ ) P h [(E)-
8], 1-Cycloocten yl [(E)-14]). Gen er a l P r oced u r e. A mix-
ture of 1,2 (1 mmol) and AgBF4 (0.214 g, 1.1 mmol) in CH2Cl2
(100 mL) was stirred for 15 min at room temperature in the
absence of light. After the unsoluble salts formed were filtered,
the corresponding alkyne or 1-ethynyl-1-cyclooctanol (1.5
mmol) was added to the solution. The reaction mixture was
stirred for 10 min and then treated with PPh3 (0.262 g, 1 mmol)
at room temperature for 10 min. The solvent was then
evaporated in vacuo, and the resulting yellow solid washed
with diethyl ether (2 × 30 mL) and vacuum-dried. Yield (%),
IR (KBr, ν(CO), ν(BF4-), cm-1), conductivity (acetone, 20 °C,
The numbering for the indenyl skeleton is as follows:
Ω
1- cm2 mol-1), analytical data, NMR spectroscopic data, and
mass spectra are as follows. Compound (E)-7: 60 (0.599 g);
1937, 1055; 119. 31P{1H} (CDCl3): δ 16.70 (d, J PP ) 6.2 Hz,
4
C-PPh3), 52.82 (d, J PP ) 6.2 Hz, Ru-PPh3) ppm. 1H
4
(CDCl3): δ 1.52, 1.83, and 1.93 (s, 3H each one, Me-1, Me-2,
and Me-3), 6.67-7.78 (m, 39H, Ph, H-4, H-5, H-6, and H-7),
3
3
9.43 (dd, 1H, J HP ) 32.5 Hz, J HP ) 7.5 Hz, RuCH) ppm.
13C{1H} (CD2Cl2): δ 8.65, 9.99, and 10.74 (s, Me-1, Me-2, and
Me-3), 83.02 (d, J CP ) 3.7 Hz, C-1 or C-3), 88.16 (d, J CP
Sp ectr oscop ic Ch a r a cter iza tion of [Ru {dCdC(H)P h }-
(η5-1,2,3-Me3C9H4)(CO)(P P h 3)][BF 4] (4a ) a n d [Ru (η2-HCt
CP h )(η5-1,2,3-Me3C9H4)(CO)(P P h 3)][BF 4] (5a ). A mixture
of 1 (0.015 g, 0.024 mmol) and AgBF4 (0.005 g, 0.026 mmol) in
CD2Cl2 (0.6 mL) was stirred for 15 min at room temperature
in the absence of light. After the AgBr formed was filtered,
the solution was transferred into a NMR tube and pheny-
lacetylene (0.004 mL, 0.036 mmol) was then added at -60 °C.
The reaction was followed by 31P{1H} and 1H NMR spectros-
copy from -60 to +14 °C. The NMR data reported here were
obtained at -43 °C when a mixture of complexes 4a and 5a is
present in ca. ratio 1:1.3. Compound 4a . 31P{1H} NMR (CD2-
Cl2): δ 41.51 (s) ppm. 1H NMR (CD2Cl2): δ 1.17, 1.60, and
2.26 (s, 3H each one, Me-1, Me-2, and Me-3), 4.76 (s broad,
1H, RudCdCH), 5.82-7.80 (m, 24H, Ph, H-4, H-5, H-6, and
H-7) ppm. Compound 5a . 31P{1H} NMR (CD2Cl2): δ 44.65 (s)
ppm. 1H NMR (CD2Cl2): δ 1.41, 1.98, and 2.55 (s, 3H each
2
2
)
3.7 Hz, C-1 or C-3), 105.42, 110.65, and 112.91 (s, C-2, C-3a,
and C-7a), 119.53, 123.35, 125.74, and 127.80 (s, C-4, C-5, C-6,
and C-7), 121.28 (d, J CP ) 85.1 Hz, Câ), 128.74-139.82 (m,
Ph), 206.52 (dd, 2J CP ) 13.9 Hz, 2J CP ) 2.8 Hz, Ru-CR), 207.27
2
(d, J CP ) 17.6 Hz, CO) ppm. MS (FAB) for RuC57H49F4P2BO:
m/z 913 [M+], 651 [M+ - PPh3], 621 [M+ - Ph - CO -
Me3C9H4], 549 [M+ - C(H)dCPh(PPh3)], 521 [M+ - C(H)d
CPh(PPh3) - CO]. Compound (E)-8: 70 (0.598 g); 1941, 1056;
128. Anal. Calcd for RuC45H49F4P2BO: C, 63.16; H, 5.77.
4
Found: C, 61.61; H, 5.83. 31P{1H} (CDCl3): δ 16.15 (d, J PP
)
3.5 Hz, PPh3), 63.91 (d, 4J PP ) 3.5 Hz, PiPr3) ppm. 1H (CDCl3):
δ 0.73 (m, 9H, P(CHMeaMeb)3), 0.99 (m, 9H, P(CHMeaMeb)3),
1.77 (m, 3H, P(CHMeaMeb)3), 5.03, 5.44, and 5.68 (s, 1H each
one, H-1, H-2, and H-3), 6.97-7.79 (m, 24H, Ph, H-4, H-5, H-6,
and H-7), 9.85 (dd, 1H, J HP ) 30.9 Hz, J HP ) 8.3 Hz, RuCH)
ppm. 13C{1H} (CD2Cl2): δ 19.32 (s, P(CHMeaMeb)3), 19.54 (s,
P(CHMeaMeb)3), 27.70 (d, J CP ) 22.2 Hz, P(CHMeaMeb)3), 70.62
3
3
(28) For reviews on reactivity of allenylidene conplexes see: (a)
Werner, H. Chem. Commun. 1997, 903. (b) Touchard, D.; Dixneuf, P.
H. Coord. Chem. Rev. 1998, 178-180, 409. (c) Bruce, M. I. Chem. Rev.
1998, 98, 2797. (d) Cadierno, V.; Gamasa, M. P.; Gimeno, J . Eur. J .
Inorg. Chem. 2001, 571.
2
(d, J CP ) 4.6 Hz, C-1 or C-3), 71.22 (s, C-1 or C-3), 97.73 (s,
C-2), 111.26 and 111.55 (s, C-3a and C-7a), 120.41 and 122.10
(s, C-4, C-5, C-6, or C-7), 122.82-139.41 (m, Ph, Câ and

Indenyl-Ruthenium(II) Vinylidene Reactivity
Organometallics, Vol. 20, No. 24, 2001 5187
2
2
C-4, C-5, C-6, or C-7), 198.28 (dd, J CP ) 10.1 Hz, J CP ) 3.9
solvent was then evaporated in vacuo and the resulting yellow
solid washed with diethyl ether (3 × 20 mL) and vacuum-dried.
Yield (%), IR (KBr, ν(BF4-), cm-1), conductivity (acetone, 20
°C, Ω-1 cm2 mol-1), analytical, and NMR spectroscopic data
are as follows. Compound (E)-12a : 66 (0.854 g); 1048; 115.
Anal. Calcd for RuC79H64F4P3B: C, 73.32; H, 4.98. Found: C,
73.48; H, 4.81. 31P{1H} ((CD3)2CO): δ 23.55 (s broad, C-PPh3),
45.63 (s broad, Ru-PPh3) ppm. 1H ((CD3)2CO): δ 4.85 (s broad,
2H, H-1,3), 5.26 and 7.04 (m, 2H each one, H-4,7 and H-5,6),
5.92 (s broad, 1H, H-2), 6.85-7.89 (m, 56H, Ph and dCH),
10.88 (dt, 1H, 3J HP ) 33.6 Hz, 3J HP ) 9.9 Hz, RuCH) ppm. 13C-
{1H} ((CD3)2CO): δ 79.10 (s, C-1,3), 100.50 (s, C-2), 112.36 (s,
C-3a,7a), 121.06 (d, J CP ) 88.7 Hz, Câ), 124.11 (s, C-4,7 or
C-5,6), 124.87-136.23 (m, Ph, dCH, dC, and C-4,7 or C-5,6),
205.76 (m, Ru-CR) ppm. ∆δ(C-3a,7a) ) -18.34. Compound
2
Hz, Ru-CR), 207.14 (d, J CP ) 15.7 Hz, CO) ppm. ∆δ(C-3a,-
7a)) -19.29 (average). MS (FAB): m/z 769 [M+], 479 [M+
-
CO - PPh3], 405 [M+ - C(H)dCPh(PPh3)], 377 [M+ - C(H)d
CPh(PPh3) - CO], 319 [M+ - CO - PiPr3 - PPh3]. Compound
(E)-13: 60 (0.619 g); 1932, 1053; 96. Anal. Calcd for RuC59H57
-
F4P2BO: C, 68.67; H, 5.57. Found: C, 67.88; H, 4.72. 31P{1H}
4
4
(CDCl3): δ 15.84 (d, J PP ) 3.3 Hz, C-PPh3), 51.65 (d, J PP
)
3.3 Hz, Ru-PPh3) ppm. 1H (CDCl3): δ 0.65-2.14 (m, 10H,
CH2), 1.70 (s, 6H, Me-1, Me-2, or Me-3), 1.88 (s, 3H, Me-1, Me-
2, or Me-3), 2.67 (m, 2H, CH2), 5.41 (m, 1H, CdCH), 6.55-
3
7.81 (m, 34H, Ph, H-4, H-5, H-6, and H-7), 9.43 (dd, 1H, J HP
) 34.0 Hz, J HP ) 6.9 Hz, RuCH) ppm. 13C{1H} (CD2Cl2): δ
3
9.27, 9.71, and 10.76 (s, Me-1, Me-2, and Me-3), 25.79, 26.12,
27.57, 28.84, 28.90, and 29.50 (s, CH2), 84.19 (d, J CP ) 5.5
2
Hz, C-1 or C-3), 87.39 (s, C-1 or C-3), 107.66, 110.40, and
111.96 (s, C-2, C-3a, and C-7a), 120.43, 122.80, 126.20, and
127.21 (s, C-4, C-5, C-6, and C-7), 122.35 (d, J CP ) 84.2 Hz,
Câ), 124.35 (d, 2J CP ) 56.4 Hz, CdCH), 128.62-140.31 (m, Ph),
(EE)-12b: 68 (0.901 g); 1062; 118. Anal. Calcd for FeRuC77
-
H
64F4P3B: C, 69.74; H, 4.86. Found: C, 68.81; H, 4.94. 31P-
{1H} (CD2Cl2): δ 15.58 (s broad, C-PPh3), 48.24 (s broad, Ru-
PPh3) ppm. 1H (CD2Cl2): δ 3.89 (s, 5H, C5H5), 4.30 (m, 4H,
C5H4), 5.10 (s broad, 2H, H-1,3), 5.55 (m, 2H, H-4,7 or H-5,6),
5.64 (d, 1H, J HH ) 17.1 Hz, dCH), 5.82 (s broad, 1H, H-2),
6.97-7.83 (m, 48H, Ph, dCH and H-4,7 or H-5,6), 10.21 (dt,
1H, 3J HP ) 29.8 Hz, 3J HP ) 9.7 Hz, RuCH) ppm. 13C{1H} (CD2-
Cl2): δ 66.67 and 69.78 (s, CH of C5H4), 69.36 (s, C5H5), 73.54
(s, C-1,3), 84.06 (s, C of C5H4), 96.13 (s, C-2), 112.72 (s, C-3a,-
7a), 122.09 (d, J CP ) 85.1 Hz, Câ), 123.39 and 127.09 (s, C-4,7
and C-5,6), 128.36-137.44 (m, Ph and 2dCH), 212.36 (m, Ru-
CR) ppm. ∆δ(C-3a,7a) ) -17.98. Compound (EE)-12c: 73
(0.911 g); 1056; 128. Anal. Calcd for RuC74H62F4P3OB: C,
71.21; H, 5.00. Found: C, 70.75; H, 4.88. 31P{1H} (CD2Cl2): δ
3
2
135.04 (d, J CP ) 9.2 Hz, CdCH), 205.61 (d, J CP ) 13.9 Hz,
2
Ru-CR), 208.57 (d, J CP ) 19.4 Hz, CO) ppm. MS (FAB): m/z
945 [M+], 807 [M+ - CO - C8H13 - 1], 654 [M+ - CO - PPh3],
549 [M+ - C(H)dC(C8H13)(PPh3)], 521 [M+ - C(H)dC(C8H13)-
(PPh3) - CO]. Compound (E)-14: 50 (0.444 g); 1936, 1054; 118.
31P{1H} (CDCl3): δ 13.38 (d, J PP ) 3.6 Hz, PPh3), 64.11 (d,
4
4J PP ) 3.6 Hz, PiPr3) ppm. 1H (CDCl3): δ 0.78 (m, 9H,
P(CHMeaMeb)3), 0.94-2.18 (m, 24H, P(CHMeaMeb)3, P(CHMea-
Meb)3, and CH2), 5.38 and 5.66 (s broad, 1H, H-1, H-2, or H-3),
5.58 (m, 2H, CdCH and H-1, H-2, or H-3), 7.11-7.67 (m, 19H,
3
Ph, H-4, H-5, H-6, and H-7), 9.77 (dd, 1H, J HP ) 28.1 Hz,
3J HP ) 5.5 Hz, RuCH) ppm. 13C{1H} (CD2Cl2): δ 19.49-33.47
(m, P(CHMeaMeb)3, P(CHMeaMeb)3, P(CHMeaMeb)3 and CH2),
15.82 (s broad, C-PPh3), 48.17 (s broad, Ru-PPh3) ppm. H
1
((CD3)2CO): δ 3.80 (s, 3H, OCH3), 5.14 (s broad, 2H, H-1,3),
5.61 (m, 2H, H-4,7 or H-5,6), 5.92 (d, 1H, J HH ) 16.7 Hz, d
CH), 6.16 (s broad, 1H, H-2), 7.09-8.12 (m, 37H, Ph, C6H4,
2
2
70.83 (d, J CP ) 3.7 Hz, C-1 or C-3), 71.51 (d, J CP ) 1.8 Hz,
C-1 or C-3), 96.98 (s, C-2), 111.87 and 112.07 (s, C-3a and
C-7a), 122.61 (d, J CP) 84.2 Hz, Câ), 123.22 and 126.26 (s, C-4,
3
3
dCH and H-4,7 or H-5,6), 10.36 (dt, 1H, J HP ) 30.4 Hz, J HP
) 10.0 Hz, RuCH) ppm. 13C{1H} (CD2Cl2): δ 55.77 (s, OCH3),
73.51 (s, C-1,3), 96.41 (s, C-2), 112.90 (s, C-3a,7a), 114.69 (s,
CH of C6H4), 121.92 (d, J CP ) 85.0 Hz, Câ), 123.41 (s, C-4,7 or
C-5,6), 127.25-135.75 (m, Ph, 2)CH, CH of C6H4, C of C6H4
and C-4,7 or C-5,6), 159.68 (s, C of C6H4), 214.78 (m, Ru-CR)
ppm. ∆δ(C-3a,7a) ) -17.80.
2
C-5, C-6, or C-7), 126.16 (d, J CP ) 57.3 Hz, CdCH), 128.92-
140.00 (m, Ph and C-4, C-5, C-6, or C-7), 137.75 (d, 3J CP ) 8.3
Hz, CdCH), 206.52 (d, 2J CP ) 12.0 Hz, Ru-CR), 208.16 (d, 2J CP
) 12.0 Hz, CO) ppm. ∆δ(C-3a,7a) ) -18.73 (average). Com-
plexes (E)-7a and (E)-14 were too sensitive to moisture and
oxygen to give satisfactory elemental analyses.
Rea ction of [Ru I(η5-1,2,3-Me3C9H4)(CO)(P iP r 3)] w ith
P h en yla cetylen e a n d Tr ip h en ylp h osp h in e. A mixture of
3 (0.525 g, 1 mmol) and AgBF4 (0.214 g, 1.1 mmol) in CH2Cl2
(100 mL) was stirred for 15 min at room temperature in the
absence of light. After the AgI formed was filtered, pheny-
lacetylene (0.165 mL, 1.5 mmol) was added to the solution.
The reaction mixture was stirred for 10 min and then treated
with PPh3 (0.262 g, 1 mmol) at room temperature for 10 min.
The solvent was then evaporated in vacuo, and the resulting
yellow solid washed with diethyl ether (2 × 30 mL) and
vacuum-dried. IR, 31P{1H}, and 1H NMR spectroscopic data
are in agreement with the presence of a mixture of (E)-9 and
10 in ca. ratio 1:1.6. Compound (E)-9: IR (KBr, cm-1): 1928
X-r a y Diffr a ction Stu d ies. Data collection, crystal, and
refinement parameters for complexes (E)-7 and (EE)-12b are
collected in Table 1. A Mo KR radiation was used with a
graphite crystal monochromator on an Enraf-Nonius CAD4
single-crystal diffractometer (λ ) 0.71073 Å). The unit cell
parameters were obtained from the least-squares fit of 25
reflections (with θ between 15 and 18° for (E)-7 and between
6 and 13° for (EE)-12b). The intensity data were measured
with the ω-2θ scan technique and a variable scan rate, with
a maximum scan time of 60 s/reflection. The final drift
correction factors were between 0.98 and 1.05 for (E)-7 and
between 0.99 and 1.08 for (EE)-12b. On all reflections, profile
analysis was performed.29,30 Lorentz and polarization correc-
2
4
ν(CO), 1054 ν(BF4-). 31P{1H} (CDCl3): δ 15.54 (d, J PP ) 4.6
tions were applied, and the data were reduced to Fo values.
4
1
Hz, PPh3), 58.50 (d, J PP ) 4.6 Hz, PiPr3) ppm. H (CDCl3): δ
0.71-2.32 (m, 30H, P(CHMeaMeb)3, P(CHMeaMeb)3, P(CHMea-
Meb)3, Me-1, Me-2, and Me-3), 6.51-7.82 (m, 24H, Ph, H-4,
The structures were solved by Patterson methods using the
program DIRDIF.31 Isotropic least-squares refinement on F2
was made using SHELXL93.32 Hydrogen atoms were geo-
metrically placed. During the final stages of the refinement
the positional parameters and the anisotropic thermal param-
eters of the non-H-atoms were refined (except the high
disordered CH2Cl2 and BF4- molecules on (EE)-12b which were
3
3
H-5, H-6, and H-7), 10.20 (dd, 1H, J HP ) 32.6 Hz, J HP ) 5.0
Hz, RuCH) ppm. Compound 10: IR (KBr, cm-1): 1946 ν(CO),
1054 ν(BF4-). 31P{1H} (CDCl3): δ 44.01 (d, J PP ) 21.3 Hz,
2
2
PPh3), 53.20 (d, J PP ) 21.3 Hz, PiPr3) ppm. 1H (CDCl3): δ
0.71-2.32 (m, 30H, P(CHMeaMeb)3, P(CHMeaMeb)3, P(CHMea-
Meb)3, Me-1, Me-2, and Me-3), 6.51-7.82 (m, 19H, Ph, H-4,
H-5, H-6, and H-7) ppm.
Syn t h esis of (EE)-[R u {C(H )dC(P P h 3)CH dCR R ′}(η5-
C9H7)(P P h 3)2][BF 4] (R ) R′ ) P h [(E)-12a ]; R ) H, R′ )
(η5-C5H4)F e(η5-C5H5) [(EE)-12b], 4-OMe-C6H4 [(EE)-12c]).
Gen er a l P r oced u r e. A solution of the corresponding vinylvi-
nylidene complex 11a -c (1 mmol) and PPh3 (3.934 g, 15 mmol)
in MeOH (50 mL) was heated under reflux for 90 min. The
(29) Grant, D. F.; Gabe, E. J . J . Appl. Crystallogr. 1978, 11, 114.
(30) Lehman, M. S.; Larsen, F. K. Acta Crystallogr., Sect. A 1974,
30, 580.
(31) Beurkens, P. T.; Admiraal, G.; Beurkens, G.; Bosman, W. P.;
Garc´ıa-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
DIRDIF Program System; Technical Report; Crystallographic Labora-
tory, University of Nijmegen: Nijmegen, The Netherlands, 1992.
(32) Sheldrick, G. M. SHELXL93. In Crystallographic Computing
6; Flack, P., Parkanyi, P., Simon, K., Eds.; IUCr/Oxford University
Press: Oxford, U.K., 1993.

5188 Organometallics, Vol. 20, No. 24, 2001
Cadierno et al.
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p lexes (E)-7 a n d (EE)-12b
complex (E)-7 complex (EE)-12b
57H49BF4OP2Ru
empirical formula
fw
C
C77H64BF4FeP3Ru‚2CH2Cl2
999.78
293(2)
0.71073
1495.86
200(2)
0.71073
temp, K
wavelength, Å
cryst syst
space group
a, Å
monoclinic
monoclinic
P21/c
P21/n
15.145(2)
16.212(10)
b, Å
15.228(4)
23.551(16)
c, Å
20.986(5)
18.143(9)
â, deg
98.99(2)
4
4780.5(17)
1.389
0.451
2056
94.39(6)
4
6907(7)
1.436
0.708
3052
Z
V, Å3
D
calcd, g cm-3
µ, mm-1
F(000)
cryst size, mm
θ range, deg
index ranges for data collecn
0.33 × 0.30 × 0.13
0.36 × 0.33 × 0.20
1.36-24.97
1.42-25.97
17 e h e 17
0 e k e 18
19 e h e 19
0 e k e 29
0 e l e 24
0 e l e 22
no. of rflns measd
9086
13961
no. of indep rflns
refinement method
8380
13526
full-matrix least-squares on F2
8380/0/599
full-matrix least-squares on F2
13526/3/778
1.023
data/restraints/params
goodness-of-fit on F2
final R factors (I > 2σ(I))
final R factors (all data)
largest diff. peak and hole, e Å-3
1.003
R1 ) 0.0534, wR2 ) 0.1147
R1 ) 0.2164, wR2 ) 0.1569
0.594 and -1.069
R1 ) 0.0854, wR2 ) 0.2010
R1 ) 0.1781, wR2 ) 0.2529
0.982 and -0.866
isotropically refined). The hydrogen atoms were isotropically
framework of DFT at the B3LYP level.38 LANL2DZ effective
core potentials (quasi relativistic for the metal centers) were
used to replace the 28 innermost electrons of Ru, as well as
the 10 core electrons of P.39 The associated double ú basis set
of P atoms was augmented by a d function.40 The rest of the
atoms were represented by a 6-31G(d,p) basis set.41 PH3 and
indenyl hydrogen atoms were represented at the STO-3G
level.42 In our calculations we have replaced the PPh3 ligand
and the monosubtituted acetylene by PH3 and HCtCH,
respectively.
Full geometry optimization and frequency calculations were
performed without any symmetry constraints. The stationary
points were classified as a minimun or transition state
according to vibrational analysis. The transition-state struc-
tures were relaxed after introducing small perturbations to
ensure that they are actually connected to the corresponding
reactants and products.
refined with a common thermal parameter.
2
(a ) Com p lex (E)-7. The function minimized was [Σω(Fo
-
Fc2)2/Σω(Fo2)2]1/2, where ω ) 1/[σ2 (Fo2) + (0.0535P)2 + 5.0778P]
2
2
with σ(Fo
)
from counting statistics and P ) (max(Fo2,0) +
2Fc2)/3. The maximum shift-to-estimated ratio in the last full-
matrix least-squares cycle was 0.001. The final difference
Fourier map showed no peaks higher than 0.59 e Å-3 nor
deeper than -1.07 e Å-3
.
(b) Com p lex (EE)-12b. The function minimized was [Σω-
(Fo - Fc2)2/Σω(Fo2)2]1/2, where ω ) 1/[σ2(Fo2) + (0.1074P)2
+
2
2
2
10.32P] with σ(Fo
)
from counting statistics and P ) (max-
(Fo2,0) + 2Fc2)/3. The maximum shift-to-estimated ratio in the
last full-matrix least-squares cycle was 0.027. The final
difference Fourier map showed no peaks higher than 0.98 e
Å-3 nor deeper than -0.87 e Å-3
.
Atomic scattering factors were taken from International
Tables for X-ray Crystallography (1974).33 Geometrical calcu-
lations were made with PARST.34 The crystallographic plots
were drawn by EUCLID35 (for (E)-7) or PLATON36 (for (EE)-
12b). All calculations were performed at the University of
Oviedo on the Scientific Computer Center and X-ray group
VAX and DEC-ALPHA computers.
Ack n ow led gm en t. This work was supported by the
Ministerio de Educacio´n y Cultura of Spain (Projects
PB96-0558 and PQU2000-0219) and the EU (Human
Capital Mobility Program, Project ERBCHRXCT 940501).
C.G.-B. thanks the Fundacio´n para la Investigacio´n
Cient´ıfica y Te´cnica de Asturias (FICYT) for the award
of a Thesis grant.
Com p u ta tion a l Deta ils. Ab initio calculations were car-
ried out with the Gaussian 98 set of programs37 within the
Su p p or tin g In for m a tion Ava ila ble: Crystal structure
data for (E)-7 and (EE)-12b, including tables of atomic
parameters, anisotropic thermal parameters, bond distances,
and bond angles, and figures showing 13C{1H} NMR spectra
for complexes 6, (E)-7, (E)-8, (EE)-12b, (E)-13, and (E)-14 and
FAB spectra for complexes 6, (E)-7, (E)-8, and (E)-13. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(33) International Tables for X-ray Crystallography; Kynoch Press:
Birminghan, U.K., 1974; Vol. IV.
(34) Nardelli, M. Comput. Chem. 1983, 7, 95.
(35) Spek, A. L. The EUCLID Package. In Computational Crystal-
lography; Sayre, D., Ed.; Clarendon Press: Oxford, U.K., 1982; p 528.
(36) Spek, A. L. Acta Crystallogr., Sect. A 1990, 46, C34.
(37) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J . R.; Zakrzewski, V. G.; Montgomery, J . A.;
Stratmann, E.; Burant, J . C.; Dapprich, S.; Millam, J . M.; Daniels, A.
D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J .; Barone, V.;
Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.; Clifford,
S.; Ochterski, J .; Petersson, G. A.; Ayala, P. Y.; Cui, Q.; Morokuma,
K.; Malick, D. K.; Rabuk, A. D.; Raghavachari, K.; Foresman, J . B.;
Cioslowski, J .; Ortiz, J . V.; Baboul, A. G.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R. L.;
Fox, D. J .; Keith, T. A.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara,
A.; Gonzalez, C.; Challacombe, M.; Gill, P. M. W.; J ohnson, B. G.; Chen,
W.; Wong, M. W.; Andres, J . L.; Head-Gordon, M.; Replogle, E. S.;
Pople, J . A. Gaussian 98 (Revision A.7); Gaussian Inc.: Pittsburgh,
PA, 1998.
OM010308E
(38) Becke, A. D. J . Chem. Phys. 1993, 98, 5648.
(39) Hay, P. J .; Wadt, W. R. J . Chem. Phys. 1985, 82, 299.
(40) Ho¨llwarth, A.; Bo¨hme, M.; Dapprich, S.; Ehlers, A. W.; Gobbi,
A.; J onas, V.; Ko¨hler, K.; Stegmann, R.; Veldkamp, A.; Frenking, G.
Chem. Phys. Lett. 1993, 208, 237.
(41) Hariharan, P. C.; Pople, J . Theor. Chim. Acta 1973, 28, 213.
(42) Hehre, W. J .; Stewart, R. F.; Pople, J . A. J . Chem. Phys. 1969,
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