Kinetics and mechanism of nucleophilic substitutions on coordinated polyenes and polyenyls. 3.

5674

Organometallics 1998, 17, 5674-5688

Kin etics a n d Mech a n ism of Nu cleop h ilic Su bstitu tion s

on Coor d in a ted P olyen es a n d P olyen yls. 3.¹Activa tion of

η⁵-Cyclop en ta d ien yl Liga n d s tow a r d Nu cleop h ilic Atta ck

th r ou gh η⁵f η³Rin g Slip p a ge a n d a Com p a r ison w ith

Rea ction a t C₅H₄O in [Ru (η⁵-C₅H₅)(η⁴-C₅H₄O)(L)]⁺(L )

CH₃CN, P yr id in e, Th iou r ea )

Walter Simanko,^†Walter Tesch,^†Valentin N. Sapunov,^†Kurt Mereiter,^‡

Roland Schmid,^†and Karl Kirchner*^,†,§

Institute of Inorganic Chemistry and Institute of Mineralogy, Crystallography, and Structural

Chemistry, Technical University of Vienna, Getreidemarkt 9, A-1060 Vienna, Austria

J ohn Coddington and Scot Wherland*^,|

Department of Chemistry, Washington State University, Pullman, Washington 99164-4630

Received August 17, 1998

Complexes of the types [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)]₂(CF₃SO₃)₂(1) and [Ru(η⁵-C₅H₅)(η⁴-

C₅H₄O)(L)]CF₃SO₃(L ) CH₃CN (2), pyridine (3), thiourea (4)) react with tertiary phosphines

to give (i) 1,1′- (12) or (ii) 1,2-disubstituted ruthenocenes (13) depending primarily on the

basicity of the entering phosphine and the nature of L. Path i proceeds via the intermediacy

of [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(PR₃)]₂²⁺(5) and [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(PR₃)(L)]⁺(6-8); i.e., the

hapticity of the C₅H₅ligand is changed from η⁵to η³while forming an additional Ru-P

1

bond. The η³bonding mode was established by H and ¹³C{¹H} NMR spectroscopies. The

kinetics of these reactions were studied in detail, providing enthalpies and entropies of both

activation and reaction. The conversions to 6-8 are exothermic (∆H° ) -5.5 to -16.9 kcal

mol^-1) but entropically unfavorable (∆S° ) -44.8 to -19.0 cal K^-1mol^-1). The activation

parameters and rate constants vary little with the phosphine, suggesting a preequilibrium

between η⁵and η³species of the starting complexes where the latter reacts with the entering

phosphine in the rate-determining step. The new η³-C₅H₅complexes are, with the exception

of 5, fluxional in solution due to an intramolecular enantiomeric equilibrium likely proceeding

through a five-coordinate η¹-C₅H₅intermediate. Path ii proceeds via η³-cyclopentenoyl

complexes of the type [Ru(η⁵-C₅H₅)(η³-C₅H₄O-2-PR₃)(L)]⁺(9-11). Furthermore, 3 and 4 react

with small and basic phosphines PR₃) PMe₃and Me₂PCH₂PMe₂to give the half-sandwich

complexes [Ru(η⁵-C₅H₄OH)(PR₃)₂L]⁺(14, 15) together with free C₅H₄PR₃(16).

In tr od u ction

cationic 18-electron complexes [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)]₂

2+

(1) and [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)(L)]⁺(L ) CH₃CN (2),

pyridine (3), thiourea (4)) to give 1,1′-disubstituted

ruthenocenes [Ru(η⁵-C₅H₄PR₃)(η⁵-C₅H₄OH)]⁺(12) (paths

i and ii, Scheme 1) as well as the anticipated 1,2-

disubstituted ruthenocenes (13), formed via η³-cyclo-

pentenoyl complexes [Ru(η⁵-C₅H₅)(η³-C₅H₄O-PR₃)(L)]⁺

(path iii, Scheme 1).^1,3Scheme 1 gives an overview of

the reactions hitherto analyzed on a synthetic level.

Thus, 1 yields only 12 irrespective of the nature of the

phosphine, whereas complexes 2-4 give 13 as well.

Preliminary kinetic studies with PMe₃as the nucleo-

phile have shown¹that the formation of 12 is far more

complex than that of 13. In the initial step, PMe₃attacks

the metal center to give the η³-C₅H₅intermediate [Ru-

Nucleophilic attack at metal-coordinated ligands con-

stitutes one of the most useful procedures in synthetic

organic chemistry for obtaining new regio- and stereo-

selectively functionalized molecules. Such processes are

particularly facile if the metal center is coordinatively

saturated, substitutionally inert, and sufficiently electron-

deficient. For the ligands, nonconjugated and conjugated

olefins are among the most reactive substrates, while

aromatic ligands, in particular the cyclopentadienyl

anion, are among the least reactive.²It was thus a

surprise to find that tertiary phosphines react with the

^†Institute of Inorganic Chemistry.

^‡Institute of Mineralogy, Crystallography, and Structural Chem-

istry.

^§E-mail: kkirch@mail.zserv.tuwien.ac.at.

^|E-mail: scot_wherland@wsu.edu.

(3) (a) Kirchner, K.; Taube, H. J . Am. Chem. Soc. 1991, 113, 7039.

(b) Kirchner, K.; Mereiter, K.; Schmid, R.; Taube, H. Inorg. Chem. 1993,

32, 5553. (c) Kirchner, K.; Mereiter, K.; Mauthner, K.; Schmid, R. Inorg.

Chim. Acta 1994, 217, 203. (d) Simanko, W.; Vallant, T.; Mereiter, K.;

Schmid, R.; Kirchner, K.; Coddington, J .; Wherland, S. Inorg. Chem.

1996, 35, 5923.

(1) Part 2: Simanko, W.; Sapunov, V. N.; Schmid, R.; Kirchner, K.;

Wherland, S. Organometallics 1998, 17, 2391.

(2) Davies, S. G.; Green, M. L. H.; Mingos, D. M. P. Tetrahedron

1978, 34, 3047.

Publication on Web 12/01/1998

Activation of η⁵-Cyclopentadienyl Ligands

Organometallics, Vol. 17, No. 26, 1998 5675

Sch em e 1

Sch em e 2

(η³-C₅H₅)(η⁴-C₅H₄O)(PMe₃)(L)]⁺which then undergoes

an endo migration of PMe₃to give [Ru(η⁵-C₅H₄PMe₃)-

(η⁵-C₅H₄OH)]⁺(12a ) and/or free C₅H₄PMe₃together

with the half-sandwich complex [Ru(η⁵-C₅H₄OH)-

(PMe₃)₂L]⁺(14a , 15), depending on L (Schemes 1 and

2).^1,3

frequently as a mechanistic rationale for a number of

stoichiometric⁴and catalytic⁵organometallic reactions.

These include R- and â-hydrogen abstractions,^6,7pho-

tochemically induced C-H, Si-H, and C-C bond cleav-

ages,⁸cyclopentadienyl ligand transfers,⁹and ligand

(4) (a) Yan, X.; Cherenga, A. N.; Metzler, N.; Green, M. L. H. J .

Chem. Soc., Dalton Trans. 1997, 2091. (b) Green, J . C.; Parkin, R. P.

G.; Yan, X.; Haaland, A.; Scherer, W.; Tafipolsky, M. A. J . Chem. Soc.,

Dalton, Trans. 1997, 3219. (c) Butts, M. D.; Bergman, R. G. Organo-

metallics 1994, 13, 1899.

(5) Sigman, M. S.; Fatland, A. W.; Eaton, B. E. J . Am. Chem. Soc.

1998, 120, 5130.

The process of η⁵to η³ring slippage of η⁵-C₅H₅ligands

(possibly also η³to η¹ring slippage) is an appealing way

of activating C₅H₅systems toward nucleophilic attack.

The occurrence of η³intermediates appears to be of more

general importance. Such species have been postulated

5676 Organometallics, Vol. 17, No. 26, 1998

Simanko et al.

substitutions.¹⁰Unfortunately, the few reports dealing

with additions, substitutions, and migrations of nucleo-

philes onto the C₅H₅ligand do not allow definite

conclusions to be drawn regarding the involvement of

ring slippage.¹¹Herein we report the kinetics and

mechanism of nucleophilic addition and substitution

reactions of tertiary phosphines with 1-4. In particular,

we present kinetic and thermodynamic data for the

formation of the 1,1′-disubstituted products via revers-

ible formation of η³-C₅H₅intermediates (Scheme 2). In

addition, the facile and reversible η⁵to η³transforma-

tions to the novel η³-C₅H₅complexes [Ru(η³-C₅H₅)(η⁴-

Sch em e 3

C₅H₄O)(PR₃)]₂(5) and [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(PR₃)-

2+

(L)]⁺(6-8) have been studied by low-temperature NMR

spectroscopy. Our mechanistic investigations are sup-

ported by extended Hu¨ckel molecular orbital calcula-

tions. Further data on the reactions that lead to the 1,2-

disubstituted ruthenocenes are presented, and the

origin of the selectivity between the two ruthenocene

products is discussed.

< P{(2,4,6-OMe)₃C₆H₂}₃(11.02), while the bulkiness of

the phosphines, as expressed by their cone angles,¹³

increases in the order PMe₃(118°) < PPh₃(145°) < PCy₃

(170°) < P{(2,4,6-OMe)₃C₆H₂}₃(184°). Below -70 °C,

Resu lts a n d Discu ssion

Syn th eses a n d Sp ectr oscop ic Stu d ies. We have

previously shown that the dimeric complex [Ru(η⁵-

C₅H₅)(η⁴-C₅H₄O)]₂(CF₃SO₃)₂(1) reacts with tertiary

phosphines to give exclusively 1,1′-disubstituted ru-

thenocenes 12 in essentially quantitative yield (Scheme

1).³To detect and identify intermediates, this reaction

with the tertiary phosphines PMe₃, PCy₃, P{(2,4,6-

OMe)₃C₆H₂}₃, and PPh₃has been monitored by NMR

spectroscopy. These phosphines have been chosen since

they cover a large range of nucleophilicity and size. The

nucleophilicity is taken to increase in the order of

increasing pK_a¹²PPh₃(2.73) < PMe₃(8.65) < PCy₃(9.70)

the dimeric complexes [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(PR₃)]₂

2+

(5a -c) are formed quantitatively (Scheme 3), except for

the weakly nucleophilic PPh₃, for which about 70%

unreacted 1 was observed at equilibrium. Upon an

increase in the temperature above -70 °C, all of these

complexes are cleanly converted to complexes 12a ,e,f,g

with no other intermediates detectable. The identity of

5a -d has been unequivocally established by ¹H and ³¹P-

{¹H} NMR spectroscopies and in the case of 5a also by

¹³C{¹H} NMR spectroscopy. The ¹H NMR spectra of

5a -d are consistent with both the ketonic oxygen of the

C₅H₄O moiety and the phosphine attached at the metal

center; i.e., the complex is both dimeric and chiral.

Complexes 5 are not fluxional (vide infra), and conse-

quently, in the ¹H NMR spectrum the protons of the

C₅H₅and C₅H₄O ligands give rise to nine individual

resonances. The ¹³C{¹H} NMR spectrum of 5a exhibits

altogether 10 individual resonances for the C₅H₅and

C₅H₄O ligands. The resonance of the “ketonic” carbonyl

carbon at 166.3 ppm is high-field shifted with respect

to the corresponding resonance in 1 (cf. 183.3 ppm in

1), indicating that the C₅H₄O ligand has become some-

what more electron rich (partially reduced). Note that,

for the final products 12, where the η⁴-bound cyclopen-

tadienone ligand is already fully reduced to an η⁵-bound

hydroxycyclopentadienyl system, the resonance of the

C-O carbon atom is found in the range 127-129 ppm.

Surprisingly, the dimeric nature of 5 is maintained

even if 1 is treated with the strongly basic bidentate

ligand Me₂PCH₂PMe₂. Instead of the expected mono-

meric complex [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(η²(P,P)-Me₂PCH₂-

PMe₂)]CF₃SO₃, the dimeric complex [Ru(η³-C₅H₅)(η⁴-

C₅H₄O)(η¹(P)-Me₂PCH₂PMe₂)]₂(CF₃SO₃)₂(5e) is obtained

with the Me₂PCH₂PMe₂ligand coordinated in η¹(P)-

fashion (cf. Scheme 4). Due to the η¹(P) coordination

mode of the Me₂PCH₂PMe₂ligand, in the ³¹P{¹H} NMR

spectrum the resonance of the coordinated PMe₂group

is significantly downfield shifted with respect to the

noncoordinated PMe₂moiety, giving rise to a doublet

(6) (a) Marks, T. J .; Kolb, J . R. J . Am. Chem. Soc. 1975, 97, 3397.

(b) Brintzinger, H. H.; Bercaw, J . E. J . Am. Chem. Soc. 1970, 92, 3397.

(c) Slocum, D. W.; Beach, D. L.; Ernst, C. R.; Fellows, R.; Moronski,

M.; Conway, B.; Bencini, J .; Siegel, A. J . Chem. Soc., Chem. Commun.

1980, 1043. (d) Roman, E.; Astruc, D.; Des Abbayes, H. J . Organomet.

Chem. 1981, 219, 211. (e) Slocum, D. W.; Engelmann, T. R.; Fellows,

R. L.; Moronski, M. Duraj, S. J . Organomet. Chem. 1984, 260, C21. (f)

Slocum, D. W.; Moronski, M.; Gooding, R.; Duraj, S. J . Organomet.

Chem. 1984, 260, C26.

(7) Yang, G. K.; Bergman, R. G. Organometallics 1985, 4, 129.

(8) (a) Green, M. L. H.; Berry, M.; Couldwell, C.; Prout, K. Nouv. J .

Chim. 1977, 1950. (b) Berry, M.; Elmitt, K.; Green, M. L. H. J . Chem.

Soc., Dalton Trans. 1979, 1950. (c) Ephritikhine, M.; Green, M. L. H.

J . Chem. Soc., Chem. Commun. 1976, 926. (d) Rest, A. J .; Whitwell,

I.; Graham, W. A. G.; Hoyano, J . K.; McMaster, A. D. J . Chem. Soc.,

Chem. Commun. 1984, 624. (e) Yang, H.; Kotz, K. T.; Asplund, M. C.;

Harris, C. B. J . Am. Chem. Soc. 1997, 119, 9564.

(9) (a) Peng, M. H.; Brubaker, C. H., J r. J . Organomet. Chem. 1977,

135, 333. (b) Lee, J . G.-S.; Brubaker, C. H., J r. Inorg. Chim. Acta 1977,

25, 181.

(10) (a) Vest, P.; Anhaus, J .; Bajaj, H. C.; van Eldik, R. Organome-

tallics 1991, 10, 818. (b) Rerek, M. E.; Basolo, F. J . Am. Chem. Soc.

1984, 106, 5908. (c) Cramer, R.; Seiwell, L. P. J . Organomet. Chem.

1975, 92, 245.

(11) (a) Arif, A. M.; Cowley, A. H.; Nunn, C. M.; Pakulski, M. J .

Chem. Soc., Chem. Commun. 1987, 994. (b) Benfield, F. W. S.; Green,

M. L. H. J . Chem. Soc., Dalton Trans. 1974, 1324. (c) Forschner, T.

C.; Cooper, N. J . J . Am. Chem. Soc. 1989, 111, 7420. (d) McNally, J .

M.; Cooper, N. J . J . Am. Chem. Soc. 1989, 111, 4500. (e) Hughes, R.

P.; Maddock; S. M.; Rheingold, A. L.; Liable-Sands, L. M. J . Am. Chem.

Soc. 1997, 119, 5988. (f) Herber, U.; Bleuel, E.; Gevert, O.; Laubender,

M.; Werner, H. Organometallics 1998, 17, 10. (g) de Azevedo, C. G.;

Calhorda, M. J .; Carrondo, M. A. A. F. d. C. T.; Dias, A. R.; Duarte, M.

T.; Galva˜o, A. M.; Gamelas, C. A.; Gonc¸alves, I. S.; da Piedade, F. M.;

Roma˜o, C. C. J . Organomet. Chem. 1997, 544, 257.

(12) (a) Golovin, M. N.; Rahman, Md. M.; Belemonte, J . E.; Giering,

W. P. Organometallics 1985, 4, 1981. (b) Bush, R. C.; Angelici, R. J .

Inorg. Chem. 1988, 27, 681. (c) Chenm, L.; Poe¨, A. J . Coord. Chem.

Rev. 1995, 143, 265.

(13) Tolman, C. A. Chem. Rev. 1977, 77, 313.

Activation of η⁵-Cyclopentadienyl Ligands

Organometallics, Vol. 17, No. 26, 1998 5677

(η³-C₅H₅)(η⁴-C₅H₄O)(η²(P,P)-Me₂PCH₂PMe₂)]CF₃SO₃and

[Ru(η³-C₅H₅)(η⁴-C₅H₄O)(η²(P,P)-Me₂PCH₂CH₂PMe₂)]CF₃-

SO₃, respectively, but instead gives [Ru(η³-C₅H₅)(η⁴-

C₅H₄O)(η¹(P)-Me₂PCH₂PMe₂)(CH₃CN)]CF₃SO₃(6e) and

[Ru(η³-C₅H₅)(η⁴-C₅H₄O)(η¹(P)-Me₂PCH₂CH₂PMe₂)(CH₃-

CN)]CF₃SO₃(6f) with the phosphine ligands bound in

an η¹(P)-fashion (Scheme 4). Similarly to 2, but at higher

temperatures (e-20 °C), [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)(py)]CF₃-

SO₃(3) reacts with PR₃(PMe₃, PBuⁿ₃, PMe₂Ph, or PCy₃)

to yield quantitatively [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(PR₃)-

(py)]CF₃SO₃(7a-d) (Scheme 2). Complexes 7 are formed

quantitatively even at room temperature but are un-

stable under this condition, being readily converted to

complexes 13a -c and 13f.^3dThis reaction proceeds via

the intermediacy of the η³-cyclopentenoyl complexes

[Ru(η⁵-C₅H₅)(η³-C₅H₄O-PR₃)(py)]CF₃SO₃(10).³Com-

plex 7a reacts in a less selective way to give a mixture

of 12a and 13a . With the phosphines PMePh₂and PPh₃,

no reaction takes place at low temperature. At ambient

temperature, PMePh₂reacts with 3 to yield quantita-

tively 13d . This reaction proceeds via the η³-cyclopen-

tenoyl complex 10d . The strongly basic chelating bis-

(phosphines) Me₂PCH₂PMe₂and Me₂PCH₂CH₂PMe₂, on

the other hand, react with 2 to give complexes of the

Sch em e 4

centered at 29.5 ppm (²J _PP) 35.9 Hz). The signal of

the noncoordinated PMe₂moiety exhibits a doublet

centered at -43.4 ppm (²J _PP) 35.9 Hz).

The monomeric complex [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)(CH₃-

CN)]CF₃SO₃(2) reacts with PR₃(PMe₃, PBuⁿ₃, PMe₂-

Ph) in acetone at -90 °C to afford the complexes [Ru(η³-

C₅H₅)(η⁴-C₅H₄O) (PR₃)(CH₃CN)]CF₃SO₃(6a-c) in quanti-

tative yield (Scheme 2). Upon an increase in the tem-

perature, complexes 6a -c are quantitatively converted

to complexes 12a -c. In the course of this reaction, no

other intermediates could be detected. The reaction of

2 with PMePh₂is less selective, as revealed by ¹H NMR

spectroscopy. At -90 °C, two competing reactions take

place to give the complexes [Ru(η³-C₅H₅)(η⁴-C₅H₄O)-

(PMePh₂)(CH₃CN)]CF₃SO₃(6d ) and [Ru(η⁵-C₅H₅)(η³-

C₅H₄O-PMePh₂) (CH₃CN)]CF₃SO₃(9a ) in a 1.3:1 ratio

with complete consumption of 2. At higher tempera-

tures, 9a and 6d (6d via the intermediacy of 2 and 9a )

are cleanly converted to the 1,2-disubstituted ru-

thenocene [Ru(η⁵-C₅H₅)(η⁵-C₅H₃OH-2-PMePh₂)]CF₃SO₃

(13d ) with no evidence found for the formation of the

1,1′-disubstituted ruthenocene [Ru(η⁵-C₅H₄PMePh₂)(η⁵-

C₅H₄OH)]CF₃SO₃(12d ) (Scheme 2). It is noteworthy

that, at low temperature, 2 does not react with PPh₃,

while, at ambient temperature, [Ru(η⁵-C₅H₅)(η⁵-C₅H₃-

OH-2-PPh₃)]CF₃SO₃(13e) is exclusively formed. In the

case of the bulky phosphine P{(2,4,6-OMe)₃C₆H₂}₃, no

evidence for the formation of an η³-C₅H₅complex is

found even at -90 °C, and the 1,2-disubstituted ru-

thenocene [Ru(η⁵-C₅H₅)(η⁵-C₅H₃OH-2-P{(2,4,6-OMe)₃-

C₆H₂}₃)]CF₃SO₃(13g) is formed exclusively.

type

[Ru(η³-C₅H₅)(η⁴-C₅H₄O)(η¹(P)-Me₂PCH₂PMe₂)-

(py)]CF₃SO₃(7e) and [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(η¹(P)-Me₂-

PCH₂CH₂PMe₂)(py)]CF₃SO₃(7f), respectively (Scheme

4).

Interestingly, in the presence of >2 equiv of PMe₃,

an alternative mode of reaction, which again is highly

selective, is observed. Complex 7a is slowly converted

to the half-sandwich complex [Ru(η⁵-C₅H₄OH)(PMe₃)₂-

(py)]CF₃SO₃(14a ) and free C₅H₄PMe₃(16a )¹⁴in es-

sentially quantitative yield as monitored by ¹H, ¹³C{¹H},

and ³¹P{¹H} NMR spectroscopies. The same reaction

occurs with Me₂PCH₂PMe₂, leading to the formation of

[Ru(η⁵-C₅H₄OH)(η²(P,P)-Me₂PCH₂PMe₂)(py)]CF₃SO₃

(14b) and free C₅H₄PMe₂CH₂PMe₂(16b). This pathway,

however, was not observed even with PBuⁿand thus

3

appears to be limited to phosphines with small cone

angles.

Attempts to isolate 7 in pure form usually failed due

to equilibria with other species. However, addition of

PMe₃to a solution of 3 in acetone afforded 7a as a pale

yellow solid in essentially quantitative yield due to its

insolubility in this solvent. In the solid state, 7a can be

handled for a short period of time. The IR spectrum of

7a exhibits a strong CdO stretching frequency at 1593

cm^-1(cf. 1682 cm^-1for 3¹⁵and 1709 cm^-1for free

C₅H₄O¹⁶) indicating loss of π-electron density from this

group to the ring and metal and, thus, a substantial

decrease in bond order. This observation suggests that

in complexes containing the [Ru(η³-C₅H₅)(η⁴-C₅H₄O)]⁺

moiety, there is a strong resonance interaction with the

carbonyl group leading to the limiting structure II.

Thus, the loss of aromaticity of the C₅H₅ring as a result

of the η⁵f η³ring slippage process may be partially

compensated for by the aromaticity gain of the C₅H₄O

ring, a ground-state effect, although the crystal struc-

The H and ¹³C{¹H} NMR spectra of 6 are consistent

1

with binding of the cyclopentadienyl ligand in an η³-

fashion. In the ¹H NMR spectra of 6, the olefinic

hydrogens H^3,4absorb at about 5.6 ppm, the terminal

allylic hydrogen atoms H^2,5absorb at about 3.8 ppm,

and the central allyl hydrogen H¹absorbs at about 4.4

ppm. Complexes 6 are chiral. In contrast to 5, complex

6 is fluxional in solution, and thus, the η³-C₅H₅ligand

exhibits only three proton and carbon resonances (in a

2:1:2 ratio) and the C₅H₄O ring shows only two hydrogen

and three carbon resonances. This process is in the fast

1

exchange region for 250 MHz H NMR, even at -90 °C

(14) Ladipo, F. T.; Anderson, G. K.; Rath, N. P. Organometallics

1994, 13, 4741.

(15) Kirchner, K.; Taube, H.; Scott, B.; Willett, R. D. Inorg. Chem.

1993, 32, 1430.

(16) Chapman, O. L.; McIntosh, C. L. J . Chem. Soc., Chem. Com-

mun. 1971, 770.

in acetone-d₆. Even though 6 is fluxional, the CH₃CN

ligand is substitutionally inert (vide infra). Accordingly,

the reaction of 2 with either Me₂PCH₂PMe₂or Me₂-

PCH₂CH₂PMe₂does not lead to the formation of [Ru-

5678 Organometallics, Vol. 17, No. 26, 1998

Simanko et al.

tures of 1-4¹⁵(Figures 1 and 2) show the C₅H₄O ring

to be nonplanar and folded away from Ru by 13.7, 18.0,

18.8, and 18.9°, respectively. The identities of the

1

intermediates 7 were established by H, ¹³C{¹H}, and

³¹P{¹H} NMR spectroscopies and in the case of 7a also

by elemental analysis. Complexes 7 are also fluxional

in solution with the overall NMR spectroscopic features

similar to those of 6 excepting the resonance of the

hydrogen atom H¹. The latter experiences a shift of

about -1.1 ppm relative to that of the analogous

complexes 6 due to anisotropic shielding by the aromatic

ring current of the pyridine placing the η³-C₅H₅ligand

in an endo orientation (as drawn in the schemes). Only

in this conformation is H¹situated above the pyridine

ring.

F igu r e 1. Structural view of [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)-

-

(py)]CF₃SO₃(3) showing 20% thermal ellipsoids (CF₃SO₃

omitted for clarity). Selected bond lengths (Å): Ru-

C(1-5)_av2.187(4), Ru-C(7) 2.240(3), Ru-C(8) 2.162(3),

Ru-C(9) 2.159(3), Ru-C(10) 2.237(4), Ru-N 2.127(3),

C(7)-C(8) 1.392(5), C(8)-C(9) 1.410(5), C(9)-C(10)

1.390(5), O(1)-C(6) 1.221(4).

Likewise, [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)(tu)]CF₃SO₃(4) is

found to react with PMe₃, PBuⁿ₃, PMe₂Ph, Me₂PCH₂-

PMe₂, and Me₂PCH₂CH₂PMe₂to yield the respective

complexes [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(PR₃)(tu)]CF₃SO₃(8a-

e) in quantitative yield as monitored by NMR spectros-

copy (Scheme 2). In the case of PMePh₂and PPh₃, no

reaction takes place at low temperatures. When the

temperature is raised, PMePh₂is converted to the η³-

cyclopentenoyl complex 11d . In the further course of

reaction, however, 11d decomposes to several intrac-

table materials. The NMR spectra of complexes 8a -e are

similar to those of 6 and 7 and are not discussed here.

It is interesting to note, however, that in contrast to the

cases of 6 and 7, when the temperature is lowered below

about 0 °C, the signals of H^2,5, H^3,4, H^6,9, and H^7,8

broaden and eventually reemerge as eight distinct

signals defining 8 as a chiral metal complex. The signal

of the allylic proton H¹remains unaffected by the

exchange process, thus arguing against an exo/endo

equilibrium. The same conclusion is drawn from ¹³C-

{¹H} NMR spectroscopy. This has been demonstrated

previously for 8a .¹The dynamic behavior of complexes

6-8 has been rationalized by an intramolecular enan-

tiomeric equilibrium leading to an inversion of ruthe-

nium as shown in Scheme 5. Site exchange by a

dissociative process is excluded by the observation that

the temperature dependence of the line shapes is

unaffected by addition of thiourea or PMe₃. From the

variable-temperature NMR studies, exchange rate con-

stants were determined by visual comparison of the

observed and computer-simulated spectra.¹⁷The rate

constants derived from the different sets of coalescing

resonances gave the same activation parameters. This

points to the operation of a single exchange mechanism

with ∆H^q) 12.3 ( 0.4 kcal mol^-1and ∆S^q) -0.3 ( 1.3

cal mol^-1K^-1. The rate constant (extrapolated to 298

K) of 5080 s^-1is about 2500 times greater than k_2min

Table 1, again signaling the absence of ligand dissocia-

tion in the enantiomeric conversion. Further support of

F igu r e 2. Structural view of [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)-

(tu)]CF₃SO₃‚CH₃CN (4‚CH₃CN) showing 20% thermal

-

ellipsoids (CF₃SO₃and CH₃CN omitted for clarity).

Selected bond lengths (Å) and angle (deg): Ru-C(1-5)_av

2.207(4), Ru-C(7) 2.259(2), Ru-C(8) 2.160(3), Ru-C(9)

2.151(3), Ru-C(10) 2.249(2), C(7)-C(8) 1.394(4), C(8)-C(9)

1.426(5), C(9)-C(10) 1.407(4), Ru-S(1) 2.399(1), O(1)-C(6)

1.229(3); Ru-S(1)-C(11) 110.6(1).

Sch em e 5

this interpretation follows from the observations that

the dimer 5 is not dynamic in nature and that in the

intermediates of Scheme 4 the ligand L is nonlabile. An

intramolecular isomerization process requires a vacant

coordination site with appropriate orbital geometry

which may be brought about by rearranging 6-8 toward

a five-coordinate pseudo four-legged piano stool complex

containing an η¹-C₅H₅ligand (as drawn in Scheme 5)

where the ligands L and PR₃change their positions in

a pseudorotational fashion.¹⁸For comparison, the acti-

vation enthalpies for such intramolecular ligand rear-

(17) (a) Binsch, G.; Kleier, D. DNMR3, Program 165; QCPE, Indiana

University: Bloomington, IN, 1970. (b) Binsch, G.; Kessler, H. Angew.

Chem. 1980, 92, 445.

(18) Galindo, A.; Mealli, C. Inorg. Chem. 1996, 35, 2406.

Activation of η⁵-Cyclopentadienyl Ligands

Organometallics, Vol. 17, No. 26, 1998 5679

Ta ble 1. Activa tion P a r a m eter a n d Ra te Con sta n t Da ta a t 25 °C for th e Rea ction s of

[Ru (η⁵-C₅H₅)(η⁴-C₅H₄O)(L)]CF ₃SO₃(L ) CH₃CN (2), P yr id in e (3), Th iou r ea (4)) w ith Ter tia r y P h osp h in es in

Aceton e To Give [Ru (η⁵-C₅H₄P R₃)(η⁵-C₅H₄OH)] (12) via [Ru (η³-C₅H₅)(η⁴-C₅H₄O)(P R₃)(L)]⁺(6, 7, or 8)

CH₃CN

pyridine

thiourea

PR₃pK_a;

cone angle,

deg^c

TTP^a

11.0; 184

PMe₃

PPrⁿ

PBuⁿ

PMe₂Ph

6.50; 122

PMePh₂

4.57; 136

PMe₃

PBuⁿ

PMe₂Ph

6.50; 122

PMe₃

b

3

8.65; 118

8.65; 1³31

8.43; 132

8.65; 118

8.43; 132

8.65; 118

q d

∆H_1m

∆S_1m

k

4.9 ( 0.2

4.8 ( 0.1

5.7 ( 0.2

5.1 ( 0.4

8.5 ( 0.1

6.5 ( 0.2

6.3 ( 0.1

10.4 ( 0.3

7.5 ( 1.2

q e

-27.8 ( 0.6 -30.2 ( 0.4 -26.3 ( 0.5 -29.2 ( 1.4 -18.2 ( 0.4 -24.8 ( 0.7 -27.5 ( 0.4 -13.0 ( 1.2 -26.5 ( 4.0

_1m, M^-1s^-1

1400

494

756

484

418

420

149

206

33

q

∆H_2m

∆S_2m

k

20.1 ( 1.0

9.8 ( 3.1

1.4

21.7 ( 1.8

14.6 ( 5.9

1.2

19.6 ( 0.8

9.9 ( 2.6

3.8

19.1 ( 0.8

11.0 ( 2.7

15.4

14.0 ( 0.1

0.9 ( 0.6

546

22.8 ( 1.2

18.4 ( 3.7

1.2

17.0 ( 1.5

4.4 ( 5.3

20

19.1 ( 0.3

16.2 ( 1.1

207

20.2 ( 2.6

10.8 ( 8.9

2

q

_2m, s^-1

∆H_m

°

-8.6 ( 0.3 -15.2

-21.1 ( 1.1 -37.6

-16.9

-44.8

411

-13.9

-36.2

199

-14.0

-40.2

31

-5.5

-19.0

0.8

-16.3

-43.2

350

-10.7

-31.8

8

-8.7

-29.2

1

-12.7

-37.3

17

∆S_m

K_m, M^-1

53

1000

q

∆H_3m

∆S_3m

k

20.8 ( 0.2

12.6 ( 0.7

2.1

19.2 ( 0.1

7.9 ( 0.4

2.7

21.1 ( 0.2

15.3 ( 0.7

4.6

20.5 ( 0.4

10.6 ( 1.4

1.2

q

_3m, s^-1

<2 × 10^-2

<10^-3

f

a

b

d

TTP ) P{(2,4,6-OMe)₃C₆H₂}₃. Reference 1. ^cReferences 11 and 12. All ∆H values in kcal mol^{-1 e}All ∆S values in cal mol^-1K^-1

. .

^fEstimated from product distribution.

Sch em e 6

rangements in the five-coordinate d⁶ruthenium com-

plexes Ru(PPh₃)₃Cl₂and Ru(PPh₃)₃(H)(Cl) have been

reported to be 10.0 ( 0.4 and 13.4 ( 0.6 kcal mol^-1

,

respectively.¹⁹

Finally, if PMe₃is present in excess, 8a reacts

analogously to 7a to give the half-sandwich complex

[Ru(η⁵-C₅H₄OH)(PMe₃)₂(tu)]CF₃SO₃(15) together with

free C₅H₄PMe₃(16a ) in quantitative yield as monitored

by ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopies (Scheme

2).

Cyclopentadienone is able to act, in addition to its

simple diene function, both as a 2e^-oxidizing agent and

as a one-proton acceptor while remaining coordinated.

In this way it promotes the formation of substituted

hydroxyruthenocenes in the final reaction step, i.e., the

formation of complexes 12 and 13. With respect to C₅H₅

ring activation, however, its role is less clear, and

therefore, we prepared the cationic 1,3-butadiene com-

plex [Ru(η⁵-C₅H₅)(η⁴-C₄H₆)(CH₃CN)]CF₃SO₃(17) for

comparison with the analogous cyclopentadienone com-

plex 2. Complex 17 has been prepared by the reaction

of [Ru(η⁵-C₅H₅)(CH₃CN)₃]CF₃SO₃with 1,3-butadiene in

moderate yield. Treatment of 17 with PMe₃(>2 equiv)

in acetone at room temperature gives the η³-allyl

intermediate, which is not observed in the ¹H NMR

spectrum, apparently undergoes a 1,4 hydrogen shift to

give the more stable η(1,2,3)-1-PMe₃-2-buten-1-yl isomer

18 (anti Me, syn PMe₃complex). In the course of this

rearrangement, PMe₃is also substituted for CH₃CN. A

structural view of 18, as determined by X-ray crystal-

lography, is shown in Figure 3 with selected bond

distances and angles given in the caption. The allyl

moiety adopts an exo conformation with respect to the

metal-coordinated PMe₃ligand. This conformation is

also maintained in solution, and no evidence for an endo/

exo equilibrium is found. Complex 18 has been charac-

terized by a combination of ¹H and ³¹P NMR spec-

troscopies and elemental analysis.

complex

[Ru(η⁵-C₅H₅)(η(1,2,3)-1-PMe₃-2-buten-1-yl)-

(PMe₃)]PF₆(18) in 95% yield (Scheme 6). ¹H NMR

monitoring indicated essentially quantitative conver-

sion. However, with equimolar amounts of each reagent,

the reaction is incomplete, but no complexes other than

17 and 18 together with free CH₃CN are observed. At

lower temperatures, no reaction at all takes place, and

there is no indication for the formation of an η³-

cyclopentadienyl complex. These observations suggest

that the C₅H₄O ligand plays an important role in the

ring slippage of C₅H₅. The formation of 18 involves

regioselective addition of PMe₃at the terminal carbon

atom, as one would expect on the basis of the Davies-

Green-Mingos rules.²Under these conditions, the ad-

dition is kinetically controlled, resulting in the sole

formation of the anti η³-allyl isomer (as drawn). How-

ever, the η(1,2,3)-4-PMe₃-2-buten-1-yl (anti CH₂PMe₃)

Mech a n istic Con sid er a tion s. A mechanistic ratio-

nale for the transformation of the η³-C₅H₅intermediates

6-8 to the various products is given in Scheme 7. The

activation of the already slipped C₅H₅ligand in 6-8

may proceed via a further η³f η¹ring slippage process

to give the coordinatively unsaturated species A. The

presence of A is inferred from ¹H NMR spectroscopy.

In an R-H elimination/H migration sequence (steps A

f B f C) the 18-electron cyclopentadienylidene com-

plex C is formed. It has to be noted that mononuclear

complexes with a terminal cyclopentadienylidene ligand

(19) For intramolecular isomerizations of five-coordinate d⁶ruthe-

nium complexes see: Hoffman, P. R.; Caulton, K. G. J . Am. Chem.

Soc. 1975, 97, 4221. McNeil, K.; Anderson, K.; Bergman, R. G. J . Am.

Chem. Soc. 1997, 119, 11244.

5680 Organometallics, Vol. 17, No. 26, 1998

Simanko et al.

Sch em e 7

complex [Ru(η⁵-C₅H₄OH)(PR₃)₂L]⁺(14, 15) together

with free C₅H₄PR₃(16) will be formed.

Kin etic Stu d ies. The reactions shown in Scheme 3

have been studied in detail by means of stopped-flow

1

spectrophotometry and H NMR spectroscopy, with the

results summarized in Tables 1 and 2. The kinetic and

NMR spectroscopic studies allow observation of two

reaction pathways: reversible nucleophilic attack of PR₃

at the metal center providing the intermediate [Ru(η³-

C₅H₅)(η⁴-C₅H₄O)(L)(PR₃)]⁺(6-8) (pathway 1) and re-

versible nucleophilic attack at the cyclopentadienone

ligand giving an η³-cyclopentenoyl complex [Ru(η⁵-

C₅H₅)(η³-C₅H₄O-PR₃)(L)]⁺(9-11) (pathway 2).

F igu r e 3. Structural view of [Ru(η⁵-C₅H₅)(η(1,2,3)-1-PMe₃-

2-buten-1-yl)(PMe₃)]PF₆(18) showing 20% thermal el-

lipsoids (only one of the two crystallographically indepen-

The majority of the new kinetic results presented here

involve attack of the nucleophile at Ru, leading to

modification of the C₅H₅ring and producing 12. The

details of the data collection and establishment of the

rate laws are presented in the Experimental Section. A

-

dent complexes shown; PF₆omitted for clarity). Selected

bond lengths (Å) and angle (deg): Ru(1)-C(1-5)_av

2.207(5), Ru(1)-C(6) 2.187(4), Ru(1)-C(7) 2.101(4), Ru(1)-

C(8) 2.220(4), Ru(1)-P(2) 2.304(1), C(6)-C(7) 1.431(5),

C(7)-C(8) 1.430(6), C(8)-C(9) 1.505(6), C(6)-P(1)

1.767(4); C(6)-C(7)-C(8) 118.0(4).

standard for comparison is the reaction of 2 with PPrⁿ

.

3

The data fit a two-term rate law involving reversible

formation of an intermediate 6 followed by irreversible

formation of the product 12. The rate constants are

identified in Scheme 3 as k_1mand k_2mfor the first step

and k_3mfor the product formation step. An example of

the data is presented in Figure 4. The data points are

the high and low pseudo-first-order rate constants

observed and the amplitude ratio, all at 25 °C. The solid

lines represent the fit to all of the data (85 observations

are as yet unknown²⁰but have been trapped by the

formation of a [2+2] cycloaddition dimer²¹and have

been postulated as intermediates in the decomposition

of titanocene.²²Subsequent migration of the coordinated

phosphine to the R-carbon atom of the carbene moiety

produces D. The latter, again a coordinatively unsatur-

ated species, can generate the 1,1′-disubstituted product

via E and release of L. This reaction is restricted to

complexes with comparatively weak Ru-L bonds, viz.

Ru-(µ)OdC₅H₄(1) and Ru-NCCH₃(2). Alternatively,

if phosphine is present in excess (>2 equiv) and attack

of a second phosphine molecule at Ru intercepts the

formation of E, due to a stronger Ru-L bond (L )

pyridine, thiourea), intermediate F and eventually, via

interaction of another PR₃molecule, the half-sandwich

at 28 different conditions of temperature and PPrⁿ

3

concentration). The rate constants at 25 °C and their

associated activation parameters for all reactions in-

volving attack at Ru are presented in Table 1. The PPrⁿ

3

reaction is typical in showing a small activation en-

thalpy (4.8 kcal mol^-1) along with a large, negative

entropy of activation (-30 cal mol^-1K^-1) for k_1m

,

characteristic of a bimolecular process. The two uni-

molecular processes, k_2mleading back to the reactants

and k_3mleading to products, both have much larger

activation enthalpies (21.7 and 19.2 kcal mol^-1, respec-

tively) and positive activation entropies (15 and 8 cal

mol^-1K^-1). The rest of the data in Table 1 were collected

similarly, or with some variation when the apparent

(20) Wadepohl, H.; Galm, W.; Pritzkow, H.; Wolf, A. Chem.sEur.

J . 1996, 2, 1453.

(21) Hermann, W. A.; Plank, J .; Ziegler, M. L.; Weidenhammer, K.

Angew. Chem., Int. Ed. Engl. 1978, 17, 777.

(22) Brintzinger, H. H.; Bercaw, J . J . Am. Chem. Soc. 1970, 92, 6182.

Activation of η⁵-Cyclopentadienyl Ligands

Organometallics, Vol. 17, No. 26, 1998 5681

Ta ble 2. Activa tion P a r a m eter a n d Ra te Con sta n t Da ta a t 25 °C for th e Rea ction s of

[Ru (η⁵-C₅H₅)(η⁴-C₅H₄O)(L)]CF ₃SO₃(L ) CH₃CN (2), P yr id in e (3), Th iou r ea (4)) w ith Ter tia r y P h osp h in es in

Aceton e To Give [Ru (η⁵-C₅H₅)(η⁵-C₅H₄OH-2-P R₃)] (13) via [Ru (η⁵-C₅H₅)(η³-C₅H₄O-2-P R₃)(L)]⁺(9, 10, or 11)

CH₃CN

pyridine

thiourea

PR₃pK_a;

cone angle,

deg^c

TTP^a

11.0; 184

PMePh₂

P(PhOMe)₃

4.59; 145

PPh₃

TTP

11.0; 184

PMe₂Ph

6.50; 122

PMePh₂

4.57; 136

TTP

11.0; 184

PMe₂Ph

6.50; 122

PMePh₂

4.57; 136

b

4.57; 136

2.73; 145

q d

∆H_1c

∆S_1c

k

8.7 ( 0.2

13.1 ( 0.1

11.6 ( 0.1

11.2 ( 0.2

14.8 ( 0.8

9.8 ( 0.5

10.3 ( 0.6

14.2 ( 0.1

15.9 ( 1.1

q e

-15.4 ( 0.7 -13.9 ( 0.5 -18.6 ( 0.2 -22.5 ( 0.5 -13.6 ( 0.7 -12.6 ( 2.5 -31.5 ( 1.6 -22.4 ( 2.0 -15.7 ( 0.3 -12.3 ( 3.5

_1c, M^-1s^-11241

1.4

1.7

0.22

38

0.17

5.0 × 10^-22.1

8.8 × 10^-22.8 × 10^-2

q

∆H_2c

∆S_2c

k

23.4 ( 0.5

9.7 ( 1.7

20.9 ( 0.4

0.9 ( 1.0

20.6 ( 0.1

5.3 ( 0.4

0.074

q

_2c, s^-1

6.1 × 10^-34.2 × 10^-3

∆H_c°

-10.3

-23.6

230

-9.3

-19.5

405

-9.0

-27.8

3.0

∆S_c°

K_c, M^-1

q

∆H_3c

∆S_3c

k

19.9 ( 0.1

8.4 ( 0.2

1.13

21.3 ( 0.2

6.1 ( 0.6

23.3 ( 0.1

13.6 ( 0.2

23.7 ( 0.2

13.9 ( 0.5

2.9 × 10^-2

24.3 ( 0.6

9.1 ( 2.1

23.5 ( 0.2

27.4 ( 0.8^b

q

f

6.6 ( 0.7

f

12.8 ( 0.5

f

_3c, s^-1

3.2 × 10^-25.0 × 10^-2

9.2 × 10^-41.0 × 10^-3

3.05 × 10^-5

^eAll ∆S values in cal mol^-1K^-1

TTP ) P{(2,4,6-OMe)₃C₆H₂}₃. Reference 1d. ^cReferences 11 and 12. All ∆H values in kcal mol^-1

.

a

b

d

^fDecomposition occurred.

Sch em e 8

F igu r e 4. Dependence of the observed rate constants and

the k_1mstep is hardly affected by both size and basicity

of the entering phosphine suggests that ring slippage

and concomitant ligand rearrangements occur to a large

extent prior to Ru-P bond formation. This may be

interpreted as a rapid preequilibrium between η⁵and

η³forms of the starting complexes 2-4, where the latter

react in a rate-determining step with the entering

phosphine to give the stable η³complexes 6-8 (Scheme

8). Thus, the unsaturated η³species [Ru(η³-C₅H₅)(η⁴-

C₅H₄O)(L)]⁺lies near in energy to the transition state

where, as depicted in Figure 5, Ru-P bond formation

is incomplete. Similar observations have been made in

ring slippage processes involving the indenyl ligand.^24,31

The k_2mpathway, on the other hand, requires the

cleavage of a strong Ru-P bond. Although there are no

absolute Ru-P bond dissociation energies available in

the literature, the activation enthalpies for PMe₃dis-

the amplitude ratio on phosphine concentration for the

reaction of 2 with PPrⁿat 25 °C. Squares represent the

3

lower rate constant, circles represent the higher rate

constant, and triangles represent the ratio of the ampli-

tudes. The solid line depicts the calculated fit to all of the

points, based on the parameters in Table 1.

rate constants for the two steps greatly diverged, as

described in the Experimental Section. A variety of

patterns can be observed in the data in Table 1. The

dependence on phosphine is demonstrated most exten-

sively for the reactions of 2. The values of k_1mand its

attendant activation parameters vary little. Considering

only k_1m(25 °C), PMe₃is somewhat more reactive than

the other phosphines, but there is little variation in the

activation parameters. When there is some variation in

the activation parameters, as with PMePh₂, they com-

pensate, leaving the k_1m(25 °C) values little different.

There is a significant increase in k_2m, due to a decrease

in ∆H^q, with decreasing pK_aof the phosphine. This trend

is most clearly seen when k_1mand k_2mare combined to

give K_m, the equilibrium constant for the formation of

the intermediate from the reactants. Excluding the

exceptionally bulky and generally differently reacting

ortho-substituted phenylphosphine P{(2,4,6-OMe)₃-

C₆H₂}₃,²³there is a decrease in stability of the inter-

mediate with decreasing basicity of the ligand. The

origin of this trend is primarily in ∆H_m°. The fact that

(24) Calhorda, M. J .; Gamelas, C. A.; Gonc¸alves, I. S.; Herdtweck,

E.; Roma˜o, C. C.; Veiros, L. F. Organometallics 1998, 17, 2597.

(25) Bryndza, H. E.; Domaille, P. J .; Paciello, R. A.; Bercaw, J . E.

Organometallics 1989, 8, 379.

(26) Gemel, C.; Kalt, D.; Sapunov, V. N.; Mereiter, K.; Schmid, R.;

Kirchner, K. Organometallics 1997, 16, 427.

(27) Breulet, J .; Lee, T. J .; Schaefer, H. F., III J . Am. Chem. Soc.

1984, 106, 6250.

(28) Hughes, R. P.; Rose, P. R.; Zheng, X.; Rheingold, A. L.

Organometallics 1995, 14, 2407

(29) (a) Margl, P.; Schwarz, K. J . Chem. Phys. 1995, 103, 683. (b)

Anh, N. T.; Elian, M.; Hoffmann, R. J . Am. Chem. Soc. 1978, 100, 110.

(c) Shen, J . K.; Thang, S. Z.; Basolo, F.; J ohnson, S. E.; Hawthorne,

M. F. Inorg. Chim. Acta 1995, 235, 89

(23) (a) Atton, J . G.; Kane-Maguire, L. A. P. J . Chem. Soc., Dalton

Trans. 1982, 1491. (b) Chapman, S.; Kane-Maguire, L. A. P. J . Chem.

Soc., Dalton Trans. 1995, 2021.

(30) Huttner, G.; Brintzinger, H. H.; Bell, L. G.; Friderich, P.;

Bejenke, V.; Neugebauer, D. J . Organomet. Chem. 1978, 145, 329.

(31) Rerek, M. E.; Basolo, F. Organometallic 1983, 2, 372.

5682 Organometallics, Vol. 17, No. 26, 1998

Simanko et al.

no sensitivity to cone angle. This is true for all three

ancillary ligands. The change from CH₃CN to pyridine

and then to thiourea produces a progressive decrease

in the rate constant due to changes in both enthalpy

and entropy of activation, with the enthalpy effect

usually dominating, but P{(2,4,6-OMe)₃C₆H₂}₃shows

more complex changes. New data on the product forma-

tion step, k_3c, also demonstrate some trends. The largest

and most basic phosphine, P{(2,4,6-OMe)₃C₆H₂}₃, leads

to the fastest reaction when CH₃CN is being expelled.

For the comparisons that can be made, in reactions with

PMe₂Ph and PMePh₂, the ancillary ligands pyridine and

thiourea slow the reaction compared to CH₃CN.

A major question to be answered is the origin of the

change in product with a change in the entering

phosphine. Only the more basic phosphines react to

produce the C₅H₅-modified 1,1′-disubstituted rutheno-

cene. The question remains as to why the more basic

phosphines do not also produce the product of attack at

C₅H₄O, the 1,2-disubstituted product. Some indication

comes from the reaction of PMePh₂, which produces both

intermediates but only the 1,2-disubstituted product.

These data were obtained by studying the reactions at

different temperatures. Considering the rate constants

at 25 °C, the reaction to form intermediate 6d , the result

of attack at Ru, is 300-fold faster than the reaction to

form intermediate 9d , in which attack has occurred at

C₅H₄O. However, the reverse reactions of these two

processes show an even greater disparity. Thus the

equilibrium constant for the formation of 6d is only 0.8

M^-1, while for the formation of 9d it is 230 M^-1. The

conversion of 6d to product could not be observed, while

9d is converted to product with a rate constant (k_3c)

similar to that of all phosphines showing this reactivity.

The trend in k_3mwith phosphine basicity, if it extrapo-

lates to PMePh₂, would give a rate constant lower than

that of the other phosphines but comparable to k_3c. Thus

the kinetics indicate that both the stability of the

intermediate and, to a lesser extent, the lower reactivity

in the product-forming step prevents the less basic

phosphines from giving the 1,1′-product. Conversely, the

enhanced stability of the intermediate formed from

phosphine attack at Ru and the enhanced reactivity in

the product-forming step for the more basic phosphines

lead to the 1,1′-disubstituted product from these nu-

cleophiles.

F igu r e 5. Reaction coordinate diagram for the conversion

of 2 to 6a .

sociation from Ru(η⁵-C₅Me₅)(PMe₃)₂X (X ) various

anionic N, S, and C donor ligands and halides) provide

approximate minimum Ru-P bond strengths which are

on the order of 23-47 kcal mol^{-1 25}

The strength of the

.

Ru-P bond in 6-8 appears to follow the order PMe₃≈

PBuⁿ> PMe₂Ph > PMePh₂> PPh₃, which parallels

3

their basicities.

The product formation step, like the initial bimolecu-

lar attack, is little affected by changes in the ligand for

the four ligands that give this rate constant. However,

the upper limit on the rate constant estimated for k_3m

from PMePh₂indicates that this process is much slower

for the least basic ligand for which attack at Ru is

observed.

The dependence of the reactivity on the ancillary

ligand L is demonstrated most completely for the

reactions of 3. The bimolecular step, k_1m, has a lower

rate constant primarily due to an increased activation

enthalpy. The values of k_2mand K_mare quite similar to

those for the reactions of 2, with the trend to decreased

stability of the intermediate with decreasing basicity

slightly more pronounced than in the first case. These

compounds do not continue to product, thus showing a

large but unmeasurable decrease in k_3m. The change of

L from pyridine to thiourea gives a further decrease in

reactivity with PMe₃(k_1m) and a similar k_2m, thus a yet

less stable intermediate. The observed effect of the

ligands L may be explained by their nucleophilicity with

respect to the [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)]⁺fragment taken

to increase in the order C₅H₄O (1) < CH₃CN (2) <

pyridine (3) < thiourea (4).¹⁵It should be noted that

none of these ancillary ligands are sterically demanding

(Figures 1 and 2). Therefore, the reactivity of 1-4

toward phosphines in the order 1 > 2 > 3 > 4 is

probably not due to significant steric contributions.

This study has also produced further kinetic data on

phosphines that attack directly at the C₄H₄O ligand,

producing 1,2-disubstituted ruthenocenes 13. The new

results and those from the first paper in this series^3d

are presented in Table 2. The addition of the bulky and

basic P{(2,4,6-OMe)₃C₆H₂}₃demonstrates a trend in the

bimolecular process, k_1c, that was not present in the

bimolecular attack at Ru, k_1m. The rate constant de-

creases as the basicity of the phosphine decreases with

In the presence of excess PR₃) PMe₃and Me₂PCH₂-

PMe₂, the η³-intermediates 7 and 8 proceed by a

different pathway to yield 14 and 15, respectively,

together with free C₅H₄PR₃(Scheme 3). The kinetics of

the reaction of 7a with PMe₃have been studied by

means of ¹H NMR spectroscopy as described in the

Experimental Section. A simple second-order rate law,

first order in each reactant, was obtained. The apparent

second-order rate constant k_4mat 25 °C is 2.4 × 10^-2

M^-1s^-1with ∆H^qof 13.8 ( 1.2 kcal mol^-1and ∆S^qof

-19.8 ( 4.5 cal mol^-1K^-1. The activation parameters

are indicative of an associative process. However, the

overall process requires two phosphines, and thus it is

unclear what process or combination of processes is

actually being observed.

As has been previously shown,¹⁵CH₃CN in 2 is

readily substituted by pyridine to give 3 quantitatively.

To establish whether this reaction proceeds via an

Activation of η⁵-Cyclopentadienyl Ligands

Organometallics, Vol. 17, No. 26, 1998 5683

Sch em e 9

associative pathway, i.e., via an η³-C₅H₅intermediate,

the kinetics of this reaction were studied by H NMR

F igu r e 6. η⁵f η³ring slippage and concomitant ligand

rearrangements of 2: CACAO drawing for the SLUMO-

LUMO inversion (in the absence of the nucleophile).

1

spectroscopy (Scheme 9). A simple second-order rate

law, first order in each reactant was obtained. The

apparent second-order rate constant at 25 °C is 1.6 ×

10^-3M^-1s^-1with a ∆H^qof 18.3 ( 0.4 kcal mol^-1and

∆S^qof -10.0 ( 1.4 cal mol^-1K^-1. These data are

consistent with a bimolecular mechanism involving

coordination of pyridine-d₅to the ruthenium center

concomitant with an η⁵to η³ring slip of the C₅H₅ligand,

followed by dissociation of the CH₃CN ligand (Scheme

7). Again the simplicity of the rate law does not allow

further information concerning the individual rate

constants to be obtained from the data.

attack at C₅H₄O does not need prior reduction in the

metal valence electron count.

Attack at the metal center requires geometric changes

toward a 16-electron intermediate in which the SLUMO

has lower energy. Otherwise, an energetically unfavor-

able 20-electron complex has to be formed. The following

proposal, shown in Figure 6, is appealing: The six-

electron donor C₅H₅can be transformed into a four-

electron donor through η⁵f η³ring slippage, thus

affording a 16-electron complex and promoting metal

attack. For the formation of [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(CH₃-

CN)(PR₃)]⁺, in addition to formation of the 16e complex

and the decrease in the SLUMO level, of primary

importance is the availability of a vacant low-lying

metal-centered orbital for the entry of PR₃. Computer

simulations of the positional changes of the ligands

C₅H₄O and CH₃CN (slipping, folding, bending) show

that the change in the orbital symmetry at the metal

center is highly unfavorable energetically. For the C₅H₅

ligand, both rotation and η⁵f η³f η¹f η³f η⁵ring-

slippage barriers are known to be very low (at least in

the absence of any ring deformations²⁹) but to be

ineffective as regards orbital symmetry changes. How-

ever, η⁵f η³slippage can provoke ring deformation

affording an allyl system that typically leads to a bent

η³-C₅H₅ligand with a dihedral angle of about 20°.³⁰

Such a rearrangement creates a vacant orbital at the

metal and may provide a low-energy associative reaction

path.³¹This is also characteristic of the indenyl sys-

tem.^24,32In the present case, the 16e complex is formed

with SLUMO-LUMO inversion. Although the new

LUMO level is lowered by C₅H₅-Ru bond weakening,

there is no orbital of suitable symmetry for nucleophilic

attack at Ru to occur unless there are a horizontal swing

of CH₃CN and concomitant rotation of the η³-C₅H₅

system to improve the conjugation in the final complex

fragment (in the absence of the nucleophile). The new

MO (the LUMO of the 16e complex) is a low-lying metal-

centered orbital suitable for attack by PR₃.

EHMO Ca lcu la tion s. An insight into a possible

mechanism of the two reaction pathways is provided by

extended Hu¨ckel molecular orbital calculations. The

LUMO and SLUMO of [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(L)]⁺

having the characteristics of the π* MO of C₅H₄O and

that of the second e_1gof C₅H₅, respectively, are relevant

to nucleophilic attack by PR₃at the C₅H₄O ligand and

at the metal. In the ground state, however, both modes

of attack are not possible without a prior change in

orbital symmetries through ligand rearrangement. Fur-

thermore, the LUMO (for attack at C₅H₄O) and the

SLUMO (for attack at the metal) lie too high in energy

and the overlap integral between these MO’s and the σ

PR₃orbital is too small. It has to be noted also that the

reactivity of [Ru(η⁵-C₅H₅)(η³-C₅H₄O-PR₃)(L)]⁺is affected

by L since its π* and/or σ orbitals participate in the

SLUMO and the LUMO, respectively. Thus, strong

π-acceptor and σ-donor ligands disfavor both modes of

nucleophilic attack in agreement with the kinetic data.

To provide better interactions between the nucleophile

and the C₅H₄O ring, the LUMO of the Ru complex must

be altered to include the p_zorbital of the C₅H₄O

R-carbons and to lower its energy. This is affected by η⁴

to η³ring slippage and subsequent gauche deformation

of the C₅H₄O ligand similar to the transition state

suggested by us previously for the nucleophilic attack

at acyclic 1,3-diene ligands.²⁶For free 1,3-butadiene, it

is noteworthy that the gauche structure is only about

0.4 kcal mol^-1higher in energy than the s-cis struc-

ture.²⁷In the case of hexafluoro-1,3-butadiene, the

gauche conformer was even shown to be the ground-

state structure.²⁸This interaction should be little af-

fected by the shape and size of PR₃but should be

sensitive to the nucleophilicity of the phosphine (see

kinetics data). It should be re-emphasized here that

Con clu sion

There is an increasing awareness of the importance

of haptotropic rearrangement reactions of polyenyl

(32) Kowaleski, R. M.; Rheingold, A. L.; Trogler, W. C.; Basolo, F.

J . Am. Chem. Soc. 1986, 108, 2460.

5684 Organometallics, Vol. 17, No. 26, 1998

Simanko et al.

Syn th eses. [Ru (η⁵-C₅H₅)(η⁴-C₅H₄O)(p y)]BAr ′₄(3′). 3 (155

mg, 0.327 mmol) and NaBAr′₄(320 mg, 0.361 mmol) were

dispersed in CH₂Cl₂(15 mL), and the mixture was stirred for

1 h at room temperature, whereupon a precipitate of NaCF₃-

SO₃formed. Solid materials were removed by filtration, and

the solution was evaporated to dryness. The pale yellow solid

was washed several times with diethyl ether to remove

unreacted NaBAr′₄and then dried under vacuum. Yield: 318

mg (82%). ¹H NMR (δ, CD₃CN, -35 °C): 8.70 (d, 2H, py), 7.59

(t, 1H, py), 7.72 (b s, 8H, Ar′), 7.65 (s, 4H, Ar′), 7.47 (t, 2H,

py), 6.15 (t, 2H), 5.44 (s, 5H, C₅H₅), 4.51 (t, 2H).

ligands which become facile processes when certain

conditions are met. In the present case, the η⁵f η³ring

slippage of the C₅H₅ligand is promoted with the aid of

the coligand cyclopentadienone, which acts as a “built-

in” oxidizing agent converting into an η⁵-bound oxo-

cyclopentadienyl ligand. This may be called the cyclo-

pentadienone effect, similar to the known indenyl effect.

The energy barrier for η⁵f η³ring slippage of the

indenyl ligand is extremely low since the fused benzo

ring regains its full aromaticity in the η³coordination

mode.

At first glance, one would surmise that the present

conversion of the 18-electron complex [Ru(η⁵-C₅H₅)(η⁴-

C₅H₄O)(L)]⁺with tertiary phosphines to give stable η³-

C₅H₅complexes of [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(L)(PR₃)]⁺is

driven by the Ru-P bond formation. However, the

kinetic analysis shows that the ring slippage reaction

is little affected by the entering nucleophile. This finding

suggests ligand rearrangements to occur prior to Ru-P

bond formation. As we have shown here, η³-C₅H₅and

possibly η¹-C₅H₅complexes are intermediates in the

formation of substituted cyclopentadienyl products; i.e.,

ring slippage is a feasible way to activate C₅H₅ligands

toward nucleophilic attack.

[Ru (η⁵-C₅H₅)(η⁴-C₅H₄O)(tu )]BAr ′₄(4′). This compound

was synthesized analogously to 3′ by treatment of 4 with

1

NaBAr′₄in CH₂Cl₂. H NMR (δ, CD₃CN, -35 °C): 7.70 (b s,

8H, Ar′), 7.64 (s, 4H, Ar′), 7.30 (b s, 2H, tu), 6.84 (b s, 2H, tu),

5.96 (b s, 2H), 5.46 (s, 5H, C₅H₅), 4.13 (b s, 2H).

NMR Sp ectr oscop ic Stu d ies. Typically, a 5 mm NMR

tube was charged with a solution of either 1, 2, 3 (3′), or 4 (4′)

(ca. 20-30 mg) in neat acetone-d₆, CD₃NO₂, or a mixture

thereof (0.5 mL) and was capped with a septum. The tube was

then cooled to an appropriate temperature, and the tertiary

phosphine (ca. 1 equiv) was added by syringe. In the case of

solid phosphines, the NMR tube was charged with complexes

1-4 and the tertiary phosphine and the sample was cooled to

an appropriate temperature. Deuterated solvent was then

added slowly by syringe. The sample was transferred to a

1

precooled NMR probe, and H and ³¹P{¹H} NMR spectra were

immediately recorded. ¹³C{¹H} NMR spectra were recorded

when the stability of the complexes allowed.

Exp er im en ta l Section

Rea ction of 1 w ith P Me₃. F or m a tion of [Ru (η³-C₅H₅)-

1

(η⁴-C₅H₄O)(P Me₃)]₂(CF ₃SO₃)₂(5a ). H NMR (δ, acetone-d₆,

Gen er a l In for m a tion . Manipulations were performed

under an inert atmosphere of nitrogen by using standard

Schlenk techniques and/or a glovebox. All chemicals were

standard reagent grade and were used without further puri-

fication. The solvents were purified according to standard

procedures.³³The deuterated solvents were purchased from

Aldrich and dried over 4 Å molecular sieves. [Ru(η⁵-C₅H₅)(η⁴-

C₅H₄O)]₂(CF₃SO₃)₂(1), [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)(CH₃CN)]CF₃-

SO₃(2), [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)(py)]CF₃SO₃(py ) pyridine)

(3), [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)(tu)]CF₃SO₃(tu ) thiourea) (4),

[Ru(η⁵-C₅H₅)(CH₃CN)₃]PF₆, and NaBAr′₄(Ar′ ) 3,5-C₆H₃(CF₃)₂)

were prepared according to the literature.^3,15,34The intermedi-

ates [Ru(η⁵-C₅H₅)(η³-C₅H₄O-PR₃)(CH₃CN]⁺(9), with the excep-

tion of [Ru(η⁵-C₅H₅)(η³-C₅H₄O-PMePh₂)(CH₃CN]⁺(9a ), were

detected only kinetically. The NMR spectra of the intermedi-

ates [Ru(η⁵-C₅H₅)(η³-C₅H₄O-PR₃)(py)]⁺(PR₃) PMe₃(10a ),

-70 ^oC): 5.68 (m, 2H), 4.76 (m, 1H), 4.66 (m, 1H), 4.60 (m,

1H), 4.43 (m, 1H), 4.32 (m, 1H), 4.08 (m, 1H), 3.84 (m, 1H),

1.83 (d, 9H, ²J _HP) 14.3 Hz). ¹³C{¹H} NMR (δ, CD₃NO₂/acetone-

d₆(1:1), -70 °C): 166.3 (CdO), 80.1, 79.6, 76.1, 75.5, 73.1,

71.4, 56.8, 56.3, 48.9 (d, J _CP) 20.8 Hz), 6.3 (d, J _CP) 50.3 Hz,

PMe₃). ³¹P{¹H} NMR (δ, acetone-d₆, -70 °C): 26.4. At tem-

peratures above -50 °C, quantitative formation of 12a was

observed.

Rea ction of 1 w ith P Cy₃. F or m a tion of [Ru (η³-C₅H₅)-

(η⁴-C₅H₄O)(P Cy₃)]₂(CF ₃SO₃)₂(5b). ¹H NMR (δ, acetone-d₆,

-78 °C): 5.79 (m, 2H), 4.80 (m, 1H), 4.65 (m, 2H), 4.52 (m,

1H), 4.46 (m, 1H), 4.28 (m, 1H), 3.99 (m, 1H), 2.63 (m, 3H),

2.00-1.20 (m, 30H). ³¹P{¹H} NMR (δ, acetone-d₆, -78 °C):

31.9. At temperatures above -50 °C, quantitative formation

of 12f was observed.

PBuⁿ(10b), PMe₂Ph (10c), PMePh₂(10d )) and [Ru(η⁵-C₅H₅)-

3

Rea ction of 1 w ith P {(2,4,6-OMe)₃C₆H₂}₃. F or m a tion of

[R u (η³-C₅H ₅)(η⁴-C₅H ₄O)(P {(2,4,6-OMe )₃C₆H ₂}₃)]₂(CF ₃-

SO₃)₂(5c). ¹H NMR (δ, acetone-d₆, -78 °C): 6.35-6.10 (m,

6H), 5.66 (m, 2H), 5.04 (m, 1H), 4.89 (m, 1H), 4.72 (m, 1H),

4.60 (m, 1H), 4.46 (m, 1H), 4.33 (m, 1H), 3.90-3.30 (m, 28H).

The resonance of one of the η³-C₅H₅protons was obscured by

those of the P{(2,4,6-OMe)₃C₆H₂}₃ligand. ³¹P{¹H} NMR (δ,

acetone-d₆, -78 °C): 6.5. At temperatures above -50 °C,

quantitative formation of [Ru(η⁵-C₅H₄P{(2,4,6-OMe)₃C₆H₂}₃)-

(η⁵-C₅H₄OH)]⁺(12g) was observed. ¹H NMR for 12g (δ,

acetone-d₆, 20 °C): 6.31 (d, 9H, J ) 4.6 Hz), 4.63 (m, 2H), 4.58

(m, 2H), 4.51 (m, 4H), 3.91 (s, 18H), 3.83 (s, 9H). ³¹P{¹H} NMR

for 12g (δ, acetone-d₆, 20 °C): 1.0.

(η³-C₅H₄O-PR₃)(tu)]⁺(PR₃) PMe₃(11a ), PBuⁿ(11b), PMe₂-

3

Ph (11c), PMePh₂(11d )) have been described previously.^3d

Syntheses and NMR spectra of [Ru(η⁵-C₅H₄PR₃)(η⁵-C₅H₄OH)]⁺

(PR₃) PMe₃(12a ), PBuⁿ₃(12b), PMe₂Ph (12c), PMePh₂(12d ),

PPh₃(12e), PCy₃(12f)) and [Ru(η⁵-C₅H₅)(η⁵-C₅H₃-2-PR₃-OH)]⁺

(PR₃) PMe₃(13a ), PBuⁿ₃(13b), PMe₂Ph (13c), PMePh₂(13d ),

PPh₃(13e), PCy₃(13f)) have been reported elsewhere.³Infra-

red spectra were recorded on a Perkin-Elmer 16PC FT IR

spectrometer. ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectra were

recorded on a Bruker AC 250 spectrometer operating at 250.13,

62.86, and 101.26 MHz, respectively, and were referenced to

SiMe₄and to H₃PO₄(85%). Temperature readings were

calibrated by using the method of Raiford et al.,³⁵corrected to

250.13 MHz, by adding a capillary of methanol to the experi-

mental sample. The assignments of the proton resonances were

aided by double-resonance experiments and ¹H-¹H shift

correlated (COSY) spectra. Microanalyses were carried out by

the Microanalytical Laboratories, University of Vienna.

Rea ction of 1 w ith P P h ₃. F or m a tion of [Ru (η³-C₅H₅)-

1

(η⁴-C₅H₄O)(P P h ₃)]₂(CF ₃SO₃)₂(5d ). H NMR (δ, acetone-d₆,

-90 °C): 5.51 (m, 1H), 5.46 (m, 1H), 5.38 (m, 1H), 4.95 (m,

1H), 4.89 (m, 1H), 4.82 (m, 1H), 4.74 (m, 1H), 4.54 (m, 1H),

4.48 (m, 1H). The resonances of the PPh₃ligand are superim-

posed by the resonances of the free PPh₃ligand. ³¹P{¹H} NMR

(δ, acetone-d₆, -90 °C): 19.5. At temperatures above -50 °C,

quantitative formation of 12e was observed.

Rea ction of 1 w ith Me₂P CH₂P Me₂. F or m a tion of [Ru -

(η³-C₅H₅)(η⁴-C₅H₄O)(η¹(P )-Me₂P CH₂P Me₂)]₂(CF ₃SO₃)₂(5e).

¹H NMR (δ, acetone-d₆, -81 °C): 5.65 (m, 2H), 4.73 (m, 1H),

4.67 (m, 1H), 4.60 (m, 1H), 4.45 (m, 1H), 4.28 (m, 1H), 4.10

(33) Perrin, D. D.; Armarego, W. L. F. Purification of Laboratory

Chemicals, 3rd ed.; Pergamon: New York, 1988.

(34) Brookhart, M.; Grant, B.; Volpe, J . Organometallics 1992, 11,

3920.

(35) Raiford, D. S.; Fisk, C. L.; Becker, E. D. Anal. Chem. 1979, 51,

1, 2050.

Activation of η⁵-Cyclopentadienyl Ligands

Organometallics, Vol. 17, No. 26, 1998 5685

(m, 1H), 3.81 (m, 1H), 1.76 (d, 6H, ²J _HP) 13.5 Hz, PMe₂), 1.34

(CdO), 129.5 (CN), 78.3, 75.8, 66.0, 52.5, 50.4 (d, J _CP) 17.8

Hz), 20.9 (d, J _CP) 47.7 Hz, PCH₂CH₂P), 17.0 (dd, J _CP) 44.5

Hz, J _CP) 15.9 Hz, PCH₂CH₂P), 13.4 (d, J _CP) 13.4 Hz, PMe₂),

5.2 (CH₃CN), 3.6 (d, J _CP) 48.3 Hz, PMe₂). ³¹P{¹H} NMR (δ,

2

(t, 2H, J _HP) 3.2 Hz, PCH₂P), 0.97 (d, 6H, J _HP) 8.4 Hz,

2

PMe₂). ³¹P{¹H} NMR (δ, acetone-d₆, -81 °C): 29.5 (d, J _PP

)

2

35.9 Hz), -43.4 (d, J _PP) 35.9 Hz).

acetone-d₆, -70 °C):. 29.1 (d, ³J _PP) 34.1 Hz), -43.7 (d, ³J _PP

)

Rea ction of 2 w ith P Me₃. F or m a tion of [Ru (η³-C₅H₅)-

(η⁴-C₅H₄O)(P Me₃)(CH₃CN)]CF₃SO₃(6a). ¹H NMR (δ, acetone-

d₆, -90 °C): 5.63 (m, 2H, H^3,4), 4.95 (m, 2H, H^7,8), 4.32 (m,

1H, H¹), 3.93 (m, 2H, H^6,9), 3.81 (m, 2H, H^2,5), 3.66 (s, 3H),

1.76 (d, 9H, ²J _HP) 14.4 Hz).¹³C{¹H} NMR (δ, acetone-d₆, -90

34.1 Hz).

Rea ction of 3 w ith P Me₃. F or m a tion of [Ru (η³-C₅H₅)-

(η⁴-C₅H₄O)(P Me₃)(p y)]CF ₃SO₃(7a ). To a solution of 3 (200

mg, 0.422 mmol) in acetone-d₆(5 mL) was added PMe₃(0.86

mL, 0.844 mmol), resulting in the immediate formation of a

pale yellow precipitate, which was collected on a glass frit,

washed with diethyl ether, and dried under vacuum. Yield:

230 mg (99%). Anal. Calcd for C₁₉H₂₃F₃NO₄RuS: C, 41.46; H,

4.21; N, 2.54; P, 5.82. Found: C, 42.41; H, 4.30; N, 2.42; P,

5.63. ¹H NMR (δ, CD₃NO₂, -20 °C): 9.17 (m, 2H, py), 7.91

(m, 1H, py), 7.44 (m, 2H, py), 5.49 (m, 2H, H^3,4), 4.83 (m, 2H,

H^7,8), 3.79 (m, 2H, H^6,9), 3.70 (m, 2H, H^2,5), 3.10 (m, 1H, H¹),

1.58 (d, 9H, ²J _HP) 14.0 Hz). ¹³C{¹H} NMR (δ, CD₃NO₂/acetone-

d₆(1:3), -20 °C): 173.7 (CdO), 160.6 (py), 139.1 (py), 127.3

°C): 173.7 (CdO), 129.4 (CN), 78.3, 75.6, 65.8, 52.4 (d, J _CP

)

5.3 Hz), 50.4 (d, J _CP) 14.8 Hz), 5.4 (d, J _CP) 54.1 Hz, PMe₃).

³¹P{¹H} NMR (δ, acetone-d₆, -90 °C): 24.6. At temperatures

above -50 °C, quantitative formation of 12a was observed.

Rea ction of 2 w ith P Bu ⁿ₃. F or m a tion of [Ru (η³-C₅H₅)-

1

(η⁴-C₅H₄O)(P Bu ⁿ₃)(CH₃CN)]CF ₃SO₃(6b). H NMR (δ, ace-

tone-d₆, -90 °C): 5.66 (m, 2H, H^3,4), 4.92 (m, 2H, H^7,8), 4.35

(s, 1H, H¹), 3.96 (m, 2H, H^6,9), 3.80 (m, 2H, H^2,5), 2.18 (m, 6H),

1.60-1.20 (m, 12H), 0.87 (t, 9H).¹³C{¹H} NMR (δ, acetone-d₆,

-90 °C): 173.8 (CdO), 129.8 (CN), 78.3, 75.9, 66.1, 53.0, 49.2

(d, J _CP) 13.9 Hz), 25.3 (d, J _CP) 15.3 Hz, PBu₃), 24.5, 17.8,

17.1, 5.4 (CH₃CN). ³¹P{¹H} NMR (δ, acetone-d₆, -90 °C): 27.5.

At temperatures above -50 °C, quantitative formation of 12b

was observed.

(py), 78.0, 76.4, 68.3, 52.6 (d, J _CP) 5.1 Hz), 51.2 (d, J _CP

)

19.9 Hz), 6.0 (d, J _CP) 49.5 Hz, PMe₃). ³¹P{¹H} NMR (δ, CD₃-

NO, -20 °C): 30.7. At room temperature, formation of 12a

and 13a was observed.

Rea ction of 2 w ith P Me₂P h . F or m a tion of [Ru (η³-

Rea ction of 3 w ith P Bu ⁿ₃. F or m a tion of [Ru (η³-C₅H₅)-

C₅H₅)(η⁴-C₅H₄O)(P Me₂P h )(CH₃CN)]CF ₃SO₃(6c). H NMR

(η⁴-C₅H₄O)(P Bu ⁿ₃)(p y)]CF ₃SO₃(7b). H NMR (δ, CD₃NO₂/

1

(δ, acetone-d₆, -70 °C): 8.00-7.60 (m, 5H), 5.19 (m, 2H, H^3,4),

acetone-d₆(1:3), -66 °C): 9.18 (m, 2H, py), 7.94 (m, 1H, py),

7.47 (m, 2H, py), 5.56 (m, 2H, H^3,4), 4.86 (m, 2H, H^7,8), 3.79

(m, 2H, H^6,9), 3.75 (m, 2H, H^2,5), 3.17 (m, 1H, H¹), 2.02 (m,

6H, PBu₃), 1.36 (m, 12H, PBu₃), 0.85 (m, 9H, PBu₃). ¹³C{¹H}

NMR (δ, CD₃NO₂/acetone-d₆(1:3), -66 °C): 173.9 (CdO), 160.5

(py), 139.3 (py), 127.4 (py), 78.1, 76.5, 68.3, 53.2, 49.3 (d, J _CP

) 12.5 Hz), 25.4 (d, J _CP) 15.3 Hz, PBu₃), 15.3 (s, PBu₃), 17.8

(d, J _CP) 42.5 Hz, PBu₃), 114.3 (s, PBu₃). ³¹P{¹H} NMR (δ,

CD₃NO₂/acetone-d₆(1:3), -66 °C): 26.7. At room temperature,

quantitative formation of 13b was observed.

Rea ction of 3 w ith P Me₂P h . F or m a tion of [Ru (η³-

C₅H₅)(η⁴-C₅H₄O)(P Me₂P h )(p y)]CF ₃SO₃(7c). ¹H NMR (δ,

acetone-d₆, -70 °C): 9.15 (m, 2H, py), 8.0-7.5 (m, 8H, py and

PMe₂Ph), 5.19 (m, 2H, H^3,4), 4.83 (m, 2H, H^7,8), 3.72 (m, 2H,

H^6,9), 3.65 (m, 2H, H^2,5), 3.57 (m, 1H, H¹), 2.08 (m, 9H, PMe₂-

Ph). ¹³C{¹H} NMR (δ, acetone-d₆, -70 °C): 174.3 (CdO), 160.8

(py), 144.4 (d, J _CP) 13.9 Hz, PMe₂Ph), 139.2 (py), 135.5 (s,

PMe₂Ph), 134.0 (d, J _CP) 9.3 Hz, PMe₂Ph), 130.8 (d, J _CP) 11.6

Hz, PMe₂Ph), 127.5 (py), 77.8, 76.5, 68.5, 53.4 (d, J _CP) 11.1

Hz), 51.9 (d, J _CP) 5.1 Hz), 5.1 (d, J _CP) 49.5 Hz, PMe₂Ph).

³¹P{¹H} NMR (δ, acetone-d₆, -70 °C): 22.0. At room temper-

ature, quantitative formation of 13c was observed.

4.80 (m, 2H, H^7,8), 4.45 (m, 1H, H¹), 3.85 (m, 2H, H^6,9), 3.71

2

(m, 2H, H^2,5), 2.60 (s, 3H), 2.21 (d, 6H, J _HP) 13.7 Hz). ³¹P-

{¹H} NMR (δ, acetone-d₆, -70 °C): 22.2. At temperatures

above -50 °C, quantitative formation of 12c was observed.

Rea ction of 2 w ith P MeP h ₂. F or m a tion of [Ru (η³-

C₅H₅)(η⁴-C₅H₄O)(P MeP h ₂)(CH₃CN)]CF ₃SO₃(6d ) a n d [Ru -

(η⁵-C₅H₅)(η³-C₅H₄O-2-P MeP h ₂)(CH₃CN)]CF ₃SO₃(9a ). The

¹H NMR spectrum was immediately recorded showing the

formation of both [Ru(η³-C₅H₅)(η⁴-C₅H₄O)(PMePh₂)(CH₃CN)]-

CF₃SO₃(6d ) and [Ru(η⁵-C₅H₅)(η³-C₅H₄O-2-PMePh₂)(CH₃CN)]-

1

CF₃SO₃(9a ). H NMR for 6d (δ, acetone-d₆, -90 °C): 8.00-

7.60 (m, 10H, PMePh₂), 5.22 (m, 2H), 5.13 (m, 1H), 4.86 (m,

2H), 3.92 (m, 2H), 3.80 (m, 2H), 2.70 (s, 3H), 2.54 (d, 3H, J _HP

1

) 13.9 Hz, PMePh₂). H NMR for 9a (δ, acetone-d₆, -90 °C):

8.00-7.60 (m, 10H), 5.49 (m, 1H), 4.70 (s, 5H), 4.11 (d, 1H,

J _HP) 10.5 Hz), 3.67 (m, 1H), 3.52 (m, 1H), 2.61 (s, 3H), 2.60

(d, 3H, J _HP) 13.9 Hz, PMePh₂). When the solution was

warmed to ambient temperature, only the resonances of 13d

and free CH₃CN were observed.

Rea ction of 2 w ith P {(2,4,6-OMe)₃C₆H₂}₃. F or m a tion of

[R u (η⁵-C₅H ₅)(η⁵-C₅H ₃OH -2-P {(2,4,6-OMe )₃C₆H ₂}₃)]CF ₃-

1

Rea ction of 3 w ith P Cy₃. F or m a tion of [Ru (η³-C₅H₅)-

(η⁴-C₅H₄O)(P Cy₃)(p y)]CF ₃SO₃(7d ). ¹H NMR (δ, acetone-d₆,

-97 °C): 9.35 (m, 2H, py), 8.05 (m, 1H, py), 7.60 (m, 2H, py),

5.68 (m, 2H), 4.96 (m, 2H), 3.92 (m, 2H), 3.78 (m, 2H), 3.12

(m, 1H, H¹), 2.55 (m, 3H, PCy₃). The other resonances of PCy₃

were obscured by those of free PCy₃. ³¹P{¹H} NMR (δ, acetone-

d₆, -97 °C): 20.0. At room temperature, quantitative forma-

tion of 13f was observed.

SO₃(13g). H NMR (δ, CD₃CN, 20 °C): 6.21 (d, 6H, J ) 4.6

Hz), 4.70 (m, 1H), 4.41 (s, 5H), 4.39 (m, 1H), 4.25 (m, 12H),

3.87 (s, 9H), 3.45 (s, 18H). ³¹P{¹H} NMR (δ, CD₃CN, 20 °C):

-3.7.

Rea ction of 2 w ith Me₂P CH₂P Me₂. F or m a tion of [Ru -

(η³-C ₅H ₅)(η⁴-C ₅H ₄O )(η¹(P )-Me ₂P C H ₂P Me ₂)(C H ₃C N )]-

1

CF ₃SO₃(6e). H NMR (δ, acetone-d₆, -70 °C): 5.59 (m, 2H,

H^3,4), 4.91 (m, 2H, H^7,8), 4.28 (s, 1H, H¹), 3.94 (m, 2H, H^6,9),

3.81 (m, 2H, H^2,5), 2.65 (s, 3H), 2.37 (d, 2H, J _HP) 14.5 Hz,

Rea ction of 3 w ith Me₂P CH₂P Me₂. F or m a tion of [Ru -

(η³-C₅H₅)(η⁴-C₅H₄O)(η¹(P )-Me₂P CH₂P Me₂)(p y)] BAr ′₄(7e).

¹H NMR (δ, acetone-d₆, -47 °C): 9.20 (m, 2H, py), 7.95 (m,

1H, py), 7.82 (m, 8H, BAr′₄), 7.73 (m, 4H, BAr′₄), 7.48 (m, 2H,

py), 5.57 (m, 2H, H^3,4), 4.91 (m, 2H, H^7,8), 3.77 (m, 2H, H^6,9),

3.72 (m, 2H, H^2,5), 3.34 (m, 1H, H¹), 2.29 (d, 2H, J _HP) 14.6

Hz, PCH₂P), 1.67 (d, 6H, J _HP) 13.6 Hz, PMe₂), 1.11 (d, 6H,

J _HP) 3.4 Hz, PMe₂). ¹³C{¹H} NMR (δ, acetone-d₆, -47 °C):

174.0 (CdO), 163.0 (BAr′₄, J _CB) 49.6 Hz), 160.6 (py), 139.0

(py), 135.9 (BAr′₄), 130.3 (BAr′₄, J _CF) 32.4 Hz), 127.2 (py),

125.7 (BAr′₄, J _CF) 272.0 Hz), 118.5 (BAr′₄), 77.5, 76.4, 68.4,

PCH₂P), 1.76 (d, 6H, J _HP) 13.7 Hz, PMe₂), 1.17 (d, 6H, J _HP

)

3.3 Hz, PMe₂). ¹³C{¹H} NMR (δ, acetone-d₆, -70 °C): 173.8

(CdO), 129.5 (CN), 78.4, 75.8, 66.0, 52.5, 51.7 (d, J _CP) 17.6

Hz), 21.2 (dd, J _CP) 44.9 Hz, J _CP) 33.3 Hz, PCH₂P), 15.8 (dd,

J _CP) 13.2 Hz, J _CP) 7.26 Hz, PMe₂), 5.2 (CH₃CN), 5.1 (dd,

J _CP) 49.9 Hz, J _CP) 5.6 Hz, PMe₂). ³¹P{¹H} NMR (δ, acetone-

2

d₆, -70 °C): 27.5 (d, J _PP) 41.3 Hz), -51.7 (d, J _PP) 41.3

Hz).

Rea ction of 2 w ith Me₂P CH₂CH₂P Me₂. F or m a tion of

[Ru (η³-C₅H₅)(η⁴-C₅H₄O)(η¹(P )-Me₂P CH₂CH₂P Me₂)(CH₃CN)]-

1

CF ₃SO₃(6f). H NMR (δ, acetone-d₆, -70 °C): 5.61 (m, 2H,

52.0, 51.8 (d, J _CP) 11.6 Hz), 21.9 (dd, J _CP) 44.6 Hz, J _CP)

H^3,4), 4.91 (m, 2H, H^7,8), 4.31 (s, 1H, H¹), 3.96 (m, 2H, H^6,9),

3.80 (m, 2H, H^2,5), 2.63 (s, 3H), 2.22 (b, 2H, PCH₂CH₂P), 1.76

(d, 6H, J _HP) 14.1 Hz, PMe₂), 1.58 (b, 2H, PCH₂CH₂P), 0.99

(s, 6H, PMe₂). ¹³C{¹H} NMR (δ, acetone-d₆, -70 °C): 173.8

32.6 Hz, PCH₂P), 16.0 (dd, J _CP) 13.2 Hz, J _CP) 7.2 Hz, PMe₂),

5.6 (dd, J _CP) 49.7 Hz, J _CP) 5.8 Hz, PMe₂). ³¹P{¹H} NMR (δ,

acetone-d₆, -47 °C): 27.5 (d, J _PP) 41.3 Hz), -52.3 (d, J _PP

41.3 Hz).

)

5686 Organometallics, Vol. 17, No. 26, 1998

Simanko et al.

3

Rea ction of 3 w ith Me₂P CH₂CH₂P Me₂. F or m a tion of

Hz, PMe₂). ³¹P{¹H} NMR (δ, CD₃NO₂, -47 °C): 27.7 (d, J _PP

3

[R u (η³-C₅H ₅)(η⁴-C₅H ₄O)(η¹(P )-Me ₂P CH ₂CH ₂P Me ₂)(p y)]

) 34.1 Hz), -46.1 (d, J _PP) 34.1 Hz).

1

[Ru (η⁵-C₅H₄OH)(P Me₃)₂(p y)]BAr ′₄(14a ). PMe₃(20 µL,

0.20 mmol) was added by syringe to a 5 mm NMR tube

containing a sample of 2 as the BAr′₄salt (40 mg, 0.034 mmol)

in acetone-d₆(0.5 mL) cooled at about -30 °C. The tube was

placed in a precooled NMR probe at -30 °C, and quantitative

BAr ′₄(7f). H NMR (δ,acetone-d₆, -47 °C): 9.20 (m, 2H, py),

7.96 (m, 1H, py), 7.81 (m, 8H, BAr′₄), 7.72 (m, 4H, BAr′₄), 7.48

(m, 2H, py), 5.59 (m, 2H, H^3,4), 4.91 (m, 2H, H^7,8), 3.81 (m, 2H,

H^6,9), 3.72 (m, 2H, H^2,5), 3.41 (m, 1H, H¹), 2.20 (m, 2H, PCH₂-

CH₂P), 1.75 (d, 6H, J _HP) 13.9 Hz, PMe₂), 1.54 (m, 2H, PCH₂-

CH₂P), 0.95 (d, 6H, J _HP) 2.4 Hz, PMe₂). ¹³C{¹H} NMR (δ,

acetone-d₆, -47 °C): 174.1 (CdO), 163.0 (BAr′₄, J _CB) 49.8

1

formation of 14a and 16a was observed within 12 h. H NMR

(δ, acetone-d₆, -30 °C): 8.72 (d, 2H, J ) 5.14 Hz, py), 7.80

(m, 9H, BAr′₄, py), 7.70 (m, 4H, BAr′₄), 7.22 (t, 2H, J ) 6.51

Hz, py), 4.14 (m, 4H, CPD), 1.54 (vt, 1H, J _HP) 3.77 Hz, PMe₃).

The OH resonance was not observed. ¹³C{¹H} NMR (δ, acetone-

d₆, -30 °C): 163.0 (BAr′₄, J _CB) 49.9 Hz), 159.1 (py), 136.9

(py), 135.8 (BAr′₄), 130.3 (BAr′₄, J _CF) 29.6 Hz), 126.1 (py),

125.7 (BAr′₄, J _CF) 271.9 Hz), 118.5 (BAr′₄), 71.5, 61.0, 21.8

(t, J _CP) 13.9 Hz, PMe₃). The CO resonance was not observed.

³¹P{¹H} NMR (δ, acetone-d₆, -30 °C): 9.1.

Hz), 160.6 (py), 139.0 (py), 135.9 (BAr′₄), 130.3 (BAr′₄, J _CF

31.6 Hz), 127.9 (py), 125.7 (BAr′₄, J _CF) 272.0 Hz), 118.5

(BAr′₄), 77.6, 76.4, 68.4, 52.0 (d, J _CP) 5.1 Hz), 50.7 (d, J _CP

)

14.8 Hz), 23.0 (dd, J _CP) 15.0 Hz, J _CP) 6.7 Hz, PCH₂CH₂P),

17.6 (dd, J _CP) 42.5 Hz, J _CP) 16.2 Hz, PCH₂CH₂P), 13.6 (d,

J _CP) 13.9 Hz, PMe₂), 4.1 (d, J _CP) 48.6 Hz, PMe₂). ³¹P{¹H}

NMR (δ, acetone-d₆, -47 °C): 27.9 (d, J _PP) 34.1 Hz), -43.9

(d, J _PP) 34.1 Hz).

Rea ction of 4 w ith P Me₃. F or m a tion of [Ru (η³-C₅H₅)-

(η⁴-C₅H₄O)(P Me₃)(tu )]CF ₃SO₃(8a ). PMe₃(7.0 µL, 0.068

mmol) was added by syringe to a 5 mm NMR tube containing

a sample of 4 (20 mg, 0.042 mmol) in CD₃NO₂(0.5 mL) cooled

at about -25 °C. The tube was placed into a precooled NMR

probe at -20 °C, and quantitative formation of 7a was

observed. Attempts to isolate this complex in pure form,

however, failed due to equilibrium reasons, and a mixture of

4 and 7a was obtained in a 2:1 ratio. ¹H NMR (δ, CD₃NO₂,

-20 °C): 8.39 (b, 4H, NH₂), 5.56 (m, 2H, H^3,4), 4.90 (m, 2H,

H^7,8), 4.52 (m, 1H, H¹), 4.01 (m, 2H, H^6,9), 3.60 (m, 2H, H^2,5),

[Ru (η⁵-C₅H₄OH)(η²(P ,P )-Me₂P CH₂P Me₂)(py)]BAr ′₄(14b).

Me₂PCH₂PMe₂(7 µL, 0.044 mmol) was added by syringe to a

5 mm NMR tube containing a sample of 2 as the BAr′₄salt

(25 mg, 0.021 mmol) in acetone-d₆(0.5 mL) cooled at about

-30 °C. The tube was kept at -30 °C for 12 h, after which it

was transferred to a precooled NMR probe at -30 °C and

quantitative formation of 14b and 16b was observed. ¹H NMR

(δ, acetone-d₆, -30 °C): 8.88 (d, 2H, J ) 5.4 Hz, py), 7.81 (m,

9H, BAr′₄, py), 7.73 (m, 4H, BAr′₄), 7.23 (t, 2H, J ) 6.6 Hz,

py), 4.17 (m, 4H), 3.66 (m, 2H, PCH₂P), 1.76 (vt, 6H, J _HP

)

4.9 Hz, PMe₂), 1.54 (vt, 6H, J _HP) 4.9 Hz, PMe₂). The OH

resonance was not observed. ³¹P{¹H} NMR (δ, acetone-d₆, -30

°C): -15.9.

2

1.65 (d, 9H, J _HP) 13.7 Hz). ¹H NMR (δ, CD₃NO₂, -20 °C):

8.40 (b, 4H, NH₂), 5.58 (m, 1H), 5.55 (m, 1H), 4.97 (m, 1H),

4.84 (m, 1H), 4.52 (m, 1H, H¹), 4.15 (m, 1H), 3.87 (m, 1H),

[R u (η⁵-C ₅H ₄O H )(η²(P ,P )-Me ₂P C H ₂C H ₂P Me ₂)(p y )]-

CF ₃SO₃(14c). Monitoring of the formation of complex 14c was

2

3.69 (m, 1H), 3.51 (m, 1H), 1.65 (d, 9H, J _HP) 13.7 Hz). ³¹P-

{¹H} NMR (δ, CD₃CN, -20 °C): 25.8. For solubility reasons,

the ¹³C{¹H} NMR (δ, CD₃CN, -20 °C) was recorded with [Ru-

(η³-C₅H₅)(η⁴-C₅H₄O)(PMe₃)(tu)]BAr′₄(8a ′): 182.8 (CdS), 171.6

(CdO), 162.3 (BAr′₄, J _CB) 49.4 Hz), 135.2 (BAr′₄), 129.3 (BAr′₄,

J _CF) 31.3 Hz), 125.0 (BAr′₄, J _CF) 271.8 Hz), 76.0, 75.7, 74.3,

73.2, 67.5, 64.8, 52.8 (d, J _CP) 20.3 Hz), 50.3 (d, J _CP) 13.0

Hz), 47.0 (d, J _CP) 4.6 Hz), 5.7 (d, J _CP) 49.9 Hz, PMe₃). At

room temperature, formation of 12a and 13a was observed.

Rea ction of 4 w ith P Bu ⁿ₃. F or m a tion of [Ru (η³-C₅H₅)-

(η⁴-C₅H₄O)(P Bu ⁿ₃)(tu )]CF ₃SO₃(8b). ¹H NMR (δ, CD₃NO₂/

acetone-d₆(1:1), -42 °C): 8.48 (b, 4H, NH₂), 5.58 (m, 1H, H^3,4),

5.53 (m, 1H, H^3,4), 4.92 (m, 1H), 4.81 (m, 1H), 4.73 (m, 1H,

H¹), 4.13 (b, 1H), 3.81 (m, 1H), 3.67 (m, 1H), 3.51 (m, 1H).

Resonances of the coordinated phosphine were obscured by

1

carried out analogously to that for 14b. H NMR (δ, acetone-

d₆, -30 °C): 8.69 (m, 1H, py), 8.57 (m, 1H, py), 7.75 (m, 1H,

py), 7.39 (m, 1H, py), 7.18 (m, 1H, py), 4.41 (m, 2H), 3.92 (m,

2H), 1.70 (m, 6H, PMe₂), 1.44 (m, 3H, PMe) 1.35 (vt, 3H, J _HP

) 3.5 Hz, PMe). The OH resonance was not observed, and the

resonances of the PCH₂CH₂P moiety were obscured by the

resonances of 16c. ³¹P{¹H} NMR (δ, acetone-d₆, -30 °C):

-15.9.

[Ru (η⁵-C₅H₄OH)(P Me₃)₂(SdC(NH₂)₂)]CF ₃SO₃(15). Moni-

toring of the formation of complex 15 was carried out analo-

gously to that for 14b. ¹H NMR (δ, CD₃NO₂, -20 °C): 4.26 (s,

2H), 4.19 (s, 2H), 1.46 (vt, 18H, J _HP) 4.2 Hz). The resonance

of the OH proton could not be detected. ¹³C{¹H} NMR (δ, CD₃-

NO₂, -20 °C): 185.8 (CdS), 126.4 (CO), 72.8, 61.3, 22.1 (t,

J _CP) 14.8 Hz, PMe₃). ³¹P{¹H} NMR (δ, CD₃NO₂, -20 °C): 8.0.

C₅H₄P Me₃(16a ). ¹H NMR (δ, acetone-d₆, -30 °C): 6.06 (m,

2H), 5.93 (m, 2H), 1.81 (d, 9H, J _HP) 13.7 Hz, Me). ¹³C{¹H}

NMR (δ, acetone-d₆, -30 °C): 113.1 (d, J _CP) 18.0 Hz), 112.2

(d, J _CP) 16.7 Hz), 13.6 (d, J _CP) 59.7 Hz, PMe₃). The resonance

of the quaternary carbon could not be detected. ³¹P{¹H} NMR

(δ, acetone-d₆, -30 °C): 4.0 (cf. ref 14).

those of free PBuⁿ

.

³¹P{¹H} NMR (δ, CD₃NO₂/acetone-d₆(1:

3

1), -42 °C): 27.2. At room temperature, quantitative formation

of 13b was observed.

Rea ction of 4 w ith P Me₂P h . F or m a tion of [Ru (η³-

C₅H₅)(η⁴-C₅H₄O)(P Me₂P h )(tu )]CF ₃SO₃(8c). ¹H NMR (δ,

CD₃NO₂, -12 °C): 8.27 (b, 4H, NH₂), 7.65-7.90 (m, 5H), 5.35

2

(m, 2H, H^3,4), 4.82 (m, 2H), 4.72 (d, 2H, J _HP) 4.1 Hz), 3.90

2

(b, 2H), 3.54 (m, 2H), 2.02 (d, 6H, J _HP) 13.5 Hz). ³¹P{¹H}

C₅H₄P Me₂CH₂P Me₂(16b). ¹H NMR (δ, acetone-d₆, -30

°C): 6.07 (m, 2H), 5.94 (m, 2H), 1.92 (d, 6H, J _HP) 13.6 Hz,

PMe₂), 0.74 (d, 6H, J _HP) 3.1 Hz, PMe₂). The resonances of

the PCH₂P moiety were obscured by those of 14b. ³¹P{¹H}

NMR (δ, acetone-d₆, -30 °C): 31.2 (d, J _PP) 50.3 Hz), 6.2 (d,

J _PP) 52.1 Hz).

NMR (δ, CD₃NO₂, -41 °C): 20.4. At room temperature,

quantitative formation of 13c was observed.

Rea ction of 4 w ith Me₂P CH₂P Me₂. F or m a tion of [Ru -

(η³-C₅H₅)(η⁴-C₅H₄O)(η¹(P )-Me₂P CH₂P Me₂)(tu )]CF₃SO₃(8d).

¹H NMR (δ, CD₃NO₂, -41 °C): 8.43 (b, 4H, NH₂), 5.54 (m,

2H, H^3,4), 4.96 (m, 1H), 4.84 (m, 1H), 4.61 (m, 1H, H¹), 4.04 (b,

1H), 3.87 (m, 1H), 3.69 (m, 1H), 3.51 (m, 1H), 2.11 (d, 2H, ²J _HP

[Ru (η⁵-C₅H₅)(η⁴-C₄H₆)(CH₃CN)]P F ₆(17). A solution of

[Ru(η⁵-C₅H₅)(CH₃CN)₃]PF₆(2.98 g, 6.86 mmol) in acetonitrile

(300 mL) was saturated with 1,3-butadiene, and the mixture

was heated at reflux for 35 min. During that time, the solution

was purged several times with 1,3-butadiene. On removal of

the solvent, a bright yellow solid was obtained, which was

collected on a glass frit, washed with diethyl ether, and dried

under vacuum. Yield: 1.26 g (45%). Anal. Calcd for C₁₁H₁₄F₆-

NPRu: C, 32.52; H, 3.47; N, 3.45. Found: C, 32.41; H, 3.30;

2

) 13.5 Hz, PCH₂P), 1.69 (d, 6H, J _HP) 13.4 Hz, PMe₂), 1.40

(s, 6H, PMe₂). ³¹P{¹H} NMR (δ, CD₃NO₂, -41 °C): 26.5 (d,

2

²J _PP) 44.9 Hz), -54.8 (d, J _PP) 44.9 Hz).

Rea ction of 4 w ith Me₂P CH₂CH₂P Me₂. F or m a tion of

[R u (η³-C₅H ₅)(η⁴-C₅H ₄O)(η¹(P )-Me₂P CH ₂CH ₂P Me₂)(t u )]-

CF ₃SO₃(8e). ¹H NMR (δ, CD₃NO₂, -47 °C): 8.37 (b, 4H, NH₂),

5.59 (m, 1H, H^3,4), 5.55 (m, 1H, H^3,4), 4.97 (m, 1H), 4.85 (m,

1H), 4.62 (m, 1H, H¹), 4.05 (b, 1H), 3.87 (m, 1H), 3.70 (m, 1H),

3.52 (m, 1H), 2.08 (b, 2H, PCH₂CH₂P), 1.66 (d, 6H, ²J _HP) 13.3

1

N, 3.50. H NMR (δ, acetone-d₆, -30 °C): 5.88 (m, 2H), 5.41

(s, 5H), 4.13 (d, 2H, J ) 7.5 Hz), 2.64 (s, 3H), 1.52 (d, 2H, J )

2

Hz, PMe₂), 1.54 (b, 2H, PCH₂CH₂P), 0.99 (d, 6H, J _HP) 2.2

9.8 Hz).

Activation of η⁵-Cyclopentadienyl Ligands

Organometallics, Vol. 17, No. 26, 1998 5687

Ta ble 3. Cr ysta llogr a p h ic Da ta

3

4‚CH₃CN

18

formula

fw

C

₁₆H₁₄F₃NO₄RuS

C₁₄H₁₆F₃N₃O₄RuS₂

512.49

C₁₅H₂₉F₆P₃Ru

517.36

474.41

cryst size, mm

space group

a, Å

b, Å

c, Å

0.11 × 0.25 × 0.70

P1h (No. 2)

7.919(1)

10.477(2)

10.856(2)

91.90(1)

106.09(1)

97.71(1)

855.2(3)

472

0.26 × 0.20 × 0.10

P1h (No. 2)

7.835 (3)

11.387 (4)

11.447(4)

83.99(1)

78.70(1)

76.91(1)

973.5(6)

512

0.50 × 0.26 × 0.25

P2₁/n (No. 14)

22.134(4)

8.623(2)

22.404(5)

R, deg

â, deg

γ, deg

V, Å³

F(000)

Z

95.31(1)

4258(2)

2096

8

1.614

298

2

F

_calc, g cm^-3

T, K

1.842

297

1.092

none

1.748

299

1.072

empirical

0.71/0.93

30

-11 e h e 11

-16 e k e 16

-16 e l e 16

15 431

µ, mm^-1(Mo KR)

abs corr

1.009

empirical

0.69/0.83

25

-31 e h e 31

-12 e k e 12

-31 e l e 31

43 536

7453

transm factor: min/max

θ

_max, deg

index ranges

25

0 e h e 9

-12 e k e 12

-12 e l e 12

3044

2848

no. of rflns measd

no. of unique rflns

no. of rflns, F > 4σ(F)

no. of params

5625

4359

251

6607

453

242

no. of restraints

0

2

0

R(F > 4σ(F)^a

0.029

0.032

0.074

-0.37/0.64

0.031

0.049

0.075

-0.39/0.52

0.039

0.045

0.102

-1.074 /1.069

R(all data)^a

R_w(all data)^b

diff Fourier peaks, min/max e Å^-3

a

b

2

R ) ∑||F_o| - |F_c||/∑|F_o|. R_w) [∑(w(F_o- F_c²)²)/∑(w(F_o²)²)]^1/2

[R u (η⁵-C₅H ₅)(η(1,2,3)-1-P Me₃-2-b u t en -1-yl)(P Me₃)]P F ₆

(18). A solution of 17 (100 mg, 0.246 mmol) in acetone (5 mL)

was treated with PMe₃(75 µL, 0.738 mmol), and the mixture

was stirred for 2 h at room temperature. Upon addition of

diethyl ether, a pale yellow precipitate was formed, which was

collected on a glass frit, washed with diethyl ether, and dried

under vacuum. Yield: 113 mg (95%). Anal. Calcd for C₁₅H₂₉F₆P₃-

Most reactions of [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)(L)]CF₃SO₃where

L ) CH₃CN showed two exponentials and were fit to a rate

law for the reversible formation of an intermediate followed

by the irreversible formation of the product, as described

previously.^3dThis leads to fit parameters (see Scheme 3) for

k

_1m, k_2m, and k_3m(pathway 1) and k_1c, k_2c, and k_3c(pathway 2).

For PPhMe₂, a third exponential that was slower and of lower

amplitude, and which showed no concentration dependence,

was observed. This process was also observed when CH₃CN

instead of acetone was the solvent, but its activation param-

eters were much different. In this case, the two faster processes

were treated as for the previously discussed phosphines. For

PPh₂Me, the steps were separated further in time so that the

reversible first step was studied independently from the

product-forming step. In such cases, the concentration depen-

dence is of the form k_obs) k₁[phosphine] + k₂and the rate

constants are identified with the slope and intercept of the

plot of k_obsvs [phosphine] as obtained by weighted linear least-

squares regression.³⁶In the single case of P{(2,4,6-OMe)₃C₆H₂}₃,

two exponentials were observed and the data were fit to the

fast preequilibrium formation of one dead end species (identi-

fied as the intermediate produced by attack at the metal) and

the irreversible formation of a second intermediate (identified

as the intermediate produced by attack at C₅H₄O) and then

further irreversible formation of the 1,2-disubstituted product.

The parameters produced from this treatment are identified

as K_m, k_1c, and k_3c. The assignment of the kinetic processes to

mechanistic steps relied on the NMR results and the signs of

the amplitudes of the optical changes.

1

Ru: C, 34.82; H, 5.65. Found: C, 34.81; H, 5.70. H NMR (δ,

acetone-d₆, 20 °C): 4.81 (s, 5H), 4.47 (m, 1H, H², J _HP) 10.6

Hz, J ¹²) 8.8 Hz, J ²³) 7.3 Hz, J ) 1.8 Hz), 3.51 (m, 1H, H³,

J ²³) 7.3 Hz, J ³⁴) 6.6 Hz, J ) 2.4 Hz), 1.97 (d, 9H, J _HP

13.7 Hz), 1.49 (d, 9H, J _HP) 8.3 Hz), 1.21 (m, 1H, H¹, J _HP

)

12.5 Hz, J _HP) 12.5 Hz, J ¹²) 8.8 Hz, J ) 1.3 Hz), 1.04 (dd,

3H, J ³⁴) 6.6 Hz, J ) 3.1 Hz). ³¹P{¹H} NMR (δ, acetone-d₆, 20

°C): 30.3, 4.7, -142.7 (s t, PF₆^-, J _PF) 707.3 Hz).

Kin etics. The stopped-flow kinetic data were obtained with

Hi-Tech SF-40 and Hi-Tech SF-61 instruments. The optical

signals at 400 nm (in the case of PPhMe₂) and at 355 nm (in

the case of P{(2,4,6-OMe)₃C₆H₂}₃) were monitored. The data

were collected as sets of 2.048 and 512 points, respectively,

corresponding to 3-4 half-lives.The data were transferred to

a DOS/Windows-based personal computer for data analysis.

The data all involved pseudo-first-order conditions with the

phosphine in large excess over the ruthenium complex. They

were fit to one exponential or a sum of two exponentials (in

one case, a third exponential was required) using the CURFIT

nonlinear least-squares routine of Bevington³⁶programmed

in QuickBasic or the Hi-Tech IS-2 software suite. The nonlin-

ear least-squares analysis of the dependence of the observed

rate constants (k) and amplitudes (A) on phosphine concentra-

tion and temperature was performed using the Scientist data

analysis package with the points weighted by 1/(k or A)².

Typically 36 different conditions of phosphine concentration

and temperature were utilized, with 3-8 replicate kinetic

measurements at each condition.

The reaction of [Ru(η⁵-C₅H₅)(η⁴-C₅H₄O)(L)]CF₃SO₃where L

) pyridine or thiourea and the phosphine PMe₃and the

reaction where L ) pyridine or PBuⁿshowed a single

3

exponential with a positive intercept in the concentration

dependence plot. This was attributed to reversible formation

of the intermediate formed by attack at the metal and allowed

resolution of k_1mand k_2m.. For the reactions with L ) pyridine

and PPh₂Me as well as for L ) thiourea with PPhMe₂and

PBuⁿ₃, a single exponential was observed and attributed to

(36) Bevington, P. R. Data Reduction and Error Analysis for the

Physical Sciences; McGraw-Hill: New York, 1969.

5688 Organometallics, Vol. 17, No. 26, 1998

Simanko et al.

the irreversible formation of the intermediate formed by attack

at C₅H₄O. The rate of the subsequent reaction to produce the

1,2-disubstituted product was measured by NMR methods. For

the reaction with L ) pyridine and P{(2,4,6-OMe)₃C₆H₂}₃and

for the reaction of L ) thiourea with PPh₂Me, a similar

situation was observed, but the subsequent product formation

step could not be studied due to decomposition of the inter-

mediate. The most complex case involves the reaction of PMe₂-

Ph with the Ru complex in which L ) pyridine. This reaction

shows two exponentials. One is attributed to the reversible

formation of the intermediate formed by attack at the Ru, and

the slower one is assigned to the irreversible formation of the

intermediate formed by attack at the C₅H₄O ligand. The latter

intermediate goes on to the 1,2-disubstituted product at a yet

much slower rate, as monitored by ¹H NMR spectroscopy. The

reaction of 3 with PMePh₂was also monitored by ¹H NMR

spectroscopy in the temperature range from 0 to 36 °C. The

concentration vs time curves were fit to a rate law for the

reversible formation of an intermediate followed by the ir-

reversible formation of the product.

oped by Hoffmann and Lipscomb,³⁷as modified by Mealli and

Proserpio.³⁸The atomic parameters were taken from the

CACAO program. All bond lengths and angles of the complexes

analyzed were those determined from crystallography or from

geometry optimization using a Walsh analysis with initial

values taken from known structural data.

Cr ysta llogr a p h ic Str u ctu r e Deter m in a tion s. Crystal,

data collection, and refinement parameters are given in Table

3. For 3, a Philips PW1100 four-circle diffractometer with

graphite-monochromated Mo KR radiation (λ ) 0.710 73 Å)

and a θ-2θ scan capability was used. For 4 CH₃CN and 18,

X-ray data were collected on a Siemens Smart CCD area

detector diffractometer (graphite-monochromated Mo KR ra-

diation, λ ) 0.710 73 Å, 0.3° ω-scan frames). Corrections for

Lorentz and polarization effects, for crystal decay, and, in the

case of 4 CH₃CN and 18, for absorption were applied. The

structures were solved by direct methods.³⁹All non-hydrogen

atoms were refined anisotropically. Hydrogen atoms were

inserted in idealized positions and were refined riding with

the atoms to which they were bonded. The structures were

refined against F².⁴⁰

The reaction of the η³intermediate 7a with PMe₃was

studied by means of ¹H NMR spectroscopy in acetone-d₆in

the temperature range -15 to 0 °C. The rate of disappearance

of 7a and the rate of the appearance of 14a were followed by

integration of the pyridine resonances at 9.2 ppm (7a ) and 8.7

ppm (14a ). PMe₃was in large excess (0.4-1.6 M) over the

ruthenium complex (0.04 M) to ensure pseudo-first-order

conditions. The linear dependence of the observed pseudo-first-

order rate constant on [PMe₃] indicates that the reaction is

first order in PMe₃and second order overall. There was no

evidence for an intermediate or a reversible reaction.

Ackn owledgm en t. Financial support from the Fonds

zur Fo¨rderung der wissenschaftlichen Forschung is

gratefully acknowledged (Project No. 11182).

Su p p or tin g In for m a tion Ava ila ble: Tables S1-S28,

listing the kinetic conditions and all of the measured rate

constants and amplitude ratios as well as the fit values, and

Tables S29-S43, giving atomic coordinates and U_eqvalues,

hydrogen coordinates and U_isovalues, anisotropic temperature

factors, complete bond lengths and angles, and least-squares

planes for complexes 3, 4‚CH₃CN, and 18 (47 pages). Ordering

information is given on any current masthead page.

The kinetics of the reaction of 2 with pyridine-d₅in acetone-

d₆as the solvent to give 3 (substitution of CH₃CN by pyridine)

1

were studied by H NMR spectroscopy. Pyridine-d₅was used

in large excess (0.4-1.6 M) over the ruthenium complex (0.04

M) to ensure pseudo-first-order conditions. The rate of disap-

pearance of 2, and the rate of appearance of 3 were followed

by integration of the respective C₅H₅proton resonances. The

observed rate constant k_obsdepended linearly on the concen-

tration of pyridine-d₅, and there was no evidence for an

intermediate or reversibility of the reaction. Measurements

over the temperature range 3-50 °C yielded the activation

parameters.

OM980701T

(37) (a) Hoffmann, R.; Lipscomb, W. N. J . Chem. Phys. 1962, 36,

2179. (b) Hoffmann, R.; Lipscomb, W. N. J . Chem. Phys. 1962, 36, 3489.

(c) Hoffmann, R. J . Chem. Phys. 1963, 39, 1397.

(38) Mealli, C.; Proserpio, D. M. J . Chem. Educ. 1990, 67, 399.

(39) Sheldrick, G. M. SHELXS97: Program for the Solution of

Crystal Structures, University of Go¨ttingen: Go¨ttingen, Germany,

1997.

EHMO Ca lcu la tion s. The extended Hu¨ckel molecular

orbital calculations were conducted using the program devel-

(40) Sheldrick, G. M. SHELXL97: Program for Crystal Structure

Refinement; University of Go¨ttingen: Go¨ttingen, Germany, 1997.

Article Doi

Kinetics and mechanism of nucleophilic substitutions on coordinated polyenes and polyenyls. 3.

DOI: 10.1021/om980701t

Source and publish data:

Authors:

Article abstract of DOI:10.1021/om980701t

Full text of DOI:10.1021/om980701t

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