Kinetics and Mechanism of Nucleophilic Substitutions on Coordinated Polyenes and Polyenyls. 1. Reactions of Tertiary Phosphines with [Ru(η5-C5H5)(η4-C 5H4O)(L)]CF3SO3 (L = CH3CN, Benzonitrile, Thiourea, Pyridine)

Article abstract of DOI:10.1021/ic960383v

Complexes of the type [Ru(η⁵-C₅H₅)(η⁴-C ₅H₄O)(L)]CF₃SO₃ (L = CH₃CN (1a), benzonitrile (1b), pyridine (2), thiourea (3)) react with tertiary phosphines to give either 1,1′- or 1,2-disubstituted ruthenocenes depending on the basicity of the entering phosphine and the nature of L. For 1a and 1b, only phosphines with a pK_a value above 5 substitute on the C₅H₅ ring while others substitute on the C₅H₄O ring. For compounds 2 and 3, the two rings are deactivated such that only the most basic phosphines react, and they attack only the C₅H₄O ring. In some cases of the reactions of 2 and 3, an intermediate is observed in which the monodentate ligand has migrated to the C₅H₅ ring while the entering nucleophile coordinates to the metal center. The mechanism by which phosphines attack a coordinated C₅H₄O ring has been established, and detailed kinetic parameters have been obtained. For the reaction of 1a with PPh₃, PPh₂Me, and P(p-PhOMe)₃ in acetone, the kinetics give a rate law indicating the reversible formation of an intermediate which goes irreversibly to the 1,2-disubstituted ruthenocene product. All three rate constants and their thermal activation parameters have been obtained for each of these reactions. For the P(p-PhOMe)₃ reaction, the volume of activation for each step has also been determined. The reaction of 2 and 3 with PBuⁿ₃, PCy₃, PPhMe₂, and PMe₃ in CD₃CN give a long-lived intermediate which also goes to the 1,2-disubstituted ruthenocene product. For the intermediates formed from 3, the kinetics of this last step have been studied to determine the rate constants and their thermal activation parameters. In the case of PBuⁿ₃, the intermediate formed from 3 has been isolated and an X-ray structure determined, establishing that phosphine attack has occurred at the C₅H₄O ring.

Full text of DOI:10.1021/ic960383v

Inorg. Chem. 1996, 35, 5923-5930
5923
Kinetics and Mechanism of Nucleophilic Substitutions on Coordinated Polyenes and
Polyenyls. 1. Reactions of Tertiary Phosphines with [Ru(η5-C5H5)(η4-C5H4O)(L)]CF3SO3
(L ) CH3CN, Benzonitrile, Thiourea, Pyridine)
Walter Simanko,1a Thomas Vallant,1a Kurt Mereiter,1b Roland Schmid,1a and
Karl Kirchner*,1a
Institute of Inorganic Chemistry and Institute of Mineralogy, Crystallography, and Structural Chemistry,
Technical University of Vienna, Getreidemarkt 9, A-1060 Vienna, Austria
John Coddington2 and Scot Wherland*,2
Department of Chemistry, Washington State University, Pullman, Washington 99164-4630
ReceiVed April 9, 1996X
Complexes of the type [Ru(η5-C5H5)(η4-C5H4O)(L)]CF3SO3 (L ) CH3CN (1a), benzonitrile (1b), pyridine (2),
thiourea (3)) react with tertiary phosphines to give either 1,1′- or 1,2-disubstituted ruthenocenes depending on the
basicity of the entering phosphine and the nature of L. For 1a and 1b, only phosphines with a pKa value above
5 substitute on the C5H5 ring while others substitute on the C5H4O ring. For compounds 2 and 3, the two rings
are deactivated such that only the most basic phosphines react, and they attack only the C5H4O ring. In some
cases of the reactions of 2 and 3, an intermediate is observed in which the monodentate ligand has migrated to
the C5H5 ring while the entering nucleophile coordinates to the metal center. The mechanism by which phosphines
attack a coordinated C5H4O ring has been established, and detailed kinetic parameters have been obtained. For
the reaction of 1a with PPh3, PPh2Me, and P(p-PhOMe)3 in acetone, the kinetics give a rate law indicating the
reversible formation of an intermediate which goes irreversibly to the 1,2-disubstituted ruthenocene product. All
three rate constants and their thermal activation parameters have been obtained for each of these reactions. For
the P(p-PhOMe)3 reaction, the volume of activation for each step has also been determined. The reaction of 2
and 3 with PBun , PCy3, PPhMe2, and PMe3 in CD3CN give a long-lived intermediate which also goes to the
3
1,2-disubstituted ruthenocene product. For the intermediates formed from 3, the kinetics of this last step have
been studied to determine the rate constants and their thermal activation parameters. In the case of PBun , the
3
intermediate formed from 3 has been isolated and an X-ray structure determined, establishing that phosphine
attack has occurred at the C5H4O ring.
Introduction
C5H4O)]22+, 1,2-disubstituted products such as [Ru(η5-C5H4-
PMe3)(η5-C5H5OH)]+ (7).3 Whether the product of nucleophilic
attack is a 1,1′- or a 1,2-disubstituted ruthenocene is controlled
by the entering phosphine and the ligand L, as depicted in
Scheme 1.
Organometallic ruthenium complexes containing the rarely
used coligand cyclopentadienone (C5H4O) have recently at-
tracted much of our attention.3,4 In complexes of the type [Ru-
(η5-C5H5)(η4-C5H4O)(L)]+, C5H4O is subject to nucleophilic
attack by tertiary phosphines at a terminus of the coordinated
1,3-diene moiety to give, when L ) CH3CN, 1,1′-disubstituted
complexes such as [Ru(η5-C5H5)(η5-C5H4OH-2-PR3)]+.3-5 Most
noteworthy, in addition to this simple diene reactivity, C5H4O
is able to accept 2e- and a proton while remaining coordinated
as hydroxocyclopentadienide. This special feature of C5H4O
A preliminary explanation for these unusual reactivity patterns
has been given in terms of a strong resonance interaction of
the C5H4O ligand with the ruthenium center.3c This explanation,
however, considers only ground state stabilization. On a more
rigorous basis, the electronic stabilization of the activated
complex must be taken into account and in particular the change
in electronic structure during the process of activation. For this
purpose kinetic investigations are necessary in order to gain
further insight into what appear to be elementary steps of
organometallic reactions. Herein we report on the kinetics and
mechanism of nucleophilic addition and substitution reactions
of tertiary phosphines to [Ru(η5-C5H5)(η4-C5H4O)(L)]CF3SO3
complexes, where L ) CH3CN, benzonitrile, pyridine, and
thiourea. In particular, we have now obtained kinetic data for
the reactions that lead to 1,2-disubstituted products as well as
a crystal structure of the intermediate in one such case.
-
effectively results in C-H activation of C5H5 and leads to
nucleophilic attack by tertiary phosphines to give, from [Ru-
(η5-C5H5)(η4-C5H4O)(CH3CN)]+ (1a) or [Ru(η5-C5H5)(η4-
X Abstract published in AdVance ACS Abstracts, September 1, 1996.
(1) (a) Institute of Inorganic Chemistry. (b) Institute of Mineralogy,
Crystallography, and Structural Chemistry.
(2) Department of Chemistry, Washington State University.
(3) (a) Kirchner, K.; Taube, H. J. Am. Chem. Soc. 1991, 113, 7039. (b)
Kirchner, K.; Taube, H.; Scott, B.; Willett, R. D. Inorg. Chem. 1993,
32, 1430. (c) Kirchner, K.; Mereiter, K.; Schmid, R.; Taube, H. Inorg.
Chem. 1993, 32, 5553. (d) Kirchner, K.; Mereiter, K.; Mauthner, K.;
Schmid, R. Inorg. Chim. Acta 1994, 217, 203. (e) Mauthner, K.;
Mereiter, K.; Schmid, R.; Kirchner, K. Organometallics 1994, 13,
5054.
Experimental Section
General Information. 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 used without
(4) Mauthner, K.; Slugovc, C.; Mereiter, K.; Schmid, R.; Kirchner, K.
Organometallics 1996, 15, 181.
(5) Liebeskind, L. S.; Bombrun, A. J. Am. Chem. Soc. 1991, 113, 8736.
S0020-1669(96)00383-7 CCC: $12.00 © 1996 American Chemical Society

5924 Inorganic Chemistry, Vol. 35, No. 20, 1996
Simanko et al.
Synthesis of [Ru(η5-C5H5)(η5-C5H3OH-2-PBun )]CF3SO3 (6a). To
Scheme 1
3
a solution of 2 (300 mg, 0.633 mmol) in CH3NO2 (5 mL), PBun3 (234
µL, 0.945 mmol) was added, and the mixture was stirred for 30 min at
35 °C. The solution was evaporated to dryness, and in order to remove
unreacted PBun , the solid residue was washed 3 times with diethyl
3
ether (10 mL). The crude product was redissolved in CH3NO2, and
undissolved materials were removed by filtration. On 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: 324 mg (85.7%). Anal. Calcd for C23H36F3O4PRuS: C, 46.22;
H, 6.07; S, 5.36. Found: C, 46.33; H, 6.16; S, 5.92. 1H NMR (δ,
CD3CN, 20 °C): 4.93 (m, 1H), 4.70 (s, 5H, C5H5), 4.60 (m, 1H), 4.48
(m, 1H), 2.32-2.17 (m, 6H), 1.62-1.41 (m, 12H), 0.94 (t, 9H).
31P{1H} NMR (δ Vs PPh3, CD3CN, 20 °C): 36.1.
Synthesis of [Ru(η5-C5H5)(η5-C5H3OH-2-PCy3)]CF3SO3 (6b).
This compound was synthesized analogously to 6a by treatment of 2
(280 mg) with 1 equiv of PCy3. Yield: 329 mg (82.3%). Anal. Calcd
for C29H42F3O4PRuS: C, 51.55; H, 6.62; S, 4.64. Found: C, 51.41;
H, 6.57; S, 4.70. 1H NMR (δ, CD3CN, 20 °C): 5.01 (m, 1H), 4.64 (s,
5H, C5H5), 4.63 (m, 1H), 4.50 (m, 1H), 2.65 (q, 3H), 2.18-1.03 (m,
30H). 31P{1H} NMR (δ Vs PPh3, CD3CN, 20 °C): 30.3.
Synthesis of [Ru(η5-C5H5)(η5-C5H3OH-2-PPhMe2)]CF3SO3 (6c).
This compound was synthesized analogously to 6a by treatment of 2
(300 mg) with 1 equiv of PPhMe2. Yield: 276 mg (79.7%). Anal.
Calcd for C19H20F3O4PRuS: C, 42.78; H, 3.78; S, 6.01. Found: C,
42.61; H, 3.80; S, 6.22. 1H NMR (δ, CD3CN, 20 °C): 7.82-7.78 (m,
5H), 4.86 (m, 1H), 4.62 (s, 5H, C5H5), 4.58 (m, 1H), 4.46 (m, 1H),
2.42 (d, 6H, J ) 14.1 Hz). 31P{1H} NMR (δ Vs PPh3, CD3CN, 20
°C): 32.7.
Reaction of 2 with PMe3 in CH3NO2. Following the protocol for
complexes 6a-c, treatment of 2 (320 mg, 0.675 mmol) with PMe3
(1.5 equiv) in CH3NO2 resulted in a 40/60 mixture of [Ru(η5-C5H5)(η5-
C5H3OH-2-PMe3)]CF3SO3 (6d) and [Ru(η5-C5H4-PMe3)(η5-C5H4OH)]-
CF3SO3 (7). No attempts have been made to separate these complexes.
Overall yield: 255 mg. NMR for 6d: 1H (δ, CD3CN, 20 °C) 5.00 (m,
1H), 4.75 (m, 1H), 4.74 (s, 5H, C5H5), 4.62 (m, 1H), 1.98 (d, 9H, 2JHP
) 14.4 Hz); 31P{1H} (δ Vs PPh3, CD3CN, 20 °C) 26.2. 7: 1H NMR
(δ, CD3CN, 20 °C): 5.19 (m, 2H), 4.96 (m, 2H), 4.83 (m, 2H), 4.39
further purification. The solvents were purified according to standard
procedures.6 The deuterated solvents were purchased from Aldrich and
dried over 4 Å molecular sieves. [Ru(η5-C5H5)(η4-C5H4O)(CH3CN)]-
CF3SO3 (1a),3a [Ru(η5-C5H5)(η4-C5H4O)(bn)]CF3SO3 (bn ) benzoni-
trile) (1b),3b [Ru(η5-C5H5)(η4-C5H4O)(py)]CF3SO3 (py ) pyridine) (2),3b
and [Ru(η5-C5H5)(η4-C5H4O)(tu)]CF3SO3 (tu ) thiourea) (3)3b were
prepared according to the literature. Infrared spectra were recorded
on a Perkin-Elmer 16PC FTIR spectrometer. 1H and 31P{1H} NMR
spectra were recorded on a Bruker AC 250 spectrometer operating at
250.13 and 101.26 MHz, respectively, and were referenced to residual
solvent protons and to PPh3. Microanalyses were carried out by the
Microanalytical Laboratories, University of Vienna.
Reaction of 1a with PPh3 in CD3NO2. A 5 mm NMR tube was
charged with 1a (30 mg, 0.069 mmol) and capped with a septum. A
solution of PPh3 (1.5 equiv) in CD3NO2 (0.5 mL) was added by syringe,
and the sample was transferred to an NMR probe. A 1H NMR spectrum
was immediately recorded. Characteristic resonances were observed
at 2.58, 2.61, and 1.99 ppm assigned to coordinated CH3CN of 1a,
coordinated CH3CN of an intermediate, and liberated CH3CN, respec-
tively. After about 60 s, only resonances of free CH3CN and [Ru(η5-
C5H5)(η5-C5H4OH-2-PPh3)]CF3SO3 (4a) were observed. In an analo-
gous fashion, a 31P{1H} NMR spectrum was recorded showing, in
addition to the signals of free PPh3, resonances at 30.2 and 27.7 ppm
indicating the formation of an intermediate and 4a, respectively.
2
(m, 2H), 2.03 (d, 9H, JHP ) 14.7 Hz).
Reaction of 2 with PMe3 in Acetone. Formation of [Ru(η5-
C5H4O)((1-4-η)-5-endo-py-C5H5)(PMe3)]CF3SO3 (8a). To a solution
of 2 (200 mg, 0.422 mmol) in acetone (5 mL), PMe3 (0.86 mL, 0.844
mmol) was added 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 C19H23F3NO4PRuS: 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),
4.83 (m, 2H), 3.79 (m, 2H), 3.70 (m, 2H), 3.10 (m, 1H), 1.58 (d, 9H,
2JHP ) 14.0 Hz). 31P{1H} NMR (δ Vs PPh3, CD3CN, 20 °C): 25.1. IR
(KBr, cm-1): 3100 (w), 2924 (s), 2830 (m, νC-H(exo)), 1593 (s, νC-O),
1480 (m), 1275 (s, CF3SO3), 1231 (CF3SO3), 1173 (s), 1048 (CF3SO3),
983 (m), 648 (CF3SO3).
Reaction of 2 with Tertiary Phosphines in Acetone-d6. Typically
a 5 mm NMR tube was charged with 2 (30 mg, 0.063 mmol) and capped
with a septum. A solution of the tertiary phosphine (ca. 1.5 equiv) in
acetone-d6 (0.5 mL) was added by syringe, and the sample was
transferred to an NMR probe. 1H NMR spectra were immediately
recorded. For PBun , the formation of intermediates [Ru(η5-C5H4O)-
Reaction of 1b with PPh3 in Acetone-d6. A 5 mm NMR tube was
charged with 1b (30 mg, 0.060 mmol) and capped with a septum. A
solution of PPh3 in acetone-d6 (0.5 mL) was added by syringe, and the
3
((1-4-η)-5-endo-py-C5H5)(PBun )]CF3SO3 (8b) and [Ru(η5-C5H5)(η3-
3
C5H4O-2-PBun )(py)]CF3SO3 (9a) was observed. NMR for 8b: 1H (δ,
3
1
sample was transferred to an NMR probe. A H NMR spectrum was
acetone-d6, 20 °C) 9.13 (m, 2H, py), 7.90 (m, 1H, py), 7.40 (m, 2H,
py), 5.61 (m, 2H), 4.86 (m, 2H), 3.88 (m, 2H), 3.85 (m, 2H), 3.16 (m,
1H). The resonances of PBun3 were superimposed by those of the free
phosphine. 1H NMR for 9a (δ, acetone-d6, 20 °C): 9.19 (m, 1H, py),
8.33 (m, 1H, py), 7.93 (m, 1H, py), 7.45 (m, 1H, py), 7.34 (m, 1H,
immediately recorded showing the formation of [Ru(η5-C5H5)(η3-
C5H4O-2-PPh3)(bn)]CF3SO3 (5). 1H NMR (δ, acetone-d6, 20 °C): 5.65
(m, 1H, H2), 4.81 (s, 5H, C5H5), 4.57 (d, 1H, H4, 2JHP ) 9.8 Hz), 3.88
(m, 1H, H1), 3.79 (t, 1H, H3). The resonances of coordinated PPh3
and benzonitrile were obscured by those of both free PPh3 and
benzonitrile. After a few minutes only the resonances of 4a and free
benzonitrile were observed.
3
3
4
py), 6.00 (ddd, 1H, H2, J12 ) 2.5 Hz; J34 ) 4.0 Hz, J24 ) 1.6 Hz),
4.56 (s, 5H, C5H5), 4.27 (m, 1H, H1, J12 ) 2.5 Hz, J13 ) 1.2 Hz),
3
4
3.80 (ddd, 1H, H3, 3J23 ) 4.0 Hz, JHP ) 5.3 Hz, J12 ) 1.2 Hz), 1.90
3
4
(dd, 1H, H4, 2JHP ) 10.8 Hz, 4J24 ) 1.6 Hz). The resonances of PBun
3
were superimposed by the signals of free phosphine. After a few
minutes additional resonances were observed due to the formation of
(6) Perrin, D. D.; Armarego, W. L. F. Purification of Laboratory
Chemicals, 3rd ed.; Pergamon: New York, 1988.

Coordinated Polyenes and Polyenyls
Inorganic Chemistry, Vol. 35, No. 20, 1996 5925
6a and liberated pyridine. For PCy3, only the formation of [Ru(η5-
C5H5)(η3-C5H4O-2-PCy3)(py)]CF3SO3 (9b) was observed. 1H NMR (δ,
acetone-d6, 20 °C): 9.12 (m, 1H, py), 8.33 (m, 1H, py), 7.90 (m, 1H,
py), 7.45 (m, 1H, py), 7.39 (m, 1H, py), 6.00 (m, 1H, H2), 4.59 (s, 5H,
C5H5), 4.36 (m, 1H, H1), 3.80 (m, 1H, H3). The resonances of H4 and
PCy3 were obscured by the proton resonances of free PCy3. Additional
resonances due to the formation of 6b and free pyridine were observed
after a few minutes. For PPhMe2, the formation of [Ru(η5-C5H5)(η3-
C5H4O-PPhMe2)(py)]CF3SO3 (9c) was observed. 1H NMR (δ, acetone-
d6, 20 °C): 9.14 (m, 1H, py), 8.33 (m, 1H, py), 7.88 (m, 1H, py),
7.72-7.66 (m, 5H, Ph), 7.49 (m, 1H, py), 7.38 (m, 1H, py), 5.81 (m,
1H, H2), 4.59 (s, 5H, C5H5), 3.71 (m, 1H, H1), 3.12 (m, 1H, H3), 2.14
This compound was synthesized analogously to 10a by treatment of 3
(300 mg, 0.636 mmol) with PMe3 (130 µL, 1.273 mmol). Yield: 201
mg (58%). Anal. Calcd for C15H22F3N2O4PRuS2: C, 32.91; H, 4.05;
N, 5.12; S, 11.71. Found: C, 33.35; H, 4.12; N, 5.17; S, 11.69. 1H
NMR (δ, acetone-d6, 20 °C): 7.69 (br, 4H, NH2), 5.58 (m, 1H, H2),
4.74 (s, 5H, C5H5), 4.04 (m, 1H, H1), 3.81 (d, 1H, H4, 2JHP ) 9.3 Hz),
2
3.24 (m, 1H, H3), 2.28 (d, 9H, JHP ) 12.1 Hz). 31P{1H} NMR (δ Vs
PPh3, acetone-d6, 20 °C): 28.6. IR (poly(chlorotrifluoroethylene),
cm-1): 1648 (s, νCdO).
Reaction of 3 with Tertiary Phosphines in CD3NO2. Typically a
5 mm NMR tube was charged with 3 (30 mg, 0.0636 mmol) and capped
with a septum. A solution of the tertiary phosphine (ca. 1.5 equiv) in
CD3NO2 (0.5 mL) was added by syringe, and the sample was transferred
to an NMR probe. 1H and 31P{1H} NMR spectra were immediately
2
(d, 6H, J ) 12.6 Hz), 1.98 (d, 1H, H4, JHP ) 10.2 Hz). Additional
resonances due to the formation of 6c and free pyridine were observed
after a few minutes. For PMe3, on addition of PMe3 (ca. 1.5 equiv) in
acetone-d6 by syringe, a pale yellow precipitate was immediately formed
which precluded the recording of an NMR spectrum.
recorded. For PBun , the formation of [Ru(η5-C5H4O)((1-4-η)-5-endo-
3
tu-C5H5)((PBun )]CF3SO3 (11a) and [Ru(η5-C5H5)(η3-C5H4O-
3
PBun )(tu)]CF3SO3 (10a) was observed. NMR for 11a: 1H (δ,
3
Attempted Reaction of 2 with PPh2Me, P(p-PhOMe)3, and PPh3.
A 5 mm NMR tube was charged with 2 (30 mg, 0.063 mmol) and
capped with a septum. A solution of either PPh2Me, P(p-PhOMe)3, or
PPh3 in acetone-d6 (0.5 mL) was added by syringe, the sample was
CD3NO2, 20 °C) 7.63 (br, 4H, NH2), 5.54 (m, 2H), 4.87 (m, 2H), 4.77
(m, 1H), 3.92 (m, 2H), 3.58 (m, 2H); 31P{1H} (δ vs PPh3, CD3NO2, 20
°C) 28.7. The proton resonances of PBun3 are superimposed by those
of the free phosphine. Additional resonances due to the formation of
6a and free thiourea were observed after a few minutes. For PMe3,
initially, only formation of [Ru(η5-C5H4O)((1-4-η)-5-endo-tu-
C5H5)(PMe3)]CF3SO3 (11b) was observed. 1H NMR (δ, CD3NO2, 20
°C): 7.58 (br, 4H, NH2), 5.55 (m, 2H), 4.90 (m, 2H), 4.55 (m, 1H),
1
transferred to an NMR probe, and H NMR spectra were recorded.
After 5 days, no reaction had occurred and >97% of 2 remained.
Reaction of 2 with Tertiary Phosphines in CD3NO2. A 5 mm
NMR tube was charged with 2 (30 mg, 0.063 mmol) and capped with
2
a septum. A solution of either PBun , PPhMe2, or PMe3 in CD3NO2
3.98 (m, 2H), 1.58 (d, 9H, JHP ) 13.8 Hz). The appearance of
3
additional resonances due to the formation of 6d, 7, and free thiourea
was observed after a few minutes.
(0.5 mL) was added by syringe, and the sample was transferred to an
NMR probe. 1H NMR spectra were immediately recorded. The poor
1
solubility of PCy3 in CD3NO2 precluded the recording of a H NMR
Reaction of 3 with Tertiary Phosphines in Acetone-d6. A 5 mm
NMR tube was charged with 3 (30 mg, 0.0636 mmol) and capped with
a septum. A solution of the tertiary phosphine (ca. 1.5 equiv) in
acetone-d6 (0.5 mL) was added by syringe, and the sample was
transferred to an NMR probe. 1H NMR spectra were immediately
1
spectrum. The H NMR spectra of PBun and PPhMe2 are similar to
3
those recorded in acetone-d6 showing the formation of intermediates
9a-c and 6a-c. For PMe3, the formation of [Ru(η5-C5H5)(η3-C5H4O-
2-PMe3)(py)]CF3SO3 (9d) was observed. 1H NMR (δ, CD3NO2, 20
°C): 9.03 (m, 1H, py), 8.29 (m, 1H, py), 7.93 (m, 1H, py), 7.51 (m,
1H, py), 7.26 (m, 1H, py), 5.971 (m, 1H, H2), 4.55 (s, 5H, C5H5), 4.28
(m, 1H, H1), 3.75 (m, 1H, H3). The resonance of H4 could not be
detected. Additional resonances due to the formation of 6d, 7, and
free pyridine were also observed.
recorded. For PBun , the formation of 10a was observed. Additional
3
resonances due to the formation of 6a and free thiourea were detected
after a few minutes. There was no indication of 11a being formed.
For PCy3, the formation of 10b was observed. After several minutes
additional resonances due to the formation of 6b and free thiourea were
observed. For PMe3, there was no evidence for the formation of either
11b, 10d, 6d, or 7; instead, the formation of several, as yet, not
identified compounds was observed.
Synthesis of [Ru(η5-C5H5)(η3-C5H4O-2-PBun )(tu)]CF3SO3 (10a).
3
To a solution of 3 (400 mg, 0.848 mmol) in CH3CN (7 mL), PBun
3
(0.315 mL, 1.273 mmol) was added, and the mixture was stirred for
10 min at room temperature whereupon a bright yellow precipitate was
formed. Diethyl ether was added, and the precipitate was collected on
a fritted glass funnel, washed with diethyl ether, and dried under
vacuum. Yield: 440 mg (77.0%). Anal. Calcd for C24H40F3N2O4-
PRuS2: C, 42.79; H, 5.98; N, 4.16; S, 9.52. Found: C, 42.53; H, 5.86;
N, 4.23; S, 9.44. 1H NMR (δ, CD3CN, 20 °C): 7.01 (br, 4H, NH2),
5.63 (m, 1H, H2), 4.63 (s, 5H, C5H5), 3.82 (m, 1H, H1), 3.24 (m, 1H,
Conversion of 10a-d to 6a-d. The reactions were performed on
a scale suitable for NMR experiments. Typically, 30 mg of these
respective complexes were dissolved in CD3CN (0.5 mL). The
solutions were transferred into an NMR tube and both the consumption
1
of 10a-d and the formation of 6a-d were monitored by H NMR
spectroscopy at various temperatures. Peak integration was with respect
to an internal CH2Cl2 standard.
2
H3), 3.00 (d, 1H, H4, JHP ) 8.4 Hz), 2.02 (m, 6H), 1.45 (m, 18H),
X-ray Structure Determination for 10a. Crystal data and experi-
mental details are given in Table 1. X-ray data were collected on a
Philips PW1100 four-circle diffractometer using graphite monochro-
mated Mo KR (λ ) 0.710 69 Å) radiation and the θ-2θ scan
technique. Three representative reference reflections were measured
every 120 min and used to correct for crystal decay and system
instability. Corrections for Lorentz and polarization effects were
applied. The structure was solved by direct methods.8 All non-
hydrogen atoms were refined anisotropically and hydrogen atoms were
included in idealized positions.9 The structures were refined against
F2. In order to compensate for the poor counting statistics of the
reflection data (small crystal), hard and soft restraints for bond lengths
and Uij were applied (idealized C5H5 ring; SADI.0001 bond length
0.92 (t, 9H). 31P{1H} NMR (δ Vs PPh3, acetone-d6, 20 °C): 37.9. IR
(poly(chlorotrifluoroethylene), cm-1): 1649 (s, νCdO).
Synthesis of [Ru(η5-C5H5)(η3-C5H4O-2-PCy3)(tu)]CF3SO3 (10b).
This compound was synthesized analogously to 10a by treatment of 3
(405 mg, 0.859 mmol) with PCy3 (361 mg). Yield: 509 mg (79.0%).
Anal. Calcd for C30H46F3N2O4PRuS2: C, 47.93; H, 6.17; N, 3.73; S,
8.53. Found: C, 47.71; H, 6.07; N, 3.80; S, 8.67. 1H NMR (δ, acetone-
d6, 20 °C): 7.73 (br, 4H, NH2), 5.72 (m, 1H, H2), 4.69 (s, 5H, C5H5),
3.92 (m, 1H, H1), 3.63 (d, 1H, H4, 2JHP ) 11.9 Hz), 3.50 (m, 1H, H3),
2.74 (q, 3H), 2.10-1.30 (m, 30H). 31P{1H} NMR (δ Vs PPh3, acetone-
d6, 20 °C): 41.3. IR (poly(chlorotrifluoroethylene), cm-1): 1644 (s,
ν
CdO).
restraints for chemically equivalent bonds in allyl, PBun , thiourea, and
Synthesis of [Ru(η5-C5H5)(η3-C5H4O-2-PPhMe2)(tu)]CF3SO3 (10c).
3
CF3SO3- moieties; SIMU and DELU soft restraints for the C5H5, PBun ,
This compound was synthesized analogously to 10a by treatment of 3
(200 mg, 0.424 mmol) with PPhMe2 (0.91 mL). Yield: 165 mg
(64.0%). Anal. Calcd for C20H24F3N2O4PRuS2: C, 39.41; H, 3.97;
N, 4.60; S, 10.52. Found: C, 39.53; H, 3.90; N, 4.77; S, 10.34. 1H
NMR (δ, CD3CN, 20 °C): 7.74 (br, 4H, NH2), 7.70-7.63 (m, 5H),
5.34 (m, 1H, H2), 4.57 (s, 5H, C5H5), 3.65 (m, 1H, H1), 3.30 (d, 1H,
3
and CF3SO3- moieties). The final full-matrix least-squares refinement
(7) Bevington, P. R. Data Reduction and Error Analysis for the Physical
Sciences; McGraw-Hill: New York, 1969.
(8) Hall, S. R.; Flack, H. D.; Stewart, J. M. XTAL3.2, Integrated System
of Computer Programs for Crystal Structure Determination; Universi-
ties of Western Australia (Australia), Geneva (Switzerland), and
Maryland (USA), 1992.
2
2
H4, JHP ) 7.6 Hz), 3.12 (m, 1H, H3), 2.03 (d, 6H, JHP ) 13.8 Hz).
31P{1H} NMR (δ Vs PPh3, acetone-d6, 20 °C): 31.7. IR (poly-
(chlorotrifluoroethylene), cm-1): 1652 (s, νCdO).
(9) Sheldrick, G. M. SHELXL93, Program for Crystal Structure Refine-
ment; University of Go¨ttingen: Go¨ttingen, Germany, 1993.
Synthesis of [Ru(η5-C5H5)(η3-C5H4O-2-PMe3)(tu)]CF3SO3 (10d).

5926 Inorganic Chemistry, Vol. 35, No. 20, 1996
Table 1. Crystallographic Data and Experimental Detailsa
Simanko et al.
formula
fw
cryst size, mm
space group
a (Å)
C24H40F3N2O4PRuS2
637.74
λ (Å)
0.71069
none
25
abs corr
0.05 × 0.16 × 0.44
P212121 (No. 19)
20.039(5)
13.726(4)
11.249(3)
3102(1)
θmax (deg)
index ranges
no. of reflns measd
no. of unique reflns
no. of reflns > 4σ(F)
no. of params
-22 e h 22, 0 e h e 15, 0 e l e 12
4957
4357
2611
b (Å)
c (Å)
V (Å-3
)
327
Z
F
4
R(F) (F > 4σ(F))
0.070
0.139
0.145
-0.40/0.44
calc (g cm-3
)
1.442
298
0.74
R(F) (all data)
T (K)
Rw(F2) (all data)
µ(Mo KR) (mm-1
)
diff fourier peaks min/max, e Å-3
2
4
a R(F) ) ||Fo| - |Fc||/|Fo|. Rw(F2) ) [w(Fo - Fc2)2/wFo ]0.5
.
Scheme 2
varied 327 parameters, applied 166 restraints, and used 4357 indepen-
dent reflections. Final positional parameters for all non-hydrogen atoms
are given in supporting information Table S1, positional and isotropic
displacement parameters for the hydrogen atoms appear in Table S2,
anisotropic displacement parameters for non-hydrogen atoms are in
Table S3, a full list of bond lengths and angles is given in Table S4,
and the parameters describing the least-squares planes are in Table S5.
Kinetic Studies of the Reaction between [Ru(η5-C5H4O)(CH3-
CN)]CF3SO3 (1a) and PPh3, P(p-PhOMe)3, and PPh2Me in Acetone.
The ambient pressure stopped-flow kinetic data were obtained with a
Hi-Tech SF-40 instrument. The optical signal at 400 nm was
monitored. The data were collected as sets of 2048 points, corre-
sponding to 3-4 half-lives, using a Physical Data Model 414A digitizer
and transferred to a DOS/Windows based personal computer for data
analysis. For particularly slow reactions, requiring more than 500 s of
data, the first 500 s of data were transferred to the computer and the
digitizer was retriggered. A stopwatch was used to measure the time
from mixing to the beginning of the second data set, and the data sets
were combined for analysis. The data all involved pseudo-first-order
conditions with the phosphine in large excess over the ruthenium
complex. The data were typically biphasic, showing a rapid absorbance
increase followed by a slower absorbance decrease. They were all fit
to a sum of two exponentials using either or both of two different
nonlinear least-squares procedures. One of the algorithms consisted
of the CURFIT routine of Bevington7 programmed in QuickBasic. The
other consisted of the Scientist data analysis package.
High-pressure stopped-flow measurements were made with a Hi-
Tech model HPS-2000 mixing system and the same spectrometer unit
and data acquisition system as used for the ambient pressure reactions.
The mixing system consists of a solenoid-powered, ratcheted drive for
2 mL glass-barreled syringes, a fused quartz cell, and a 5 mL waste
syringe. The flow system components were connected by Teflon valves
and tubing. This entire apparatus was placed in the pressure vessel.
Light is brought in and out through sapphire windows. A Pressure
Products Industries pump filled with Dow Corning 200 fluid (dimeth-
ylpolysiloxane) was used for pressurizing the stainless steel vessel. The
pressure vessel is kept in a thermostated bath at 25 °C, and the internal
temperature is monitored with a Pt resistance sensor. The high-pressure
apparatus gives a maximum of eight shots for each filling of the syringes
and pressurization of the system. Several pressures were measured
for each filling.
OH-2-PR3)]PF6 (PR3 ) PPh3 (4a), PPh2Me (4b), P(p-PhOMe)3
(4c)) reported earlier3d and will not be further discussed. It is
interesting to note, however, that in sharp contrast to 2, 1a reacts
with PMe3, PBun , PCy3, and PPhMe2 exclusively to give 1,1′-
3
disubstituted ruthenocenes.3d
The above reactions performed in acetone as the solvent led,
with the exception of PMe3, to the same products. Addition of
PMe3 to a solution of 2 in acetone affords a pale yellow
compound in essentially quantitative yield tentatively formulated
as [Ru(η5-C5H4O)((1-4-η)-5-endo-py-C5H5)(PMe3)]CF3SO3 (8a)
which is insoluble in this solvent (Scheme 2). In the solid state
8a can be handled for a short period of time but decomposition
occurs readily in solution (CD3NO2) to give a mixture of 2, 6d,
and 7. The proposed mechanism for the formation of 8a
involves nucleophilic attack of PMe3 at the metal center resulting
in an intramolecular migratory insertion of pyridine into the
cyclopentadienyl ring. The pyridinium ligand would, therefore,
1
be endo to the metal center. The H NMR spectrum is fully
Results and Discussion
consistent with a 5-pyridiniumylcyclopentadiene ligand (Figure
1). The assignment of the proton resonances was afforded by
homonuclear decoupling experiments. Unfortunately, the re-
cording of a 13C{1H} NMR spectrum was precluded due the
instability of this complex in solution. The IR spectrum exhibits
a strong C-H stretch at 2830 cm-1 assigned to the exo proton,
also suggesting that the pyridinium moiety is endo to the metal
center.10,11 The CdO peak is shifted from 1682 cm-1 in 2 to
Reactions of Tertiary Phosphines with [Ru(η5-C5H5)(η4-
C5H4O)(py)]CF3SO3 (2). The tertiary phosphines PBun , PCy3,
3
and PPhMe2 react with 2 in CH3NO2 to give, on workup, solely
1,2-disubstituted ruthenocenes 6a-c in high yields (Scheme 2).
The reaction of 2 with PMe3 is less selective and affords a 40/
60 mixture of 1,2-disubstituted and 1,1′-disubstituted ru-
thenocenes 6d and 7. By contrast, with PPh3, P(p-PhOMe)3,
and PPh2Me no reaction takes place, even upon prolonged
stirring at room temperature. The identity of the products has
been established by 1H NMR spectroscopy and elemental
analysis. The 1H NMR spectra of 6a-d are altogether similar
to those of the analogous complexes [Ru(η5-C5H5)(η5-C5H3-
(10) (a) Khand, I. U.; Pauson, P. L.; Watts, W. E. J. Chem. Soc. (C) 1969,
2024. (b) Green, M. L. H.; Pratt, L.; Wilkinson, G. J. Chem. Soc.
1959, 3753.
(11) Benfield, F. W. S.; Green, M. L. H. J. Chem. Soc., Dalton Trans.
1974, 1324.

Coordinated Polyenes and Polyenyls
Inorganic Chemistry, Vol. 35, No. 20, 1996 5927
centered at 3.00 (2JHP ) 8.4 Hz), 3.63 (2JHP ) 11.9 Hz), 3.30
(2JHP ) 7.6 Hz), and 3.81 (2JHP ) 12.1 Hz) ppm, respectively.
Similarly, the endo proton H4 of the structurally related
complexes [Mo(HBpz3)(CO)2(η3-C5H4O-PR3)]PF6 (HBpz3 )
tris(pyrazolyl)borate; PR3 ) PBun , PCy3) gives rise to a doublet
3
centered at 3.49 (2JHP ) 12.9 Hz) and 3.61 (2JHP ) 14.1 Hz),
respectively.14 The hydrogen atoms of the pyridine ligand are
magnetically inequivalent giving rise to five multiplets centered
at 9.19 (1H), 8.33 (1H), 7.93 (1H), 7.45 (1H), and 7.34 ppm
(1H), being indicative of a hindered rotation of pyridine about
the Ru-N axis. The resonances of the PBun moiety are
3
1
superimposed by those of the free phosphine. The H NMR
spectra of 9b-d show similar features and will not be discussed
here. Complexes 9, with the exception of 9d, are cleanly
converted to 6 within a few minutes (Scheme 2).
1
The H NMR spectroscopic results show that nucleophilic
attack takes place exclusively at the cyclopentadienone moiety
in an R-position to the ketonic functional group and from the
face opposite to the metal. The exo conformation of 9a-d in
solution, as drawn in Scheme 2, is also deduced from 1H NMR
evidence. In this conformation H4 is situated directly over the
pyridine ring. Due to anisotropic shielding by the aromatic ring
current of the pyridine ligand, the endo proton H4 experiences
a shift of about -1.7 ppm relative to those of the analogous
thiourea complexes 10a-d. Furthermore, the exo conformation
is consistent with the hindered rotation of pyridine.
1
Figure 1. 250 MHz H NMR spectrum of the polyene and polyenyl
part of [Ru(η5-C5H4O)((1-4-η)-5-endo-py-C5H5)(PMe3)]CF3SO3 (8a) in
CD3NO2.
1593 cm-1 in 8a, indicating loss of π-electron density from this
group to the ring and metal and, thus, a decrease in bond order.
Migratory insertions into C5H5 rings are rare but, nevertheless,
have been reported in the literature. For example, addition of
PMe3 to Mo(η5-C5H5)2(Et)(Cl) yields the endo-ethyl complex
Mo(η5-C5H5)((1-4-η)-5-endo-Et-C5H5)(PMe3)(Cl).11
Reactions of Tertiary Phosphines with [Ru(η5-C5H5)(η4-
C5H4O)(tu)]CF3SO3 (3). Treatment of 3 with PBun , PCy3,
3
PPhMe2, and PMe3 in CH3CN results in the formation of the
novel ruthenium(II) η3-cyclopentenoyl complexes 10a-d in
high yields (Scheme 2). 10a-d are bright yellow air stable
solids, whereas in solution conversion to 6a-d occurs within a
matter of hours. Characterization of these compounds has been
by elemental analyses, 1H and 31P{1H} NMR spectroscopy, and
IR spectroscopy. The structure of 10a, as determined by X-ray
crystallography, is shown in Figure 2. Selected bond lengths
and angles are given in the figure caption.
To obtain mechanistic information about the formation of 6a-
d, the reaction of 2 with PR3 (PR3 ) PBun , PCy3, PPhMe2,
3
PMe3) was monitored by H and 31P{1H} NMR spectroscopy
1
in both acetone-d6 and CD3NO2 as the solvents. This indicated
two observable parallel reactions: (i) reversible nucleophilic
attack of PR3 at the metal center affords 8a and 8b and (ii)
nucleophilic attack at the cyclopentadienone ligand to give
intermediate 9a-d (Scheme 2). Nucleophilic attack at the metal
center, however, is observed only for the sterically less
demanding yet very basic phosphines PMe3 and PBun3 yielding
The 1H NMR spectra of 10a-d all show the expected singlet
resonances for the C5H5 ring appearing in the range of 4.74-
4.57 ppm, while characteristic multiplet resonances assignable
to the allyl ligands are observed in the expected ranges. The
endo proton H4 is observed as a doublet in the range of 3.00-
3.81 ppm. In the IR spectra of 10a-d, the stretching frequency
of the ketonic carbonyl group is observed at 1649, 1644, 1652,
and 1648 cm-1, respectively, consistent with other cyclopen-
tenoyl complexes.4,5,15
8a and 8b, respectively. The nucleophilicity is taken to increase
12
in the order of increasing pKa PPhMe2 < PMe3 < PBun
<
3
PCy3, while the bulkiness of the phosphines, as expressed by
their cone angles,13 increases in the order PMe3 < PPhMe2 <
PBun < PCy3. Moreover, the formation of 6b appears to be
3
more pronounced in the more polar solvent CD3NO2 than in
acetone-d6.
The overall reaction of 3 with tertiary phosphines, as
The 1H NMR spectra of 9a-d all are very similar and, thus,
structural evidence will be discussed mainly with reference to
9a. The assignments of the proton resonances were aided by
detailed double resonance experiments. In the 1H NMR
spectrum of 9a, a sharp singlet at 4.56 ppm is observed for the
C5H5 ring; the resonance for the central allyl proton H2 appears
as a double double doublet centered at 6.00 ppm (3J34 ) 4.0
1
monitored by H NMR spectroscopy in CD3NO2, is similar to
the reactions of 2 with tertiary phosphines proceeding via the
intermediacy of η3-cyclopentenoyl complexes and will not be
further discussed. It is interesting to note, however, that with
PMe3 and to a lesser extent also with PBun , the formation of
3
[Ru(η5-C5H4O)((1-4-η)-5-endo-tu-C5H5)(PMe3)]CF3SO3 (11b)
and [Ru(η5-C5H4O)((1-4-η)-5-endo-tu-C5H5)(PBun )]CF3SO3
3
3
3
Hz, J12 ) 2.5 Hz, J2 ) 1.6 Hz). The resonances for the
(11a), respectively, is observed. Phosphine-promoted intramo-
lecular migratory insertions of either thiourea or pyridine into
C5H5 has no precedence in organometallic chemistry.
terminal allyl protons H1 and H3 appear as a multiplet and as a
double double doublet centered at 4.27 (3J12 ) 2.5 Hz, J14
)
)
4
1.2 Hz) and 3.80 ppm (3J23 ) 4.0 Hz, JHP ) 5.3 Hz, J12
3
4
1.2 Hz), respectively. The aliphatic endo proton H4 gives rise
Kinetic Studies
to a double doublet which is unusually upfield shifted to 1.90
The kinetics of the following three reactions were studied in
some detail, for PR3 ) PPh3, P(p-PhOMe)3, and PPh2Me (eq
4
ppm (2JHP ) 10.8 Hz, J24 ) 1.6 Hz). For comparison, the
respective resonance in 10a-d gives rise to a doublet
(14) Slugovc, C.; Mauthner, K.; Mereiter, K.; Schmid, R.; Kirchner, K.
Organometllics 1996, 15, 2954.
(15) (a) Kirchner, K.; Mereiter, K.; Schmid, R. J. Chem. Soc., Chem.
Commun. 1994, 161. (b) Kirchner, K.; Mereiter, K.; Umfahrer, A.;
Schmid, R. Organometallics 1994, 13, 1886.
(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.
(13) Tolman, C. A. Chem. ReV. 1977, 77, 313.

5928 Inorganic Chemistry, Vol. 35, No. 20, 1996
Simanko et al.
Figure 3. Absorbance Vs time data (left abscissa) at 400 nm for the
reaction of 1a with 0.48 M PPh3 at 35 °C. The data at the top (O) are
the residuals (right abscissa) between the fit curve and the data,
expanded 10-fold. The fit parameters are apparent rate constants of
4.8 × 10-2 and 0.55 s-1 and amplitudes of 0.53 and -0.34, respectively,
with an infinite time absorbance of 0.036.
Figure 2. Structural view of [Ru(η5-C5H5)(η3-C5H4O-2-PBun3)(tu)]CF3-
SO3 (10a). Selected bond lengths (Å) and angles (deg) are as follows:
Ru-S(1), 2.394(4); Ru-C(7), 2.226(11); Ru-C(6), 2.054(11); Ru-
C(10), 2.181(10); Ru-C(1-5)av, 2.199(10); C(8)-O(1), 1.219(13);
C(9)-P, 1.810(5); S(1)-C(23), 1.694(13); C(23)-N(1), 1.333(9);
C(7)-C(6)-C(10), 106.6(10); Ru-S(1)-C(23), 110.2(3); C(7)-C(8)-
C(9), 105.4(10).
1), and with acetone as the solvent. The reaction with PR3 )
and the extinction coefficient of the intermediate, ꢀin (eqs 3-7).16
PPh3 was studied for triphenylphosphine concentrations from
0.030 to 0.848 M and temperatures from 10 to 50 °C. A total
of 145 data sets representing 49 different conditions of tem-
perature and phosphine concentration were obtained and ana-
lyzed. The reaction with PR3 ) P(p-PhOMe)3 was studied for
phosphine concentrations from 5.1 to 120 mM and temperatures
from 10 to 50 °C. A total of 121 data sets representing 44
different conditions of temperature and phosphine concentration
were obtained and analyzed. In addition, the pressure depen-
dence of the reaction with PR3 ) P(p-PhOMe)3 was studied
for nine pressures (0.1-150 MPa) and seven phosphine
concentrations (5-120 mM) at 25 °C. A total of 148 data sets
representing 61 different conditions of pressure and phosphine
concentration were obtained and analyzed. For the reaction with
PPh2Me, phosphine concentrations ranged from 5.7 to 95.3 mM
and temperatures from 15 to 50 °C. A total of 118 data sets
representing 39 different conditions were studied. In all cases,
the absorbance Vs time data fit well to a sum of two exponen-
tials, a faster process accompanied by an absorbance increase
and a slower one which led to complete bleaching of the
absorbance. This gave two apparent rate constants and two
amplitudes for each data set. An example of the data and the
fit to it is given in Figure 3. The trends in the amplitude ratio
and apparent rate constants were fit according to the following
mechanism (eq 2).
p ) k1[PR3] + k-1 + k2
q ) (p2 - 4k1[PR3]k2)1/2
λ1 ) 0.5(p + q)
(3)
(4)
(5)
(6)
λ2 ) 0.5(p - q)
A1
A2
λ1 - k2
ꢀint
ꢀint
λ2 - k2
)
-
-
(7)
{(
)
( )} {( )
(
)}
λ1
ꢀ1a
/
ꢀ1a
λ2
The amplitude ratio was used in the fitting process in order to
eliminate the need to normalize the data for the slight changes
in the initial concentration of the ruthenium complex. The
extinction coefficients are assumed to be temperature indepen-
dent, and the temperature dependence of the rate constants is
given by the Eyring equation (eq 8)
ki ) (kBT/h)(exp(-(∆Hiq - T∆Siq)/RT)
(8)
where kB is the Boltzmann constant, R is the gas constant, h is
Planck’s constant, and T is the absolute temperature. The
pressure dependence of the rate constants is also expressed by
the Eyring form (eq 9)
This mechanism predicts two apparent rate constants, λ1 and
λ2, with their corresponding amplitudes A1 and A2. These
parameters can be expressed in terms of the rate constants of
the mechanism, the extinction coefficient at 400 nm for 1a, ꢀ1a,
(16) Espenson, J. H. Chemical Kinetics and Reaction Mechanisms;
McGraw-Hill Book Company: New York, 1981.

Coordinated Polyenes and Polyenyls
ki ) k0,i exp(-∆Viq/RT)
Inorganic Chemistry, Vol. 35, No. 20, 1996 5929
Table 2. Activation Parameters and Rate Constants at 25 °C for
the Reaction of [Ru(η5-C5H5)(η4-C5HO)(CH3CN)]CF3SO3 (1a) with
Tertiary Phosphines in Acetone
(9)
where k0 is the rate constant at ambient pressure, 0.1 MPa. The
results of fitting the two sets of temperature and concentration
dependent apparent rate constants are given in Table 2. The
∆Hq or ∆H°
parameter (kcal mol-1
∆Sq or ∆S°
phosphine
)
(cal mol-1 K-1
)
kc or K
11.6 ( 0.1 -22.5 ( 0.5 0.22 M-1 s-1
a
PPh3
k1
q
fit of the pressure and concentration dependent data gave ∆V1
k-1
k2
K1
20.6 ( 0.1
23.7 ( 0.2
-9.0
5.3 ( 0.4 0.074 s-1
q
of -2 ( 2 cm3 mol-1, V-1q of -18 ( 2 cm3 mol-1, and ∆V2
13.9 ( 0.5 0.029 s-1
of 8 ( 2 cm3 mol-1
.
-27.8
3.3 M-1
d
11.6 ( 0.1 -18.6 ( 0.2 1.70 M-1 s-1
a
P(p-PhOMe)3
k1
The quality of the fit is demonstrated by Figure 4, which
shows an example of a subset of the P(p-PhOMe)3 data at 30
°C. This demonstrates the nonlinear dependence of the two
apparent rate constants on phosphine concentration and the
complex variation of the amplitude ratio. The fit lines are
derived from the analysis of all of the data and reproduce the
kinetic behavior well. Figures S1-S4 are available as supporting
information and depict the concentration and temperature
dependence data for the P(p-PhOMe)3, PPh3, and PPh2Me
reactions and the pressure dependence data for the P(p-PhOMe)3
reaction. All data are also available as supporting information
(Tables S6-S9), with the conditions for each reaction, the
observed and calculated apparent rate constants, and the
amplitude ratios. The temperature dependence data are of
significantly higher quality than the pressure dependence data.
The origin of the scatter in the high-pressure data has not been
established.
k-1
k2
K1
20.9 ( 0.4
23.3 ( 0.1
-9.3
0.9 ( 1.0 0.0042 s-1
13.6 ( 0.2 0.050 s-1
-19.5
350 M-1
d
PPh2Meb
k1
13.1 ( 0.1 -13.9 ( 0.5 1.40 M-1 s-1
k-1
k2
K1
23.4 ( 0.5
21.3 ( 0.2
-10.3
9.7 ( 1.7 0.0061 s-1
6.1 ( 0.6 0.032 s-1
-23.6
250 M-1
d
a The ratio of the extinction coefficients, ꢀInt/ꢀ1a, is 4.2. b The ratio
of the extinction coefficients, ꢀInt/ꢀ1a, is 3.2. c Calculated from the
activation parameters. d Calculated from k1 and k-1
.
1
The proposed mechanism is strongly supported by the H
NMR measurements and the crystallography, as well as by
conformity with the rate law. The reaction of 1a and 1b with
PPh3, as monitored by 1H NMR spectroscopy, shows the
occurrence of an intermediate where the nitrile ligand is still
attached to the metal center. In the case of 1b, this intermediate
has been unequivocally identified as the η3-cyclopentoyl
complex [Ru(η5-C5H5)(η3-C5H4O-2-PPh3)(bn)]+. The charac-
teristic resonances of the cyclopentenoyl moiety give rise to
three multiplets centered at 5.65, 3.88, and 3.79 ppm while the
endo proton appears as a doublet centered at 4.75 ppm with
2JHP ) 9.8 Hz. The resonance of the C5H5 ring appears as a
singlet at 4.81 ppm. The resonances of the nitrile were
superimposed by those of the PPh3 ligand.
Figure 4. Dependence of the biexponential fit parameters on concen-
tration of phosphine for the reaction of 1a with P(p-PhOMe)3 at 30
°C. The lower rate constant, λ1 (0), and the higher rate constant, λ2
(O), are plotted against the left abscissa, and the amplitude ratio, A1/A2
(4), is plotted against the right abscissa. Each parameter at each
concentration is presented in triplicate. The solid lines are calculated
from the fit to all of the data, using the parameters in Table 2.
When the nitrile ligand is replaced by thiourea, the reactivity
is decreased and the trialkylphosphines attack the C5H4O ring.
Reaction with PBun3 leads to an isolabel intermediate, [Ru(η5-
C5H5)(η3-C5H4O-PBun )(tu)]CF3SO3 (10a), which has been
Table 3. Activation Parameters and Observed First-order Rate
Constants at 25 °C for the Conversion of
3
characterized crystallographically. The kinetics of the conver-
[Ru(η5-C5H5)(η3-C5H4O-2-PR3)(tu)]CF3SO3 (10a-d) to
[Ru(η5-C5H5)(η5-C5H3OH-2-PR3)]CF3SO3 (6a-d) in CD3CN
sion of 10a-d to 6a-d, analogous to step 2 in eq 2, has been
1
studied by H NMR spectroscopy in CD3CN as a function of
no.
T range
∆Hq
∆Sq
temperature. First-order rate constants at 25 °C and activation
parameters are given in Table 3. The rate constants and
activation parameters are essentially independent of the phos-
phine substituent.
conversion of pts ((1), °C (kcal mol-1
)
(cal mol-1 K-1 105k2 (s-1
) )
19a f 6a
10b f 6b
10c f 6c
10d f 6d
11
12
12
13
23-60
26-60
25-60
26-60
28.0 ( 0.8
28.3 ( 0.8
27.4 ( 0.8
27.7 ( 0.8
15.4 ( 0.6
15.4 ( 0.7
12.8 ( 0.5
12.5 ( 0.5
4.12 ( 0.2
2.67 ( 0.1
3.05 ( 0.1
1.73 ( 0.1
The thermal activation parameters show a consistent pattern.
The bimolecular first step, k1, has a large negative entropy, and
the last step, k2, involving the release of CH3CN, has a large
positive entropy. The reverse of the first step, k-1, shows a
near zero activation entropy, indicating that the transition state
still has a significant interaction with the outgoing phosphine
or that there are compensating rearrangements of the η4-C5H4O
which make a negative contribution to the entropy of activation,
balancing the positive contribution from phosphine release. The
activation parameters for k1 and k-1 can be combined to give
the equilibrium constant, and its associated enthalpy and entropy,
for the formation of the intermediate from the reactants. These
values are shown in Table 2. In all cases the reaction favors
the formation of the intermediate at room temperature with the
more basic phosphines leading to a more thermodynamically
stable compound. The highly favorable enthalpy of reaction
overcomes the unfavorable entropy contribution.
Further corroboration of the mechanism comes from the data
1
on the k2 step as monitored by H NMR spectroscopy. The
data in Table 2 are quite consistent with those in Table 3. The
entropy change is 14 ( 2 cal mol-1 K-1 for all six measure-
ments. The slower reactions involving 3 all have ∆Hq values
about 4 kcal mol-1 higher. This could very well come from
the stronger bonding of thiourea to the metal center compared
to CH3CN and might also include some solvent effect since
the NMR studies were done in CD3CN instead of acetone. The
k2 data from the reaction of 1a with PPh2Me show significantly
smaller entropy and enthalpy of activation. Compensating

5930 Inorganic Chemistry, Vol. 35, No. 20, 1996
Simanko et al.
effects lead to a room temperature rate constant that is quite
similar to that of the other two phosphines in Table 2. This
leads us to believe that there is little significant difference in
the PPh2Me reaction. The volume of activation data indicates
that there is relatively little change during the k1 step, but a
large negative change during the k-1 step. These two values
can be combined to give the difference in molar volume of 17
cm3 mol-1 between the η3-cyclopentenoyl intermediate and the
reactants. This is somewhat puzzling since bond formation has
occurred, but may be the result of the loosening of the η4-C5H4O
ring due to the shift to η3 coordination in the intermediate state.
The driving force of this reaction is presumably the stabilization
energy of the aromatic ring.
substitute on the C5H5 ring. This selectivity must be a result
of kinetic control since the more basic phosphines are reactive
enough to attack the C5H4O ring, as shown by the studies in
which the monodentate ligand is changed. When the leaving
group is pyridine or thiourea, the two rings are deactivated such
that only the C5H4O ring reacts, and it only reacts with the most
basic phosphines. In some of these cases an intermediate has
been observed in which the monodentate ligand has migrated
to the C5H5 ring while the entering nucleophile is coordinated
to ruthenium. This intermediate is formed reversibly and the
products obtained still involve substitution of the phosphine only
on the C5H4O ring.
Acknowledgment. Financial support by the “Fonds zur
Fo¨rderung der wissenschaftlichen Forschung” is gratefully
acknowledged (Project No. 11182).
Conclusions
This study has established the important details of the
mechanism by which phosphines attack a coordinated C5H4O
ring, to produce a coordinated η5-C5H3OH-2-PR3, including
detailed kinetic parameters. These values and patterns will form
the basis for the next steps in the study of these reactions. The
first priority is to study the reactions which lead to substitution
by phosphines on the C5H5 ring rather than at the C5H4O ring.
We have established that this is a function of the basicity of
the entering phosphine and the identity of the monodentate
leaving group. When the monodentate ligand is acetonitrile or
benzonitrile, only phosphines with a pKa of greater than 5
Supporting Information Available: Kinetic data that include
Figures S1-S4 showing the quality of the fit to the kinetic data as
plots of calculated Vs observed rate constants and amplitude ratios, as
well as Tables S6-S9, which list the conditions and all of the measured
rate constants and amplitude ratios as well as the fit values and tables
of crystallographic data that include listings of all atomic positional
and isotropic displacement parameters, anisotropic temeperature factors,
complete bond lengths and angles, and least-squares planes for complex
10a (Tables S1-S5) (30 pages). Ordering information is given on any
current masthead page.
IC960383V