Reversible Olefin-Hydride Insertion in the Cationic Ruthenium Complexes [(η6-C6H5CH2CH 2PR2)RuH(CH2=CH2)]+

Article abstract of DOI:10.1021/om0301987

Ruthenium-hydride olefin complexes having the formula [(η ⁶-C₆H₅CH₂CH₂PR ₂)RuH(CH₂= CH₂)][PF₆], where R = Cy (1) and Ph (2), were prepared via the reaction

Full text of DOI:10.1021/om0301987

1448
Organometallics 2004, 23, 1448-1452
Rever sible Olefin -Hyd r id e In ser tion in th e Ca tion ic
Ru th en iu m Com p lexes
[(η6-C6H5CH2CH2P R2)Ru H(CH2dCH2)]+
Kayo Umezawa-Vizzini and T. Randall Lee*
Department of Chemistry, University of Houston, 4800 Calhoun Road,
Houston, Texas 77204-5003
Received March 14, 2003
Ruthenium-hydride olefin complexes having the formula [(η6-C6H5CH2CH2PR2)RuH(CH2d
CH2)][PF6], where R ) Cy (1) and Ph (2), were prepared via the reaction of triphenylcar-
benium hexafluorophosphate (Ph3CPF6) with the corresponding (η6-C6H5CH2CH2PR2)Ru(CH3)2
complexes. Reversible olefin-hydride insertion reactions were directly observed for both 1
and 2 by 2D EXSY magnetic resonance experiments. The structure of complex 1 was
determined by X-ray crystallography.
In tr od u ction
studies. For ruthenium, however, examples of reversible
olefin-hydride insertion are extremely rare. Faller, for
example, observed the reversible insertion of styrene
into the Ru-hydride bond of the minor diastereomer of
[(p-cymene)RuH(CH2dCHPh)PR3][SbF6] (R ) Ph, OMe)
by magnetization transfer.11 Furthermore, Yi and Lee
found evidence of ethylene insertion into the Ru-H of
(PCy3)2(CO)(Cl)RuH upon treatment of the complex with
13C-labeled ethylene.12 In general, however, mono-
nuclear Ru-hydride olefin complexes are stable and
exhibit characteristically well-separated hydride chemi-
The insertion of carbon-carbon double bonds into
metal-hydride bonds occurs during many transition
metal-catalyzed transformations of olefins (e.g., olefin
hydrogenation, hydroformylation, and isomerization).1
From a fundamental point of view, the insertion of an
olefin into a metal-hydride bond is analogous to the
insertion of an olefin into a metal-alkyl bond, which
represents perhaps the most critical step in the catalytic
polymerization of olefins.2 Since the energy barrier for
olefin insertion into metal-hydride bonds is lower than
that for insertion into metal-alkyl bonds,3,4 relatively
few metal-hydride olefin complexes have been reported
in the literature; in contrast, metal-alkyl olefin com-
plexes are abundant.5,6
Of the known metal-hydride olefin complexes, most
exhibit reversible olefin-hydride insertion. For ex-
ample, reversible insertion has been directly observed
in a variety of organometallic complexes centered with
transition metals such as Mo,7 Co,3,4,8 Rh,3,4,9 Pt,10
Ru,11,12 Nb,13 and Ta14 using variable-temperature
nuclear magnetic resonance (NMR) spectroscopy, dy-
namic NMR spectroscopy, and magnetization-transfer
1
cal shifts by H NMR spectroscopy, which is consistent
with the absence of reaction between the hydride and
the olefin.15-17
Recently, much research has targeted the develop-
ment of Ziegler-Natta olefin polymerization catalysts
based on late transition metals such as Co,18-21
Ni,22-24,27-29 Pd,22-24 and Fe.18-21,25,26 In contrast, Ru-
based Ziegler-Natta polymerization catalysts have been
limited to a few example polymerizations of ethylene.30-32
For the past few years, we have been exploring the
(15) Kletzin, H.; Werner, H.; Serhadli, O.; Ziegler, M. L. Angew.
Chem., Int. Ed. Engl. 1983, 22, 46.
(16) Linder, E.; Pautz, S.; Fawzi, R.; Steimann, M. Organometallics
1998, 17, 3006.
* To whom correspondence should be addressed. E-mail: trlee@
uh.edu.
(1) See, for example: Ojima, I.; Eguchi, M.; Tzamarioudaki, M. In
Comprehensive Organometallic Chemistry; Abel, E. W., Ed.; Perga-
mon: New York, 1995; p 39.
(2) Siegbahn, E. M. J . Am. Chem. Soc. 1993, 115, 5803.
(3) Schmidt. G. F.; Brookhart, M. J . Am. Chem. Soc. 1985, 107, 1444.
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Principles and Applications of Organotransition Metal Chemistry;
University Science: Mill Valley, CA, 1987.
(17) Werner, H.; Kletzin, H.; Hohn, A.; Paul, W.; Knaup, W.; Ziegler,
M. L.; Serhadli, O. J . Organomet. Chem. 1986, 306, 227.
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1998, 120, 4049.
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J .; McTavish, S. J .; Solan, G. A.; White, A. J . P.; Williams, D. J . Chem.
Commun. 1998, 849.
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K. P.; White, A. J . P.; Williams, D. J . J . Chem. Soc., Dalton Trans.
2002, 6, 1159.
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10.1021/om0301987 CCC: $27.50 © 2004 American Chemical Society
Publication on Web 01/28/2004

Reversible Olefin-Hydride Insertion in Ru Complexes
Organometallics, Vol. 23, No. 6, 2004 1449
reaction of ruthenium alkyls with olefins in efforts
to develop ruthenium-based olefin polymerization
catalysts.33-36 Ruthenium not only is isoelectronic with
iron but is also known to initiate the ring-opening
metathesis polymerization (ROMP) of cyclic olefins
containing polar functional groups.37-42 In this paper,
we report that (η6-C6H5CH2CH2PR2)Ru(CH3)2, where R
) cyclohexyl (Cy) and phenyl (Ph), affords [(η6-C6H5-
CH2CH2PR2)RuH(CH2dCH2)][PF6] upon reaction with
triphenylcarbenium hexafluorophosphate (Ph3CPF6).
We describe the synthesis, structural characterization,
and direct observation of olefin-hydride insertion for
these cationic ruthenium complexes.
probably proceeds through the intermediacy of Ru-
methylidene and Ru-ethyl species. It has not been
established, however, whether the methylidene forma-
tion proceeds via radical processes such as that observed
during the formation of [Cp2WH(CH2dCH2)]+ from
Cp2W(CH3)2.44
Resu lts a n d Discu ssion
Using a procedure adapted from the literature,17
cationic ruthenium(II) complexes [(η6-C6H5CH2CH2PR2)-
RuH(CH2dCH2)][PF6] (1 and 2) were prepared by the
reaction of (η6-C6H5CH2CH2PR2)Ru(CH3)2 (R ) Cy and
Ph, respectively) with Ph3CPF6 in CH2Cl2 (eq 1). Upon
We performed an X-ray crystal structure analysis on
a single crystal of 1 obtained from the slow evaporation
of CH2Cl2. The resulting thermal ellipsoid plot and a
view perpendicular to the η6-aromatic ring are shown
in Figure 1; selected bond distances and angles are
listed in Table 1. The observed bond distance of Ru-H
was 1.47 ( 0.04 Å, which is similar in magnitude to that
of the related complexes [(η6-C6Me6)RuH(CH2dCH2)-
PPh3][PF6] (1.50 Å)15,16 and [(p-cymene)RuH(CH2d
CHPh)PPh3][SbF6] (1.44 Å).11 The bond distance is,
however, shorter than that found for other Ru-H
complexes, such as [RuH(C10H7)(dmpe)]+ (1.67 Å),45
RuHCl(PPh3)3 (1.68 Å),46 RuH(CCPh)(P(CH2CH2PPh2)3
(1.57 Å),47 and [(η6-C6H5PPh2)RuH(PPh3)2]+ (ca. 1.68
Å).48 Although the exact determination of metal hydride
positions by X-ray crystallography is not highly ac-
curate,5 the hydride observed here appears to reside at
substantial distances, 2.25 and 2.86 Å, from the ethylene
carbons, C1 and C2, respectively. Thus, we find no
evidence for agostic interactions between the hydride
and the olefin in the solid-state structure of 1.49
The bond distances between C1 and C2 (1.37 Å) and
those between the ethylenic carbons and ruthenium
(Ru-C1 and Ru-C2, both 2.20 Å) are similar to those
observed for [(η6-C6Me6)RuH(CH2dCH2)PPh3][PF6] (1.41
Å; 2.17 and 2.19 Å, respectively)15,16 and [(p-cymene)-
RuH(CH2dCHPh)(PPh3][SbF6] (1.40 Å; 2.20 and 2.22
Å, respectively).11 The equivalent Ru-C1 and Ru-C2
bond distances observed for 1 demonstrate that there
is no tilting of the olefin. The three ligands exist in a
staggered conformation relative to the coordinated
arene. The ruthenium metal lies beneath the center of
the coordinated arene. The bond distances from Ru to
each carbon of the coordinated arene are 2.23 Å (Ru-
C5), 2.29 Å (Ru-C6), 2.30 Å (Ru-C7), 2.32 Å (Ru-C8),
2.26 Å (Ru-C9), and 2.22 Å (Ru-C10). The slightly
elongated distances for Ru-C7, Ru-C8, and Ru-C9 are
probably constrained by the presence of the two-carbon
bridge.
crystallization by slow evaporation of CH2Cl2, compound
1 was obtained as light yellow crystal that were
insoluble in hexanes and diethyl ether, but slightly
soluble in benzene and THF. In separate experiments,
compound 2 was also isolated, but decomposed in CH2-
Cl2 during attempted recrystallizations. For both 1 and
-
2, the BF4 salts were prepared with similar results
(data not shown).
Analogous olefin hydride complexes were obtained by
Werner et al. by the reaction of (η6-C6H6)Os(CH3)2L (L
) CO, PMe3),17,43 (η6-C6Me6)RuPR3(CH3)2 (R3 ) Ph3,
Me3, MePh2),15-17 and CpIr(CH3)2P(i-Pr)3 with Ph3-
17
CPF6. The formation of 1 and 2 can be rationalized on
the basis of a previously proposed mechanism analogous
to that shown in eq 2.17,43 As illustrated, the reaction
(29) Liu, W.; Malinoski, J . M.; Brookhart, M. Organometallics 2002,
21, 2836.
(30) J ames, B. R.; Markham, L. D. J . Catal. 1972, 27, 442.
(31) Komita, S.; Yamamoto, A.; Ikeda, S. Bull. Chem. Soc. J pn. 1975,
48, 101.
(32) Momura, K.; Warit, S.; Imanishi, Y. Macromolecules 1999, 32,
4732.
(33) Umezawa-Vizzini, K.; Lee, T. R. Organometallics 1997, 16,
5613.
(34) Umezawa-Vizzini, K.; Lee, T. R. J . Organomet. Chem. 1999,
157, 122.
(35) Umezawa-Vizzini, K.; Lee, T. R. Organometallics 2003, 22,
3059.
(36) Umezawa-Vizzini, K.; Lee, T. R. Organometallics 2003, 22,
3066.
Additional characterization of the new complexes was
1
performed using H NMR (variable temperature), 13C
(37) Maughon, B. R.; Grubbs, R. H. Macromolecules 1997, 30, 3459.
(38) Hillmyer, M. A.; Gutierrez, E.; Grubbs, R. H. Macromolecules
1995, 28, 7256.
(39) Hillmyer, M. A.; Laredo, W. R.; Grubbs, R. H. Macromolecules
1995, 28, 6311.
(40) Grubbs, R. H. Macromolecules 1997, 30, 3978.
(41) Lynn, D. M.; Mohr, B.; Grubbs, R. H. J . Am. Chem. Soc. 1998,
120, 1627.
(42) Maynard, H. D.; Grubbs, R. H. Macromolecules 1999, 32, 6917.
(43) Roder, K.; Werner, H. Angew. Chem., Int. Ed. Engl. 1987, 26,
686.
(44) Hayes, J . C.; Cooper, N. J . J . Am. Chem. Soc. 1982, 104, 5570.
(45) Gregory, U. A.; Ibekwe, S. D.; Kilbourn, B. T.; Russel, D. R. J .
Chem. Soc. (A) 1971, 1118.
(46) Skapski, A. C.; Troughton, P. G. H. Chem. Commun. 1968, 1230.
(47) Bianchini, C.; Frediani, P.; Masi, D.; Peruzzini, M.; Zanobini,
F. Organometallics 1994, 13, 4616.
(48) McConway, J . C.; Skapski, A. C.; Phillips, L.; Young, R. J .;
Wilkinson, G. Chem. Commun. 1974, 327.
(49) Brookhart, M.; Green, M. L. H. J . Organomet. Chem. 1983, 250,
395.

1450 Organometallics, Vol. 23, No. 6, 2004
Umezawa-Vizzini and Lee
F igu r e 2. Variable-temperature 1H NMR spectrum of [(η6-
C6H5CH2CH2PCy2)RuH(CH2dCH2)][PF6], 1, in CD2Cl2. The
symbol (×) denotes residual diethyl ether resonances.
F igu r e 1. (A) Thermal ellipsoid plot of [(η6-C6H5CH2CH2-
PCy2)RuH(CH2dCH2)]+ (1) at the 40% probability level and
(B) a view perpendicular to the η6-aromatic ring.
Ta ble 1. Selected Bon d Len gth s [Å] a n d An gles
[d eg] for 1
Bond Lengths
Ru-H
1.47(4)
Ru-C(2)
Ru-C(10)
Ru-C(9)
Ru-P(1)
Ru-C(8)
2.195(4)
2.223(3)
2.257(3)
2.2950(8)
2.315(3)
Ru-C(1)
Ru-C(5)
Ru-C(6)
Ru-C(7)
C(1)-C(2)
2.199(4)
2.228(3)
2.286(3)
2.297(3)
1.367(6)
F igu r e 3. Variable-temperature 1H NMR spectrum of [(η6-
C6H5CH2CH2PPh2)RuH(CH2dCH2)][PF6], 2, in CD2Cl2. The
symbol (×) denotes residual diethyl ether resonances.
Bond Angles
H-Ru-C(2)
100.8(15)
36.26(15)
164.02(14)
126.4(15)
160.83(14)
87.7(15)
118.07(16)
66.41(13)
98.40(14)
65.61(12)
76.60(13)
90.71(10)
93.03(9)
126.40(10)
143.1(15)
98.85(14)
65.41(12)
35.86(12)
108.3(15)
96.14(15)
77.46(12)
64.46(12)
157.47(10)
72.0(2)
H-Ru-C(1)
72.7(15)
95.2(15)
1H COSY measurements of complex 1 demonstrated
that the extended multiplet over the range δ 2.34-2.71
can be assigned to the two-carbon bridge of the chelating
ligand, and the resonances at δ 2.35 and 2.89 can be
assigned to the coordinated ethylene ligand. Similarly,
C(2)-Ru-C(1)
C(2)-Ru-C(10)
H-Ru-C(5)
H-Ru-C(10)
C(1)-Ru-C(10)
C(2)-Ru-C(5)
C(10)-Ru-C(5)
C(2)-Ru-C(9)
C(10)-Ru-C(9)
H-Ru-C(6)
153.92(15)
128.53(14)
37.27(12)
142.87(14)
36.75(13)
160.8(15)
124.49(14)
36.49(12)
77.9(15)
C(1)-Ru-C(5)
H-Ru-C(9)
C(1)-Ru-C(9)
C(5)-Ru-C(9)
C(2)-Ru-C(6)
C(10)-Ru-C(6)
C(9)-Ru-C(6)
C(2)-Ru-P(1)
C(10)-Ru-P(1)
C(9)-Ru-P(1)
H-Ru-C(7)
1
variable-temperature H NMR measurements of com-
plex 2 showed that the resonances at δ 2.43 and 3.52
can be assigned to the two-carbon bridge, and the
resonances at δ 2.10 and 2.70 can be assigned to the
ethylene ligand. The coordinated arene ligands of
complexes 1 and 2 exhibit five resonances having
equivalent intensities at δ 6.7 (d), 6.5 (t), 6.1 (t), 6.0 (d),
and 5.4 (t) for complex 1 and at δ 6.8 (d), 6.7 (t), 6.2 (t),
6.0 (d), and 5.5 (t) for complex 2. In the 13C NMR spectra
of 1 and 2, the resonances at δ 35.89 and 35.39,
respectively, can be assigned to the carbon atoms of the
coordinated ethylene ligands.17,50
C(1)-Ru-C(6)
C(5)-Ru-C(6)
H-Ru-P(1)
C(1)-Ru-P(1)
C(5)-Ru-P(1)
C(6)-Ru-P(1)
C(2)-Ru-C(7)
C(10)-Ru-C(7)
C(9)-Ru-C(7)
P(1)-Ru-C(7)
C(2)-Ru-C(8)
C(10)-Ru-C(8)
C(9)-Ru-C(8)
C(7)-Ru-C(8)
C(2)-C(1)-Ru
106.35(12)
81.55(8)
102.40(8)
90.05(14)
76.76(13)
64.17(13)
137.65(9)
108.75(14)
65.17(13)
35.61(13)
35.54(13)
71.7(2)
C(1)-Ru-C(7)
C(5)-Ru-C(7)
C(6)-Ru-C(7)
H-Ru-C(8)
C(1)-Ru-C(8)
C(5)-Ru-C(8)
C(6)-Ru-C(8)
P(1)-Ru-C(8)
C(1)-C(2)-Ru
The variable-temperature 1H NMR spectra of com-
plexes 1 and 2 are shown in Figures 2 and 3, respec-
tively. Upon cooling to -30 °C, the broad Ru-H
resonances become sharp doublets (J HP ) 29.1 Hz for 1
and 25.2 Hz for 2). The large coupling constant suggests
that the hydride ligands exist as terminal hydrides
1
1
NMR, H-1H COSY, and H-13C COSY spectroscopic
1
measurements in CD2Cl2. At 0 °C, the H NMR spectra
of 1 and 2 exhibited broad resonances at δ -9.5 and
-8.6, respectively, which can be assigned to the Ru-H
moieties.15,17,43 Variable-temperature H NMR and H-
(50) Kletzin, H.; Werner, H. J . Organomet. Chem. 1985, 291, 213.
1
1

Reversible Olefin-Hydride Insertion in Ru Complexes
Organometallics, Vol. 23, No. 6, 2004 1451
â-hydride elimination,53 giving rise to exchange of the
hydride with all four ethylene hydrogens. We note,
however, that facile olefin rotation/hydride exchange
was selectively inhibited in a related system investi-
gated by Faller and co-workers, [(p-cymene)RuH-
(CH2dCHPh)PR3]+, where exchange was observed be-
tween the hydride and only the terminal olefinic
hydrogens.11 While the presence of the relatively bulky
phenyl ring in the latter system can plausibly block the
pathway to exchange of the remaining internal olefinic
hydrogen, electronic effects arising from the presence
of the phenyl moiety might also contribute to the
distinct reactivity of the Faller complexes compared to
that of 1 and 2.
F igu r e 4. 2D EXSY plot of [(η6-C6H5CH2CH2PCy2)RuH-
(CH2dCH2)][PF6], 1, in CD2Cl2 at -10 °C.
Support for olefin rotation in complexes 1 and 2 is
provided by their 1H NMR spectra (see Figures 2-5),
which exhibit two olefinic resonances rather than four.
Moreover, the two olefinic resonances showed no evi-
dence of broadening or splitting upon cooling to tem-
peratures as low as -60 °C (not shown), suggesting
facile olefin rotation with no detectable rotation barrier.
In contrast, a distinct barrier to olefin rotation was
observed in the Faller system at -50 °C (as indicated
by a broadening of the olefinic resonances upon cooling
to -50 °C and then a re-sharpening of these resonances
upon further cooling to -90 °C).11 It is plausible that
enhanced steric interactions (vide supra) and/or en-
hanced π-back-bonding (consistent with a longer C-C
bond distance of 1.40 Å for Faller’s R ) Ph complex vs
1.37 Å for complex 1) might be responsible for inhibiting
olefin rotation in the Faller system.
As described in the Introduction, the direct observa-
tion of olefin-hydride insertion in ruthenium hydride
olefin complexes is extremely rare,54,55 with only two
previous documented examples.11,12 It is interesting to
note that the barrier to olefin-hydride insertion is
apparently lower in 1 and 2 than in the nontethered
analogues [(η6-C6Me6)RuH(CH2dCH2)PR3][PF6], where
migratory insertion apparently fails to occur.15,17,56 It
is possible that electronic and/or steric effects imposed
by the two-carbon bridge play an important role in
promoting the olefin-hydride insertion observed for 1
and 2.57 In particular, the tethered analogues might
undergo insertion due to diminished π-back-bonding,
which is consistent with their shorter C-C bond dis-
tance (e.g., 1.41 Å for [(η6-C6Me6)RuH(CH2dCH2)PPh3]-
[PF6] vs 1.37 Å for complex 1).15,17
F igu r e 5. 2D EXSY plot of [(η6-C6H5CH2CH2PPh2)RuH-
(CH2dCH2)][PF6], 2, in CD2Cl2 at -30 °C.
rather than agostic species at this temperature.9 In
addition, cooling leads to a sharpening of the ethylene
resonances. By analogy to previous studies of related
metal hydride olefin complexes,7,9,11-13 we propose that
the hydride resonances are broad at room temperature
due to reversible olefin-hydride insertion, as illustrated
in eq 3.
To test this hypothesis, we performed at -10 °C (for
complex 1) and at -30 °C (for complex 2) 2D EXSY
experiments, which can be used to evaluate intramo-
lecular chemical exchange.51 The delay time (2 s) and
mixing time (1 s) used in these experiments were the
same for both complexes. Upon collection of the data,
correlations between Ru-H and the coordinated ethyl-
ene ligands were observed (see Figures 4 and 5). Since
the cross signals possess the same phase as the diagonal
signals, the cross signals cannot be assigned as NOESY
signals.52 Instead, the data provide direct evidence of
olefin-hydride exchange (i.e., olefin-hydride insertion
as in eq 3) within the complexes.51
In each of the 2D EXSY spectra shown in Figures 4
and 5, the cross-peaks between the hydride resonances
and both olefinic CH2 resonances suggest that olefin-
hydride exchange occurs at both ends of the olefin.
Consequently, we propose that the exchange pathway
involves olefin rotation in combination with insertion/
On the basis of these results, we believe that the
migratory insertion chemistry for related Ru-based
(53) For a recent Ni-based example of this process, see: Leatherman,
M. D.; Svejda, S. A.; J ohnson, L. K.; Brookhart, M. J . Am. Chem. Soc.
2003, 125, 3068.
(54) Ruthenium hydride olefin complexes are themselves quite rare.
A search of the Cambridge X-Ray Crystallographic Database revealed
only five mononuclear ruthenium hydride olefin complexes.11,15-17,55
All complexes except for that in ref 11 exhibited well-separated hydride
resonances at characteristic chemical shifts (δ -9 to -11) in their 1H
NMR spectra.
(55) Burn, M. J .; Frickes, M. G.; Hollander, F. J .; Bergman, R. G.
Organometallics 1995, 14, 137.
(56) Although Werner observed no evidence of olefin-hydride inser-
tion,15,17 we cannot fully exclude this pathway for the nontethered
analogues.
(57) Reactivity differences for ansa vs non-ansa systems are well
known (e.g., refs 35 and 36). For recent studies of related niobium and
tantulum olefin hydride complexes, see: Chirik, P. J .; Zubris, D. L.;
Ackerman, L. J .; Henling, L. M.; Day, M. W.; Bercaw, J . E. Organo-
metallics 2003, 22, 172. And: Ackerman, L. J .; Green, M. L. H.; Green,
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NMR Experiments, A Practical Course; Wiley-VCH: New York, 1998.

1452 Organometallics, Vol. 23, No. 6, 2004
Umezawa-Vizzini and Lee
Ta ble 2. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for 1
complexes can perhaps be tuned by appropriate modi-
fication of the ligand system utilized in the work
reported here. In particular, it might be possible to
prepare a modified ligand system that offers control over
â-hydride elimination, which could lead to new ruthe-
nium-based olefin polymerization catalysts.
empirical formula
fw
C22H36F6P2Ru
577.52
temperature
wavelength
cryst syst
223(2) K
0.71073 Å
monoclinic
space group
unit cell dimen
I 2/a
Con clu sion s
a ) 18.5840(6) Å, R ) 90°
b ) 7.9942(3) Å, â ) 101.994(1)°
c ) 32.5174(10) Å, γ ) 90°
4725.5(3) Å3
The reaction of (η6-C6H5CH2CH2PR2)Ru(CH3)2
with Ph3CPF6 in CH2Cl2 produced the cationic Ru(II)
complexes [(η6-C6H5CH2CH2PR2)RuH(CH2dCH2)][PF6],
where R ) Cy and Ph. The cationic complexes under-
went reversible olefin-hydride insertion, which was
directly observed by 2D EXSY magnetic resonance
experiments. The observation of this relatively rare
reaction should lend new insight toward the develop-
ment of ruthenium-based olefin polymerization cata-
lysts.
volume
Z
density(calcd)
abs coeff
F(000)
8
1.624 g/mL
0.854 mm-1
2368
cryst size
0.28 × 0.20 × 0.10 mm
θ range for data collection
limiting indices
no. of reflns collected
no. of indep reflns
abs corr
1.28-23.50°
-20 < h < 20, 0 < k < 8, 0 < l < 36
10 940
3780 (Rint ) 0.0243)
empirical
max. and min. transmn
refinement method
0.8349 and 0.7207
full-matrix least-squares on F2
Exp er im en ta l Section
data/restraints/parameters 3493/0/297
Ma ter ia ls a n d Meth od s. All solvents were dried by
passage through alumina and degassed by freeze-pump-thaw
methods prior to use. The compounds (η6-C6H5CH2CH2PCy2)-
Ru(CH3)2 and (η6-C6H5CH2CH2PPh2)Ru(CH3)2 were prepared
according to literature procedures.35,36 The compound Ph3CPF6
was purchased from Aldrich Chemical Co. Nuclear magnetic
resonance (NMR) spectra were recorded on a General Electric
QE-300 spectrometer operating at 300 MHz (for 1H) and 75.5
MHz (for 13C). Elemental analyses were performed by Oneida
Research Services. The 2D EXSY experiments were performed
using a published technique.52 Specifically, three 90° pulses
were applied and the delay time (2s) and mixing time (1s) were
selected.
goodness-of-fit on F2
final R indices [I>4σ(I)]
R indices (all data)
1.390
R1 ) 0.0284, wR2 ) 0.0524
R1 ) 0.0284, wR2 ) 0.0749
0.438 and -0.343
largest diff peak and hole
H, PPh2), 6.77 (d, J HH ) 6.0 Hz, 1 H, η6-C6H5), 6.66 (t, J HH
)
6.0 Hz, 1 H, η6-C6H5), 6.22 (t, J HH ) 6.0 Hz, 1 H, η6-C6H5),
6.01 (d, J HH ) 6.0 Hz, 1 H, η6-C6H5), 5.50 (t, J HH ) 6.0 Hz, 1
H, η6-C6H5), 3.52 (m, 2 H, C6H5CH2CH2P), 2.70 (m, 2 H, CH2d
CH2), 2.70 (m, 2 H, C6H5CH2CH2P), 2.10 (m, 2 H, CH2dCH2),
-8.6 (br s, 1 H, RuH). 13C NMR (CD2Cl2; 75.5 MHz; 293 K):
δ 129.5-133.0 (m), 124.30, 102.09, 95.96, 94.70, 91.74 (d, J CP
) 7.6 Hz), 90.80, 49.33 (d, J CP ) 35.5 Hz), 35.39 (CH2dCH2),
28.47. Due to facile decomposition, a satisfactory analysis was
not obtained. Anal. Calcd for C22H24RuP2F6: C, 46.70; H, 4.25.
Found: C, 45.79; H, 3.68.
Syn th esis of [(η6-C6H5CH2CH2P Cy2)Ru H(CH2dCH2)]-
[P F 6], 1. The starting material (η6-C6H5CH2CH2PCy2)Ru(CH3)2
(70.0 mg, 1.61 × 10-4 mol) was dissolved in 15 mL of CH2Cl2.
To this solution was added 1.0 equiv of Ph3CPF6 (62.6 mg, 1.61
× 10-4 mol). The mixture was stirred for 1 h. While stirring,
the color of the solution changed immediately to orange and
then became light yellow. The volume of the solution was
reduced to ca. 1 mL by evaporation. Diethyl ether was then
added to precipitate the product, which was collected by
filtration and recrystallized via slow evaporation of CH2Cl2.
Yield of light yellow crystals of 1: 60 mg (65%). 1H NMR
(CD2Cl2; 300 MHz; 273 K): δ 6.71 (d, J HH ) 6.9 Hz, 1 H, η6-
C6H5), 6.50 (t, J HH ) 6.9 Hz, 1 H, η6-C6H5), 6.07 (t, J HH ) 6.9
Hz, 1 H, η6-C6H5), 6.04 (d, J HH ) 6.9 Hz, 1 H, η6-C6H5), 5.40 (t,
J HH ) 6.9 Hz, 1 H, η6-C6H5), 2.50-2.71 (m, 4 H, C6H5CH2CH2P),
2.89 (m, 2 H, CH2dCH2), 2.35 (m, 2 H, CH2dCH2), 1.31-2.21
(m, 22 H, Cy2), -9.5 (br s, 1 H, RuH). 13C NMR (CD2Cl2; 75.5
MHz; 293 K): δ 122.86 (d, J CP ) 6.4 Hz), 101.87, 96.78, 94.78
(d, J CP ) 6.6 Hz), 92.24 (d, J CP ) 4.4 Hz), 90.72, 38.23 (d, J CP
) 28.3 Hz), 35.89 (CH2dCH2), 35.26 (d, J CP ) 30.6 Hz), 33.42
(d, J CP ) 22.3 Hz), 31.43, 29.28, 28.49, 27.93, 27.76, 27.58,
27.47, 26.30-27.20 (m). Anal. Calcd for C22H36RuP2F6: C,
45.75; H, 6.24. Found: C, 45.30; H, 6.10.
X-r a y Cr ysta l Str u ctu r e Deter m in a tion . All data were
collected using a Siemens SMART platform diffractometer
equipped with a 1K CCD area detector. A hemisphere of data
(1271 frames at 5 cm detector distance) was collected using a
narrow-frame method with scan widths of 0.30° in omega and
an exposure time of 30 s/frame. The first 50 frames were
remeasured at the end of data collection to monitor instrument
and crystal stability, and the maximum correction on I was <
1%. The data were integrated using the Siemens SAINT
program with the intensities corrected for Lorentz factor,
polarization, air absorption, and absorption due to variation
in the path length through the detector face plate. A psi scan
absorption correction was applied based on the entire data set.
Redundant reflections were averaged. Final cell constants were
refined using 7647 reflections having I > 10σ(I), and these,
along with other information pertinent to data collection and
refinement, are listed in Table 2.
Ack n ow led gm en t. The Robert A. Welch Founda-
tion (Grant E-1320) and the National Science Founda-
tion (CAREER Award to T.R.L. CHE-9625003) provided
generous support for this research. We thank Dr.
Charles Anderson for experimental design and technical
assistance with the NMR studies. We also thank Dr.
J ames Korp for assistance with the X-ray crystal-
lographic data collection and analysis.
Syn th esis of [(η6-C6H5CH2CH2P P h 2)Ru H(CH2dCH2)]-
[P F 6], 2. Compound
2
was prepared by dissolving (η6-
C6H5CH2CH2PPh2)Ru(CH3)2 (80.0 mg, 1.90 × 10-4 mol) in 15
mL of CH2Cl2. To this solution was added 1.0 equiv of Ph3-
CPF6 (73.7 mg, 1.90 × 10-4 mol). As the mixture was stirred
for 1 h, the color of the solution changed immediately to orange
and then became light yellow. After the volume of solution was
reduced to ca. 1 mL by evaporation, diethyl ether was added
to precipitate a tan-colored powder, which was collected by
filtration. Washing the tan-colored powder with THF afforded
a light yellow powder, which again became tan-colored upon
drying under vacuum. Yield of 2: 75 mg (70%). 1H NMR
(CD2Cl2; 300 MHz; 273 K): δ 7.48 (m, 8 H, PPh2), 7.35 (m, 2
Su p p or tin g In for m a tion Ava ila ble: CIF data for com-
plex 1. This material is available free of charge via the Internet
at http://pubs.acs.org.
OM0301987