Coordinatively Unsaturated 16-Electron Ruthenium Allenylidene Complexes: Synthetic, Structural, and Catalytic Studies

Article abstract of DOI:10.1021/om9906316

Summary: The one-pot reactions of [(p-cymene)RuCl₂]₂ (1) or (PPh₃)₄RuCl₂ (2) with 2 equiv of PCy₃ and 3,3-diphenylpropyn-3-ol afford the novel 16-electron ruthenium allenylidene complex (PC

Full text of DOI:10.1021/om9906316

Organometallics 1999, 18, 5187-5190
5187
Coor d in a tively Un sa tu r a ted 16-Electr on Ru th en iu m
Allen ylid en e Com p lexes: Syn th etic, Str u ctu r a l, a n d
Ca ta lytic Stu d ies
Hans-J o¨rg Schanz, Laleh J afarpour, Edwin D. Stevens, and Steven P. Nolan*,†
Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
Received August 6, 1999
Summary: The one-pot reactions of [(p-cymene)RuCl2]2
(1) or (PPh3)4RuCl2 (2) with 2 equiv of PCy3 and 3,3-
diphenylpropyn-3-ol afford the novel 16-electron ruthe-
nium allenylidene complex (PCy3)2Cl2Ru(dCdCdCPh2)
(3) in high yields. Substitution of one PCy3 ligand in 3
for one nucleophilic carbene ligand, IMes [1,3-bis(2,4,6-
trimethylphenyl)imidazol-2-ylidene], affords the novel
complex (PCy3)(IMes)Cl2Ru(dCdCdCPh2) (4). Single-
crystal X-ray structure analyses of complexes 3 and 4
were performed. Thermal stability of complexes 3 and 4
was investigated, and their catalytic activity promoting
ring-closing metathesis (RCM) of various substrates was
The nature of the carbene moiety has been proven to
affect not only the initiation but also the progression of
the catalytic process.1f Very common carbene moieties
are benzylidene (dCHPh) and vinylmethylene (dCH-
CHdCR2, R ) alkyl, aryl, H) groups. Due to their high
catalytic activities, benzylidene complexes have drawn
large attention and are commercially available.1f How-
ever, their synthesis from the hazardous diazoalkane
derivative is of concern. Vinylmethylene complexes are
less active, and their original preparation using cyclopro-
pane derivatives is cumbersome.1a However, the most
recent synthetic routes make use of propargyl chloride
derivatives.1l Catalytically active vinylidene complexes
(dCdCHR, R ) alkyl, aryl) were successfully prepared
by reaction of 1-alkynes with suitable precursors.6
Introducing an allenylidene moiety (dCdCdCR2, R
) Ph, Me) at the ruthenium center was successfully
carried out by using 3,3-diphenylpropyn-3-ol as reagent,
forming mostly cationic 18-electron complexes.7 Re-
cently, Hill and co-workers have reported a similar,
straightforward route for the synthesis of 16-electron
tested.
In tr od u ction
Ruthenium-based olefin metathesis catalysts have
been the focus of considerable attention since they are
relatively inert to air and moisture and show significant
tolerance to functional groups.1 Characteristic of these
five-coordinated, distorted square-pyramidal complexes
is the coordination of the ruthenium center, which is
comprised of chlorides in trans arrangement and trans-
phosphine ligands at the base of the pyramid with the
carbene moiety at the apex. The nature of the phosphine
ligation as well as that of the carbene moiety affects the
catalytic activity of the complex.1f
Widely used phosphine ligands are PCy3 and PPh3.
However, these complexes suffer from significant de-
composition at elevated temperatures.2 Nucleophilic
carbenes were found to mimic phosphines and were
employed in several organometallic catalytic reactions.3
Replacement of one phosphine ligand in these complexes
by the sterically demanding imidazol-2-ylidene ligand
IMes developed by Arduengo and co-workers4 not only
stabilizes the catalysts but also increases their activity
in metathesis reactions.5
ruthenium allenylidene complexes by reacting (PPh3)3-4
-
RuCl2 with 3,3-diphenylpropyn-3-ol.8 Recent investiga-
tions, however, have proven these complexes to be
3-phenyl-1-indenylidene complexes formed by intramo-
lecular rearrangement (Scheme 1).9 These complexes
perform well in metathesis reactions and show a high
thermal stability.8,10
† E-mail: snolan@uno.edu.
(1) (a) Nguyen, S. T.; J ohnson, L. K.; Grubbs, R. H. J . Am. Chem.
Soc. 1992, 114, 3974-3975. (b) Nguyen, S. T.; Grubbs, R. H.; Ziller, J .
W. J . Am. Chem. Soc. 1993, 115, 9858-9859. (c) Stumpf, A. W.; Saive,
E.; Demonceau, A.; Noels, A. F. J . Chem. Soc., Chem. Commun. 1995,
1127-1128. (d) Schwab, B.; France, M. B.; Ziller, J . W.; Grubbs, R. H.
Angew. Chem., Int. Ed. Engl. 1995, 34, 2039-2041. (e) Wu, Z.; Nguyen,
S. T.; Grubbs, R. H.; Ziller, J . W. J . Am. Chem. Soc. 1995, 117, 5503-
5511. (f) Schwab, B.; Grubbs, R. H.; Ziller, J . W. J . Am. Chem. Soc.
1996, 118, 100-110. (g) Herrmann, W. A.; Schattenmann, W. C.;
Nuyken, O.; Glander, S. C. Angew. Chem., Int. Ed. Engl. 1996, 35,
1087-1088. (h) Mohr, B.; Lynn, D. M.; Grubbs, R. H. Organometallics
1996, 15, 4317-4318. (i) Demonceau, A.; Stumpf, A. W.; Saive, E.;
Noels, A. F. Macromolecules 1997, 30, 3127-3136. (j) Diaz, E. L.;
Nguyen, S. T.; Grubbs, R. H. J . Am. Chem. Soc. 1997, 119, 3887-
3897. (k) Wilhelm, T. E.; Belderrain, T. R.; Brown, S. N.; Grubbs, R.
H. Organometallics 1997, 16, 3867-3869. (l) Ackermann, L.; Fu¨rstner,
A.; Weskamp, T.; Kohl, F. J .; Herrmann, W. A. Tetrahedron Lett. 1999,
40, 4787-4790.
Recently, we have synthesized several imidazol-2-
ylidene ruthenium 3-phenyl-1-indenylidene complexes
starting from the reaction of (PPh3)4RuCl2 with 3,3-
diphenylpropyn-3-ol.8,10 The addition was accompanied
by a rearrangement reaction forming the indenylidene
instead of the expected allenylidene moiety. We now
(2) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke R. J .
Principles and Applications of Organotransition Metal Chemistry, 2nd
ed.; University Science: Mill Valley, CA, 1987.
10.1021/om9906316 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 10/29/1999

5188 Organometallics, Vol. 18, No. 24, 1999
Notes
Sch em e 1
F igu r e 1. ORTEP diagram of (PCy3)2Cl2Ru(dCdCd
CPh2), 3.
3-phenyl-1-indenylidene complex 5. Starting from com-
plex 5, the PPh3 ligands can be substituted by the better
donating ligand such as PCy3, affording the analogous
indenylidene complex 6.9 Carrying out this reaction
under identical conditions with two additional equiva-
lents of PCy3, however, leads exclusively to the forma-
tion of the allenylidene complex 3. The C3 spine remains
intact, although water is also liberated in this reaction.
This can only be explained by the different ligation at
the metal center. The better donating PCy3 provides a
higher electron density at the ruthenium center. Obvi-
ously the rearrangement reaction forming the inde-
nylidene moiety is promoted by this lack of electron
density. Complex 3 is also accessible from the reaction
of [(p-cymene)RuCl2]2 (1) with 3,3-diphenylpropyn-3-ol
and 2 equiv of PCy3 via loss of p-cymene. However, the
product (85% of 3 based on 31P NMR data) contains two
side products, one identified as the 3-phenyl-1-inde-
nylidene complex 6 (1H and 31P NMR data, 8%) and one
unknown [7%, 31P NMR (C6D6, 25 °C, 121.4 MHz): δ )
37.4]. When 2 equiv of PPh3 instead of PCy3 were used,
no carbene moiety was formed. All attempts to convert
the allenylidene into the indenylidene by addition of
protic acids or by subjecting the allenylidene to elevated
temperatures were unsuccessful. The exchange of one
PCy3 ligand for IMes affords complex 4 in high yields.
The reactions are summarized in Scheme 1.
Single crystals of the complexes 3 and 4, suitable for
X-ray structure analysis, were obtained from slow
diffusion of hexanes into a saturated toluene solution
(ORTEP diagrams of 311 and 4 are given in Figures 1
and 2). In both structures the five-coordinated ruthe-
nium center is located at the bottom of a square
pyramid. The allenylidene moiety is located at the apex,
the trans chlorides and PCy3 ligands (3), PCy3 and IMes
ligands (4), form the base. In both complexes the Ru-
CR bond distances are nearly identical (1.794(11) Å).
This is in the usual range (1.76-1.84 Å) for carbene
moieties in this kind of 16-electron ruthenium com-
plexes.5 However, these bond distances are much shorter
than the bond lengths determined for cationic 18-
wish to report the syntheses and catalytic activity of
the first 16-electron ruthenium allenylidene complexes.
Resu lts a n d Discu ssion
The reaction of (PPh3)4RuCl2 (2) with 3,3-diphenyl-
propyn-3-ol results exclusively in the formation of the
(3) (a) For a comprehensive review see: Herrmann, W. A.; Ko¨cher,
C. Angew. Chem., Int. Ed. Engl. 1997, 36, 2163-2187. (b) Herrmann,
W A.; Goosen, L. J .; Spiegler, M. J . Organomet. Chem. 1997, 547, 357-
366. (c) Wolf, J .; Stu¨er, W.; Gru¨nwald, C.; Werner, H.; Schwab, P.;
Herrmann, W. A. Angew. Chem., Int. Ed. Engl. 1998, 37, 1124-1126.
(d) Weskamp, T.; Schattenmann, W. C.; Spiegler, M.; Herrmann, W.
A. Angew. Chem., Int. Ed. Engl. 1998, 37, 2490-2493. See also
corrigenda: Herrmann, W. A. Angew. Chem., Int. Ed. Engl. 1999, 38,
262. (e) Zhang. C.; Huang, J .; Trudell, M. L.; Nolan, S. P. J . Org. Chem.
1999, 64, 3804-3805.
(4) (a) Arduengo, A. J ., III; Harlow, R. L.; Kline, M. J . J . Am. Chem.
Soc. 1991, 113, 361-363. (b) Arduengo, A. J ., III; Gamper, S. F.;
Calabrese, J . C.; Davidson, F. J . Am. Chem. Soc. 1994, 116, 4391-
4393.
(5) (a) Huang, J .; Stevens, E. D.; Nolan, S. P.; Petersen, J . L. J . Am.
Chem. Soc. 1999, 121, 2674-2678. (b) Huang, J .; Schanz, H.-J .;
Stevens, E. D.; Nolan, S. P. Organometallics 1999, 18, 2370-2375.
(6) Katayama, H.; Ozawa, F. Organometallics 1998, 17, 5190-5196.
(7) (a) Selegue, J . Organometallics 1982, 1, 217-218. (b) Wolinska,
A.; Touchard, D.; Dixneuf, P. H.; Romero, A. J . Organomet. Chem.
1991, 420, 217-226. (c) Touchard, D.; Guesmi, S.; Bouchaib, M.;
Haquette, P.; Daridor, A.; Dixneuf, P. H. Organometallics 1996, 15,
2579-2583. (d) Gamasa, M. P.; Gimeno, J .; Gonzales-Bernardo, C.;
Borge, J .; Garcia-Granda, S. Organometallics 1997, 16, 2483-2485.
(e) Crochet, P.; Demerseman, B.; Vallejo, M. I. Organometallics 1997,
16, 5406-5415. (f) Tenorio, M. A. J .; Tenorio, M. J .; Puerta, M. C.;
Valerga, P. Organometallics 1997, 16, 5528-5535. (g) Estruelas, M.
A.; Gomez, A. V.; Lopez, A. M.; Modrego, J .; Onate, E. Organometallics
1997, 16, 5826-5835. (h) Fu¨rstner, A.; Picquet, M.; Bruneau, C.;
Dixneuf, P. H. J . Chem. Soc., Chem. Commun. 1998, 1315-1316. (i)
Werner, H.; Gru¨nwald, C.; Steinert, P.; Grevert, O.; Wolf, J . J .
Organomet. Chem. 1998, 565, 231-241. (j) Buriez, B.; Burns, I. D.;
Hill, A. F.; White, A. J . P.; Williams, D. J .; Wilton-Ely, J . D. E. T.
Organometallics 1999, 18, 1504-1516. (k) Cadierno, V.; Gamasa, M.
P.; Gimeno, J .; Iglesias, L.; Garcia-Granda, S. Inorg. Chem. 1999, 38,
2874-2879.
(8) (a) Harlow, K. J .; Hill, A. F.; Wilton-Ely, J . D. E. T J . Chem.
Soc., Dalton Trans. 1999, 285-291. (b) Fu¨rstner, A.; Hill, A. F.; Liebl,
M.; Wilton-Ely, J . D. E. T. J . Chem. Soc., Chem. Commun. 1999, 601-
603.
(9) Fu¨rstner, A.; Gabor, B.; Hill, A. F.; J afarpour, L.; Liebl, M.;
Mynott, R.; Nolan, S. P.; Wilton-Ely, J . D. E. T. J . Chem. Soc., Chem.
Commun., submitted.
(11) Crystals of compound 3 contain two conformers in the asym-
metric unit cell, differing only in allynylidene-phenyl torsion angles.
Only one is shown in Figure 1.
(10) J afarpour, L.; Schanz, H.-J .; Stevens, E. D., Nolan, S. P.
Organometallics, in press.

Notes
Organometallics, Vol. 18, No. 24, 1999 5189
Ta ble 1. Cr ysta llogr a p h ic Da ta for th e Com p lexes
(P Cy3)2Cl2Ru (dCdCdCP h 2) (3) a n d
(P Cy3)(IMes)Cl2Ru (dCdCdCP h 2) (4)
3
4
formula
fw
color
space group
a, Å
b, Å
C
51H76Cl2N2PRu
C54H67Cl2N2PRu
947.04
923.02
purple-brown
monoclinic, P21/n
31.391(3)
19.3287(16)
16.2623(13)
90
104.448(2)
90
5.40
purple-brown
monoclinic, P21/c
21.778(3)
10.1794(12)
23.736(3)
90
111.978(12)
90
5.01
c, Å
R, deg
â, deg
γ, deg
µ(Mo), cm-1
Z
8
4
Ra
Rw
0.0740
0.1484
0.0414
0.0427
a
no. of refined params
no. of data collected
no. of unique data, I > 2σ
Rmerge
1009
159173
27830
827
100274
14220
0.1385
0.0393
F igu r e 2. ORTEP diagram of (IMes)(PCy3)2Cl2Ru(dCd
CdCPh2), 4.
Ta ble 2. Selected Bon d Dista n ces [Å] a n d An gles
[d eg] for th e Com p lexes 3 a n d 4
(esd ’s a r e in p a r en th eses)
electron ruthenium allenylidene complexes (1.87-1.92
Å).7a,d,i-k This indicates a better overlap and a signifi-
cantly higher bond strength of the carbene moiety to
the metal center in complexes 3 and 4. The comparable
metal-ligand bond distances at the base also give very
similar values, indicating no significant change for the
electronic environment of the metal center, and these
structural features may explain the similar catalytic
properties of complexes 3 and 4 (see below). The bond
angles in both complexes at the base do not deviate more
than 4° from the ideal 90°. However, steric interference
with the allenylidene moiety causes widening of one CR-
Ru-Cl angle [96.2 (5)° (3), 95.89(4)° (4)] and one CR-
Ru-P angle (101.4(5)°) in complex 3 and the CR-Ru-
C(IMes) angle (98.89(5)°) in complex 4. The allenylidene
chain is only slightly bent in complex 4 (Ru-CR-Câ )
175.36(11)°, CR-Câ-Cγ ) 175.29(13)°). This indicates
a strong conjugation along the spine excluding C-H
π-interaction to neighboring hydrogen atoms, as ob-
served in other complexes.7j Complex 3, however, shows
significantly stronger bending along the spine (Ru-CR-
Câ ) 169.20(11)°, CR-Câ-Cγ ) 167.20(18)°). C-H
π-interaction to hydrogen atoms of the PCy3 ligands may
be present. The bond distances along the spine [CR-Câ
) 1.27 Å (3), 1.26 Å (4) and Câ-Cγ ) 1.35 Å (3), 1.34 Å
(4)] are in the usual range for ruthenium allenylidene
complexes.7a,d,i-k Selected bond distances and angles are
given in Table 2.
3
4
Ru-CR
1.794(11)
1.7932(13)
2.0893(14)
2.4107(4)
2.3640(4), 2.3916(4)
1.2605(17)
Ru-C(IMes)
Ru-P
2.358(5), 2.413(5)
2.371(5), 2.382(5)
1.273(12)
Ru-Cl
CR-Câ
Câ-Cγ
1.346(12)
1.3447(17)
98.89(5)
92.19(4)
93.13(4), 95.89(4)
88.94(3), 89.61(3)
88.056(14), 91.665(14)
CR-Ru-C(IMes)
CR-Ru-P
CR-Ru-Cl
C(IMes)-Ru-Cl
P-Ru-Cl
91.4(4), 101.4(5)
91.6(5), 96.2(5)
86.44(17), 87.56(17),
91.62(17), 92.62(16)
169.20(12)
Ru-CR-Câ
CR-Câ-Cγ
175.36(11)
175.29(13)
167.20(18)
Sch em e 2
Ta ble 3. Rin g-Closin g Meta th esis Med ia ted by
3 a n d 4
Th er m a l Sta bility. Compounds 3 and 4 were sub-
jected to elevated temperatures. The thermal stability
studies have been performed in NMR tubes by dissolv-
ing 5 mg of each compound in 0.4 mL of toluene-d8 and
heating the solution to 80 °C. The onset of decomposition
was noted by examining the 31P NMR spectra taken at
certain time intervals (2, 4, ..., 2n h). Both compounds
turned out to be relatively robust at this temperature.
Even after 32 h of constant heating no signs of decom-
position products were found. Initial signs of decomposi-
tion were noticed for complex 3 after 64 h and for com-
plex 4 after 128 h. A similar increased thermal stability
has been observed for the Cl2(PCy3)(IMes)Ru(dC(H)Ph
complex compared to Cl2(PCy3)2Ru(dC(H)Ph.5
entry
no.
catalyst
temp
(°C)
yield
(%)a
substrate precursor
solvent
CD2Cl2
CD2Cl2
CD2Cl2
CD2Cl2
toluene-d8
d8toluene-d8
time
1
2
3
4
5
6
7
7
8
8
9
9
3
4
3
4
3
4
40
40
40
40
80
80
25 min
25 min
25 min
25 min
2 h
12
8
4
0
0
2 h
0
a
Monitored by 1H NMR spectroscopy.
substrates, diethyl diallylmalonate (7), diallyltosylamine
(8), and diethyl di(2-methylallyl)malonate (9), were
added to the NMR tubes containing a solution of 5 mol
% of catalyst precursor in an appropriate deuterated
solvent. The catalytic reactions are depicted in Scheme
2, and results of the RCM reactions are presented in
Table 3.
Meta th esis Rea ction s. The role of complexes 3 and
4 as catalyst precursors in the ring-closing metathesis
(RCM) reactions was investigated. Three different diene
Product formation and diene disappearance were

5190 Organometallics, Vol. 18, No. 24, 1999
Notes
3,3-diphenylpropyn-3-ol (0.162 g/ 0.775 mmol) were dissolved
in 30 mL of THF and heated under reflux for 16 h. After cool-
ing to room temperature all volatiles were removed under
reduced pressure and the residue was suspended in 15 mL of
hexanes. After heating under reflux for an additional 3 h the
suspension was filtered and the yellow-brown residue was
washed with 3 × 5 mL of pentanes. Drying the residue in vacuo
for 30 min afforded 0.448 g (72%) of compound 3. 1H NMR
(300.1 MHz, 25 °C, C6D6): δ ) 8.03 (d, 4 H), 7.25 (t, 2 H), 7.06
(m, 4 H, CPh2), 2.83 (m, 6 H), 2.17 (m, 12 H), 1.65 (m, 30 H),
1.21 (m, 18 H, PCy3). 31P NMR (121.4 MHz, 25 °C, C6D6): δ )
40.9. IR (20 °C, CH2Cl2): ν (cm-1) ) 1925 (CdCdC). Anal.
Calcd for C51H76Cl2P2Ru: C, 65.46; H, 8.52. Found: C, 65.10;
H, 8.14.
monitored by integrating the allylic methylene peaks
in the H NMR. Both complexes perform very poorly in
1
these reactions compared to cationic 18-electron arene-
ruthenium allenylidene complexes.7h The significantly
higher bonding energy of the allenylidene moiety at the
metal center as inferred from the single-crystal X-ray
data may be at the origin of the lower catalytic activity
displayed by 3 and 4. The sterically hindered substrate
diethyl di(2-methylallyl)malonate shows no sign of ring
closing using either complex even after 2 h at 80 °C. To
get detectable conversion of the other substrates, reac-
tion mixtures were heated to 40 °C in CD2Cl2. The
turnover rates after 25 min indicated slightly lower
catalytic activity for the IMes-substituted complex 4
(diethyl diallylmalonate 8%, diallyltosylamine 0%) com-
pared to complex 3 (diethyl diallylmalonate 12%, dial-
lyltosylamine 4%).
Syn th esis of (IMes)(P Cy3)Cl2Ru (dCdCdCP h 2), 4. (PCy3)2-
Cl2Ru(dCdCdCPh2) (3, 0.7460 g/ 0.808 mmol) and IMes
(0.2610 g/0.857 mmol) were dissolved in 50 mL of toluene and
stirred at 40 °C for a period of 16 h. After cooling to room
temperature the reaction solution was filtered. The solvent of
the filtrate was removed under reduced pressure, and the
residue was suspended in 30 mL of hexanes. The mixture was
heated under reflux for 3 h and filtered after cooling to room
temperature. The residue was washed with pentanes (3 × 10
mL) and dried in vacuo for 30 min. Pure compound 4 was
Con clu sion s
The first coordinatively unsaturated 16-electron ru-
thenium allenylidene complex (PCy3)2Cl2Ru(dCdCd
CPh2) (3) is easily available from the one-pot reaction
of [(p-cymene)RuCl2]2 (1) or (PPh3)4RuCl2 (2) with 2
equiv of PCy3 and 3,3-diphenylpropyn-3-ol. The higher
electron density at the metal center provided by the
PCy3 ligands inhibits the rearrangement of the alle-
nylidene backbone. (PCy3)(IMes)Cl2Ru(dCdCdCPh2)
(4) can be obtained in high yields by simple ligand
exchange reaction with IMes starting from complex 3.
Both complexes possess a high thermal stability at 80
°C, with complex 4 being slightly more stable to
decomposition than complex 3. The single-crystal X-ray
data reveal very similar metal-ligand bond distances
in the solid state, indicating a similar electronic envi-
ronment at the metal center. Disappointingly low
catalytic activities for ring-closing metathesis reactions
were obtained for 3 and 4.
1
obtained as an orange-brown powder (0.602 g/79%). H NMR
(300.1 MHz, 25 °C, C6D6): δ ) 7.89 (d, 4 H), 7.28 (t, 2 H), 7.06
(m, 4 H, CPh2), 6.85 (s, 2 H), 6.28 (s, 2 H), 6.20 (d, 1 H), 6.14
(d, 1 H), 2. 58 (s, 6 H), 2.32 (s, 6 H), 2.14 (s, 3 H), 1. 72 (s, 3 H,
IMes), 2.50 (m, 3 H), 1.88 (m, 6 H), 1.47 (m, 9 H), 0.97-1.22
(m, 15 H, PCy3). 31P NMR (121.4 MHz, 20 °C, C6D6): δ ) 39.4.
IR (25 °C, CH2Cl2): ν (cm-1) ) 1924 (CdCdC). Anal. Calcd
for C54H67Cl2N2PRu: C, 68.48; H, 7.13; N, 2.96. Found: C,
68.46; H, 7.04; N, 3.00.
Gen er a l P r oced u r e for Th er m a l Sta bility Exp er i-
m en ts. In the drybox the catalyst precursor (5 mg) was
accurately weighed in a Wiland screw-capped NMR tube and
dissolved in toluene-d8 (0.4 mL). The solution was heated to
80 °C. The onset of decomposition was noted by examining the
31P NMR spectra taken at regular time intervals.
Gen er a l P r oced u r e for Rin g-Closin g Meta th esis. In the
drybox, the catalyst precursor (5.0 µmol/5 mol %) was ac-
curately weighed in a Wilmad screw-capped NMR tube and
dissolved in CD2Cl2 or toluene-d8 (0.4 mL). Diethyl diallylma-
lonate (0.1 mmol), diethyl di(2-methyl)allylmalonate (0.1
mmol), or diallyltosylamine (0.1 mmol) was added to the
solution, and the NMR tube was heated under argon. Product
formation and diene disappearance were monitored by inte-
grating the allylic methylene peaks.1k
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All synthesis and kinetic studies
were performed under inert atmospheres of argon using
standard high-vacuum or Schlenk tube techniques or in a
MBraun glovebox containing less than 1 ppm oxygen and
water. Solvents including deuterated solvents for NMR analy-
sis were dried and distilled under nitrogen before use employ-
ing standard drying agents. Compounds 112 and 213 and the
ligand IMes4 were synthesized according to literature proce-
dures. NMR spectra were recorded using a Varian Gemini 300
or Oxford 400 MHz spectrometer. IR spectra were performed
with a Perkin-Elmer System 2000 FT-IR. Elemental analyses
were performed by Desert Analysis, Tucson, AZ.
Syn th esis of (P Cy3)2Cl2Ru (dCdCdCP h 2) 3. Meth od A.
Bis(p-cymeneruthenium) tetrachloride (1.106 g/1.81 mmol) (1),
PCy3 (2.059 g/7.342 mmol), and 3,3-diphenylpropyn-3-ol (0.760
g/ 3.65 mmol) were dissolved in 50 mL of THF and heated
under reflux for 16 h. After cooling to room temperature all
volatiles were removed under reduced pressure and the residue
was suspended in 20 mL of hexanes. After heating under reflux
for an additional 3 h the suspension was filtered and the
yellow-brown residue was washed with 3 × 5 mL of pentanes.
Drying the residue in vacuo for 30 min afforded 1.465 g (44%)
of compound 3.
X-r a y Cr ysta llogr a p h ic Stu d ies. Deep red crystals of
complexes 3 and 4 were obtained by slow diffusion of hexane
into a saturated toluene solution. A single crystal of each
compound was placed in a capillary tube and mounted on a
Bruker SMART CCD X-ray diffractometer. Data were collected
using Mo KR radiation at 170 Κ. Cell dimensions were
determined by least-squares refinements of the measured
setting angles of 159 173 reflections with 2.50° < 2θ < 60.00°
for 3 and 100 274 reflections with 4.04° < 2θ < 60.00° for 4.
The structure was solved using direct methods (SHELXS-86)
and refined by full-matrix least-squares techniques. Crystal-
lographic data for both compounds are given in Table 1.
Ack n ow led gm en t. Financial support of this re-
search by the National Science Foundation is gratefully
acknowledged.
Meth od B. Tetrakis(triphenylphosphine)ruthenium dichlo-
ride (0.829 g/0.671 mmol) (2), PCy3 (0.435 g/1.550 mmol), and
Su p p or tin g In for m a tion Ava ila ble: Details of crystal
structure determinations for 3 and 4 (PDF) are provided. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(12) Bennett, M. A.; Huang, T. N.; Matheson, T. W.; Smith, A. K.
Inorg. Synth. 1982, 21, 74-79.
(13) Hallmann, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth.
1970, 12, 237-243.
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