Schiff base derivatives of ruthenium and osmium olefin metathesis catalysts

The present invention generally relates to ruthenium and osmium carbene catalysts for use in olefin metathesis reactions. More particularly, the present invention relates to Schiff base derivatives of ruthenium and osmium carbene catalysts and methods for making the same. The inventive catalysts are generally prepared by the treatment of unmodified catalysts with the salts of the desired Schiff base ligands, in which an anionic and a neutral electron donating ligands of the unmodified catalysts are simultaneously replaced. The Schiff base derivatives of the ruthenium and osmium carbene catalysts show unexpectedly improved thermal stability while maintaining high metathesis activity, even in polar protic solvents. Although the inventive catalysts may be used in all metathesis reactions, use of these catalysts for ring-closing metathesis ("RCM") reactions is particularly preferred.

BACKGROUND 
A large number of catalyst systems that can initiate olefin have been 
introduced. However, most early work in olefin was done using ill-defined 
multi-component catalyst systems. It is only in recent years that 
well-defined single component metal carbene complexes have been prepared 
and extensively utilized in olefin metathesis. 
With the advent of efficient catalyst systems, olefin metathesis has 
emerged as a powerful tool for the formation of C--C bonds in chemistry. 
Of importance among the well-defined catalyst systems is the alkoxy imido 
molybdenum system 1 developed by Schrock and co-workers and the 
benzylidene ruthenium carbene complexes 2-3 developed by Grubbs and 
co-workers. 
##STR1## 
In particular, the ruthenium carbene catalyst systems have drawn a lot of 
attention, not only because they exhibit high reactivity for a variety of 
metathesis processes under mild conditions, but also because of their 
remarkable tolerance of many organic functional groups. However, although 
these ruthenium carbene catalysts (particularly complexes 2 and 3) have 
been used in diverse olefin metathesis reactions with remarkable success, 
further improvements such as better thermal stability, high activity in 
polar protic solvents, and chiral and cis/trans selectivity, are required 
to more fully exploit their commercial potential. 
SUMMARY OF THE INVENTION 
The present invention generally relates to ruthenium and osmium carbene 
catalysts for use in olefin metathesis reactions. More particularly, the 
present invention relates to Schiff base derivatives of ruthenium and 
osmium carbene catalysts and methods for making the same. 
The Schiff base catalysts are of the general formula 
##STR2## 
wherein: M is ruthenium or osmium; 
X.sup.1 is an anionic ligand; 
L.sup.1 is a neutral electron donor; 
R and R.sup.1 are each hydrogen or a substituent selected from the group 
consisting of C.sub.1 -C.sub.20 alkyl, C.sub.2 -C.sub.20 alkenyl, C.sub.2 
-C.sub.20 alkynyl, aryl, C.sub.1 -C.sub.20 carboxylate, C.sub.1 -C.sub.20 
alkoxy, C.sub.2 -C.sub.20 alkenyloxy, C.sub.2 -C.sub.20 alkynyloxy, 
aryloxy, C.sub.2 -C.sub.20 alkoxycarbonyl, C.sub.1 -C.sub.20 alkylthio, 
C.sub.1 -C.sub.20 alkylsulfonyl and C.sub.1 -C.sub.20 alkylsulfinyl, the 
substituent optionally substituted with one or more moieties selected from 
the group consisting C.sub.1 -C.sub.10 alkyl, C.sub.1 -C.sub.10 alkoxy, 
and aryl; 
Z is selected from the group consisting of oxygen, sulfur,--NR.sup.10, and 
--PR.sup.10, and 
R.sup.6, R.sup.7, R.sup.8, R.sup.9, and R.sup.10 are each selected from the 
group consisting of hydrogen, C.sub.1 -C.sub.20 alkyl, aryl, and 
heteroaryl, each non-hydrogen group optionally substituted with one or 
more moieties selected from the group consisting of C.sub.1 -C.sub.10 
alkyl, C.sub.1 -C.sub.10 alkoxy, and aryl; 
wherein X.sup.1, L.sup.1, Z, R, R.sup.1, R.sup.6, R.sup.7, R.sup.8, and 
R.sup.9 each optionally includes one or more functional groups selected 
from the group consisting of hydroxyl, thiol, thioether, ketone, aldehyde, 
ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, 
carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen. 
The Schiff base ligands are prepared by the condensation of comprising 
contacting a salt of a Schiff base having the formula 
##STR3## 
with compound having the formula 
##STR4## 
wherein M, X.sup.1, L.sup.1, Z, R, R.sup.1, R.sup.6, R.sup.7, R.sup.8, and 
R.sup.9 are as previously described; 
X is an anionic ligand; and, 
L is a neutral electron donor. 
The Schiff base catalysts of the present invention show unexpectedly 
improved thermal stability over unmodified ruthenium and osmium catalysts, 
and maintain high metathesis activity even in polar protic solvents. 
Although the inventive catalysts may be used in all metathesis reactions, 
ring-closing metathesis ("RCM") reactions are particularly preferred since 
it is favored over other competing reactions at higher temperatures. In 
addition, because they provide convenient routes for including additional 
functionalities, Schiff base derivatives may play a key role in the design 
of chiral and/or cis/trans-selective metathesis catalysts.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention generally relates to ruthenium and osmium carbene 
catalysts for use in olefin metathesis reactions. More particularly, the 
present invention relates to Schiff base derivatives of ruthenium and 
osmium carbene catalysts and methods for making the same. 
Unmodified ruthenium and osmium carbene complexes have been described in 
U.S. Pat. Nos. 5,312,940, 5,342,909, 5,728,917, 5,750,815, and 2 5 
5,710,298, all of which are incorporated herein by reference. The 
ruthenium and osmium carbene complexes disclosed in these all possess 
metal centers that are formally in the +2 oxidation state, have an 
electron count of 16, and are penta-coordinated. These catalysts are of 
the general formula 
##STR5## 
wherein: M is ruthenium or osmium; 
X and X.sup.1 are each independently any anionic ligand; 
L and L.sup.1 are each independently any neutral electron donor ligand; 
R and R.sup.1 are each independently hydrogen or a substituent selected 
from the group consisting of C.sub.1 -C.sub.20 alkyl, C.sub.2 -C.sub.20 
alkenyl, C.sub.2 -C.sub.20 alkynyl, aryl, C.sub.1 -C.sub.20 carboxylate, 
C.sub.1 -C.sub.20 alkoxy, C.sub.2 -C.sub.20 alkenyloxy, C.sub.2 -C.sub.20 
alkynyloxy, aryloxy, C.sub.2 -C.sub.20 alkoxycarbonyl, C.sub.1 -C.sub.20 
alkylthio, C.sub.1 -C.sub.20 alkylsulfonyl and C.sub.1 -C.sub.20 
alkylsulfinyl. Optionally, each of the R or R.sup.1 substituent group may 
be substituted with one or more moieties selected from the group 
consisting of C.sub.1 -C.sub.10 alkyl, C.sub.1 -C.sub.10 alkoxy, and aryl 
which in turn may each be further substituted with one or more groups 
selected from a halogen, a C.sub.1 -C.sub.5 alkyl, C.sub.1 -C.sub.5 
alkoxy, and phenyl. Moreover, any of the catalyst ligands may further 
include one or more functional groups. Examples of suitable functional 
groups include but are not limited to: hydroxyl, thiol, thioether, ketone, 
aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, 
disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, 
and halogen. 
In preferred embodiments of these catalysts, the R substituent is hydrogen 
and the R.sup.1 substituent is selected from the group consisting C.sub.1 
-C.sub.20 alkyl, C.sub.2 -C.sub.20 alkenyl, and aryl. In even more 
preferred embodiments, the R.sup.1 substituent is phenyl or vinyl, 
optionally substituted with one or more moieties selected from the group 
consisting of C.sub.1 -C.sub.5 alkyl, C.sub.1 -C.sub.5 alkoxy, phenyl, and 
a functional group. In especially preferred embodiments, R.sup.1 is phenyl 
or vinyl substituted with one or more moieties selected from the group 
consisting of chloride, bromide, iodide, fluoride, --NO.sub.2, 
--NMe.sub.2, methyl, methoxy and phenyl. In the most preferred 
embodiments, the R.sup.1 substituent is phenyl. 
In preferred embodiments of these catalysts, L and L.sup.1 are each 
independently selected from the group consisting of phosphine, sulfonated 
phosphine, phosphite, phosphinite, phosphonite, arsine, stibine, ether, 
amine, amide, imine, sulfoxide, carboxyl, nitrosyl, pyridine, and 
thioether. In more preferred embodiments, L and L.sup.1 are each a 
phosphine of the formula PR.sup.3 R.sup.4 R.sup.5, where R.sup.3, R.sup.4, 
and R.sup.5 are each independently aryl or C.sub.1 -C.sub.10 alkyl, 
particularly primary alkyl, secondary alkyl or cycloalkyl. In the most 
preferred embodiments, L and L.sup.1 ligands are each selected from the 
group consisting of -P(cyclohexyl).sub.3, -P(cyclopentyl).sub.3, 
-P(isopropyl).sub.3, and -P(phenyl).sub.3. 
In preferred embodiments of these catalysts, X and X.sup.1 are each 
independently hydrogen, halide, or one of the following groups: C.sub.1 
-C.sub.20 alkyl, aryl, C.sub.1 -C.sub.20 alkoxide, aryloxide, C.sub.3 
-C.sub.20 alkyldiketonate, aryldiketonate, C.sub.1 -C.sub.20 carboxylate, 
arylsulfonate, C.sub.1 -C.sub.20 alkylsulfonate, C.sub.1 -C.sub.20 
alkylthio, C.sub.1 -C.sub.20 alkylsulfonyl, or C.sub.1 -C.sub.20 
alkylsulfinyl. Optionally, X and X.sup.1 may be substituted with one or 
more moieties selected from the group consisting of C.sub.1 -C.sub.10 
alkyl, C.sub.1 -C.sub.10 alkoxy, and aryl which in turn may each be 
further substituted with one or more groups selected from halogen, C.sub.1 
-C.sub.5 alkyl, C.sub.1 -C.sub.5 alkoxy, and phenyl. In more preferred 
embodiments, X and X.sup.1 are halide, benzoate, C.sub.1 -C.sub.5 
carboxylate, C.sub.1 -C.sub.5 alkyl, phenoxy, C.sub.1 -C.sub.5 alkoxy, 
C.sub.1 -C.sub.5 alkylthio, aryl, and C.sub.1 -C.sub.5 alkyl sulfonate. In 
even more preferred embodiments, X and X.sup.1 are each halide, CF.sub.3 
CO.sub.2, CH.sub.3 CO.sub.2, CFH.sub.2 CO.sub.2, (CH.sub.3).sub.3 CO, 
(CF.sub.3).sub.2 (CH.sub.3)CO, (CF.sub.3)(CH.sub.3).sub.2 CO, PhO, MeO, 
EtO, tosylate, mesylate, or trifluoromethanesulfonate. In the most 
preferred embodiments, X and X.sup.1 are each chloride. 
The catalysts of the present invention are similar to the above catalysts 
except that X and L are simultaneously substituted with a Schiff base 
ligand of the general formula 
##STR6## 
wherein: N and Z are coordinated to the metal center, M; 
Z is selected from the group consisting of O ("oxygen"), S ("sulfur"), 
NR.sup.10, and PR.sup.10 ; and 
R.sup.6, R.sup.7, R.sup.8, R.sup.9, and R.sup.10 are each independently 
selected from a group consisting of hydrogen, C.sub.1 -C.sub.20 alkyl, 
aryl, and heteroaryl. Each non-hydrogen group may be optionally 
substituted with one or more moieties selected from the group consisting 
of C.sub.1 -C.sub.10 alkyl, C.sub.1 -C.sub.10 alkoxy, and aryl which in 
turn may each be further substituted with one or more groups selected from 
halogen, C.sub..sub.1 -C.sub.5 alkyl, C.sub.1 -C.sub.5 alkoxy, and phenyl. 
The term "alkyl" is intended to be inclusive and thus includes all forms of 
alkyl moieties such as include primarly, secondary, tertiary, and cyclo 
alkyl groups. Illustrative examples of aryl and heteroaryl moieties 
include but are not limited to: anthracyl, adamantyl, furyl, imidazolyl, 
isoquinolyl, phenyl, naphthyl, phenantracyl, pyridyl, pyrimidyl, pyrryl, 
and quinolyl. Moreover, adjacent R groups, R.sup.6 and R.sup.7, may 
together form a substituted or unsubstituted cyclic group (i.e. aryl, 
cycloalkyl, or heteroaryl). Each of R.sup.6, R.sup.7, R.sup.8, R.sup.9, 
and R.sup.10 may be optionally substituted with one or more moieties 
selected from the group consisting of C.sub.1 -C.sub.10 alkyl, C.sub.1 
-C.sub.10 and aryl. In addition, the Schiff base ligand may include one or 
more functional groups. Examples of suitable functional groups include but 
are not limited to: hydroxyl, thiol, thioether, ketone, aldehyde, ester, 
ether, amine, amide, nitro, carboxylic acid, disulfide, carbonate, 
isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen. 
The resulting catalysts are of the general formula 
##STR7## 
wherein M, R, R.sup.1, R.sup.6, R.sup.7, R.sup.8, R.sup.9, Z, X.sup.1, and 
L.sup.1 are as previously defined. 
In preferred embodiments: M is ruthenium; R is hydrogen; R.sup.1 is 
selected from the group consisting of C.sub.1 -C.sub.20 alkyl, C.sub.2 
-C.sub.20 alkenyl, and aryl; L.sup.1 is a phosphine of the formula 
PR.sup.3 R.sup.4 R.sup.5 wherein R.sup.3, R.sup.4, and R.sup.5 are each 
selected from the group consisting of aryl, C.sub.1 -C.sub.10 primary 
alkyl, secondary alkyl, and cycloalkyl; and, X.sup.1 is selected from the 
group consisting of halide, CF.sub.3 CO.sub.2, CH.sub.3 CO.sub.2, 
CFH.sub.2 CO.sub.2, (CH.sub.3).sub.3 CO, (CF.sub.3).sub.2 (CH.sub.3)CO, 
(CF.sub.3)(CH.sub.3).sub.2 CO, PhO, MeO, EtO, tosylate, mesylate, and, 
trifluoromethanesulfonate. 
In more preferred embodiments, the inventive catalysts are of the general 
formula 
##STR8## 
wherein R, R.sup.1, R.sup.9, X.sup.1, and L.sup.1 are as previously 
defined, and R.sup.11 is an aryl or heteroaryl group, optionally 
substituted with one or more moieties selected from the group consisting 
of C.sub.1 -C.sub.10 alkyl, C.sub.1 -C.sub.10 alkoxy, and aryl. With 
reference to the general formula for the Schiff base catalyst derivative, 
M is ruthenium; Z is oxygen; R.sup.8 is hydrogen, and R.sup.11 is an aryl 
or heteroaryl group that is formed by the joining of R.sup.6 and R.sup.7. 
In even more preferred embodiments of the Schiff base complexes: 
X.sup.1 is chloride; 
L.sup.1 is selected from the group consisting of -P(cyclohexyl).sub.3, 
-P(cyclopentyl).sub.3, -P(isopropyl).sub.3, and -P(phenyl).sub.3 ; 
R is hydrogen; 
R.sup.1 is phenyl or vinyl, optionally substituted with one or more 
moieties selected from the group consisting of C.sub.1 -C.sub.5 alkyl, 
C.sub.1 -C.sub.5 alkoxy, and phenyl; 
R.sup.9 is an aryl or heteroaryl substituted with at least one moiety off 
its aromatic ring; and 
R.sup.11 is an aryl or heteroaryl substituted with at least one electron 
withdrawing group. In especially preferred embodiments, R.sup.9 is phenyl 
substituted with at least one bulky substituent and at least one electron 
withdrawing group, and R.sup.11 is phenyl substituted with at least one 
electron withdrawing group. Suitable examples of electron withdrawing 
groups include but are not limited to: halide, C.sub.1 -C.sub.10 alkyl 
substituted with one or more halides, and nitro. Suitable examples of 
bulky substituents include but are not limited to tertiary C.sub.3 
-C.sub.10 alkyl and aryl. 
Two of the most preferred embodiments of the present invention include: 
##STR9## 
In addition to being valuable in their own right, the chelate structure of 
the inventive Schiff base compounds provide a sufficiently rigid structure 
for the design of chiral and/or cis/trans-selective metathesis catalysts. 
For example, depending on the nature of the reaction, it may be desirable 
to have the catalyst be chiral or prochiral. Illustrative uses of such 
compounds include the kinetic resolution of chiral olefins and assymetric 
induction in prochiral triene ring closing reactions. 
Cis/trans-selectivity may be achieved by controlling the steric bulk of 
the ligands to influence the relative energies of the reaction 
intermediates that lead to different products. 
In another embodiment of the present invention, methods for preparing the 
Schiff base complexes are presented. In general the method reacting a salt 
of a Schiff base of the general formula 
##STR10## 
with a catalyst of the general formula 
##STR11## 
wherein M, R, R.sup.1, R.sup.6, R.sup.7, R.sup.8, R.sup.9, X, X.sup.1, L 
and L.sup.1 are as previously defined. 
Although any salt may be formed, thallium salts were found to be 
particularly effective. 
In preferred embodiments, the Schiff base is formed from the condensation 
of an aldehyde or a ketone of the general formula 
##STR12## 
with an amine of the general formula H.sub.2 NR.sup.9. 
In more preferred embodiments, the condensation reaction is between an 
aldehyde, R.sup.11 (HC.dbd.O)(OH), and an amine, H.sub.2 NR.sup.9, to 
yield catalysts of the general formula 
##STR13## 
wherein X.sup.1, L.sup.1, R, R.sup.1, R.sup.9, and R.sup.11 are as 
previously described. Particularly preferred aldehydes include substituted 
and unsubstituted salicylaldehyde. 
For the purposes of clarity, the synthesis of the Schiff base derivatives 
of ruthenium and osmium catalysts will be illustrated with reference to 
specific catalyst embodiments, ruthenium complex 2 or 3. However, it 
should be understood that the forthcoming methods are generally 
applicable. 
##STR14## 
As illustrated by Scheme 1, salicylaldimine ligands 6a-h were prepared by 
simple condensation of salicylaldehydes 4 and aliphatic or aromatic amine 
derivatives 5 in excellent yields. The salicylaldimine ligands were 5 
quantitatively converted to the corresponding thallium salts upon 
treatment with thallium ethoxide. The resulting Schiff base ligands were 
substituted for X and L ligands in complex 2 or 3. 
The efficiency of the substitution reactions to yield the desired Schiff 
base catalysts 8a-h varied depending on the bulk of the substituents on 
the ligands. For example, while thallium salts of ligands bearing a methyl 
group (7f) on the 6-position of the phenoxy part readily underwent 
substitution with 2 or 3, the reaction of ligands bearing bulkier 
substituents (i.e., t-Bu group) on the same position gave poor conversion 
under various substitution conditions. Reaction of 3 with ligands derived 
from anilines having number 2-and 6-substituents produced multiple 
complexes. However, presumably due to the steric reasons, ligands bearing 
highly bulky groups (i.e., triisopropylsilyloxy-) on the 2-and 6-position 
of benzimine exhibited relatively very poor reactivity in the reaction 
with 3. Nevertheless, the Schiff base ligand substitution described above 
is surprisingly robust and allows for the synthesis of a diverse set of 
Schiff base catalysts. 
Despite the quantitative conversion (by NMR) of 3 to the Schiff base 
ruthenium complexes in all cases, isolated recrystallization yields were 
lower due to the high solubility of the product complexes in most organic 
solvents. The ruthenium Schiff base benzylidene species 8a-h are very 
stable solids to air or moisture, and in some cases, can be further 
purified by column chromatography using silica gel. Moreover, the 
complexes show negligible amounts of decomposition in solution (CH.sub.2 
Cl.sub.2 or C.sub.6 H.sub.6), even when heated at temperatures as high as 
85.degree. C. For example, as shown by Table 1, although ruthenium complex 
3 (a representative example of a previously described ruthenium metathesis 
catalysts) decomposed significantly after only 30 minutes at 85.degree. 
C., inventive complex 8b was virtually unaffected. 
TABLE 1 
______________________________________ 
Comparisons of Catalyst Decomposition Rates 
complex 3 complex 8b 
______________________________________ 
Initial concentration 
4.2 mmoles 
4.0 mmoles 
30 minutes at 85.degree. 1.3 mmoles 3.6 mmoles 
60 minutes at 85.degree. 0.6 mmoles 3.8 mmoles 
______________________________________ 
As it will be explained in greater detail below, the unexpected increase in 
thermal stability of these catalysts over the previously described 
ruthenium and osmium metathesis catalysts makes them much more amenable to 
industrial applications. 
Structural Characterization of the Schiff Base Substituted Ruthenium 
Complexes. 
Substitution of one phosphine and one chloride ligand with a Schiff base 
ligand was unambiguously indicated by characteristic NMR spectral changes 
for all substitution reactions (7.fwdarw.8, Scheme 1). The coupling 
constants between the carbene proton H.alpha. and the coordinated 
phosphine has been found to be sensitive to the relative orientation of 
the plane defined by the atoms of the carbene fragment and that of the 
P-Ru-P plane. When the carbene plane is 90.degree. to the P-Ru-P plane, 
J.sub.PH =0 and J.sub.PH &gt;10 when they are coplanar. 
In contrast to complex 3 (singlet, 20.1 ppm in CD.sub.2 Cl.sub.2), the 
chemical shifts of the benzylidene proton in the compounds 8a-h appear 
between 19.8 and 18.7 ppm as doublet (Table 2). As expected, the complexes 
bearing ligands with more electron withdrawing substituents were shifted 
to more downfield. Proton-phosphorous couplings also varied depending on 
the nature of the Schiff base ligands. Especially noteworthy is that 
coupling constants J.sub.PH are more sensitive to the steric bulk rather 
than electronic contribution of the substituents on the Schiff base 
ligands. This suggest that although the ligand coordination around the 
ruthenium metal center is similar, the relative geometry of each species 
varies slightly depending on the steric demands caused by the ligands. For 
instance, while sterically crowded ligands give lower JPH coupling 
constants (i.e., 2.7 Hz in 8f), those values increase upon reduction of 
steric demands in the Schiff bases (i.e., 4.8 Hz in 8d). As found in the 
proton NMR spectroscopy, the .sup.31 P spectra for the coordinated 
phosphine ligands in 8a-h are also dependent on the electronic nature of 
the Schiff base ligands. For instance, while chemical shift of phosphorus 
is in the range of 51-54 ppm for aniline derived ligands, it is shifted to 
upfield (39 ppm) for 8h. 
TABLE 2 
______________________________________ 
NMR Data for Ruthium Carbene Complexes 
8a-8h and J (in Hz, CD.sub.2 Cl.sub.2) 
entry compound .sup.1 H.alpha. 
J.sub.HP 
.sup.31 P 
______________________________________ 
1 8a 19.68 3.6 52.23 
2 8b 19.77 3.3 52.23 
3 8c 19.49 4.7 50.51 
4 8d 19.48 4.8 50.62 
5 8e 19.39 4.5 50.65 
6 8f 19.69 2.7 53.50 
7 8g 19.72 3.3 52.54 
8 8h 18.68 13.5 38.95 
______________________________________ 
Representative of complexes 8a-h, the structure of the Schiff base 
substituted benzylidene species 8b was further confirmed by a single 
crystal X-ray analysis. The crystal suitable for X-ray structure 
determnination were isolated from concentrated diisopropyl ether solution 
at -20.degree. C. The data collection and refinement data of the analysis 
is summarized in Table 3 and selected bond distances and angles are listed 
in Table 4. 
TABLE 3 
______________________________________ 
Summary of Crystal Data and Structure Refinements of 8b 
______________________________________ 
Empirical formula 
C.sub.44 H.sub.60 ClN.sub.2 O.sub.3 PRu.0.31 CH.sub.2 
Cl.sub.2.0.17 H.sub.2 O 
Formula weight 863.53 
Crystal system Prismatic Monoclinic (dark brown) 
Space group P2.sub.1 /c (#14) 
Temperature 160K 
Unit cell dimensions a = 9.123 (4) .ANG. 
b = 24.320 (7) .ANG. 
c = 19.863 (5) .ANG. 
Z 4 
Volume 4405 (3) .ANG..sub.3 
.mu. 5.30 cm.sup.-1 (.mu.r.sub.max = 0.13) 
2.THETA. 3-5.degree. 
Crystal size (mm) 0.10 .times. 0.13 .times. 0.44 
Reflections measured 17106 
Independent reflections 7741 
Goodness-of-fit on F.sup.2 1.64 for 658 parameters and 7741 reflections 
Final R indices [F.sub.o ] 0.079 for 5735 reflections with F.sub.o.sup.2 
&gt;2.sigma.(F.sub.o.sup.2) 
Final weighted R [F.sub.o.sup.2 ] 0.121 for 7741 reflections 
______________________________________ 
TABLE 4 
______________________________________ 
Selected Bond Lengths (.ANG.) and Angles (deg) 
for Ruthenium Complex 8b 
______________________________________ 
Bond Lengths (.ANG.) 
Ru--C1 1.85 (6) P--C33 1.860 (6) 
Ru--O1 2.055 (4) P--C39 1.862 (6) 
Ru--N1 2.106 (4) O1-C20 1.288 96) 
Ru--P 2.345 (2) N1-C8 1.473 (7) 
Ru--C1 2.382 (2) N1-C14 1.301 (7) 
C1-C2 1.451 (8) C14-C15 1.433 (8) 
P--C27 1.864 (7) C1-H1 0.94 (6) 
(Carbene H) 
Bond Angles (degree) 
C1-Ru--O1 98.1 (2) C8-N1-Ru 121.5 (3) 
C1-Ru--N1 103.5 (2) C33-P--Ru 114.2 (2) 
O1-Ru--N1 88.9 (2) C39-P--Ru 117.5 (2) 
C1-Ru--P 96.8 (2) C27-P--Ru 102.4 (2) 
O1-Ru--P 88.4 (1) C33-P--C39 11.7 (3) 
N1-Ru--P 159.8 (1) C33-P--C27 103.9 (3) 
C1-Ru--C1 88.7 (2) C33-P--C27 105.2 (3) 
O1-Ru--C1 173.0 (1) O1-C20-C15 124.7 (5) 
P--Ru--C1 89.0 (1) N1-C14-C15 129.4 (5) 
Ru--C1-H1 113.1 (36) C2-C1-H1 111.6 (36) 
______________________________________ 
In the solid state, the molecule adopts a distorted trigonal bipyramidal 
coordination geometry. The bulky 2,6-diisopropyl benzimine occupies an 
axial position trans to the tricyclohexyl phosphine and the phenoxy part 
is positioned at an equatorial position with a nearly linear O1-Ru-Cl 
angle (173.0.degree.). The two aromatic rings of the Schiff base ligand 
are positioned with respect to each other at a 80.1.degree. angle. While 
the benzylidene moiety in complex 3 is perpendicular to the P1-Ru-P2 
plane, the angle of the carbene unit in the structure of 8b to the P-Ru-N1 
plane is 87.14.degree.. This distortion of the carbene plane is consistent 
with the nonzero value of J.sub.PH for 8b. The Ru-Cl (carbene carbon) bond 
distance [1.850(6).ANG.] are similar to those in related compounds; 
RuCl.sub.2 (.dbd.CHCH.dbd.CPh.sub.2)PCy.sub.3 [d(Ru-C), 1.851(21) .ANG.], 
[RuCl(.dbd.C(OMe)--(CH.dbd.CPh.sub.2)(CO)(Pi-Pr.sub.3).sub.2 ][BF.sub.4 
][d(Ru-C), 1.874(3).ANG.] or RuCl.sub.2 (.dbd.CH-p-C.sub.6 H.sub.4 Cl) 
(PCy.sub.3) .sub.2 [d(Ru-C), 1.838(3).ANG.]. 
Use of the Schiff Base Derivatives in Metathesis Reactions 
The inventive Schiff base catalysts may be used for any metathesis 
reaction. In general, methods for performing metathesis reactions comprise 
contacting at least one of the inventive catalyst with an olefin. Practice 
of the present invention may occur either in the presence or absence of 
solvents. In solventless reactions, the inventive catalysts typically 
dissolve in the olefin being reacted. As used herein, the term "olefin" is 
an unsubstituted or substituted hydrocarbon with at least one 
carbon-carbon double bond. The hydrocarbon may be straight-chain, 
branched, or a cyclic compound. Illustrative examples of hydrocarbon 
substituents include but are not limited to: C.sub.1 -C.sub.20 alkyl, 
C.sub.2 -C.sub.20 alkenyl, C.sub.2 -C.sub.20 alkynyl, aryl, C.sub.1 
-C.sub.20 carboxylate, C.sub.1 -C.sub.20 alkoxy, C.sub.2 -C.sub.20 
alkenyloxy, C.sub.2 -C.sub.20 alkynyloxy, aryloxy, C.sub.2 -C.sub.20 
alkoxycarbonyl, C.sub.1 -C.sub.20 alkylthio, C.sub.1 -C.sub.20 
alkylsulfonyl, C.sub.1 -C.sub.20 alkylsulfinyl, and a functional group 
selected from the group consisting of hydroxyl, thiol, thioether, ketone, 
aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, 
disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, 
and halogen. 
One particularly important metathesis reactions is ring opening metathesis 
polymerization ("ROMP") of cyclic olefins. Illustrative examples of cyclic 
olefins for ROMP include but are not limited to norborene, cyclobutene, 
norbornadiene, cyclopentene, dicyclopentadiene, cycloheptene, cyclooctene, 
7-oxanorbornene, 7-oxanorbornadiene, cyclooctadiene, and cyclododecene. 
Another important metathesis reaction is is ring closing metathesis 
("RCM). In RCM, a non-cyclic diene (an olefin having two carbon-carbon 
double bonds) is contacted with at least one of the inventive catalysts to 
form a cyclic olefin. Although the inventive catalysts may be used in any 
metathesis reaction, the use in RCM reactions is particularly preferred 
because it is favored over competing reactions at higher temperatures. 
Scheme 2 illustrates the use of the Schiff base ruthenium carbene complexes 
8a-h in an RCM reaction. 
##STR15## 
In general, the inventive compounds tend to be less reactive at room 10 
temperature than the previously described ruthenium and osmium carbene 
complexes. However, the reactivity increases dramatically at higher 
temperature. For instance, although the ring closure of diethyl 
diallylmalonate ester 9 proceeds in 12 hour at room temperature with 
complex 8g (8 mol %, CH.sub.2 C.sub.2), the reaction is completed in 1 
hour at 70.degree. C. with the same carbene catalyst (3 mol %, C.sub.6 
H.sub.6). In another example, the use of complex 8b results in nearly 100% 
yield when the reaction is carried at 55.degree. C. with no evidence of 
catalyst decomposition even after 2 days at that temperature. This high 
product yield is a surprising and unexpected result because of the number 
of competing pathways for diene reactants. 
The pronounced difference in reactivities between room and elevated 
temperatures poses several advantages to the industrial use of these 
catalysts. For example, the use of the Schiff base catalysts of the 
present invention presents an elegant and simple method for controlling 
the pot life (which is the time during which the monomer/catalyst mixture 
may be worked on) of the polymerization reaction mixture. Relying on the 
temperature dependent kinetics of the polymerization reaction, all the 
pre-polymerization steps for making a molded part (i.e mixing the olefin 
monomer with catalyst, casting/injecting/pouring the reaction mixture into 
a mold) can occur at room temperature. Since the inventive catalysts are 
not very active at this temperature, the preparatory steps can occur 
without fear of premature polymerization. Once the reaction is ready to 
proceed, the mixture can be heated to the necessary temperature to allow 
the polymerization reaction to occur at the desired rate. Suitable 
temperatures will depend on the specific inventive catalyst. However, the 
elevated temperature is typically at least about 40.degree. C. 
In another example, the catalysts of the present invention may be used for 
the formation large molded products. The polymerization of thick parts has 
been particularly problematic because the exothermic nature of the 
reaction tended to kill the previously described metathesis catalysts 
during the course of the polymerization reaction. As a result, 
polymerization of these products tended to be uneven with the centers of 
thick regions being especially susceptible to incomplete polymerization. 
In contrast, because of their increased thermal stability, such problems 
may be avoided with the use of the inventive catalyst. 
Yet another feature of the catalysts of the present invention is their 
ability to retain catalytic activity even in polar protic solvents. The 
use of polar protic solvents is necessary particularly when a desired 
substrate is not soluble in common nonpolar solvents. For example, 
diallylamine HCl salt 10 which is not soluble in common nonpolar solvents 
was cleanly cyclized in methyl alcohol with complex 8a (5 mol %, 
40.degree. C., 12 h). 
In summary, the Schiff base derivatives of ruthenium and osmium complexes 
are important catalysts in their own right exhibiting high thermal 
stability and high metathesis activity (even in polar protic solvents). In 
addition, because they provide convenient routes for including additional 
functionalities, Schiff base derivatives may play a key role in the design 
of chiral or cis/trans-selective olefin metathesis catalysts. 
Experimental Section 
Unless otherwise noted, all operations were carried out using standard 
Schlenk techniques or dry-box procedures. Argon was purified by passage 
through columns of BASF R3-11 catalyst (Chemalog) and 4 .ANG. molecular 
sieves (Linde). Solid organometallic compounds were transferred and stored 
in a nitrogen-filled Vacuum Atmospheres dry-box. .sup.1 H-NMR (300.1 MHz) 
and .sup.13 C-NMR (75.49 MHz) spectra were recorded on a General Electric 
QE-300 spectrometer. .sup.31 P-NMR (161.9 MHz) spectra were recorded on a 
JEOL GX-400 spectrometer. NMR Chemical shifts are reported in ppm 
downfield from tetramethylsulane ("TMS") (.delta. scale) with TMS employed 
as the internal solvent for proton spectra and phosphoric acid employed as 
the internal solvent for phosphorous spectra. High-resolution mass spectra 
were provided by the Southern California Mass Spectrometry Facility 
(University of California, Riverside). Analytical thin-layer 
chromatography ("TLC") was performed using silica gel 60 F254 precoated 
plates (0.25 mm thickness) with a fluorescent indicator. Flash column 
chromatography was performed using silica gel 60 (230-400 mesh) from EM 
Science. All solvents were rigorously degassed in 18 L reservoirs and 
passed through two sequential purification columns. Complex 3 and 
2,6-dimethyl-4-methoxyaniline were prepared according to published 
procedures (Nguyen et al., J Am. Chem. Soc. 115: 9858-9859 (1993); Sone et 
al., Nippon Kagaku Kaishi 7 1237-1240 (1982)). Unless otherwise noted, all 
other compounds were purchased from Aldrich Chemical Company and used as 
received. 
General Procedure for Preparation of Schiff Base (6a-h). 
The condensation of salicylaldehydes with aliphatic or aromatic amine 
derivatives were carried out with stirring in ethyl alcohol at 80.degree. 
C. for 2 hours. 
Upon cooling to 0.degree. C., a yellow solid precipitated from the reaction 
mixture. 
The solid was filtered, washed with cold ethyl alcohol and then dried in 
vacuo to afford the desired salicyladimine ligand in excellent yields. Any 
modifications are described for each reaction. 
Schiff Base 6a (R.sup.1 =H, R.sup.2 =2,6-i-PrC.sub.6 H.sub.3): 
Salicylaldehyde (0.37 g, 3.0 mmol), 2,6-diisopropylaniline (0.53 g, 3.0 
mmol) and ethanol (15 mL) afforded 0.76 g (90%) of the title compound as a 
yellow solid. A drop of formic acid was used to accelerate the 
condensation reaction. mp. 60-61.degree. C.; .sup.1 H-NMR (CDCl.sub.3) 
.delta. 13.16 (s, 1H), 8.34 (s, 1H), 7.46 (d, J=7.2 Hz, 1H), 7.40 (t, 
J=7.2 Hz, 1H), 7.22 (bs, 3H), 7.10 (d, j=8.4 Hz, 1H), 6.99 (t, J=7.5 Hz, 
1H), 3.20 (septet, J=6.6 Hz, 2H), 1.20 (d, J=6.9 Hz, 12H); .sup.13 C-NMR 
(CDCl.sub.3).delta. 166.4, 161.0, 145.9, 138.4, 133.0, 132.0, 125.3,123.0, 
118.8, 118.4, 117.1, 27.9, 23.3; HRMS (EI) for C.sub.19 H.sub.23 NO 
[M].sup.+ 281.1780, found 281.1786. 
Schiff Base 6b (R.sup.1 =4-NO.sub.2, R.sup.2 =2,6-i-PrC.sub.6 H.sub.3): 
5-Nitrosalicylaldehyde (1.10 g, 6.60 mmol), 2,6-diisopropylaniline (1.20 g, 
6.60 mmol) and ethanol (25 mL) afforded 2.0 g (93%) of the title compound 
as a yellow solid. mp. 122-124.degree. C.; .sup.1 H-NMR (CDCl.sub.3) 
.delta. 14.35 (s, 1H), 8.43 (s, 1H), 8.38 (d, J=2.7 Hz, 1H), 8.32 (d, 
J=9.3 Hz, 1H), 7.25 (bs, 3H), 7.15 (d, J=9.0 Hz, 1H), 2.97 (septet, J=6.9 
Hz, 2H), 1.22 (d, J=6.9 Hz, 12H); .sup.13 C-NMR (CDCl.sub.3) .delta. 
166.8, 165.2, 144.4, 139.7, 138.4, 128.3, 128.2, 126.1, 123.3, 118.3, 
117.3, 28.1, 23.3; HRMS (CI) for C.sub.19 H.sub.23 N.sub.2 O.sub.3 
[M+H].sup.+ 327.1709; found 327.1708. 
Schiff Base 6c (R.sup.1 =4-NO.sub.2, R.sup.2 =2,6-Me-4-MeOC.sub.6 H.sub.2): 
5-nitrosalicylaldehyde (6.68 g, 40 mmol), 2,6-dimethyl-4-methoxyaniline 
(6.65 g, 44 mmol) and ethanol (140 mL) afforded 11.52 g (96%) of the title 
compound as a yellow solid. mp. 122-124.degree. C.; .sup.1 H-NMR 
(CDCl.sub.3) .delta. 14.67 (s, 1H), 8.41 (s, 1H), 8.33 (d, J=2.7 Hz, 1H), 
8.28 (dd, J=9.1, 2.7 Hz, 1H), 7.10 (d, J=9.1 Hz, 1H), 6.68 (s, 2H), 3.81 
(s, 3H), 2.24 `(s, 6H); .sup.13 C-NMR (CDCl.sub.3) .delta. 167.6, 165.0, 
157.3, 130.2, 128.3, 128.2, 118.5, 117.5, 113.9, 55.4, 18.9; HRMS (CI) for 
C.sub.16 H.sub.17 N.sub.2 O.sub.4 [M.sup.+ H]+ 301.1188, found 301.1196. 
found 301.1196. 
Schiff Base 6d (R.sup.1 =4-NO.sub.2, R.sub.2 =2,6-Me-4-BrC.sub.6 H.sub.2): 
5-Nitrosalicylaldehyde (0.67 g, 4.0 mmol), 4-bromo-2,6-dimethylaniline 
(0.80 g, 4.0 mmol) and ethanol (15 mL) afforded 1.41 g (91%) of the title 
compound as a yellow solid. mp. 194-196.degree. C.; .sup.1 H-NMR 
(CDCl.sub.3) .delta. 13.96 (s, 1H), 8.41 (s, 1H), 8.35 (d, J=2.7 Hz, 1H), 
8.30 (d, J=9.0 Hz, 1H), 7.28 (s, 2H), 7.13 (d, J=9.0 Hz, 1H), 2.19 (s, 
6H); .sup.13 C-NMR (CDCl.sub.3) .delta. 166.4, 165.5, 145.6, 139.8, 131.0, 
130.2, 128.4, 128.2, 118.5, 118.2, 117.3, 18.1; MS (CI) 350 (100), 348 
(92), 268 (29), 131 (91), 104 (25), 77 (29). 
Schiff Base 6e (R.sup.1 =4-NO.sub.2, R.sup.2 =2,6-Cl-4-CF.sub.3 C.sub.6 
H.sub.2): 
5-Nitrosalicylaldehyde (1.30 g, 8.0 mmol), 
4-animo-3,5-dichlorobenzotrifluoride (1.80 g, 8.0 mmol) and ethanol (25 
mL) afforded 2.70 g (90%) of the title compound as a yellow solid. mp. 
173-174.degree. C.; .sup.1 H-NMR (CDCl.sub.3).delta. 12.96 (s, 1H), 8.68 
(s, 1H), 8.43 (d, J=2.7 Hz, 1H), 8.36 (dd, J=9.3, 2.7 Hz, 1H), 7.70 (s, 
2H), 7.17 (d, J=9.3 Hz, 1H); .sup.13 C-NMR (CDCl.sub.3) .delta. 168.7, 
166.1, 145.7, 140.1, 129.4, 129.1, 127.6, 125.8, 125.7, 118.5, 116.9; HRMS 
(CI) calcd for C.sub.14 H.sub.11 N.sub.2 O.sub.3 F.sub.3 Cl.sub.2 
[M+H].sup.+ 378.9864, found 378.9866. 
Schiff Base 6f (R.sup.1 =6-Me-4-NO.sub.2, R.sup.2 =2,6-i-PrC.sub.6 
H.sub.3): 
3-Methyl-5-nitrosalicylaldehyde (0.63 g, 3.40 mmol), 2,6-diisopropylaniline 
(0.80 g, 3.40 mmol) and ethanol (20 mL) afforded 1.10 g (95%) of the title 
compound as a yellow solid. mp. 120-121.degree. C.; .sup.1 H-NMR 
(CDCCl.sub.3) .delta. 14.50 (s, 1H), 8.38 (s, 1H), 8.21 (s, 1H), 7.23 (s, 
4H), 2.95 (septet, J=6.9 Hz, 2H), 2.42 (s, 3H), 1.20 (d, J=6.9 Hz, 12H); 
.sup.13 C-NMR (CDCl.sub.3) .delta. 165.4, 144.4, 139.1, 138.5, 132.9, 
128.5, 128.2, 126.0,125.9, 123.2, 116.3, 28.0, 23.3, 15.4; HRMS (DCI) 
C.sub.20 H.sub.25 N.sub.2 O.sub.3 [M+H].sup.+ 341.1865, found 341.1873. 
Schiff Base 6g (R.sup.1 =4-NO.sub.2, R.sup.2 =2,6-i-Pr-4-NO.sub.2 -C.sub.6 
H.sub.2): 
5-Nitrosalicylaldehyde (1.0 g, 6.0 mmol), 2,6-diisopropyl-4-nitroaniline 
(1.30 g, 6.0 mmol) and ethanol (20 mL) afforded 2.0 g (91%) of the title 
compound as a yellow solid. mp. 118-120.degree. C.; .sup.1 H-NMR 
(CDCl.sub.3) .delta. 13.34 (s, 1H), 8.43 (s, 2H), 8.33 (dd, J=9.0, 2.4 Hz, 
1H), 8.09 (s, 2H), 7.18 (d, J=9.0 Hz, 1H), 3.00 (septet, J=6.9 Hz, 2H), 
1.23 (d, J=6.9 Hz, 12H); .sup.13 C-NMR (CDCl.sub.3) .delta. 166.0, 165.7, 
150.3, 145.8, 140.3, 134.0, 128.8, 128.6, 118.9, 118.1, 117.1, 28.3, 22.6; 
HRMS (DCI) C.sub.19 H.sub.22 N.sub.3 O.sub.5 [M+H].sup.+ 372.1559, found 
372.1560. 
Schiff Base 6h (R.sup.1 =4-NO.sub.2, R.sup.2 =1-adamantanemethyl): 
5-Nitrosalicylaldehyde (0.84 g, 5.0 mmol), 1-adamantanemethylaniline (0.90 
g, 5.0 mmol) and ethanol (15 mL) afforded 1.40 g (92%) of the title 
compound as a yellow solid. mp. 178-180.degree. C.; .sup.1 H-NMR 
(CDCl.sub.3) .delta. 15.18 (s, 1H), 8.21 (s, 1H), 8.16 (t, J=9.0 Hz, 2H), 
6.86 (d, J=9.3 Hz, 1H), 3.29 (s, 2H), 2.00 (s, 3H), 1.65 (m, 6H), 1.55 
(bs, 6H); .sup.13 C-NMR (CDCl.sub.3) 172.9, 164.4, 137.2, 129.1, 128.5, 
120.4, 115.1, 68.4, 40.1, 33.9, 27.9; HRMS (DCI) C.sub.18 H.sub.23 N.sub.2 
O.sub.3 [M+ H].sup.+ 315.1709, found 315.1710. 
General Procedure for the Preparation of Thallium Salts (7a-h). 
To a solution of the appropriate Schiff base (6a-h) in benzene or THF (10 
mL), a solution of thallium ethoxide in benzene or THF (5 mL) was added 
dropwise at room temperature. Using a glass pipette, the solution of 
thallium ethoxide in benzene or THF was filtered through a plug of 
glasswool to remove any impurities. Immediately after the addition, a pale 
yellow solid formed and the reaction mixture was stirred for 2 hour at 
room temperature. Filtration of the solid under a nitrogen or argon 
atmosphere gave the respective thallium salt (7a-h) in quantitative yield. 
The salt was immediately used in the next step without further 
purification. 
General Procedure for the Preparation of Schiff Base Substituted Ruthenium 
Complexes (8a-h). 
A solution of the appropriate thallium salt (7a-h) in THF (5 mL) was added 
to a solution of ruthenium complex 3 in THF (5 mL). The reaction mixture 
was 5 stirred at room temperature for 3 hours. After evaporation of the 
solvent, the residue was dissolved in a minimal amount of benzene and 
cooled to 0.degree. C. The thallium chloride (the byproduct of the 
reaction) was removed via filtration. The desired complex was then washed 
with cold benzene (10 mL.times.3) and the filtrate was evaporated. The 
solid residue was recrystallized from pentane (-70.degree. C.) to give the 
respective Schiff base substituted ruthenium complex (8a-h) in moderate to 
good yield as a brown solid. Any modifications are described below for 
each reaction. 
Ruthenium Schiff Base Complex 8a: 
Ruthenium complex 3 (1.20 g, 1.50 mmol), thallium salt 7a (0.78 g, 1.60 
mmol), and THF (20 mL) afforded 0.89 g (75%) of the title complex as a 
brown solid. mp. 119-122.degree. C.; .sup.1 H-NMR (CD.sub.2 Cl.sub.2) 
.delta. 19.68 (d, J=3.6 Hz, 1H), 8.06 (d, J=5.4 Hz, 1H), 7.92 (d, J=7.5 
Hz, 2H), 7.53 (t, J=7.2 Hz, 1H), 7.33-7.00 (m, 8H), 6.60 (t, J=7.2 Hz, 
1H), 3.36 (septet, J=6.9 Hz, 1H), 2.51 (q, J=11.7 Hz, 3H), 2.13 (septet, 
J=6.9 Hz, 1H), 1.79-1.52 (m, 20H), 1.38 (d, J=6.6 Hz, 3H), 1.22 (m, 10H), 
1.11 (d, J=6.9 Hz, 3H), 0.75 (dd, J=21.3, 6.9 Hz, 6H); .sup.31 P-NMR 
(CD.sub.2 Cl.sub.2) .delta. 6 52.23; MS (FAB) 787 (3), 386 (12), 315 (26), 
297 (19), 281 (49), 279 (19), 255 (8), 231 (20), 154 (23), 119 (23), 
Ruthenium Schiff Base Complex 8b: 
Ruthenium complex 3 (1.65 g, 2.0 mmol), thallium salt 7b (1.10 g, 2.10 
mmol), and THF (40 mL) afforded 1.40 g (82%) of the title complex as a 
brown solid. mp. 140-145.degree. C.; .sup.1 H-NMR (CD.sub.2 Cl.sub.2) 
.delta. 19.77 (d, J=3.3 Hz, 1H), 8.27 (d, J=2.7 Hz, 1H), 8.14 (d, J=5.4 
Hz, 1H), 8.10 (dd, J=9.6, 2.7 Hz, 1H), 7.94 (d, J=7.8 Hz, 2H), 7.60 (t, 
J=7.2 Hz, 1H), 7.30 (t, J=7.8 Hz, 2H), 7.21 (m, 2H) 7.09 (dd, J=6.9, 1.8 
Hz, 1H), 6.99 (d, J=9.3 Hz, 1H), 3.26 (septet, J=6.6 Hz, 1H), 2.52 (q, 
J=11.5 Hz, 3H), 2.11 (septet, J=6.6 Hz, 1H), 1.73 (bs, 20H), 1.40 (d, 
J=6.6 Hz, 3H), 1.23 (m, 10H), 1.15 (d, J=6.9 Hz, 3H), 0.78 (dd, J=17.4, 
6.9 Hz, 6H); .sup.31 P-NMR (CD.sub.2 Cl.sub.2) .delta. 52.23; HRMS (FAB) 
C.sub.44 H.sub.60 ClN.sub.2 O.sub.3 PRu [M].sup.+ 832.3074, found 
832.3104. 
Ruthenium Schiff Base Complex 8c: 
Ruthenium complex 3 (0.25 g, 0.30 mmol), thallium salt 7c (0.16 g, 0.32 
mmol), and THF (3 mL) afforded 0.13 g (54%) of the title complex as a 
brown solid. mp. 139-142.degree. C.; .sup.1 H-NMR (CD.sub.2 Cl.sub.2) 
.delta. 19.49 (d, J=4.7 Hz, 1H), 8.22 (d, J=2.8 Hz, 1H), 8.08 8.04 (m, 
3H), 7.98 (d, J=7.8 Hz, 2H), 7.56 (d, J=7.4 Hz, 1H), 7.35 (d, J=1.3 Hz, 
1H), 7.27 (t, J=7.5 Hz, 2H), 7.00 (d, J=9.6 Hz, 1H), 3.79 (s, 3H), 2.38 
(s, 6H), 1.75-1.21 (m, 30H); .sup.31 P-NMR (CD.sub.2 Cl.sub.2) .delta. 6 
50.51; HRMS (FAB) C.sub.41 H.sub.54 ClN.sub.2 O.sub.4 PRu [M].sup.+ 
806.2553, found 806.2520. 
Ruthenium Schiff Base Complex 8d: 
Ruthenium complex 3 (0.41 g, 0.50 mmol), thallium salt 7d (0.32 g, 0.55 
mmol), and THF (25 mL) afforded 0.35 g (80%) of the title complex as a 
brown solid. mp. 128-131.degree. C.; .sup.1 H-NMR (CD.sub.2 Cl.sub.2) 
.delta. 19.48 (d, J=4.8 Hz, 1H), 8.22 (d, J=2.7 Hz, 1H), 8.07 (dd, J=9.3, 
2.7 Hz, 1H), 8.03 (d, J=5.7 Hz, 1H), 7.98 (d, J=7.8 Hz, 2H), 7.58 (t, 
J=7.8 Hz, 1H), 7.28 (t, J=7.8 Hz, 2H), 7.17 (s, 1H), 7.00 (d, J=9.6 Hz, 
1H), 2.47 (q, J=12.0 Hz, 3H), 2.37 (s, 3H), 1.78-1.63 (bs, 20H), 1.50 (d, 
J=13.5 Hz, 3H), 1.30-1.16 (m, 10H); .sup.31 P-NMR (CD.sub.2 Cl.sub.2) 
.delta. 50.62; HRMS (FAB) C.sub.40 H.sub.51 BrClN.sub.2 O.sub.3 PRu 
[M].sup.+ 856.1532, found 856.1573. 
Ruthenium Schiff Base Complex 8e: 
Ruthenium complex 3 (0.34 g, 0.40 mmol), thallium salt 7e (0.26 g, 0.44 
mmol), and THF (20 mL) afforded 0.30 g (85%) of the title complex as a 
brown solid. mp. 145-149.degree. C.; .sup.1 H-NMR (CD.sub.2 Cl.sub.2) 
.delta. 19.39 (d, J=4.5 Hz, 1H), 8.25 (d, J=2.7 Hz, 1H), 8.09 (dd, J=9.3, 
2.7 Hz, 1H), 7.99 (m, 3H), 7.69 (d, J=18.0 Hz, 1H), 7.57 (t, J=7.2 Hz, 
1H), 7.35 (s, 1H), 7.28 (t, J=7.8 Hz, 1H), 7.02 (d, j=9.6 Hz, 1H), 2.48 
(q, J=11.7 Hz, 3H), 1.73-1.54 (m, 15H), 1.39 (m, 5H), 1.22 (bs, 10H); 
.sup.31 P-NMR (CD.sub.2 Cl.sub.2) .delta. 50.65; HRMS (FAB) C.sub.39 
H.sub.45 Cl.sub.3 F.sub.3 N.sub.2 O.sub.3 PRu [M].sup.+ 886.1199, found 
886.1179. 
Ruthenium Schiff Base Complex 8f: 
Ruthenium complex 3 (0.82 g, 1.0 mmol), thallium salt 7f (0.60 g, 1.10 
mmol), and THF (35 mL) afforded 0.68 g (80%) of the title complex as a 
brown solid. mp. 155-158.degree. C.; .sup.1 H-NMR (CD.sub.2 Cl.sub.2) 
.delta. 19.69 (d, J=2.7 Hz, 1H), 8.11 (d, J=4.5 Hz, 2H), 7.89 (d, J=7.8 
Hz, 1H), 7.55 (t, J=7.2 Hz, 1H), 7.33 (s, 1H), 7.24 (t, J=7.5 Hz, 2H), 
7.17 (m, 3H), 7.07 (d, J=7.2 Hz, 1H), 3.22 (septet, J=6.6 Hz, 1H), 2.58 
(q, J=11.4 Hz, 3H), 2.38 (s, 3H), 1.91 (septet, J=6.6 Hz, 1H), 1.80-1.54 
(m, 20H), 1.36 (d, J=6.6 Hz, 3H), 1.19 (bs, 13H), 1.10 (d, J=6.6 Hz, 3H), 
0.85 (d, J=6.9 Hz, 3H), 0.72 (d, J=6.3 Hz, 3H); .sup.31 P-NMR (CD.sub.2 
Cl.sub.2) .delta. 53.50; HRMS (FAB) C.sub.45 H.sub.62 ClN.sub.2 O.sub.3 
PRu [M].sup.+ 846.3230, found 846.3279. 
Ruthenium Schiff Base Complex 8g: 
Ruthenium complex 3 (0.66 g, 0.80 mmol), thallium salt 7g (0.51 g, 0.88 
mmol), and THF (50 mL) afforded 0.59 g (67%) of the title complex as a 
brown solid. mp. 160-163.degree. C.; .sup.1 H-NMR (CD.sub.2 Cl.sub.2) 
.delta. 19.72 (d, J=3.3 Hz, 1H), 8.30 (d, J=2.7 Hz, 1H), 8.13 (d, J=3.0 
Hz, 1H), 8.10 (s, 2H), 8.05 (d, J=2.1 Hz, 1H), 7.95 (d, J=2.4 Hz, 1H), 
7.92 (d, J=7.8 Hz, 2H), 7.61 (t, J=7.2 Hz, 1H), 7.30 (t, J=7.8 Hz, 2H), 
7.00 (d, J=9.6 Hz, 1H), 3.29 (septet, J=6.6 Hz, 1H), 2.48 (q, J=11.4 Hz, 
2H), 2.18 (septet, J=6.6 Hz, 1H), 1.72 (bs, 20H), 1.45 (d, J=6.9 Hz, 3H), 
1.20 (m, 13H), 0.80 (dd, J=21.0, 6.6 Hz, 6H); .sup.31 P-NMR (CD.sub.2 
Cl.sub.2) .delta. 52.54; HRMS (FAB) C.sub.44 H.sub.59 ClN.sub.3 O.sub.5 
PRu [M].sup.+ 877.2924, found 877.2887. 
Ruthenium Schiff Base Complex 8h: 
Ruthenium complex 3 (0.33 g, 0.40 mmol), thallium salt 7h (0.23 g, 0.44 
mmol), and THF (20 mL) afforded 0.18 g (54%) of the title complex as a 
brown solid. mp. 162-166.degree. C.; .sup.1 H-NMR (CD.sub.2 Cl.sub.2) 
.delta. 18.68 (d, J=13.5 Hz, 1H), 7.95 (dd, J=9.3 Hz, 1H), 7.89 (d, J=7.5 
Hz, 2H), 7.79 (d, J=3.0 Hz, 1H), 7.64(t, j=7.5 Hz, 1H), 7.38 (d, J=7.5 Hz, 
1H), 7.30 (t, J=7.8 Hz, 1H), 6.97 (d, J=9.3 Hz, 1H), 6.09 (d, J=10.8 Hz, 
1H), 3.00 (dd, J=10.8, 2.7 Hz, 2H), 2.29 (q, J=11.4 Hz, 3H), 1.99 (bs, 
3H), 1.84 (bs, 3H), 1.73 (m, 20H), 1.57 (m, 10H), 1.25 (d, J=8.7 Hz, 9H); 
.sup.31 P-NMR (CD.sub.2 Cl.sub.2) 38.95; HRMS (FAB) C.sub.43 H.sub.60 
ClN.sub.2 O.sub.3 PRu [M].sup.+ 820.3074, found 820.3079. 
General Procedure for the Ring-Closing Metathesis of Diethyl 
Diallylmalonate using Ruthenium Schiff Base Catalysts 8a-h. 
All reactions were performed on the benchtop in air by weighing 8 mol % of 
the respective catalyst (8a-h) into a dry NMR tube and dissolving the 
solid in 0.5 ml of CD.sub.2 Cl.sub.2 or C.sub.6 D.sub.6. A solution of 
diethyl diallylmalonate (0.1 mmol) in CD.sub.2 Cl.sub.2 or C.sub.6 D.sub.6 
(0.5 mL) was added. The tube was then capped, wrapped with parafilm, and 
shaken periodically. The studies were ran at both ambient temperatures and 
higher temperatures (.about.65.degree. C.) to access the activity and 
stability of the catalysts during the course of the reactions. Product 
formation and diene disappearance were monitored by integrating the 
allylic methylene peaks. 
X-ray Structure of the Ruthenium Complex 8b. 
Crystals suitable for X-ray structure determination were grown from a 
solution of isopropyl ether at -20.degree. C. over a few days. The brown 
crystal used for data collection was 0.10 mm.times.0.13 mm.times.0.44 mm. 
Data collection was carried out at 160 K. A total of 17106 reflections 
were collected, 7741 of which were independent. Data collection parameters 
are summarized in part by the Table 2. The structure was solved by direct 
methods using the Siemens SHELXS-86 program. The molecule was refined 
isotropically (with riding H atoms on dichloromethane solvent) with a 
fractional population parameter for each solvent molecule also refined. 
The hydrogen atoms were originally placed at calculated positions. 
Eventually, the coordinates of all but two (H38a and H38b) were refined, 
with Uiso's fixed at 1.2 times the Ueq of the attached atom. Refinement 
was full-matrix least-squares using SHELXL-93. 
Decomposition Experiment with Ruthenium Complexes 3 and 8b. 
Two NMR tube samples were prepared in toluene-d8, one containing 4.0 mmolar 
of 8b and the other containing 4.2 mmolar of 3, with an internal standard 
of anthracene. The samples were analyzed by .sup.1 H-NMR and placed in an 
85.degree. C. oil bath. After 30 minutes, the samples were again analyzed 
and replaced into the oil bath. After another 30 minutes, a final analysis 
by NMR was performed. For eacy analysis, the intensity of the carbene 
signal in the NMR was determined relative to the anthracene signal and 
used to calculate the molar concentration of the respective remaining 
carbene catalyst.