Optically active transition metal complexes. 130. Synthesis, crystal structures, and catalytic properties of chiral-at-metal (η6-arene)ruthenium(II) and (η6-arene)osmium(II) half-sandwich complexes. crystallization of pure diastereomers versus diastereomer mixture in a 1:1 ratio

Article abstract of DOI:10.1021/om020964u

Condensation of a number of optically active amines and α-amino acid esters with salicylaldehyde gave the chiral compounds HLL*1-HLL*-8. A series of diastereomeric complexes of the type (R_M,S_C)- and (S_M,S_C)-[(η⁶-arene)M(LL*)X] (1-14: M = Ru, Os; X = Cl, I), differing only in the metal configuration, were formed by reaction of [(η⁶-arene)MCl₂]₂ with these compounds in the presence of base and by halogen exchange. Five of the complexes were characterized by X-ray structure analyses. Three cases showed the structural peculiarity that the single crystals contained the R_M,S_C and S_M,S_C diastereomers with opposite configurations at the metal centers in a 1:1 ratio, whereas two cases crystallized as pure R_M,S_C diastereomers. Two complexes, the ligands of which (the salicylaldiminates of methyl phenylalaninate and methyl phenylglycinate) had racemized during the synthesis, crystallized as racemates R_Ru,S_C/S_Ru,R_C. Complexes 1-14 were tested as catalysts in the enantioselective isomerization of 2-n-butyl-4,7-dihydro-1,3-dioxepin to give 2-n-butyl-4,5-dihydro-1,3-dioxepin. Enantioselectivities up to 64% ee were achieved.

Full text of DOI:10.1021/om020964u

Organometallics 2003, 22, 1741-1750
1741
Op tica lly Active Tr a n sition Meta l Com p lexes. 130.1
Syn th esis, Cr ysta l Str u ctu r es, a n d Ca ta lytic P r op er ties
of Ch ir a l-a t-Meta l (η6-Ar en e)r u th en iu m (II) a n d
(η6-Ar en e)osm iu m (II) Ha lf-Sa n d w ich Com p lexes.
Cr ysta lliza tion of P u r e Dia ster eom er s ver su s
Dia ster eom er Mixtu r es in a 1:1 Ra tio
Henri Brunner,* Thomas Zwack, and Manfred Zabel†
Institut fu¨r Anorganische Chemie, Universita¨t Regensburg, D-93040 Regensburg, Germany
Wolfgang Beck and Andreas Bo¨hm
Department Chemie, Ludwig-Maximilians-Universita¨t, Butenandtstrasse 5-13,
D-81377 Mu¨nchen, Germany
Received November 22, 2002
Condensation of a number of optically active amines and R-amino acid esters with
salicylaldehyde gave the chiral compounds HLL*-1-HLL*-8. A series of diastereomeric
complexes of the type (RM,SC)- and (SM,SC)-[(η6-arene)M(LL*)X] (1-14: M ) Ru, Os; X )
Cl, I), differing only in the metal configuration, were formed by reaction of [(η6-arene)MCl2]2
with these compounds in the presence of base and by halogen exchange. Five of the complexes
were characterized by X-ray structure analyses. Three cases showed the structural peculiarity
that the single crystals contained the RM,SC and SM,SC diastereomers with opposite
configurations at the metal centers in a 1:1 ratio, whereas two cases crystallized as pure
RM,SC diastereomers. Two complexes, the ligands of which (the salicylaldiminates of methyl
phenylalaninate and methyl phenylglycinate) had racemized during the synthesis, crystal-
lized as racemates RRu,SC/SRu,RC. Complexes 1-14 were tested as catalysts in the enanti-
oselective isomerization of 2-n-butyl-4,7-dihydro-1,3-dioxepin to give 2-n-butyl-4,5-dihydro-
1,3-dioxepin. Enantioselectivities up to 64% ee were achieved.
In tr od u ction
amino acid chelates,7,8 and much fewer studies on
analogous chiral-at-metal (η6-arene)osmium compounds.
The catalytic potential of ruthenium complexes in
organic synthesis is well documented.2 Frequently, half-
sandwich (η6-arene)ruthenium(II) complexes have been
used as precatalysts.3 In such half-sandwich complexes
of the three-legged piano-stool type, which contain the
unsymmetrical chelate ligand LL′ and another ligand
X, e.g. a halide, the metal atom is a chiral center. Using
an enantiomerically pure ligand LL*, e.g. of SC config-
uration, the two diastereomers RM,SC and SM,SC arise.4-6
Many studies on chiral-at-metal ruthenium compounds
of the type [(η6-arene)Ru(LL*)L] and [(η6-arene)Ru-
(LL*)L]X (arene ) benzene, mesitylene, hexamethyl-
benzene, p-cymene, LL* ) anionic or neutral enantio-
merically pure chelate ligand, L ) monodentate ligand
or halide, X ) anion) have been reported, including
In the present paper we describe the synthesis and
characterization as well as kinetic studies on the stabil-
ity of the metal configuration of ruthenium(II) and
osmium(II) half-sandwich complexes.9 The main focus
will be on two points: (i) their use in the enantioselec-
tive catalytic desymmetrization of 2-n-butyl-4,7-dihydro-
l,3-dioxepin and (ii) the crystallization of the diastere-
omer mixtures. Concerning the second point, in the vast
majority of cases single crystals obtained from the
solution of a mixture of diastereomers contain only one
diastereomer. This, actually, is the basis for the resolu-
tion of racemates by diastereomer separation via crys-
tallization. There are, however, a few examples known
with two diastereomers of the same ligand configuration
and opposite metal configuration present in the same
single crystal.10-20 In the present study three of the new
* To whom correspondence should be addressed. Fax: +49-941-
9434439. E-mail: henri.brunner@chemie.uni-regensburg.de.
† X-ray structure analyses.
(1) Part 129: Brunner, H.; Klankermayer, J .; Zabel, M. Organome-
tallics 2002, 21, 5746.
(2) Naota, T.; Takaya, H.; Murahashi, S.-I. Chem. Rev. 1998, 98,
2599.
(3) Noyori, R.; Hashiguchi, S. Acc. Chem. Res. 1997, 30, 97.
(4) Brunner, H. Adv. Organomet. Chem. 1980, 18, 151.
(5) Brunner, H. Angew. Chem. 1999, 111, 1248; Angew. Chem., Int.
Ed. 1999, 38, 1194.
(7) Severin, K.; Bergs, R.; Beck, W. Angew. Chem. 1998, 110, 1722;
Angew. Chem., Int. Ed. 1998, 37, 1635.
(8) Carmona, D.; Lamata, M. P.; Oro, L. A. Eur. J . Inorg. Chem.
2002, 2239.
(9) Zwack, T., Ph.D. Thesis, Universita¨t Regensburg, 2001.
(10) Kra¨mer, R.; Polborn, K.; Wanjek, H.; Zahn, I.; Beck, W. Chem.
Ber. 1990, 123, 767; Kra¨mer, R.; Maurus, M.; Polborn, K.; Su¨nkel, K.;
Robl, C.; Beck, W. Chem. Eur. J . 1996, 2, 1518.
(11) Carmona, D.; Mendoza, A.; Lahoz, F. J .; Oro, L. A.; Lamata,
M. P.; San J ose´, E. J . Organomet. Chem. 1990, 396, C17.
(6) Brunner, H. Eur. J . Inorg. Chem. 2001, 905.
10.1021/om020964u CCC: $25.00 © 2003 American Chemical Society
Publication on Web 03/21/2003

1742 Organometallics, Vol. 22, No. 8, 2003
Sch em e 1. Syn th esis of th e Op tica lly Active Sa licyla ld im in a tes HLL*-1-HLL*-8
Brunner et al.
complexes showed the structural peculiarity of a 1:1
diastereomer crystallization including a ruthenium
complex, the corresponding intimately related osmium
compound of which did not show 1:1 diastereomer
crystallization but crystallization as a pure diastereomer
in two different modifications, indicating a delicate
balance between the 1:1 diastereomer crystallization
and the crystallization as a pure diastereomer. This
alternative, of fundamental importance for optical reso-
lutions by diastereomer separation via crystallization,
will be analyzed.
methylene chloride and deprotonated using KOtBu.
After the suspension was cooled to -78 °C, [(η6-arene)-
MCl2]2 (arene ) benzene, mesitylene, hexamethylben-
zene, p-cymene; M ) Ru, Os) was added (Schemes 2 and
3). Complexes 112,23 and 924,25 were known. Complex 14
was formed by halogen exchange using complex 5 and
an excess of sodium iodide in methanol.
All the complexes 1-14 contained enantiomerically
pure S-configured ligands, except complexes 7 and 8,
the ligands of which had completely racemized during
complex formation. Thus, in solution all the complexes
consisted of the two diastereomers RM,SC and SM,SC,
differing only in the metal configuration, except com-
plexes 7 and 8, for which two diastereomeric pairs of
enantiomers, RM,SC/SM,RC and SM,SC/RM,RC, were
presentsa stereochemical situation similar but not
identical with the two diastereomers RM,SC and SM,SC.
Dia st er eom er E q u ilib r ia a n d E p im er iza t ion
Stu d ies. For all the complexes 1-14 the diastereomers
RM,SC and SM,SC, which only differ in the configuration
Resu lts a n d Discu ssion
Syn th eses. Compounds HLL*-1-HLL*-8 were pre-
pared by condensation of salicyaldehyde with the ap-
propriate chiral amines or amino acid esters in metha-
nol by gentle heating. HLL*-1-HLL*4 were condensa-
tion products of commercially available chiral amines
and salicylaldehyde. HLL*-5-HLL*-8 were Schiff bases
of salicylaldehyde and R-amino acid esters. The synthe-
sis of the optically active salicylaldiminates is shown
in Scheme 1. As the amino acid derived compounds
HLL*-5-HLL*-8 could have racemized during the
1
at the metal center, exhibited different H NMR spectra.
Thus, the diastereomer ratio could be determined by
integration of suitable signals. In the majority of the
present (η6-arene)ruthenium and (η6-arene)osmium com-
plexes the signals of the η6-arene ligand of the major
diastereomer showed a high-field shift compared to
those of the minor diastereomer. Such a behavior also
had been observed for other half-sandwich complexes
subject to the “â-phenyl effect”.26 This â-phenyl effect
is an attractive C-H/π-interaction27 present only in the
major diastereomers. It arises because, by rotation
about the N-C* and C*-Cipso bonds of the 1-phenyl-
ethyl group, the phenyl substituent moves as close to
the π-bonded arene ligand as possible (T-shaped ar-
rangement of the phenyl and the arene ligand). Due to
this face-on orientation, the arene ligand lies in the
magnetic anisotropy cone of the phenyl ring of the
1
synthesis,21 they were examined by H NMR spectros-
copy with (S)-(+)-1-(9-anthryl)-2,2,2-trifluoroethanol.
HLL*-5 turned out to be enantiomerically pure even
when strong bases had been used. However, the phenyl-
alanine derivative HLL*-7 could be obtained enantio-
merically pure only with weak bases such as NaHCO3.
HLL*-8 was isolated with 60% ee under conditions for
which no racemization had been reported.22
For the synthesis of diastereomeric ruthenium and
osmium complexes 1-14, the ligands were dissolved in
(12) Mandal, S. K.; Chakravarty, A. R. J . Chem. Soc., Dalton Trans.
1992, 1627.
(13) Mandal, S. K.; Chakravarty, A. R. Inorg. Chem. 1993, 32, 3851.
(14) Carter, L. C.; Davies, D. L.; Duffy, K. T.; Fawcett, J .; Russel,
D. R. Acta Crystallogr., Sect. C 1994, 50, 1559.
(15) Attar, S.; Catalano, V. J .; Nelson, J . H. Organometallics 1996,
15, 2932.
(22) Fuhrhop, J .; Penzlin, G. Organic Synthesis, 2nd ed.; VCH:
Weinheim, Germany, 1994; p 232.
(16) Brunner, H.; Neuhierl, T.; Nuber, B. Eur. J . Inorg. Chem. 1998,
1877.
(17) Faller, J . W.; Liu, X.; Parr, J . Chirality 2000, 12, 325.
(18) Rath, R. K.; Nethanji, M.; Chakravarty, A. R. Polyhedron 2002,
21, 1929.
(19) Brunner, H.; Weber, M.; Zabel, M. Synthesis, in press.
(20) Brunner, H.; Dormeier, S.; Zabel, M. Eur. J . Inorg. Chem. 2002,
2594.
(21) Grigg, R.; Gunaratne, H. Q. N. Tetrahedron Lett. 1983, 24, 4457
and literature cited therein.
(23) Mandal, S. K.; Chakravarty, A. R. J . Organomet. Chem. 1991,
417, C59.
(24) Brunner, H.; Oeschey, R.; Nuber, B. Angew. Chem. 1994, 106,
941; Angew. Chem., Int. Ed. Engl. 1994, 33, 866.
(25) Brunner, H.; Oeschey, R.; Nuber, B. J . Chem. Soc., Dalton
Trans. 1996, 1499.
(26) Brunner, H. Angew. Chem. 1983, 95, 921; Angew. Chem., Int.
Ed. Engl. 1983, 22, 897 and literature cited therein.
(27) Nishio, M.; Hirota, M.; Umezawa, Y. The CH/π Interaction;
Wiley-VCH: Weinheim, Germany, 1998.

Optically Active Transition Metal Complexes
Organometallics, Vol. 22, No. 8, 2003 1743
Sch em e 2. Syn th esis of th e Ha lf-Sa n d w ich Ru th en iu m (II) Com p lexes 1-12a
a
For 1-11 only the diastereomers with the RRu,SC configuration are shown; for 12 only the diastereomer with the SRu,SC
configuration is shown.
Sch em e 3. Syn th esis of th e Ha lf-Sa n d w ich Osm iu m (II) Com p lexes 13 a n d 14
a
Only the diastereomer with the ROs,SC configuration is shown.
1-phenylethyl substituent, which causes the high-field
shift. In the solid state this face-on orientation is found
in complexes 1,23 2, and 13 (see below).
intramolecular C-H/π-interaction was lacking, the
equilibrium diastereomer ratios dropped to unspectacu-
lar values around 50:50. Thus, the cyclohexyl ring of
ligand HLL*-3 in complex 3 did not interact with the
cymene ligand, the diastereomer ratio in CDCl3 being
54:46.
The equilibrium diastereomer ratios for the chloro-
and iodoruthenium complexes 5 and 12, in CDCl3
containing the valine methyl ester ligand, were 70:30;
for the osmium complex 14, the analogue of 5, it was
64:36. The ratio increased for the benzyl ester 6 and
the benzyl derivative 7 to 80:20. The rise of the dias-
tereomer excess to 84% de in complex 8 may be due to
a C-H/π-interaction.
In the solid state diastereomers such as those dis-
cussed here are configurationally stable at the metal
atom. In solution some of them prove to be stable; others
are labile with respect to the metal configuration.4-6
Knowledge of the configurational stability is important,
as the lability of the metal configuration has been
overlooked in a number of recent papers, resulting in
It is known that the â-phenyl effect persists in
solution.26 It is responsible for the high-field shift of the
signal of the major diastereomer compared to the minor
diastereomer, the signal of which appears at its normal
position. The â-phenyl effect also affects the diastere-
omer ratios at equilibrium, the major diastereomer
being favored by the attractive C-H/π-interaction with
respect to the minor diastereomer. For ruthenium
complex 1 the ratio in CDCl3 was RRu,SC:SRu,SC ) 85:
15,13,23 and for the osmium analogue it was 80:20. Going
from the phenyl to a naphthyl substituent in the
1-arylethyl group in the Ru series increased the dias-
tereomer ratio at equilibrium. Thus, for the 1-naphthyl
complex 2 only one diastereomer was observed, indicat-
ing a diastereomer ratio >99:1. The assignment of the
R
Ru,SC configuration to the dominating isomer was
supported by the high-field shift of the η6-p-cymene
signal in the 1H NMR spectrum. If the attractive

1744 Organometallics, Vol. 22, No. 8, 2003
Brunner et al.
misinterpretations and wrong conclusions.6,28 Low-tem-
1
perature H NMR is a convenient tool for studying the
configurational stability/lability at the metal atom.
(η6-Arene)ruthenium half-sandwich complexes of the
type 1-11 have been studied with respect to the
stability of the metal configuration in detailed kinetic
studies24,25,29 which showed that the epimerization is
already rapid at temperatures below room temperature.
Thus, solutions of ruthenium complexes 1-11, standing
for some time at room temperature, will contain the two
diastereomers RRu,SC and SRu,SC at their equilibrium
concentrations.
To investigate the configurational stability of the
corresponding osmium complexes, powdered crystals of
(ROs,SC)-14 were dissolved in CD2Cl2 at -60 °C, 1H
NMR mainly showing the signals of the major diaste-
reomer. The signals of the minor diastereomer were
visible, albeit in a much lower concentration than at
equilibrium. The presence of the signals of the minor
diastereomer may be due to the start of epimerization
during dissolution or, more probable, to the presence of
small amounts of the minor diastereomer in the solid
sample. Around -20 °C the signals of the minor dias-
tereomer grew until the diastereomer ratio had reached
the equilibrium ratio 65:35, indicating that the configu-
rational lability of the osmium compounds is similar to
that of the corresponding ruthenium complexes.
X-r a y Str u ctu r e An a lyses. In the present study we
carried out eight X-ray structure analyses using crystals
obtained from solutions of the various diastereomer
mixtures. From solutions of the two diastereomers
RM,SC and SM,SC in the three cases 5, 12, and 13,
unexpectedly, we found crystals which contained both
diastereomers RM,SC and SM,SC in a 1:1 ratio in the
same lattice. In the three cases 2 and 14 (two modifica-
tions of the latter species) we found the expected
crystallization of a pure diastereomer, here of the
favored RM,SC diastereomers. In the two cases 7 and 8
the ligands had racemized during the synthesis. There-
fore, in solution the enantiomers of each of the two
diastereomers RM,SC/SM,RC and SM,SC/RM,RC were
present. In these two cases the enantiomers of the major
diastereomer RRu,SC/SRu,RC crystallized.
1:1 diastereomer crystallization as encountered in the
cocrystallization of the diastereomers RM,SC and SM,SC
of 5, 12, and 13 is most unusual, because normally the
crystallization of a diastereomer mixture gives single
crystals of one diastereomer, usually the less soluble
diastereomer, which in fact is the basis for the resolution
of racemates by conversion into diastereomers and
separation via fractional crystallization.
The peculiar 1:1 cocrystallization of the two diaster-
eomers RM,SC and SM,SC in one single crystal, discussed
in a preliminary communication,30 compared to the
“normal” crystallization of one diastereomer (RM,SC),
has been analyzed for the intimately related compounds
5 and 14, differing only in the central metal Ru and Os,
respectively. In both compounds the asymmetric carbon
atom in the ligand has the expected SC configuration.
F igu r e 1. ORTEP plot of the molecular structure of
complexes (RRu,SC)-5 (right side) and (SRu,SC)-5 (left side)
in a 1:1 ratio within the same single crystal. Ellipsoids are
drawn at the 50% probability level. Hydrogen atoms have
been omitted for clarity.
Ta ble 1. Bon d Len gth s (Å) a n d An gles (d eg) in th e
1:1 La ttice of (RRu ,SC)-5 a n d (SRu ,SC)-5 a s Well a s in
th e Mon oclin ic a n d Or th or h om bic Mod ifica tion s of
(ROs,SC)-14
(ROs,SC)-14
(RRu,SC)- and
(SRu,SC)-5
monoclinic
mono-
clinic
ortho-
rhombic
Bond Lengths
M-Cy(centroid)
M-Cl
1.670-1.689
1.655
1.662
2.446(2)-2.423(2)
2.062(6)-2.053(6)
2.092(6)-2.120(6)
2.433(17) 2.4326(11)
2.077(5) 2.060(3)
2.101(5) 2.111(3)
M-O
M-N
Bond Angles
O-M-Cl
N-M-Cl
O-M-N
85.15(19)-84.43(18) 84.02(14) 83.47(10)
82.94(18)-85.17(17) 83.98(15) 84.13(10)
88.6(2)-88.8(2)
87.3(3)
87.03(13)
Dihedral Angle C(COOR)-C*-N-M
C42-C41-N2-Ru2 -83.6(6)a
C19-C18-N1-Rul -76.1(7)b
C2-C1-N-Os
-99.4(6)
a
b
RRu,SC diastereomer. SRu,SC diastereomer.
The metal configuration is assigned according to the
priority sequence Cy > Cl > O > N.31,32
Crystallization at 4 °C by diffusion of petroleum
ether into a toluene solution of the two diastereomers
(RRu,SC)- and (SRu,SC)-[(η6-p-cymene)Ru(LL*)Cl] of 5
afforded dark red single crystals which contained two
independent molecules in the ratio 1:1 in the unit cell.
In both molecules the chiral carbon atoms of the valine
ester groups had the expected SC configuration, whereas
ruthenium atom Ru1 had the RRu and ruthenium atom
Ru2 the SRu configuration. Thus, from a 70:30 mixture
in solution the two diastereomers RRu,SC and SRu,SC
crystallized in a 1:1 ratio in the same single crystal
(Figure 1).
In the 1:1 crystal of the two diastereomers of 5, the
bond lengths and bond angles of the two diastereomers
RRu,SC and SRu,SC are relatively similar (Table 1). In
the complex with SRu configuration the Ru-N and the
Ru-Cy(centroid) distances are a little shorter, whereas
the Ru-O and the Ru-Cl bonds are slightly longer than
in the isomer with RRu configuration. Furthermore, two
(28) Brunner, H.; Zwack, T. Organometallics 2000, 19, 2423.
(29) Brunner, H.; Oeschey, R.; Nuber, B. Inorg. Chem. 1995, 34,
3349.
(30) Brunner, H.; Weber, M.; Zwack, T.; Zabel, M. Submitted for
publication in Angew. Chem.
(31) Lecomte, C.; Dusausoy, Y.; Protas, J .; Tirouflet, J .; Dormond,
A. J . Organomet. Chem. 1974, 73, 67.
(32) Brunner, H. Enantiomer 1997, 2, 133.

Optically Active Transition Metal Complexes
Organometallics, Vol. 22, No. 8, 2003 1745
bond angles are smaller and one is larger, but only
slightly, emphasizing the similarity between the two
diastereomers. The ester substituent at the chiral
carbon atom in both cases is almost perpendicular to
the chelate plane (dihedral angles -83.6 and -76.1°).
In the SRu,SC isomer it orients toward the chloro ligand,
whereas in the RRu,SC isomer it points toward the
cymene ligand.
Figure 1 shows that the two diastereomers almost
form a “racemate”, connected by an “inversion center”.
In our analysis we place this inversion center exactly
halfway between Rul and Ru2. The deviations of the
four different substituents around the Ru atoms, Cy-
(centroid), Cl, O, and N, from inversion symmetry are
extremely small, ranging between 0.13 and 0.23 Å.
Similarly, the atoms in the ligand backbones and in the
cymene rings facing each other closely follow this
inversion symmetry with deviations below 0.2 Å. Natu-
rally, inconsistencies arise for the chiral nitrogen sub-
stituents, which for both diastereomers have the same
S configuration, excluding inversion symmetry.
F igu r e 2. ORTEP plot of the molecular structure of the
complex (ROs,SC)-14 (monoclinic modification). Ellipsoids
are drawn at the 50% probability level. Hydrogen atoms
have been omitted for clarity.
At 5.6420(9) Å the Ru-Ru distance in the “inversion
pair” is extremely short. All the other Ru-Ru distances
are longer than 8.6 Å. Thus, in these inversion pairs
two diastereomers assemble in the same way as two
enantiomers do in a racemate related by an inversion
center, forming a kind of supramolecular aggregate on
the basis of molecular recognition. In the center the
pairs of diastereomers RRu,SC and SRu,SC are image/
mirror image related; toward the outside of the pairs,
however, centrosymmetry is lost. The lattice is formed
by translation of these inversion pairs.
Os almost the same. Thus, some of the Os-ligand bonds
and ligand-Os-ligand angles are slightly shorter and
some are slightly longer than in the two ruthenium
diastereomers. Some are even intermediate between
those of the two ruthenium diastereomers.
In the crystal of (ROs,SC)-14 the ester substituent is
almost perpendicular to the chelate plane and oriented
toward the cymene ligand similar to the RRuSC diaste-
reomer. Given the extreme similarities between the
diastereomers (RRuSC)- and (SRu,SC)-5 and (ROs,SC)- and
(SOsSC)-14 it is surprising that the ruthenium complexes
crystallize as two diastereomers in a 1:1 ratio, while in
the osmium case a single diastereomer crystallizes, even
in two different modifications. This shows that there is
a delicate balance between the two situations: crystal-
lization as a pure diastereomer or crystallization as two
diastereomers in a 1:1 ratio. Taking into account on one
hand the similarity of the Ru and Os diastereomers 5
and 14 and on the other hand their different behaviors
on crystallization, the conclusion is that it will be
difficult to predict which of the two alternatives will be
realized in other cases.
In the 1:1 crystals of (RRu,SC)-5/(SRu,SC)-5 molecular
recognition occurs between two (Cy)Ru(Osal)Cl frag-
ments of opposite metal configuration, which approach
each other by inversion symmetry. With almost parallel
Ru-Cy centroids the fragments orient their Osal-Cl
edges toward one another, resulting in O1-Cl2 and O2-
Cl1 distances of 5.174 and 5.352 Å. There are 2 × 2
hydrogen bonds between the C-H groups of the cymene
rings and the Cl and Osal substituents of opposite
molecules (distances (angles) C3-H‚‚‚O2 ) 3.467 Å
(163.41°), C29-H‚‚‚O1 ) 3.307 Å (170.87°), C2-H‚‚‚Cl2
) 3.656 Å (143.93°), and C28-H‚‚‚Cl1 ) 3.742 Å
(141.15°)), which arrange the isopropyl and methyl
groups of the cymene rings such that together with the
chloro and the oxygen substituents they close a shell
around the inner core of the inversion pair.
In both modifications of 14 the diastereomer (ROs,SC)-
14 forms the lattice with the shortest Os-Os distance,
8.1771(6) Å. There are no metal-metal distances around
5.6 Å as in the 1:1 ruthenium “inversion pairs”. All the
Os-Os distances are in the range of the Ru-Ru
distances outside the “inversion pairs”.
Osmium complex 14, the analogue of ruthenium
complex 5, is also configurationally labile in solution.
The diastereomer ratio in CDCl3 at room temperature
is 64:36, similar to that for the corresponding ruthenium
complex. Diffusion of petroleum ether into a toluene
solution of 14 affords two different types of red crystals,
both suitable for X-ray analysis. Both contain only the
As for complex 5, 1:1 cocrystallization of the two
diastereomers RM,SC/SM,SC was also observed for the
iodoruthenium complex 12 and for the (S)-l-phenylethyl-
derived osmium complex 13. These cases were analyzed
similarly to those of the 1:1 crystal of complex 5. Thus,
the Ru-Ru distance of 5.8194(19) Å in the inversion
pair of the iodo complex was much smaller than the
outside-pair Ru-Ru distances, which only started at
7.4221(18) Å. The 1:1 diastereomer cocrystallization of
the Os complex 13 closely linked up with that of its Ru
R
Os,SC diastereomer in the monoclinic and orthorhombic
system, respectively. Thus, surprisingly, the osmium
compound 14 crystallizes as a pure diastereomer and
not as a 1:1 mixture of two diastereomers (Figure 2).
The relevant bond lengths and angles for both modifica-
tions are given in Table 1 (last two columns). They are
extremely similar to those of the two ruthenium dia-
stereomers. This is a consequence of the well-known
lanthanide contraction, which makes the radii of Ru and

1746 Organometallics, Vol. 22, No. 8, 2003
Brunner et al.
Ta ble 2. Cr ysta llogr a p h ic Da ta for Com p ou n d s 5, 12, a n d 13
5
12
13
empirical formula
fw
cryst syst
2 × C23H30ClNO3Ru
2 × 505.02
monoclinic
P21
2 × C25H28ClNOOs
2 × 584.16
monoclinic
P21
2 × C23H30ClNO3Ru
2 × 596.45
triclinic
P1
space group
Z
a (Å)
b (Å)
c (Å)
2
4
2
11.4964(10)
16.0597(9)
12/86028(11)
90
106.889(9)
90
2272.0(3)
1.476
0.831
10.9275(9)
16.8397(11)
12.79449(10)
90
110.506(9)
90
2205.2(3)
1.760
5.920
7.9952(7)
10.1954(12)
15.0628(14)
77.111(12)
86.246(11)
88.921(12)
1194.3(2)
1.659
R (deg)
â (deg)
γ (deg)
V (Å3)
Fcalcd (g cm-3
)
abs coeff (mm-1
F(000)
)
1.971
592
1040
1144
θ range (deg)
no. of rflns
Rint
2,24-25.86
1.99-25.77
2.05-25.87
31 852
31 086
9954
-0.0346
8673/523
1.113
0.0548/0.1378
0.0595/0.1407
3.429/-0.987
193233
0.0909
8373/523
1.061
0.0272/0.0649
0.0284/0.0652
2.057/-1.481
193238
0.0827
6061/293
1.069
0.0632/0.1840
0.0744/0.1913
0.993/-1.239
193232
no. of data/params
goodness of fit on F2
R1/wR2 (I > 2σ(I))
R1/wR2 (all data)
largest diff peak and hole (e Å-3
CCDC no.
)
Ta ble 3. Cr ysta llogr a p h ic Da ta for Com p ou n d s 2, 7, 8, a n d 14
14
2
7
8
empirical formula
fw
C
29H30ClNORu
C27H30ClNO3Ru
553.04
C26H28ClNO3Ru
539.01
C23H30ClNO3Os
594.16
C23H30ClNO3Os
594.16
545.86
cryst syst
space group
Z
orthorhombic
P212121
4
orthorhombic
Pbca
8
triclinic
P1h
2
monoclinic
P21
2
orthorhombic
P212121
4
a (Å)
b (Å)
c (Å)
11.1932(6)
12.3356(6)
38.174(2)
90
90
90
-5270.9(5)
1.482
0.82
2412
7.7043(3)
18.5592(7)
34.0149(19)
90
90
90
4863.6(4)
1.511
0.784
7.9845(9)
11.2624(11)
13.9219(15)
100.291(12)
103.497(12)
98.144(12)
1175.6(2)
1.523
9.3664(7)
15.8032(11)
9.0952(7)
90
123.299(8)
90
1125.23(18)
1.754
5.808
8.6386(5)
15.5224(11)
16.8700(11)
90
90
90
2262.1(3)
1.745
5.778
R (deg)
â (deg)
γ (deg)
V (Å3)
Fcalcd (g cm-3
)
abs coeff (mm-1
F(000)
)
0.808
552
2272
584
1168
θ range (deg)
no. of rflns
Rint
1.73-25.18
2.27-25.22
2.67-25.77
2.51-25.75
2.62-25.83
57 390
47 485
16 425
11 588
22 009
0.0507
0.0802
0.0741
0.0379
0.0826
no. of data/params
goodness of fit on F2
R1/wR2 (I > 2σ(I))
R1/wR2 (all data)
9259/622
1.012
0.0290/0.0676
0.0349/0.0699
0.827/-0.401
193231
4366/298
1.049
0.0361/0.0898
0.0463/0.0941
0.992/-0.811
193235
4180/289
0.999
0.0284/0.0694
0.0349/0.0713
0.971/-0.608
193234
4201/262
1.019
0.0245/0.0562
0.0284/0.0570
1.948/-1.110
193236
4338/262
1.043
0.0241/0.0568
0.0251/0.0570
1.668/-1.265
193237
largest diff peak and hole (e Å-3
CCDC no.
)
counterpart.12 The crystallographic data of 5, 12, and
13 are summarized in Table 2.
Complex 2 crystallized as the pure RRu,SC diastereo-
mer similar to compound 14. The 1-naphthyl substituent
showed a face-on orientation toward the cymene ligand
(see above). The crystallographic data of 2 and 14 are
summarized in Table 3 together with the corresponding
data for 7 and 8, the crystals of which contain the
enantiomers RRu,SC/SRu,RC of the major diastereomers
an expected behavior for the stereochemical situation
given. In the unit cell of crystals of 7 there are eight
molecules which subdivide into two mirror image re-
lated four-molecule groups.9
1:1 cocrystallization of two diastereomers in the same
lattice has been observed occasionally.20 Interestingly,
the phenomenon is frequently encountered in the crys-
tallization of chiral-at-metal (η6-arene)ruthenium com-
plexes of the three-legged piano-stool type from solutions
containing both diastereomers. The first examples were
reported in 199010,11 and 1992.12 Examples from other
groups14,15,17,18 and our own group16 followed. Three new
examples are part of the present paper, and another
example will be published elsewhere.19 Interestingly,
the basis for most of these 1:1 diastereomer cocrystal-
lizations is the molecular recognition motif found for
(RRu,SC)-5/(SRU,SC)-5, as discussed in ref 30. Of course,
many (η6-arene)ruthenium complexes also crystallize
“normally” as pure diastereomers from solutions con-
taining diastereomer mixtures, as do complexes 2 and
14.
1
The H NMR spectra of 1:1 crystals of 5, 12, and 13,
dissolved in CD2Cl2 at -80 °C, showed a ratio of the
two diastereomers of exactly 50:50, the composition of
the crystals. Similarly prepared solutions of 2, 7, 8, and
14, containing only one diastereomer or the enantiomers
of one diastereomer, exhibited only one set of signals.
When these solutions were warmed to room tempera-
ture, all the ratios changed to the corresponding equi-

Optically Active Transition Metal Complexes
Organometallics, Vol. 22, No. 8, 2003 1747
Ta ble 4. En a n tioselective Desym m etr iza tion of 2-n -Bu tyl-4,7-d ih yd r o-1,3-d ioxep in (A) a ccor d in g to
Sch em e 4
yield (%)
entry
catalyst
B
C
ee of B (%)
1
2
3
4
5
6
7
8
[(η6-p-cymene)Ru(LL*-1)Cl] (1)
[(η6-benzene)Ru(LL*-1)Cl] (9)
[(η6-mesitylene)Ru(LL*-1)Cl] (10)
[(η6-C6Me6)Ru(LL*-1)Cl] (11)
[(η6-p-cymene)Ru(LL*-2)Cl] (2)
[(η6-p-cymene)Ru(LL*-3)Cl] (3)
[(η6-p-cymene)Ru(LL*-4)Cl] (4)
[(η6-p-cymene)Ru(LL*-5)Cl] (5)
[(η6-p-cymene)Ru(LL*-5)I] (12)
[(η6-p-cymene)Ru(LL*-6)Cl] (6)
[(η6-p-cymene)Ru(LL*-7)Cl] (7)
[(η6-p-cymene)Ru(LL*-8)Cl] (8)
[(η6-p-cymene)Os(LL*-1)Cl] (13)
[(η6-p-cymene)Os(LL*-5)Cl] (14)
99.2, 99.1
31.2, 31.1
11.4, 10.8
1.0, 1.5
0.8, 0.9
14.1, 15.5
1.0, 1.1
0.5, 0.7
1.4, 1.0
2.5, 2.3
1.1, 1.3
1.7, 1.6
2.0, 2.3
1.6, 2.1
1.5, 1.2
2.7, 1.6
1.3, 0.6
0.9, 0.7
51.0, 50.7 (+)
4.3, 4.7 (+)
20.4, 19.6 (+)
3.3, 3.6 (+)
95.3, 94.3
97.4, 97.6
11.9, 15.6
98.2, 98.3
97.9, 97.7
98.3, 97.7
97.0, 97.0
63.0, 62.7
46.3, 46.4
75.2, 75.8
53.5, 52.3 (+)
55.7, 54.5 (+)
2.0, 3.1 (+)
64.3, 64.3 (-)
63.8, 59.9 (-)
48.6, 48.6 (-)
9
10
11
12
13
14
0.3, 0.1 (-)
0.2, 0.2 (-)
Sch em e 4. En a n tioselective Isom er iza tion of
To analyze the influence of the arene ligand, com-
plexes 1 and 9-11 were tested as catalysts. Quantita-
tive conversion under standard reaction conditions was
achieved only with complex 1, which had served as the
standard catalyst for the desymmetrization reaction
before (entry 1).39 Going from benzene via mesitylene
to hexamethylbenzene in complexes 9-11 made the
catalytic activity drop appreciably (entries 2-4). Whereas
complexes 9 and 11 gave only low enantioselectivities
of 3-5% ee, complex 10 afforded 20% ee, leaving the
standard system 1 with 51% ee unrivaled.
2-n -Bu tyl-4,7-d ih yd r o-1,3-d ioxep in (A)
The standard system 1 is derived from the com-
mercially available (S)-l-phenylethylamine. A compari-
son with complexes 2 and 3, derived from the amines
(S)-1-(1-naphthyl)ethylamine and (S)-1-cyclohexylethyl-
amine, commercially available as well, showed high
conversion with an improved selectivity (entries 5 and
6). The equilibrium diastereomer ratios had increased
from the phenyl derivative 1 (86:14) to the naphthyl
derivative 2 (>99:1) and dropped to the cyclohexyl
derivative 3 (54:46), showing that there is no parallelism
to the catalytic reaction of Scheme 4. The (S)-leucinol
derivative 4 (entry 7) gave low conversion, maybe
because of tridentate ligand binding through the ad-
ditional OH substituent and a disappointing enantiose-
lectivity.
The change to salicylaldiminate ligands derived from
amino acid esters, such as the (S)-valine methyl ester
derivative HLL*-5, brought an appreciable improve-
ment. In fact, complex 5 afforded enantioselectivities up
to 64.3% ee with 98% conversion (entry 8), the best
results ever obtained in the desymmetrization of 2-n-
butyl-4,7-dihydro-1,3-dioxepin (A) using (arene)ruthe-
nium half-sandwich complexes as catalysts. The iodo
complex 12 (entry 9) gave almost the same results as
the chloro complex 5, whereas the enantioselectivity
dropped for the valine benzyl ester derivative 6 (entry
10). Complexes 7 and 8, which contained racemized
ligands, showed very good to reasonable catalytic activi-
ties (98% and 63% conversion, respectively) but due to
their racemic ligands no enantioselectivity (entries 11
and 12).
librium concentrations of the diastereomers, as ad-
dressed in the previous paragraph.9
Ca ta lytic Stu d ies. Complexes 1-14 were used as
catalysts in the enantioselective double bond migration
in 2-n-butyl-4,7-dihydro-1,3-dioxepin (A) to give 2-n-
butyl-4,5-dihydro-1,3-dioxepin (B) (Scheme 4), which is
a precursor for the syntheses of natural products.33,35
This reaction had been introduced in 198636 and opti-
mized successively37,38 by Frauenrath et al. Recently,
very high enantioselectivities using diphosphane-modi-
fied NiHal2 complexes as catalysts were obtained.38
The standard reaction was carried out in a THF/
methanol (2:1) mixture in the ratio catalyst:NaBH4:
substrate ) 1:26:200 at room temperature (reaction time
24 h).39 Nitrogen was blown over the solution for 15 min
to remove the hydrogen, which was formed from NaBH4
and methanol. This reduced the amount of the hydro-
genation product C to normally 1-2.5% (Table 4). The
activity and stereoselectivity of (η6-arene)ruthenium
half-sandwich complexes 1-11 depended strongly on the
arene ligand, the chiral salicylaldiminate ligand, and
the metal atom. The results are shown in Table 4.
(33) Frauenrath, H.; Runsink, J .; Scharf, H.-D. Chem. Ber. 1982,
115, 2728.
(34) Frauenrath, H.; Philipps, T. Liebigs Ann. Chem. 1985, 1303.
(35) Frauenrath, H.; Philipps, T. Liebigs Ann. Chem. 1985, 1951.
(36) Frauenrath, H.; Philipps, T. Angew. Chem. 1986, 98, 261;
Angew. Chem., Int. Ed. Engl. 1986, 25, 274.
(37) Frauenrath, H.; Reim, S.; Wiesner, A. Tetrahedron: Asymmetry
1998, 9, 1103.
(38) Frauenrath, H.; Brethauer, D.; Reim, S.; Maurer, M.; Raabe,
G. Angew. Chem. 2001, 113, 176; Angew. Chem., Int. Ed. 2001, 40,
177.
The variation of the transition metal resulted in
another interesting result. In the above screening,
ligands HLL*-1 and HLL*-5 had given the best results
in ruthenium complexes. Using the same ligands in the
corresponding osmium complexes, the catalytic activity
decreased and, surprisingly, the enantioselectivity dis-
(39) Brunner, H.; Prommesberger, M. Tetrahedron: Asymmetry
1998, 9, 3231.

1748 Organometallics, Vol. 22, No. 8, 2003
Brunner et al.
trometer (250 MHz) and Bruker ARX 400 spectrometer (400
MHz). Elemental analyses: Elementar Vario EL III. X-ray
structural analyses: STOE-IPDS diffractometer (Mo KR radia-
tion, 173 K (Oxford Cryosystems Cooler,40 graphite monochro-
mator), SIR-9741 and SHELXL-97.42 [(η6-p-cymene)RuCl2]2,
[(η6-benzene)RuCl2]2, [(η6-mesitylene)RuCl2]2, [(η6-hexameth-
ylbenzene)RuCl2]2, and [(η6-p-cymene)OsCl2]2 were prepared
as published.43-47
P r ep a r a tion of Com p ou n d s HLL*-1-HLL*-8. All the
chiral salicylaldiminates, except HLL*-3 and HLL*-6, which
were new compounds, were synthesized according to the
literature.48-53
(S)-(+)-(1-Cycloh exylet h yl)sa licyla ld im in e (H LL*-3).
Salicylaldehyde (2.10 mL, 2.44 g, 20.0 mmol) was dissolved in
5 mL of methanol, and (S)-(1-cyclohexylethyl)amine (2.89 mL,
2.50 g, 19.6 mmol) was added. The mixture was heated to 55-
60 °C for 2 h. The solvent was removed, and the oily residue
was distilled under reduced pressure, giving a slightly yellow
liquid. Yield: 3.82 g (84%). Bp: 113-115 °C/2 Torr. IR (neat):
ν 3030 w, 2940 m, 2900 s, 2820 m (C-H), 1610 s (CdN), 1560
F igu r e 3. Conversion and enantiomeric excess of the
isomerization product B as a function of time for the
catalysis of Scheme 4.
appeared completely (entries 13 and 14). There is no
explanation for this behavior.
In a study of the solvent dependence of the olefin
isomerization according to Scheme 4, an “alcohol prob-
lem” had been encountered. If methanol in the standard
solvent mixture THF/methanol was replaced by ethanol
(or other alcohols), the enantioselectivity disappeared.39
In the present study we confirmed this result with
complex 5 as the catalyst. Under standard conditions
using THF/ethanol (2:1) instead of THF/methanol (2:
1), the catalytic activity dropped to about 60% conver-
sion, the amount of hydrogenation product reached a
maximum of 21%, and the enantioselectivity vanished.9
To investigate the reaction kinetics of the catalysis
of Scheme 4, complex 1 (124 mg, 0.25 mmol) was
dissolved in 30 mL of THF/methanol (2:1) and activated
with NaBH4 (250 mg, 6.60 mmol). Then 2-n-butyl-4,7-
dihydro-1,3-dioxepin (A; 8.60 mL, 50.0 mmol) was
added. In defined time intervals 3 mL was taken from
the reaction mixture and worked up as described in the
Experimental Section. Figure 3 shows the rise of yield
and enantiomeric excess of the isomerization product
B as a function of time.
After a period of slower reaction rate in the first 1-2
h, the yield of isomerization product B increased almost
linearly. After 5-6 h conversion was quantitative. Using
linear regression between 2.5 and 5 h the reaction rate
was calculated as 37.6 ( 2.2 h-1. The time dependence
of the enantiomeric excess showed the same sigmoidal
curve as the conversion (Figure 3). There was an
increase of the enantiomeric excess during the reaction,
and values around 50% ee were only obtained at the
end of the reaction. Usually, the enantiomeric excess is
constant during a reaction. The increase observed here
will allow an improvement of the enantioselectivity, in
particular, after the mechanism of the catalysis has
been established.
1
3
m (CdC). H NMR (250 MHz, CDCl3, TMS): δ 1.25 (d, J )
6.4 Hz, 3H, CH3), 1.82-0.86 (min, 11H, H cyclohexyl), 3.09
3
3
3
3
(dq, J ) J ) 6.4 Hz, 1H, dNCH), 6.86 (ddd, J ) 7.7 Hz, J
4
) 7.2 Hz, J ) 1.1 Hz, 1H, Sal H4), 6.98-6.93 (min, 1H, Sal
H6), 7.33-7.21 (m, 2H, Sal H3, Sal H5), 8.27 (s, 1H, NdCH),
13.82 (bs, 1H, OH). MS (EI, 70 eV): m/z (relative intensity)
231 (54) [M], 148 (100), 121 (23). [R]D (c ) 1.30, EtOH): +372°.
Anal. Calcd for C15H21NO (231.3): C, 77.88; H, 9.15; N, 6.05.
Found: C, 77.60; H, 9.12; N, 5.98.
(S)-(+)-N-[1-(1-((Ben zyloxy)ca r bon yl)-2-m eth ylp r op yl)]-
sa licyla ld im in e (HLL*-6). The salt (S)-benzyl valinate/p-
toluenesulfonic acid54 (5.65 g, 14.9 mmol) was suspended in
100 mL of methanol, and NaOMe (805 mg, 14.9 mmol) was
added. To the resulting clear solution was added dropwise
salicylaldehyde (156 mL, 1.82 g, 14.9 mmol), and the mixture
was stirred at 55-60 °C for about 30 min. After it was cooled
to room temperature, the yellow solution was stirred for 16 h.
The solvent was removed. The residue was dissolved in 50 mL
of CH2Cl2 and the solution washed three times with 70 mL of
water. The organic layer was dried over Na2SO4, and the
solvent was removed. Adding 50 mL of petroleum ether to the
yellow oil and cooling to -30 °C resulted in the formation of
light yellow needles. Yield: 2.68 g (58%). Mp: 52-53 °C. IR
(KBr, cm-1): ν 3040 w, 2970 m, 2880 m (C-H), 1730 vs (Cd
O), 1630 vs (CdN), 1580 m (CdC). 1H NMR (250 MHz, CDCl3,
TMS): δ 0.94 (d, 3J ) 6.8 Hz, 3H, CH(CH3)2), 0.95 (d, 3J ) 6.8
3
3
Hz, 3H, CH(CH3)2), 2.39 (dsept, J ) 6.2 Hz, J ) 6.8 Hz, 1H,
CH(CH3)2), 3.76 (d, 3J ) 6.2 Hz, 1H, dNCH), 5.20 (s, 2H, OCH2-
Ph), 6.89 (ddd, J ) 7.7 Hz, J ) 7.2 Hz, J ) 1.1 Hz, 1H, Sal
3
3
4
(40) Cosier, J .; Glazer, A. M. J . Appl. Crystallogr. 1986, 19, 105.
(41) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A. J .
Appl. Crystallogr. 1993, 26, 343.
(42) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; University of Go¨ttingen, Go¨ttingen, Germany, 1997.
(43) Winkhaus, G.; Singer, H.; Kricke, M. Z. Naturforsch. 1966, 21B,
11.09.
(44) Winkhaus, G.; Singer, H. J . Organomet. Chem. 1967, 7, 487.
(45) Bennett, M. A.; Huang, T. N.; Matheson, T. W.; Smith, A. K.
Inorg. Synth. 1982, 21, 74.
(46) Bennett, M. A.; Smith, A. K. J . Chem. Soc., Dalton Trans. 1974,
2, 233.
Exp er im en ta l Section
(47) Werner, H.; Zenkert, K. J . Organomet. Chem. 1988, 345, 151.
(48) Smith, H. E., Cook, S. C.; Warren, M. E. J . Org. Chem. 1964,
29, 2265.
(49) Warren, M. E.; Smith, H. E. J . Am. Chem. Soc. 1965, 87, 1757.
(50) Desimoni, G.; Faita, G.; Mellerio, G.; Righetti, P. P.; Zanelli,
C. Gazz. Chim. Ital. 1992, 122, 269.
(51) Grigg, R.; Gunaratne, H. Q. N.; Sridharan, V. Tetrahedron 1987,
43, 5887.
(52) Grigg, R.; Gunaratne, H. Q. N.; Kemp, J . J . Chem. Soc., Perkin
Trans. 1 1984, 41.
(53) Amomraksa, K.; Grigg, R.; Nimal Gunaratne, H. Q.; Kemp, J .;
Sridharan, V. J . Chem. Soc., Perkin Trans. 1 1987, 2285.
(54) Zervas, L.; Winitz, M.; Greenstein, J . P. J . Org. Chem. 1957,
22, 1515.
Gen er a l Rem a r k s. All manipulations and reactions, in-
cluding metal compounds, were carried out under an inert
atmosphere of dry nitrogen using standard Schlenk tech-
niques. Most of the commercially available reagents were used
without further purification. Solvents were dried by standard
methods and distilled prior to use. Melting points: Bu¨chi SMP
20, not corrected. IR spectra: Beckman IR 4240 spectrometer
(KBr pellets). Mass spectra: Finnigan MAT 311 A (EI, electron
impact method) and Finnigan MAT 95 (FD, field desorption
method). Optical rotations: Perkin-Elmer 241 polarimeter at
room temperature. 1H NMR spectra: Bruker AC 250 spec-

Optically Active Transition Metal Complexes
Organometallics, Vol. 22, No. 8, 2003 1749
3
H4), 7.01-6.96 (m, 1H, Sal H6), 7.39-7.24 (m, 7H, CH2Ph,
Sal H3, Sal H5), 8.31 (s, 1H, NdCH), 13.14 (bs, 1H, OH). MS
(EI, 70 eV): m/z (relative intensity) 311 (59) [M], 176 (83)
[M - CO2CH2Ph], 91.1 (100) [CH2Ph]. [R]D (c ) 1.03, CH2Cl2):
+1.36°. Anal. Calcd for C19H21NO3 (311.4): C, 73.29; H, 6.80,
N, 4.50. Found: C, 73.07; H, 7.17; N, 4.50.
1H, Sal H4), 7.00-6.89 (m, 2H, Sal H3, Sal H6), 7.18 (ddd, J
) 8.6 Hz, 3J ) 6.8 Hz, 4J ) 1.6 Hz, 1H, Sal H5), 7.76 (7.85) (s,
1H, NdCH). MS (FD, CH2Cl2): m/z (relative intensity) 491
(100) [M] relative to 102Ru. [R]D (c ) 0.06, CH2Cl2): -1000°.
Anal. Calcd for C23H32ClNO2Ru (491.0): C, 56.26; H, 6.57; N,
2.85. Found: C, 56.23; H, 6.47; N, 2.74.
P r ep a r a tion of th e Com p lexes [(η6-a r en e)Ru (LL*)Cl].
[(η6-p-cymene)Ru(LL*-1)Cl] (1) and [(η6-benzene)Ru(LL*-1)-
Cl] (9) were synthesized according to the literature.25 The novel
complexes were synthesized using the following general pro-
cedure: 2.10 mmol of the appropriate ligand HLL*-1-HLL*-8
was dissolved in 20 mL of absolute CH2Cl2, and KOtBu (2.10
mmol) was added at room temperature. The mixture was
stirred for 30 min. After the suspension was cooled to -78 °C,
1.00 mmol of [(η6-arene)RuCl2]2 was added. The solution was
stirred for 16 h, in the course of which the reaction mixture
was warmed to room temperature. The volume of the solution
was reduced to 50%. The solution was filtered over a short
column loaded with Celite and SiO2. The purification of the
crude product is specified for the individual complexes.
[(η6-p-cym en e)Ru (LL*-2)Cl] (2). Recrystallization was
carried out from CH2C12/ether/hexane. Yield: 864 mg (79%),
Mp: 212 °C dec. IR (KBr, cm-l): ν 3040 w, 2950 m, 2860 w
(C-H), 1610 s, 1590 m (CdN). 1H NMR (250 MHz, CDCl3,
TMS; signals of the minor diastereomer are given in paren-
theses when different from those of the major diastereomer):
[(η6-p-cym en e)Ru (LL*-5)Cl] (5). Recrystallization was
carried out from toluene/petroleum ether. Yield: 486 mg (96%).
Mp: 136 °C dec. IR (KBr, cm-1): ν 3060 w, 2980 m, 2890 w
(C-H), 1750 s, 1730 s (CdO), 1625 s (CdN). 1H NMR (250
MHz, CDCl3, TMS; signals of the minor diastereomer are given
in parentheses when different from those of the major dias-
3
tereomer): δ 1.01 (1.08) (d, J ) 6.5 Hz, 3H, CH(CH3)2), 1.04
3
(1.13) (d, J ) 6.5 Hz, 3H, CH(CH3)2), 1.09 (1.23) (d, J ) 7.0
3
Hz, 3H, CH(CH3)2 p-cymene), 1.21 (1.27) (d, J ) 7.0 Hz, 3H,
CH(CH3)2 p-cymene), 2.15 (2.22) (s, 3H, CH3 p-cymene), 2.42
3
3
(dsept, J ) 10.1 Hz, J ) 6.5 Hz, 1H, CH(CH3)2), 2.77 (2.65)
(sept, 3J ) 7.0 Hz, 1H, CH(CH3)2 p-cymene), 3.90 (3.73) (s, 3H,
OCH3), 4.80 (4.61) (d, 3J ) 10.1 (11.3) Hz, 1H, dNCH), 5.14
3
(5.02) (d, J ) 5.5 Hz, 1H, H p-cymene), 5.43-5.33 (m, 3H, H
3
4
p-cymene), 6.43 (6.42) (ddd, 3 ) 7.8 Hz, J ) 6.8 Hz, J ) 1.1
Hz, 1H, Sal H4), 7.01-6.91 (m, 2H, Sal H3, Sal H6), 7.17 (7.16)
3
3
4
(ddd, J ) 8.6 Hz, J ) 6.8 Hz, J ) 1.9 Hz, 1H, Sal H5), 7.95
(8.03) (s, 1H, NdCH). MS (FD, CH2Cl2): m/z (relative inten-
sity) 505 (100) [M] relative to 102Ru. [R]D (c ) 0.16, CH2Cl2):
+316°. Anal. Calcd for C23H30ClNO3Ru (505.0): C, 54.70; H,
5.99; N, 2.77. Found: C, 54.60; H, 6.06; N, 2.79.
3
3
δ 0.95 (d, J ) 6.9 Hz, 3H, CH3 iPr), 1.08 (d, J ) 6.9 Hz, 3H,
CH3 iPr), 1.88 (d, 3J ) 7.0 Hz, 3H, CH3), 2.03 (s, 3H, CH3
[(η6-p-cym en e)Ru (LL*-6)Cl] (6). Recrystallization from
CH2Cl2/petroleum ether. Yield: 395 mg (68%), Mp: 56 °C dec.
IR (KBr, cm-1): ν 3040 w, 2970 m, 2940 w, 2880 w (C-H),
1740 s, (CdO), 1620 s (CdN). 1H NMR (250 MHz, CDCl3, TMS;
signals of the minor diastereomer are given in parentheses
when different from those of the major diastereomer): δ 0.97
(1.04) (d, 3J ) 6.9 Hz, 3H, CH(CH3)2 p-cymene), 1.01 (1.23) (d,
i
p-cymene), 2.63 (sept, 3J ) 6.9 Hz, 1H, CH Pr), 5.05/4.23 (AB,
3J ) 5.5 Hz, 2H, H p-cymene), 5.23/4.68 (AB, 3J ) 5.5 Hz, 2H,
H p-cymene), 6.50 (ddd, 3J ) 7.9 Hz, 3J ) 6.7 Hz, 4J ) 1.0 Hz,
3
3
1H, Sal H4), 6.75 (q, J ) 7.0 Hz, 1H, dNCH), 7.01 (d, J )
3
4
8.5 Hz, 1H, Sal H6), 7.08 (dd, J ) 7.9 Hz, J ) 1.8 Hz, 1H,
3
3
4
Sal H3), 7.22 (ddd, J ) 8.5 Hz, J ) 6.7 Hz, J ) 1.8 Hz, 1H,
Sa H5), 7.74-7.55 (m, 4H, H naphthyl), 8.02-7.89 (m, 2H, H
naphthyl), 8.12 (s, 1H, NdCH), 8.22 (d, 1H, 3J ) 8.3 Hz, H
naphthyl). MS (FD, CH2Cl2): m/z (relative intensity) 545 (100)
[M] relative to 102Ru. [R]D (c ) 0.05, CH2Cl2): -180°. Anal.
Calcd for C29H30ClNORu (545.9): C, 63.81; H, 5.54; N, 2.57.
Found: C, 64.16; H, 5.44; N, 2.41.
3
3J ) 6.6 Hz, 3H, CH(CH3)2), 1.02 (1.24) (d, J ) 6.6 Hz, 3H,
CH(CH3)2), 1.13 (1.11) (d, 3J ) 6.9 Hz, 3H, CH(CH3)2 p-
3
cymene), 2.02 (2.18) (s, 3H, CH3 p-cymene), 2.42 (dsept, J )
10.1 Hz, 3J ) 6.6 Hz, 1H, CH(CH3)2), 2.68 (2.78) (sept, 3J )
6.9 Hz, 1H, CH(CH3)2 p-cymene), 4.78 (4.65) (d, 3J ) 10.1 (11.1)
Hz, 1H, dNCH), 5.43-4.96 (m, 4H, H p-cymene), 5.43/5.25
2
3
[(η6-p-cym en e)Ru (LL*-3)Cl] (3). Precipitation was carried
out with petroleum ether from a CH2Cl2 solution. Yield: 170
mg (17%). Mp: 81-83 °C dec. IR (KBr, cm-1): ν 3080 w, 2940
s, 2920 w, 2870 m (C-H), 1625 s, 1605 m (CdN). 1H NMR
(250 MHz, CDCl3, TMS; signals of the minor diastereomer are
given in parentheses when different from those of the major
(AB, J ) 11.8 Hz, 2H, CH2Ph), 6.43 (6.42) (ddd, J ) 7.8 Hz,
3J ) 6.8 Hz, J ) 1.0 Hz, 1H, Sal H4), 7.01-6.90 (m, 2H, Sal
4
3
3
4
H3, Sal H6), 7.17 (7.18) (ddd, J ) 8.7 Hz, J ) 6.8 Hz, J )
1.9 Hz, 1H, Sal H5), 7.51-7.31 (m, 5H, CH2Ph), 7.96 (8.06) (s,
1H, NdCH). MS (FD, CH2Cl2): m/z (relative intensity) 581
(100) [M] relative to 102Ru. [R]D (c ) 0.11, CH2Cl2): +202°.
Anal. Calcd for C29H34ClNO3Ru (581.1): C, 59.94; H, 5.90; N,
2.41. Found: C, 59.33; H, 5.85; N, 2.20.
3
diastereomer): δ ) 1.13 (1.15) (d, J ) 7.0 Hz, 3H, CH3 iPr),
3
1.27 (1.26) (d, J ) 7.0 Hz, 3H, CH3 iPr), 1.42-0.87 (m, 5H, H
3
cyclohexyl), 1.48 (1.49) (d, J ) 6.8 Hz, 3H, CH3), 2.09-1.59
[(η6-p-cym en e)Ru (LL*-7)Cl] (7). Recrystallization was
carried out from toluene/petroleum ether. Yield: 235 mg (42%).
Mp: 169 °C dec. IR (KBr, cm-1): ν 3040 w, 2980 m, 2930 w
(C-H), 1750 s (CdO), 1620 s (CdN). 1H NMR (250 MHz,
CDCl3, TMS; signals of the minor diastereomer are given in
parentheses when different from those of the major diastere-
(m, 6H, H cyclohexyl), 2.17 (2.21) (s, 3H, CH3 p-cymene), 2.82
(sept, 3J ) 7.0 Hz, CH(CH3)2), 4.39-4.15 (m, 1H, dNCH),
5.45-4.93 (m, 4H, H p-cymene), 6.41 (6.39) (ddd, 3J ) 7.8 Hz,
4
3J ) 6.8 Hz, J ) 1.1 Hz, 1H, Sal H4), 6.98-6.85 (m, 2H, Sal
H3, Sal H6), 7.19-7.10 (m, 1H, Sal H5), 7.69 (7.60) (s, 1H,
NdCH). MS (FD, CH2Cl2): m/z (relative intensity) 501 (100)
[M] relative to 102Ru. [R]D (c ) 0.10, CH2Cl2): -160°. Anal.
Calcd for C25H34ClNORu (501.1): C, 59.93; H, 6.84; N, 2.80.
Found: C, 60.53; H, 7.03; N, 2.84.
omer): δ 1.11 (0.92) (d, J ) 6.9 Hz, 3H, CH3 iPr), 1.19 (1.13)
3
(d, 3J ) 6.9 Hz, 3H, CH3 iPr), 2.17 (2.05) (s, 3H, CH3 p-cymene),
3
i
2
2.77 (2.57) (sept, J ) 6.9 Hz, 1H, CH Pr), 3.20 (dd, J ) 12.6
Hz, 3J ) 11.4 Hz, CH2Ph), 3.57 (dd, 2J ) 12.6 Hz, 3J ) 3.2 Hz,
CH2Ph), 3.78 (3.73) (s, 3H, OCH3), 5.49-4.65 (m, 5H, H
[(η6-p-cym en e)Ru (LL*-4)Cl] (4). Recrystallization was
carried out from CH2Cl2/ether/hexane. Yield: 113 mg (12%),
Mp: 153 °C dec. IR (KBr, cm-1): ν 3600-3100 m (O-H), 3010
3
3
p-cymene, dNCH), 6.46 (6.47) (ddd, J ) 7.9 Hz, J ) 6.8 Hz,
4J ) 1.1 Hz, 1H, Sal H4), 7.02-6.92 (m, 2H, Sal H3, Sal H6),
7.48-7.09 (m, 6H, Ph H, Sal H5), 8.06 (8.28) (s, 1H, NdCH).
MS (FD, CH2Cl2): m/z (relative intensity) 553 (100) [M]
relative to 102Ru. [R]D (c ) 0.10, CH2Cl2): +40.2°. Anal. Calcd
for C27H30ClNO3Ru (553.1): C, 58.64; H, 5.47; N, 2.53. Found:
C, 58.33; H, 5.34; N, 2.36.
1
w, 2930 s, 2900 m, 2840 w (C-H), 1600 s, 1580 m (CdN). H
NMR (250 MHz, CDCl3, TMS; signals of the minor diastereo-
mer are given in parentheses when different from those of
the major diastereomer): δ 1.18-1.06 (m, 9H, CH3 iPr,
3
CH2CH(CH3)2), 1.26 (d, J ) 7.0 Hz, 3H, CH3 iPr), 1.94-1.72
(min, 3H, CH2CH(CH3), CH2OH), 2.25 (s, 3H, CH3 p-cymene),
(η6-p-cym en e)Ru (LL*-8)Cl] (8). Recrystallization was car-
ried out from toluene/petroleum ether. Yield: 420 mg (78%),
Mp: 158 °C dec. IR (KBr, cm-1): ν 3040 w, 2980 m, 2880 w
(C-H), 1745 s (CdO), 1620 s (CdN). 1H NMR (250 MHz,
CDCl3, TMS; signals of the minor diastereomer are given in
2.76 (sept, 3J ) 7.0 Hz, 1H, CH iPr), 3.74-3.61 (m, 1H,
CH2CH(CH3)2), 4.09-3.91 (m, 2H, CH2OH),
4.65-4.53 (m, 1H, dNCH),
3
5.00 (d, J ) 5.5 Hz, 1H, H p-cymene), 5.53-5.41 (m, 3H, H
3
3
4
p-cymene), 6.43 (ddd, J ) 7.8 Hz, J ) 6.8 Hz, J ) 1.1 Hz,

1750 Organometallics, Vol. 22, No. 8, 2003
Brunner et al.
parentheses when different from those of the major diastere-
above for the corresponding ruthenium complexes using 0.50
mmol of [(η6-p-cymene)OsCl2]2 and 1.00 mmol of the respective
ligand.
3
3
omer): δ 1.10 (1.09) (d, J ) 6.8 Hz, 3H, CH3 iPr), 1.23 (d, J
) 6.8 Hz, 3H, CH3 iPr), 2.18 (2.15) (s, 3H, CH3 p-cymene), 2.83
i
(sept, 3J ) 6.8 Hz, 1H, CH Pr), 4.02 (3.77) (s, 3H, OCH3), 5.11
[(η6-p -cym en e)Os(LL*-1)Cl] (13). Recrystallization was
carried out from toluene/CH2Cl2/petroleum ether. Yield: 245
mg (84%), Mp: 190-195 °C dec. IR (KBr, cm-l): ν 3060 w,
3
3
(4.98) (d, J ) 5.5 Hz, 1H, H p-cymene), 5.31 (d, J ) 5.5 Hz,
3
1H, H p-cymene), 5.46 (d, J ) 5.5 Hz, 1H, H p-cymene), 5.51
(d, J ) 5.5 Hz, 1H, H p-cymene), 6.46-6.31 (m, 1H, Sal H4),
3
1
3020 w, 2960 m, 2820 w (C-H), 1615 s (CdN). H NMR (250
6.67 (s, 1H, dNCH), 7.00-6.72 (m, 2H, Sal H3, Sal H6), 7.13
(ddd, 3J ) 8.6 Hz, 3J ) 6.8 Hz, 4J ) 1.7 Hz, 1H, Sal H5), 7.55-
7.28 (m, 6H, Ph H, NdCH). MS (FD, CH2Cl2): m/z (relative
intensity) 539 (100) [M] relative to 102Ru. [R]D (c ) 0.11, CH2-
Cl2): +18.3°. Anal. Calcd for C26H28ClNO3Ru (539.0): C, 57.93;
H, 5.24; N, 2.60. Found: C, 57.93; H, 5.08; N, 2.47.
MHz, CDCl3, TMS; signals of the minor diastereomer are given
in parentheses when different from those of the major dias-
tereomer): δ 1.06 (1.18) (d, 3J ) 6.9 Hz, 3H, CH3 iPr), 1.20
(1.29) (d, 3J ) 6.9 Hz, 3H, CH3 iPr), 1.81 (1.84) (d, 3J ) 7.0
Hz, 3H, CH3), 2.23 (2.25) (s, 3H, CH3 p-cymene), 2.56 (2.72)
3
i
(sept, J ) 6.9 Hz, 1H, CH Pr), 5.89-5.23 (min, 5H, dNCH,
[(η6-m esitylen e)Ru (LL*-1)Cl] (10). Recrystallization was
carried out from CH2Cl2/hexane. Yield: 348 mg (72%). Mp: 172
°C dec. IR (KBr, cm-1): ν 3030 w, 2980 w, 2930 w (C-H), 1620
3
3
4
H p-cymene), 6.46 (6.38) (ddd, J ) 7.8 Hz, J ) 6.8 Hz, J )
1.0 Hz, 1H, Sal H4), 7.01-6.75 (m, 2H, Sal H3, Sal H6), 7.73-
7,17 (m, 6H, Ph H, Sal H5), 7.91 (7.66) (s, 1H, NdCH). MS
(FD, CH2Cl2): m/z (relative intensity) 585 (100) [M] relative
1
s, 1600 m (CdN). H NMR (250 MHz, CDCl3, TMS; signals of
to 192Os. [R]D (c ) 0.10, CH2Cl2): +48°. Anal. Calcd for C25H28
-
the minor diastereomer are given in parentheses when differ-
3
ent from those of the major diastereomer): δ 1.72 (d, J ) 7.2
ClNOOs (584.2): C, 51.40; H, 4.83; N, 2.40. Found: C, 51.82;
H, 4.83; N, 2.43.
Hz, 3H, CH(CH3)), 1.96 (2.14) (s, 9H, C6H3(CH3)3), 4.68 (4.87)
3
[(η6-p-cym en e)Os(LL*-5)Cl] (14). Recrystallization was
carried out from toluene/petroleum ether. Yield: 184 mg (62%),
Mp: 115 °C dec. IR (KBr, cm-1): ν 3060 w, 2970 m, 2880 w
(C-H), 1730s (CdO), 1610 s (CdN). 1H NMR (250 MHz,
CDCl3, TMS; signals of the minor diastereomer are given in
parentheses when different from those of the major diastere-
omer): δ 1.02 (1.04) (d, 3J ) 6.7 Hz, 3H, CH(CH3)2), 1.10 (1.14)
(d, 3J ) 7.0 Hz, 3H, CH(CH3)2 p-cymene), 1.15 (d, 3J ) 6.7 Hz,
3H, CH(CH3)2), 1.24 (1.28) (d, 3J ) 7.0 Hz, 3H, CH(CH3)2
(s, 3H, C6H3(CH3)3), 5.78 (5.56) (q, J ) 7.2 Hz, 1H, dNCH),
6.49 (6.42) (ddd, 3J ) 7.7 Hz, 3J ) 6.9 Hz, 4J ) 1.2 Hz, 1H,
Sal H4), 7.07-6.83 (m, 2H, Sal H3, Sal H6), 7.19 (7.15) (ddd,
3
4
3J ) 8.5 Hz, J ) 6.9 Hz, J ) 1.8 Hz, 1H, Sal H5), 7.61-7.23
(m, 5H, Ph H), 8.02 (s, 1H, NdCH). MS (FD, CH2Cl2): m/z
(relative intensity) 481 (100) [M] relative to 102Ru. [R]D (c )
0.04, CH2Cl2): -485°. Anal. Calcd for C24H26ClNO3Ru (481.0):
C, 59.93; H, 5.45; N, 2.91. Found: C, 59.46; H, 5.47; N, 2.83.
[(η6-h exa m eth ylben zen e)Ru (LL*-1)Cl] (11). Recrystal-
lization was carried out from CH2Cl2/hexane. Yield: 115 mg
(22%). Mp: 198 °C dec. IR (KBr, cm-1): ν 3040 w, 3000 w, 2900
3
p-cymene), 2.24 (2.30) (s, 3H, CH3 p-cymene), 2.48 (dsept, J
3
3
) 10.3 Hz, J ) 6.7 Hz, 1H, CH(CH3)2), 2.63 (2.64) (sept, J )
7.0 Hz, 1H, CH(CH3)2 p-cymene), 3.85 (3.74) (s, 3H, OCH3),
1
w (C-H), 1600 s, 1580 m (CdN). H NMR (250 MHz, CDCl3,
3
TMS; signals of the minor diastereomer are given in paren-
theses when different from those of the major diastereomer):
δ 1.82 (d, 3J ) 7.1 Hz, 3H, CH3), 1.96 (2.03) (s, 18H, C6(CH3)6),
5.59 (5.47) (q, 3J ) 7.1 Hz, 1H, CH), 6.37 (ddd, 3J ) 7.7 Hz, 3J
4.76 (4.52) (d, J ) 10.3 (11.2) Hz, 1H, dNCH), 5.50 (5.39) (d,
3J ) 5.4 Hz, 1H, H p-cymene), 5.88-5.63 (m, 3H, H p-cymene),
3
3
4
6.47 (ddd, J ) 7.9 Hz, J ) 6.7 Hz, J ) 1.1 Hz, 1H, Sal H4),
6.91-6.85 (m, 1H, Sal H6), 7.07-7.03 (m, 1H, Sal H3), 7.25
(7.26) (ddd, 3J ) 8.6 Hz, 3J ) 6.7 (6.9) Hz, 4J ) 1.9 Hz, 1H,
Sal H5), 8.05 (8.14) (s, 1H, NdCH). MS (FD, CH2Cl2): m/z
(relative intensity) 595 (100) [M] relative to 192Os. [R]D
(c ) 0.10, CH2Cl2): +308°. Anal. Calcd for C23H30ClNO3Os
(594.2): C, 46.50; H, 5.09; N, 2.36. Found: C, 46.36; H, 5.00;
N, 2.40.
4
3
4
) 6.8 Hz, J ) 1.2 Hz, 1H, Sal H4), 6.85 (dd, J ) 7.7 Hz, J
3
) 1.8 Hz, 1H, Sal H3), 6.96 (d, J ) 8.6 Hz, 1H, Sal H6), 7.14
(ddd, 3J ) 8.6 Hz, 3J ) 6.8 Hz, 4J ) 1.8 Hz, 1H, Sal H5), 7.49-
7.30 (m, 5H, Ph H), 7.73 (s, 1H, NdCH). MS (FD, CH2Cl2):
m/z (relative intensity) 523 (100) [M] relative to 102Ru. [R]D (c
) 0.06, CH2Cl2): -157°. Anal. Calcd for C27H32ClNO3Ru
(523.1): C, 62.00; H, 6.17; N, 2.68. Found: C, 61.86; H, 6.23;
N, 2.84.
Ca ta lytic Dou ble-Bon d Isom er iza tion . The catalytic
isomerizations were carried out under an atmosphere of dry
nitrogen. The catalyst (0.025 mmol) was dissolved in 3 mL of
THF/MeOH (2:1). NaBH4 (25.0 mg, 1.32 mmol) was added,
followed by 0.86 mL (5.00 mmol) of 2-n-butyl-4,7-dihydro-1,3-
dioxepin. To remove the developing hydrogen, a stream of
nitrogen was passed over the solution for 15 min. After 24 h
the reaction was stopped by bubbling air through the solution.
The solvent was evaporated, and the oily residue was purified
by distillation under reduced pressure (70 °C, 2-3 Torr).
Conversion was determined by 1H NMR spectroscopy (250
MHz, CDCl3). The integrals of the following signals were
used: starting material A, multiplet (δ 5.77-5.65 ppm);
product B, doublet of doublets (δ 6.35 ppm); hydrogenation
product C, multiplet (δ 3.93-3.55 ppm). The enantiomer
analysis was carried out by gas chromatography: HP 5890 A,
Restek Rt-PâDEXcst column (30 m, 0.32 mm i.d.). Conditions:
carrier gas H2, 82 °C isothermal. Retention times: (-)-enantio-
mer of B, 15.2 min; (+)-enantiomer of B, 16.0 min; hydrogena-
tion product C, 16.9 min; starting material A, 19.3 min.
[(η6-p-cym en e)Ru (LL*-5)I] (12). Complex 5 (90.0 mg, 0.18
mmol) was dissolved in 20 mL of absolute MeOH, and NaI
(270 mg, 180 mmol) was added. The mixture was stirred for 3
h at room temperature. The solvent was evaporated, and the
residue was dissolved in CH2Cl2 and filtered through Celite.
Removing the solvent yielded the analytically pure dark red
powder 12. Yield: 99.6 mg (94%). Mp: 160 °C dec. IR (KBr,
cm-1): ν 2980 m, 2880 w (C-H), 1745 s (CdO), 1620 s (CdN).
1H NMR (250 MHz, CDCl3, TMS; signals of the minor
diastereomer are given in parentheses when different from
those of the major diastereomer): δ 1.03 (1.08) (d, 3J ) 6.5
3
Hz, 3H, CH(CH3)2), 1.09 (1.15) (d, J ) 6.9 Hz, 3H, CH(CH3)2
p-cymene), 1.16 (1.22) (d, 3J ) 6.5 Hz, 3H, CH(CH3)2), 1.26
(1.31) (d, 3J ) 6.9 Hz, 3H, CH(CH3)2 p-cymene), 2.30 (2.38) (s,
3H, CH3 p-cymene), 2.50 (dsept, 3J ) 9.6 Hz, 3J ) 6.5 Hz, 1H,
CH(CH3)2), 2.93 (2.91) (sept, 3J ) 6.9 Hz, 1H, CH(CH3)2
3
p-cymene), 3.90 (3.75) (s, 3H, OCH3), 4.79 (4.52) (d, J ) 9.6
(10.9) Hz, 1H, dNCH), 5.70-4.91 (m, 4H, H p-cymene), 6.43
(6.42) (ddd, 3J ) 7.9 Hz, 3J ) 6.8 Hz, 4J ) 1.1 Hz, 1H, Sal
H4), 7.00-6.85 (m, 2H, Sal H3, Sal H6), 7.16 (7.15) (ddd, 3J )
Su p p or tin g In for m a tion Ava ila ble: Figures and tables
giving X-ray data for complexes 2, 5, 7, 8, and 12-14, including
atomic coordinates, displacement parameters, bond lengths
and angles, hydrogen coordinates, and hydrogen bonds. This
material is available free of charge via the Internet at
http://pubs.acs.org.
3
4
8.6 Hz, J ) 6.8 Hz, J ) 1.9 Hz, 1H, Sal H5), 7.78 (7.93) (s,
1H, NdCH). MS (FD, CH2Cl2): m/z (relative intensity) 597
(100) [M] relative to 102Ru. [R]D (c ) 0.10, CH2Cl2): +507°.
Anal. Calcd for C23H30ClNO3Ru (596.5): C, 46.31; H, 5.07; N,
2.35. Found: C, 45.98; H, 5.10; N, 2.25.
P r ep a r a tion of th e Com p lexes [(η6-p-cym en e)Os(LL*)-
Cl. The osmium complexes were synthesized as described
OM020964U