Synthesis of a configurationally stable three-legged piano-stool complex

Article abstract of DOI:10.1021/om980949i

Anchoring a phosphine and an enantiopure camphorpyrazole tether to an arene (PArN*) yields, after η⁶:η¹:η¹ coordination to ruthenium, [{η⁶:η¹:η¹-(PArN*)}-RuL] ²⁺ as a 1:1 mixture of diastereomers. These were separated and characterized by X-ray crystallography. The structure of the R,R_P,S_Ru diastereomer is depicted.

Full text of DOI:10.1021/om980949i

Organometallics 1999, 18, 1565-1568
1565
Syn th esis of a Con figu r a tion a lly Sta ble Th r ee-Legged
P ia n o-Stool Com p lex
Bruno Therrien, Adrian Ko¨nig, and Thomas R. Ward*
Department of Chemistry and Biochemistry, University of Berne, Freiestrasse 3,
CH-3000 Berne 9, Switzerland
Received November 24, 1998
Summary: Anchoring a phosphine and an enantiopure
camphorpyrazole tether to an arene (PArN*) yields, after
η6:η1:η1 coordination to ruthenium, [{η6:η1:η1-(PArN*)}-
RuL]2+ as a 1:1 mixture of diastereomers. These were
separated and characterized by X-ray crystallography.
The structure of the R,RP,SRu diastereomer is depicted.
Theoretical studies on the configurational stability of
coordinatively unsaturated two-legged piano-stool com-
plexes of the type [(ηn-CnHn)ML1L2] (n ) 5-7) suggest
that, although some of these indeed possess pyramidal
(and thus chiral-at-metal) ground-state geometries, the
computed inversion barriers are low, i.e., <15 kcal
mol-1, thus hampering their use as enantioselective
catalysts.16
In tr od u ction
In analogy to Tro¨ger’s base, we reasoned that incor-
poration of the metal in a “bicyclic” framework would
significantly raise the inversion barriers of the resulting
complexes. Tethering a phosphine and a pyrazole to an
arene yields a potential 10-electron donor (abbreviated
PArN*) with a pronounced electronic asymmetry. Upon
η6:η1:η1 coordination to Ru(II), a three-legged piano-stool
complex is formed: [{η6:η1:η1-(PArN*)}RuL]2+ (L )
weakly bound solvent). For the preliminary studies
reported herein, an enantiopure auxiliary was incorpo-
rated in the PArN* ligand, facilitating analysis and
diastereomer separation. Related complexes, devoid of
ligand-based chirality (i.e. camphorpyrazole replaced by
achiral pyrazole derivatives), are currently being stud-
ied in our laboratories as well.19
With the advent of electronically asymmetric biden-
tate ligands, the C2 dogma that had guided chemists in
the design of chiral ligands for enantioselective catalysis
for two decades was seriously questioned.1 Introducing
electronic asymmetry at the metal helps to desymme-
trize an incoming prochiral substrate not only by steric
factors but also through the electronic factors imposed
by the bidentate ligand.2 In this context, the role of
metal-based chirality resulting from coordination of a
C1-symmetric bidentate ligand to a metal template has
received little attention. We wish to report our prelimi-
nary results on the design, the synthesis, and the
characterization of configurationally stable, diastereo-
merically pure piano-stool complexes.
(14) Faller, J . W.; Mazzieri, M. R.; Nguyen, J . T.; Parr, J .; Tokunaga,
M. Pure Appl. Chem. 1994, 66, 1463.
(15) Gladysz, J . A.; Boone, B. J . Angew. Chem., Int. Ed. Engl. 1997,
36, 550.
Resu lts a n d Discu ssion
To address the question of the role of chirality at the
metal in enantioselective catalysis, we focus on pseudo-
tetrahedral three-legged piano-stool complexes. The
presence of an arene and a bidentate ligand leaves one
free site for substrate activation and functionalization.
Ever since the pioneering work of Brunner on chiral-
at-metal piano-stool complexes, many examples of syn-
thesis, resolution, and enantioselective stoichiometric
applications of chiral piano-stool complexes, devoid of
ligand-based chirality, have been published.3-15
(16) Ward, T. R.; Schafer, O.; Daul, C.; Hofmann, P. Organometallics
1997, 16, 3207.
(17) Therrien, B.; Ward, T. R.; Pilkington, M.; Hoffmann, C.;
Gilardoni, F.; Weber, J . Organometallics 1998, 17, 330.
(18) Crystal structure analysis of (R,RP,SRu)-7a and (R,SP,RRu)-7b:
Siemens SMART CCD diffractometer,20 T ) 293 K, Mo KR radiation
(0.710 73 Å). A complete hemisphere of data was scanned on ω (0.30)
with a run time of 60 s, at a detector resolution of 512 × 512 pixels
and a detector distance of 5.18 cm. A total of 1271 frames were collected
for each data set; the collected frames were processed with the SAINT
program,21 which automatically performs Lorentz and polarization
corrections. The structure was solved by direct methods, and the
refinement was done by full-matrix least squares of F2 using
SHELXL9622 (â-test version). (R,RP,SRu)-7a , C34H37F6N2O7PRuS2 (fw
) 895.82): orthorhombic, space group P212121, a ) 9.9095(4) Å, b )
18.3768(7) Å, c ) 20.7991(8) Å, V ) 3787.6(3) Å3, Z ) 4, Fcalcd ) 1.571
g cm-3, F(000) ) 1824, µ ) 0.645 mm-1, crystal size 0.06 × 0.11 ×
0.32 mm; 19 118 measured reflections ( -12 e h e 12, -22 e k e 18,
-23 e l e 24), 7137 unique reflections. Refinement of 556 variables
with anisotropic thermal parameters for all non-hydrogen atoms gave
R ) 0.0546, Rw ) 0.1368, and S ) 1.164; residual electron density
(1) Whitesell, J . K. Chem. Rev. 1989, 89, 1581.
(2) Ward, T. R. Organometallics 1996, 15, 2836.
(3) Brunner, H. Adv. Organomet. Chem. 1980, 18, 151.
(4) Brunner, H. Angew. Chem., Int. Ed. Engl. 1969, 8, 382.
(5) Brunner, H.; Aclasis, J .; Langer, M.; Steger, W. Angew. Chem.,
Int. Ed. Engl. 1974, 13, 810.
(6) Brunner, H.; Fisch, K.; J ones, P. G.; Salbeck, J . Angew. Chem.,
Int. Ed. Engl. 1989, 28, 1521.
(7) Davies, S. G. Pure Appl. Chem. 1988, 60, 13.
(8) Davies, S. G. Aldrichim. Acta 1990, 23, 31.
(9) Faller, J . W.; Lambert, C.; Mazzieri, M. R. J . Organomet. Chem.
1990, 383, 161.
(10) Faller, J . W.; Linebarrier, D. L. J . Am. Chem. Soc. 1989, 111,
1937.
(11) Faller, J . W.; Linebarrier, D. L. Organometallics 1990, 9, 3182.
(12) Faller, J . W.; Nguyen, J . T.; Ellis, W.; Mazzieri, M. R. Orga-
nometallics 1993, 12, 1434.
1.793, -0.442
895.82): monoclinic, space group P21; a ) 8.2085(1) Å, b ) 21.5806(4)
e . (R,SP,RRu)-7b , C34H37F6N2O7PRuS2 (fw )
Å-3
Å, c ) 11.372(6) Å, â ) 110.95(2)°, V ) 1881.34(4) Å3, Z ) 2, Fcalcd
)
1.581 g cm-3, F(000) ) 912, µ ) 0.649 mm-1, crystal size (0.10 × 0.18
× 0.27 mm); 9525 measured reflections ( -8 e h e 10, -24 e k e 27,
-14 e l e 13), 5998 unique reflections. Refinement of 494 variables
with anisotropic thermal parameters for all non-hydrogen atoms gave
R ) 0.0465, Rw ) 0.1001, and S ) 1.103; residual electron density
0.618, -0.385 e Å-3
.
(19) Therrien, B.; Ward, T. R. Angew. Chem., Int. Ed. Engl. 1999,
38, 405.
(13) Faller, J . W.; Ma, Y. Organometallics 1992, 11, 2726.
10.1021/om980949i CCC: $18.00 © 1999 American Chemical Society
Publication on Web 03/19/1999

1566 Organometallics, Vol. 18, No. 8, 1999
Notes
Inspection of molecular models led us to suggest that
the absolute configuration of the chirality at ruthenium
is opposite to that of the planar chirality. Thus (R,RP)-
6a and (R,SP)-6b should yield (R,RP,SRu)-[{η6:η1:η1-
(PArN*)}Ru(OH2)]2+ (7a ) and (R,SP,RRu)-[{η6:η1:η1-
(PArN*)}Ru(OH2)]2+ (7b), respectively.
Suitable crystals for X-ray analysis were obtained for
both diastereomers 7a and 7b from CHCl3.18 The
molecular structures of both diastereomers (R,RP,SRu)-
[{η6:η1:η1-(PArN*)}Ru(OH2)]2+ (7a ) and (R,SP,RRu)-[{η6:
η1:η1-(PArN*)}Ru(OH2)]2+ (7b) are presented in parts
a and b, respectively, of Figure 2. The quasi-enantiomer
relationship between 7a and 7b is emphasized. Relevant
bond lengths and angles for complexes 7 are collected
in Table 1. The bond lengths for both complexes 7 are
very similar to those reported for related, less strained
ruthenium piano-stool complexes.17,19 In particular, we
recently reported the structural characterization of
rac-[{η6:η1:η1-(PArN)}Ru(OH2)]2+ (A), where the cam-
phorpyrazole (of PArN*) is replaced by the electron-
deficient 3,5-bis(trifluoromethyl)pyrazole.19 For com-
parison, metrical data for this complex are included in
Table 1.
On the basis of molecular models, we anticipated that
pyrazole coordination for the sterically loaded diaste-
reomer 7a (C(CH3)2-bridge and CH3 of bridgehead of
camphor clashing with the phenyl group of the phos-
phine vs the CH2CH2 bridge of camphor for 7b) may be
problematic. The steric clash is reflected in the angles
around the ruthenium. For 7a both N(1)-Ru(1)-P(1)
and O(1)-Ru(1)-P(1) bite angles (101.1(2) and 94.0(1)°)
are significantly larger that for 7b (99.4(1) and 90.4-
(1)°). The 1,3-substitution pattern of the phosphine-
imine tethers on the arene imposes rather large N(1)-
Ru(1)-P(1) bite angles (101.1(2) and 99.4(1)°). Although
the η6-coordinated arene remains essentially planar
(greatest out-of-plane deviation: 0.0337 Å for C(3) of 7a
and 0.0393 Å for C(3) of 7b), the out-of-plane deviations
of C(7) and C(19) from the best plane defined by the
η6-coordinated arene are noteworthy: 0.228 and 0.4161
Å for 7a and 0.179 and 0.432 for 7b.
F igu r e 1. Preparation of diastereopure complexes 7.
Legend: (a) NaH, DMF, 60 °C, 3 h then 3-bromobenzyl
bromide, 60 °C 20 h (58%); (b) [Pd(PPh3)4], Bu3Sn(CHCH2),
toluene, 100 °C, 16 h (81%); (c) HPPh2, AIBN, CH2Cl2, hν
(63%); (d) 0.5 equiv of [(η6-C6H5CO2Et)RuCl2]2, CH2Cl2,
room temperature, 0.5 h (96%); (e) CH2Cl2, 110 °C, 24 h
(63%); (f) excess CF3SO3Tl, THF/H2O (91%).
The ligand synthesis is outlined in Figure 1. Nucleo-
philic substitution with enantiopure camphorpyrazole
1 on 3-bromobenzyl bromide yields exclusively the
1
regioisomer 2 (by H NMR). The phosphine donor was
incorporated in two steps: a Stille coupling between
bromoarene 2 and Bu3SnCHdCH2 yields the styrene
derivative 3, which regioselectively adds HPPh2 to afford
PArN* (4) in 30% overall yield. Phosphine coordination
to the labile [(η6-C6H5CO2Et)RuCl2]217 cleaves the dimer,
yielding [(η6-C6H5CO2Et)Ru{η1-(PArN*)}RuCl2] (5). Ther-
mal arene displacement cleanly affords [{η6:η1-(PArN*)}-
RuCl2] (6). Upon η6-coordination of the prochiral arene,
a planar chiral complex results. Despite the presence
of a bulky chiral auxiliary, complex 6 is formed as a 1/1
mixture of diastereomers (by 31P NMR). Flash chroma-
tography on silica gel with a 5/1 CH2Cl2/acetone solvent
mixture affords both (R,RP)-[{η6:η1-(PArN*)}RuCl2] (6a )
and (R,SP)-[{η6:η1-(PArN*)}RuCl2] (6b) in diastereo-
merically pure form. Treating complex 6a or 6b with
excess TlOTf in THF/H2O displaces both chlorides to
afford the aquo complex [{η6:η1:η1-(PArN*)}Ru(OH2)]2+
(7a or 7b, respectively). Upon pyrazole coordination, the
metal center becomes chiral. The presence of a single
31P NMR resonance for complexes 7a and 7b suggests
that the chiral center is formed diastereoselectively.
Con clu sion
Tethering two electronically asymmetric donors on an
arene affords the 10-electron donor ligand PArN*
adapted for piano-stool coordination geometries. Incor-
poration of an enantiopure camphor moiety in the
PArN* skeleton allows chromatographic separation of
the diastereomers resulting from η6: η1 coordination of
PArN* to Ru(II). Coordination of the pyrazole occurs
diastereoselectively to afford the chiral-at-metal [{η6:
η1:η1-(PArN*)}Ru(OH2)](OTf)2 (7). Both diastereomers
(R,RP,SRu)-7a and (R,SP,RRu)-7b were structurally char-
acterized. It appears that the chirality at the metal is
encoded by the planar chirality. All attempts to epimer-
ize the complex by either heating or irradiation have
yielded decomposition products rather than epimeriza-
tion products (by 31P NMR). We are currently testing
these complexes as Lewis acid catalysts for Diels-Alder
and Mukaiyama aldol reactions.
(20) SAINT, version 4; Siemens Energy and Automation Inc.,
Madison, WI, 1995.
(21) SHELXTL, version 5.03 (for Silicon Graphics); Program Library
for Structure Solution and Molecular Graphics; Siemens Analytical
Instruments Division, Madison, WI, 1995.
(22) Sheldrick, G. M. SHELXL, 1996; Program for the Refinement
of Crystal Structures; University of Go¨ttingen, Go¨ttingen, Germany,
1996.
Exp er im en ta l Section
(23) Lecloux, D. D.; Tokar, C. J .; Osawa, M.; Houser, R. P.; Keyes,
M. C.; Tolman, W. B. Organometallics 1994, 13, 2855. See also:
Brunner, H.; Scheck, T. Chem. Ber. 1992, 125, 701.
Syn th esis of 2-(3-Br om oben zyl)-7,8,8-tr im eth yl-4,5,6,7-
tetr a h yd r o-2H-4,7-m eth a n oin d a zole (2). To a NaH suspen-

Notes
Organometallics, Vol. 18, No. 8, 1999 1567
F igu r e 2. Molecular structures of [{η6:η1:η1-(PArN*)}Ru(OH2)]2+ (7): (a) (R,RP,SRu)-7a ; (b) (R,SP,RRu)-7b. Thermal ellipsoids
are at the 50% probability level.
Ta ble 1. Selected In ter a tom ic Dista n ces (Å),
An gles (d eg), a n d Tor sion An gles (d eg) for
(R,RP ,SRu )-[{η6:η1:η1-(P Ar N*)}Ru (OH2)]2+ (7a ) a n d
(R,SP ,RRu )-[{η6:η1:η1-(P Ar N*)}Ru (OH2)]2+ (7b) a s
Well a s r a c-[{η6:η1:η1-(P Ar N)}Ru (OH2)]2+ (A)19
(hexane/ethyl acetate 5/2) to afford vinylcamphorpyrazole (3;
3.8 g, 81% yield). 1H NMR (CDCl3): δ 7.26 (d, 3J H-H ) 7.7 Hz,
3
1H, CHar), 7.22 (dd, J H-H ) 7.0 Hz, 1H, CHar), 7.10 (s, 1H,
3
CHar), 6.99 (d, 1H, CHar), 6.88 (s, 1H, CHpyr), 6.63 (dd, J H-H
3
2
) 17.7 Hz and J H-H ) 11.0 Hz, 1H, CHvinyl), 5.64 (dd, J H-H
) 0.7 Hz, 1H, CH2-vinyl), 5.22 (dd, 2J H-H ) 16.0 Hz, 2H, CH2N),
5.18 (dd, 1H, CH2-vinyl), 2.73 (d, J H-H ) 4.1 Hz, 1H, CHcamp),
7a
7b
A
3
Ru(1)-P(1)
2.380(2)
2.144(5)
2.155(5)
2.197(7)
2.379(2)
2.145(5)
2.132(4)
2.192(7)
2.387(2)
2.163(4)
2.134(4)
2.186(5)
2.05 (m, 1H, CH2-camp), 1.84 (ddd, 1H, CH2-camp), 1.32 (s, 3H,
CH3-camp), 1.30 (ddd, 1H, CH2-camp), 1.17 (ddd, 1H, CH2-camp),
0.94 (s, 3H, CH3-anti), 0.71 (s, 3H, CH3-syn). 13C NMR (CDCl3):
δ 166.7 (Cpyr), 139.0 (Cpyr), 138.3 (Car), 137.0 (CHvinyl), 129.2
(CHar), 127.8 (Car), 126.8 (CHar), 125.9 (CHar), 125.2 (CHar),
122.2 (CHpyr), 114.5 (CH2-vinyl), 61.0 (Ccamp), 55.4 (CH2N), 50.7
(Ccamp), 47.8 (CHcamp), 34.3 (CH2-camp), 28.3 (CH2-camp), 21.0
(CH3-syn), 19.7 (CH3-anti), 11.3 (H3-camp). Anal. Calcd for
Ru(1)-N(1)
Ru(1)-O(1)
Ru(1)-Carene(mean)
N(1)-Ru(1)-O(1)
O(1)-Ru(1)-P(1)
N(1)-Ru(1)-P(1)
85.2(2)
94.0(1)
101.1(2)
89.2(2)
90.4(1)
99.4(1)
88.8(2)
88.6(1)
102.2(1)
N(1)-N(2)-C(9)-C(3)
C(1)-C(7)-C(8)-P(1)
22.9(9)
47.1(7)
21.3(10)
-45.1(8)
2.0(8)
-46.4(7)
C
20H24N2: C, 82.1; H, 8.3; N, 9.6. Found: C, 80.2; H, 8.2; N,
9.2.
Syn th esis of 2-[3-(2-(Dip h en ylp h osp h a n y)eth yl)ben -
sion (75 mmol) in DMF (150 mL) was cautiously added
camphorpyrazole (1;23 26 g, 68 mmol) portionwise at 0 °C. The
mixture was subsequently stirred for 3 h at 60 °C. 3-Bro-
mobenzyl bromide (17 g, 68 mmol) was then added and the
solution heated at 60 °C for 20 h. After evaporation of the
volatile material, the product was purified by flash chroma-
tography (hexane/Et2O 5/1), affording bromocamphorpyrazole
zyl]-7,8,8-tr im eth yl-4,5,6,7-tetr a h yd r o-2H-4,7-m eth a n oin -
d a zole (4). The styrene derivative 3 (3.8 g, 13 mmol) and
AIBN (64 mg, 0.4 mmol) were dissolved in Et2O (15 mL). The
solution was degassed with three freeze-pump-thaw cycles,
and HPPh2 (2.9 g, 15.6 mmol, 1.1 equiv) was added. The
mixture was irradiated (Hg low-pressure lamp) in a sealed
Schlenk flask for 38 h. After evaporation of the volatiles in
vacuo, the product was purified by flash chromatography on
silica gel (hexane/ethyl acetate 5/1) to afford the phosphino-
pyrazole PArN* (4; 3.9 g, 63% yield). 1H NMR (CDCl3): δ 7.43
1
3
(2; 13.5 g, 58% yield). H NMR (CDCl3): δ 7.32 (ddd, J H-H
)
4
4
7.7 Hz, J H-H ) 1.1 Hz, and J H-H ) 0.7 Hz, 1H, CHar), 7.15
(dd, 4J H-H ) 0.7 Hz, 1H, CHar), 7.12 (dd, 1H, CHar), 6.98 (ddd,
2
1H, CHar), 6.88 (s, 1H, CHpyr), 5.18 (dd, J H-H ) 16.0 Hz, 2H,
CH2N), 2.73 (d, J H-H ) 4.0 Hz, 1H, CHcamp), 2.04 (m, 1H,
3
3
(m, 4H, CHPh), 7.34 (m, 6H, CHPh), 7.21 (dd, J H-H ) 7.7 Hz
3
CH2-camp), 1.82 (ddd, 1H, CH2-camp), 1.29 (s, 3H, CH3-camp), 1.28
(m, 1H, CH2-camp), 1.14 (m, 1H, CH2-camp), 0.93 (s, 3H, CH3-anti),
0.68 (s, 3H, CH3-syn). 13C NMR (CDCl3): δ 167.7 (Cpyr), 141.7
(Cpyr), 131.5 (CHar), 131.1 (CHar), 130.9 (CHar), 128.6 (Car), 126.4
(CHar), 123.7 (CBr), 122.8 (CHpyr), 61.6 (Ccamp), 55.4 (CH2N),
51.3 (Ccamp), 48.3 (CHcamp), 34.8 (CH2-camp), 28.8 (CH2-camp), 21.5
(CH3-syn), 20.2 (CH3-anti), 11.7 (CH3-camp). Anal. Calcd for
18H21BrN2: C, 62.6; H, 6.1; N, 8.1. Found: C, 62.8; H, 6.1;
N, 8.0.
Syn th esis of 7,8,8-Tr im eth yl-2-(3-vin ylben zyl)-4,5,6,7-
tetr a h yd r o-2H-4,7-m eth a n oin d a zole (3). The bromoarene
2 (5.5 g, 16 mmol), Bu3Sn(CHdCH2) (5.3 g, 16.7 mmol), and
Pd(PPh3)4 (370 mg, 0.32 mmol) were dissolved in toluene (80
mL) and heated at 100 °C for 16 h. After solvent removal in
vacuo, the product was purified by flash chromatography
and J H-H ) 7.4 Hz, 1H, CHar), 7.06 (d, 1H, CHar), 6.95 (d, 1H,
2
CHar), 6.91 (m, 1H, CHar), 6.88 (s, 1H, CHpyr), 5.17 (dd, J H-H
3
) 16.0 Hz, 2H, CH2N), 2.73 (d, J H-H ) 4.0 Hz, 1H, CHcamp),
2.68 (m, 2H, CH2CH2P), 2.30 (m, 2H, CH2CH2P), 2.05 (m, 1H,
CH2-camp), 1.83 (m, 1H, CH2-camp), 1.31 (s, 3H, CH3-camp), 1.30
(m, 1H, CH2-camp), 1.16 (m, 1H, CH2-camp), 0.95 (s, 3H, CH3-anti),
0.67 (s, 3H, CH3-syn). 13C NMR (CDCl3): δ 166.7 (Cpyr), 140.7
(Cpyr), 133.5 (CHPh), 133.3 (CHPh), 129.3 (CHPh), 129.2 (CHar),
128.1 (CHar), 127.5 (CHar), 127.8 (Car), 125.5 (CHar), 122.7 (Car),
122.4 (CHpyr), 61.3 (Ccamp), 55.8 (CH2N), 51.0 (Ccamp), 48.1
(CHcamp), 34.6 (CH2-camp), 32.9 (CH2CH2P), 30.6 (CH2CH2P),
28.6 (CH2-camp), 21.3 (CH3-syn), 19.9 (CH3-anti), 11.5 (CH3-camp).
31P NMR (acetone-d6): δ -16.5 ppm. Mass (FAB): m/z 478.8
(L). Anal. Calcd for C32H35N2P: C, 80.3; H, 7.4; N, 5.9. Found:
C, 79.2; H, 7.7; N, 5.8.
C

1568 Organometallics, Vol. 18, No. 8, 1999
Notes
2
Syn th esis of [(η6-C6H5CO2Et)Ru {η1-(P Ar N*)}Cl2] (5).
The dimer [(η6-C6H5CO2Et)RuCl2]2 (2.35 g, 3.7 mmol) was
suspended in CH2Cl2 (25 mL), and phosphino-pyrazole 4 (3.5
g, 7.3 mmol) was added. The mixture was stirred for 30 min
at room temperature. The volume was reduced to 10 mL and
the product precipitated with hexane to afford [(η6-C6H5CO2-
Et)Ru{η1-(PArN*)}Cl2] (5: 5.6 g, 96% yield). 1H NMR
(CDCl3): δ 7.88-7.82 (m, 4H, CHPh), 7.52-7.41 (m, 6H, CHPh),
(CHar), 51.4 (CH2N), 47.9 (CHcamp), 44.5 (d, J C-P ) 33.0 Hz,
CH2CH2P), 34.5 (CH2-camp), 28.6 (d, 3J C-P ) 5.5 Hz, CH2CH2P),
28.5 (CH2-camp), 21.4 (CH3-syn), 19.8 (CH3-anti), 11.5 (CH3-camp);
31P NMR (CDCl3) δ 46.9 ppm; mass (FAB) m/z 650.9 (Ru-
(PArN*)Cl2), 614.9 (Ru(PArN*)Cl), 580.0 (Ru(PArN*)), 495.1
(P(O)ArN*), 479.5 (PArN*) Anal. Calcd for C32H35Cl2N2PRu:
C, 59.1; H, 5.4; N, 4.3. Found: C, 56.7; H, 5.4; N, 3.9.
Syn th esis of [Ru (η6:η1:η1-(P Ar N*)(OH2)](CF 3SO3)2 (7a
or 7b). The complex 6a or 6b (210 mg, 0.32 mmol) and TlCF3-
SO3 (285 mg, 0.81 mmol) was dissolved in THF (5 mL). The
mixture was stirred for 24 h, filtered on Celite, and evaporated
to dryness; then the solid was dissolved in water, and after
evaporation, 7a or 7b was obtained (260 mg, 0.29 mmol, 91%
yield). Crystals of (R,RP,SRu)-7a and (R,SP,RRu)-7b were ob-
tained independently by slow evaporation of a CHCl3 solution.
7a : 1H NMR (CDCl3) δ 7.67 (m, 2H, CHPh), 7.52 (m, 4H, CHPh),
7.42 (m, 4H, CHPh), 6.99 (s, 1H, CHpyr), 6.47 (s, 1H, CHar), 6.35
(dd, 3J H-H ) 6.1 Hz, 3J H-H ) 6.1 Hz, 1H, CHar), 6.14 (dd, 4J H-H
) 2.7 Hz, 1H, CHar), 5.21 (m, 1H, CH2N and 1H, CHar), 5.05
3
3
7.04 (dd, J H-H ) 7.7 Hz, J H-H ) 7.7 Hz, 1H, CHar), 6.85 (d,
1H, CHar), 6.80 (d, 1H, CHar), 6.79 (s, 1H, CHpyr), 6.70 (s, 1H,
3
CHar), 6.33 (d, J H-H ) 6.3 Hz, 2H, CHester), 5.44 (m, 1H,
CHester), 5.08 (s, 2H, CH2N), 5.06 (m, 2H, CHester), 4.28 (q, 3J H-H
) 7.0 Hz, 2H, CH2-ester), 2.83 (m, 2H, CH2CH2P), 2.68 (d, 3J H-H
) 3.7 Hz, 1H, CHcamp), 2.36 (m, 2H, CH2CH2P), 2.00 (m, 1H,
CH2-camp), 1.78 (m, 1H, CH2-camp), 1.33 (t, 3H, CH3-ester), 1.24
(s, 3H, CH3-camp), 1.24 (m, 1H, CH2-camp), 1.08 (m, 1H,
CH2-camp), 0.89 (s, 3H, CH3-anti), 0.60 (s, 3H, CH3-syn). 13C NMR
(CDCl3): δ 166.0 (CO), 163.9 (Cpyr), 141.9 (Cpyr), 138.1 (CPh),
133-128 (CAr, CHar and CHPh), 121.7 (CHpyr), 94.7 (CHester),
89.5 (CHester), 86.2 (Cester), 84.7 (CHester), 62.4 (CH2-ester), 60.5
(Ccamp), 55.0 (CH2N), 50.2 (Ccamp), 47.3 (CHcamp), 33.8 (CH2-camp),
(d, 2J H-H ) 14.7 Hz, 1H, CH2N), 3.72 (m, 1H, CH2CH2P), 3.50
(m, 1H, CH2CH2P), 2.80 (m, 1H, CH2CH2P), 2.68 (d, J H-H
3
)
3
29.6 (d, J C-P ) 5.5 Hz, CH2CH2P), 27.8 (CH2-camp), 26.6 (d,
3.7 Hz, 1H, CHcamp), 2.55 (m, 1H, CH2CH2P), 1.92 (m, 1H,
CH2-camp), 1.44 (m, 1H, CH2-camp), 1.34 (s, 3H, CH3-camp), 1.25
(m, 1H, CH2-camp), 1.05 (m, 1H, CH2-camp), 0.72 (s, 3H, CH3-anti),
0.40 (s, 3H, CH3-syn); 13C NMR (CDCl3) δ 170.0 (Ccamp), 134.4-
125.7 (Cph and CHPh), 119.2 (CHpyr), 107.1 (CHar), 104.0 (Car),
88.8 (CHar), 84.6 (Car), 85.8 (CHar), 73.8 (CHar), 70.5 (CH2N),
61.5 (Car), 54.4 (CH2CH2P), 49.4 (CH2CH2P), 46.7 (CHcamp), 32.5
(CH2-camp), 27.7 (CH2-camp), 21.2 (CH3-syn), 19.6 (CH3-anti), 12.2
(CH3-camp); 31P NMR (CDCl3) δ 50.4 ppm. 7b: 1H NMR (CDCl3)
δ 7.80-7.63 (m, 4H, CHPh), 7.51 (s, 1H, CHpyr), 7.40-7.37 (m,
6H, CHPh), 5.90 (dd, 3J H-H ) 5.9 Hz, 3J H-H ) 5.9 Hz, 1H, CHar),
5.57 (d, 1H, CHar), 5.32 (system AA′, 2H, CH2N), 5.00 (d, 1H,
CHar), 4.45 (s, 1H, CHar), 3.60-3.30 (m, 2H, CH2CH2P), 2.81
2J C-P ) 27.4 Hz, CH2CH2P), 22.6 (CH3-syn), 20.6 (CH3-anti), 14.5
(CH3-ester), 10.8 (CH3-camp). 31P NMR (CDCl3): δ 23.0 ppm.
Mass (FAB): m/z 800.7 (RuCl2(PArN*)(η6-ester)), 764.7 (RuCl-
(PArN*)(η6-ester), 730.7 (Ru(PArN*)(η6-ester)), 649.7 (RuCl2-
(PArN*)), 614.7 (RuCl(PArN*)), 579.7 (Ru(PArN*)), 478.8
(PArN*). Anal. Calcd for C41H45Cl2N2O2PRu: C, 61.5; H, 5.7;
N, 3.5. Found: C, 61.2; H, 6.0; N, 3.3.
Syn th esis of [Ru {η6:η1-(P Ar N*)}Cl2] (6). In a Schlenk
pressure vessel, the piano-stool complex [(η6-C6H5CO2Et)Ru-
{η1-(PArN*)}Cl2] (5; 1.36 g, 1.7 mmol) was dissolved in CH2-
Cl2 (15 mL). After three freeze-thaw-pump cycles, the orange
solution was heated to 120 °C for 24 h and cooled to room
temperature and the product was purified on silica gel (CH2-
Cl2/acetone 5/1) to afford diastereomerically pure (R,RP)-[{η6:
η1-(PArN*)}RuCl2] (6a ) and (R,SP)-[{η6:η1-(PArN*)}RuCl2] (6b)
(0.32 and 0.38 g, 28.9% and 34.3% yields, respectively). 6a :
1H NMR (CDCl3) δ 7.73-7.64 (m, 4H, CHPh), 7.52 (s, 1H,
3
(d, J H-H ) 4.0 Hz, 1H, CHcamp), 2.63-2.50 (m, 2H, CH2CH2P
and 1H, CH2-camp), 2.05 (m, 1H, CH2-camp), 1.83 (m, 1H,
CH2-camp), 1.27 (s, 3H, CH3-camp), 1.25 (m, 1H, CH2-camp), 1.21
(m, 1H, CH2-camp), 0.95 (s, 3H, CH3-anti), 0.71 (s, 3H, CH3-syn);
13C NMR (CDCl3) δ 135-129 (CPh and CHPh), 126.4 (CHpyr),
118.9 (Car), 107.5 (CHar), 89.7 (CHar), 84.6 (Car), 77.9 (CHar),
3
CHpyr), 7.40-7.33 (m, 6H, CHPh), 5.91 (dd, J H-H ) 6.3 Hz,
3J H-H ) 5.5 Hz, 1H, CHar), 5.58 (d, 1H, CHar), 5.39 (d, 2J H-H
)
2
74.2 (CHar), 61.1 (CH2N), 46.8 (CHcamp), 44.5 (d, J C-P ) 33.0
16.9 Hz, 1H, CH2N), 5.26 (d, 1H, CH2N), 5.01 (d, 1H, CHar),
Hz, CH2CH2P), 33.6 (CH2-camp), 32.4 (CH2CH2P), 27.4 (CH2-camp),
21.8 (CH3-syn), 19.7 (CH3-anti), 14.9 (CH3-camp); 31P NMR
(CDCl3) δ 45.9 ppmm; mass (FAB) m/z 728.8 (Ru(PArN*)-
(OTf)), 597.8 (Ru(PArN*)(H2O)), 579.8 (Ru(PArN*)), 494.9
(P(O)ArN*). Anal. Calcd for C34H37F6N2O7PRuS2: C, 45.6; H,
4.2; N, 3.1. Found: C, 45.2; H, 4.3; N, 2.9.
4.46 (s, 1H, CHar), 3.47 (m, 1H, CH2CH2P), 3.40 (m, 1H,
3
CH2CH2P), 2.81 (d, J H-H ) 3.7 Hz, 1H, CHcamp), 2.58 (m, 2H,
CH2CH2P), 2.06 (m, 1H, CH2-camp), 1.85 (m, 1H, CH2-camp), 1.24
(s, 3H, CH3-camp), 1.25 (m, 1H, CH2-camp), 1.12 (m, 1H,
CH2-camp), 0.96 (s, 3H, CH3-anti), 0.71 (s, 3H, CH3-syn); 13C NMR
(CDCl3) δ 168.6 (Cpyr), 134-129 (CAr and CHPh), 125.0 (CHpyr),
112.0 (C), 97.8 (CHar), 86.1 (CHar), 78.8 (CHar), 76.9 (CHar),
51.4 (CH2N), 47.9 (CHcamp), 44.5 (d, 2J C-P ) 33.0 Hz, CH2CH2P),
Ack n ow led gm en t. This work was supported by the
Swiss National Science Foundation and the Stiftung fu¨r
Stipendien auf dem Gebiete der Chemie (Award of an
A. Werner Fellowship to T.R.W., 1994-1999). T.R.W.
thanks Prof. Ludi for his hospitality and Prof. Novartis
for elemental analyses.
3
34.5 (CH2-camp), 28.6 (d, J C-P ) 5.5 Hz, CH2CH2P), 28.5
(CH2-camp), 21.4 (CH3-syn), 19.8 (CH3-anti), 11.5 (CH3-camp); 31P
NMR (CDCl3) δ 46.4 ppm. 6b: 1H NMR (CDCl3) δ 7.8-7.6 (m,
4H, CHPh), 7.51 (s, 1H, CHpyr), 7.40-7.35 (m, 6H, CHPh), 5.97
3
3
(dd, J H-H ) 5.9 Hz, J H-H ) 5.9 Hz, 1H, CHar), 5.75 (d, 1H,
CHar), 5.44 (d, 2J H-H ) 16.9 Hz, 1H, CH2N), 5.24 (d, 1H, CH2N),
4.98 (d, 1H, CHar), 4.25 (s, 1H, CHar), 3.53 (m, 1H, CH2CH2P),
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data, atomic coordinates, anisotropic thermal parameters,
bond lengths, and bond angles of compounds 7a and 7b. This
material is available free of charge via the Internet at
http://pubs.acs.org.
3
3.40 (m, 1H, CH2CH2P), 2.82 (d, J H-H ) 3.7 Hz, 1H, CHcamp),
2.54 (m, 1H, CH2CH2P), 2.50 (m, 1H, CH2CH2P), 2.06 (m, 1H,
CH2-camp), 1.83 (m, 1H, CH2-camp), 1.27 (s, 3H, CH3-camp), 1.25
(m, 1H, CH2-camp), 1.12 (m, 1H, CH2-camp), 0.96 (s, 3H, CH3-anti),
0.62 (s, 3H, CH3-syn); 13C NMR (CDCl3) δ 134-129 (CAr and
CHPh), 124.9 (CHpyr), 97.8 (CHar), 86.1 (CHar), 78.8 (CHar), 76.9
OM980949I