New racemic planar-chiral metalloligands derived from donor-substituted indenes: A synthetic, structural, and catalytic investigation

Article abstract of DOI:10.1021/om700832f

The synthesis and characterization of a new family of (η⁵- indenyl)ML_n complexes (ML_n = Mn(CO)₃, Cp*Ru, or Cp*Fe; Cp* = η⁵-C₅Me ₅) derived from 3-PⁱPr₂-indene, 1-P ⁱPr₂-2-NMe₂-indene (1a[H]), or 1-P(S) ⁱPr₂-2-NMe₂-indene (1b[H]) are described. Lithiation of 1b[H] followed by treatment with BrMn-(CO)₅, 0.25 equiv of [Cp*RuCl]₄, or Cp*Li/FeCl₂ provided the corresponding (η⁵-1b)ML_n complexes (ML_n = Mn(CO)₃, 2a, 96%; Cp*Ru, 2b, 87%; or Cp*Fe, 2c, 55%). Similarly, treatment of 1a[Li] with 0.25 equiv of [Cp*RuCl]₄ or Cp*Li/FeCl₂ provided the corresponding (η⁵-1a) ML_n complexes (ML_n = Cp*Ru, 3b, 74%; or Cp*Fe, 3c, 62%). Whereas combination of 3b and 0.5 equiv of [(COD)RhCl]₂ afforded [(COD)Rh(κ²-P,N-3b)]⁺Cl^- ([4b]⁺Cl^-; 49% isolated yield), under similar conditions 3c was observed to undergo a decomposition reaction resulting in the formation of the zwitterionic complex (COD)Rh(κ²-P,N-1a) (5; COD = η⁴-1,5-cyclooctadiene). Each of 3a-c was observed to react cleanly with [(COD)Rh(THF)₂]⁺BF₄^- (prepared in situ) to give the corresponding [(COD)Rh(κ²-P,N- 3a-c)]⁺BF₄^- complex ([4a-C]⁺BF ^4-; 87%, 96%, and 89% isolated yield, respectively). Whereas lithiation of 3-Pⁱ-Pr₂-indene followed by the addition of BrMn(CO)₅ generated a complex mixture of products, similar reactions employing 0.25 equiv of [Cp*RuCl]₄ or Cp*Li/FeCl₂ afforded 6b or 6c in 98% and 43% yield, respectively. Treatment of 6b with 0.5 equiv of [(COD)RhCl]₂ allowed for the isolation of (COD)RhCl-(κ¹-P-6b) 7 in 96% isolated yield. Each of [4a-C]⁺BF₄^- proved to be an active catalyst for addition of pinacolborane to styrene, with the observed regioselectivity being dependent on the nature of the η⁵- coordinated metal fragment, as well as the solvent employed. Single-crystal X-ray diffraction data for 2a, 2b, 2c, 3b, [4c]⁺BF₄ ^-, and 7 are provided.

Full text of DOI:10.1021/om700832f

6418
Organometallics 2007, 26, 6418-6427
New Racemic Planar-Chiral Metalloligands Derived from
Donor-Substituted Indenes: A Synthetic, Structural, and
Catalytic Investigation
Dominik Wechsler,† Matthew A. Rankin,† Robert McDonald,‡ Michael J. Ferguson,‡
Gabriele Schatte,§ and Mark Stradiotto*,†
Department of Chemistry, Dalhousie UniVersity, Halifax, NoVa Scotia B3H 4J3, Canada, X-Ray
Crystallography Laboratory, Department of Chemistry, UniVersity of Alberta, Edmonton,
Alberta T6G 2G2, Canada, and Saskatchewan Structural Sciences Centre,
UniVersity of Saskatchewan, Saskatoon, SK S7N 5C9, Canada
ReceiVed August 15, 2007
The synthesis and characterization of a new family of (η5-indenyl)MLn complexes (MLn ) Mn(CO)3,
Cp*Ru, or Cp*Fe; Cp* ) η5-C5Me5) derived from 3-PiPr2-indene, 1-PiPr2-2-NMe2-indene (1a[H]), or
1-P(S)iPr2-2-NMe2-indene (1b[H]) are described. Lithiation of 1b[H] followed by treatment with BrMn-
(CO)5, 0.25 equiv of [Cp*RuCl]4, or Cp*Li/FeCl2 provided the corresponding (η5-1b)MLn complexes
(MLn ) Mn(CO)3, 2a, 96%; Cp*Ru, 2b, 87%; or Cp*Fe, 2c, 55%). Similarly, treatment of 1a[Li] with
0.25 equiv of [Cp*RuCl]4 or Cp*Li/FeCl2 provided the corresponding (η5-1a)MLn complexes (MLn )
Cp*Ru, 3b, 74%; or Cp*Fe, 3c, 62%). Whereas combination of 3b and 0.5 equiv of [(COD)RhCl]2
afforded [(COD)Rh(κ2-P,N-3b)]+Cl- ([4b]+Cl-; 49% isolated yield), under similar conditions 3c was
observed to undergo a decomposition reaction resulting in the formation of the zwitterionic complex
(COD)Rh(κ2-P,N-1a) (5; COD ) η4-1,5-cyclooctadiene). Each of 3a-c was observed to react cleanly
-
with [(COD)Rh(THF)2]+BF4- (prepared in situ) to give the corresponding [(COD)Rh(κ2-P,N-3a-c)]+BF4
complex ([4a-c]+BF4 ; 87%, 96%, and 89% isolated yield, respectively). Whereas lithiation of 3-Pi-
-
Pr2-indene followed by the addition of BrMn(CO)5 generated a complex mixture of products, similar
reactions employing 0.25 equiv of [Cp*RuCl]4 or Cp*Li/FeCl2 afforded 6b or 6c in 98% and 43% yield,
respectively. Treatment of 6b with 0.5 equiv of [(COD)RhCl]2 allowed for the isolation of (COD)RhCl-
-
(κ1-P-6b) 7 in 96% isolated yield. Each of [4a-c]+BF4 proved to be an active catalyst for addition of
pinacolborane to styrene, with the observed regioselectivity being dependent on the nature of the η5-
coordinated metal fragment, as well as the solvent employed. Single-crystal X-ray diffraction data for
-
2a, 2b, 2c, 3b, [4c]+BF4 , and 7 are provided.
Scheme 1. Coordination Complexes Derived from
P,N-Substituted Indene Ligands
Introduction
In the quest to identify new classes of metal complexes that
are capable of mediating synthetically useful substrate trans-
formations involving the activation of E-H bonds (E ) main
group fragment),1 we are exploring the coordination chemistry
of various donor-substituted indene ligands, including 1-PR2-
2-NR′2-indenes (1[H], Scheme 1). Thus far, ligands of type 1-
[H] have proven to be remarkably versatile, providing access
to a range of neutral, cationic, and formally zwitterionic κ2-
P,N late metal complexes that exhibit interesting stoichiometric
and catalytic reactivity with E-H bonds.2 Such zwitterionic
complexes are unusual in that the indenide unit functions as an
uncoordinated anionic charge reservoir to counterbalance the
κ2-P,N-coordinated cationic MLn fragment, rather than as a
locale for metal binding.3
Given the unusual coordination chemistry exhibited by 1[H]
in the formation of zwitterionic κ2-P,N complexes, we became
interested in surveying the feasibility of preparing more
conventional η5-indenylmetal derivatives of 1[H]. From a
fundamental perspective, the successful synthesis of analogous
(η5-indenyl)MLn and κ2-P,N-MLn derivatives of 1[H] would
allow for the relative stability of such linkage isomers to be
evaluated. Furthermore, we envisioned that η5-MLn species
derived from 1[H], once resolved, could be employed as a new
class of enantiopure planar-chiral metalloligands (PCMs) for
use in the construction of chiral dinuclear η5/κ2-P,N catalyst
* Corresponding author. Tel.: (902) 494-7190. Fax: (902) 494-1310.
E-mail: mark.stradiotto@dal.ca.
† Dalhousie University.
‡ University of Alberta.
§ University of Saskatchewan.
(1) For selected reviews, see: (a) Beletskaya, I. P.; Moberg, C. Chem.
ReV. 2006, 106, 2320. (b) Alonso, F.; Beletskaya, I. P.; Yus, M. Chem.
ReV. 2004, 104, 3079. (c) Tanaka, M. Top. Curr. Chem. 2004, 232, 25. (d)
Reichl, J. A.; Berry, D. A. AdV. Organomet. Chem. 1999, 43, 197. (e) Han,
L.-B.; Tanaka, M. Chem. Commun. 1999, 395. (f) Beletskaya, I.; Pelter, A.
Tetrahedron 1997, 53, 4957.
10.1021/om700832f CCC: $37.00 © 2007 American Chemical Society
Publication on Web 10/27/2007

Planar-Chiral Metalloligands
Organometallics, Vol. 26, No. 25, 2007 6419
Scheme 2. Synthesis of the (η5-1b)MLn Complexes 2a, 2b,
complexes. While PCMs featuring P,N-donors built upon a
ferrocenyl core have proven to be effective in promoting high
activity and enantioselectivity in a range of metal-mediated
asymmetric transformations,4 the development of alternative
half-sandwich P,N-ligands of this type has received relatively
little attention.5-9 However, comparative studies reported thus
far suggest that such alternative PCMs can, in some catalytic
applications, offer performance that is on par with, and even
superior to,7b,9a,b,d more traditional ferrocenyl-based PCMs. In
this context, we anticipated that the successful preparation of
structurally diverse η5-MLn derivatives of 1[H] would allow
for the facially bound metal MLn fragment in such complexes
to serve as a control element in tuning the steric and electronic
properties of the κ2-P,N-coordinated M′Ln fragment (Scheme
1). Herein, we report the synthesis and characterization of a
new family of (η5-indenyl)MLn complexes (MLn ) Mn(CO)3,
Cp*Ru, or Cp*Fe; Cp* ) η5-C5Me5) derived from 3-PiPr2-
indene, 1-PiPr2-2-NMe2-indene (1a[H]), or 1-P(S)iPr2-2-NMe2-
indene (1b[H]). Also described is the use of the racemic (η5-
1a)MLn species (3a-c) as κ2-P,N-metalloligands toward
[(COD)Rh]+ (COD ) η4-1,5-cyclooctadiene) to give isolable
dinuclear Mn/Rh, Ru/Rh, and Fe/Rh complexes ([4a-c]+BF4-).
The preliminary catalytic studies reported herein employing
and 2ca
a Reagents: (i) 0.125 equiv of S8; (ii) n-BuLi, followed by
BrMn(CO)5 (for 2a), 0.25 equiv of [Cp*RuCl]4 (for 2b), or Cp*Li/
FeCl2 (for 2c).
Results and Discussion
Our initial synthetic efforts have focused on the preparation
of representative PCMs of type (η5-1a)MLn featuring Mn(CO)3,
Cp*Ru, and Cp*Fe metal fragments. In light of our previous
observation that treatment of BrMn(CO)5 with 1a[Li] resulted
in a complex distribution of products,10 an alternative synthetic
strategy starting from the corresponding phosphine sulfide 1b-
[H] was explored (Scheme 2). Lithiation of 1b[H] followed by
treatment with BrMn(CO)5 led to the clean formation of 2a,
which was isolated as an analytically pure solid in 96% yield.11
Using a similar synthetic protocol, the related Ru and Fe
complexes (2b and 2c) were obtained in 87% and 55% isolated
yield, respectively. Data obtained from both NMR spectroscopic
and X-ray crystallographic studies involving 2a-c support the
assignment of these products as (η5-1b)MLn species. An
ORTEP12 diagram for each of 2a, 2b, and 2c is provided in
Figure 1, while X-ray experimental data and selected metrical
parameters for all of the crystallographically characterized
complexes reported herein are collected in Tables 1 and 2,
respectively. While the structural features observed within the
η5-1b ligands of 2a-c do not differ importantly, some signifi-
cant structural differences are observed with respect to the way
in which the Mn(CO)3, Cp*Ru, and Cp*Fe fragments coordinate
to 1b.13 Deviation from ideal η5-coordination is observed in
2a, with progressive lengthening of the Mn-Cind distances noted
as follows: Mn-C1 ≈ Mn-C3 < Mn-C2 < Mn-C3a ≈
Mn-C7a. Whereas a significant distortion from η5-binding is
also observed in the Cp*Fe complex 2c (Fe-C3a ≈ Fe-C7a
> Fe-C1 ≈ Fe-C2 ≈ Fe-C3), the Ru-Cind distances in 2b
are statistically equivalent (ca. 2.23 Å), with the exception of
the contracted Ru-C1 contact (2.181(2) Å).
[4a-c]+BF4 revealed that altering the η5-coordinated metal
-
fragment in such dinuclear catalysts can lead to modest changes
in the regioselectivity observed in the hydroboration of alkenes.
(2) (a) Lundgren, R. J.; Rankin, M. A.; McDonald, R.; Schatte, G.;
Stradiotto, M. Angew. Chem., Int. Ed. 2007, 46, 4732. (b) Wile, B. M.;
McDonald, R.; Ferguson, M. J.; Stradiotto, M. Organometallics 2007, 26,
1069. (c) Cipot, J.; McDonald, R.; Ferguson, M. J.; Schatte, G.; Stradiotto,
M. Organometallics 2007, 26, 594. (d) Cipot, J.; Vogels, C. M.; McDonald,
R.; Westcott, S. A.; Stradiotto, M. Organometallics 2006, 25, 5965. (e)
Wile, B. M.; Burford, R. J.; McDonald, R.; Ferguson, M. J.; Stradiotto, M.
Organometallics 2006, 25, 1028. (f) Rankin, M. A.; McDonald, R.; Ferguson
M. J.; Stradiotto, M. Organometallics 2005, 24, 4981.
(3) For discussions pertaining to the diverse coordination behavior of
indenyl ligands, see: (a) Bradley, C. A.; Lobkovsky, E.; Keresztes, I.; Chirik,
P. J. J. Am. Chem. Soc. 2005, 127, 10291. (b) Bradley, C. A.; Keresztes, I.;
Lobkovsky, E.; Young, V. G.; Chirik, P. J. J. Am. Chem. Soc. 2004, 126,
16937. (c) Zargarian, D. Coord. Chem. ReV. 2002, 233-234, 157. (d)
Stradiotto, M.; McGlinchey, M. J. Coord. Chem. ReV. 2001, 219-221, 311.
(e) Lobanova, I. A.; Zdanovich, V. I. Russ. Chem. ReV. 1988, 57, 967.
(4) For reviews, see: (a) Arraya´s, R. G.; Adrio, J.; Carretero, J. C. Angew.
Chem., Int. Ed. 2006, 45, 7674. (b) Barbaro, P.; Bianchini, C.; Giambastiani,
G.; Parisel, S. L. Coord. Chem. ReV. 2004, 248, 2131. (c) Atkinson, R. C.
J.; Gibson, V. C.; Long, N. J. Chem. Soc. ReV. 2004, 33, 313. (d) Colacot,
T. J. Chem. ReV. 2003, 103, 3101. (e) Dai, L.-X.; Tu, T.; You, S.-L.; Deng,
W.-P.; Hou, X.-L. Acc. Chem. Res. 2003, 36, 659. (f) Togni, A. Angew.
Chem., Int. Ed. Engl. 1996, 35, 1475.
We have reported previously that 2a is transformed into the
P,N-metalloligand 3a (56% isolated yield) upon treatment with
Cl3SiSiCl3 at 85 °C over the course of 14 d.10 In an effort to
identify more convenient routes to 3a, some alternative reduction
(5) Delacroix, O.; Gladysz, J. A. Chem. Commun. 2003, 665.
(6) For selected (arene)Cr-based PCMs, see: (a) Englert, U.; Hu, C.;
Salzer, A.; Alberico, E. Organometallics 2004, 23, 5419. (b) Gibson, S.
E.; Ibrahim, H. Chem. Commun. 2002, 2465. (c) Bolm, C.; Muniz, K. Chem.
Soc. ReV. 1999, 28, 51.
(7) For selected Mn-based PCMs, see: (a) Gavrilov, K. N.; Tsarev, V.
N.; Konkin, S. I.; Loim, N. M.; Petrovskii, P. V.; Kelbyscheva, E. S.;
Korlyukov, A. A.; Antipin, M. Yu.; Davankov, V. A. Tetrahedron:
Asymmetry 2005, 16, 3224. (b) Lee, J. H.; Son, S. U.; Chung, Y. K.
Tetrahedron: Asymmetry 2003, 14, 2109. (c) Son, S. U.; Park, K. H.; Lee,
S. J.; Chung, Y. K.; Sweigart, D. A. Chem. Commun. 2001, 1290. (d) Kudis,
S.; Helmchen, G. Angew. Chem., Int. Ed. 1998, 37, 3047.
(8) For selected Re-based PCMs, see: (a) Bolm, C.; Xiao, L.; Hinter-
mann, L.; Focken, T.; Raabe, G. Organometallics 2004, 23, 2362. (b) Bolm,
C.; Xiao, L.; Kesselgruber, M. Org. Biomol. Chem. 2003, 1, 145.
(9) For selected Ru-based PCMs, see: (a) Carmichael, D.; Goldet, G.;
Klankermayer, J.; Ricard, L.; Seeboth, N.; Stankevicˇ, M. Chem.-Eur. J.
2007, 13, 5492. (b) Liu, D.; Xie, F.; Zhang, W. Tetrahedron Lett. 2007,
48, 585. (c) Abbenhuis, H. C. L.; Burckhardt, U.; Gramlich, V.; Martelletti,
A.; Spenser, J.; Steiner, I.; Togni, A. Organometallics 1996, 15, 1614. (d)
Hayashi, T.; Ohno, A.; Lu, S.; Matsumoto, Y.; Fukuyo, E.; Yanagi, K. J.
Am. Chem. Soc. 1994, 116, 4221.
(10) Cipot, J.; Wechsler, D.; McDonald, R.; Ferguson, M. J.; Stradiotto,
M. Organometallics 2005, 24, 1737.
(11) The synthesis of 2a has been communicated previously: Wechsler,
D.; McDonald, R.; Ferguson, M. J.; Stradiotto, M. Chem. Commun. 2004,
2446.
(12) ORTEP-3 for Windows version 1.074: Farrugia, L. J. J. Appl.
Crystallogr. 1997, 30, 565.
(13) For some related crystallographically characterized Mn, Fe, and Ru
complexes of donor-substituted indenes, see: (a) Thimmaiah, M.; Luck,
R. L.; Fang, S. J. Organomet. Chem. 2007, 692, 1956. (b) Adams, J. J.;
Curnow, O. J.; Fern, G. M. Inorg. Chim. Acta 2006, 359, 3596. (c) Curnow,
O. J.; Fern, G. M.; Hamilton, M. L.; Jenkins, E. M. J. Organomet. Chem.
2004, 689, 1897. (d) Kamigaito, M.; Watanabe, Y.; Ando, T.; Sawamoto,
M. J. Am. Chem. Soc. 2002, 124, 9994. (e) Adams, J. J.; Berry, D. E.;
Browning, J.; Burth, D.; Curnow, O. J. J. Organomet. Chem. 1999, 580,
245. (f) Stradiotto, M.; Kozak, C.; McGlinchey, M. J. J. Organomet. Chem.
1998, 564, 101. (g) Plenio, H.; Burth, D. Organometallics 1996, 15, 1151.
(h) Plenio, H.; Burth, D. Z. Anorg. Allg. Chem. 1996, 622, 225. (i) Reference
10 herein.

6420 Organometallics, Vol. 26, No. 25, 2007
Wechsler et al.
Figure 1. ORTEP diagrams for 2a, 2b, and 2c, shown with 50% displacement ellipsoids and with the atomic numbering scheme depicted.
Selected hydrogen atoms have been omitted for clarity.
Table 1. Crystallographic Data for 2a, 2b, 2c, 3b, [4c]+BF4-, and 7
2a
C20H25Mn1N1O3P1S1 C27H40Ru1N1P1S1 C27H40Fe1N1P1S1
445.38 542.70 497.48
2b
2c
3b
[4c]+BF4
7
-
empirical formula
formula weight
crystal dimensions
crystal system
space group
a (Å)
C27H40Ru1N1P1
510.64
C35H52B1F4Fe1N1P1Rh1 C33H47Cl1P1Rh1Ru1
763.32
714.11
0.46 × 0.39 × 0.32 0.35 × 0.32 × 0.11 0.60 × 0.29 × 0.29 0.51 × 0.47 × 0.20 0.15 × 0.10 × 0.10
0.05 × 0.05 × 0.05
monoclinic
P21/c
monoclinic
P21/c
monoclinic
P21/c
monoclinic
P21/c
orthorhombic
P212121
11.4520(3)
14.8950(4)
19.7890(5)
90
triclinic
P1h
9.688(2)
15.570(4)
13.898(3)
90
15.0636(7)
10.1395(5)
17.1950(8)
90
11.599(1)
9.824(1)
22.447(2)
90
11.5111(8)
9.8759(7)
22.979(2)
90
8.2280(7)
18.737(2)
20.574(2)
79.373(5)
88.354(4)
79.595(5)
3066.2(5)
4
b (Å)
c (Å)
R (deg)
â (deg)
91.494(4)
90
96.1692(8)
90
102.364(2)
90
103.242(1)
90
90
90
γ (deg)
V (Å3)
2095.8(8)
4
2611.1(2)
4
2498.7(4)
4
2542.9(3)
4
3375.6(2)
4
Z
F
calcd (g cm-3
)
1.412
1.381
1.322
1.334
1.502
1.547
1.191
52.74
µ (mm-1
)
0.825
0.756
0.766
0.693
1.014
2θ limit (deg)
52.78
52.76
52.82
52.80
54.94
-12 e h e 12
-19 e k e 19
-17 e l e 17
16 327
-18 e h e 18
-12 e k e 12
-21 e l e 21
17 659
-14 e h e 14
-12 e k e 12
-28 e l e 28
18 496
-14 e h e 14
-12 e k e 12
-28 e l e 28
19 661
-14 e h e 14
-19 e k e 19
-25 e l e 25
7698
-10 e h e 10
-23 e k e 23
-25 e l e 24
20 189
total data collected
independent
reflections
Rint
4273
5333
5112
5200
7698
12 349
0.0252
3966
0.0290
4696
0.0225
4506
0.0231
4761
N/A
6635
0.0708
9540
observed
reflections
range of
0.7781-0.7027
4273/0/244
0.0273
0.9214-0.7777
0.8083-0.6563
0.8738-0.7189
0.9054-0.8628
0.9429-0.9429
transmission
data/restraints/
parameters
5333/0/285
5112/0/285
5200/0/276
7698/0/408
12 349/838/785
R1 [Fo2 g 2σ(Fo )]
0.0244
0.0657
1.071
0.0314
0.0865
1.032
0.0223
0.0610
1.043
0.0441
0.0979
1.066
0.0603
0.1344
1.035
2
wR2 [Fo2 g -3σ( Fo )] 0.0764
2
GOF
1.043
protocols were surveyed (Scheme 3). Whereas the use of Raney
Ni resulted in the rapid decomposition of 2a, Cp2ZrHCl proved
to be a more useful reducing agent for the conversion of 2a to
3a at ambient temperatures, thereby allowing for the isolation
of 3a in 83% yield. However, in optimizing the synthetic
protocol, a total of 6 equiv of Cp2ZrHCl delivered over the
course of 42 h was found to be necessary to effect the complete
conversion of 2a to 3a at ambient temperature, and efforts to
accelerate the reduction by heating of the reaction mixture
(60 °C) resulted in the formation of multiple phosphorus-
containing byproducts. While the clean reduction of 2b to 3b
(31P NMR) was also achieved by use of excess Cp2ZrHCl over
the course of 15 d at ambient temperature, a mixture of products
(including 1a[H]) was observed in the attempted reduction of
2c with Cp2ZrHCl under similar conditions. However, in contrast
to the complex reactivity observed between 1a[Li] and BrMn-
(CO)5,10 compounds 3b and 3c were prepared conveniently from
1a[Li] and 0.25 equiv of [Cp*RuCl]4 or Cp*Li/FeCl2 in 74%
and 62% isolated yield, respectively. Solution NMR spectro-
scopic data support fully the formulation of 3b and 3c as facially
bound (η5-1a)MLn complexes, including the observation of
relatively low-frequency 31P NMR chemical shifts in comparison
to related κ2-P,N complexes of 1a,2 and the observation of one
1H NMR and one 13C NMR resonance attributable to the NMe2
unit in 3b or 3c, resulting from a rotation/inversion process
involving the uncoordinated N-donor fragment that is rapid on
the NMR time scale at 300 K. Furthermore, the connectivity in
3b was confirmed by use of single-crystal X-ray diffraction
methods; an ORTEP12 diagram for 3b is provided in Figure 2.
The overall structural characteristics of 3b compare well with
those found in 3a,10 and the related phosphine sulfide 2b (vide
supra). We have reported previously on the reactivity of Cp*Ru-
(κ2-P,N-1a), a formally zwitterionic linkage isomer of 3b that
rearranges rapidly to a hydridocarbene complex via double

Planar-Chiral Metalloligands
Organometallics, Vol. 26, No. 25, 2007 6421
Table 2. Selected Interatomic Distances (Å) for 2a, 2b, 2c, 3a, 3b, [4c]+BF4-, and 7
- b
2a
2b
2c
3aa
3b
[4c]+BF4
7c
7d
P-S
1.9575(6)
1.828(1)
1.417(2)
1.415(2)
1.460(2)
1.466(2)
1.429(2)
1.370(2)
1.416(3)
1.356(3)
1.432(2)
1.429(2)
1.431(2)
2.138(2)
2.158(1)
2.131(2)
2.203(2)
2.190(2)
1.9651(7)
1.808(2)
1.432(3)
1.420(3)
1.457(3)
1.455(3)
1.433(3)
1.358(3)
1.429(3)
1.351(3)
1.426(3)
1.424(3)
1.446(3)
2.181(2)
2.225(2)
2.228(2)
2.229(2)
2.222(2)
1.9659(6)
1.813(2)
1.434(2)
1.421(2)
1.452(2)
1.458(2)
1.434(2)
1.362(2)
1.423(3)
1.358(3)
1.432(2)
1.425(2)
1.440(2)
2.059(2)
2.068(2)
2.063(2)
2.106(2)
2.118(2)
P-C3
1.837(2)
1.377(2)
1.428(2)
1.454(2)
1.456(2)
1.433(2)
1.360(2)
1.421(3)
1.361(3)
1.423(2)
1.432(2)
1.430(2)
2.135(2)
2.238(2)
2.181(2)
2.192(2)
2.170(2)
1.824(2)
1.428(2)
1.430(2)
1.447(2)
1.452(2)
1.432(2)
1.360(3)
1.426(3)
1.359(3)
1.432(2)
1.429(2)
1.444(2)
2.189(2)
2.204(2)
2.206(2)
2.217(2)
2.228(2)
1.802(5)
1.460(6)
1.433(5)
1.447(6)
1.449(6)
1.428(6)
1.364(8)
1.425(9)
1.362(8)
1.419(7)
1.425(7)
1.463(7)
2.056(5)
2.058(5)
2.078(5)
2.134(4)
2.121(5)
2.350(1)
2.186(3)
2.229(5)
2.270(4)
2.141(5)
2.148(5)
1.807(6)
1.822(6)
N-C2
C1-C2
C2-C3
C3-C3a
C3a-C4
C4-C5
C5-C6
C6-C7
C7-C7a
C1-C7a
C3a-C7a
M-C1
1.410(9)
1.444(9)
1.471(8)
1.437(9)
1.36(1)
1.405(9)
1.444(8)
1.453(8)
1.426(9)
1.373(9)
1.42(1)
1.44(1)
1.34(1)
1.36(1)
1.426(9)
1.433(9)
1.423(9)
2.186(6)
2.198(6)
2.252(6)
2.259(6)
2.224(6)
2.339(2)
2.373(2)
2.218(7)
2.251(7)
2.116(6)
2.143(6)
1.430(9)
1.422(9)
1.455(8)
2.185(6)
2.202(6)
2.243(6)
2.243(6)
2.221(6)
2.351(2)
2.380(2)
2.198(7)
2.215(7)
2.118(6)
2.148(6)
M-C2
M-C3
M-C3a
M-C7a
Rh-P
Rh-N or Cl
e
Rh-Calkene1
Rh-Calkene2
Rh-Calkene3
Rh-Calkene4
e
f
f
a Data from ref 10 herein included for comparison purposes. b The Rh‚‚‚Fe distance in the final refined structure is 4.24 Å. c ,dWithin the first and second
independent molecules of 7, respectively. e The Rh-cyclooctadiene distances trans to phosphorus. f The Rh-cyclooctadiene distances trans to nitrogen or
chloride.
Scheme 3. Synthesis of Complexes 3a, 3b, and 3ca
In contrast to the differing reactivity patterns observed
between 3b and 3c with [(COD)RhCl]2, each of 3a-c was
-
observed to react cleanly with [(COD)Rh(THF)2]+BF4 (pre-
pared in situ) to give the corresponding [(COD)Rh(κ2-P,N-3a-
c)]+BF4- complex ([4a-c]+BF4-; 87%, 96%, and 89% isolated
yield, respectively; Scheme 5). The observation of a single
downfield-shifted 31P NMR resonance (versus 3a-c) that
exhibits coupling to Rh provided support for the existence of a
Rh-P linkage in [4a-c]+BF4-. In addition, while a single H
1
a Reagents: (i) 1.4 equiv of Cl3SiSiCl3, 85 °C, 14 d or 6 equiv of
Cp2ZrHCl, 24 °C, 42 h (for 2a); 6 equiv of Cp2ZrHCl, 24 °C, 15 d
(for 2b); (ii) 0.25 equiv of [Cp*RuCl]4 (for 3b) or Cp*Li/FeCl2 (for
3c).
NMR resonance and a single 13C NMR resonance attributable
to the NMe2 unit is observed for each of 3a-c (vide supra),
coordination of the amino moiety to Rh in [4a-c]+BF4- results
in the observation of two distinct NMe signals in each of the
1H NMR and 13C NMR spectra, in keeping with the C1-
geminal C-H bond activation.2f In monitoring the stability of
3b in solution over the course of 96 h at 65 °C, no evidence for
the rearrangement of 3b to Cp*Ru(κ2-P,N-1a), or the derived
hydridocarbene, was observed (31P NMR).
symmetric nature of these dinuclear complexes. For [4c]+BF4
,
-
the connectivity was confirmed by use of X-ray diffraction
techniques; an ORTEP12 diagram for [4c]+BF4- is provided in
Figure 2. The structural features observed in the 1a fragment
Having established viable synthetic routes to 3a-c, we then
proceeded to examine the Rh coordination chemistry of these
racemic PCMs. In preliminary studies involving [(COD)RhCl]2,
divergent reactivity behavior was observed for the structurally
related Ru (3b) and Fe (3c) metalloligands (Scheme 4).
Treatment of 3b with 0.5 equiv of [(COD)RhCl]2 in THF
resulted in the formation of a yellow precipitate, which in turn
was isolated and identified as [(COD)Rh(κ2-P,N-3b)]+Cl-
([4b]+Cl-; 49% isolated yield). In contrast, under similar
conditions, 3c was transformed cleanly into the known zwitte-
rionic Rh species, 5.2c The apparent ability of 3c to serve as a
transfer agent for the anionic 1a fragment, when placed in the
context of the facile rac/meso isomerization of (3-PPh2-η5-
C9H6)2Fe at ambient temperature in THF solution that has been
reported by Curnow and co-workers,13c suggests that such
Cp*Fe-based metalloligands may be less well-suited for some
catalytic applications. However, a report by Fang and co-
workers,13a in which resolved Cp*Fe(4-PR2-η5-C9H6) complexes
are shown to resist racemization, highlights that the substitution
pattern in such donor-substituted η5-indenyl species can influ-
ence the overall stability of the metalloligand architecture.
of [4c]+BF4 mirror those found within the Ru-metalloligand
-
3b, with the exception of a modest shortening of the P-C3
distance and a lengthening of the N-C2 distance in [4c]+BF4
.
-
As was noted in 2c, the Cp*Fe unit is not bound in a
-
symmetrical fashion to the C5-ring of the 1a unit in [4c]+BF4
,
and instead exhibits a tendency toward η3-coordination. The
interatomic distances found within the Rh coordination sphere
-
of [4c]+BF4 are strikingly similar to those observed in the
related mononuclear complex [(COD)Rh(κ2-3-PiPr2-2-NMe2-
- 2c
indene)]+BF4
,
including the observation of Rh-alkene
distances trans to P that are significantly longer than those trans
to N, in keeping with established structural trends in coordination
chemistry. Whereas the restricted conformational flexibility
associated with the P,N chelate in [4c]+BF4- holds the Cp*Fe
and [(COD)Rh]+ fragments in relatively close proximity, the
Rh‚‚‚Fe distance (4.24 Å) precludes any significant metal-metal
bonding interactions.
In light of the increasing utility of bulky monodentate
phosphine ligands in asymmetric catalysis,14 we sought to extend
our synthetic efforts to the preparation of η5-MLn derivatives

6422 Organometallics, Vol. 26, No. 25, 2007
Wechsler et al.
Figure 2. ORTEP diagrams for 3b, [4c]+BF4-, and 7, shown with 50% displacement ellipsoids and with the atomic numbering scheme
depicted. Selected hydrogen atoms, as well as the tetrafluoroborate anion in [4c]+BF4-, have been omitted for clarity. Only one of the two
crystallographically independent molecules of 7 is shown.
Scheme 4. Divergent Reactivity of 3b and 3c with
[(COD)RhCl]2
Scheme 6. Synthesis of the Metalloligands 6b,c and the
Dinuclear Ru/Rh Complex 7a
a Reagents: (i) n-BuLi, followed by 0.25 equiv of [Cp*RuCl]4 (for
6b) or Cp*Li/FeCl2 (for 6c); (ii) 0.5 equiv of [(COD)RhCl]2.
were characterized spectroscopically, and, in the case of 7, data
from crystallographic studies provided confirmation of the
atomic connectivity; an ORTEP12 diagram for 7 is provided in
Figure 2. The metrical features found in 7 can be compared to
those of 2b, 3b, and the related complex (COD)RhCl(3-PiPr2-
indene).15
-
Scheme 5. Synthesis of the [(K2-P,N-3a-c)Rh(COD)]+BF4
-
Complexes ([4a-c]+BF4
)
The addition of pinacolborane (HBpin) to styrene mediated
by [4a-c]+BF4 was chosen as a test reaction with which to
-
survey the potential influence of the η5-coordinated organome-
tallic moiety on the catalytic properties of the associated (κ2-
P,N)Rh fragment in these dinuclear complexes.16-18 As well
as representing a widely employed chemical transformation that
provides access to organoboron synthons, metal-catalyzed alkene
of 3-PiPr2-indene.15 Lithiation of 3-PiPr2-indene followed by the
addition of BrMn(CO)5 generated a complex mixture of
products, from which the desired complex (3-PiPr2-η5-C9H6)-
Mn(CO)3 (6a) could not be isolated. However, similar reactions
employing 0.25 equiv of [Cp*RuCl]4 or Cp*Li/FeCl2 in place
of BrMn(CO)5 afforded 6b or 6c in 98% and 43% yield,
respectively (Scheme 6). The ability of 6b to function as a
monophosphine ligand was demonstrated upon treatment with
0.5 equiv of [(COD)RhCl]2, thereby allowing for the isolation
of (COD)RhCl(κ1-P-6b) 7 in 96% yield. Each of 6b,c and 7
(16) For selected reviews pertaining to alkene hydroboration, see: (a)
Carroll, A.-M.; O’Sullivan, T. P.; Guiry, P. J. AdV. Synth. Catal. 2005,
347, 609. (b) Crudden, C. M.; Edwards, D. Eur. J. Org. Chem. 2003, 4695.
(c) Reference 1f herein.
(17) Whereas the catecholborane (HBcat) has traditionally been employed
in such hydroboration reactivity surveys, HBpin was chosen specifically
for the studies herein because HBpin is significantly more stable to air and
nucleophiles than is HBcat, and the greater steric bulk of HBpin provides
an increased challenge in terms of attaining branched selectivity. For further
details, see: (a) Crudden, C. M.; Hleba, Y. B.; Chen, A. C. J. Am. Chem.
Soc. 2004, 126, 9200. (b) Reference 16b herein.
(14) For selected reviews, see: (a) Corbet, J.-P.; Mignani, G. Chem. ReV.
2006, 106, 2651. (b) de Vries, J. G.; Lefort, L. Chem.-Eur. J. 2006, 12,
4722. (c) Jerphagnon, T.; Renaud, J. L.; Bruneau, C. Tetrahedron:
Asymmetry 2004, 15, 2101. (d) Muci, A. R.; Buchwald, S. L. Top. Curr.
Chem. 2002, 219, 131. (e) Komarov, I. V.; Bo¨rner, A. Angew. Chem., Int.
Ed. 2001, 40, 1197.
(18) For selected reports in which regioselectivity and enantioselectivity
in alkene hydroboration employing HBcat are used in the evaluation of
PCM design, see: (a) Kloetzing, R. J.; Lotz, M.; Knochel, P. Tetrahedron:
Asymmetry 2003, 14, 255. (b) Reetz, M. T.; Beuttenmu¨ller, E. W.; Goddard,
R.; Pasto´, M. Tetrahedron Lett. 1999, 40, 4977. (c) Schnyder, A.;
Hintermann, L.; Togni, A. Angew. Chem., Int. Ed. Engl. 1995, 34, 931. (d)
Togni, A.; Breutel, C.; Schnyder, A.; Spindler, F.; Landert, H.; Tijani, A.
J. Am. Chem. Soc. 1994, 116, 4062. (e) Reference 9c herein.
(15) Cipot, J.; Wechsler, D.; Stradiotto, M.; McDonald, R.; Ferguson,
M. J. Organometallics 2003, 22, 5185.

Planar-Chiral Metalloligands
Organometallics, Vol. 26, No. 25, 2007 6423
tivity displayed by [4a-c]+BF4- is primarily steric or electronic
Table 3. Rhodium-Catalyzed Addition of Pinacolborane to
Styrenea
in origin. However, the observation of divergent selectivity in
-
transformations mediated by [4a-c]+BF4 suggests that the
branched:linearb
introduction of structural changes to the η5-coordinated metal
fragment may provide a systematic way in which to modify
the steric and electronic properties of the κ2-P,N-ligated metal
fragment in these complexes.
entry
catalyst
solvent
(8a:8b)
-
1
2
3
4
5
6
[4a]+BF4-
[4a]+BF4-
[4b]+BF4-
[4b]+BF4-
[4c]+BF4-
[4c]+BF4
THF
DCE
THF
DCE
THF
DCE
62:38
71:29
35:65
56:44
50:50
54:46
Experimental Section
a Conditions: 24 °C; 5.0 mol % catalyst; 24 h; pinacolborane-to-styrene
ratio of 1.2:1; DCE ) 1,2-dichloroethane. In all experiments listed,
>90 % conversion of the styrene starting material was achieved, and no
hydroboration products were observed in control experiments employing
3a-c. b Product ratio on the basis of GC-FID data, rounded to the nearest
percent. In all cases, alternative boron-containing products represented <3
% of the total product distribution.
General Considerations. All manipulations were conducted in
the absence of oxygen and water under an atmosphere of dinitrogen,
either by use of standard Schlenk methods or within an mBraun
glovebox apparatus, utilizing glassware that was oven-dried
(130 °C) and evacuated while hot prior to use. Celite and Florisil
each were oven-dried for 5 d and then evacuated for 24 h prior to
use. The non-deuterated solvents tetrahydrofuran, diethyl ether,
toluene, hexanes, and pentane were deoxygenated and dried by
sparging with dinitrogen gas, followed by passage through a double-
column solvent purification system purchased from mBraun Inc.
Tetrahydrofuran and diethyl ether were purified over two alumina-
packed columns, while toluene, hexanes, and pentane were purified
over one alumina-packed column and one column packed with
copper-Q5 reactant. All solvents used within the glovebox were
stored over activated 4 Å molecular sieves. CD2Cl2 (Cambridge
Isotopes) was degassed by using three repeated freeze-pump-
thaw cycles, dried over CaH2 for 7 days, distilled in vacuo, and
stored over 4 Å molecular sieves for 24 h prior to use. 1,2-
Dichloroethane (Aldrich), C6D6 (Cambridge Isotopes), and pina-
colborane (HBpin) were each degassed by using three repeated
freeze-pump-thaw cycles and then dried over 4 Å molecular
sieves for 24 h prior to use; styrene (Aldrich, containing 10-15
ppm 4-tert-butylcatechol as inhibitor) was degassed in a similar
manner, but was not stored over molecular sieves. Compounds 1a-
[H] (now available commercially from Strem Chemicals Inc.),20a
hydroboration can serve as a prototype for E-H addition
reactions in which product selectivity can be a challenge.16 In
addition to the possible branched and linear regioisomers that
can arise from simple B-H addition (8a and 8b, eq 1),
unsaturated species formed via dehydrogenative borylation, and
products of net diboration, are also observed commonly.
The preliminary results of our alkene hydroboration survey
are collected in Table 3. Notably, each of [4a-c]+BF4- proved
to be an active catalyst for this transformation, with the observed
regioselectivity, albeit modest,19 being dependent on the nature
of the η5-coordinated metal fragment, as well as the solvent
employed. While the Mn/Rh complex [4a]+BF4- demonstrated
selectivity for the branched product 8a in both THF (entry 1)
and 1,2-dichloroethane (entry 2), the related Ru/Rh species
21
1b[H],20b 1a[Li],20a 3-PiPr2-indene,15 and [Cp*RuCl]4 were pre-
pared employing literature procedures, while [(COD)RhCl]2 was
purchased from Strem Chemicals Inc. (Cp* ) C5Me5; COD ) η4-
1,5-cyclooctadiene). Cp2ZrHCl (Cp ) η5-C5H5), BrMn(CO)5, FeCl2,
and AgBF4 were obtained from Aldrich. All of the aforementioned
purchased and prepared solid reagents were dried in vacuo for 24
h prior to use. Otherwise, all other commercial reagents were
obtained from Aldrich (except for 2.9 M n-BuLi in hexanes, Alfa
Aesar) and were used as received. Unless otherwise stated, 1H, 13C,
and 31P NMR characterization data were collected at 300 K on a
Bruker AV-500 spectrometer operating at 500.1, 125.8, and 202.5
MHz (respectively) with chemical shifts reported in parts per million
[4b]+BF4 exhibited linear selectivity in THF (entry 3), but
-
almost no selectivity in 1,2-dichloroethane (entry 4). As well,
the Fe/Rh complex [4c]+BF4- exhibited poor selectivity in both
of these solvents (entries 5 and 6).
Summary and Conclusions
In summary, we have established modular synthetic pathways
to new pentahapto complexes of the donor-substituted indenyl
ligands 3-PiPr2-indenyl, 1a, and 1b. Comparative reactivity
studies featuring three examples of these (η5-1a)MLn complexes
(i.e., MLn ) Mn(CO)3, Cp*Ru, or Cp*Fe; 3a-c) underscored
some important differences in the behavior of such metallo-
ligands. Whereas 3b reacted cleanly with [(COD)RhCl]2 to give
the Ru/Rh species [4b]+Cl-, the congeneric Fe complex 3c
served as a source of 1a, leading to the generation of the
1
downfield of SiMe4 (for H and 13C) or 85% H3PO4 in D2O (for
31P). 1H and 13C NMR chemical shift assignments are made on the
1
1
basis of data obtained from 13C-DEPT, H-1H COSY, H-13C
HSQC, and H-13C HMBC NMR experiments. In some cases,
1
fewer than expected unique 13C NMR resonances were observed,
despite prolonged acquisition times. IR data were collected on a
Bruker VECTOR 22 FT-IR instrument. Elemental analyses were
performed by Canadian Microanalytical Service Ltd., Delta, British
Columbia, Canada.
mononuclear zwitterionic Rh complex 5. In contrast, each of
3a-cwasobservedtoreactcleanlywith[(COD)Rh(THF)2]+BF4
,
-
Synthesis of 2a. A 1.6 M hexanes solution (precooled to
-35 °C) of n-BuLi (0.20 mL, 0.32 mmol) was added dropwise via
syringe to a glass vial containing a magnetically stirred solution
(precooled to -35 °C) of 1b[H] (0.099 g, 0.32 mmol) in toluene
(5 mL) over 2 min, producing a faint yellow solution. The vial
containing the reaction mixture was then sealed with a PTFE-lined
thereby allowing for the isolation of the corresponding planar-
chiral (racemic) dinuclear η5/κ2-P,N catalyst complexes [4a-
c]+BF4- in high isolated yield. The preliminary alkene hydrob-
oration results described herein establish the viability of [4a-
c]+BF4 as catalysts for the addition of B-H bonds to
-
unsaturated substrates, although we are presently unable to
comment as to whether the source of the differing regioselec-
(20) (a) Stradiotto, M.; Cipot, J.; McDonald, R. J. Am. Chem. Soc. 2003,
125, 5618. (b) Wechsler, D.; Myers, A.; McDonald, R.; Ferguson, M. J.;
Stradiotto, M. Inorg. Chem. 2006, 45, 4562.
(21) Fagan, P. J.; Ward, M. D.; Calabrese, J. C. J. Am. Chem. Soc. 1989,
111, 1698.
(19) By comparison, Crudden and co-workers have demonstrated that
[(COD)2Rh]+BF4-/bisphosphine mixtures can provide >96% branched
selectivity. See ref 17a herein.

6424 Organometallics, Vol. 26, No. 25, 2007
Wechsler et al.
cap and left to stir for 1.5 h at ambient temperature; the clean
lithiation of 1b[H] was monitored in situ by the disappearance of
a 31P NMR signal corresponding to 1b[H] and the appearance of a
single new resonance at 54 ppm. A mixture of BrMn(CO)5 (0.089
g, 0.32 mmol) in toluene (5 mL) was then transferred to the reaction
mixture via Pasteur pipet, and the reaction vial was resealed. A
dark solution formed immediately, and after stirring for 3 d the
solution changed to a yellow-orange color and a white precipitate
formed. The reaction mixture was then filtered through Celite and
the supernatant was dried in vacuo, yielding 2a as an analytically
pure, orange solid (0.14 g, 0.31 mmol, 96%). Anal. Calcd for
C20H25PSNO3Mn: C, 53.93; H, 5.66; N, 3.14. Found: C, 53.61;
H, 5.72; N, 3.26. 1H NMR (C6D6): δ 9.42 (d, 3JHH ) 8.0 Hz, 1H,
C4-H or C7-H), 7.06 (d, 3JHH ) 8.1 Hz, 1H, C7-H or C4-H), 6.80-
6.72 (m, 2H, C5-H and C6-H), 4.46 (s, 1H, C1-H), 3.16 (m, 1H,
P(CHMe2)), 2.18 (m, 1H, P(CHMe2)), 2.09 (s, 6H, NMe2), 1.77 (d
of d, 3JPH ) 18.6 Hz, 3JHH ) 6.0 Hz, 3H, P(CHMeMe)), 1.31 (d of
d, 3JPH ) 17.3 Hz, 3JHH ) 5.7 Hz, 3H, P(CHMeMe)), 1.08 (d of d,
-35 °C. The resulting lime-green mixture (A, containing “Cp*FeCl”)
was stirred magnetically for 2 h. A separate vial was charged with
a stir bar, 1b[H] (0.095 g, 0.31 mmol), and THF (2 mL), and the
mixture was cooled to -35 °C, at which point a precooled 2.9 M
hexanes solution of n-BuLi (0.11 mL, 0.31 mmol) was added
dropwise via Eppendorf pipet. The mixture was stirred magnetically
at ambient temperature for 2 h, after which the solvent and other
volatile materials were removed in vacuo. The residue was washed
with hexanes and dried in vacuo. To the remaining solid was added
THF (2 mL), and this mixture (B) was cooled to -35 °C. Mixture
A was also cooled to -35 °C, at which point mixture B was added
slowly to mixture A, giving a burgundy-colored mixture. This
combined reaction mixture was allowed to react for 18 h at ambient
temperature under the influence of magnetic stirring, after which
the reaction mixture was filtered through Celite and the filtrate was
dried in vacuo. The residue was then extracted with pentane (5
mL), and the resulting pentane mixture was filtered through a short
plug of Celite. The filtrate was collected, and the solvent and other
volatile materials were removed in vacuo. Any decamethylferrocene
that was produced during the synthesis was then removed via
sublimation to leave 2c as an analytically pure, purple solid (0.085
g, 0.17 mmol, 55%). Anal. Calcd for C27H40PSNFe: C, 65.18; H,
8.11; N, 2.82. Found: C, 65.07; H, 8.06; N, 2.75. 1H NMR
3
3JPH ) 17.9 Hz, JHH ) 6.8 Hz, 3H, P(CHMeMe)), 1.77 (d of d,
3JPH ) 17.1 Hz, 3JHH ) 6.7 Hz, 3H, P(CHMeMe)). 13C{1H} NMR
(C6D6): δ 223.7 (CO), 138.7 (C2), 129.0 (C4 or C7), 127.1 (C5 or
C6), 126.1 (C6 or C5), 124.7 (C7 or C4), 105.5 (d, J ) 7.3 Hz,
C7a or C3a), 100.0 (d, J ) 7.6 Hz, C3a or C7a), 61.5 (C1), 46.2
(NMe2), 30.7 (m, P(CHMe2)), 28.0 (m, P(CHMe2)), 19.6 (P(CH-
MeMe)), 19.2 (P(CHMeMe)), 18.5 (P(CHMeMe)), 17.2 (P(CH-
MeMe)). 31P{1H} NMR (C6D6): δ 64.4. FTIR (cm-1) ν(CO): 2014,
1945, 1931. Crystals of 2a suitable for single-crystal X-ray
diffraction analysis were grown from diethyl ether at -35 °C.
(C6D6): δ 9.33 (d, 3JHH ) 8.3 Hz, 1H, C7-H), 7.12 (d of d, 3JHH
)
8.3 Hz, J ) 1.1 Hz, 1H, C4-H), 6.96-7.06 (m, 2H, C5-H and C6-
H), 4.26 (s, 1H, C1-H), 3.13 (m, 1H, P(CHMecMed)), 2.34 (s, 6H,
3
NMe2), 2.06 (m, 1H, P(CHMeaMeb)), 1.90 (d of d, JPH ) 18.2
Hz, 3JHH ) 7.1 Hz, 3H, P(CHMecMed)), 1.54 (s, 15H, C5Me5), 1.37
(d of d, 3JPH ) 16.7 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMedMec)), 1.16
(d of d, 3JPH ) 17.3 Hz, 3JHH ) 6.7 Hz, 3H, P(CHMebMea)), 0.63
(d of d, 3JPH ) 16.8 Hz, 3JHH ) 7.1 Hz, 3H, P(CHMeaMeb)). 13C-
{1H} NMR (C6D6): δ 132.5 (C7), 126.8 (C4), 125.0 (C5 or C6),
123.1 (C6 or C5), 118.9 (d, 2JPC ) 8.4 Hz, C2), 89.3 (C3a or C7a),
Synthesis of 2b. A glass vial charged with a stir bar, 1b[H]
(0.28 g, 0.91 mmol), and diethyl ether (2 mL) was cooled to
-35 °C. To the vial was added dropwise a 1.6 M hexanes solution
of n-BuLi (0.57 mL, 0.91 mmol; precooled to -35 °C) via
Eppendorf pipet, and the mixture was stirred for 1 h. The resulting
slurry was cooled to -35 °C, to which a suspension of [Cp*RuCl]4
(0.25 g, 0.23 mmol) in diethyl ether (2 mL) (precooled to -35 °C)
was added slowly. The reaction mixture was stirred for an additional
1.5 h at ambient temperature, and subsequently filtered through a
plug of Celite. The filtrate was collected, and the solvent and other
volatile materials were removed in vacuo to leave 2b as an
analytically pure, dark yellow solid (0.43 g, 0.79 mmol, 87%). Anal.
Calcd for C27H40PSNRu: C, 59.75; H, 7.43; N, 2.58. Found: C,
1
89.2 (C7a or C3a), 78.2 (C5Me5), 63.6 (d, JPC ) 77.2 Hz, C3),
58.8 (d, 3JPC ) 7.0 Hz, C1), 48.2 (NMe2), 30.5 (d, 1JPC ) 50.3 Hz,
1
P(CHMecMed)), 29.5 (d, JPC ) 24.6 Hz, P(CHMeaMeb)), 20.8
(P(CHMeMe)), 17.8 (P(CHMeMe)), 17.4 (P(CHMeMe)), 17.3
(P(CHMeMe)), 10.1 (C5Me5). 31P{1H} NMR (C6D6): δ 65.2.
Crystals of 2c suitable for single-crystal X-ray diffraction analysis
were grown from pentane at -35 °C.
Protocol for the Reduction of 2a to 3a Using Cp2ZrHCl. To
a solution of 2a (0.13 g, 0.29 mmol) in THF (5 mL) was added 3
equiv of Cp2ZrHCl, followed by stirring for 18 h. Analysis of the
reaction mixture (31P NMR) revealed the incomplete conversion
of 2a to 3a. The reaction mixture was filtered through Celite, an
additional 3 equiv of Cp2ZrHCl was added to the fitrate, and the
mixture was stirred magnetically for an additional 24 h. Analysis
of the reaction mixture (31P NMR) at this stage revealed the
quantitative conversion to 3a. The reaction mixture was filtered
through Celite, and the solvent was removed in vacuo. The residue
was taken up in pentane or hexanes (10 mL) and filtered through
Celite, followed by removal of the solvent in vacuo, affording 3a
(0.10 g, 0.24 mmol, 83%).
1
3
59.71; H, 7.49; N, 2.48. H NMR (C6D6): δ 8.40 (d, JHH ) 9.0
Hz, 1H, C7-H or C4-H), 7.13-7.18 (m, 2H, aryl H), 7.05-7.08
(m, 1H, aryl H), 5.23 (s, 1H, C1-H), 3.35 (m, 1H, P(CHMecMed)),
2.76 (s, 6H, NMe2), 2.45 (m, 1H, P(CHMeaMeb)), 1.73 (d of d,
3JPH ) 18.3 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 1.70 (s, 15H,
C5Me5), 1.46 (d of d, 3JPH ) 17.6 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMed-
Mec)), 1.32 (d of d, 3JPH ) 17.1 Hz, 3JHH ) 6.9 Hz, 3H, P(CHMeb-
3
3
Mea)), 1.05 (d of d, JPH ) 16.9 Hz, JHH ) 7.1 Hz, 3H,
P(CHMeaMeb)). 13C{1H} NMR (C6D6): δ 129.3 (aryl CH), 124.0
2
(aryl CH), 123.1 (aryl CH), 122.6 (d, JPC ) 9.3 Hz, C2), 120.6
(aryl CH), 92.1 (d, JPC ) 8.3 Hz, C3a or C7a), 91.8 (d, JPC ) 10.2
Hz, C7a or C3a), 83.5 (C5Me5), 67.8 (d, 1JPC ) 77.2 Hz, C3), 64.7
3
1
(d, JPC ) 7.2 Hz, C1), 49.1 (NMe2), 31.6 (d, JPC ) 50.5 Hz,
P(CHMeaMeb)), 27.8 (d, JPC ) 51.5 Hz, P(CHMecMed)), 19.8
Synthesis of 3b. A glass vial charged with a stir bar, excess
1a[Li] (1.13 mmol), and THF (2 mL) was cooled to -35 °C. A
separate vial charged with [Cp*RuCl]4 (0.24 g, 0.22 mmol) and
diethyl ether (2 mL) was cooled to -35 °C, and subsequently was
added slowly to the solution of 1a[Li]. The resulting mixture was
stirred magnetically at ambient temperature for 18 h. The solvent
and other volatile materials were removed in vacuo, and the residue
was taken up in a mixture of pentane (5 mL) and diethyl ether (2
mL) and passed through a Florisil column and eluted with pentane.
The filtrate was then concentrated and dried in vacuo affording
analytically pure 3b as a yellow solid (0.33 g, 0.65 mmol, 74%).
Anal. Calcd for C27H40PNRu: C, 63.50; H, 7.89; N, 2.74. Found:
C, 63.25; H, 7.99; N, 2.74. 1H NMR (C6D6): δ 7.55 (d, 3JHH ) 8.5
1
(P(CHMeMe)), 17.6 (P(CHMeMe)), 17.6 (P(CHMeMe)), 16.1
(P(CHMeMe)), 9.9 (C5Me5). 31P{1H} NMR (C6D6): δ 65.3. Crystals
of 2b suitable for single-crystal X-ray diffraction analysis were
grown from pentane at -35 °C.
Synthesis of 2c. A vial was charged with a stir bar, Cp*H (0.049
mL, 0.31 mmol), and THF (2 mL). To the vial was added a
precooled (-35 °C) solution of n-BuLi (0.11 mL of a 2.9 M hexanes
solution, 0.31 mmol) via Eppendorf pipet, at which point a white
precipitate formed immediately. The mixture was stirred magneti-
cally at ambient temperature for 2 h and then cooled to -35 °C.
This mixture was then added dropwise to a suspension of FeCl2
(0.039 g, 0.31 mmol) in THF (1.5 mL) that had been precooled to
3
Hz, 1H, C7-H or C4-H), 6.94 (d, JHH ) 8.5 Hz, 1H, C4-H or

Planar-Chiral Metalloligands
Organometallics, Vol. 26, No. 25, 2007 6425
2
C7-H), 6.86-6.81 (m, 2H, C5-H and C6-H), 4.67 (s, 1H, C1-H),
2.58 (s, 6H, NMe2), 2.57-2.43 (m, 2H, P(CHMecMed) and
Cl2): δ 131.2 (d, JPC ) 24.3 Hz, C2), 125.4 (C7 or C4), 125.0
(aryl CH), 124.5 (aryl CH), 123.9 (aryl CH), 106.6 (br s, COD),
101.8 (br s, COD), 96.9 (d, JPC ) 3.9 Hz, C3a or C7a), 88.1 (C7a
3
P(CHMeaMeb)), 1.57 (s, 15H, C5Me5), 1.36 (d of d, JPH ) 11.5
3
1
Hz, JHH ) 7.0 Hz, 3H, P(CHMecMed)), 1.33-1.25 (m, 6H,
or C3a), 84.8 (C5Me5), 76.2 (m, COD), 69.6 (COD), 69.2 (d, JPC
P(CHMeaMeb)), 1.18 (d of d, 3JPH ) 16.0 Hz, 3JHH ) 7.5 Hz, 3H,
P(CHMedMec)). 13C{1H} NMR (C6D6): δ 128.0 (C4 or C7), 127.3
(d, 2JPC ) 6.5 Hz, C2), 124.7 (C7 or C4), 121.9 (C5 or C6), 120.6
(C6 or C5), 94.0 (d, JPC ) 10.1 Hz, C3a or C7a), 91.3 (C7a or
C3a), 82.1 (C5Me5), 70.6 (d, 1JPC ) 31.8 Hz, C3), 63.3 (C1), 46.8
) 52.5 Hz, C3), 61.1 (d, JPC ) 8.8 Hz, C1), 54.8 (br s, NMe2)
3
34.4 (br s, COD), 30.4 (br s, COD), 26.2-26.1 (P(CHMeaMeb)
1
and COD), 25.5 (d, JPC ) 26.0 Hz, P(CHMecMed)), 20.8
2
(P(CHMedMec)), 20.1 (d, JPC ) 4.0 Hz, P(CHMeaMeb)), 19.4 (d,
2JPC ) 3.7 Hz, P(CHMedMec)), 18.2 (P(CHMeaMeb)), 10.1 (C5Me5).
4
1
1
(d, JPC ) 6.7 Hz, NMe2), 24.3 (d, JPC ) 13.1 Hz, P(CHMec-
31P{1H} NMR (CD2Cl2): δ 42.4 (d, JPRh ) 150.6 Hz).
1
2
Synthesis of [4b]+BF4-. To a glass vial containing a magneti-
cally stirred suspension of [(COD)RhCl]2 (0.025 g, 0.050 mmol)
in THF (2 mL) was added a suspension of AgBF4 (0.020 g, 0.10
mmol) in THF (2 mL); a yellow solution was generated immediately
along with a white precipitate. The supernatant solution was
separated from the precipitate by filtration through Celite, and the
solution was transferred to a glass vial containing a magnetically
stirred solution of 3b (0.051 g, 0.10 mmol) in THF (3 mL). The
reaction mixture was stirred for an additional 3 h at ambient
temperature, during which time the solution developed a yellow-
orange coloration. The reaction mixture was then filtered through
a plug of Celite, followed by removal of the solvent and other
Med)), 23.7 (d, JPC ) 13.1 Hz, P(CHMeaMeb)), 23.3 (d, JPC
)
23.1 Hz, P(CHMedMec)), 22.9 (d, 2JPC ) 20.8 Hz, P(CHMeaMeb)),
21.5 (d, 2JPC ) 18.9 Hz, P(CHMeaMeb)), 20.7 (d, 2JPC ) 11.1 Hz,
P(CHMedMec)), 10.8 (C5Me5). 31P{1H} NMR (C6D6): δ -0.3.
Crystals of 3b suitable for single-crystal X-ray diffraction analysis
were grown from pentane at -35 °C.
Synthesis of 3c. A vial charged with a stir bar and a solution of
Cp*FeCl (1.10 mmol) in THF (2 mL) (prepared in a manner
analogous to that described for the synthesis of 2c) was cooled to
-35 °C. To this solution was added slowly a solution of 1a[Li]
(1.10 mmol) and THF (2 mL) (precooled to -35 °C), and the
mixture was stirred magnetically at ambient temperature for 2 h.
The solvent and other volatile materials were removed in vacuo,
and the residue was taken up in pentane (5 mL) followed by
filtration through a short plug of Celite. The filtrate was collected,
and the solvent and other volatile materials were removed in vacuo.
Any decamethylferrocene that was produced during the synthesis
was then removed via sublimation to leave 3c as an analytically
pure, purple solid (0.31 g, 0.68 mmol, 62%). Anal. Calcd for C27H40-
PNFe: C, 69.57; H, 8.66; N, 3.01. Found: C, 69.57; H, 8.50; N,
-
volatiles in vacuo yielding [4b]+BF4 as a orange solid (0.078 g,
0.096 mmol, 96%). Anal. Calcd for C35H52PNRuRhBF4: C, 51.96;
H, 6.48; N, 1.73. Found: C, 51.84; H, 6.45; N, 1.75. H NMR
(CD2Cl2): δ 7.19 (d, JHH ) 8.5 Hz, 1H, C7-H or C4-H), 7.14-
1
3
7.05 (m, 3H, aryl CH), 5.42 (br s, 1H, COD), 5.19 (s, 1H, C1-H),
4.87 (m, 1H, COD), 4.53 (m, 1H, COD), 3.90 (m, 1H, COD), 3.21
(s, 3H, NMe), 2.80 (s, 3H, NMe), 2.75-2.20 (m, 9H, P(CHMec-
3
Med), P(CHMeaMeb), and COD), 2.01 (d of d, JPH ) 18.0 Hz,
1
3
2.96. H NMR (C6D6): δ 7.77 (d, JHH ) 8.4 Hz, 1H, C7-H or
3JHH ) 7.5 Hz, 3H, P(CHMecMed)), 1.95 (m, 1H, COD), 1.63 (d
of d, 3JPH ) 14.0 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMecMed)), 1.59 (s,
3
C4-H), 7.22 (d, JHH ) 8.0 Hz, 1H, C4-H or C7-H), 6.95-7.02
(m, 2H, C5-H and C6-H), 4.24 (s, 1H, C1-H), 2.63 (s, 6H, NMe2),
3
3
15H, C5Me5), 1.19 (d of d, JPH ) 15.0 Hz, JHH ) 7.5 Hz, 3H,
P(CHMeaMeb)), 0.99 (d of d, 3JPH ) 17.0 Hz, 3JHH ) 7.0 Hz, 3H,
P(CHMeaMeb)). 13C{1H} NMR (CD2Cl2): δ 131.1 (d, 2JPC ) 24.3
Hz, C2), 125.5 (C4 or C7), 125.0 (aryl CH), 124.6 (aryl CH), 124.0
(aryl CH), 106.7 (m, COD), 101.7 (m, COD), 97.0 (C3a or C7a),
88.2 (C7a or C3a), 84.9 (C5Me5), 76.1 (d, J ) 12.7 Hz, COD),
69.7 (d, J ) 12.0 Hz, COD), 69.2 (d, 1JPC ) 32.5 Hz, C3), 60.8 (d,
J ) 8.8 Hz, C1), 55.1 (NMe), 54.0 (NMe), 34.4 (COD), 30.4
(COD), 26.2 (d, 1JPC ) 23.0 Hz, P(CHMecMed)), 26.1 (COD), 25.5
2.53-2.62 (m, 2H, P(CHMecMed) and P(CHMeaMeb)), 1.58 (s,
3
3
15H, C5Me5), 1.58 (d of d, JPH ) 10.3 Hz, JHH ) 7.0 Hz, 3H,
P(CHMeaMeb)), 1.30 (d of d, 3JPH ) 13.7 Hz, 3JHH ) 6.9 Hz, 3H,
P(CHMebMea)), 1.19 (d of d, 3JPH ) 11.3 Hz, 3JHH ) 7.4 Hz, 3H,
3
3
P(CHMecMed)), 1.15 (d of d, JPH ) 7.1 Hz, JHH ) 2.6 Hz, 3H,
P(CHMedMec)). 13C{1H} NMR (C6D6): δ 130.1 (C4 or C7), 123.5
2
(C5 or C6), 122.3 (C6 or C5), 120.6 (d, JPC ) 4.4 Hz, C2), 89.8
(d, JPC ) 12.2 Hz, C3a or C7a), 87.8 (C7a or C3a), 76.8 (C5Me5),
1
4
1
63.3 (d, JPC ) 31.1 Hz, C3), 75.7 (C1), 46.3 (d, JPC ) 6.4 Hz,
(d, JPC ) 25.8 Hz, P(CHMeaMeb)), 20.8 (P(CHMecMed)), 20.1
NMe2), 23.6 (d, 1JPC ) 25.7 Hz, P(CHMecMed) or P(CHMecMed)),
(P(CHMeaMeb)), 19.4 (P(CHMecMed)), 18.2 (P(CHMeaMeb)), 10.0
1
1
23.3 (d, JPC ) 13.8 Hz, P(CHMeaMeb) or P(CHMecMed)), 22.9
(C5Me5). 31P{1H} NMR (CD2Cl2): δ 42.5 (d, JPRh ) 150.4 Hz).
1
Synthesis of [4a]+BF4-. A procedure analogous to that described
(d, JPC ) 11.9 Hz, (P(CHMedMec) or P(CHMeaMeb)), 22.7 (d,
2JPC ) 4.0 Hz, P(CHMecMed) or P(CHMecMed)), 21.5 (d, JPC
)
2
-
for the synthesis of [4b]+BF4 was employed, using 3a (0.015 g,
2
0.037 mmol) in THF (1 mL). Complex [4a]+BF4- was isolated as
a dark yellow solid (0.023 g, 0.032 mmol, 87%). Anal. Calcd for
C28H37PNMnO3RhBF4: C, 47.25; H, 5.24; N, 1.97. Found: C,
47.41; H, 5.62; N, 1.83. 1H NMR (CD2Cl2): δ 7.72 (d, 3JHH ) 8.3
Hz, 1H, C7-H or C4-H), 7.49-7.42 (m, 2H, aryl CH), 7.29 (t, 3JHH
) 7.4 Hz, C6-H or C5-H), 6.05 (s, 1H, C1-H), 5.60 (br s, 1H,
COD), 4.94 (br s, 1H, COD), 4.66 (br s, 1H, COD), 3.94 (br s, 1H,
COD), 3.39 (s, 3H, NMe), 2.81 (s, 3H, NMe), 2.81-2.68 (m, 4H,
P(CHMecMed), P(CHMebMea), and COD), 2.47 (m, 1H, COD),
2.39-2.31 (m, 2H, COD), 2.01-1.93 (m, 5H, COD and P(CH-
MecMed)), 1.89-1.85 (m, 4H, P(CHMecMed) and COD), 1.34 (d
of d, 3JPH ) 15.3 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), 1.22 (d
of d, 3JPH ) 16.9 Hz, 3JHH ) 6.9 Hz, 3H, P(CHMeaMed)). 13C{1H}
19.1 Hz, P(CHMebMea)), 20.2 (d, JPC ) 8.0 Hz, P(CHMebMea)),
10.2 (C5Me5). 31P{1H} NMR (C6D6): δ -2.5.
Synthesis of [4b]+Cl-. To a glass vial charged with a stir bar,
3b (0.12 g, 0.24 mmol), and THF (2 mL) was added a solution of
[(COD)RhCl]2 (0.059 g, 0.12 mmol) in THF (4 mL). The mixture
was stirred for 4 h at ambient temperature, and during this time a
precipitate formed. The supernatant was decanted, and the precipi-
tate was washed with THF (5 mL). The residue was then dried in
vacuo, affording analytically pure [4b]+Cl- as a yellow solid (0.088
g, 0.12 mmol, 49%). Anal. Calcd for C35H52PNRuRhCl: C, 55.50;
1
H, 6.93; N, 1.85. Found: C, 55.22; H, 6.77; N, 1.53. H NMR
3
(CD2Cl2): δ 7.17 (d, JHH ) 8.5 Hz, 1H, C7-H or C4-H), 7.12-
7.00 (m, 3H, aryl CH), 5.38 (br s, 1H, COD), 5.24 (s, 1H, C1-H),
4.82 (br s, 1H, COD), 4.55 (br s, 1H, COD), 3.84 (br s, 1H, COD),
3.20-2.80 (br m, 6H, NMe2), 2.69-2.45 (m, 4H, P(CHMecMed),
P(CHMeaMeb) and COD), 2.40-2.21 (m, 4H, COD), 1.96 (d of d,
2
NMR (CD2Cl2): δ 223.2 (CO), 141.5 (d, JPC ) 21.4 Hz, C2),
130.5 (aryl CH), 129.1 (C4 or C7), 127.3 (C5 or C6), 122.8 (aryl
CH), 108.0 (t, J ) 7.4 Hz, COD), 102.5 (COD), 100.9 (m, aryl C),
77.4 (d, J ) 12.5 Hz, COD), 71.3 (d, J ) 12.5 Hz, COD), 68.3 (d,
3JPC ) 11.7 Hz, C1), 56.6 (NMe), 50.6 (NMe), 35.1 (COD), 30.6
3
3JHH ) 7.5 Hz, JPH ) 17.5 Hz, 3H, P(CHMedMec)), 1.99-1.82
3
3
(m, 2H, COD), 1.59 (d of d, JHH ) 7.0 Hz, JPH ) 14.0 Hz, 3H,
3
1
P(CHMedMec)), 1.55 (s, 15H, C5Me5), 1.15 (d of d, JHH ) 7.0
(COD), 29.6 (COD), 27.6 (d, JPC ) 22.6 Hz, P(CHMecMed) or
P(CHMeaMeb)), 25.8 (P(CHMeaMeb) or P(CHMecMed)), 25.6
(COD), 22.7 (P(CHMeaMeb)), 20.1 (d, JPC ) 3.2 Hz, (P(CHMec-
Hz, 3JPH ) 15.0 Hz, 3H, P(CHMebMea)), 0.94 (d of d, 3JHH ) 7.5
Hz, JPH ) 17.5 Hz, 3H, P(CHMebMea)). 13C{1H} NMR (CD2-
3
2

6426 Organometallics, Vol. 26, No. 25, 2007
Wechsler et al.
2
Med)), 19.3 (d, JPC ) 3.5 Hz, P(CHMecMed)), 18.8 (P(CH-
Cp*FeCl (0.56 mmol) in THF (2 mL) (prepared in a manner
analogous to that described for the synthesis of 2c), which had been
precooled to -35 °C. After the mixture had been stirred magneti-
cally at ambient temperature for 2 h, the solvent and other volatile
materials were removed in vacuo, and the residue was taken up in
pentane (5 mL) followed by filtration through a short plug of Celite.
The filtrate was then passed through a short Florisil plug, and the
plug was washed with additional pentane (10 mL). The combined
pentane eluent was then concentrated and dried in vacuo. Any
decamethylferrocene that was produced during the synthesis was
then removed via sublimation to leave 6c as an analytically pure,
purple-brown waxy solid (0.10 g, 0.24 mmol, 43%). Anal. Calcd
for C25H35PFe: C, 71.07; H, 8.36; N, 0.00. Found: C, 71.29; H,
8.21; N < 0.3. 1H NMR (CD2Cl2): δ 7.73 (d, 3JHH ) 9.0 Hz, 1H,
C4-H), 7.22 (d, 3JHH ) 8.5 Hz, 1H, C7), 6.98-6.88 (m, 2H, C5-H
and C6-H), 4.35 (d, 3JHH ) 2.5 Hz, 1H, C1-H), 3.74 (d, 3JHH ) 2.5
Hz, 1H, C2-H), 2.55 (m, 1H, P(CHMecMed)), 1.83 (m, 1H,
MeaMeb)). 31P{1H} NMR (CD2Cl2): δ 44.5 (d, 1JPRh ) 151.8 Hz).
FTIR (cm-1) ν(CO): 2025, 1953, 1933.
Synthesis of [4c]+BF4-. A procedure analogous to that described
-
for the synthesis of [4b]+BF4 was employed, using 3c (0.044 g,
0.095 mmol) in THF (2 mL). Complex [4c]+BF4- was isolated as
a dark purple solid (0.068 g, 0.089 mmol, 89%). Anal. Calcd for
C35H52PNFeRhBF4: C, 55.04; H, 6.87; N, 1.83. Found: C, 54.83;
1
3
H, 7.06; N, 1.52. H NMR (CD2Cl2): δ 7.50 (d, JHH ) 5.3 Hz,
1H, C7-H or C4-H), 7.34 (m, 1H, aryl CH), 7.31-7.27 (m, 2H,
aryl CH), 5.42 (br s, 1H, COD), 4.93 (s, 1H, C1-H), 4.80 (m, 1H,
COD), 4.62 (m, 1H, COD), 4.07 (m, 1H, COD), 3.06 (s, 3H, NMe),
2.98-2.91 (m, 4H, NMe and P(CHMecMed)), 2.67 (m, 1H, COD),
2.52 (m, 3H, COD), 2.36 (m, 2H, COD and P(CHMebMea)), 2.26
3
3
(m, 2H, COD), 2.11 (d of d, JPH ) 15.9 Hz, JHH ) 7.2 Hz, 3H,
P(CHMecMed)), 2.04 (m, 1H, COD), 1.74 (d of d, 3JPH ) 23.4 Hz,
3JHH ) 6.8 Hz, 3H, P(CHMecMed)), 1.60 (s, 15H, C5Me5), 1.21 (d
of d, 3JPH ) 15.1 Hz, 3JHH ) 7.0 Hz, 3H, P(CHMeaMeb)), 0.78 (d
of d, 3JPH ) 16.1 Hz, 3JHH ) 6.8 Hz, 3H, P(CHMeaMeb)). 13C{1H}
NMR (CD2Cl2): δ 128.5 (C4 or C7), 127.3 (aryl CH), 126.1 (aryl
CH), 125.9 (aryl CH), 105.5 (t, J ) 8.4 Hz, COD), 102.2 (t, J )
10.0 Hz, COD), 94.2 (quat.), 83.6 (quat.), 79.3 (C5Me5), 75.5 (d, J
) 12.4 Hz, COD), 71.8 (d, J ) 12.3 Hz, COD), 55.8 (d, J ) 8.9
Hz, C1), 55.6 (NMe), 52.1 (NMe), 33.6 (COD), 31.0 (COD), 29.7
(COD), 27.1-26.6 (P(CHMecMed), P(CHMeaMeb), and COD), 22.0
(P(CHMecMed)), 20.6 (P(CHMeaMeb)), 19.9 (P(CHMecMed)), 19.5
(P(CHMeaMeb)), 9.9 (C5Me5). 31P{1H} NMR (CD2Cl2): δ 43.8 (d,
1JPRh ) 150.0 Hz). Crystals of [4c]+BF4- suitable for single-crystal
X-ray diffraction analysis were grown from THF at -35 °C.
Synthesis of 6b. A glass vial charged with a stir bar, 3-PiPr2-
indene (0.30 g, 1.29 mmol), and THF (3 mL) was cooled to
-35 °C. To this vial was added dropwise via Eppendorf pipet a
1.6 M hexanes solution of n-BuLi (0.81 mL, 1.29 mmol; precooled
to -35 °C), after which the mixture was stirred magnetically for 1
h at ambient temperature. The reaction mixture was then cooled to
-35 °C, to which was added a solution of [Cp*RuCl]4 (0.35 g,
0.32 mmol) in THF (2 mL) (precooled to -35 °C). The mixture
was stirred magnetically at ambient temperature for 18 h, after
which the solvent was removed in vacuo and the residue was taken
up in diethyl ether (5 mL) followed by filtration through a plug of
Celite. The filtrate was then concentrated and dried in vacuo,
affording 6b as an analytically pure, dark yellow solid (0.59 g,
1.26 mmol, 98%). Anal. Calcd for C25H35PRu: C, 64.20; H, 7.55;
3
P(CHMeaMeb)), 1.59 (s, 15H, C5Me5), 1.53 (d of d, JPH ) 18.5
3
Hz, JHH ) 7.5 Hz, 3H, P(CHMecMed)), 1.29 (apparent t, J ) 6.5
Hz, 3H, P(CHMecMed)), 1.13 (d of d, 3JPH ) 15.0 Hz, 3JHH ) 7.0
Hz, 3H, P(CHMebMea)), 0.80 (d of d, 3JPH ) 12.0 Hz, 3JHH ) 7.0
Hz, 3H, P(CHMebMea)). 13C{1H} NMR (CD2Cl2): δ 126.8 (d, 3JPC
) 7.6 Hz, C4), 125.4 (C7), 121.4 (C6), 119.8 (C5), 90.6 (d, 2JPC
)
4
20.5 Hz, C3a), 89.1 (d, JPC ) 3.1 Hz, C7a), 75.5 (C5Me5), 73.6
2
1
(d, JPC ) 3.7 Hz, C2), 69.9 (d, JPC ) 20.5 Hz, C3), 66.6 (C1),
1
2
22.9 (d, JPC ) 16.6 Hz, P(CHMeMe)), 22.1 (d, JPC ) 30.4 Hz,
1
P(CHMedMec)), 21.1 (d, JPC ) 12.1 Hz, P(CHMeMe)), 19.9 (d,
2JPC ) 22.2 Hz, P(CHMebMea)), 19.2 (d, JPC ) 12.2 Hz,
2
P(CHMebMea)), 17.3 (P(CHMecMed)), 8.0 (C5Me5). 31P{1H} NMR
(CD2Cl2): δ -12.4.
Synthesis of 7. A glass vial was charged with a stir bar, 6b (0.10
g, 0.22 mmol), and THF (2 mL). To this vial was added a solution
of [(COD)RhCl]2 (0.054 g, 0.11 mmol) in THF (4 mL). The
combined mixture was stirred for 2 h at ambient temperature, after
which the solvent and other volatile materials were removed in
vacuo. To the residual solid was added pentane (5 mL), and the
mixture was filtered though a plug of Celite. The filtrate was
collected and dried in vacuo, affording 7 as an analytically pure,
yellow-orange solid (0.15 g, 0.21 mmol, 96%). Anal. Calcd for
C33H47PRuRhCl: C, 55.48; H, 6.64; N, 0.00. Found: C, 55.66; H,
6.39; N < 0.3. 1H NMR (C6D6): δ 8.36 (br s, 1H, C4-H or C7-H),
6.88-6.83 (m, 3H, aryl CHs), 5.77 (br s, 1H, COD), 5.71 (m, 1H,
COD), 4.46 (d, 3JHH ) 2.4 Hz, 1H, C2-H), 4.31 (br s, 1H, C1-H),
3.87 (br s, 1H, COD), 3.75 (br s, 1H, COD), 2.94 (m, 1H, P(CHMea-
Meb)), 2.64 (m, 1H, P(CHMecMed)), 2.25-2.20 (m, 3H, COD),
2.09 (m, 1H, COD), 1.74-1.58 (m, 9H, COD and P(CHMecMed)),
1.44 (s, 15H, C5Me5), 1.40 (d of d, 3JPH ) 14.9 Hz, 3JHH ) 6.9 Hz,
3H, P(CHMeaMeb)), 1.33 (m, 1H, COD), 0.95 (m, 3H, P(CH-
MeaMeb)). 13C{1H} NMR (C6D6): δ 128.0 (C4 or C7), 124.5 (aryl
CH), 122.7 (aryl CH), 120.9 (aryl CH), 102.3-101.9 (m, COD),
1
N, 0.00. Found: C, 64.19; H, 7.35; N < 0.3. H NMR (C6D6): δ
3
3
7.52 (d, JHH ) 8.5 Hz, 1H, C4-H or C7-H), 6.95 (d, JHH ) 8.2
Hz, 1H, C7-H or C4-H), 6.80-6.75 (m, 2H, C5-H and C6-H), 4.69
(d, 3JHH ) 2.5 Hz, 1H, C1-H), 4.44 (d, 3JHH ) 2.5 Hz, 1H, C2-H),
2.25 (m, 1H, P(CHMeMe)), 1.85 (m, 1H, P(CHMeMe)), 1.53 (s,
3
3
15H, C5Me5), 1.42 (d of d, JPH ) 18.0 Hz, JHH ) 7.5 Hz, 3H,
P(CHMeMe)), 1.23 (apparent t, J ) 7.3 Hz, 3H, P(CHMeMe)),
1.08 (d of d, JPH ) 14.5 Hz, JHH ) 7.0 Hz, 3H, P(CHMeMe)),
2
3
3
3
95.0 (d, JPC ) 11.6 Hz, C3a), 94.6 (d, JPC ) 5.6 Hz, C7a), 82.9
2
1
3
3
(C5Me5), 80.9 (C1), 71.6 (d, JPC ) 4.2 Hz, C2), 68.9 (d, JRhC
)
1.08 (d of d, JPH ) 12.0 Hz, JHH ) 7.0 Hz, 3H, P(CHMeMe)).
13C{1H} NMR (C6D6): δ 126.2 (d, JPC ) 8.0 Hz, aryl C), 124.7
(aryl C), 121.8 (aryl C), 120.3 (aryl C), 96.4 (d, J ) 23.2 Hz, C3a
or C7a), 94.0 (d, J ) 2.9 Hz, C7a or C3a), 82.3 (C5Me5), 77.7 (d,
2JPC ) 4.6 Hz, C2), 76.5 (d, 1JPC ) 21.3 Hz, C3), 70.5 (C1), 25.3
(d, JPC ) 15.7 Hz, P(CHMeMe)), 24.0 (d, JPC ) 28.6 Hz,
P(CHMeMe)), 23.4 (d, 1JPC ) 11.2 Hz, P(CHMeMe)), 21.1 (d, 2JPC
) 20.8 Hz, P(CHMeMe)), 20.4 (d, 2JPC ) 12.0 Hz, P(CHMeMe)),
19.5 (P(CHMeMe)), 10.3 (C5Me5). 31P{1H} NMR (C6D6): δ -10.4.
Synthesis of 6c. A glass vial charged with a stir bar, 3-PiPr2-
indene (0.13 g, 0.56 mmol), and THF (2 mL) was cooled to
-35 °C. To this vial was added dropwise via Eppendorf pipet a
1.6 M hexanes solution of n-BuLi (0.35 mL, 0.56 mmol; precooled
to -35 °C), after which the mixture was stirred magnetically for 1
h at ambient temperature. This mixture was cooled to -35 °C and
then was transferred slowly to a vial containing a solution of
1
13.5 Hz, COD), 68.6 (d, JRhC ) 13.1 Hz, COD), 33.6 (COD),
32.9 (COD), 28.9 (COD), 27.9 (COD), 27.0 (m, P(CHMeaMeb)
and P(CHMecMed)), 21.4 (P(CHMecMed)), 20.8 (P(CHMeaMeb)),
20.1 (P(CHMecMed)), 19.0 (br s, P(CHMeaMeb)), 10.3 (C5Me5).
31P{1H} NMR (C6D6): δ 28.2 (d, JRhP ) 142.1 Hz).
1
1
2
General Protocol for Hydroboration Experiments. The pro-
tocols employed are based on those described by Crudden and co-
workers.17a A solution of catalyst compound in the desired solvent
(0.019 mmol in 0.95 mL to give a 0.02 M solution) was allowed
to equilibrate for 5 min within a reaction vial containing a stir bar,
at which point styrene (0.38 mmol) was added to the vial by use
of an Eppendorf pipet. The vial was then sealed with a PTFE-
lined cap and stirred for 10 min. Subsequently, pinacolborane (0.46
mmol) was added to the reaction mixture by use of an Eppendorf
pipet, the vial was resealed, and the reaction mixture was left to

Planar-Chiral Metalloligands
Organometallics, Vol. 26, No. 25, 2007 6427
stir magnetically at 24 °C for 24 h. After this time, the reaction
mixture was concentrated in vacuo, and hexanes (1 mL) was added
to the residue. The resultant mixture was then filtered through a
short silica gel column (0.6 cm × 5 cm) and eluted with 5 mL of
a 20:1 hexanes:ethyl acetate solution. The eluted colorless solution
was then concentrated and taken up in diethyl ether (4 mL). To
convert the boronate ester products to the corresponding alcohols,
the diethyl ether solution was cooled to 0 °C and NaOH (1 mL of
a 3 N aqueous solution) was added, followed by H2O2 (1 mL of a
30% aqueous solution). After stirring at 0 °C for 1 h, then at ambient
temperature for 1-2 h, the reaction mixture was diluted with diethyl
ether (∼4 mL) and distilled water (∼5 mL). The organic layer was
separated and retained, and the aqueous layer was extracted with
diethyl ether (2 × 4 mL). The combined organic extracts were
washed with brine, dried over Na2SO4, filtered, and partially
concentrated. This resulting solution was then transferred to a GC
vial and sealed. Quantitative data for the derived alcohols were
obtained from GC-FID analysis. Tabulated data represent the
average of at least two runs. GC-FID method: temperature control,
80 °C for 15 min, then increased by 10 °C/min to 180 °C, 180 °C
for 5 min. Column: Supelco 30 m × 0.25 mm BETA-DEX 120,
film thickness 0.25 µm. He flowrate: 15 psi.
software.22a Data reduction and absorption correction were also
performed with the HKL DENZO and SCALEPACK software. The
structures were solved by using the direct methods package in SIR-
9722b and refined by use of the SHELXL97-2 program,22c employing
full-matrix least-squares procedures (on F2) with R1 based on Fo
2
2
2
2
g 2σ(Fo ) and wR2 based on Fo g -3σ(Fo ). Anisotropic
displacement parameters were employed throughout for the non-
hydrogen atoms. For [4c]+BF4-, the final refined value of the
absolute structure parameter (-0.02(2); 3396 Friedel pairs) sup-
ported that the correct absolute structure had been chosen.22d,e For
7, two crystallographically independent molecules were identified
in the asymmetric unit, and during the refinement process the
restraints DELU, SIMU, and ISOR were employed to restrain the
anisotropic displacement parameters of the carbon atoms of the
disordered C5Me5 ligands. All H-atoms were added at calculated
positions and refined by use of a riding model employing isotropic
displacement parameters based on the isotropic displacement
parameter of the attached atom. Additional crystallographic infor-
mation is provided in the accompanying CIF.
Acknowledgment. We acknowledge the Natural Sciences
and Engineering Research Council (NSERC) of Canada (includ-
ing a Collaborative Research and Development Grant for M.S.
and Postgraduate Scholarships for D.W. and M.A.R.), Boe-
hringer Ingelheim (Canada) Ltd., Dalhousie University (includ-
ing the Department of Chemistry, and the Industry Liaison and
Innovation Office for a Research Innovation Award), Innova-
corp, the Springboard Atlantic Network, the Canada Foundation
for Innovation, and the Nova Scotia Research and Innovation
Trust Fund for their generous support of this work. We also
thank Dr. Michael Lumsden (Atlantic Region Magnetic Reso-
nance Center, Dalhousie) for his assistance in the acquisition
of NMR data.
Crystallographic Characterization of 2a, 2b, 2c, and 3b.
Crystallographic data for each of these complexes were obtained
at 193((2) K on a Bruker PLATFORM/SMART 1000 CCD
diffractometer using a graphite-monochromated Mo KR (λ )
0.71073 Å) radiation, employing a sample that was mounted in
inert oil and transferred to a cold gas stream on the diffractometer.
Programs for diffractometer operation, data collection, data reduc-
tion, and multiscan absorption correction (including SAINT and
SADABS) were supplied by Bruker. The structures were solved
by use of direct methods in the case of 2c and 3b, or a Patterson
search/structure expansion in the case of 2a and 2b, and refined
by use of full-matrix least-squares procedures (on F2) with R1 based
2
2
2
2
on Fo g 2σ(Fo ) and wR2 based on Fo g -3σ(Fo ). Anisotropic
displacement parameters were employed throughout for the non-H
atoms, and all H-atoms were added at calculated positions and
refined by use of a riding model employing isotropic displacement
parameters based on the isotropic displacement parameter of the
attached atom. Additional crystallographic information is provided
in the accompanying CIF.
Supporting Information Available: Single-crystal X-ray dif-
fraction data in CIF format for 2a, 2b, 2c, 3b, [4c]+BF4-, and 7.
This material is available free of charge via the Internet at
http://pubs.acs.org.
OM700832F
(22) (a) HKL DENZO and SCALEPACK v1.96: Otwinowski, Z.; Minor,
W. In Macromolecular Crystallography, Part A; Carter, C. W., Jr., Sweet,
R. M., Eds.; Academic Press: San Diego, CA, 1997; Vol. 276, pp 307-
326. (b) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A.;
Moliterni, A. G. G.; Burla, M. C.; Polidori, G.; Camalli, M.; Spagna, R. J.
Appl. Crystallogr. 1999, 32. (c) Sheldrick, G. M. SHELXL97-2, Program
for the Solution of Crystal Structures; University of Go¨ttingen: Go¨ttingen,
Germany, 1997. (d) Flack, H. D. Acta Crystallogr., Sect. A 1983, A39, 876.
(e) Flack, H. D.; Bernardinelli, G. Acta Crystallogr., Sect. A 1999, A55,
908.
Crystallographic Characterization of [4c]+BF4- and 7. Crys-
tallographic data for each of these complexes were obtained at 173-
((2) K on a Nonius KappaCCD 4-Circle Kappa FR540C diffrac-
tometer using a graphite-monochromated Mo KR (λ ) 0.71073
Å) radiation, employing a sample that was mounted in inert oil
and transferred to a cold gas stream on the diffractometer. Cell
parameters were retrieved initially by using the COLLECT software
(Nonius) and refined with the HKL DENZO and SCALEPACK