Synthesis and characterization of new chiral palladium β-diimine complexes

Article abstract of DOI:10.1016/j.jorganchem.2006.10.064

The synthesis and characterization of a range of chiral β-diimine ligands and their complexes with palladium(II) has been investigated. The introduction of chirality can be easily achieved through a combination of both achiral and chiral building blocks.

Full text of DOI:10.1016/j.jorganchem.2006.10.064

Journal of Organometallic Chemistry 692 (2007) 1048–1057
www.elsevier.com/locate/jorganchem
Synthesis and characterization of new chiral palladium
b-diimine complexes
a
a
b
a
Doris Domin , David Benito-Garagorri , Kurt Mereiter , Christian Hametner ,
a,
a,
*
Johannes Frohlich *, Karl Kirchner
¨
a
Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria
b
Received 14 September 2006; received in revised form 21 October 2006; accepted 31 October 2006
Available online 7 November 2006
Dedicated to Professor Miha Tisˆler, Professor Emeritus of the University of Ljubljana, on the occasion of his 80th birthday.
Abstract
The synthesis and characterization of a range of chiral b-diimine ligands and their complexes with palladium(II) has been investigated.
The introduction of chirality can be easily achieved through a combination of both achiral and chiral building blocks. The absolute con-
figuration of the stereochemical centers has been determined. In addition, representative X-ray structures of both ligands and complexes
have been determined.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: b-Diimines; Chiral ligands; Palladium(II); Square-planar complexes
1. Introduction
giving rise to the formation of b-diketiminate complexes [7]
and other products [8] rather than b-diimine complexes.
Recently, Woods and co-workers synthesized several b-dii-
mine ligands in which the problematic CH acidity was cir-
cumvented by diimine dialkylation [9]. In a subsequent
paper, these authors described the synthesis of some palla-
dium b-diimine complexes and provided structural com-
parisons with the corresponding a-diimine analogues [10].
We recently reported the synthesis and reactivity of a series
of sterically demanding non-chiral b-diimine ligands as well
as their Ni(II) and Pd(II) complexes, where the central car-
bon atoms of the ligands were part of five- and six-mem-
bered rings in order to ensure that the ligands kept their
diimine character even under basic conditions [11].
In the present contribution we extend our synthetic
efforts to obtain novel chiral b-diimine ligands, where chi-
rality can be introduced into two different positions of the
ligands by using a combination of chiral and achiral build-
ing blocks. Condensation of an achiral dialdehyde with chi-
ral amines renders the ligands chiral at the diimine
moieties, whereas a chiral dialdehyde and an achiral amine
Nickel and palladium complexes containing sterically
demanding a-diimine (diazabutadiene) ligands are highly
efficient catalysts for olefin polymerizations [1–3], alkyne
cyclotrimerizations [4] and, as shown recently, also for
Suzuki cross-coupling reactions [5]. On the other hand,
few investigations have focused on the chemistry of analo-
gous nickel and palladium b-diimine complexes. Feldman
et al. reported the synthesis of a sterically hindered b-dii-
mine ligand bearing no substituents at the Cb atom and
examined its reactions with Ni(II) and Pd(II) catalyst pre-
cursors [6]. However, b-diimines lacking substituents at
the central carbon atom typically form hydrogen-bridged
b-iminoamine tautomers. Accordingly, in the presence of
base, e.g., under catalytic conditions, deprotonation occurs
*
Corresponding authors. Fax.: +43 1 58801 15341; fax: +43 1 58801
15499 (K. Kirchner).
E-mail addresses: jfroehli@ioc.tuwien.ac.at (J. Fro¨hlich), kkirch@
mail.zserv.tuwien.ac.at (K. Kirchner).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.10.064

D. Domin et al. / Journal of Organometallic Chemistry 692 (2007) 1048–1057
1049
leaves the ligand backbone chiral. A combination of these
possibilities finally affords ligands which are chiral both at
the ligand backbone and at the diimine functionality.
Moreover, the synthesis of a series of Pd(II) complexes
with our new ligands is described. Representative X-ray
structures of ligands and palladium complexes are
reported.
To introduce chirality into the cyclic framework, the
synthesis of a chiral dialdehyde was necessary (Scheme
2). After asymmetric reduction of 1,4-diphenylbutane-1,4-
dione using commercially available (ꢀ)-DIP-chloride the
resulting diol (S,S)-2 was converted into the dimesylate
(S,S)-3 using an optimized procedure [12]. The cyclization
step was carried out by alkylation with malonic acid
diethylester and sodium hydride in the presence of
15-Crown-5 to yield the enantiomerically pure diethyl mal-
onate (R,R)-4. Traces of (meso)-diester were easily removed
by column chromatography.
2. Results and discussion
2.1. Synthesis of the ligands
Reduction with lithium aluminum hydride to the diol
(R,R)-5 followed by a Swern oxidation gave the dialdehyde
(R,R)-6 in an excellent yield. The enantiomeric excess was
estimated by synthesis of the racemic diol (rac)-5 and
(meso)-5 and HPLC as well as by 19F NMR analysis of
their Mosher esters (see Supplementary material,
Following the methodology established previously [11]
the b-diimine ligands were synthesized by condensation
of 1,1-cyclopentanedicarbaldehyde and various amines.
By using chiral amines diimines bearing chirality at the dii-
mine moiety were obtained (Scheme 1).
(R) or (S) PhCH(CH3)NH2
C6H6, reflux, 2.5 h
(R) or (S) PhCH2CH(CH2OCH3)NH2
C6H6, reflux, 2.5 h
N
N
N
N
O
O
O
O
1a: (S,S)
1b: (R,R)
1c: (S,S)
1d: (R,R)
Scheme 1.
O
OH
OMs
(-)-DIP-chlorideTM, diethanolamine
THF, -78˚C to RT, 22h
MsCl, Et3N
Ph
Ph
Ph
Ph
Ph
Ph
CH2Cl2, -20˚C, 2h
O
OH
Ph
OMs
2
3
Ph
Ph
Ph
LiAlH4
NaH, EtOOCCH2COOEt, 15-crown-5
THF, RT to reflux, 7h
DMSO, Et3N, (COCl)2
CH2Cl2, -78˚C to RT, 4h
Ph
Ph
EtOOC
COOEt
THF, 5˚C to RT, 3h
OH
OH
O
O
4
5
6
Scheme 2.
Ph
Ph
(R) or (S) PhCH(CH3)NH2
Toluene, reflux, 5 h
(R) or (S) PhCH2CH(CH2OCH3)NH2
Toluene, reflux, 5 h
Ph
Ph
Ph
Ph
N
N
N
N
O
O
O
O
6
2,6-Me2PhNH2
p-TsOH
Toluene, reflux, 3h
8b: (R,R,S,S)
8c: (R,R,R,R)
8d: (R,R,S,S)
8e: (R,R,R,R)
Ph
Ph
N
N
8a
Scheme 3.

1050
D. Domin et al. / Journal of Organometallic Chemistry 692 (2007) 1048–1057
compounds 10). The absolute configuration of the cyclic
framework was determined by single crystal X-ray analysis
of the 4-bromobenzoic acid ester of the diol (R,R)-5 (see
Supporting Information, compound (R,R)-11). The con-
densation to (R,R)-b-diimines was carried out with 2,6-
dimethylaniline and different chiral amines (Scheme 3).
Because of the steric hindrance of the dialdehyde (R,R)-5
higher reaction temperatures and longer reaction periods
than for the condensation of the achiral dialdehyde were
necessary.
2.2. Synthesis of the complexes
In a similar manner as for the achiral palladium(II) b-
diimine complexes reported previously [11], treatment of
PdCl2(CH3CN)2 or Pd(COD)Cl2 with the ligands 1a–d
and 7a–e in refluxing CH3CN or CH2Cl2 afforded com-
plexes 8–9 in good isolated yields (Scheme 4 and 5). The
syntheses of the bromide complexes, exemplarily
shown for 8e, proceeds in an analogous way using
PdBr2(CH3CN)2 as precursor. All complexes are thermally
robust yellow or beige solids that are stable to air both in
the solid state and in solution (Fig. 1).
Fig. 1. Structural view of 7a showing 30% thermal ellipsoids. Hydrogen
atoms omitted for clarity.
1
7.50–7.01 ppm in the H NMR spectrum. Likewise, in the
13C{1H} NMR spectrum, the imine carbon atom exhibits
a singlet resonance at about 170 ppm. As expected, the
NMR spectra of the diastereomeric complexes exhibiting
different stereochemistry at the cyclopentyl group or at
the imine substituents show little differences. Structural
views of 8a, 9a, and 9b as determined by X-ray crystallog-
raphy (Table 1) are depicted in Figs. 2–4. The expected
bidentate coordination of the diimine nitrogen atoms to
the Pd(II) center, forming distorted square planar coordi-
nation environments, is found for all three complexes
(Figs. 2–4, Table 2), as was for the related achiral b-diimine
complexes [11]. Likewise, the six-membered chelate ring
adopts a boat conformation, resulting from the presence
of two planar Pd–N(sp2)@CH(sp2)–C systems and two
comparatively low bond angles N1–Pd–N2 ꢁ 90ꢁ and
C1–C2–C3 ꢁ 110ꢁ in the chelate ring (Table 2).
The identity of the complexes was established by 1H and
13C{1H} NMR spectroscopy. The NMR spectra of 8–9
bear no unusual features, with a characteristic singlet reso-
nance of the proton of the CH@N moiety in the range
N
N
R
R
R
N
1a-d
N
PdX2(CH3CN)2
or Pd(COD)Cl2
X = Cl, Br
Pd
R
X
CH3CN or CH2Cl2
reflux, 2h
X
Altogether, we report here an efficient synthesis of a
broad spectrum of new sterically hindered and chiral
N,N0-diaryl and dialkyl b-diimines with the central carbon
atom being part of a five-membered ring system to avoid
the formation of b-diketiminates. These compounds are
excellent ligands for the preparation of Pd(II) complexes
and may be useful as catalysts for C–C coupling reactions.
However, preliminary studies revealed that these com-
plexes are not suited as catalysts for the asymmetric Heck
reaction between dihydrofurane and iodobenzene and in
the Tsuji–Trost asymmetric allylic alkylation. Investiga-
tions about the applicability of these complexes in other
Pd(II) catalyzed asymmetric reactions are currently
ongoing.
8a X = Cl, R = CH(CH3)Ph (S,S)
8b X = Cl, R = CH(CH3)Ph (R,R)
8c X = Cl, R = CH(OCH3)CH2Ph (S,S)
8d X = Cl, R = CH(OCH3)CH2Ph (R,R)
8e X = Br, R = CH(CH3)Ph (R,R)
Scheme 4.
Ph
Ph
R
Ph
N
N
R
N
R
Ph
N
7a-e
PdCl2(CH3CN)2
or Pd(COD)Cl2
Pd
R
Cl
CH3CN or CH2Cl2
reflux, 2h
Cl
3. Experimental
9a R = 2,6-Me2Ph (R,R)
9b R = CH(CH3)Ph (R,R,S,S)
9c R = CH(CH3)Ph (R,R,R,R)
9d R = CH(OCH3)CH2Ph (R,R,S,S)
9e R = CH(OCH3)CH2Ph (R,R,R,R)
3.1. General
All manipulations were performed under an inert atmo-
sphere of argon by using Schlenk techniques. (ꢀ)-DIP-
chlorideꢂ was purchased from Aldrich and used as
Scheme 5.

D. Domin et al. / Journal of Organometallic Chemistry 692 (2007) 1048–1057
1051
Table 1
Details for the crystal structure determinations of 7a, 8a, 9a, and 9b
7a
8ab
9a
9b
Formula
Fw
C
35H36N2
C23H28Cl2N2Pd
509.77
C35H36Cl2N2Pd
661.96
C35H36Cl2N2Pd
661.96
0.35 · 0.17 · 0.13
P212121 (no. 19)
11.4410(6)
14.0683(7)
19.1121(9)
90
90
90
3076.2(3)
4
1.429
484.66
0.42 · 0.39 · 0.25
P212121 (no. 19)
7.8664(4)
18.7554(10)
18.7965(10)
90
90
90
2773.2(3)
4
1.161
Crystal size (mm)
Space group
0.42 · 0.19 · 0.11
P21 (no. 4)
15.375(3)
7.4073(16)
24.909(5)
90
92.099(4)
90
2835.0(11)
4 (Z0 = 2)
1.194
0.38 · 0.18 · 0.10
P212121 (no. 19)
10.9061(5)
20.8972(10)
27.3501(14)
90
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
3
˚
V (A )
6233.3(5)
8 (Z0 = 2)
1.411
297(2)
0.793
Z
qcalc (g cmꢀ3
T (K)
)
173(2)
0.067
1040
173(2)
0.852
1040
173(2)
0.804
1360
l (mmꢀ1) (Mo-Ka)
F(000)
2720
hmax (ꢁ)
27
25440
6042
5656
338
0.0353
0.0386
0.0909
30
52626
16307
15529
505
0.0357
0.0380
0.0918
30
94114
18169
15303
729
0.0325
0.0449
0.0716
30
45799
9022
8520
Number of reflections measured
Number of unique reflections
Number of reflections I > 2r(I)
Number of parameters
R1 (I > 2r(I))a
R1 (all data)
wR2 (all data)
Differences in Four. peaks min/max (e A
361
0.0263
0.0291
0.0676
ꢀ0.19/0.92
ꢀ3
˚
)
ꢀ0.17/0.21
ꢀ0.83/1.34
ꢀ0.36/0.40
P
P
P
P
2
2
1=2
a
R1 =
jjFoj ꢀ jFcjj/ jFoj, wR2 ¼ ½ ðwðF 2o ꢀ F c2Þ Þ= ðwðF o2Þ Þꢂ
.
b
8a was a solvate with disordered solvent. Chemical formula and derived quantities given without solvent content.
Fig. 3. Structural view of 9a showing 20% thermal ellipsoids. Hydrogen
atoms omitted for clarity.
Fig. 2. Structural view of 8a showing 20% thermal ellipsoids. Hydrogen
atoms omitted for clarity.
received. All other chemicals were standard reagent grade
and were used without further purification. The solvents
were purified according to standard procedures [13]. The
deuterated solvents were purchased from Aldrich and dried
over 4 A molecular sieves. 1,4-Diphenylbutane-1,4-dione
[14], 1,1-cyclopentanedicarbaldehyde [11], a-(methoxym-
ethyl)benzeneethanamine [15], 4-bromobenzoylchloride
[16], (R)-a-methoxy-a-(trifluoromethyl)phenylacetoyl chlo-
ride [17] and Pd(COD)Cl2 [18] were prepared according to
literature procedures. 1H, and 13C{1H} spectra were
recorded on Bruker AVANCE 200 and 250 spectrometers
and were referenced to SiMe4. 19F{1H} NMR spectra were
˚

1052
D. Domin et al. / Journal of Organometallic Chemistry 692 (2007) 1048–1057
romethane/methanol 95:5). Bp: 70–80 ꢁC/0.01 mbar. 1H
NMR (CDCl3): d 7.95 (s, 2H, CHN), 7.54–7.20 (m, 10H,
HAr), 4.47 (q, J = 6.6 Hz, 2H, CH), 2.19–2.00 (m, 4H,
CH2), 1.87–1.67 (m, 4H, CH2), 1.59 (d, J = 6.7 Hz, 6H,
CH3). 13C{1H} NMR (CDCl3): d 165.8 (d), 145.3 (s),
128.1 (d), 126.4 (d), 126.3 (d), 68.9 (d), 56.6 (s), 33.6 (t),
24.9 (q), 24.7 (t).
3.2.2. N,N0-(1,1-Cyclopentylidenedimethylidyne)bis(R)-a-
methylbenzenemethanamine (1b)
1,1-Cyclopentanedicarbaldehyde (0.70 g, 5.55 mmol)
and (R)-a-methylbenzenemethanamine (1.35 g, 11.1 mmol)
gave analogously to the procedure described for 1a a color-
less oil. Yield: 1.24 g (67%). Rf = 0.61 (dichloromethane/
methanol 9:1). Bp: 70–80 ꢁC/0.02 mbar. 1H NMR
(CDCl3): d 7.85 (s, 2H, CHN), 7.45–7.17 (m, 10H, HAr),
4.38 (q, J = 6.7 Hz, 2H, CH), 2.15–1.89 (m, 4H, CH2),
1.80–1.61 (m, 4H, CH2), 1.50 (d, J = 6.7 Hz, 6H, CH3).
13C{1H} NMR (CDCl3): d 166.0 (d), 145.4 (s), 128.2 (d),
126.5 (d), 126.4 (d), 69.1 (d), 56.7 (s), 33.8 (t), 25.0 (q),
24.8 (t).
Fig. 4. Structural view of 9b showing 30% thermal ellipsoids. Hydrogen
atoms omitted for clarity.
Table 2
3.2.3. N,N0-(1,1-Cyclopentylidenedimethylidyne)bis((S)-a-
(methoxymethyl)benzeneethanamine) (1c)
1,1-Cyclopentanedicarbaldehyde (0.50 g, 3.96 mmol)
and (S)-a-(methoxymethyl)benzeneethanamine (1.31 g,
7.92 mmol) gave analogously to the procedure described
for 1a a colorless oil. Yield: 1.09 g (66%). Rf = 0.69
˚
Key distances and angles (A, ꢁ) for 7a, 8a, 9a and 9b
7a
8a
9a
9b
Pd–Cl(1)
Pd–Cl(2)
Pd–N(1)
Pd–N(2)
N(1)–C(1)
N(2)–C(2)
2.300(1)/
2.299(1)
2.305(1)/
2.300(1)
2.017(2)/
2.039(2)
2.028(2)/
2.013(2)
1.279(3)/
1.273(3)
1.274(3)/
1.270(4)
2.2933(7)/
2.2871(7)
2.2727(7)/
2.2867(7)
2.039(2)/
2.036(2)
2.044(2)/
2.048(2)
1.267(3)/
1.274(3)
2.2900(5)
2.3139(5)
2.017(2)
2.004(2)
1.260(3)
1.264(2)
(dichloromethane/methanol
9:1).
Bp:
130–140 ꢁC/
1
0.02 mbar. H NMR (CDCl3): d 7.19–6.94 (m, 12H, HAr
and CHN), 3.48–3.19 (m, 12H, CH3 and CH2 and CH),
2.85 (dd, J = 13.6 Hz, 3.4 Hz, 2H, CH2), 2.61 (dd,
J = 13.4 Hz, 8.4 Hz, 2H, CH2), 1.73–1.56 (m, 2H, CH2),
1.54–1.26 (m, 6H, CH2). 13C{1H} NMR (CDCl3): d
167.9 (d), 138.8 (s), 129.6 (d), 127.9 (d), 125.8 (d),
75.9 (t), 71.7 (d), 58.9 (q), 56.5 (s), 39.0 (t), 33.3 (t),
24.6 (t).
1.2545(15)
1.2630(16)
1.282(3)/
1.274(3)
Cl(1)–Pd–Cl(2)
Cl(1)–Pd–N(1)
Cl(2)–Pd–N(2)
N(1)–Pd–N(2)
90.97(4)
91.62(7)
91.11(7)
86.25(10)
88.98(3)
91.14(6)
89.73(6)
90.12(7)
90.52(2)
91.53(5)
91.06(4)
86.74(6)
3.2.4. N,N0-(1,1-Cyclopentylidenedimethylidyne)bis((R)-a-
(methoxymethyl)benzeneethanamine) (1d)
1,1-Cyclopentane dicarbaldehyde (0.50 g, 3.96 mmol)
and (S)-a-(methoxymethyl)benzeneethanamine (1.31 g,
7.92 mmol) gave analogously to the procedure described
for 1a a colorless oil. Yield: 1.14 g (68%). Rf = 0.69 (dichlo-
recorded on a Bruker AVANCE 400 spectrometer. HPLC
method: Chiralcel OD-H (250 mm · 4.6 mm), 1 mL/min,
n-hexane/i-PrOH 95/5. 1H and 13C{1H} NMR signal
assignments were confirmed by 1H-COSY, 135-DEPT,
and HMQC(1H–13C) experiments.
1
romethane/methanol 9:1). Bp: 105–115 ꢁC/0.01 mbar. H
NMR (CDCl3): d 7.30–7.02 (m, 12H, HAr and CHN),
3.57–3.27 (m, 12H, CH3 and CH2 and CH), 2.95 (dd,
J = 13.5 Hz, 3.7 Hz, 2H, CH2), 2.69 (dd, J = 13.5 Hz,
8.4 Hz, 2H, CH2), 1.83–1.64 (m, 2H, CH2), 1.63–1.34 (m,
6H, CH2). 13C{1H} NMR (CDCl3): d 168.0 (d), 138.9 (s),
129.7 (d), 128.0 (d), 125.9 (d), 75.9 (t), 71.8 (d), 59.0 (q),
56.5 (s), 39.1 (t), 33.4 (t), 24.7 (t).
3.2. Synthesis of the ligands
3.2.1. N,N0-(1,1-Cyclopentylidenedimethylidyne)bis((S)-a-
methylbenzenemethanamine) (1a)
1,1-Cyclopentanedicarbaldehyde (0.20 g, 1.59 mmol),
(S)-a-methylbenzenemethanamine (0.38 g, 3.18 mmol),
and benzene (10 mL) was heated under reflux over a
Dean–Stark trap for 2.5 h. The solvent was evaporated
and the oily residue was purified by bulb-to-bulb distillation
to give a colorless oil. Yield: 0.50 g (95%). Rf = 0.41 (dichlo-
3.2.5. (1S,4S)-1,4-Diphenyl-1,4-butanediol (2)
Under an atmosphere of argon a solution of (ꢀ)-DIP-
chlorideꢂ (40.0 g, 125.0 mmol) in dry THF (140 mL) was

D. Domin et al. / Journal of Organometallic Chemistry 692 (2007) 1048–1057
1053
added dropwise over a period of 2 h to a solution of 1,4-
diphenyl-1,4-dione (14.1 g, 59.0 mmol) in dry THF
(140 mL) at ꢀ78 ꢁC. The reaction mixture was stirred 2 h
at ꢀ78 ꢁC and 18 h at room temperature. The solvent
was evaporated and the residue was stirred for 7 h at
40 ꢁC and 1 mbar. Then diethylether (400 mL) was added
and diethanolamine (14.5 g, 138.0 mmol) was given to the
solution at 0 ꢁC. The mixture was stirred 30 min at 0 ꢁC
and 18 h at room temperature. The precipitate was
removed by filtration over Hyflo and the solvent was evap-
orated. The crude product was purified by column chroma-
tography (petroleum ether/ethyl acetate 10:1 to 1:2) to give
colorless crystals. Yield: 8.15 g (57%). Rf= 0.44 (petroleum
solution was dried over Na2SO4 and the solvent was evapo-
rated. The crude product was purified by column chroma-
tography (petroleum ether/ethyl acetate 100:1) to give
colorless crystals. Yield: 3.0 g (57%). Rf = 0.68 (petroleum
20
ether/ethyl acetate 10:1). Mp: 84–86 ꢁC. ½aꢂD : +127.0ꢁ (c
1
1.009, EtOAc). H NMR (CDCl3): d 7.28–7.05 (m, 10H,
HAr), 4.33–4.17 (m, 2H, CH), 3.69 (dq, J = 10.6 Hz,
7.1 Hz, 2H, OCH2), 3.18 (dq, J = 10.7 Hz, 7.2 Hz, 2H,
OCH2), 2.31–1.93 (m, 4H, CH2), 0.61 (t, J = 7.2 Hz, 6H,
CH3). 13C{1H} NMR (CDCl3): d 170.7 (s), 141.2 (s), 128.7
(d), 127.9 (d), 126.8 (d), 70.7 (s), 60.7 (t), 52.3 (d), 32.1 (t),
13.2 (q). Anal. Calc. for C23H26O4 (366.46): C, 75.38; H,
7.15. Found: C, 75.22; H, 7.07%.
25
ether/ethyl acetate 1:1). Mp: 74–75 ꢁC. ½aꢂD : ꢀ59.05ꢁ (c
1
1.031, CHCl3). H NMR (CDCl3): d 7.31–7.11 (m, 10H,
3.2.8. (2R,5R)-2,5-Diphenylcyclopentane-1,1-dimethanol
(5)
HAr ), 4.64–4.52 (m, 2H, OH), 2.85 (s, 2H, CH), 1.93–
1.61 (m, 4H, CH2). 13C{1H} NMR (CDCl3): d 144.6 (s),
128.4 (d), 127.5 (d), 125.8 (d), 74.5 (d), 35.9 (t).
A solution of 4 (2.7 g, 7.3 mmol) in dry THF (16 mL)
was added dropwise over a period of 30 min to a suspension
of LiAlH4 (0.6 g, 16.1 mmol) in dry THF (34 mL) at 5 ꢁC.
The reaction mixture was stirred at room temperature for
3 h. After cooling to 5 ꢁC ethyl acetate (20 mL) was added
and the resulting solution was poured into 2 M HCl
(20 mL). After separation of the layers, the water layer
was extracted with ethyl acetate (5 · 20 mL). The combined
organic layers were washed with saturated NaCl-solution
(2 · 20 mL), dried over Na2SO4 and filtered. The solvent
was removed and the crude solid was recrystallized from a
mixture of diethylether/petroleum ether to give colorless
crystals. Yield: 1.8 g (88%). Rf= 0.63 (petroleum ether/ethyl
3.2.6. (1S,4S)-1,4-Diphenyl-1,4-butanediol-
bis(methanesulfonic acid ester) (3)
Under an atmosphere of argon a solution of 2 (3.8 g,
15.7 mmol) and triethylamine (4.9 g, 48.0 mmol) in dry
dichloromethane (152 mL) was added dropwise to metha-
nesulfonyl chloride (4.6 g, 40.5 mmol) in dry dichlorometh-
ane (152 mL) at ꢀ20 ꢁC. The reaction mixture was stirred
for 2 h at ꢀ20 ꢁC and saturated NH4Cl-solution (5 mL)
was added. After warming up to room temperature the sol-
vent was removed in vacuo to approx. 50 mL. Diethylether
(250 mL) was added and the solution was washed with
water/brine/saturated NaHCO3-solution 1:2:1 (4 · 50 mL)
and saturated NaHCO3-solution (2 · 50 mL). After drying
over NaSO4 the solvent was removed in vacuo to approx.
25 mL. The residue was cooled to 0 ꢁC and the product
was precipitated by dropwise addition of petroleum ether
(100 mL). After suction filtration the product was obtained
as colorless crystals. Yield: 5.2 g (83%). Rf = 0.21 (petro-
20
acetate 1:1). Mp: 77–78 ꢁC. ½aꢂD : +26.7ꢁ (c 1.113, CH2Cl2).
1H NMR (CDCl3): d 7.42–7.22 (m, 10H, HAr), 3.58 (m, 4H,
CH2OH), 3.34–3.19 (m, 2H, CH), 2.30–2.07 (m, 4H, CH2),
1.68 (s, 2H, OH). 13C{1H} NMR (CDCl3): d 141.2 (s), 128.6
(d), 128.5 (d), 126.7 (d), 68.0 (t), 52.7 (s), 50.3 (d), 30.6 (t).
Anal. Calc. for C19H22O2 (282.39): C, 80.82; H, 7.85.
Found: C, 80.60; H, 8.00%.
25
leum ether/ethyl acetate 10:1). Mp: 49–51 ꢁC. ½aꢂD :
3.2.9. (2R,5R)-2,5-Diphenylcyclopentane-1,1-
dicarbaldehyde (6)
1
ꢀ91.3ꢁ (c 1.206, EtOAc). H NMR (CDCl3): d 7.45–7.31
(m, 10H, HAr), 5.71–5.60 (m, 2H, CH), 2.67 (s, 6H,
CH3), 2.35–2.14 (m, 2H, CH2), 2.13–1.88 (m, 2H, CH2).
A solution of dry dimethyl sulfoxide (2.6 g, 33.4 mmol)
in dry dichloromethane (5 mL) was added dropwise at
ꢀ78 ꢁC to oxalyl chloride (2.1 mL, 16.7 mmol) in dry
dichloromethane (40 mL). After stirring for 30 min at this
temperature, 5 (2.1 g, 7.6 mmol) in dry dichloromethane
(10 mL) was added dropwise at a temperature of ꢀ78 to
ꢀ70 ꢁC. After stirring for 90 min at ꢀ65 ꢁC the mixture
was cooled to ꢀ78 ꢁC, triethylamine (5.4 g, 53.1 mmol)
was added slowly and the mixture was stirred for 30 min
at this temperature. The reaction mixture was allowed to
warm to room temperature over the course of one hour.
The reaction was terminated by addition of saturated
NH4Cl-solution (15 mL) and the two layers were separated.
The aqueous layer was extracted with CH2Cl2 (4 · 15 mL)
and the combined organic layers were washed with 2M
HCl (5 · 15 mL) and saturated NaCl-solution (1 ·
15 mL). The solution was dried over Na2SO4 and after fil-
tration the solvent was evaporated. The crude product
3.2.7. (2R,5R)-2,5-Diphenylcyclopentane-1,1-dicarbonic
acid diethyl ester (4)
To a suspension of NaH (1.05 g, 43.8 mmol) in dry THF
(170 mL) malonic acid diethyl ester (11.7 g, 73.0 mmol) and
15-crown-5 (0.07 g, 0.25 mmol) were added and the reaction
mixture was refluxed for 1 h. After cooling to room temper-
ature a solution of 3 (5.8 g, 14.6 mmol) in dry THF (60 mL)
was added dropwise and the mixture was stirred for 1 h at
room temperature and then refluxed for 5 h. After addi-
tional 18 h at room temperature the solvent was evaporated
and the residue was dissolved in water (100 mL) and ethyl
acetate (100 mL). The layers were separated and the organic
layer was extracted with ethyl acetate (4 · 50 mL). The com-
bined organic layers were washed with 1 N NaOH-solution
(5 · 50 mL) and saturated NaCl-solution (1 · 50 mL). The

1054
D. Domin et al. / Journal of Organometallic Chemistry 692 (2007) 1048–1057
was purified by bulb-to-bulb distillation to give colorless
crystals. Yield: 1.8 g (84%). Rf = 0.51 (petroleum ether/
dure described for 7b a colorless oil. Yield: 0.44 g (100%).
Rf = 0.77 (petroleum ether/ethyl acetate 10:1). H NMR
1
ethyl acetate 10:1). Bp: 80–85 ꢁC/0.03 mbar. Mp: 114–
(CDCl3): d 7.29 (s, 2H, CHN), 7.18–7.01 (m, 20H, HAr),
4.33–4.17 (m, 2H, CH), 4.02 (q, J = 6.7 Hz, 2H, CH),
2.23–2.10 (m, 4H, CH2), 1.24 (d, J = 6.7 Hz, 6H, CH3).
13C{1H} NMR (CDCl3): d 165.3 (d), 144.6 (s), 140.1 (s),
128.8 (d), 127.9 (d), 127.8 (d), 126.4 (d), 126.3 (d), 126.1
(d), 68.8 (d), 59.9 (s), 50.7 (d), 30.2 (t), 24.0 (q).
20
116 ꢁC. ½aꢂ : +183.9ꢁ (c 1.004, CH2Cl2). 1H NMR (CDCl3):
D
d 9.31 (s, 2H, CHO), 7.31–7.02 (m, 10H, HAr), 4.19–4.00
(m, 2H, CH), 2.39–2.04 (m, 4H, CH2). 13C{1H} NMR
(CDCl3): d 201.1 (d), 137.0 (s), 128.8 (d), 128.3 (d), 127.4
(d), 71.8 (s), 49.5 (d), 31.1 (t). Anal. Calc. for C19H18O2
(278.37): C, 81.99; H, 6.52. Found: C, 81.86; H, 6.68%.
3.2.13. N,N0-((2R,5R)-2,5-Diphenyl-1,1-cyclopentylidene-
dimethylidyne)bis((S)-a-(methoxymethyl)-
benzeneethanamine) (7d)
3.2.10. N,N0-((2R,5R)-2,5-Diphenyl-1,1-cyclopentylidene-
dimethylidyne)bis(2,6-dimethylbenzeneamine) (7a)
2,6-Dimethylaniline (0.33 g, 2.70 mmol),
6
(0.25 g,
(S)-a-(Methoxymethyl)benzeneethanamine
(0.30 g,
0.90 mmol), p-toluene sulfonic acid monohydrate (0.03 g,
0.18 mmol) and toluene (5 mL) was heated under reflux
over a Dean–Stark trap for 3 h. After cooling to room tem-
perature the solvent was evaporated and saturated
Na2CO3-solution (5 mL) and diethylether (5 mL) were
added to the residue. The mixture was stirred for 15 min,
the layers were separated and the water layer was extracted
with diethylether (4 · 5 mL). The combined organic layers
were washed with water (1 · 10 mL) and saturated NaCl
solution (2 · 10 mL). The solution was dried over Na2SO4,
filtered and the solvent was evaporated. The oily residue
was purified by column chromatography (petroleum
ether/diethylether 30:1) and recrystallization from metha-
nol to give colorless crystals. Yield: 0.30 g (69%).
1.80 mmol) and 6 (0.25 g, 0.90 mmol) gave analogously
to the procedure described for 7b a colorless oil. Yield:
0.52 g (100%). Rf = 0.24 (petroleum ether/ethyl acetate
1
10:1). H NMR (CDCl3): d 7.26–6.78 (m, 22H, HAr and
CHN), 4.14–3.95 (m, 2H, CH), 3.30–2.98 (m, 12H, CH3
and CH2 and CH), 2.70 (dd, J = 13.6 Hz, 5.0 Hz, 2H,
CH2), 2.47 (dd, J = 13.6 Hz, 7.3 Hz, 2H, CH2), 2.21–1.93
(m, 4H, CH2). 13C{1H} NMR (CDCl3): d 167.0 (d), 140.4
(s), 138.6 (s), 129.4 (d), 129.2 (d), 127.8 (d), 127.5 (d),
125.9 (d), 125.6 (d), 75.4 (t), 71.1 (d), 60.1 (s), 58.6 (q),
50.2 (d), 39.1 (t), 30.5 (t).
3.2.14. N,N0-((2R,5R)-2,5-Diphenyl-1,1-cyclopentylidene-
dimethylidyne)bis((R)-a-(methoxymethyl)-
benzeneethanamine) (7e)
Rf = 0.90 (petroleum ether/ethyl acetate 10:1). Mp: 174–
20
175 ꢁC. ½aꢂ : ꢀ227.9ꢁ (c 0.822, CH2Cl2). 1H NMR
(R)-a-(Methoxymethyl)benzeneethanamine
(0.30 g,
D
(CDCl3): d 7.56 (s, 2H, CHN), 7.37–7.25 (m, 4H, HAr),
7.24–7.02 (m, 6H, HAr), 6.90–6.70 (m, 6H, HAr), 4.50–
4.31 (m, 2H, CH), 2.49–2.11 (m, 4H, CH2), 1.77 (s, 12H,
CH3). 13C{1H} NMR (CDCl3): d 168.7 (d), 150.7 (s),
140.1 (s), 129.4 (d), 128.4 (d), 127.8 (d), 126.9 (d), 126.8
(s), 123.3 (d), 63.2 (s), 51.5 (d), 31.8 (t), 18.4 (q). Anal. Calc.
for C35H36N2 (484.69): C, 86.73; H, 7.49; N, 5.78. Found:
C, 86.57; H, 7.77; N, 5.76%.
1.80 mmol) and 6 (0.25 g, 0.90 mmol) gave analogously
to the procedure described for 7b a colorless oil. Yield:
0.52 g (100%). Rf = 0.24 (petroleum ether/ethyl acetate
1
10:1). H NMR (CDCl3): d 7.51–7.15 (m, 20H, HAr), 7.11
-6.95 (m, 2H, CHN), 4.40–4.17 (m, 2H, CH), 3.48–3.30
(m, 10H, CH3 and CH2), 3.24–2.98 (m, 4H, CH2 and
CH), 2.80 (dd, J = 13.3 Hz, 7.4 Hz, 2H, CH2), 2.35–2.02
(m, 4H, CH2). 13C{1H} NMR (CDCl3): d 167.2 (d), 140.2
(s), 139.2 (s), 129.5 (d), 128.9 (d), 128.0 (d), 127.7 (d),
125.9 (d), 125.8 (d), 75.2 (t), 71.2 (d), 60.2 (s), 58.6 (q),
50.5 (d), 39.2 (t), 30.3 (t).
3.2.11. N,N0-((2R,5R)-2,5-Diphenyl-1,1-cyclopentylidene-
dimethylidyne)bis((S)-a-methylbenzenemethanamine) (7b)
(S)-a-Methylbenzenemethanamine (0.22 g, 1.80 mmol),
6 (0.25 g, 0.90 mmol), and toluene (20 mL) was heated
under reflux over a Dean–Stark trap for 5 h. The solvent
was evaporated and the colorless oil was used without fur-
ther purification. Yield: 0.44 g (100%). Rf = 0.77 (petro-
3.3. Synthesis of the complexes
3.3.1. Pd{N,N0-(1,1-Cyclopentylidenedimethylidyne)bis-
((S)-a-methylbenzenemethanamine)}Cl2 (8a)
1
leum ether/ethyl acetate 10:1). H NMR (CDCl3): d 7.32
Compound 1a (400 mg, 1.20 mmol) was dissolved in
dichloromethane (5 mL) and added to a solution of
Pd(COD)Cl2 (342 mg, 1.20 mmol) in dichloromethane
(5 mL). After stirring for 2h at room temperature, the sol-
vent was removed under vacuum and the resulting yellow
solid was collected on a glass frit and washed twice with
diethylether (5 mL). Yield: 451 mg (88%). 1H NMR
(CD2Cl2): d 7.47–7.40 (m, 6H, HAr), 7.28–7.25 (m, 4H,
HAr), 7.09 (s, 2H, CHN), 5.77 (q, J = 6.7 Hz, 2H, CH),
2.93–2.68 (m, 4H, CH2), 1.83–1.76 (m, 4H, CH2), 1.40 (d,
J = 6.8 Hz, 6H, CH3). 13C{1H} NMR (CD2Cl2): d 170.2
(d), 139.0 (s), 129.1 (d), 128.7 (d), 128.3 (d), 66.3 (d), 60.2
(s, 2H, CHN), 7.28–7.10 (m, 10H, HAr), 7.05–6.87 (m,
10H, HAr), 4.23–4.09 (m, 2H, CH), 4.02 (q, J = 6.6 Hz,
2H, CH), 2.24–1.91 (m, 4H, CH2), 1.20 (d, J = 6.6 Hz,
6H, CH3). 13C{1H} NMR (CDCl3): d 165.5 (d), 145.4 (s),
140.2 (s), 128.9 (d), 128.1 (d), 127.8 (d), 126.6 (d), 126.5
(d), 126.1 (d), 69.3 (d), 59.8 (s), 51.2 (d), 30.5 (t), 24.7 (q).
3.2.12. N,N0-((2R,5R)-2,5-Diphenyl-1,1-cyclopentylidene-
dimethylidyne)bis((R)-a-methylbenzenemethanamine) (7c)
(R)-a-Methylbenzenemethanamine (0.22 g, 1.80 mmol)
and 6 (0.25 g, 0.90 mmol) gave analogously to the proce-

D. Domin et al. / Journal of Organometallic Chemistry 692 (2007) 1048–1057
1055
(s), 31.0 (t), 25.4 (t), 20.0 (q). Anal. Calc. for
C23H28Cl2N2Pd: C, 54.19; H, 5.54; N, 5.50. Found: C,
54.24; H, 5.46; N, 5.60%.
was added and the mixture was refluxed for 2 h. The sol-
vent was removed under vacuum and the resulting beige
solid was collected on a glass frit and washed twice with
Et2O (10 mL). Yield: 0.64 g (86%). Mp: decomp. >200–
1
3.3.2. Pd{N,N0-(1,1-Cyclopentylidenedimethylidyne)-
bis((R)-a-methylbenzenemethanamine)}Cl2 (8b)
204 ꢁC. H NMR (CDCl3): d 7.46–7.02 (m, 12H, HAr and
CHN), 5.90 (bs, 2H, CH), 2.99–2.45 (m, 2H, CH2), 2.02–
1.05 (m, 12H, CH2 and CH3). 13C{1H} NMR (CDCl3): d
169.7 (d), 138.9 (s), 129.2 (d), 128.7 (d), 128.4 (d), 67.5
(d), 60.4 (s), 29.7 (t), 25.5 (t), 20.2 (q). Anal. Calc. for
C23H28Br2N2Pd: C, 46.14; H, 4.71; N, 4.68. Found: C,
46.20; H, 4.66; N, 4.75%.
Pd(COD)Cl2 (213 mg, 0.75 mmol) and 1b (250 mg,
0.75 mmol) gave analogously to the procedure described
for 8a a yellow solid. Yield: 320 mg (84%). 1H NMR
(CD2Cl2): d 7.38–7.35 (m, 6H, HAr), 7.28–7.25 (m, 4H,
HAr), 7.08 (s, 2H, CHN), 5.79 (q, J = 6.7 Hz, 2H, CH),
2.69–2.66 (m, 4H, CH2), 1.83–1.77 (m, 4H, CH2), 1.40 (d,
J = 6.9 Hz, 6H, CH3). 13C{1H} NMR (CD2Cl2): d 170.1
(d), 139.0 (s), 129.1 (d), 128.7 (d), 128.3 (d), 66.3 (d), 60.1
(s), 39.6 (t), 25.4 (t), 20.0 (q). Anal. Calc. for
C23H28Cl2N2Pd: C, 54.19; H, 5.54; N, 5.50. Found: C,
54.30; H, 5.68; N, 5.47%.
3.3.6. Pd{N,N0-((2R,5R)-2,5-Diphenyl-1,1-
cyclopentylidenedimethylidyne)bis(2,6-dimethyl-
benzenamin)}Cl2 (9a)
A suspension of PdCl2 (62.1 mg, 0.35 mmol) in acetoni-
trile (6 mL) was refluxed until a clear orange solution of
Pd(CH3CN)2Cl2 was formed. 7a (0.17 g, 0.35 mmol) was
then added whereupon the color of the solution changed
from orange to yellow. After the mixture was refluxed
for 2 h, the solvent was removed under vacuum and the
resulting yellow solid was collected on a glass frit and
washed twice with Et2O (5 mL). Yield: 0.23 g (99%).
Mp: decomp. >240 ꢁC. 1H NMR (CDCl3): d 7.40–7.10
(m, 12H, HAr and CHN), 6.96–6.67 (m, 6H, HAr), 4.06
(bs, 2H, CH), 2.55–2.35 (m, 4H, CH2), 2.22 (s, 6H,
CH3), 1.34 (s, 6H, CH3). 13C{1H} NMR (CDCl3): d
172.1 (d), 148.7 (s), 136.2 (s), 129.8 (s), 129.7 (s), 129.5
(d), 128.5 (d), 128.3 (d), 127.8 (d), 127.7 (d), 126.8 (d),
67.0 (s), 56.3 (d), 31.2 (t), 19.6 (q), 17.7 (q). Anal. Calc.
for C36H36Cl2N2Pd: C, 64.15; H, 5.38; N, 4.16. Found:
C, 63.98; H, 5.12; N, 4.25%.
3.3.3. Pd{N,N0-(1,1-Cyclopentylidenedimethylidyne)-
bis((S)-a-(methoxymethyl)benzeneethanamine)}Cl2 (8c)
Pd(COD)Cl2 (270 mg, 0.95 mmol) and 1c (400 mg,
0.95 mmol) gave analogously to the procedure described
for 8a a yellow solid. Yield: 450 mg (80%). 1H NMR
(CD2Cl2): d 7.34–7.25 (m, 12H, HAr and CHN), 4.77 (bs,
2H, CH), 3.71 (dd, J = 10.7 Hz, 2.7 Hz, 1H, CH2), 3.57
(dd, J = 10.7 Hz, 4.8 Hz, 1H, CH2), 3.40 (dd,
J = 13.5 Hz, 6.4 Hz, 1H, CH2), 3.31 (s, 6H, OCH3), 2.92
(dd, J = 13.5 Hz, 9.1 Hz, 1H, CH2), 2.62–2.54 (m, 4H,
C(CH2CH2)2), 1.76–1.67 (m, 4H, C(CH2CH2)2). 13C{1H}
NMR (CD2Cl2): d 174.2 (d), 137.1 (s), 129.4 (d), 128.6
(d), 126.8 (d), 70.9 (t), 69.2 (d), 60.4 (s), 58.6 (q), 39.6 (t),
36.9 (t), 30.9 (t), 25.1 (t). Anal. Calc. for
C25H32Cl2N2O2Pd: C, 52.69; H, 5.66; N, 4.92. Found: C,
52.78; H, 5.56; N, 5.10%.
3.3.7. Pd{N,N0-((2R,5R)-2,5-Diphenyl-1,1-
cyclopentylidenedimethylidyne)bis((S)-a-
methylbenzenemethanamine)}Cl2 (9b)
3.3.4. Pd{N,N0-(1,1-Cyclopentylidenedimethylidyne)-
bis((R)-a(methoxymethyl)benzeneethanamine)}Cl2 (8d)
Pd(COD)Cl2 (170 mg, 0.60 mmol) and 1d (250 mg,
0.60 mmol) gave analogously to the procedure described
for 8a a yellow solid. Yield: 250 mg (70%). 1H NMR
(CD2Cl2): d 7.33–7.25 (m, 12H, HAr and CHN), 4.77
(bs, 2H, CH), 3.72 (dd, J = 10.7 Hz, 2.7 Hz, 1H, CH2),
3.57 (dd, J = 10.7 Hz, 4.6 Hz, 1H, CH2), 3.42 (dd,
J = 13.2 Hz, 6.4 Hz, 1H, CH2), 3.31 (s, 6H, OCH3),
2.92 (dd, J = 13.2 Hz, 8.9 Hz, 1H, CH2), 2.63–2.61 (m,
4H, C(CH2CH2)2), 1.76–1.67 (m, 4H, C(CH2CH2)2).
13C{1H} NMR (CD2Cl2): d 174.2 (d), 137.1 (s), 129.4
(d), 128.6 (d), 126.8 (d), 70.9 (t), 69.1 (d), 60.5 (s), 58.6
(q), 39.6 (t), 36.9 (t), 25.1 (t). Anal. Calc. for
C25H32Cl2N2O2Pd: C, 52.69; H, 5.66; N, 4.92. Found:
C, 52.61; H, 5.72; N, 4.87%.
PdCl2 (55.0 mg, 0.31 mmol) and 7b (0.15 g, 0.31 mmol)
gave analogously to the procedure described for 9a a
beige solid. Yield: 0.20 g (99%). Mp: decomp. >210 ꢁC.
1H NMR (CDCl3): d 7.50–7.11 (m, 16H, HAr and
CHN), 6.99–6.64 (m, 6H, HAr), 5.93–5.67 (m, 2H, CH),
4.42 (bs, 2H, CH), 2.82–2.35 (m, 4H, CH2), 1.19 (d,
J = 6.9 Hz, 6H, CH3). 13C{1H} NMR (CDCl3): d 166.9
(d), 138.0 (s), 137.5 (s), 128.9 (d), 128.6 (d), 128.4 (d),
128.3 (d), 127.8 (d), 127.7 (d), 67.3 (s), 66.8 (d), 54.5
(d), 29.9 (t), 19.5 (q). Anal. Calc. for C36H36Cl2N2Pd:
C, 64.15; H, 5.38; N, 4.16. Found: C, 64.20; H, 5.42;
N, 4.25%.
3.3.8. Pd{N,N0-((2R,5R)-2,5-Diphenyl-1,1-cyclo-
pentylidenedimethylidyne)bis((R)-a-methylbenzene-
methanamine)}Cl2 (9c)
3.3.5. Pd{N,N0-(1,1-Cyclopentylidenedimethylidyne)-
bis((R)-a-methylbenzenemethanamine)}Br2 (8e)
A suspension of PdBr2 (0.32 g, 1.23 mmol) in CH3CN
PdCl2 (72.7 mg, 0.41 mmol) and 7c (0.20 g, 0.41 mmol)
gave analogously to the procedure described for 9a a
beige solid. Yield: 0.27 g (99%). Mp: decomp. >120 ꢁC.
1H NMR (CDCl3): d 7.43–7.08 (m, 16H, HAr and
CHN), 7.07–6.80 (m, 6H, HAr), 5.85 (q, J= 6.7 Hz, 2H,
(20 mL) was refluxed until
a
clear solution of
Pd(CH3CN)2Br2 was formed. Then 1a (0.41 g, 1.23 mmol)

1056
D. Domin et al. / Journal of Organometallic Chemistry 692 (2007) 1048–1057
CH), 4.44 (bs, 2H, CH), 2.51–2.25 (m, 2H, CH2), 2.19–
1.88 (m, 2H, CH2), 1.18 (d, J = 7.0 Hz, 6H, CH3).
13C{1H} NMR (CDCl3): d 168.7 (d), 138.3 (s), 137.5 (s),
128.8 (d), 128.4 (d), 128.2 (d), 127.7 (d), 127.5 (d), 67.2
(s), 66.7 (d), 54.2 (d), 29.9 (t), 19.6 (q). Anal. Calc. for
C36H36Cl2N2Pd: C, 64.15; H, 5.38; N, 4.16. Found: C,
64.17; H, 5.26; N, 4.00%.
with the atoms to which they were bonded. For 8a the sol-
vent was disordered and was therefore squeezed with pro-
gram PLATON [21].
Acknowledgements
Financial support by the ‘‘Fonds zur Fo¨rderung der wis-
senschaftlichen Forschung’’ is gratefully acknowledged
(Project No. P16600-N11). D.B.-G. thanks the Basque
Government (Eusko Jaurlaritza/Gobierno Vasco) for a
doctoral fellowship.
3.3.9. Pd{N,N0-((2R,5R)-2,5-Diphenyl-1,1-
cyclopentylidenedimethylidyne)bis((S)-a-
(methoxymethyl)benzeneethanamine)}Cl2 (9d)
PdCl2 (35.5 mg, 0.20 mmol) and 7d (0.12 g, 0.20 mmol)
gave analogously to the procedure described for 9a a beige
solid. Yield: 0.12 g (80%). Mp: decomp. >105 ꢁC. 1H NMR
(CDCl3): d 7.49–7.01 (m, 22H, HAr and CHN), 4.98 (bs,
2H, CH), 4.48 (bs, 2H, CH), 3.39–2.60 (m, 14H, CH2
und CH3), 2.43–1.97 (m, 4H, CH2). 13C{1H} NMR
(CDCl3): d 171.9 (d), 138.3 (s), 136.5 (s), 129.0 (d), 128.8
(d), 128.6 (d), 127.7 (d), 126.8 (d), 71.0 (t), 67.9 (d), 60.9
(s), 58.4 (q), 54.6 (d), 37.1 (t), 29.9 (t). Anal. Calc. for
C37H40Cl2N2O2Pd: C, 61.55; H, 5.58; N, 3.88. Found: C,
61.78; H, 5.46; N, 3.70%.
Appendix A. Supplementary material
CCDC 618661, 618662, 618663 and 618664 contains the
supplementary crystallographic data for 7a, 8a, 9a and 9b.
These data can be obtained free of charge via htpp://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +(44) 1223-336-033; or e-
mail: deposit@ccdc.cam.ac.uk. Supplementary data associ-
ated with this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2006.10.064.
3.3.10. Pd{N,N0-((2R,5R)-2,5-Diphenyl-1,1-
cyclopentylidenedimethylidyne)bis((R)-a-
(methoxymethyl)benzeneethanamine)}Cl2 (9e)
References
PdCl2 (62.1 mg, 0.35 mmol) and 7e (0.20 g, 0.35 mmol)
gave analogously to the procedure described for 9a a beige
solid. Yield: 0.20 g (76%). Mp: decomp. >115 ꢁC. 1H NMR
(CDCl3): d 7.49–7.01 (m, 22H, HAr and CHN), 4.98 (bs,
2H, CH), 4.48 (bs, 2H, CH), 3.39–2.60 (m, 14H, CH2
und CH3), 2.43–1.97 (m, 4H, CH2). 13C{1H} NMR
(CDCl3): d 171.9 (d), 138.3 (s), 136.5 (s), 129.0 (d), 128.8
(d), 128.6 (d), 127.7 (d), 126.8 (d), 71.0 (t), 67.9 (d), 60.9
(s), 58.4 (q), 54.6 (d), 37.1 (t), 29.9 (t). Anal. Calc. for
C37H40Cl2N2O2Pd: C, 61.55; H, 5.58; N, 3.88. Found: C,
61.50; H, 5.38; N, 3.93%.
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