Cationic half-sandwich Ru(II) complexes bearing (S)-2-pyridyl-imino-[2.2] paracyclophane ligands: Synthesis, intramolecular and interionic structure

Article abstract of DOI:10.1016/j.jorganchem.2005.08.047

(S)-2-Pyridyl-imino-[2.2]paracyclophane ligands 1 and 2 were synthesized by a condensation reaction of 2-COR-C₅H₄N (1: R = H; 2: R = Me) with enantiopure (-)-S-amino-[2.2]-paracyclophane. The reactions of 1 and 2 with [Ru(η⁶-cymene)Cl(μ-Cl)]₂ afforded complexes [Ru(η⁶-cymene)Cl(N,N)]X (3: N,N = 1; 4: N,N = 2; X-=BPh4-,PF6-,BF4-) that were completely characterized in solution. For 4PF ₆ the solid state structure was determined by X-ray single-crystal diffractometric studies. Two diastereoisomers [(S_Ru, S_L) and (R_Ru, S_L)] were obtained in solution due to the presence of the planar chirality of paracyclophane (L) and the central chirality on ruthenium. ¹H-NOESY NMR experiments were used to determine the chirality of the metal center and, consequently, to identify (S_Ru, S_L) and (R_Ru, S_L) diastereoisomers. The cymene orientation, obtained by intramolecular ¹H-NOESY NMR investigations, and the relative anion-cation position, determined by interionic ¹H-NOESY or ¹⁹F,¹H-HOESY NMR studies, depended on the nature of the diastereoisomer.

Full text of DOI:10.1016/j.jorganchem.2005.08.047

Journal of Organometallic Chemistry 691 (2006) 165–173
www.elsevier.com/locate/jorganchem
Cationic half-sandwich Ru(II) complexes bearing
(S)-2-pyridyl-imino-[2.2]paracyclophane ligands: Synthesis,
intramolecular and interionic structure
Gianluca Ciancaleoni, Gianfranco Bellachioma, Giuseppe Cardaci, Giacomo Ricci,
*
Renzo Ruzziconi, Daniele Zuccaccia, Alceo Macchioni
`
Dipartimento di Chimica, Universita di Perugia, Via Elce di Sotto, 8 – 06123 Perugia, Italy
Received 11 May 2005; received in revised form 7 August 2005; accepted 24 August 2005
Available online 11 October 2005
Abstract
(S)-2-Pyridyl-imino-[2.2]paracyclophane ligands 1 and 2 were synthesized by a condensation reaction of 2-COR-C5H4N (1: R = H; 2:
R = Me) with enantiopure (ꢀ)-S-amino-[2.2]-paracyclophane. The reactions of 1 and 2 with [Ru(g6-cymene)Cl(l-Cl)]2 afforded com-
plexes [Ru(g6-cymene)Cl(N,N)]X (3: N,N = 1; 4: N,N = 2; Xꢀ ¼ BPh4ꢀ; PF6ꢀ; BFꢀ4 ) that were completely characterized in solution. For
4PF6 the solid state structure was determined by X-ray single-crystal diffractometric studies. Two diastereoisomers [(SRu,SL) and
(RRu,SL)] were obtained in solution due to the presence of the planar chirality of paracyclophane (L) and the central chirality on ruthe-
nium. 1H-NOESY NMR experiments were used to determine the chirality of the metal center and, consequently, to identify (SRu,SL) and
(RRu,SL) diastereoisomers. The cymene orientation, obtained by intramolecular 1H-NOESY NMR investigations, and the relative anion–
cation position, determined by interionic 1H-NOESY or 19F,1H-HOESY NMR studies, depended on the nature of the diastereoisomer.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Ruthenium compounds; N,N-paracyclophane ligands; 1H-NOESY and 19F,1H-HOESY NMR; X-ray structure; Ion-pairs
1. Introduction
clearly and quantitatively discriminated [5]. The aggrega-
tion level can be determined by PGSE (pulsed field gradient
spin-echo) techniques [6] that allow the average hydrody-
namic radius and volumes of the species present in solution
to be evaluated. In this context, a few half-sandwich Ru(II)
complexes containing N-ligands have been investigated
that show a remarkable tendency to aggregate in a variety
of aprotic and protic solvents even those with moderate to
high relative permittivity [7].
While [2.2]paracyclophane-based ligands are assuming a
growing importance in asymmetric organometallic catalysis
[8], they have rarely been used in reactions mediated by
ruthenium complexes [9,10]. In the few existing cases, bisph-
oshino-[2.2]paracyclophane ligands have been employed [9]
or the possibility of coordinating paracyclophane to the
metal in a g6-fashion has been utilized [10]. To the best of
our knowledge, only one ruthenium complex bearing a nitro-
gen paracyclophane ligand has been synthesized [11]. In
Half-sandwich ruthenium complexes bearing N,N-
ligands are currently used as catalysts for organic reactions
[1] and have recently been proposed as anticancer drugs [2].
In such applications a key role is played by weak interactions
that can affect their catalytic performances in terms of reac-
tion yield, chemio-, regio- and stereo-selectivity [3] and, in
the biomedical applications, the recognition phenomena [2].
Valuable information about the intermolecular interac-
tions in solution of transition-metal complexes can be ob-
tained by NMR techniques. In particular, if salts are
considered, the relative anion–cation orientations can be
deduced by NOE (nuclear Overhauser effect) experiments
[4]; orientations differing by less than 1 kcal/mol can be
*
Corresponding author. Tel.: +39 75 5855579; fax: +39 75 5855598.
E-mail address: alceo@unipg.it (A. Macchioni).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.08.047

166
G. Ciancaleoni et al. / Journal of Organometallic Chemistry 691 (2006) 165–173
addition, only a few transition metal complexes bearing
N,N-bidentate paracyclophane ligands have been previously
prepared [12] and applied in catalysis [13].
Arene ruthenium complexes with central chirality at the
metal center and central [14,15] or axial [16] chirality on
the ligand have been extensively studied by Brunner and
co-workers [17]. They deeply investigated the factors that
affect the intercorversion of the various diastereoisomers
in solution for several classes of ligands [18] including
pyridine imines deriving from the condensation of pyridine
2-aldehyde and 2-acetylpyridine and optically active amines
N
HCOOH
cat.
O
R
R
+
+
H2O
N
N
NH2
S
SL
1: R = H
2: R = Me
[16]. In addition, they showed that weak (arene)CHꢁ ꢁ ꢁ
X
Scheme 1.
interactions (X = electronegative substituent) play a key
role in determining 1:1 diastereoisomer co-crystallization
and crystallization as a pure diastereoisomer [19].
both complexes due to the presence of the planar chirality
of paracyclophane and central chirality of ruthenium
(Scheme 2). The ratio (SRu,SL)/(RRu,SL) was 1.9 and 0.6
for 3X and 4X, respectively, and did not depend on the
counterion. Anion methatesis of 3BPh4 and 4BPh4 with
AgBF4 afforded complexes 3 and 4 with BFꢀ4 counterion
without altering the diastereoisomeric ratio.
In this paper, we report the synthesis, intramolecular
and interionic characterization of the first half-sandwich
ruthenium complexes bearing an N,N-paracyclophane
ligand. The synthesized complexes possess a planar chirality
due to paracyclophane and a central chirality on ruthenium
that has four different substituents. Since S-enantiopure
paracyclophane ligands have been used, (SRu,SL) and
(RRu,SL) diastereoisomers (where L stands for paracyclo-
phane ligand) were obtained and identified in solution
through 1H-NOESY NMR studies. Furthermore, the
orientation(s) of cymene and the relative anion–cation posi-
tion(s) in solution were investigated by means of homo-
and hetero-NOE experiments for both diastereoisomers.
A point that has provoked some controversy in the liter-
ature was the determination of the stability or lability of
the metal configuration in chiral-at-metal half sandwich
compounds [18]. In compounds 3 and 4 the two diastereo-
isomers did not exhibit any tendency to interconvert as de-
duced by the independence of the diastereoisomeric ratios
of time and temperature and by the absence of exchange
NOE peaks in the 1H-NOESY NMR spectra. In fact,
NMR tubes containing diastereoisomeric mixtures of 3 or
4 were maintained in solution for two weeks and warmed
2. Results and discussion
1
up to the solvent boiling point without the H NMR spec-
2.1. Synthesis of ligands 1–2 and complexes 3–4
tra showing any significant alteration of the diastereoiso-
meric ratios. In addition, diastereoisomeric solutions
enriched in one diastereoisomer by means of fractional
2-Pyridyl-imino-(S)-[2.2]paracyclophane ligands 1–2
were synthesized by the condensation reaction of 2-pyridin-
ecarboxyaldehyde and 2-acetylpyridine with the enantio-
pure (ꢀ)-S-amino-[2.2]-paracyclophane, respectively, in
the presence of a catalytic amount of HCOOH (Scheme 1).
The reactions of 1 and 2 with the dimer [Ru(g6-cymene)-
Cl(l-Cl)]2 in methanol followed by the addition of a large
excess of NaBPh4 or NH4PF6 afforded complexes 3X and
4X (Xꢀ ¼ BPh4ꢀ or PFꢀ6 ), respectively (Scheme 2). Two dia-
stereoisomers [(SRu,SL) and (RRu,SL)] were obtained for
1
crystallization did not exhibit any modification in the H
NMR spectrum recorded at 298 K in CD2Cl2 after 24 h.
These observations lead one to conclude that the above-
mentioned ratios are likely kinetically determined and
compounds 3–4 are configurationally stable at the metal
in the investigated conditions.
Fractionated crystallizations allowed the major diaste-
reoisomer [(SRu,SL) and (RRu,SL) for complexes 3 and 4,
respectively] to be obtained in a pure form.
X-
Cl
N
+ MX
+
Ru
N
N
Cl
R
or
2
2
R
X-
+ 2
R
Ru
Ru
Cl
Ru
N
Cl
-2 MCl
N
N
Cl
Cl
SL
RRu,SL
SRu,SL
1: R = H
2: R = Me
3: R = H
4: R = Me
X- = BF4-, PF6-, or BPh4
-
Scheme 2.

G. Ciancaleoni et al. / Journal of Organometallic Chemistry 691 (2006) 165–173
167
2.2. Intramolecular characterization in solution
RRu,SL diastereoisomer
7
10
Cl
Cl
1
1
All compounds were characterized by H, 13C, 19F, H-
COSY, 1H-NOESY, 19F, 1H-HOESY, 1H,13C-HMQC and
1H,13C-HMBC NMR spectroscopies at 293 K in CD2Cl2.
Numbering of atoms for 4PF6 is shown in Chart 1.
The complete assignment of the 1H and 13C NMR reso-
nances of complexes 3–4 was obtained starting from H11,
whose signal had the highest frequency [20], H7, the only
septet, and H23, the only aromatic singlet, following the
scalar and dipolar connectivity in the 1H- or 1H,13C-COSY
and NOESY spectra, respectively. Data are reported in
Section 4.
H
6
+
5
H
+
3
Ru 2
Ru
6
5
H
2
H
H
3
N
N
N
10
R
11H
11
23
23
7
R
H
H
A
B
SRu,SL diastereoisomer
7
10
Cl
Cl
H
H
The orientation of cymene and the consequent distinc-
tion of H3 and H2 from H5 and H6, respectively, were
mainly deduced by analyzing the relative intensities of the
H11 NOEs with cymene protons. Two different situations
were encountered for (RRu,SL) or (SRu,SL) diastereoiso-
mers of complexes 3 and 4 (Scheme 3). For the (RRu,SL)
diastereoisomer, the NOE intensities followed the order:
H5/H11 ꢂ H6/H11 ꢃ H3/H11 ꢃ H2/H11. In addition,
given that a medium sized NOE was observed between
H7 and H11, while a H10/H11 NOE was not and since
H23 mainly interacted with H3, orientation A of cymene
reported in the left side of Scheme 3 must be predominant
in solution. The other orientation (B), that is thought to be
derived from the rotation of the cymene in A by an angle
slightly smaller than 180ꢁ, has to be present in order to
justify the observations that H2/H11 and H3/H11 weak
NOEs have the same intensities.
In the case of (SRu,SL) diastereoisomer, H2 and H3 res-
onances were superimposed but the intensity of H6/H11
NOE was more than twice that of H5/H11. At the same
time, the addition of the intensities of H5/H11 and H6/
H11 NOEs was equal to that of H3/H11 and H2/H11. Sim-
ilarly, the sum of the NOE intensities of H5–H6/H23 and
H2–H3/H23 was equal. Furthermore, H10/H11 and H7/
H11 contacts had comparable intensities. This clearly indi-
cates that conformers A and B, shown in Scheme 3, are
both present in solution in similar amounts. In this case,
orientations A and B differ only with respect to a cymene
rotation of 180ꢁ.
2
Ru
5
Ru
2
+
+
H
3
H
6
6
3
H
H
5
H
H
23
23
N
7
N
11
N
N
11
10
R
A
R
B
Scheme 3.
The steric factor appears to determine the stability of a
particular cymene orientation. In detail, the least hindered
region that would be ideal for ‘‘locating’’ i-Pr and Me
groups of cymene is on the top of the pyridine ring (Scheme
3). This definitely occurs in the (SRu,SL) diastereoisomer,
where this region is occupied by i-Pr or Me rather indiffer-
ently as indicated by the comparable abundance of A and
B orientations. On the contrary, in the (RRu,SL) diastereo-
isomer, the perfect orientation of the i-Pr or Me group on
the top of the pyridine ring appears unlikely since the other
one would come in contact with the methylene bridge
(CH2) of the paracyclophane moiety. Due to the fact that
the i-Pr/CH2 steric repulsion is higher than that of the
Me/CH2 one, the former is forced to rotate further away
from CH2. These considerations justify the main presence
in solution of the two orientations A and B (Scheme 3),
as deduced by NOE contacts. A results favored because
it allows the most hindered cymene group to be located
where there is more space. This, in fact, is the orientation
observed in the solid state for (RRu,SL)-4PF6 (see below).
Interestingly enough, the chirality of the metal center for
complexes 4 could be determined by a quantitative analysis
of the NOEs between H17 and H23, H30 and H31. In fact,
in the (RRu,SL) diastereoisomer H17 is almost equidistant
from all three protons and consequently three NOEs of
comparable intensities were expected. On the contrary,
H17 is closer to H30 in the diastereoisomer (SRu,SL) and
a stronger NOE contact was expected. These situations
were observed for the diasteroisomers of 4 complexes
whose chirality and, consequently, the diastereoisomeric
ratio was established.
8
7
32
9
3
1
4
6
29
30
28
2
5
33
19
27
25
20
+
10
Ru
31 26
11
N
N
18
21
Cl
12
15
16
23 22
13 14
17
24
A quantitative analysis of 1H-NOESY NMR spectra al-
lowed us to find a probe to determine the chirality of the
metal center also for complex 3PF6. In fact, H16 exhibited
-
PF6
Chart 1.

168
G. Ciancaleoni et al. / Journal of Organometallic Chemistry 691 (2006) 165–173
Table 1
a NOE with the aliphatic hydrogens of the paracyclophane
Relative NOE intensities (I) determined by arbitrarily fixing at 1 the
intensity of the NOE(s) between the cation resonances H11 and PF6ꢀ
only in the (SRu,SL) isomer (Fig. 1).
(SRu,SL)-3PF6
(RRu,SL)-4PF6
2.3. Interionic characterization in solution
I
f
I/f
I
f
I/f
Relative anion–cation orientations were investigated by
means of 1H,19F-HOESY ðXꢀ ¼ PFꢀ6 Þ and 1H-NOESY
ðXꢀ ¼ BPhꢀ4 Þ NMR experiments. The spectra were col-
lected at 293 K in CD2Cl2.
H2
H3
H5
H6
H7
H8
H9
H10
H11
H12
H13
H14
H16
H17
H23
H29
H30
0.39
0.15
0.857
0.857
0.46
0.18
0.56
0.38
0.857
0.857
0.65
0.44
0.59
0.857
0.69
0.14
0.22
0.34
0.42
1.00
0.46
0.24
0.68
0.61
0.857
2.00
2.00
0.16
0.11
0.17
0.21
1.17
0.54
0.28
0.79
0.71
The intensities of the NOE contacts for (SRu,SL)-3PF6
and (RRu,SL)-4PF6, normalized for the number of equiva-
lent protons through the parameter f = [nI Æ nS/(nI + nS)]
(nI = number of equivalent nuclei of the first type, that is
1H, nS = number of equivalent nuclei of the second type,
that is 19F) [21], are listed in Table 1. An analysis of the
intensities of the interionic NOEs pertinent to imino-pyr-
idyl protons allowed us to conclude that more than a single
relative anion–cation orientation was present. The follow-
ing intensity orders were found (Table 1): H11 > H14 ꢃ
H16 > H12 > H23 > H13, for (SRu,SL)-3PF6; H11 >
H12 > H14 > H23 > H17 > H13, for (RRu,SL)-4PF6. It ap-
pears difficult to locate the anion in a particular position
from which it can interact simultaneously with H11 and
H23 having, in addition, the smallest NOE contact with
H13. It is instead probable that the anion assumes two
positions: one close to H11 as observed in the solid state
for (RRu,SL)-4PF6 and the other close to the imino-moiety.
The relative intensities of the interionic NOEs reported in
Table 1 suggest that the former is more populated.
0.50
0.14
1.00
0.43
0.11
0.38
2.00
2.00
0.857
0.857
0.857
0.857
0.25
0.07
1.17
0.50
0.13
0.44
2.00
0.857
0.857
0.857
0.857
0.857
0.44
0.24
2.00
0.857
0.22
0.28
0.31
0.11
0.21
0.857
0.857
0.857
0.36
0.13
0.25
f equal to nI Æ nS/(nI + nS) (nI = number of equivalent nuclei of the first
type, that is 1H, nS = number of equivalent nuclei of the second type, that
is 19F), i.e., the factor that allows the number of equivalent nuclei to be
taken into account.
H6, H9 and H10 interacted with the counterion with the
following order of intensities: H5 > H6 > H9 > > H10
(Table 1, Fig. 2). In contrast, for (SRu,SL)-3PF6 all cymene
protons interacted with PF6ꢀ but, interestingly, the sum of
The interionic NOEs between PFꢀ6 and the cymene pro-
tons perfectly reflect the two different orientations of cym-
ene in (RRu,SL) or (SRu,SL) diastereoisomers illustrated
above (Scheme 3). In fact, in (RRu,SL)-4PF6 only H5,
-
PF
6
ppm
32i and 33i
33e
5.5
1
H
5.4
5.3
5.2
5.1
5.0
4.9
4.8
4.7
4.6
*
ppm
8.8
5
1
H
(RRu,S ) 16
L
6
8.7
(SRu,S ) 16
L
8.6
2
3
8.5
3.0
3.2
3.4
ppm
ppm
72
74
1
H
19
F
Fig. 1. A section of the 1H-NOESY NMR spectrum (400.13 MHz, 293 K,
CD2Cl2) for 3PF6 showing the interactions between 16 proton of only one
diastereoisomer (assigned to (SRu,SL)) and 32 and 33 paracyclophane
protons. ‘‘i’’ and ‘‘e’’ indicate protons that point toward and in the
opposite direction of the N,N-ligand, respectively.
Fig. 2. A section of the 19F,1H-HOESY NMR spectrum (376.65 MHz,
293 K, CD2Cl2) for 4PF6 showing the selective interactions of the anion
with 5 and 6 cymene protons. Only the resonances pertinent to the
(RRu,SL) diastereoisomer are labeled.
denotes the signal due to the
*
residual non-deuterated solvent.

G. Ciancaleoni et al. / Journal of Organometallic Chemistry 691 (2006) 165–173
169
the intensities of the H2 and H3 contacts was equal to that
of H5 and H6 (Table 1). The contacts of the counterion
with H7 and H10 also had comparable intensities (Table
1). All of the framework appears to be highly consistent:
in the case of (RRu,SL)-diastereoisomer, for which the cym-
ene orientation A is predominant, the anion, that is mainly
located close to H11, interacts exclusively with one side of
the cymene (Scheme 4). In contrast, the anion can equiva-
lently interact with the protons belonging to both sides of
the cymene in (SRu,SL) diastereoisomer which exhibit in
solution both A and B cymene orientations (Scheme 4).
RRu,SL diastereoisomer
2.4. Solid state structure of 4PF6
10
Cl
6
-
Two ORTEP views of compound 4PF6 are shown in
Fig. 3. The complex can be identified as a three-legged pia-
no stool complex with a pseudo-octahedral geometry in
which the arene ligand (cymene) occupies three adjacent
sites of the octahedron as in other similar complexes re-
ported in the literature [22].
PF6
+
5
Ru
N
N
9
R
H
The plane defined by C1RuC4, which bisects the cymene
ligand along the direction of its two para substituents
(methyl and isopropyl), and the plane defined by
N1RuN2 form an angle of 62.65ꢁ. The cymene assumes
an almost ideal staggered conformation with the methyl
substituent of the cymene ligand that points in the same
direction as Cl (Fig. 3). This cymene orientation corre-
sponds to orientation A of Scheme 3 that was found to
be predominant in solution.
SRu,SL diastereoisomer
7
10
Cl
Cl
-
-
2
5
PF6
PF6
+Ru
+Ru
3
6
N
N
N
N
10
7
R
R
Scheme 4.
C9
C8
C3
C1
C7
C2
C24
F2
C4
C5
F3
C22
C23
C10
C25
C6
N1
C21
C20
F6
P
Ru
N2
C19
F1
C11
F5
C31
C26
C18
C16
C15
C27
C28
C12
F4
C17
C33
C14
C30
C13
Cl
C29
C32
Cl
C6
N1
C1
Ru
C3
C5
C2
C4
N2
Fig. 3. Two ORTEP views (30% ellipsoid probability) of 4PF6.

170
G. Ciancaleoni et al. / Journal of Organometallic Chemistry 691 (2006) 165–173
The cymene plane, defined by the C1C3C5 atoms is bent
NMR spectra were measured on a Bruker DRX 400 spec-
1
of 57.84ꢁ with respect to the N1RuN2 plane. The paracyclo-
phane moiety shows a pseudo-perpendicular configuration
with respect to the pyridyl moiety. In fact, the angles
between the planes described by C19C22C26C29 (the four
atoms bound to the two ethyl groups) and those containing
N1RuN2 and the pyridyl moiety are 94.62ꢁ and 96.95ꢁ,
respectively. Furthermore, if we consider the average of
the two possible planes that described the paracyclophane
moiety, C18C20C21C23 and C27C28C30C31, they are bent at
about 153ꢁ with respect to the cymene plane, defined by
the C1C3C5 atoms (the methyl substituent of the cymene
ligand is on the same part of the paracyclophane moiety)
and are bent at about 63ꢁ with respect to the N1RuN2 plane.
The PFꢀ6 anion is positioned between the chloride ligand
and the pyridyl ring as illustrated in Fig. 3 (top) and ob-
trometer, using TMS as reference for H and 13C experi-
ments. NMR samples were prepared dissolving about
20 mg of compound in 0.5 ml of methylene chloride-d2.
Two-dimensional 1H-NOESY and 19F, 1H-HOESY spectra
were recorded with a mixing time of 500–800 ms. IR spectra
were measured at room temperature (CH2Cl2, NaCl cell) on
a FT-IR 1725 X Perkin–Elmer spectrophotometer. Optical
rotations were taken using a JASCO DIP-360 polarimeter.
4.2. Synthesis and characterization of 1
2.254 gof(ꢀ)-S-amino[2.2]paracyclophane(10.09 mmol),
1.8 mL of 2-pyridinecarboxaldehyde (18.92 mmol) and
0.05 mL of formic acid were added to 30 mL of methanol.
The resulting heterogeneous dispersion was kept under stir-
ring for 2 h, at the end of which the solid turned from white to
yellow. The solid was filtered off, washed with cold methanol
(2 · 5 mL) and crystallized from methanol in the refrigerator
at ꢀ18 ꢁC. The needle-shaped, bright yellow crystals were
dried under vacuum, yielding 1.840 g of (ꢀ)-S-Py–C(H)@
N–(C16H15) (1, 5.88 mmol, yield: 58.3 %). M.p. 137–
˚
served in solution. The P–Ru distance is of 5.597 A.
3. Conclusions
Cationic arene Ru(II) complexes 3 and 4 bearing (S)-2-
pyridyl-imino-[2.2]paracyclophane ligands, possessing both
planar chirality in the ligand and central chirality at the
metal, were synthesized and completely characterized in
25
138 ꢁC. ½aꢄD ¼ ꢀ371:8 (c = 0.77; CHCl3). IR (CH2Cl2,
cmꢀ1): 3016.2 (s), 2932.4 (s), 1588.2 (s, C@O), 1568.0 (m),
897,9 (m). 1H NMR (CD2Cl2, 293 K): d 8.69 (d,
J = 5.6 Hz, 1H, 11), 8.37 (d, J = 7.9 Hz, 1H, 14), 8.32 (s,
1H, 16), 7.87 (t, J = 7.5 Hz, 1H, 13), 6.79 (d, J = 7.8 Hz,
1H, 12), 6.82 (d, J = 6.9 Hz, 1H, 30), 6.57 (m, 4H, 20-21-
27-28), 6.39 (d, J = 6.9 Hz, 1H, 31), 6.06 (s, 1H, 23), 3.30
(m, 1H, 32i), 3.10 (m, 6H), 2.78 (m, 1H, 33e). 13C NMR
(CD2Cl2, 293 K): 158.0 (16), 155.7 (15), 149.8 (11), 149.0
(19), 141.8 (26), 140.6 (29), 139.4 (22), 137.1 (13), 136.3
(18), 135.0 (27 or 28), 133.8 (20 or 21), 133.2 (20 or 21),
132.3 (31), 132.1 (27 or 28), 130.2 (30), 125.2 (12), 124.9
(23), 121.7 (14), 35.1 (32), 35.7 (24 or 25), 35.4 (24 or 25),
33.0 (33). Anal. Calc. for C22H20N2: C, 84.58; H, 6.45; N,
8.97. Found: C, 85,20; H, 6.68; N, 8.12%.
1
solution and in the solid state. H-NOESY NMR experi-
ments were used to determine the chirality of the metal cen-
ter and cymene orientation in solution. 19F,1H-HOESY
NMR investigation allowed us to elucidate the interionic
structure, i.e., the relative anion–cation orientations, in
solution. The solid state structure of 4PF6 was obtained
through X-ray single crystal studies and compared from
intramolecular and interionic points of view with that in
solution. Anion mainly locates close to H11 in both diaste-
reoisomers. Arene orientation is determined by steric
factors and results to be sensitive to the nature of the dia-
stereoisomer. In (SRu,SL) diastereoisomer this corresponds
to orienting i-Pr (A) and Me (B) groups of cymene on the
top of the pyridine and the two orientations are equally
present in solution. In (RRu,SL) diastereoisomer, i-Pr and
Me steric interactions with the methylene bridge of the
paracyclophane slightly alter A and B conformations and
favor A over B.
4.3. Synthesis and characterization of 2
2.314 g of (ꢀ)-S-amino [2.2]paracyclophane (10.36 mmol),
2.5 mL of 2-acetylpyridine (26.28 mmol) and 0.05 mL of
formic acid were added to 30 mL of methanol. A heteroge-
neous dispersion was obtained, due to the low solubility of
the white amine, that was kept under stirring for 2 h, at the
end of which the solid turned from white to yellow. The solid
was filtered off and washed with cold methanol (2 · 5 mL).
The resulting yellow solid was crystallized from methanol
in the refrigerator at ꢀ18 ꢁC. Pale yellow crystals were dried
under vacuum, yielding 1.979 g of (ꢀ)-S-Py–C(Me)@N–
(C16H15) (2, 6.06 mmol, yield: 58.5 %). M.p. 197–199 ꢁC.
4. Experimental
4.1. General methods
All reactions were carried out in dry, oxygen-free nitro-
gen atmosphere, using standard Schlenk techniques. All
solvents were dried and purified by standard methods, that
is, sodium/benzophenone for diethyl ether, phosphorus
pentoxide for methylene chloride and calcium hydride for
methanol, and freshly distilled before use. All commercial
reagents were used as received, without any further purifica-
tion. Complex [Ru(g6-cymene)Cl(l-Cl)]2 [23] and (ꢀ)-S-
amino [2.2]paracyclophane [24] were prepared as reported
25
½aꢄD ¼ ꢀ484:0 (c = 0.96; CHCl3). IR (CH2Cl2, cmꢀ1):
3017.8 (s), 2931.7 (s), 1641.9 (s, C@O), 1587.9 (m), 897,7
(m). 1H NMR (CD2Cl2, 293 K): d 8.70 (d, J = 4.8 Hz,
1H, 11), 8.54 (d, J = 7.9 Hz, 1H, 14), 7.90 (t, J = 7.6 Hz, 1H,
13), 7.41 (t, J = 6.8 Hz, 1H, 12), 7.25 (d, J = 7.8 Hz, 1H,
30), 6.63 (d, J = 7.8 Hz, 1H, 27), 6.53 (d, J = 7.8 Hz, 1H,
1
in the literature. One- and two-dimensional H, 13C, 19F

G. Ciancaleoni et al. / Journal of Organometallic Chemistry 691 (2006) 165–173
171
1
28), 6.48 (d, J = 7.8 Hz, 1H, 20), 6.44 (m, 2H, 21 and 31),
5.62 (s, 1H, 23), 3.29 (m, 2H, 32i and 33i), 3.10 (m, 4H, 24e,
25 and 33e), 2.95 (m, 1H, 24i), 2.64 (m, 1H, 32e), 2.24 (s,
3H, 17). 13C NMR (CD2Cl2, 293 K): 164.6 (16), 157.6
(15), 148.9 (11), 148.9 (18), 140.9 (22), 140.3 (29), 139.4
(26), 136.7 (13), 135.0 (20), 133.7 (28), 133.0 (27), 132.4
(31), 131.9 (19), 130.0 (30), 128.9 (21), 126.1 (23), 125.1
(12), 121.7 (14), 35.8 (25), 35.4 (24), 34.3 (33), 33.3 (32),
16.9 (17). Anal. Calc. for C23H22N2: C, 84.63; H, 6.79; N,
8.58. Found: C, 84,90; H, 7.02; N, 8.08%.
NH4PF6 as precipitating agent. Yield : 80.4%. H NMR
(CD2Cl2, 293 K, (SRu,SL)) d: 8.85 (d, J = 5.1 Hz, 1H),
8.50 (s, 1H), 7.94 (m, 2H), 7.49 (m, 1H), 7.32 (br, 8H,
o-BPh4), 7.00 (t, J = 7.0 Hz, 8H, m-BPh4), 6.86 (7,
J = 7.1 Hz, 4H, p-BPh4), 6.69 (m, 4H), 6.48 (m, 2H), 6.37
(d, J = 8.1 Hz, 1H), 5.06 (br, 2H), 5.00 (d, J = 5.91 Hz,
1H), 3.01 (m, 8H), 2.42 (sept, J = 6.9 Hz, 1H), 1.92 (s,
3H), 0.93 (d, J = 7.0 Hz, 3H), 0.81 (d, J = 6.9 Hz, 3H).
Anal. Calc. for C56H54BClN2Ru: C, 74.54; H, 6.03; N,
3.10. Found: C, 74.71; H, 6.13; N, 3.00%.
4.4. Synthesis and characterization of 3PF6
4.6. Synthesis and characterization of 3BF4
0.1928 g of 1 (0.6171 mmol) and 0.1922 g of [Ru(g6-cym-
ene)Cl(l-Cl)]2 (0.3138 mmol) were added to 5 mL of meth-
anol. A heterogeneous dispersion was obtained, due to the
low solubility of the ligand, that was kept under magnetic
stirring for 4 h. A solution of NH4PF6 in methanol was
added drop by drop to the resulting solution. An orange so-
lid immediately precipitated. It was filtered off, washed with
cold methanol (2 · 1 mL), with n-hexane (2 · 3 mL) and
dried under vacuum, yielding 0.338 g of 3PF6
(0.4641 mmol, yield: 75.2%). 1H NMR (CD2Cl2, 293 K,
(SRu,SL)): d 9.33 (d, J = 5.6 Hz, 1H, 11), 8.67 (s, 1H, 16),
8.34 (d, J = 7.6 Hz, 1H, 14), 8.23 (t, J = 7.6 Hz, 1H, 13),
7.83 (t, J = 6.4 Hz, 1H, 12), 6.81 (m, 2H, 20 and 21), 6.71
(m, 3H, 23, 27 and 28), 6.62 (d, J = 8.4 Hz, 1H, 31), 6.45
(d, J = 8.0 Hz, 1H, 30), 5.36 (m, 2H, 2 and 3), 5.23 (d,
J = 6.0 Hz, 1H, 5), 5.06 (d, J = 6.0 Hz, 1H, 6), 3.32 (m,
24i and 33e), [25] 3.30 (m, 25i), 3.28 (m, 33i), 3.26 (m, 32e
or 25e), 3.17 (m, 24e, 32i and 33i), 3.09 (32e or 25e), 2.57,
(sept, J = 7.2 Hz, 1H, 7), 2.10 (s, 3H, 10), 1.03 (d,
J = 7.2 Hz, 3H, 9), 0.86 (d, J = 6.8 Hz, 3H, 8); 13C NMR
(CD2Cl2, 293 K) d: 164.17 (16), 155.94 (11), 155.72 (15),
149.42 (18), 142.53 (20), 140.64 (29), 140.01 (13), 139.13
(22), 136.80 (27 or 28), 135.69 (23), 133.90 (20 or 21),
133.70 (20 or 21), 133.03 (30), 130.30 (14), 129.73 (12),
129.57 (31), 128.20 (19), 125.78 (27 or 28), 107.33 (4),
102.27 (1), 87.26 (5 or 6), 87.01 (3), 86.90 (2), 86.10 (5 or
6), 36.57 (32), 35.23 (24), 35.04 (33), 31.79 (25), 31.23 (7),
22.39 (9), 21.35 (8), 18.60 (10); 19F NMR (CD2Cl2, 293 K)
71.21 mg of 1BPh4 (0.0789 mmol) and 16.31 mg of
AgBF4 (0.0838 mmol) were dissolved in methylene chlo-
ride. The mixture was kept under magnetic stirring for
2 h. The color of the mixture changed from orange to
brown, and AgBPh4, that precipitated from the solution
as a colorless solid, was filtered off through celite. The addi-
tion of n-hexane to the solution led to the product that was
crystallized from a (1:1) mixture of diethyl ether and
dichloromethane. The yellow powder was dried under vac-
uum, yielding 29.61 mg of 3BF4 (0.0442 mmol, yield: 56%).
1H NMR (CD2Cl2, 293 K, (SRu,SL)) d: 9.51 (d, J = 5.2 Hz,
1H), 8.80 (s, 1H), 8.34 (d, J = 7.6 Hz, 1H), 8.14 (t,
J = 8.0 Hz, 1H), 7.75 (t, J = 6.4 Hz, 1H), 6.64 (m, 7H),
5.79 (d, J = 6.0 Hz, 1H), 5.68 (d, J = 6.0 Hz, 1H), 5.11
(d, J = 6.0 Hz, 1H), 4.88 (d, J = 6.0 Hz, 1H), 2.93 (m,
8H) 2.12 (m, 4H), 0.83 (d, J = 6.8 Hz, 3H), 0.69 (d,
J = 6.8 Hz, 3H); 19F NMR (CD2Cl2, 293 K) d: ꢀ149.10
(br, 10BF4), ꢀ149.16 (br, 11BF4). Anal. Calc. for
C32H34BClF4N2Ru: C, 57.37; H, 5.12: N, 4.18. Found: C,
57.71; H, 5.23; N, 3.92%.
4.7. Synthesis and characterization of 4PF6
Complex 4PF6 was synthesized with the same procedure
used for 3PF6, starting with 2 instead of 1. Yield: 83.0%. 1H
NMR (CD2Cl2, 293 K, (RRu,SL)) d: 9.23 (d, J = 5.2 Hz,
1H, 11), 8.23 (t, J = 7.6 Hz, 1H, 13), 8.16 (d, J = 7.2 Hz,
1H, 14), 7.81 (t, J = 7.2 Hz, 1H, 12), 6.92 (dd,
J1 = 7.6 Hz, J2 = 7.8 Hz, 2H, 27–28), 6.73 (d, J = 8.0 Hz,
1H, 20), 6.60 (d, J = 8.0 Hz, 1H, 21), 6.54 (d, J = 8.4 Hz,
1H, 31), 6.47 (d, J = 8.4 Hz, 1H, 30), 6.40 (s, 1H, 23),
5.04 (d, J = 6.0 Hz, 1H, 6), 4.77 (d, J = 6.0 Hz, 1H, 2),
4.72 (d, J = 6.0 Hz, 1H, 3), 3.42 (m, 33i), 3.38 (m, 24e),
3.30 (m, 25i), 3.25 (m, 32i), 3.22 (s, 17), 3.18 (m, 33e),
3.17 (m, 32e), 3.08 (m, 24i), 3.02 (m, 25e), 2.46 (sept,
J = 7.2 Hz, 1H, 7), 2.10 (s, 3H, 10), 1.03 (d, J = 7.2 Hz,
3H, 9), 0.97 (d, J = 6.8 Hz, 3H, 8); 13C NMR (CD2Cl2,
293 K) d: 173.76 (16), 155.93 (11), 155.72 (15), 151.30
(18), 140.73 (29), 140.57 (22), 140.06 (13), 140.01 (26),
137.72 (20), 135.36 (19), 134.47 (22), 133.69 (27–28),
133.10 (27–28), 131.82 (30), 131.60 (31), 129.24 (12),
128.41 (14), 120.94 (23), 107.20 (4), 103.69 (1), 86.61 (3),
86.47 (5), 86.20 (6), 86.00 (2), 35.842, 35.44, 35.27, 35.13,
22.62 (9), 21.82, 19.89 (17), 18.84 (10), 14,29 (8); 19F
1
d: ꢀ72.67 (d, J = 762 Hz, 6F). H NMR (CD2Cl2, 293 K,
(RRu,SL)): d 9.26 (d, J = 5.4 Hz, 1H, 11), 8.75 (s, 1H, 16),
8.41 (d, J = 5.4 Hz, 1H, 14), 8.21 (t, J = 8.7 Hz, 1H, 13),
7.79 (t, J = 6.2 Hz, 1H, 12), 6.85 (m, 2H), 6.70 (m, 3H),
6.56 (m, 2H), 5.71 (d, J = 6.0 Hz, 1H, 5), 5.30 (d,
J = 6.2 Hz, 1H, 6), 5.17 (d, J = 6.0 Hz, 1H, 2), 5.02 (d,
J = 5.9 Hz, 1H, 3), 3.18 (m, 6H), 2.96 (m, 1H), 2.86 (m,
1H), 2.36 (sept, J = 6.7 Hz, 1H, 7), 2.15 (s, 3H, 10), 0.99
(d, J = 6.9 Hz, 3H, 8 or 9), 0.95 (d, J = 6.9 Hz, 3H, 8 or
9). Anal. Calc. for C32H34ClF6N2PRu: C, 52.79; H, 4.71;
N, 3.85. Found: C, 53.04; H, 4.92; N, 3.55%.
4.5. Synthesis and characterization of 3BPh4
Complex 3BPh4 was synthesized with the same proce-
dure as that used for 3PF6, adding NaBPh4 instead of

172
G. Ciancaleoni et al. / Journal of Organometallic Chemistry 691 (2006) 165–173
1
NMR (CD2Cl2, 293 K) d: ꢀ73.16 (d, J = 755.6, 6F). H
NMR (CD2Cl2, 293 K, (SRu,SL)) d: 9.29 (d, J = 5.6, 1H,
14), 8.25 (t, J = 8.0, 1H, 12), 8.19 (d, J = 7.6, 1H, 11),
7.84 (t, J = 6.8, 1H, 13), 6.98 (dd, J1 = 7.6, J2 = 11.4,
2H, 27–28), 6.78 (d,J = 7.2, 1H, 20), 6.66 (d, J = 8.0, 1H,
31), 6.61 (d, J = 7.6, 1H, 21), 6.44 (d, J = 8.8, 1H, 30),
6.29 (s, 1H, 23), 5.50 (d, J = 6.0, 1H, 2), 5.41 (d, J = 6.4,
1H, 5), 5.05 (d, J = 6.4, 1H, 3), 4.87 (d, J = 6.4, 1H, 6),
3.221 (m, 8H), 2.65 (sept, J = 7.2, 1H, 7), 1.56 (s, 3H,
10), 1.02 (d, J = 7.2, 3H, 9), 0.82 (d, J = 6.8, 3H, 8). Anal.
Calc. for C33H36ClF6N2PRu: C, 53.41; H, 4.89; N, 3.77.
Found: C, 53.6; H, 5.21; N, 3.50%.
SALIS (CCD 169) software. The crystal-to-detector dis-
tance was 65.77 mm. The structure was solved using
direct methods and refined against |F|2. The Laue symmetry
was determined to 1.541 g cmꢀ3 (Z = 2 and FW = 742.13)
and the investigation of the observed systematic absences
are consistent with the monoclinic space group P21 (no. 4).
The data were collected at room temperature. The lattice
parameters found were: a = 8.015(1), b = 14.316(1) and
3
˚
˚
c = 14.349(1) A, b = 103.750(10)ꢁ, and V = 1599.3(3) A .
Data were collected to 2hmax of 57.20ꢁ in the index ranges
ꢀ5 6 h 6 10, ꢀ18 6 k 6 19, and ꢀ19 6 l 6 18 with a total
of 11372 reflections collected, of which 53 were rejected
and 7263 were unique reflections, independent Rint
=
˚
4.8. Synthesis and characterization of 4BPh4
0.0178, up to a resolution of 0.74 A. The frames were then
processed using the CRYSALIS (RED 169) software to
give the hkl file corrected for scan speed, background,
and Lorentz and polarization affects. Standard reflections,
measured periodically, showed no apparent variation in
intensity during data collection and so, no correction for
crystal decomposition was necessary. The data were cor-
rected for absorption using the SADABS [26] program. The
structure was solved by the direct method using the SIR97
[27] program and refined by the full-matrix least-squares
method on F2 using the SHELXL-97 [28], WinGX [29] version.
All non-hydrogen atoms were refined anisotropically. The
hydrogen atoms were added at the calculated positions
and refined using a riding model. The final cycle of full-
matrix least-squares refinement against |F|2 was based on
6116 observed reflections [F0 > 4 r (F0)] and 404 variable
parameters and converged with unweighted and weighted
Complex 4BPh4 was synthesized with the same proce-
dure used for 4PF6, using NaBPh4 instead of NH4PF6 as
precipitating agent. Yield: 83.5%. 1H NMR (CD2Cl2,
293 K, (RRu,SL)) d: 8.88 (d, J = 4.8 Hz, 1H), 7.97 (t,
J = 8.0 Hz, 1H), 7.70 (d, J = 7.6 Hz, 1H), 7.54 (t, J =
6.4 Hz, 1H), 7.39 (br, 8H, o-BPh4), 7.06 (t, J = 7.6 Hz,
8H, m-BPh4), 6.97 (m, 2H), 6.92 (br, 4H, p-BPh4), 6.71
(d, J = 8.0 Hz, 1H), 6.59 (d, J = 7.2 Hz, 1H), 6.48 (d,
J = 8.0 Hz, 1H), 6.21 (s, 1H), 5.13 (d, J = 6.0 Hz, 1H),
4.88 (d, J = 6.0 Hz, 1H), 4.59 (d, J = 6.0 Hz, 1H), 4.47
(d, J = 6.0 Hz, 1H), 3.21 (m, 8H), 2.89 (s, 3H), 2.34 (sept,
J = 6.8 Hz, 1H), 2.05 (s, 3H), 0.99 (d, J = 6.8 Hz, 3H),
0.89 (d, J = 6.8 Hz, 3H). Anal. Calc. for C57H56BClN2Ru:
C, 74.71; H, 6.16; N, 3.06. Found: C, 75.02; H, 6.40; N,
2.87%.
agreement factors of R = 0.0366 and Rw = 0.0767, and
2
4.9. Synthesis and characterization of 4BF4
GOF = 1.030
(w ¼ 1=½r2ðF 2oÞ þ ð0:0357PÞ þ 0:0000Pꢄ,
where P ¼ ðF 2o þ 2F 2cÞ=3).
Complex 4BF4 was synthesized with the same procedure
used for 3BF4, starting with 4BPh4 instead of 3BPh4. Yield:
5. Supplementary material
1
54.0%. H NMR (CD2Cl2, 293 K, (RRu,SL)) d: 9.31 (d,
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic Data
Center, CCDC No. 269352. Copies of this information
may be obtained free of charge from The Director, CCDC,
12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44 1223
336 033; e-mail: deposit@ccdc.cam.ac.uk or www.ccdc.
cam.ac.uk/data_request/cif).
J = 5.2 Hz, 1H), 8.23 (t, J = 8.0 Hz, 1H), 8,17 (d,
J = 8.0 Hz, 1H), 7.84 (t, J = 6.4 Hz, 1H), 6,91 (br, 2H),
6.72 (d, J = 7.6 Hz, 1H), 6.59 (d, J = 7.2 Hz, 1H), 6.53
(d, J = 8.0 Hz, 1H), 6.47 (d, J = 8.4 Hz, 1H), 6.41 (s,
1H), 5.40 (d, J = 6.0 Hz, 1H), 5.07 (d, J = 6.0 Hz, 1H),
4.76 (t, J = 6.8 Hz, 2H), 3.24 (m, 11H), 2.44 (sept,
J = 7.2 Hz, 1H), 2.09 (s, 3H), 1.02 (d, J = 6.8 Hz, 3H),
0.96 (d, J = 7.2 Hz, 3H). 19F NMR (CD2Cl2, 293 K) d:
ꢀ149.09 (br, 10BF4), ꢀ149.15 (br, 11BF4). Anal. Calc. for
C33H36BClF4N2Ru: C, 57.95; H, 5.31; N, 4.10. Found: C,
58.3; H, 5.54; N, 3.90%.
Acknowledgments
`
We thank the Ministero dellꢀIstruzione, dellꢀUniversita e
della Ricerca (MIUR, Rome, Italy), Programma di Rilev-
ante Interesse Nazionale, Cofinanziamento 2004–2005 for
support.
4.10. X-ray crystallography
A single crystal of 4PF6 suitable for X-ray diffraction (a
red block with approximate dimensions of 0.20 mm ·
0.15 mm · 0.10 mm) was obtained by crystallization from
methyl alcohol and diethyl ether. Data were collected on
a XCALIBUR (Kuma4CCD) diffractometer using Mo
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