One-pot synthesis of the new dianionic ligand [Na]2[C 5H4CO2(CH2)2NTs]; preparation and structures of two rhodium derivatives

Article abstract of DOI:10.1016/j.jorganchem.2004.10.024

The new dianionic ligand [Na]₂[C₅H₄CO ₂(CH₂)₂NTs] (1) having an alkoxycarbonyl and an amide group in the same side chain has been prepared by a single step, high yield procedure. The synthesis of the related rhodium complexes [Rh{η⁵-C₅H₄CO₂(CH ₂)₂N(H)Ts}(NBD)] (3) and [Rh{η⁵-C ₅H₄CO₂ (CH₂)₂N(Me)Ts} (NBD)] (4) is reported as well as their X-ray molecular structures.

Full text of DOI:10.1016/j.jorganchem.2004.10.024

Journal of Organometallic Chemistry 690 (2005) 818–824
www.elsevier.com/locate/jorganchem
One-pot synthesis of the new dianionic
ligand [Na]2[C5H4CO2(CH2)2NTs]; preparation and structures of
two rhodium derivatives
a,
a
a
b,
*
Luigi Busetto *, M. Cristina Cassani , Rita Mazzoni , Vincenzo G. Albano
,
b
Piera Sabatino
a
Dipartimento di Chimica Fisica ed Inorganica, viale Risorgimento 4, I-40136 Bologna, Italy
b
Dipartimento di Chimica ‘‘G. Ciamician’’, via Selmi 2, I-40126 Bologna, Italy
Received 27 August 2004; accepted 12 October 2004
Abstract
The new dianionic ligand [Na]2[C5H4CO2(CH2)2NTs] (1) having an alkoxycarbonyl and an amide group in the same side chain
has been prepared by a single step, high yield procedure. The synthesis of the related rhodium complexes [Rh{g5-
C5H4CO2(CH2)2N(H)Ts}(NBD)] (3) and [Rh{g5-C5H4CO2 (CH2)2N(Me)Ts}(NBD)] (4) is reported as well as their X-ray molecular
structures.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Cyclopentadienyl ligands; Oxazolidin-2-ones; Rhodium complexes; X-ray diffraction
1. Introduction
half-sandwich complex. In any case at least three reac-
tion steps are required [2a,b].
In the late 1980s, Bercaw and Shapiro [1] introduced
the first complexes of a dianionic bridged amido-cyclo-
pentadienyl ligand system [A]2ꢀ (in Chart 1). Since then
a variety of Cp/amide ‘‘constrained geometry’’ ligands,
derived from the parent compound [A]2ꢀ, have become
known and Chart 1 shows some representative examples
[2].
All the dianionic ligands of the type reported in Chart
1 have been prepared with stepwise methods typically
including purification of the intermediate products by
distillation or sublimation. For instance, the synthesis
of A can be accomplished using different routes: starting
from the Cp fragment, from the amine NH2R2 or by
introducing the amido linkage within the preformed
We have recently shown that the reaction of NaCp
with aliphatic five-membered cyclic carbonates leads, in
one step and high yields, to the selective formation of no-
vel chiral and non-chiral hydroxy-functionalised alkoxy-
carbonylcyclopentadienides Na[C5H4CO2(CHR)2OH]
(R = H, Me, Ph) without formation of any by-product
[3a–e]. These functionalised Cp ligands provided a valu-
able route to novel sandwich and half-sandwich metal
complexes and among these the rhodium derivatives
[Rh{g5-C5H4CO2(CHR)2OH}(L,L)] [R = H, Me, Ph;
L,L = 2 CO, NBD] exhibited catalytic activity in the
homogeneous hydroformylation and hydrogenation of
hex-1-ene and styrene [3c–e].
In addition, the presence in the lateral chain of the Cp
ligand of an hydroxyl functionality has been exploited to
develop a new route for anchoring the rhodium com-
plexes on the surface of polypropylenimine dendrimers
DAB-dendr-(NH2)n {n = 4, 8, 16, 32, 64} leading to
*
Corresponding authors. Tel.: +1 39 051 2093694, fax: +1 39 051
2093690.
E-mail address: busetto@ms.fci.unibo.it (L. Busetto).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.10.024

L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 818–824
819
R1R2
Si
This undesired result nevertheless indicated that a mol-
ecule in which the nitrogen atom is bound to a func-
tional group not susceptible to undergo a nucleophilic
attack by the Cpꢀ could be a promising candidate for
our target molecule. Indeed, treatment of two equiva-
lents of NaCp with one equivalent of 3-tosyl-oxazoli-
din-2-one in THF at room temperature for 24 h finally
led to the one-step, high yield synthesis of the new dian-
ionic cyclopentadienyl ligand [Na]2[C5H4CO2(CH2)2-
NTs] (1) containing an alkoxycarbonyl and an amide
group in the same side chain
NR2
NSiMe3
(-)
(-)
(a)
(b)
R = alkyl or aryl
R1R2
C
(CH2)n
NR3
(-)
NCH3
(-)
R4
(c)
(d)
Chart 1.
O
Ts
THF, r.t., 24 h
O
N
2NaCp +
the quantitative formation of new, completely function-
alised, organometallic macromolecules containing up to
64 peripheral alkoxycarbonylcyclopentadienyl com-
plexes of rhodium(I) [4].
These results made us wonder if it were possible to
apply the same procedure to five-membered cyclic oxaz-
olidin-2-ones. In this paper, we report the reaction of
NaCp with oxazolidin-2-ones and describe the one-step,
high yield synthesis of the new dianionic cyclopentadie-
nyl ligand [Na]2[C5H4CO2(CH2)2NTs] (1) having an alk-
oxycarbonyl and an amide group on the same side
chain. The synthesis and structure of related rhodium
complexes is also described.
ð2Þ
O
N
(-) Na+
O
+ C5H6
Na+
Ts
1 (91%)
The regioselective ring-opening reaction is likely to
proceed via the formation of the 1-substituted cyclo-
pentadiene intermediate [Na][C5H5CO2(CH2)2NTs]
that, unlike what found with cyclic carbonates, is not
intramolecularly deprotonated by the amide arm but
by a second molecule of NaCp. After work-up, the
dianionic ligand 1 was obtained in yields higher than
90% as an air- and moisture-sensitive beige solid solu-
ble in THF.
2. Results and discussion
1
2.1. Synthesis and characterization of
[Na]2[C5H4CO2(CH2)2NTs] (1)
The H NMR spectrum in [D5]Pyr showed for the
Cp ring protons two AA0BB0 pseudotriplets at d 7.36
and 6.60 whilst in the 13C NMR the Cp signals were
found in the range d 113–109, very similar to what al-
ready reported for Na[C5H4CO2(CHR)2OH] (R = H,
Me, Ph) [3b–e]. The methylene protons of the anionic
pendant side chain exhibited two triplets at d 4.61
(CO2CH2) and 3.52 (CH2N) with corresponding reso-
nances in the 13C NMR at d 64.5 and 46.6. The IR
spectra of 1 in THF showed a (C@O) broad band
The initial observations that NaCp does not react with
3-methyl-oxazolidin-2-one or 3-trimethylsilyl-oxazoli-
din-2-one led us to consider systems with a nitrogen bear-
ing an electron withdrawing group. In this direction, the
first attempt with the commercially available 3-acetyl-
oxazolidin-2-one resulted in the formation of the already
known acetylcyclopentadienyl sodium Na[C5H4COCH3]
[5] together with the oxazolidin-2-one sodium salt and
cyclopentadiene with an overall reaction stoichiometry
shown in Eq. (1) (see also Section 3).
around 1635 cmꢀ1
.
2.2. Synthesis and molecular structure of
[Rh{g5-C5H4CO2(CH2)2N(H)Ts}(NBD)] (3) and
[Rh{g5-C5H4CO2(CH2)2N(Me)Ts}(NBD)] (4)
O
O
THF, r.t., 24 h
O
N
In order to get further evidences of the dianionic nat-
ure of 1, we reacted it with [Rh(NBD)Cl]2 in THF at
room temperature. The reaction readily led to the quan-
titative formation (established by NMR of the crude
reaction mixture) of [Na][Rh{g5-C5H4CO2(CH2)2-
NTs}(NBD)] (2) that for further treatment either with
a proton acidic solvent such as dichloromethane or
MeI, respectively, gave, after chromatography, the
2NaCp +
O
O
O
N(-) Na+
+
+ C5H6
Na+
ð1Þ

820
L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 818–824
O
N(-) Na+
O
Ts
THF, r.t., 3 h
Rh
1
+ [Rh(NBD)Cl]2
2
O
O
NMe
Ts
NH
Ts
O
O
Rh
Rh
3 (82%)
4 (77%)
Scheme 1.
neutral yellow, air-stable complexes [Rh{g5-C5H4CO2-
(CH2)2N(H)Ts}(NBD)] (3) and [Rh{g5-C5H4CO2-
(CH2)2N(Me)Ts}(NBD)] (4) (Scheme 1).
C22
C19
The two rhodium complexes 3 and 4 have been fully
characterised by standard analytical/spectroscopic
measurements. The NMR spectra in CDCl3 of the com-
plexes depicted in Scheme 1 showed the resonances for
the C5H4- and NBD moieties, which are strictly compa-
rable with those of the previously reported [Rh{g5-
C5H4CO2(CH2)2OH}(NBD)] [3b].
Crystallization from CH2Cl2/Etp by the diffusion
method yielded for both 3 and 4 single crystals that
were characterised by X-ray diffraction. The molecular
structures, as found in the crystals, are shown in Fig. 1
for 3 and Fig. 2 for 4, relevant bond parameters are
comparatively listed in Table 1. In order to make com-
parisons easier, the molecular drawings adopt almost
equivalent points of view for the C5H4COO planar
fragments.
C20
C21
C18
C17
C8
C9
C12
C16
C6
O3
C7
C10
O4
C11
S1
N1
Rh
C3
C15
C14
C2
O2
C13
C4
C1
C5
O1
Fig. 1. Molecular structure of [Rh{C5H4CO2 (CH2)2N(H)Ts}(NBD)]
(3) showing the atomic numbering (thermal ellipsoids at 50% prob-
ability level). For the sake of clarity, only one image of the disordered
side chain is shown.
Concerning 3, the geometry of coordination around
Rh is quite regular and the NBD molecule and
C5H4COO fragment are mutually oriented in a quasi
Cs symmetry. The side chain deprives the molecule of
any symmetry and the crystal contains two randomly
packed isomers of almost equivalent overall hindrance
and shape. The disorder is seemingly generated by the
fact that molecules of opposite configuration at the
N(1) chiral centre fail to pack in an orderly way. In fact,
the flexibility of the chain is able to confer comparable
shape to the enantiomers.
The crystal of 4 contains an ordered packing of two
isomers labelled I and II in Fig. 2. The coordination
geometry around Rh, apart from a slightly different ori-
entation of the NBD ligand, is substantially similar in
the two isomers and 3. However, significant differences
are present in the side chains, starting from the point
of attachment to the carboxylate oxygens. With refer-
ence to Fig. 2, C(14) is attached to the rear oxygen in
molecule I, as in 3, and to the front oxygen in molecule

L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 818–824
821
Table 1
Significant bond distances (A) for 3 and 4
C8
˚
O4
C9
C10
C17 C18
3
4
I
C12
C6
C7
O3
C16
S1
C22
II
C11
C19
C20
C21
C23
Rh–C(1)
Rh–C(2)
2.237(2)
2.244(2)
2.304(2)
2.303(2)
2.229(2)
2.134(2)
2.122(2)
2.118(2)
2.135(2)
1.430(3)
1.425(3)
1.420(3)
1.414(3)
1.421(3)
1.415(3)
1.533(3)
1.544(3)
1.541(3)
1.537(3)
1.407(3)
1.531(3)
1.535(3)
1.463(3)
1.210(3)
1.351(3)
1.445(3)
1.542(4)a
1.460(4)a
1.630(4)a
2.263(5)
2.193(6)
2.271(5)
2.293(6)
2.262(5)
2.106(6)
2.091(7)
2.105(7)
2.126(6)
1.429(4)
1.427(4)
1.425(4)
1.424(4)
1.422(4)
1.413(5)
1.538(5)
1.540(5)
1.545(5)
1.536(5)
1.400(5)
1.534(5)
1.534(5)
1.465(4)
1.209(5)
1.355(6)
1.453(5)
1.511(6)
1.474(5)
1.651(4)
1.467(5)
1.424(3)
1.439(3)
1.758(2)
2.276(5)
2.270(6)
2.270(6)
2.267(6)
2.249(6)
2.129(8)
2.134(7)
2.154(8)
2.167(8)
1.425(4)
1.435(4)
1.423(4)
1.418(4)
1.423(4)
1.407(5)
1.535(5)
1.539(5)
1.547(5)
1.531(5)
1.390(5)
1.546(5)
1.543(5)
1.465(4)
1.212(4)
1.358(5)
1.450(5)
1.523(6)
1.479(5)
1.655(4)
1.467(5)
1.435(3)
1.431(4)
1.758(3)
N1
Rh
C3
Rh–C(3)
Rh–C(4)
C2
O2
C15
C14
C13
C1
C4
Rh–C(5)
Rh–C(6)
Rh–C(7)
C5
O1
molecule I
Rh–C(10)
Rh–C(11)
C(1)–C(2)
C(1)–C(5)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(6)–C(7)
C(7)–C(9)
C(8)–C(9)
C(8)–C(12)
C(9)–C(10)
C(10)–C(11)
C(6)–C(12)
C(11)–C(12)
C(1 )–C(13)
C(13)–O(1)
C(13)–O(2)
C(14)–O(2)
C(14)–C(15)
N(1)–C(15)
N(1)–S(1)
N(1)–C(23)
S(1)–O(3)
S(1)–O(4)
S(1)–C(16)
a
C8
C12
C9
C7
O4
C18
C6
C11
C17
C21
O3
C10
C22
C19
C16
C20
S1
Rh
C3
N1
O1
C2
C1
C15
C23
C14
C13
O2
C4
C5
molecule II
Fig. 2. Absolute structures of the two isomers (I and II) of
[Rh{C5H4CO2(CH2)2N(CH3)Ts}(NBD)] (4) found in the crystal
(thermal ellipsoids at 50% probability level).
II. A second relevant difference is that the absolute con-
figuration at N(1) is S in I and R in II. In spite of these
structural variations, the p-tolyl groupings are similarly
oriented in I and II. Their positioning is quite different
from that found in 3. There is no spectroscopic evidence
(NMR) of the persistence of isomeric forms in solution
at least down to ꢀ80 ꢁC.
1.432(4)a
1.428(4)a
1.761(3)a
Average value.
complexes using a WATERS ZQ 4000 mass spectrome-
ter. GC–MS analyses were run on a chromatograph fit-
ted with a 25-m capillary column (5% phenyl methyl
silicone) and a quadrupolar detector working at 70 eV.
Elemental analyses were performed on a ThermoQuest
Flash 1112 Series EA Instrument. The reagent 3-ace-
tyl-oxazolidin-2-one (Aldrich) was recrystallised from
Et2O, 3-tosyl-oxazolidin-2-one was prepared according
to the literature procedures [6]; [Rh(NBD)Cl]2 was used
as purchased, MeI was distilled under argon and stored
on molecular sieves. Petroleum ether (Etp) refers to a
fraction of b.p. 60–80 ꢁC. Column chromatography
were carried out on silica gel previously heated at about
200 ꢁC while a slow stream of a dry nitrogen was passed
through it [7]. Melting points were taken in sealed cap-
illaries and were uncorrected.
3. Experimental section
3.1. Materials and procedures for the syntheses
All reactions with organometallic reagents or sub-
strates were carried out under argon using standard Sch-
lenk techniques. Solvents were dried and distilled under
nitrogen prior to use. The prepared derivatives were
characterised by elemental analysis and spectroscopic
methods. The IR spectra were recorded with a FT-IR
spectrometer Perkin–Elmer Spectrum 2000. The NMR
spectra were recorded using Varian Gemini XL 300
(1H, 300.1; 13C, 75.5 MHz), Varian MercuryPlus VX
400 (1H, 399.9; 13C, 100.6 MHz), Varian Inova 600
(1H, 599.7, 13C, 150.8 MHz) instruments. The spectra
were referenced internally to residual solvent resonances
and were recorded at 298 K for characterization pur-
poses. EI-MS spectra were taken using a VG 7070E
mass spectrometer. ESI-MS analysis were performed
by direct injection of methanol solutions of the metal
3.1.1. Preparation of [Na][C5H4C(O)CH3]
A mixture of NaCp (1.26 g, 14.3 mmol) and 3-ace-
tyl-oxazolidin-2-one (0.93 g, 7.2 mmol) in THF (50

822
L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 818–824
Table 2
Crystal data and details of structure refinement for complexes 3 and 4
uum at 60 ꢁC for 2 h. The resulting solid was washed
with Et2O to give 8.61 g (91%) of 1 as a beige solid.
1H NMR (599.7 MHz, [D5]Pyr): d = 7.96 (AA0BB0,
3
4
3
3JH,H = 7.8 Hz, 2H; Ts) 7.36 (AA0BB0, JH,H = 2.7 Hz,
Empirical formula
Formula weight
Temperature (K)
C22H24NO4SRh
501.39
193
C23H26NO4SRh
515.42
193
3
2H; Cp), 7.00 (AA0BB0, JH,H = 7.8 Hz, 2H; Ts), 6.60
3
3
(AA0BB0, JH,H = 2.7 Hz, 2H; Cp), 4.61 (t, JH,H = 5.9
˚
Wavelength (A)
0.71069
Monoclinic
P21/n, no. 14
0.71069
Monoclinic
P21, no. 4
3
Hz, 2H; CO2CH2), 3.52 (t, JH,H = 5.9 Hz, 2H;
Crystallographic system
Space group
Unit cell dimensions
CH2N), 2.14 (s, 3H; Me); 13C{1H} NMR (150.8 MHz,
[D5]Pyr): d = 169.3 (C@O), 150.2 (ipso-C; Ts), 139.6
(ipso-C, Ts), 129.1 (CH, Ts), 127.4 (CH, Ts), 112.8
(CH, Cp), 111.3 (CH, Cp), 109.6 (ipso-C, Cp), 64.5
˚
a (A)
19.7525(6)
5.7898(2)
20.2419(6)
117.296(1)
2057.2(1)
4
9.2874(6)
6.0903(4)
37.184(2)
96.948(1)
2087.8(2)
4
˚
b (A)
˚
c (A)
(CO2C2), 46.6 (CH2N), 21.1 (CH3). IR (THF, cmꢀ1
)
b (ꢁ)
Volume (A )
3
˚
m(C@O) 1635 (bs). Anal. Calcd. for C15H14Na2NO4S:
C, 51.4; H, 4.03; Found: C, 51.7; H, 4.06%. The GC–
MS (m/z, %) analysis of the volatiles showed the pres-
ence of (C5H6)2: 132 ([M]+, 17), 66 ([C5H6]+, 100).
Z
Crystal size (mm)
Maximum h for data
collection (ꢁ)
0.18 · 0.21 · 0.34
30
0.15 · 0.24 · 0.40
30
Number of reflections
21,735
4913
26,940
6628
3.1.3. Preparation of [Rh{g5-
C5H4CO2(CH2)2N(H)Ts}(NBD)] (3)
collected
Number of observed
induced reflections
Number of parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
(R1 and wR2)
To a solution of 1 (0.84 g, 2.39 mmol) in THF (25
mL), solid [Rh(NBD)Cl]2 (0.47 g, 1.02 mmol) was
added. After stirring 3 h at room temperature, all the
starting rhodium reagent has reacted as judged by
TLC. The solvent was removed under vacuum and
CH2Cl2 was added. The suspension was stirred for fur-
ther 3 h and then first filtered on a celite pad and subse-
quently chromatographed on silica gel employing
straight Et2O as the eluting solvent. A yellow fraction
was collected and identified as the title compound 3
230
1.00
238
1.17
0.033 and 0.084
0.056 and 0.119
R indices (all data)
(R1 and wR2)
Largest difference peak
0.040 and 0.089
0.062 and 0.121
0.81 and ꢀ0.63
0.84 and ꢀ0.93
ꢀ3
˚
and hole (e A
)
1
mL) was stirred at r.t. for 24 h to give a brownish solu-
tion along with a white precipitate. The reaction mix-
ture was filtered. After evaporation of the solvent
under reduced pressure 0.90 g (96%) of a light brown
solid were obtained and identified as [Na][C5H4-
(0.84 g, 82%). H NMR (399.9 MHz, CDCl3): d = 7.78
3
3
(AA0BB0, JH,H = 8.0 Hz, 2H; Ts), 7.25 (d, JH,H = 8.0
3
Hz, 2H; Ts) 5.40 (AA0BB0, JH,H = 2.1 Hz, 2H; Cp),
3
5.31 (AA0BB0X, JH,H = 2.1 Hz, JH,Rh = 0.9 Hz, 2H;
3
Cp), 5.14 (t, JH,H = 6.0 Hz, 1H; NHTs), 4.20 (t,
1
C(O)CH3] by comparison of the H NMR spectra in
3JH,H = 5.4 Hz, 2H; CO2CH2), 3.32 (m, 8H; H1,2,3,4,5,6
,
NBD, CH2N overlapping peaks), 2.37 (s, 3H; CH3),
D2O with the literature data [5]. We here report the
not previously described NMR spectra of [Na][C5H4-
C(O)CH3] in [D5]Pyr. 1H NMR (300.1 MHz,
[D5]Pyr): d = 7.39 (m, 1H; Cp), 7.15 (m, 1H; Cp),
6.66 (m, 2H; Cp), 2.49 (s, 3H; Me); 13C–{g1H} NMR
(75.5, [D5]Pyr): d = 187.6 (C@O), 117.1, 115.8, 113.6,
111.3 (CH; Cp), 26.3 (CH3).
The NMR analysis of the white solid revealed to be
the oxazolidin-2-one sodium salt while the GC–MS
analysis of the volatiles showed the presence of
(C5H6)2.
0.99 (t, JH,H = 1.4 Hz, 2H; H7, NBD); 13C{1H} NMR
3
(100.6 MHz, CDCl3): d = 165.9 (C@O), 143.4 (ipso-C,
Ts), 136.9 (ipso-C, Ts), 129.7 (CH, Ts), 126.9 (CH,
Ts), 90.9 (d, JC,Rh = 4.6 Hz; ipso-C, Cp), 88.5 (d,
JC,Rh = 4.0 Hz; CH, Cp), 85.9 (d, JC,Rh = 4.0 Hz; Cp),
62.1 (CO2CH2), 57.5 (d, JC,Rh = 6.5 Hz; C7, NBD),
46.7 (d, JC,Rh = 2.4 Hz; C1,4, NBD), 42.6 (CH2N), 32.7
(d, JC,Rh = 10.5 Hz; C2,3,5,6, NBD), 21.4 (CH3). 1H
NMR (399.9 MHz, [D8]Toluene): d = 7.67 (AA0BB0,
3
3JH,H = 8.2 Hz, 2H; Ts), 6.78 (d, JH,H = 8.2 Hz, 2H;
3
Ts) 5.45 (AA0BB0, JH,H = 2.2 Hz, 2H; Cp), 5.04
3
3.1.2. Preparation of [Na]2[C5H4CO2(CH2)2NTs] (1)
To a solution of NaCp (4.74 g, 53.9 mmol) in THF
(100 mL), solid 3-tosyl-oxazolidin-2-one was added
(6.51 g, 27.0 mmol). The mixture was stirred for 24 h
at room temperature and during this time it turned from
an heterogeneous system (the oxazolidin-2-one is spar-
ingly soluble in THF) to a slightly turbid solution fil-
tered on a celite pad. After filtration, the volatiles were
removed under vacuum and the residue kept under vac-
(AA0BB0X, JH,H = 2.2 Hz, JH,Rh = 0.9 Hz, 2H; Cp),
3
4.55 (t, JH,H = 6.0 Hz, 1H; NHTs), 3.91 (t,
3JH,H = 5.4 Hz, 2H; CO2CH2), 3.27 (m, 4H; H2,3,5,6
NBD), 3.18 (m, 2H; H1,4, NBD), 2.92 (m, 2H; CH2N),
,
3
1.94 (s, 3H; CH3), 0.88 (t, JH,H = 1.6 Hz, 2H; H7,
NBD). IR (THF, cmꢀ1): m = 1712 (s) (C@O). ESI-MS
[M]+ + Na = 524 m/z. Anal. Calcd. for C22H24NO4RhS:
C, 52.8; H, 4.63; Found: C, 52.7; H, 4.64%. m.p. = 114
to 116 ꢁC. Rf(Et2O, SiO2) = 0.39.

L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 818–824
823
In a parallel experiment, the in situ generated
[Na][Rh{C5H4CO2(CH2)2NTs}(NBD)] (2) was analysed
by NMR spectroscopy as follows: after 3 h a portion of
the crude mixture was transferred with a cannula to a
NMR tube. The solvent was removed under vacuum
and after addition of [D5]Pyr the tube was flame sealed
[M]+ + Na@538 m/z. Anal. Calcd. for C23H26NO4RhS:
C, 53.6; H, 5.05; Found: C, 53.6; H, 5.04%. m.p. = 104
to 106 ꢁC. Rf(Et2O, SiO2) = 0.50.
3.2. X-ray crystallography
1
under argon. NMR data for 2: H NMR (1H, 399.9
Yellow crystals of 3 and 4 suitable for the X-ray dif-
fraction studies were precipitated from a double layer
CH2Cl2/Etp at ꢀ20 ꢁC. Crystal data and details of struc-
ture refinement are reported in Table 2.
3
MHz, [D5]Pyr): d = 8.09 (AA0BB0, JH,H = 8.4 Hz, 2H;
3
Ts), 7.18 (AA0BB0, JH,H = 8.4 Hz, 2H; Ts), 5.70 (m,
3
2H; Cp), 5.35 (m, 2H; Cp), 4.64 (t, JH,H = 5.9 Hz,
3
2H; CO2CH2), 3.49 (t, JH,H = 5.9 Hz, 2H; CH2N),
Diffraction intensities were collected on a Bruker
AXS SMART 2000 CCD diffractometer. The data were
collected using 0.3ꢁ wide x scans, crystal-to-detector
distance of 5.0 cm, and corrected for absorption using
the SADABS routine [8]. Data collections nominally cov-
ered a full sphere of reciprocal space for both com-
plexes with 10 s exposure time per frame. Both
structures were solved by direct methods and refined
on F2 by full-matrix least-squares calculations using
the SHELXTL/PC package [9]. The structure of 3 was
found affected by disorder at the CH2NHTs moiety,
which could be refined using the Ts fragment taken
from molecule 4 as a starting model for the two slightly
displaced images. An occupation factor of ca. 0.5 was
refined. Two independent isomeric molecules were
found packed in an orderly way in the crystals of 4.
Thermal vibrations were treated anisotropically in 3,
except for the disordered moiety, while could be treated
only isotropically in 4, except for Rh and S atoms, due
to the high correlation between parameters and conse-
quent instability of the least squares calculations. The
absolute configuration was assigned to the molecules
in the crystal of 4, as reported in Fig. 2, by using the
Flack parameter (ꢀ0.0005 for the correct absolute
structure) [10]. H atoms were experimentally located
3.36 (m, 4H; H2,3,5,6, NBD), 3.18 (m, 2H; H1,4, NBD),
3
2.19 (s, 3H; Me), 0.85 (t, JH,H = 1.7 Hz, 2H; H7,
NBD); 13C{1H} NMR (100.6 MHz, [D5]Pyr):
d = 166.2 (C@O), 141.1 (ipso-C, Ts), 129.4, 127.4 (Ts),
88.9 (d, JC,Rh = 5.0 Hz; ipso-C, Cp), 88.7 (d, JC,Rh = 4.5
Hz; CH, Cp), 86.7 (d, JC,Rh = 4.2 Hz; CH, Cp), 65.4
(CO2C2), 57.5 (d, JC,Rh = 6.9 Hz; C7, NBD), 47.0 (d,
JC,Rh = 2.9 Hz; C1,4, NBD), 44.9 (CH2NHTs), 32.6 (d,
JC,Rh = 10.5 Hz; C2,3,5,6, NBD), 21.1 (CH3).
3.1.4. Preparation of [Rh{g5-
C5H4CO2(CH2)2N(Me)Ts}(NBD)] (4)
To a solution of 1 (0.37 g, 1.1 mmol) in THF (25 mL),
solid [Rh(NBD)Cl]2 (0.20 g, 0.43 mmol) was added.
After stirring 3 h at room temperature 0.2 mL of freshly
distilled MeI was slowly added with a syringe. After 4 h,
the solvent was removed under vacuum and CH2Cl2 was
added. The suspension was first filtered on a celite pad
and then chromatographed on silica gel using Et2O/
Etp (1:1) as the eluting solvent. A yellow fraction was
collected and identified as the title compound (0.34 g,
77%). 1H NMR (399.9 MHz, CDCl3): d = 7.68
3
(AA0BB0, JH,H = 8.1 Hz, 2H; Ts), 7.30 (AA0BB0,
3JH,H = 8.1 Hz, 2H; Ts), 5.46 (m, 2H; Cp), 5.34 (m,
3
2H; Cp), 4.35 (t, JH,H = 5.6 Hz, 2H; CO2CH2), 3.35
˚
but geometrically positioned [C–H 0.93 and 0.97 A
3
(t, JH,H = 5.6 Hz, 2H; CH2N), 3.32 (m, 4H; H2,3,5,6
,
NBD), 3.30 (m, 2H; H1,4, NBD), 2.88 (s, 3H; NCH3),
for aromatic and aliphatic distances] and refined ‘‘rid-
ing’’ on their corresponding carbon atoms. The N–H
distance in 3 was constrained to an average value of
3
2.41 (s, 3H; CH3), 0.99 (t, JH,H = 1.4 Hz, 2H; H7,
NBD); 13C{1H} NMR (100.6 MHz, CDCl3): d = 165.7
(C@O), 143.4 (ipso-C, Ts), 134.7 (ipso-C, Ts), 129.7
(CH, Ts), 127.3 (CH, Ts), 91.5 (d, JC,Rh = 4.0 Hz;
ipso-C, Cp), 88.4 (d, JC,Rh = 4.0 Hz; CH, Cp), 86.0 (d,
JC,Rh = 4.0 Hz; Cp), 61.9 (CO2C2), 57.5 (d, JC,Rh = 6.5
Hz; C7, NBD), 49.1 (CH2N), 46.7 (d, JC,Rh = 2.4 Hz;
0.89(1) A in the two images. Refinement converged at
˚
a final R = 0.033 for 3 and R = 0.056 for 4. Molecular
graphics were prepared using ORTEP3 for Win-
dowsNT [11].
CCDC-242972 (3) and CCDC-242973 (4) contain the
supplementary crystallographic data for this paper.
These data can be obtained free of charge on application
to CCDC, 12 Union Road, Cambridge CB21EZ, UK
[Fax: (internat.) +44-1223-336-033; E-mail: deposit@
ccdc.cam.ac.uk].
C
C
1,4, NBD), 36.0 (NCH3), 32.6 (d, JC,Rh = 10.5 Hz;
2,3,5,6, NBD), 21.5 (CH3). 1H NMR (399.9 MHz,
3
[D8]Toluene): d = 7.55 (AA0BB0, JH,H = 8.2 Hz, 2H;
3
Ts), 6.79 (AA0BB0, JH,H = 8.2 Hz, 2H; Ts), 5.53
3
(AA0BB0, JH,H = 2.2 Hz, 2H; Cp), 5.05 (AA0BB0X,
3JH,H = 2.2 Hz, JH,Rh = 0.8 Hz, 2H; Cp), 4.15 (t,
3JH,H = 5.6 Hz, 2H; CO2CH2), 3.29 (m, 4H; H2,3,5,6
,
NBD), 3.18 (m, 2H; H1,4, NBD), 3.05 (t, JH,H = 5.6
Hz, 2H; CH2N), 2.56 (s, 3H; NCH3), 1.94 (s, 3H;
Acknowledgements
3
The authors thank the University of Bologna and the
`
Ministero della Industria, Universita e Ricerca (MIUR),
Programmi di Ricerca Scientifica di Notevole Interesse
3
CH3), 0.89 (t, JH,H = 1.6 Hz, 2H; H7, NBD). IR
(THF, cmꢀ1): m = 1712 (s) (C@O). ESI-MS

824
L. Busetto et al. / Journal of Organometallic Chemistry 690 (2005) 818–824
(b) L. Busetto, M.C. Cassani, V.G. Albano, P. Sabatino,
Organometallics 21 (2002) 1849–1855;
Nazionale, Cofinanziamento MIUR 2003-04, for finan-
cial support.
(c) L. Busetto, M.C. Cassani, R. Mazzoni, V.G. Albano, P.
Sabatino, P. Frediani, E. Rivalta, Organometallics 21 (2002) 4993–
4999;
(d) L. Busetto, M.C. Cassani, R. Mazzoni, P. Frediani, E. Rivalta,
J. Mol. Catal. A: Chemical 206 (2003) 153–161;
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