Regioselective cyclomanganation of Schiff bases. An unexpected effect of chloro substituents

Article abstract of DOI:10.1016/j.jorganchem.2004.07.010

The synthesis of new metallacycles of benzyl-benzylidene-amines by using [MnMe(CO)₅] as metallating agent is reported. The results described suggest that cyclomanganation takes place by the formation of a four-centered transition state, involving the C-H and Mn-C_acetyl bonds, in the acetyl coordination complex formed in the first step of the reaction. In this paper we describe the synthesis of new metallacycles by the cyclomanganation reaction of benzyl-benzylidene-amines by using [MnMe(CO)₅] as metallating agent. These ligands can undergo metallation on different aromatic carbon atoms but no important differences have been found in the regioselectivity of the process, that can be related to the electronic effect of the substituents, and in all the cases studied the endo-cyclomanganated complexes of para-substituted imines have been obtained. The corresponding exo-metallacycles were obtained by reaction of [MnMe(CO)₅] on the imine 2,6-Cl₂C₆H₃CH=NCH₂Ph and 2,4,6-Me₃C₆H₂CH=NCH₂Ph, derived from 2,6-dichlorobenzaldehyde and 2,4,6-trimethylbenzaldehyde, respectively. The results described suggest that the mechanism of the cyclomanganation is similar to that of cyclopalladation and it can be proposed that cyclomanganation takes place by the formation of a four-centered transition state, involving the C-H and Mn-C_acetyl bonds, in the acetyl coordination complex formed in the first step of the reaction.

Full text of DOI:10.1016/j.jorganchem.2004.07.010

Journal of Organometallic Chemistry 689 (2004) 4889–4896
www.elsevier.com/locate/jorganchem
Regioselective cyclomanganation of Schiff bases. An unexpected
effect of chloro substituents
a
a
a,
b
Joan Albert , J. Magali Cadena , Jaume Granell *, Xavier Solans ,
b
`
Merce Font-Bardia
a
´ `
Departament de Quımica Inorganica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
´
Departament de Cristallografia, Mineralogia i Diposits Minerals, Universitat de Barcelona, Martı i Franques s/n, 08028 Barcelona, Spain
b
`
`
Received 12 May 2004; accepted 3 July 2004
Available online 11 November 2004
Abstract
In this paper we describe the synthesis of new metallacycles by the cyclomanganation reaction of benzyl-benzylidene-amines by
using [MnMe(CO)5] as metallating agent. These ligands can undergo metallation on different aromatic carbon atoms but no impor-
tant differences have been found in the regioselectivity of the process, that can be related to the electronic effect of the substituents,
and in all the cases studied the endo-cyclomanganated complexes of para-substituted imines have been obtained. The corresponding
exo-metallacycles were obtained by reaction of [MnMe(CO)5] on the imine 2,6-Cl2C6H3CH@NCH2Ph and 2,4,6-Me3C6H2-
CH@NCH2Ph, derived from 2,6-dichlorobenzaldehyde and 2,4,6-trimethylbenzaldehyde, respectively.
The results described suggest that the mechanism of the cyclomanganation is similar to that of cyclopalladation and it can be
proposed that cyclomanganation takes place by the formation of a four-centered transition state, involving the C–H and Mn–Cacetyl
bonds, in the acetyl coordination complex formed in the first step of the reaction.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Imines; Manganese; Metallacycles; Metallation
1. Introduction
on the cyclomanganation of N-donor ligands. Bruce et al.
[3], in early reports, described the cyclomanganation of
azobenzene, benzylideneaniline and benzylidenemethyl-
amine and some studies on the cyclomanganation of dif-
ferent amines, imines, hydrazones and azines have been
recently reported.
Some of these studies deal with the regioselectivity of
the manganation reaction. Bruce et al. [3b] reported that
cyclomanganation of azobenzenes takes place in the
most electron-rich aromatic ring and they concluded
that cyclomanganation reactions with [MnR(CO)5] oc-
cur by a nucleophilic attack of the metal complex. In
contrast, a subsequent paper by Sales and coworkers
described the impossibility of synthesising any cyclo-
manganated derivative with azines, containing nitro
substituents, and they proposed that the cyclomangana-
tion process takes place by an electrophilic attack of the
Cyclometallation reactions were one of the first
known examples of C–H bond activation and cyclome-
tallated complexes of a wide variety of ligands, contain-
ing N, P, As, O or S, as the heteroatom has been
described [1]. The cyclopalladation of N-donor ligands
has been extensively studied and it has acquired great in-
terest because of the application of the metallacycles in
many areas including organic synthesis, homogenous ca-
talysis, the design of new metallomesogenes and antitu-
moral drugs [2]. In contrast less work has been reported
*
Corresponding author. Tel.: +34-93-402-1274; fax: +34-93-490-
7725.
E-mail addresses: jaume.granell@qi.ub.es (J. Granell), jgranell@
kripto.qui.ub.es (J. Granell).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.07.010

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J. Albert et al. / Journal of Organometallic Chemistry 689 (2004) 4889–4896
manganese compound on the ligand [3f]. Pfeffer et al.
[3g] reported the cyclomanganation of tertiary amines
and suggested that the manganese complex can react
via a multicentered pathway. Finally, a more recent pa-
per by Rourke et al. [3e,4] proposed that the first steps of
the cyclomanganation reaction are the migration of the
methyl group of the [MnMe(CO)5] complex onto a car-
bonyl, generating a vacant coordination site, followed
by the coordination of the ligand. These authors also
propose a final nucleophilic attack by the manganese
on the aromatic ring.
In this paper we describe the cyclomanganation
reaction of benzyl-benzylidene-amines by using [MnMe
(CO)5] as metallating agent. These imines are particu-
larly suitable ligands for the study of the regioselectivity
of cyclometallation reactions, since they can undergo
metallation on different aromatic carbon atoms.
erties of imine-platinum(II) compounds support the
electronic delocalization within the metallated system
[9]. Some kinetics studies on the cyclopalladation of imi-
nes have also been reported [10]. These studies suggest
that the cyclopalladation of imines takes place via a first
step, the formation of an imine-palladium coordination
complex, followed by a second rate-determining step.
The formation of a highly ordered transition state in
which there is a four centered interaction between the
carbon and hydrogen atoms of the C–H bond to be ac-
tivated, the oxygen atom of the acetato leaving group
and the metal explains the kinetic data. The planarity
of the PhC@N fragment on the imines facilitates the for-
mation of such intermediate with the ortho C–H bond of
the methinic phenyl group.
It has been shown that exo-metallacycles can be ob-
tained by cyclopalladation of imines if the ortho posi-
tions of the methinic phenyl ring (which leads to the
formation of endo-metallacycles) are blocked by substit-
uents such as chlorine atoms [11]. Following and ex-
panding this strategy to prepare exo-cyclic imine
cyclomanganated derivatives, the action of [MnMe-
(CO)5] on the imines 1f and 1g, derived from 2,6-dichlo-
robenzaldehyde and 2,4,6-trimethylbenzaldehyde, was
studied. When the reaction was performed with imine
1f two cyclomanganated compounds, 2e and 3f were ob-
tained in 1/1 ratio. NMR data showed that 3f is the exo-
derivative containing the imine in the Z form, obtained
by activation of a Caromatic–H bond. NMR data also
showed that the endo-metallacycle 2e (previously iso-
lated from imine 1e by activation of a Caromatic–H bond)
was also obtained, in this case by activation of the ortho
C–Cl bond of the imine 1f. The significant amount of
compound 3f formed is not compatible with a nucleo-
philic attack of Mn complex to C–X bonds, because it
is well known that Caromatic–Cl bonds are more labile
in front to nucleophilic attack than Caromatic–H bonds
[12]. When the cyclomanganation reaction was per-
formed with imine 1g the exo-metallacycle 3g was ob-
tained, but the formation of the endo-complex 2g, by
activation of a Caliphatic–H bond, was also observed.
Compound 3g was fully characterised but, in contrast
2g is surprisingly unstable and good analytical data were
not obtained for this compound.
2. Results and discussion
Scheme 1 shows the cyclomanganated compounds
prepared in this work by reaction between benzyl-benzy-
lidene-amines and [MeMn(CO)5] in refluxing octane un-
der an inert atmosphere. These imines can undergo
metallation on different carbon atoms, giving organome-
tallic complexes of different structures: endo-metallacy-
cles, if the C@N bond is included in the metallacycle,
or exo-derivatives (see Fig. 1). In addition, imines can
exist in E or Z isomers, but in general, N-aldimines
adopt the more stable E form [5]. Endo- or exo-metalla-
cycles can be obtained from imines in E-form but exo-
derivatives can only be formed from the Z-isomer.
Overall NMR data showed that with imines 1a–1e
only the endo-derivative was formed. This finding shows
that, in the manganation reaction of imines, the so-
called endo effect is more important than the electronic
effect of substituents. In the case of 1d, which presents
two non-equivalent potential metallation sites (C2 and
C6), only one isomer was obtained and proton NMR
spectrum clearly shows that the metallation occurs in
the less hindered C–H bond.
The endo effect has been reported for the cyclopalla-
dation of imines [6] and for the oxidative addition of
C–X bonds ortho-halosubstituted imines to Ni(0),
Pd(0), Pt(II) and W(0) complexes [7]. It should be noted
that in some cases the oxidative addition of C–F bonds
(126 kcal/mol) or C–Cl bonds (96 kcal/mol) to form
endo-metallacycles takes place in preference to the oxi-
dative addition of C–Br bonds (81 kcal/mol) or C–I
bonds (65 kcal/mol) to form exo-derivatives.
All the new organometallic compounds obtained
were characterised by elemental analysis, IR spectra,
1
and H NMR spectra. In some cases, 2D NMR experi-
ments and positive FAB-mass spectra were carried out
to complete the characterisation.
The IR spectra of the carbonyl region showed the ex-
pected four-band pattern for the cyclomanganated de-
rivatives and the stretching frequencies can be related
to the electronic effect of the substituents. For example
the stretching frequencies of the carbonyls in the MeO
compound 2b are 8–10 cmꢀ1 lower than those of the
chloro substituted derivatives 2a, 2d and 2e. This can
The aromaticity of the five-membered metallacycle,
involving the two conjugated bonds C@C, C@N and
the filled d orbital of the metal of appropriate symmetry
has been proposed to explain the greater stability of
endo-cyclic compounds [8] and the electrochemical prop-

J. Albert et al. / Journal of Organometallic Chemistry 689 (2004) 4889–4896
4891
R1
R1
3
4
5
6
2
H
H
C
N
i
C
1
Mn(CO)4
N
2a, R1 = 5-Cl
2b, R1 = 5-MeO
2c, R1 = 5-NO2
2d, R1 = 4-Cl
2e, R1 = 3-Cl
1a, R1 = 4-Cl
1b, R1 = 4.MeO
1c, R1 = 4-NO2
1d, R1 = 3-Cl
1e, R1 = 2-Cl
Cl
Cl
Cl
H
H
H
C
C
i
C
Cl
+
Cl
N
Mn(CO)4
N
N
(OC)4Mn
3f
2e
1f
Me
Me
Me
Me
Me
Me
H
H
H
C
C
i
C
CH2
+
Me
Me
N
N
N
Mn
(CO)4
(OC)4Mn
3g
2g
1g
Scheme 1. i: [MnMe(CO)5], refluxing octane.
H
H
C
N
C
endo-metallacycle
N
M
M
M
exo-metallacycle
exo-metallacycle
E-form
Z-form
Fig. 1.
be explained in terms of the higher electron density pre-
sent in the case of the more electron donating MeO
group, that increases the back-bonding to carbonyls.
The FAB mass spectra of the manganated complexes
showed the signals corresponding to the molecular peak
and also exhibited the signals corresponding to ions aris-
ing from the usual stepwise loss of carbonyl groups.
The proton NMR spectra provided a conclusive evi-
dence on the metallation position, and also on the E/Z
configuration of the imine. The methinic proton signal
in compounds 2a–2d appeared at a d value close to that
of the methinic proton of the free imines, in agreement
with an E configuration for this ligand. In contrast, this
signal appeared shifted to low field in relation to free

4892
J. Albert et al. / Journal of Organometallic Chemistry 689 (2004) 4889–4896
imine in 3f and 3g. This downfield shift can be explained
by the paramagnetic anisotropy of the metal [13] and
suggests that the imine, in these compounds, adopt a
Z configuration in which this proton is close to the metal
atom, which minimises steric repulsions [11]. In addi-
tion, the coupling between CH2N and HC@N protons
confirms the Z-form of the imine in these compounds.
For all the compounds containing a chlorine substituent
in an ortho position on the aromatic ring (1e, 1f, 2e and
3f) the HC@N proton resonance appeared at lower
fields than for the non-substituted derivatives, indicating
an intramolecular interaction between the atoms, as has
been found for related palladium and platinum metalla-
cycles [14].
Suitable crystals for the determination of the crystal
structure of compound 3g were grown in hexane solu-
tion, at room temperature, and their crystal structure
has been determined (Fig. 2). Selected bond lengths
and angles are listed in Table 1. The crystal structure
is composed of discrete molecules separated by van
der Waals distances. The manganese is coordinated in
a distorted octahedral disposition and the bond lengths
and angles are similar to others previously reported for
cyclomanganated complexes [3g,3e]. The metallacycle
presents an exo-configuration and the imine is in the
Z-form.
nated complexes of para-substituted imines have been
obtained with similar yields (30–45%), in good agree-
ment with the results previously described for the cy-
clopalladation of these ligands. These results show
that the planarity of the PhC@N fragment on the imi-
nes plays a key role on the regioselectivity of the proc-
ess. This is the first time that it has been shown that
the endo effect is important in cyclomanganation
reactions.
It should be noted that imine 1e, which contains a
chloro substituent in the ortho position of the methinic
phenyl group, is the only ligand that affords the cyclo-
manganated complex in high yield (70%). This result
cannot be explained by the standard effect of the sustit-
uents. It should be noted that the proton NMR spec-
trum of this imine shows the existence of an
interaction between the ortho C–Cl bond and the methi-
nic proton (see above). This CHꢁ ꢁ ꢁCl interaction rein-
forces the planarity of the ArCH@N fragment and
brings the C–H bond to be activated close to the metal
in the intermediate coordination complex, thus making
easy the metallation process. This effect have been re-
cently proposed to explain the results obtained in the
oxidative addition of C–Cl bonds of imines to [Pt(dba)2]
[15].
All these results suggest that the mechanism of the cy-
clomanganation reactions can be similar to that of cy-
clopalladation and, in consequence, cyclomanganation
takes place by the formation of a four-centered transi-
tion state, involving the C–H and Mn–Cacetyl bonds, in
In summary no important differences have been
found in the manganation reaction of imines that
can be related to the electronic effect of the substitu-
ents and in all the cases studied the endo-cyclomanga-
Fig. 2. Molecular structure of compound 3g.

J. Albert et al. / Journal of Organometallic Chemistry 689 (2004) 4889–4896
4893
Table 1
Crystal data and structure refinement for 3g
eter using octane solutions. Mass spectra were
recorded on a Fisons VG-Quattro spectrometer. The
samples were introduced in a matrix of 2-nitrobenzyl-
alcohol for FAB analysis and then bombarded with
caesium atoms.
Empirical formula
Formula weight
Temperature (K)
C21H18MnNO4
403.30
293(2)
0.71073
Monoclinic, P21/c
˚
Wavelength (A)
Crystal system, space group
Unit cell dimensions
3.2. Materials and synthesis
˚
a = 7.0580(10) A, a = 90ꢁ
b = 12.4250(10) A, b = 94.480(10)ꢁ
˚
All the reactions were carried out using Schlenk tech-
niques under nitrogen atmosphere. All solvents were
dried and degassed by standard methods. All chemicals
were of commercial grade and used as received.
[MnMe(CO)5] was prepared according to the procedure
described elsewhere [16].
˚
c = 22.0920(10) A, c = 90ꢁ
1931.5(3)
3
˚
Volume (A )
Z, calculated density (Mg/m3)
4, 1.387
0.709
Absorption coefficient (mmꢀ1
F (000)
Crystal size (mm)
)
832
0.1 · 0.1 · 0.2
3.22–31.78ꢁ
Theta range for data collection
Limiting indices
ꢀ9 6 h 6 0, ꢀ15 6 k 6 15,
3.3. Synthesis of imines 1a–1f
ꢀ32 6 l 6 32
Reflections collected/unique
Absorption correction
Refinement method
40734/3665 [R(int) = 0.0349]
None
A mixture of benzylamine (243 mg, 2.26 mmol) and
the corresponding aldehyde (2.26 mmol) was refluxed
in ethanol for 3 h. The resulting solution was concen-
trated in vacuo and the oil obtained was characterised
Full-matrix least-squares on F2
3665/0/316
1.108
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
R1 = 0.0502, wR2 = 0.1314
R1 = 0.0625, wR2 = 0.1387
0.295 and ꢀ0.298
1
by IR and H NMR spectra and was used without fur-
Largest differential peak
ꢀ3
ther purification.
˚
and hole (eA
1H NMR (200 MHz, CDCl3) data for 1a: d = 4.80 (s,
2H, CH2Ph); 7.29–7.39 (m, 5H, aromatic); 7.69 (d, 2H,
JHH = 8.4 Hz, aromatic); 8.32 (s, 1H, CH@N).
1H NMR (200 MHz, CDCl3) data for 1b: d = 3.85 (s,
3H, CH3O); 4.79 (s, 2H, CH2Ph); 6.93 (d, 2H,
JHH = 8.2 Hz, aromatic); 7.31–7.35 (m, 5H, aromatic);
7.74 (d, 2H, JHH = 8.2 Hz, aromatic); 8.33 (s, 1H,
CH@N).
)
H
C
N
H
1H NMR (200 MHz, CDCl3) data for 1c: d = 4.89 (s,
2H, CH2Ph); 7.32–7.38 (m, 5H, aromatic); 7.94 (d, 2H,
JHH = 8.6 Hz, aromatic); 8.27 (d, 2H, JHH = 8.4 Hz,
aromatic); 8.46 (s, 1H, CH@N).
COMe
Mn
1H NMR (200 MHz, CDCl3) data for 1d: d = 4.82 (s,
2H, CH2Ph); 7.28–7.38 (m, 6H, aromatic); 7.61 (d, 1H,
JHH = 7.6 Hz, aromatic); 7.80 (s, 1H, aromatic); 8.32
(s, 1H, CH@N).
Fig. 3.
1H NMR (200 MHz, CDCl3) data for 1e: d = 4.86 (s,
2H, CH2Ph); 7.27–7.36 (m, 8H, aromatic); 8.09 (d, 2H,
JHH = 8.0 Hz, aromatic); 8.84 (s, 1H, CH@N).
1H NMR (200 MHz, CDCl3) data for 1f: d = 4.93 (s,
2H, CH2Ph); 7.20–7.38 (m, 8H, aromatic); 8.56 (s, 1H,
CH@N).
the acetyl coordination complex formed in the first step
of the reaction (see Fig. 3).
3. Experimental
1H NMR (200 MHz, CDCl3) data for 1g: d = 2.26 (s,
3H, Me); 2.40 (s, 6H, Me); 4.82 (s, 2H, CH2Ph); 6.85 (s,
2H, aromatic); 7.27–7.36 (m, 5H, aromatic); 8.70 (s, 1H,
CH@N).
3.1. General
1H NMR spectra at 200 MHz were recorded in a
Varian Gemini 200 spectrometer. Chemical shifts (in
ppm) were measured relative to SiMe4. Microanalyses
3.4. Synthesis of 2a–2g
`
were performed at the Institut de Qu´ımica Bio-Orga-
nica de Barcelona and the Servei de Recursos Cientifics
`
I Tecnics (Universitat Rovira i Virgili). Infrared spec-
tra were recorded with a Nicolet 520 FT-IR spectrom-
Compound [(CO)4Mn(5-ClC6H3CH@NCH2Ph)] (2a).
Under an inert atmosphere, [MeMn(CO)5] (44.8 mg,
0.21 mmol) and ligand 1a (48.2 mg, 0.21 mmol) were
dissolved in octane (15 ml) and refluxed for 2 h. The

4894
J. Albert et al. / Journal of Organometallic Chemistry 689 (2004) 4889–4896
solution obtained was eluted by column chromato-
graphy over SiO2, with hexane as eluent to obtain
compound 2a in 42% yield (36 mg).
Characterisation data for 2d. Anal. (%) Calcd. for
C18H11ClNO4Mn: C: 54.64, H: 2.80, N: 3.54. Found:
1
C, 56.6; H, 3.0; N, 3.3. H NMR (200 MHz, CDCl3):
Characterisation data for 2a. Anal. (%) Calcd. for
C18H11ClNO4Mn: C: 54.64, H: 2.80, N: 3.54. Found:
d = 4.91 (s, 2H, CH2Ph); 7.22–7.26 (m, 3H, aromatic);
7.37–7.40 (m, 3H, aromatic); 7.55 (d, 1H, JHH = 2.0
Hz, H3); 7.85 (d, 1H, JHH = 7.8 Hz, H6); 8.34 (s, 1H,
CH@N). IR (cmꢀ1): m(CO) 1946 m, 1985 m, 1997 s,
2078 w. FAB-MS, m/z: 395 [M], 368 [M–CO], 339 [M–
2CO], 311 [M–3CO], 283 [M–4CO].
1
C, 54.4; H, 2.7; N, 3.5. H NMR (200 MHz, CDCl3):
d = 4.91 (s, 2H, CH2Ph); 7.12 (dd, 1H, JHH = 8.2 Hz,
JHH = 1.8 Hz, H4); 7.23–7.27 (m H, aromatic); 7.36–
7.41 (m, H, aromatic); 7.49 (d, 1H, JHH = 8.2 Hz,
H3); 7.90 (d, 1H, JHH = 1.8 Hz, H6); 8.35 (s, 1H,
CH@N). IR (cmꢀ1): m(CO) 1949 m, 1986 m, 1999 s,
2079 w. FAB-MS, m/z: 395 [M], 368 [M–CO], 339 [M–
2CO], 311 [M–3CO], 283 [M–4CO].
Compound
[(CO)4Mn(3-ClC6H3CH@NCH2Ph)]
(2e). Under an inert atmosphere, [MeMn(CO)5] (27.4
mg, 0.13 mmol) and ligand 1e (30 mg, 0.13 mmol) were
dissolved in octane (15 ml) and refluxed for 1 h. The sol-
vent was removed under vacuum and the solid obtained
was eluted by column chromatography over SiO2, with
hexane–dichloromethane (5–0.5) as eluent to obtain
compound 2e in 70% yield (31 mg).
Compound [(CO)4Mn(5-MeOC6H3CH@NCH2Ph)]
(2b). Under an inert atmosphere, [MeMn(CO)5] (43
mg, 0.20 mmol) and ligand 1b (46 mg, 0.20 mmol) were
dissolved in octane (15 ml) and refluxed for 90 min. The
solution obtained was eluted by column chromatogra-
phy over SiO2, with hexane–dichloromethane (5–1) as
eluent to obtain compound 2b in 38% yield (30 mg).
Characterisation data for 2b. Anal. (%) Calcd. for
C19H14NO5Mn: C: 58.33, H: 3.61, N: 3.51. Found: C,
58.4; H, 3.6; N, 3.5. 1H NMR (200 MHz, CDCl3):
d = 3.89 (s, 3H, MeO); 4.85 (s, 2H, CH2Ph); 6.65 (dd,
1H, JHH = 8.2 Hz, JHH = 2.3 Hz, H4); 7.24–7.28 (m,
2H, aromatic); 7.34–7.39 (m, 3H, aromatic); 7.49 (d,
1H, JHH = 2.3 Hz, H6); 7.53 (d, 1H, JHH = 8.2 Hz,
H3); 8.28 (s, 1H, CH@N). IR (cmꢀ1): m(CO) 1941 m,
1981 m, 1992 s, 2079 w. FAB-MS, m/z: 391 [M], 364
[M–CO], 335 [M–2CO], 307 [M–3CO], 279 [M–4CO].
Compound [(CO)4Mn(5-NO2C6H3CH@NCH2Ph)]
(2c). Under an inert atmosphere, [MeMn(CO)5] (32.8
mg, 0.15 mmol) and ligand 1c (37.5 mg, 0.15 mmol)
were dissolved in octane (15 ml) and refluxed for 3
h. The solution obtained was eluted by column chro-
matography over SiO2, with hexane–dichloromethane
(5–3) as eluent to obtain compound 2c in 30% yield
(19 mg).
Characterisation data for 2e. Anal. (%) Calcd. for
C18H11ClNO4Mn: C: 54.65, H: 2.80, N: 3.54. Found:
1
C, 54.6; H, 3.0; N, 3.3. H NMR (200 MHz, CDCl3):
d = 4.92 (s, 2H, CH2Ph); 7.05 (d, 1H, JHH = 7.9 Hz,
H4); 7.17 (t, 1H, JHH = 7.8, H5); 7.27–7.31 (m, 2H, ar-
omatic); 7.36–7.44 (m, 3H, aromatic); 7.79 (d, 1H,
JHH = 7.2 Hz, H6); 8.78 (s, 1H, CH@N). IR (cmꢀ1):
m(CO) 1946 m, 1984 m, 1997 s, 2077 w. FAB-MS, m/z:
395 [M], 368 [M–CO], 339 [M–2CO], 311 [M–3CO],
283 [M–4CO].
Metallation of 2,6-Cl2C6H3CH@NCH2Ph. Under an
inert atmosphere, [MeMn(CO)5] (44.8 mg, 0.21 mmol)
and ligand 1f (56.3 mg, 0.21 mmol) were dissolved in oc-
tane (15 ml) and refluxed for 2 h. The solution obtained
was eluted by column chromatography over SiO2, with
hexane–dichloromethane (5–0.5) as eluent to obtain
compound 2e in the first eluted band and 3f in the sec-
ond band in 12% yield in both cases (10 and 11 mg,
respectively).
Characterisation data for 3f. Anal. (%) Calcd. for
C18H10Cl2NO4Mn: C: 50.26, H: 2.34, N: 3.20. Found:
1
C, 50.4; H, 2.4; N, 3.0. H NMR (200 MHz, CDCl3):
Characterisation data for 2c. Anal. (%) Calcd. for
C18H11N2O6Mn: C: 53.22, H: 2.73, N: 6.90. Found: C,
d = 4.62 (d, JHH = 2.6 Hz, 2H, CH2Ph); 6.89 (d, 1H,
JHH = 7.4 Hz, aromatic); 7.00 (t, 1H, JHH = 7.0 aro-
matic); 7.13 (t, 1H, JHH = 7.2 Hz, aromatic); 7.42 (m,
3H, aromatic); 7.75 (d, 1H, JHH = 7.4 Hz, aromatic);
8.86 (t, JHH = 2.6 Hz 1H, CH@N). IR (cmꢀ1): m(CO)
1942 m, 1979 m, 1991 s, 2072 w.
Metallation of 2,4,6-Me3C6H2CH@NCH2Ph. Under
an inert atmosphere, [MeMn(CO)5] (31.5 mg, 0.15
mmol) and ligand 1g (34.5 mg, 0.15 mmol) were dis-
solved in octane (15 ml) and refluxed for 2 h. The solu-
tion obtained was eluted by column chromatography
over SiO2, with hexane–dichloromethane (5–2) as eluent
to obtain compound 2g in the first eluted band (12 mg,
20% yield) and 3g in the second band in 22% yield (14
mg).
1
53.0; H, 2.5; N, 6.7. H NMR (200 MHz, CDCl3): d =
4.99 (s, 2H, CH2Ph); 7.27–7.29 (m, 2H, aromatic);
7.41–7.48 (m, 3H, aromatic); 7.69 (d, 1H, JHH = 8.2
Hz, H3); 7.97 (dd, 1H, JHH = 2.0 Hz, JHH = 8.2 Hz,
H4); 8.49 (s, 1H, CH@N); 8.74 (d, 1H, JHH = 2.0 Hz,
H6). IR (cmꢀ1): m(CO) 1954 m, 1991 m, 1999 s, 2081
w. FAB-MS, m/z: 407 [M], 379 [M–CO], 351 [M–
2CO], 323 [M–3CO], 295 [M–4CO].
Compound
[(CO)4Mn(4-ClC6H3CH@NCH2Ph)]
(2d). Under an inert atmosphere, [MeMn(CO)5] (27.4
mg, 0.13 mmol) and ligand 1d (30 mg, 0.13 mmol) were
dissolved in octane (15 ml) and refluxed for 90 min.
The solution obtained was eluted by column chroma-
tography over SiO2, with hexane–dichloromethane (5–
0.7) as eluent to obtain compound 2d in 45% yield
(24 mg).
Characterisation data for 3g. Anal. (%) Calcd. for
C21H18NO4Mn: C: 62.54, H: 4.50, N: 3.53. Found: C,

J. Albert et al. / Journal of Organometallic Chemistry 689 (2004) 4889–4896
4895
Table 2
3.5. X-ray crystallography
˚
Selected bond lengths [A] and angles [ꢁ] for 3g
Mn–C(3)
Mn–C(1)
Mn–C(2)
Mn–C(4)
Mn–N
1.801(3)
1.830(3)
1.843(3)
1.845(3)
2.062(2)
2.069(3)
1.141(4)
1.131(4)
1.137(4)
1.134(4)
1.271(3)
1.473(3)
1.380(4)
1.393(4)
1.393(5)
1.367(5)
1.385(4)
1.388(4)
1.501(4)
The crystal data, data collection and refinement pa-
rameters for the X-ray structures are listed in Table 2.
Data were collected in MAR345 diffractometer with a
image plate detector. Unit-cell parameters were deter-
mined from 16,264 reflections (3.22ꢁ < h < 31.78ꢁ) and
refined by least-squares method. Intensities were collected
with graphite monochromatized Mo Ka radiation.
40,734 reflections were measured in the range 3.22ꢁ <
h < 31.78ꢁ). 3665 of which were non-equivalent by
symmetry {Rint (on I) = 0.034}. 3114 reflections were
assumed as observed applying the condition I > 2r(I).
Lorentz-polarization but not absorption corrections
were made.
Mn–C(5)
O(1)–C(1)
O(2)–C(2)
O(3)–C(3)
O(4)–C(4)
N–C(12)
N–C(11)
C(5)–C(6)
C(5)–C(10)
C(6)–C(7)
C(7)–C(8)
C(8)–C(9)
C(9)–C(10)
C(10)–C(11)
The structure was solved by Direct methods, using
SHELXS computer program [17] and refined by full-
matrix least-squares method. The function minimised
P
2
2 2
was
w[jFoj ꢀ jFcj ] , where w = [r2(I) + (0.0636P)2
C(3)–Mn–C(1)
C(3)–Mn–C(2)
C(1)–Mn–C(2)
C(3)–Mn–C(4)
C(1)–Mn–C(4)
C(2)–Mn–C(4)
C(3)–Mn–N
93.53(13)
87.77(13)
93.12(14)
87.78(14)
98.56(15)
167.74(14)
173.19(12)
92.42(11)
95.21(11)
88.07(12)
94.62(12)
170.07(12)
81.54(12)
87.44(13)
79.81(10)
119.6(2)
+ 1.0799P]ꢀ1, and P = (jFoj + 2jFcj )/3. f, f0 and f00
were taken from International Tables of X-Ray Crystal-
lography [18]. All H atoms were located from a differ-
ence synthesis and refined with an overall isotropic
temperature factor.
2
2
C(1)–Mn–N
C(2)–Mn–N
C(4)–Mn–N
4. Supplementary material
C(3)–Mn–C(5)
C(1)–Mn–C(5)
C(2)–Mn–C(5)
C(4)–Mn–C(5)
N–Mn–C(5)
Crystallographic data for 3g have been deposited with
the Cambridge Crystallographic data Centre as supple-
mentary publication number: CCCD 238164. Copies of
the data can be obtained free of charge on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ (fax:
+44-1223-336-033; e-mail: deposit@ccdc.cam.ac.uk).
C(12)–N–C(11)
C(12)–N–Mn
C(11)–N–Mn
O(1)–C(1)–Mn
O(2)–C(2)–Mn
O(3)–C(3)–Mn
O(4)–C(4)–Mn
C(6)–C(5)–C(10)
N–C(11)–C(10)
N–C(12)–C(13)
126.47(17)
113.32(17)
177.1(3)
174.0(3)
179.1(3)
Acknowledgements
176.1(3)
116.7(3)
This work was supported by the Ministerio de Cien-
´
108.3(2)
128.7(2)
cia y Tecnologıa and ERDF, European Regional Devel-
opment Found, (project: BQU2003-00906) and by the
Comissionat per a Universitats i Recerca (project:
2001SGR-00054).
62.5; H, 4.9; N, 3.5. 1H NMR (200 MHz, CDCl3):
d = 2.13 (s, 6H, Me); 2.32 (s, 3H, Me); 4.45 (s, 2H,
CH2Ph); 6.86 (d, 1H, JHH = 7.5 H6); 6.92 (s, 2H, aro-
matic); 6.98 (t, 1H, JHH = 7.5 H5); 7.12 (t, 1H,
JHH = 7.2 H4); 7.74 (d, 1H, JHH = 7.2 H3); 8.99 (s,
1H, CH@N). IR (cmꢀ1): m(CO) 1935 m, 1985 s, 2069
w. FAB-MS, m/z: 402 [M], 376 [M–CO], 347 [M–
2CO], 319 [M–3CO], 292 [M–4CO].
References
[1] (a) M.I. Bruce, Angew. Chem. Int. Ed. Engl. 16 (1977) 73;
(b) G.R. Newkome, W.E. Puckett, V.K. Gupta, G.E. Kiefer,
Chem. Rev. 86 (1986) 451;
(c) I. Omae, Coord. Chem. Rev. 83 (1988) 137;
(d) V.V. Dunina, O.A. Zalevskaya, V.M. Potapov, Russ. Chem.
Rev. 57 (1988) 250;
1
Characterisation data for 2g. H NMR (200 MHz,
CDCl3): d = 2.06 (s, 2H, CH2Mn); 2.13 (s, 3H, Me);
2.25 (s, 3H, Me); 4.86 (s, 2H, CH2Ph); 6.58 (s, 1H, aro-
matic); 6.91 (s, 1H, aromatic); 7.28–7.39 (m, 5H, aro-
matic); 8.35 (s, 1H, CH@N). IR (cmꢀ1): m(CO) 1927
m, 1969 m, 1979 s, 2063 w.
(e) A.D. Ryabov, Chem. Rev. 90 (1990) 403.
[2] (a) J. Vicente, I. Saura Llamas, J. Cuadrado, M.C. Ramirez de
Arellano, Organometallics 22 (2003) 5513;
(b) J. Vicente, I. Saura Llamas, M.G. Palin, P.G. Jones, M.C.
Ramirez de Arellano, Organometallics 16 (1997) 826;

4896
J. Albert et al. / Journal of Organometallic Chemistry 689 (2004) 4889–4896
´
(e) J. Albert, R. Ceder, M. Gomez, J. Granell, J. Sales,
Organometallics 11 (1992) 1536.
(c) A.D. Ryabov, Synthesis (1985) 233;
(d) M. Pfeffer, Recl. Trav. Chim. Pays Bas 109 (1990) 567;
(e) P. Espinet, M.A. Esteruelas, L.A. Oro, J.L. Serrano, E. Sola,
Coord. Chem. Rev. 117 (1992) 215;
[7] (a) T.G. Richmond, Coord. Chem. Rev. 105 (1990) 221;
(b) J.L. Kiplinger, T.G. Richmond, C.E. Osterberg, Chem. Rev.
94 (1994) 373;
´
´
(f) C. Navarro-Ranninger, I. Lopez-Solera, J.M. Perez, J.R.
Masaguer, C. Alonso, Appl. Organomet. Chem. 7 (1993) 57;
(g) M. Camargo, P. Dani, J. Dupont, R.F. de Souza, M. Pfeffer,
I. Tkatchenko, J. Mol. Catal. 109 (1996) 127;
´
(c) M. Crespo, M. Martınez, J. Sales, J. Chem. Soc. Chem.
Comm. (1992) 822;
(d) M. Crespo, M. Martınez, J. Sales, Organometallics 12 (1993)
´
(h) R. Navarro, E.P. Urriolabeitia, C. Cativiela, M.D. Diaz de
´
Villegas, M.P. Lopez, E. Alonso, J. Mol. Catal. 105 (1996) 111.
4297;
(e) J. Albert, J. Barro, J. Granell, J. Organomet. Chem. 408 (1991)
115;
[3] (a) R.L. Bennet, M.I. Bruce, B.L. Goodall, M.Z. Iqbal, F.G.A.
Stone, J. Chem. Soc. Dalton Trans. (1972) 1787;
(b) M.I. Bruce, B.L. Goodall, F.G.A. Stone, J. Chem. Soc.
Dalton Trans. (1978) 687;
´
(f) R. Ceder, J. Granell, G. Muller, M. Font-Bardıa, X. Solans,
Organometallics 14 (1995) 5544.
[8] (a) C. Navarro-Raninger, I. Lopez-Solera, A. Alvarez-Valdes,
´ ´
J.M. Rodrıguez-Ramos, J.R. Masaguer, J.L. Garcıa-Ruano,
´
´
(c) A. Bo¨hm, K. Su¨nkel, K. Polborn, W. Beck, J. Organomet.
Chem. 552 (1998) 237;
´
(d) J.M. Vila, M. Gayoso, M.T. Pereira, M. Lopez Torres, J.J.
Organometallics 12 (1993) 4104;
(b) A. Crispini, M. Ghedini, J. Chem. Soc. Dalton Trans (1997)
75.
´ ´
Fernandez, A. Fernandez, J.M. Ortigueira, J. Organomet. Chem.
´
[9] M. Crespo, C. Grande, A. Klein, M. Font-Bardıa, X. Solans, J.
Organomet. Chem. 563 (1998) 179.
506 (1996) 165;
(e) C. Morton, D.J. Duncalf, J.P. Rourke, J. Organomet. Chem.
530 (1997) 19;
´
[10] (a) M. Gomez, J. Granell, M. Martınez, J. Chem. Soc. Dalton
´
(f) R.M. Ceder, J. Sales, X. Solans, M. Font-Altaba, J. Chem.
Soc. Dalton Trans. (1986) 1351;
Trans. (1998) 37;
´
(b) M. Gomez, J. Granell, M. Martınez, Organometallics 16
´
(g) M. Pfeffer, E.P. Urriolabeitia, J. Fischer, Inorg. Chem. 34
(1995) 643;
(1997) 2539.
[11] (a) J. Albert, M. Gomez, J. Granell, J. Sales, X. Solans,
´
(h) J.P. Djukic, A. Maisse, M. Pfeffer, J. Organomet. Chem. 567
(1998) 65;
Organometallics 9 (1990) 1405;
(b) J. Albert, J. Granell, A. Luque, M. Font-Bardia, X. Solans, J.
Organomet. Chem. 545 (1997) 131;
(i) J.P. Djukic, A. Maisse, M. Pfeffer, A. de Cian, J. Fischer,
Organometallics 16 (1997) 657;
´
(j) A. Suarez, J.M. Vila, M.T. Pereira, E. Gayoso, M. Gayoso, J.
(c) J. Albert, J. Granell, J. Sales, Organometallics 14 (1995)
1293.
Organomet. Chem. 335 (1987) 359;
(k) J.M. Vila, M. Gayoso, M.T. Pereira, M. Lopez Torres, G.
[12] J. March, Advanced Organic Chemistry, John Wiley and Sons,
New York, 1985 pp. 576–607.
´
´
Alonso, J.J. Fernandez, J. Organomet. Chem. 445 (1993) 287;
(l) A. de Cian, J.P. Djukic, J. Fischer, M. Pfeffer, K.H. Doetz,
Chem. Commun. (2002) 638.
[13] R.G. Miller, R.D. Stauffer, D.R. Fahey, D.R. Parnell, J. Am.
Chem. Soc. 92 (1970) 1511.
´
[14] (a) J. Albert, J. Granell, J. Mınguez, G. Muller, D. Sainz, P.
Valerga, Organometallics 16 (1997) 3561;
[4] The detection of ethanal by GC-MS supports this migratory
insertion step, see reference [3e].
(b) J. Bernstein, J. Chem. Soc. Perkin Trans. (1972) 946;
(c) T. Inabe, I. Gaultier-Luneau, N. Hoshino, K. Okinawa, H.
Okamoto, T. Mitani, U. Nagashima, Y. Maruyama, Bull. Chem.
Soc. Jpn. 64 (1991) 801;
[5] (a) G. Tennant, in: D. Barton, W.D. Ollis (Eds.), Comprehensive
Organic Chemistry, vol. 2, Pergamon, Oxford, 1979 Chapter 8;
(b) S. Patai, The Chemistry of the Carbon-Nitrogen Double Bond,
John Wiley and Sons, Chichister, 1970 pp. 364–372, 405–408.
´
(d) M. Crespo, M. Martınez, J. Sales, X. Solans, M. Font-Bardia,
´
[6] (a) J. Albert, J. Granell, R. Moragas, M. Font-Bardıa, X. Solans,
Organometallics 11 (1992) 1288.
[15] M. Crespo, J. Granell, X. Solans, M. Font-Bardia, Organometal-
lics 21 (2002) 5140.
J. Organomet. Chem. 522 (1996) 59;
(b) J. Albert, J. Granell, R. Moragas, J. Sales, M. Font-Bardıa,
´
X. Solans, J. Organomet. Chem. 494 (1995) 95;
(c) G. De Munno, M. Ghedini, F. Neve, Inorg. Chim. Acta 239
(1995) 155;
[16] R.J. Mckinney, S.S. Crawford, Inorg. Synth. 26 (1989) 156.
[17] G.M. Sheldrick, Shelks97. A computer program for determination
of crystal structure, Univeristy Go¨ttingen, Germany, 1997.
[18] International Tables of X-Ray Crystallography (1974) Ed. Kyn-
och press, Vol. IV, pp. 99–100, 149.
´
(d) R. Bosque, C. Lopez, J. Sales, J. Organomet. Chem. 498
(1995) 147;