Activation of σ(C-H) bonds of [Fe{(η5-C5 H4)-C(Me)=N-N=C(H)(C6H3-2,6-R)} 2] (with R=Cl or H) promoted by palladium(II)

Article abstract of DOI:10.1016/S0022-328X(03)00137-2

The synthesis, characterisation and the study of the reactivity of the novel and bifunctional ferrocenyl Schiff bases [Fe{(η⁵-C₅H₄)-C(Me)=N-N=C(H) (C₆H₃-2,6-R₂)}₂] (with R=Cl or H) with palladium(II) salts under different experimental conditions are reported. The treatment of Na₂ [PdCl₄], Na(CH₃COO)·3H₂O and the corresponding ligand [Fe{(η⁵ -C₅H₄)-C (Me)=N-N=C(H)(C₆H₃ -2,6-R₂ }₂] (with R=Cl or H) (in a 2:2:1 molar ratio) in methanol for 6 days followed by the addition of triphenylphosphine (PPh₃), and a SiO₂ column chromatography, allowed the isolation of the two isomers (meso- and D,L - forms) of the heterotrimetallic complexes of general formula [Pd₂{Fe[(η⁵-C₅ H₃)-C(Me)=N-N-C(H)(C₆H₅-2,6- R₂)]₂}Cl₂(PPh₃)₂], (with R = Cl or H).

Full text of DOI:10.1016/S0022-328X(03)00137-2

Journal of Organometallic Chemistry 672 (2003) 34ꢀ42
/
www.elsevier.com/locate/jorganchem
Activation of s(Cꢀ
/
H) bonds of [Fe{(h5-C5H4)ꢀ
Cl or H) promoted by palladium(II)
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
C(H)(C6H3ꢀ2,6-R)}2] (with Rꢁ
/
/
Concepcio´n Lo´pez a,*, Ramo´n Bosque a, Javier Arias a, Emilia Evangelio a,
Xavier Solans b, Merce` Font-Bard´ıa b
a Departament de Qu´ımica Inorga`nica, Facultat de Qu´ımica, Universitat de Barcelona, Mart´ı i Franque`s 1-11, 08028 Barcelona, Spain
b Departament de Cristal.lografia, Mineralogia i Dipo`sits Minerals, Facultat de Geologia, Universitat de Barcelona, Mart´ı i Franque`s s/n, 08028
Barcelona, Spain
Received 17 December 2002; received in revised form 12 February 2003; accepted 12 February 2003
Abstract
The synthesis, characterisation and the study of the reactivity of the novel and bifunctional ferrocenyl Schiff bases [Fe{(h5-
C5H4)ꢀC(Me)ꢀNꢀNꢀC(H)(C6H3ꢀ2,6-R2)}2] (with RꢁCl or H) with palladium(II) salts under different experimental conditions
are reported. The treatment of Na2[PdCl4], Na(CH3COO)× C(Me)ꢀNꢀNꢀ
3H2O and the corresponding ligand [Fe{(h5-C5H4)ꢀ
C(H)(C6H3ꢀ2,6-R2)}2] (with RꢁCl or H) (in a 2:2:1 molar ratio) in methanol for 6 days followed by the addition of
triphenylphosphine (PPh3), and a SiO2 column chromatography, allowed the isolation of the two isomers (meso- and - forms) of
the heterotrimetallic complexes of general formula [Pd2{Fe[(h5-C5H3)ꢀ
C(Me)ꢀNꢀNꢀC(H)(C6H5ꢀ2,6-R2)]2}Cl2(PPh3)2], (with
RꢁCl or H).
# 2003 Elsevier Science B.V. All rights reserved.
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D,L
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Keywords: Activation of CꢀH; Iron; Schiff base; Palladium
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1. Introduction
cyclopalladation of the 1,1?-ferrocenylhydrazone:
NꢀNHꢀ(CO2Me)}2] (1) (Fig.
1) [5], while the others were focussed on the cyclopalla-
[Fe{(h5-C5H4)ꢀ
/
C(Me)ꢀ
/
/
/
Palladium(II) compounds containing (C,N)ꢂ biden-
tate ligands have attracted great interest in recent years
[1] due to their potential applications in a wide variety of
areas [2,3] including their use as precursors for organic
or organometallic synthesis [3]. Among all cyclopalla-
dated derivatives reported so far, the most widely
studied systems are those containing [C(sp2, aryl),
N]ꢂ, [C(sp3), N]ꢂ or [C(sp2, ferrocene), N]ꢂ chelate
ligands. Some examples of bis(cyclopalladated) deriva-
dation of 1,1?-ferrocenyldiimines of general formula:
[Fe{(h5-C5H4)ꢀ
/
C(R)ꢀ
CH2C6H5 (2a), RꢁMe, R?ꢁ
Me (3b)} (Fig. 1) [6]. All of these ligands (1ꢀ
one type of s(CꢀH) bond susceptible to undergo
/
Nꢀ
/
R?}2] {with Rꢁ
C6H5 (3a) or C6H4ꢀ
3) had only
/
H, R?ꢁ
/
/
/
/4-
/
/
palladation, and their reactions with Na2[PdCl4] in the
presence of sodium acetate lead to the heterotrimetallic
complexes containing two five-membered palladacycles
with a s[Pdꢀ
/
C(sp2, ferrocene)] bond fused with the
tives arising from the activation of s[C(sp2, aryl)ꢀ
/
H]
pentagonal rings of the ferrocenyl fragment [6]. In the
view of these results and as a part of a project directed
towards the synthesis and study of the potential
applications of cyclopalladated compounds containing
bonds have also been reported in the literature [4].
However, examples involving the cyclopalladation of
the two rings of a ferrocenyl ligand are scarce [5,6]. To
our knowledge only three articles have been published
on this field [5,6], one of them involved the double
s[Pdꢀ
whether the replacement of the R? group in [Fe{(h5-
C5H4)ꢀC(R)ꢀNꢀR?}2] (2ꢀ3) by an additional ꢀNꢀ
CH(Rƒ)ꢀ containing an Rƒ group susceptible to metal-
late (i.e. a phenyl ring) could be important to determine:
(a) the nature of the s(CꢀH bond) to be activated; (b)
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C(sp2, ferrocene)] bonds we decided to elucidate
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* Corresponding author. Tel.: ꢃ
725.
E-mail address: conchi.lopez@qi.ub.es (C. Lo´pez).
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34-93-4021-274; fax: ꢃ34-93-4907-
/
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0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00137-2

C. Lo´pez et al. / Journal of Organometallic Chemistry 672 (2003) 34ꢀ
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Fig. 1. Schematic view of the bifunctional ferrocenyl Schiff bases used in bis(cyclopalladation) reactions (1ꢀ/3), together with that of the two ligands
under study (4a and 4b).
the number of palladacycles contained in the final
products; or (c) their sizes. With this aim in this paper
or a ferrocenyl group [8], which consists on the
condensation of the ferrocenylamine [(h5-C5H4)Fe-
we report the synthesis of [Fe{(h5-C5H4)ꢀ
/
C(Me)ꢀ
/
Nꢀ
/
{(h5-C5H4)ꢀ
/
(CH2)nꢀ
amounts of the corresponding aldehyde or ketone in
refluxing ethanol. When [Fe{(h5-C5H4)ꢀ
C(Me)ꢀNꢀ
NH2}2] [7] was treated with (2,6-R2ꢀC6H3)C(H)O
(RꢁCl or H) in a 1:2 molar ratio in ethanol under
/
NH2}] (nꢁ1 or 2) and equimolar
/
Nꢀ
/
C(H)(C6H3ꢀ
/
2,6-R2)}2] {with Rꢁ
/
Cl (4a) or H
(4b)} and the results obtained from their reactions
/
/
/
with palladium(II) salts.
/
/
reflux for 2 h (Scheme 1) followed by the slow
evaporation of the solvent, compounds [Fe{(h5-
2. Results and discussion
C5H4)ꢀ
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
C(H)(C6H3ꢀ
/
2,6-R2)}2] {RꢁCl
/
(4a) or H (4b)} were obtained as deep red microcrystal-
line products in a fairly good yield (65%).
2.1. The ligands
Compounds 4 are highly soluble in CH2Cl2 and
CHCl3, practically insoluble in n-hexane and they
hydrolyse slowly in water. These new ligands have
been characterised by elemental analyses, infrared and
mono- and two-dimensional NMR spectroscopies. The
elemental analyses (see Section 3) were consistent with
Compounds
(C6H3ꢀ2,6-R2)}2] with Rꢁ
prepared by condensation of the corresponding alde-
hyde and [Fe{(h5-C5H4)ꢀ
C(Me)ꢀNꢀNH2}2] [7] in a 2:1
[Fe{(h5-C5H4)ꢀ
Cl (4a) or H (4b) were
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
C(H)-
/
/
/
/
/
molar ratio in refluxing ethanol for 2 h (Scheme 1),
using the procedure described before for the mono-
functional ferrocenyl Schiff bases of general formula:
those expected for [Fe{(h5-C5H4)ꢀ
C(H)(C6H3ꢀ2,6-R2)}2] {RꢁCl (4a) or H (4b)}. The
most relevant feature observed in the infrared spectra is
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
[(h5-C5H4)Fe{(h5-C5H4)ꢀ
nꢁ
/
(CH2)Nꢀnꢀ
/
C(R2)R3}] where
/
/
/
1 or 2; R2 is H or Me and R3 represents a phenyl
Scheme 1. (i) 2,6-Dichlorobenzaldehyde (for 4a) or benzaldehyde (for 4b) in a 1:2 molar ratio in refluxing ethanol for 2 h. (ii) Na2[PdCl4],
3H2O, in methanol, at room temperature for 6 days. (iii) Filtration and treatment of the solid with PPh3 in CH2Cl2. (iv) SiO2-column
chromatography using CH2Cl2 as the eluant, in this process small amounts of trans-[PdCl2(PPh3)2] were also isolated as a by-product in the two cases
Na(CH3COO)×
/
(see text).

36
C. Lo´pez et al. / Journal of Organometallic Chemistry 672 (2003) 34ꢀ42
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the presence of a intense band in the range 1600ꢀ
cmꢂ1 which is ascribed to the stretching of the two
ÈCꢀNꢀ functional groups.
Proton NMR spectra of 4 showed a singlet in the
range 8.30ꢀ8.70 ppm, which is ascribed, according to
the literature, to the imine proton. For compound 4a
this resonance appeared at lower fields (dꢁ8.60 ppm)
than for 4b (dꢁ8.38 ppm). This finding is similar to
that reported for the monofunctional ferrocenylimines:
[{(h5-C5H5)ꢀFe{(h5-C5H4)ꢀ
(CH2)2ꢀNꢀC(H)(R?)}]
with Rꢁ2,6-C6H3Cl2 (dꢁ8.38 ppm) or C6H5 (dꢁ
ppm) [8] which has been attributed to the existence of a
weak hydrogen interaction between one of the chloro
groups on the aryl ring and the imine proton.
Ligand 4a has also been characterised by X-ray
diffraction. The molecular structure of 4a together
with the atom labelling scheme is depicted in Fig. 2,
and a selection of bond lengths and angles is presented
in Table 1.
/
1700
Table 1
Selected bond lengths (A) and bond angles (8) for [Fe{(h -C5H4)ꢀ
Nꢀ C(H)(2,6-Cl2 ꢀC6H3)}2] (4a) (standard deviation para-
5
˚
/
C(Me)ꢀ
/
/
Nꢀ
/
/
/
/
meters are given in parenthesis)
Bond lengths
/
N(1)ꢀ
Cl(1)ꢀ
C(9)ꢀC(10)
C(10)ꢀ
C(12)ꢀ
Feꢀ
C a
/
C(6)
1.282(3)
1.739(2)
1.396(3)
1.380(3)
1.373(4)
2.045(9)
N(2)ꢀ
Cl(2)ꢀ
C(9)ꢀC(14)
C(11)ꢀ
C(13)ꢀ
Cꢀ
C a
/
C(8)
1.237(3)
1.727(3)
1.402(3)
1.386(4)
1.383(4)
1.416(11)
/
C(10)
/C(14)
/
/
/
/
/
C(11)
C(13)
/C(12)
/
/C(14)
/
/
/
/
/
/
Bond angles
C(6)ꢀN(1)ꢀ
N(1)ꢀC(6)ꢀ
C(5)ꢀC(6)ꢀ
C(9)ꢀC(10)ꢀ
C(9)ꢀC(14)ꢀ
/
/
/
8.04
/
/
N(2)
C(5)
113.7(2)
116.0(2)
119.0(2)
C(8)ꢀ
N(1)ꢀ
N(2)ꢀ
/
N(2)ꢀ
C(6)ꢀ
C(8)ꢀ
/
N(1)
C(7)
C(9)
112.7(2)
125.0(2)
125.5(2)
116.3(2)
116.2(2)
/
/
/
/
/
/C(7)
/
/
/
/Cl(1)
120.03(18) C(11)ꢀ
121.65(19) C(13)ꢀ
/C(10)ꢀ
/
Cl(1)
Cl(2)
/
/Cl(2)
/C(14)ꢀ
/
a
Average value for the ‘Fe(C5H4 ꢀ)2’ moiety.
/
N(1) unit. All the atoms belonging to the C5H4 ring, the
functional groups and the phenyl ring are nearly co-
planar [11]
The structure consists on discrete molecules of
[Fe{(h5-C5H4)ꢀ
/
C(Me)ꢀ
separated by van der Waals contacts. In each molecule
the two ‘{(h5-C5H4)ꢀ
C(Me)ꢀNꢀNꢀC(H)(C6H3 ꢀ2,6-
Cl2)}’ fragments are related by a symmetry element.
The values of the C(7)ꢀC(6)ꢀN(1)ꢀN(2) [1.768] and
N(1)ꢀN(2)ꢀC(8)ꢀC(9) [173.568] indicate that the methyl
/
Nꢀ
/
Nꢀ
/
C(H)(C6H3 ꢀ2,6-Cl2)}2]
/
The Cl(1)ꢀ
/
C(10) bond length is slightly larger
[1.739(2) A], if significant, than the Cl(2)ꢀC(14) bond
distance [1.727(3) A] while the Cl(1)ꢀ ꢀ ꢀH(8) distance
/
/
/
/
/
˚
/
˚
/
/
/
˚
[2.48(6) A] is clearly smaller than the sum of the van der
/
/
/
˚
˚
Waals radii of these atoms (Cl, 1.75 A and H, 1.20 A)
group and the aryl ring are on the same side of the plane
defined by the atoms C(6), N(1), N(2) and C(8). The
˚
C(7) atom deviates by ca. 0.01A from the plane defined
[12], thus suggesting a weak C(8)ꢀ
/
H(8)ꢀ ꢀ ꢀCl(1) intra-
molecular interaction. A similar type of interaction has
been found in the closely related monofunctional Schiff
bases holding ferrocenyl units such as [(h5-C5H5)Fe-
by the C(5), C(6) and N(1) atoms. A similar type of
distortion has also been reported for the monofunc-
tional ferrocenylimines of the type [(h5-C5H5)Fe{(h5-
{(h5-C5H4)ꢀ
/
CH2ꢀ
/
Nꢀ
/
C(H)(C6H3ꢀ
/
2,6-Cl2)}] [8c]. Bond
lengths and angles of the ‘Fe(h5-C5H4ꢀ
consistent with those reported for most of ferrocene
/
)2’ fragment are
C5H4)ꢀ
groups [9]. The cyclopentadienyl ring is planar [10]
and forms an angle of ca. 8.288 with the C(5)ꢀC(6)ꢀ
/
C(Me)ꢀ
/
Nꢀ
/
Rƒ}] with Rƒꢁ
/
phenyl or benzyl
/
/
derivatives [13].
Fig. 2. Molecular structure and atom labelling scheme for ligand [Fe{(h5-C5H4)ꢀ
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
C(H)(2,6-Cl2 ꢀC6H3)}2] (4a).
/

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2.2. Activation of s(Cꢀ
[Fe{(h5-C5H4)ꢀ
C(Me)ꢀ
R2)}2] with RꢁCl (4a) or H (4b)
/
H) bonds of compounds
/
/
NꢀNꢀC(H)(C6H3ꢀ2,6-
/
/
/
/
In a first attempt to achieve the cyclopalladation of
ligands 4, we decided to use the procedure described
before for the metallation of the monofunctional
ferrocenyl Schiff bases of general formula: [{(h5-
C5H5)Fe{(h5-C5H4)ꢀ
Ph and R?ꢁ
which is based on the treatment of equimolar amounts
of the free ligand, Na2[PdCl4] and Na(CH3COO)×3H2O
in methanol at room temperature [9,14,15], produces the
/
C(R)ꢀ
/
Nꢀ
/
R?}] with RꢁH, Me or
/
/
phenyl or a benzyl group. This method,
/
di-m-chloro-bridged
cyclopalladated
C(R)ꢀNꢀ
derivatives:
R’]}(m-Cl)]2.
[Pd{(h5-C5H5)Fe[(h5-C5H3)ꢀ
/
/
/
Due to the low solubility of these dimers in most
common solvents, they are difficult to characterise and
they are usually treated with phosphine ligands to
produce the monomeric derivatives: [Pd{(h5-
C5H5)Fe[(h5-C5H3)ꢀ
more soluble.
The reaction of ligand 4a with Na2[PdCl4] and
Na(CH3COO)×3H2O in a 1:2:2 molar ratio in methanol
/
C(R)ꢀ
/
NꢀR?]}Cl(PPh3)] which are
/
/
at room temperature for 6 days produced a nearly black
solid and its subsequent treatment with triphenylpho-
sphine in CH2Cl2 at room temperature for 1 h followed
by concentration of the solution gave a deep purple
solid. Its 31P{1H}-NMR spectrum showed three singlets
at dꢁ38.7, 37.6 and 23.2 ppm. The chemical shift of the
/
Fig. 3. Partial views of the 1H-NMR spectra of 5a (A) and of the two-
dimensional {31Pꢀ1
H}-NMR spectrum of 5a (B). (The signals marked
in italics correspond to the meso- form of 5a.)
signal at lower higher fields suggested the presence of
the coordination complex trans-[PdCl2(PPh3)2] [16].
Due to the low solubility of trans-[PdCl2(PPh3)2] in
CH2Cl2 it was easily removed from the mixture by
dissolving the crude of the reaction in the minimum
amount of CH2Cl2. The elemental analyses of the solid
obtained by concentration of the resulting filtrate were
/
methyl groups. The two dimensional 31Pꢀ1
H-NMR
/
spectrum is presented in Fig. 3B, and shows that one
of the signals due to the phosphorous has cross peaks
with one of the singlets due to the proton of the imine
group and with two of the six singlets detected in the
consistent with those expected for [Pd2{Fe[(h5-C5H3)ꢀ
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
C(H)(C6H3ꢀ2.6-Cl2)]2}Cl2(PPh3)2] (5a),
/
but its 1H-, 13C{1H}- and 31P{1H}-NMR were more
complex than expected. In the 31P{1H}-NMR spectrum,
range 3.00ꢀ5.00 ppm and with one of the resonances
/
due to the methyl groups and a similar result is obtained
for the signal due to the other 31P nucleus.
The doubling of the signals observed in the NMR
spectra could be indicative of the presence of two species
in solution. However, no evidences for any interchange
two singlets of identical intensity at dꢁ38.7 and 37.6
/
ppm were observed, and the position of these signals
was consistent with those reported for cyclopalladated
complexes of general formula: [Pd{[(h5-C5H3)ꢀ
/
C(R)ꢀ
H, Me or
phenyl benzyl or naphthyl) in which
/
1
between them was obtained from the Hꢀ1
/
H-NOESY
experiment at room temperature. On the other hand, it
Nꢀ
/
R?]Fe(h5-C5H5)}Cl(PPh3)] (with Rꢁ
/
C6H5 and R?ꢁ
/
is well known that the activation of a s(Csp2,
ferroceneꢀH) bonds in the N-donor ferrocenyl ligands
the PPh3 and the metallated carbon are in a cis-
arrangement [12]. This is the typical result of the
reaction of palladacycles derived from (C,N)ꢂ bidentate
ligands and PPh3, due to the so-called transphobia effect
[17]. The proton NMR spectrum showed two super-
imposed sets of signals (Fig. 3A) and in particular the
most relevant feature observed in the spectrum was the
/
introduces planar chirality, and consequently for ligands
4, the cyclopalladation of the two rings may produce
two stereoisomers {meso- and D,L- forms} (Scheme 2).
In order to confirm these findings we decided to try to
separate the two isomers and to characterise them
separately.
presence of six singlets in the range 3.0ꢀ5.0 ppm, two
/
In a first attempt to achieve the separation of the two
isomers compound 5a was passed through a short SiO2
resonances due to the imine protons and two singlets in
the higher fields area assigned to the protons of the

38
C. Lo´pez et al. / Journal of Organometallic Chemistry 672 (2003) 34ꢀ42
/
Scheme 2. Rꢁ
/
Cl or H. (i) Cyclopalladation of one of the rings. (ii) Cyclopalladation of the other ring. (iii) Rotation around the Cꢀ
C1 bond of the
/
non-metallated ring. (iv) Palladation of the other ring.
column chromatography using a CH2Cl2ꢀ
/
CH3OH
product in the reaction described above. The position of
the two signals at dꢁ36.0 and 37.6 ppm were very
similar to those of 5a and could be indicative of the
(100:0.05) mixture as eluant. This produced the release
of a band which lead after concentration to a deep red
solid. Its proton NMR spectrum showed only four
/
presence of the two isomers of the bis(cyclopalladated)
signals of relative intensities 3:1:1:1 in the region 2.0ꢀ
/
complex
[Pd2{Fe[(h5-C5H3)ꢀ
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
C(H)-
5.0. The former was assigned to the methyl protons
while the remaining signals correspond to the protons of
the C5H3 rings. The position of these signals as well as
the magnitude of their shifts compared with that of the
free ligand were very similar to those observed for the
meso- forms of the bis(metallated) complexes derived
(C6H5)]2}Cl2(PPh3)2] (5b). In addition, the 1H-NMR
spectrum of the crude material indicated also the
presence of the free ligand. The use of an SiO2-column
chromatography allowed the isolation of 4b, trans-
[PdCl2(PPh3)2] and complex 5b. The subsequent separa-
tion of the two isomeric forms of 5b was achieved using
the same procedure as described for 5a, and meso- and
from ligands 2: [Pd{Fe{(h5-C5H3)ꢀ
The 31P{1H}-NMR spectrum showed only one signal
at dꢁ37.6 ppm. These findings suggested that the first
/
C(H)ꢀ
/
NꢀR?)}2].
/
D
,L
- forms were isolated in a molar ratio of 1.10. Also in
this case the meso- form- exhibited higher Rf value than
the - form.
It is worth to mention that although ligand 4b
contains two different types of s(CꢀH) bonds suscep-
tible to activate {a s[C(sp2, ferrocene)ꢀ
H] and a
H] bond} the cyclopalladation at the
/
eluted band contained the meso- form of 5a. The second
component was isolated after the elution with a
D,L
CH2Cl2ꢀ
This deep-purple solid was identified according to its
NMR data as the - form of 5a.
/
CH3OH (100:0.1) mixture and the work up.
/
/
D,
L
s[C(sp2, phenyl)ꢀ
/
More complex were the results obtained when the
reaction was performed under identical experimental
conditions but using ligand 4b as starting material. In
this case, the 1H- and 31P{1H}-NMR spectra of the
crude of the reaction were more complex and suggested
that it contained a mixture of several compounds. In
particular, the 31P{1H}-NMR spectrum showed three
ferrocenyl unit occurs and no evidences of the formation
of any other palladacycle with one or two s[C(sp2,
1
phenyl)ꢀ
/
H] bonds was detected by H- and 31P-NMR
spectroscopy. This finding is consistent with the higher
proclivity of the ferrocene derivatives to undergo
electrophilic attacks [17].
In a first attempt for the synthesis of the monome-
tallated derivatives the reactions between the equimolar
amounts of corresponding ligand 1, Na2[PdCl4] and
singlets at dꢁ
at (dꢁ23.2 ppm) was indicative of the presence of
trans-[PdCl2(PPh3)2], which was also formed as a by-
/37.6, 36.0 and 23.2 ppm. The later signal
/
Na(CH3COO)×/3H2O in methanol at room temperature

C. Lo´pez et al. / Journal of Organometallic Chemistry 672 (2003) 34ꢀ
/42
39
were also studied. However, in the two cases, no
evidences of the formation of the complexes arising
undergo the cyclopalladation to produce the meso- form
(Scheme 2). However, if this ring rotates around the C1ꢀ
Cipso bond prior to the metallation, this would lead to
the - form (Scheme 2). Thus, the presence of bulky
groups in the vicinity of the non-metallated ring should
hinder the free rotation around the C1ꢀ
Cipso bond, and
consequently a decrease of molar ratio meso-/ - form
should be expected. The similarity between the meso-/
- form molar ratios [1.02 (for 5a) and 1.10 (for 5b)]
for compounds 5, suggests that once the metallation of
one of the rings occurs, the rotation around the C1ꢀ
/
from the activation of only one s[Csp2, ferrocene)ꢀ
bond were detected by NMR.
/H]
D,L
2.3. Conclusions
/
D,L
The results reported in this work have allowed the
isolation and characterisation of the two isomeric
D,L
forms (meso- and
compounds: [Pd2{Fe[(h5-C5H3)ꢀ
(C6H5ꢀ2,6-R2)]2}Cl2(PPh3)2], {with Rꢁ
(5b)} in a nearly equimolar ratio formed by the
activation of two s[C(sp2, ferrocene)ꢀ
H] bonds belong-
ing to two different ‘C5H4-’ rings of the ligands bases
[Fe{(h5-C5H4)ꢀ
C(Me)ꢀNꢀNꢀC(H)(C6H3 ꢀ2,6-R2)}2]
with RꢁCl (4a) or H (4b). The yield of 5b was
D,
L
-) of the bis(cyclopalladated)
C(Me)ꢀNꢀNꢀC(H)-
Cl (5a) or H
/
/
/
/
/
/
/
Cipso bond of the other half of the molecule is not
hindered.
/
Finally, since it is well known that some cyclopalla-
dated derivatives are useful precursors for the synthesis
of organic or organometallic derivatives [3], the two
isomeric forms of compounds 5 presented in this work
have an additional interest since they appear to be
excellent candidates to undertake further studies focused
/
/
/
/
/
/
significantly smaller than that of 5a and unreacted
ligand 4b was also recovered from the crude of the
reaction. Thus, the comparison of these findings sug-
gests that tiny changes in the nature of the aryl ring
bound to the nitrogen are important to determine the
ease with which these substrates undergo the double
cyclopalladation. Although ligand 4a contains a bulkier
aryl group than 4b [18], it is more prone to undergo the
bis(metallation) process.
on the reactivity of the s(Pdꢀ
/
C) bonds versus small
molecules such as alkynes, alkenes or CO, which may
allow the preparation of novel tetrasubstituted ferroce-
nyl derivatives with planar chirality.
3. Experimental
On the other side, since the formation of the
bis(cyclopalladated) complexes 5 requires longer reac-
tion periods (6 days) than those derived from the
3.1. Materials and synthesis
bis(ferrocenylimines) of the type: [Fe{(h5-C5H4)ꢀ
/
/
All the reagents used for the preparations described in
this work were obtained from Aldrich, except for
compound: [Fe{(h5-C5H4)ꢀ
C(R)ꢀ
/
Nꢀ
/
R?}2] {with Rꢁ
/
H, R?ꢁ
/
CH2C6H5 (2), Rꢁ
4-Me (3b) (Fig. 1) (2
Me, R?ꢁ
/
C6H5 (3a) or C6H4ꢀ
/
/
C(Me)ꢀ
/
NꢀNH2}] which
/
days) [6] we can conclude that in this type of processes
ligands 4 are less reactive than compounds 2 and 3.
was prepared as described previously [7], and the
solvents were distilled and dried according to the
standard procedures [21] before their use.
Elemental analyses (C, H and N) were carried out at
the Serveis Cientifico-Te`cnics (Universitat de Barcelona)
or at the Institut de Qu´ımica Bio-Orga`nica (C.S.I.C.,
Barcelona). Infrared spectra were recorded with a
Nicolet-Impact 400 instrument using KBr pellets. Rou-
tine 1H- and 13C{1H}-NMR spectra were obtained with
a Gemini-200 MHz instrument using CDCl3 as solvent
The relative abundance of the meso- and
5a and 5b [meso- and molar ratiosꢁ
and 1.10 (for 5b)] was very similar and the interconver-
sion of the two stereoisomers meso- form l - would
C)bond. Since it is well
D,
L
forms of
D,
L
/1.02 (for 5a)
/D,L
require the cleavage of the s(Pdꢀ
/
known that the reaction of the di-m-chloro-bridged-
cyclopalladated complexes with Lewis bases, such as
PPh3, does not involve the cleavage of the s(Pdꢀ
/
C) or
1
s(PdꢀN) bond, the relative ratio of the two stereo-
/
and SiMe4 as internal reference. High resolution H-
NMR spectra and the two dimensional {1Hꢀ13
C}-NMR
isomers of 5 should be predetermined in the cyclome-
tallation process which takes place before the addition
of the triphenylphosphine.
It is widely accepted that the cyclopalladation of N-
donor ligands proceeds in two steps: the binding of the
palladium and the subsequent electrophilic attack [19].
On this basis, the formation of nearly equimolar
/
experiments {heteronuclear single quantum coherence
(HSQC) and heteronuclear multiple bond coherence
(HMBC)} were carried using either a Varian 500 or a
Bruker 500 instrument, and the same solvents as
mentioned above for the monodimensional experiments.
31P{1H}-NMR spectra of 5 were recorded with a
Bruker-250 DXR instrument using CDCl3 as solvent
amounts of the two isomeric forms [meso-/
D,L- form
molar ratioꢁ1.02 (for 5a) and 1.10 (for 5b)], can be
/
and P(OMe)3 as reference [d 31P{P(OMe)3}ꢁ
/140.17
rationalised using a similar argument as reported for the
double cycloplatination of the 1,1?-bis(ferrocenylamine)
ppm] and the two-dimensional {1Hꢀ31
/
P}-NMR spectra
were recorded with a Bruker Avance 600 MHz instru-
ment. In all cases the chemical shifts (d) are given in
ppm, the coupling constants (J) in Hz and the labelling
[Fe{(h5-C5H4)ꢀ
tallacycle is formed, the remaining C5H5 moiety may
/
CH2ꢀ
/
NMe2}2] [20]. Once the first me-

40
C. Lo´pez et al. / Journal of Organometallic Chemistry 672 (2003) 34ꢀ42
/
scheme used for the assignment of the signals corre-
sponds to that shown in Scheme 1.
CH2Cl2. The yellow needles of trans-[PdCl2(PPh3)2]
formed were removed from the solution by filtration
and the evaporation of the filtrate produced 5a (yield:
245 mg, 53%). The separation of the two isomers was
3.1.1. Preparation of [Fe{(h5-C5H4)ꢀ
C(H)(2,6-Cl2ꢀC6H3)}2] (4a)
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
/
carried out as follows: 5a (200 mg, 1.4ꢄ
dissolved in 5 ml of CH2Cl2 and the resulting solution
was passed by a short (6 cmꢄ2 cm) SiO2-column
chromatography. The elution with a CH2Cl2ꢀMeOH
/
10ꢂ4 mol) were
A suspension formed by [Fe{(h5-C5H4)ꢀ
/
C(Me)ꢀ
/
Nꢀ
/
NH2}2] (250 g, 1.03ꢄ
/
10ꢂ3 mol), 2,6-dichlorobenzalde-
10ꢂ3 mol) and 30 ml of ethanol
/
hyde (300 mg, 2.05ꢄ
/
/
was refluxed for 3 h. After this period the hot and red
solution was filtered out. The filtrate was allowed to
cool down to room temperature (r.t.) on an open vessel.
The red crystals formed were collected, air-dried and
then dried in vacuum for 1 day (yield: 0.413 g, 65.5%).
Characterisation data for 4a: Anal. Calc. for:
C28H22Cl4N4Fe (Found): C, 54.94 (54.87); H, 3.62
(100/0.1) solution produced the release of a deep- red
band which gave after concentration to dryness to the
meso- form of 5a (98 mg). Once this band was collected
a mixture of CH2Cl2ꢀ
eluant and a deep purple band was collected. The
/
MeOH (100/0.1) was used as
D,L-
form of 5a was isolated from this solution by concen-
tration to dryness on a rotary evaporator (81 mg).
Characterisation data for 5a: Anal Calc. for
C64H50N4Cl6FeP2Pd2 (Found): C, 54.19 (54.1); H, 3.55
(3.65) and N, 9.15 (9.12)%. IR: 1613 cmꢂ1, n(ꢀ
/
Cꢀ
). H-NMR data: 2.39 [s, 6H, Me], 4.83 [t, 4H, H2
and H5], 4.47 [t, 4H, H3 and H4], 8.60 [s, 2H, ꢀ
CHꢀNꢀ],
7.31 [d, 2H, H3?], 7.15 [t, 2H, H4?] and 7.31 [d, 2H, H5?].
13C{1H}-NMR data: 16.69 (Me), 152.4 (ÈCꢀ
Nꢀ), 82.5
(C1), 71.86 (C2 and C5), 69.28 (C3 and C5), 167.2 (ꢀ
CHꢀ
Nꢀ
), 135.33 (C2? and C6?), 128.80 (C3? and C5?) and 130.0
(C4?).
/
1
Nꢀ
/
/
/
/
(3.6) and N, 3.95 (3.90)%. IR: n(ÈCꢀ
/
Nꢀ
/
)ꢁ1610 and
/
1596 cmꢂ1. Meso- form: H-NMR data (in ppm): 2.18
1
/
/
[s, 6H, Me], 3.20 [t, 2H, H3], 4.10 [t, 2H, H4], 4.60 [t, 2H,
/
/
H5], 9.20 [d, 2H, ꢀ
/
CHꢀ
H4? H5? and aromatic protons of PPh3]; 31P{1H}-NMR
data (in ppm): 37.6.
- form: 1H-NMR data (in ppm):
2.41 [s, 6H, Me], 2.98 [t, 2H, H3], 3.05 [t, 2H, H4], 4.79 [t,
2H, H5], 9.60 [d, 2H, ꢀ ], 7.18 [t, 2H, H4?] and
CHꢀNꢀ
7.30ꢀ
7.80 [m, 34H, H3?, H5? and aromatic protons of
PPh3]; 31P{1H}-NMR data (in ppm): 38.7.
/
Nꢀ
/
] and 7.3ꢀ
/
7.90 [m, 36H, H3?,
/
D,L
3.1.2. Preparation of [Fe{(h5-C5H4)ꢀ
C(H)(C6H5)}2] (4b)
This compound was prepared using the same proce-
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
/
/
/
/
dure as described above for 4a, but using [Fe{(h5-
C5H4)ꢀ
/
C(Me)ꢀ
/
Nꢀ
/
NH2}2] (800 mg, 2.7ꢄ
/
10ꢂ3 mol)
3.1.4. Preparation of [Pd2{Fe[(h5-C5H3)ꢀ
NꢀC(H)(C6H5)]2}Cl2(PPh3)2] (5b)
This compound was prepared using the procedure
described above for [Pd2{Fe[(h5-C5H3)ꢀ
C(Me)ꢀNꢀNꢀ
C(H)(C6H3ꢀ2,6-Cl2)]2}Cl2(PPh3)2], but using ligand 4a
(400 mg, 8ꢄ
10ꢂ4 mol), Na2[PdCl4] (470 mg, 1.6ꢄ
/
C(Me)ꢀ
/
Nꢀ
/
and benzaldehyde (600 mg, 5.7ꢄ
/
10ꢂ3 mol). (Yield:
850 mg, 66.8%). Characterisation data for 4b: Anal.
/
Calc. for C28H26FeN4 (Found): C, 70.89 (70.6); H, 5.52
/
/
/
/
(5.6) and N, 11.81 (11.7)%. IR: n(ꢀ
/
Cꢀ
cmꢂ1. H-NMR data: 2.39 [s, 6H, Me], 4.80 [t, 4H, H2
and H5], 4.45 [t, 4H, H3 and H4], 8.38 [s, 2H, ꢀ
CHꢀNꢀ],
7.64 [d, 4H, H2?, H6?] and 7.28 [m, 6H, H3?, H4? and, H5?].
13C{1H}-NMR data: 16.1 (Me), 158.4 (ÈCꢀ
Nꢀ), 83.9
(C1), 71.7 (C2 and C5), 68.9 (C3 and C5), 166.5 (ꢀ
CHꢀ
Nꢀ
), 128.5 (C2?), 130.3 (C3? and C5?), 134.2 (C4?) and
130.3 (C6?).
/
Nꢀ
/
)ꢁ
/
1611
/
1
/
/
/
/
/
10ꢂ4 mol) and Na(CH3COO)×
/
3H2O (217 mg, 1.6ꢄ
/
10ꢂ4 mol) as starting material. Since the crude of the
reaction was a mixture of several compounds, it was
dissolved in CH2Cl2 and passed through a short SiO2-
/
/
/
/
/
column chromatography (20 cmꢄ2 cm). Elution with
/
CH2Cl2 produced the release of two bands. The pale
yellow band lead by concentration cis-[PdCl2(PPh3)2]
and the second and red band gave unreacted ligand 4b.
3.1.3. Preparation of [Pd2{Fe[(h5-C5H3)ꢀ
NꢀC(H)(C6H3ꢀ2,6-Cl2ꢀ)]2}Cl2(PPh3)2] (5a)
A mixture containing ligand 4a (200 mg, 3.26ꢄ
mol), Na2[PdCl4] (191 mg, 6.5ꢄ
10ꢂ4mol) and
Na(CH3COO)×3H2O (88 mg, 6.5ꢄ
10ꢂ4 mol) and 60
/
C(Me)ꢀ
/
Nꢀ
/
/
/
/
Once these bands were collected, the use of a
/
10ꢂ4
CH2Cl2:MeOH (100:0.1) mixture as eluant produced
the release of a deep-red band which gave, after
concentration, 5b. Characterisation data for 5b: Anal.
Calc. for C64H54N4Cl3FeP2Pd2 (Found): C, 60.02 (59.8);
/
/
/
ml of methanol was protected from the light with
aluminium foil and stirred at r.t. for 6 days. After this
period the solid formed was collected by filtration and
washed with three (5 ml) portion of methanol. The deep
purple solid was then dissolved in 50 ml of CH2Cl2 and
H, 4.25 (4.2) and N, 4.37 (4.3)%. IR: n(ÈCꢀ
/
Nꢀ
/
)ꢁ
/
1610 and 1592 cmꢂ1. The meso- and the
D,L
- forms
were separated from the crude 5b (0.382 mg) using the
same procedure as described in the previous section.
treated with 170 mg (6.5ꢄ
/
10ꢂ4 mol) of PPh3 and
(meso- form: 90 mg;
NMR data (in ppm): 1.98 [s, 6H, Me], 3.18 [t, 2H, H3],
3.92 [t, 2H, H4], 4.18 [t, 2H, H5], 8.42[d, 2H, ꢀ
CHꢀNꢀ],
and 7.29ꢀ7.90 [m, 40 H, aromatic protons of the C6H5
rings of the ligand and of the PPh3 groups]; 31P{1H}-
D,L
- form: 81 mg). Meso- form: 1H-
stirred at r.t. for 2 h. The undissolved material were
removed by filtration and concentrated to ca. 10 ml then
n-hexane was added. The solid formed was collected by
filtration and then dissolved in the minimum amount of
/
/
/
/

C. Lo´pez et al. / Journal of Organometallic Chemistry 672 (2003) 34ꢀ
/42
41
NMR data (in ppm): 36.03.
ppm): 2.42 [s, 6H, Me], 2.95 [t, 2H, H3], 3.06 [t, 2H, H4],
4.40 [t, 2H, H5], 9.02 [d, 2H, ꢀ
CHꢀNꢀ] and 7.30ꢀ7.80
[m, 40H, aromatic protons of the C6H5 rings of the
ligand; of the PPh3 groups] and 31P{1H}-NMR data (in
ppm): 37.63.
D
,
L
- form:1H-NMR data (in
hydrogen atoms were located from a difference synthesis
and refined with an overall isotropic temperature factor.
/
/
/
/
The final R (on F) factor was 0.044, wR (on F)ꢁ0.103.
/
Further details concerning the resolution and refinement
of the crystal structure of 4a are presented in Table 2.
4. Supplementary material
3.2. Crystal structure determination
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 199101 for 4a. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2 1EZ,
A prismatic crystal of 4a (0.1 mmꢄ
/
0.1 mmꢄ0.2
/
mm) was selected and mounted on a MAR345 diffract-
ometer with a image plate detector. Unit cell parameters
(Table 2) were determined from automatic centring of
7548 reflections in the range 35
least-squares method. Intensities were collected with
graphite monochromatized MoꢀKa radiation. The
number of reflections measured in the range 2.085
U 528.848 was 10308, of which 3452 were non-equiva-
lent by symmetry Rint (on I)ꢁ0.030; 2943 reflections
were assumed as observed applying the condition Iꢀ
/
U 5
/
318 and refined by
UK (Fax: ꢃ44-1223-336033; e-mail: deposit@ccdc.
/
cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
/
/
/
Acknowledgements
/
/
We are grateful to the Ministerio de Ciencia y
Tecnologia of Spain and to the Generalitat de Catalu-
nya (grants: BQU2000-0654 and 2001SGC-00054, re-
spectively) for financial support.
2s(I). Lorentz-polarisation corrections were made but
absorption corrections were not.
The structure was solved by Direct methods using
SHELXS computer program [22] and refined by the least-
squares method with the SHELX-97 computer program
[23] using 3452 reflections (very negative intensities were
2
References
not assumed). The function minimized was S wjjFoj ꢂ
/
2 2
jFcj j where wꢁ
/
[s2(I)ꢃ
/
(0.0433P)2ꢃ4.4914P]ꢂ1, and
/
2
2
[1] (a) G.R. Newkome, W.E. Puckett, W.K. Gupta, G.E. Kiefer,
Chem. Rev. 86 (1986) 451;
Pꢁ
/
(jFoj ꢃ2jFcj )/3. f, f? and fƒ were taken from
/
International tables of X-ray crystallography [24]. All
(b) V.V. Dunina, O.A. Zalevskaya, V.M. Potatov, Russ. Chem.
Rev. 57 (1988) 250;
Table 2
Crystal data and details of the refinement of the crystal structure of
(c) A.D. Ryabov, Chem. Rev. 90 (1990) 403;
(d) I. Omae, Coord. Chem. Rev. 83 (1988) 137.
[2] (a) I. Omae, Applications of Organometallic Compounds, Ch. 20,
Wiley, Chichester, 1998;
compound
(4a)
[Fe{(h5-C5H4)ꢀ
/
C(Me)ꢀ
/
Nꢀ
/
Nꢀ
/
C(H)(2,6-Cl2 ꢀC6H3)}2]
/
(b) A.J. Klaus, Modern Colorants: Synthesis and Structure, vol. 3,
London, 1995, p. 1.;
Empirical formula
Mw
C28H22Cl4FeN4
612.15
(c) M. Ghedini, A. Crispini, Comm. Inorg. Chem. 21 (1999) 53
(and references therein);
Crystal system
Space group
Unit cell dimensions
Monoclinic
C2/c
(d) P. Espinet, M.A. Esteruelas, L.A. Oro, J.L. Serrano, E. Sola,
Coord. Chem. Rev. 117 (1992) 215;
˚
a (A)
16.680(1)
14.690(1)
13.5738(7)
90
(e) B.S. Wild, Coord. Chem. Rev. 166 (1997) 291 (and references
therein);
˚
b (A)
˚
c (A)
(f) F. Neve, A. Crispini, C. Di Pietro, S. Campagna, Organome-
tallics 21 (2002) 3511 (and references therein);
(g) A.S. Gruber, D. Zim, G. Ebeling, A.L. Monteiro, J. Dupont,
Organic. Lett. 2 (2000) 1287 (and references therein);
(h) C. Lo´pez, R. Bosque, D. Sainz, X. Solans, M. Font-Bard´ıa,
Organometallics 16 (1997) 3261;
a (8)
b (8)
g (8)
127.844(5)
90
3
˚
V (A )
2626.5(3)
4
1.548
Z
Dcalc (Mg mꢂ3
)
(i) M. Torres-Lo´pez, A. Ferna´ndez, J.J. Ferna´ndez, A. Sua´rez, S.
Castro-Ju´ız, J.M. Vila, M.T. Pereira, Organometallics 20 (2001)
1350.
Absorption coefficient (mmꢂ1
)
1.008
U Range for data collection (8)
No. of reflections collected
2.08ꢀ
/
28.84
10308
[3] (a) J. Spencer, M. Pfeffer, Adv. Met.-Org. Chem. 6 (1998) 103
(and references therein);
No. of unique reflections [Rint
No. of data
No. of parameters
Goodness-of-fit on F2
]
0.0302
3452
212
(b) M. Pfeffer, Recl. Trav. Chim. Pays-Bas 109 (1990) 567 (and
references therein);
1.121
(c) A.D. Ryabov, Synthesis (1985) 233 and references therein.
[4] (a) S. Trofimenko, Inorg. Chem. 12 (1973) 1215;
(b) I.G. Phillips, P.J. Steel, J. Organomet. Chem. 410 (1991) 247;
(c) C.B. Cargill, R.M. Marthson, P.J. Steel, J. Organomet. Chem.
Final R indices [I ꢀ
R indices (all data)
/
2s(I)]
R1ꢁ/0.0440, wR2ꢁ
/
0.1030
R1ꢁ/0.0531, wR2ꢁ
/0.1162

42
C. Lo´pez et al. / Journal of Organometallic Chemistry 672 (2003) 34ꢀ42
/
382 (1996) 455;
Colorants: Synthesis and Structure, vol. 3, Academic and Profes-
sional, London, UK, 1995.
(d) P.J. Steel, G.B. Caygill, J. Organomet. Chem. 395 (1990) 359;
(e) R.M. Ceder, J. Sales, J. Organomet. Chem. 294 (1985) 389;
(f) R.M. Ceder, J. Granell, J. Sales, J. Organomet. Chem. 307
(1986) C44;
[13] T.H. Allen, O. Kennard, Chem. Des. Autom. News 8 (1993) 146.
[14] (a) C. Lo´pez, J. Sales, R. Zquiak, J. Chem. Soc. Dalton Trans.
(1992) 2321.;
(b) R. Bosque, C. Lo´pez, J. Sales, X. Solans, J. Organomet. Chem.
483 (1994) 61.
(g) A.R. Siedle, J. Organomet. Chem. 208 (1981) 115;
(h) M. Lo´pez-Torres, J. Juanatey, J.J. Ferna´ndez, A. Ferna´ndez,
A. Sua´rez, R. Mosteiro, J.M. Ortigueira, J.M. Vila, Organome-
tallics 21 (2002) 3628.
[15] Y. Wu, S. Huo, J. Gong, X. Cui, L. Ding, K. Ding, C. Du, Y. Liu,
M. Song, J. Organomet. Chem. 637-639 (2001) 27.
[16] J.G. Verkade, L.D. Quin (Eds.), Phosphorous-31-NMR Spectro-
scopy in Stereochemical Analysis of Organic Compounds and
Metal Complexes, VCH, Deerfield, Ireland, 1987.
[17] (a) J. Vicente, A. Arcas, D. Bautista, P.G. Jones, Organometallics
16 (1997) 2129;
[5] M. Sugimoto, M. Nonoyama, Inorg. Nucl. Chem. Lett. 15 (1979)
405.
[6] (a) R. Bosque, C. Lo´pez, X. Solans, M. Font-Bard´ıa, Organo-
metallics 18 (1999) 1267;
(b) Y.J. Wu, Y.H. Liu, L. Yang, Q.X. Zhu, Polyhedron 16 (1997)
335.
(b) J. Vicente, J.A. Abad, A. Frankland, C. Ramirez de Arellano,
Chem. Eur. J. 5 (1995) 3066.
[7] F. Chen-jie, D. Chung-ying, M. Hong, H. Cheng, M. Qing-jin, L.
Yong-jiang, M. Yu-hua, Organometallics 20 (2001) 2525.
[8] (a) R. Bosque, C. Lo´pez, J. Sales, J. Organomet. Chem. 498 (1995)
147;
[18] C. Hansch, A. Leo, D. Koekman, Exploring QSAR, Hydro-
phobic, Electronic and Steric Constants, ACS, Prof. Ref. Books,
Washington, DC, 1995.
[19] (a) A.D. Ryabov, I.K. Sakodinskaya, A.K. Yatsimirski, J. Chem.
Soc. Dalton Trans. (1985) 2629.;
(b) R. Bosque, C. Lo´pez, J. Sales, D. Tramuns, X. Solans, J.
Chem. Soc. Dalton Trans. (1995) 1839.;
(b) A.D. Ryabov, A.K. Yatsimirski, Inorg. Chem. 23 (1984) 798;
(c) A.D. Ryabov, Inorg. Chem. 26 (1987) 1292;
(d) M. Go´mez, J. Granell, M. Martinez, Organometallics 16
(1997) 2539;
(c) C. Lo´pez, R. Bosque, M. Font-Bard´ıa, X. Solans, J. Silver, G.
Fern, J. Chem. Soc. Dalton Trans. (1995) 4053.
[9] R. Bosque, C. Lo´pez, J. Sales, X. Solans, M. Font-Bard´ıa, J.
Chem. Soc. Dalton Trans. (1994) 735.
(e) M. Go´mez, J. Granell, M. Martinez, J. Chem. Soc. Dalton
Trans. (1988) 37.
[10] The least-squares equation of the plane defined by the set of
atoms: C(1), C(2), C(3), C(4) and C(5) is (0.9867)XOꢃ
(0.0175)YOꢃ(0.1615)ZOꢁ2.1643. Maxima deviations were
found for C(3), 0.003 and C(4), ꢂ
[11] The least-squares equation of the plane defined by the sets of
atoms [C(1)ꢀC(5)], [C(6), N(1), N(2), C(8)] and [C(9)ꢀC(14)] is
(0.9872)XOꢃ(ꢂ0.0129)YOꢃ(0.1587)ZOꢁ2.2105. Deviations
from the plane: N(1), 0.038; N(2), ꢂ0.001; C(1), ꢂ0.002; C(2),
0.025; C(3), 0.004; C(4) 0.005; C(5), ꢂ0.026; C(6), ꢂ0.090; C(8),
0.005; C(9)ꢂ0.009; C(10), ꢂ0.016; C(11), ꢂ0.005; C(12), 0.010,
/
[20] P.R.R. Ranatunge-Bandarage, B.H. Robinson, J. Simpson,
Organometallics 13 (1994) 511.
/
/
˚
0.003 A.
/
[21] D.D. Perrin, W.F.L. Armarego, Purification of Laboratory
Chemicals, 4th ed., Butterworth-Heinemann, Bath, UK, 1996.
[22] G.M. Sheldrick, SHELXS, A Computer Program for Determina-
/
/
/
/
/
/
tion of Crystal Structures, University of Gottingen, Germany,
¨
/
/
1997.
[23] G.M. Sheldrick, SHELX-97, A Computer Program for Determina-
tion of Crystal Structures, University of Gottingen, Germany,
¨
/
/
ꢂ/
/
/
/
˚
C(13), 0.026 and C(14), 0.017 A
[12] (a) A. Bondi, J. Phys. Chem. 68 (1964) 441;
1997.
[24] International Tables of X-ray Crystallography, vol. IV, Kynoch
Press, Birmingham, UK, 1974, pp. 99, 100 and 1049.
(b) A.K. Klaus, in A.E. Peters, H.S. Freemann (eds). Modern