Further iminopyrrolyl complexes of nickel, cobalt, iron and copper: Synthesis and structural characterisation

Article abstract of DOI:10.1016/j.jorganchem.2013.10.053

The reaction between two equivalents of 2-(N-arylformimino)pyrrolyl sodium salts (NaNC₄H₃C(H) = N-Ar), with Ar = C₆H ₅ (I), 2,6-iPr₂-C₆H₃ (II) or 2-(N-arylformimino)phenanthro[9,10-c]pyrrolyl sodium salts (NaNC ₁₆H₁₀C(H)N-Ar), with ArC₆H₅ (III), 2,6-iPr₂-C₆H₃ (IV) and one equivalent of nickel(II), cobalt(II), iron(II) and copper(I) halides, in THF, at low temperatures, afforded bis(iminopyrrolyl) or bis(iminophenanthro[9,10-c] pyrrolyl) complexes with different geometries around the metal centres. Nickel(II) derivatives displayed distorted square planar geometries, whereas for cobalt a tetrahedral complex is proposed. The reactions with FeCl₂ resulted in very unstable products, giving rise to dimers with pentacoordinated Fe(III) centres. The addition of two equivalents of pyridine to the reaction medium improved the stability of the resulting compound, enabling the formation of a 16-electron Fe(II) complex, which contained simultaneously two iminopyrrolyls and also a pyridine ligand. In the reaction of CuBr with 2-(N-2,6-diisopropylphenylformimino)pyrrolyl sodium salt, a complex with the general formulation [Cu(iminopyrrolyl)]_x was obtained. When exposed to the air, this complex gives rise to the corresponding bis(iminopyrrolyl) Cu(II) complex.

Full text of DOI:10.1016/j.jorganchem.2013.10.053

Journal of Organometallic Chemistry 760 (2014) 167e176
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Further iminopyrrolyl complexes of nickel, cobalt, iron and copper:
Synthesis and structural characterisationq
*
Clara S.B. Gomes, M. Teresa Duarte, Pedro T. Gomes
Centro de Química Estrutural, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa,
Portugal
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction between two equivalents of 2-(N-arylformimino)pyrrolyl sodium salts (NaNC4H3C(H) ¼ N-
Ar), with Ar ¼ C6H5 (I), 2,6-iPr2-C6H3 (II) or 2-(N-arylformimino)phenanthro[9,10-c]pyrrolyl sodium salts
(NaNC16H10C(H)]N-Ar), with Ar]C6H5 (III), 2,6-iPr2-C6H3 (IV) and one equivalent of nickel(II), cobalt(II),
iron(II) and copper(I) halides, in THF, at low temperatures, afforded bis(iminopyrrolyl) or bis(imino-
phenanthro[9,10-c]pyrrolyl) complexes with different geometries around the metal centres. Nickel(II)
derivatives displayed distorted square planar geometries, whereas for cobalt a tetrahedral complex is
proposed. The reactions with FeCl2 resulted in very unstable products, giving rise to dimers with pen-
tacoordinated Fe(III) centres. The addition of two equivalents of pyridine to the reaction medium
improved the stability of the resulting compound, enabling the formation of a 16-electron Fe(II) complex,
which contained simultaneously two iminopyrrolyls and also a pyridine ligand. In the reaction of CuBr
with 2-(N-2,6-diisopropylphenylformimino)pyrrolyl sodium salt, a complex with the general formulation
[Cu(iminopyrrolyl)]x was obtained. When exposed to the air, this complex gives rise to the corresponding
bis(iminopyrrolyl) Cu(II) complex.
Received 8 October 2013
Received in revised form
27 October 2013
Accepted 29 October 2013
Keywords:
Cobalt
Copper
Iminopyrrolyl ligands
Iron
Nickel
X-ray diffraction
Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
their complexes, being versatile spectator ligands in catalytic
species, namely in post-metallocene catalysts for olefin polymer-
Monoanionic bidentate nitrogen ligands are of particular in-
terest in the stabilisation of a vast number of metal complexes.
Among such type of ligands is the 2-iminopyrrolyl bidentate
chelating ligand, containing an anionic pyrrolyl ring substituted in
position 2 by a neutral imine donor moiety, which may be
considered structurally similar to salicylaldiminate, anilidoimine
or 2-(2-pyridyl)indolyl ligands. The 2-iminopyrrolyls are
appealing ligands because they are readily accessible and easy to
modify, either sterically or electronically, via straightforward
Schiff-base condensation procedures [1]. The first examples of
homoleptic 2-iminopyrrolyl metal complexes of Co(II), Ni(II),
Pd(II), Cu(II) and Zn(II) have been described in the 1960s [2].
However, only recently this class of ligands has been commonly
employed in the synthesis of several transition-metal compounds
[3]. Another important feature is that they provide high stability to
isation [3,4].
Our group has been interested in the synthesis and structural
characterisation of a series of Na [5], Co(II) [6], Co(III) [7], Ni(II) [8],
Zn(II) [9], and B(III) [10] complexes containing 2-(N-arylimino)
pyrrolyl ligands or 2-(N-arylimino)phenanthro[9,10-c]pyrrolyl li-
gands (Chart 1). The bis-chelate Zn(II) and B(III) complexes showed
tetrahedral geometries around the metal centres (Chart 1, DeF),
some of the species exhibiting interesting luminescent properties
[9,10]. In the case of Co(II) bis-chelate derivatives, the geometry
around the metal centre was dependent upon the bulkiness of the
substituents at the iminopyrrolyl ligand. Only the Co(II) derivative
bearing the bulkiest 2-iminopyrrolyl ligand (Chart 1, B) showed a
square-planar geometry, the remaining complexes being tetrahe-
dral (Chart 1, A) [6a]. Attempts to obtain Co(II) tris-chelate de-
rivatives were unfruitful, except for the less sterically demanding 2-
(N-phenylformimino)pyrrolyl-type ligands, their formation occur-
ring though with the concomitant oxidation of Co(II) to Co(III)
(Chart 1, C). The B(III) and Zn(II) compounds were prepared by
acidebase reaction between the parent neutral iminopyrrole pre-
cursors and aryl or alkyl derivatives of boron and zinc. The latter
homoleptic bis(2-(N-arylformimino)pyrrolyl) complexes of Zn(II)
q
Dedicated to Professor Maria José Calhorda on the occasion of her 65th
birthday.
* Corresponding author. Tel./fax: þ351 218419612.
E-mail address: pedro.t.gomes@ist.utl.pt (P.T. Gomes).
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.10.053

168
C.S.B. Gomes et al. / Journal of Organometallic Chemistry 760 (2014) 167e176
Chart 1. Examples of other 2-(N-arylformimino)pyrrolyl complexes synthesised by the authors.
were obtained alternatively by reaction of the corresponding metal
dichloride with two equivalents of the corresponding 2-(N-aryli-
mino)pyrrolyl sodium salt or of its fused derivatives, this method
being also employed for the synthesis of Co(II) and Co(III) homo-
leptic compounds.
NMR spectroscopy, Mass Spectrometry and, whenever possible,
X-ray Diffraction.
2. Results and discussion
In the present paper, in order to extend the scope of bis(imi-
nopyrrolyl) and bis(iminophenanthro[9,10-c]pyrrolyl) complexes
to transition-metals such as nickel, cobalt, iron and copper, we
report the preparation of a series of new bis(2-(N-arylformimino)
pyrrolyl) and bis(2-(N-arylformimino)phenanthro[9,10-c]pyrrolyl)
chelates of the above mentioned metals and its characterisation by
2.1. Synthesis of metal complexes
The four ligand precursors derived from 2-arylformimino
pyrrole (IeIV) used in this work (Scheme 1) were prepared by
condensation of 2-formylpyrrole or 2-formylphenanthro[9,10-c]

C.S.B. Gomes et al. / Journal of Organometallic Chemistry 760 (2014) 167e176
169
Scheme 1. Synthesis of complexes 5e9.
pyrrole with aniline or 2,6-diisopropylaniline, employing standard
conditions, according to the method described previously [5e10].
In previous publications [6,9], metal halides were used as
starting materials for the synthesis of homoleptic bis(imino-
pyrrolyl) Zn(II) and Co(II) complexes. Therefore, in a first approach,
anhydrous NiBr2 was employed as starting material in the prepa-
ration of Ni(II) derivatives. The synthetic procedure consisted in the
treatment of ligand precursors IeIV with one equivalent of sodium
hydride in THF, at ꢀ20 ꢁC, which resulted in the deprotonation of
the pyrrole NH proton, giving rise to the in situ formation of the 2-
(N-arylformimino)pyrrolyl or 2-(N-arylformimino)phenanthro
[9,10-c]pyrrolyl sodium salts 1e4 (Scheme 1). The addition of
compound 1 to a suspension of NiBr2 in THF, at ꢀ80 ꢁC, followed by
warming up and stirring overnight, at room temperature, afforded
red crystals of Ni(II) complex 5 (Scheme 1), although in a low yield
(15%). These crystals were suitable enough for X-ray diffraction (see
below, Section 2.2). However, for ligand precursors IIeIV, the re-
action was not successful, being possible to recover a significant
amount of reprotonated ligand. As a result, we decided to investi-
gate an alternative procedure that could enable the preparation of
the remaining Ni(II) complexes. Bochmann et al. [11] had already
reported the synthesis of bis(aryliminopyrrolyl)nickel complex
(aryl ¼ 2,6-iPr2C6H3) 6 (Scheme 1), in 15% yield from the reaction of
the corresponding iminopyrrolyl lithium salt with [NiBr2(DME)]
(DME ¼ 1, 2-dimethoxyethane), in Et2O. Nevertheless, we decided
to carry out the preparation of this compound using our synthetic
methodology described above. The reaction of sodium salt 2 with
[NiBr2(DME)] in THF, led to complex 6 in 80% yield (Scheme 1). This
significant increase in the reaction yield, when compared with that
reported by Bochmann et al. [11], can be attributed to the higher
solubility of the reagents in THF than in Et2O. In fact, Flores et al.
[12] have also prepared complex 6 in a very high yield (92%), using a
procedure very similar to ours, but employing acetonitrile as the
reaction solvent.
instability of the iminopyrrolyl and iminophenanthro[9,10-c]pyr-
rolyl ligands, which are prone to reprotonation of the pyrrolyl
moiety [13].
As referred above, our group reported recently the syntheses
and characterisation of a series of cobalt complexes containing
bis(iminopyrrolyl) ligands, which were prepared in high yields [6a].
In the light of these results, we have investigated the preparation of
Co(II) complexes bearing the new 2-(N-arylformimino)phenanthro
[9,10-c]pyrrolyl ligands. Ligand precursor IV, containing a 2,6-
diisopropylphenyl group as the N-aryl substituent of the iminic
moiety, was reacted with one equivalent of sodium hydride, in THF.
The resulting sodium salt 4 was then slowly added to CoCl2 in the
same solvent, affording the paramagnetic Co(II) complex 9, in 91%
yield, as a brown-reddish solid. Several recrystallisations were
tried, but it was impossible to obtain crystals suitable for X-ray
diffraction. Despite the paramagnetic nature of this complex, its 1H
NMR spectrum was recorded in CD2Cl2, showing sharp resonances
between ca. 20 and ꢀ26 ppm. The work developed in our group
concerning the synthesis of a series of four-coordinate Co(II)
complexes showed that all, except one, exhibited tetrahedral ge-
ometries; the most hindered derivative (bis(2-(N-2,6-diisopropyl
phenylacetimino)pyrrolyl)cobalt(II)) displaying a square planar
geometry [6a]. Taking these facts into account, a tetrahedral ge-
ometry is proposed for the present formiminophenanthro[9,10-c]
pyrrolyl derivative 9. However, when ligand precursor III was
employed under the same reaction conditions, a diamagnetic
octahedral
tris(2-(N-phenylformimino)phenanthro[9,10-c]pyr-
rolyl)cobalt(III) complex was obtained, in 58% yield [7].
We have also evaluated the use of FeCl2 to prepare bis(imino-
pyrrolyl) complexes. We have attempted the preparation of
homoleptic iron complexes using “simple” iminopyrrolyl ligand
precursors I and II, under the same reaction conditions as those
employed above for Zn, Ni and Co. The reaction products were
extracted with Et2O and n-hexane, for ligand precursors I and II,
respectively. However, these products were highly thermally un-
stable, their crystals decomposing easily into brownish powders.
Nevertheless, it was still possible to isolate from the mixtures very
few crystals of both reactions. The structures of the Fe(III) com-
plexes 10 and 11, were determined by X-ray diffraction (Section
The use of the 2-(N-arylformimino)phenanthro[9,10-c]pyrrole
ligand precursors III and IV, in the same reaction conditions, gave
rise to complexes 7 and 8 as bronze crystals and a dark brown solid,
in 74 and 37% yield, respectively. The discrepancy in the yields
obtained for this type of complexes can be attributed to the

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C.S.B. Gomes et al. / Journal of Organometallic Chemistry 760 (2014) 167e176
2.2), and are represented in Fig. 1 (a) and (b), respectively. Both
compounds are dimers containing bis(iminopyrrolyl)iron moieties
introduced by the coordination of Py, compound 12, a 16-electron
species, is still thermally sensitive. Therefore, in an attempt to
obtain the corresponding octahedral Fe(II) complex containing
two iminopyrrolyl ligands and two coordinated Py molecules, we
decided to repeat this synthesis now increasing the amount of Py
from 2 to 12 equivalents. However, this procedure only gave rise
to the same reaction product, complex 12, although in higher
yields (64%).
and bridging oxygen atoms but, while in compound 10 the
ligand is bonded to two bridging Na atoms, which are each of them
further bonded to an Et2O molecule, in 11 only a single -oxo ligand
is connecting the two bis(iminopyrrolyl)iron moieties. The forma-
tion of these Fe(III) complexes 10 and 11 containing -oxo ligands
m-oxo
m
m
can be explained by the fact that bis(iminopyrrolyl)Fe(II) com-
plexes, formed by substitution of the two chlorine atoms by two
iminopyrrolyl ligands, are highly unsaturated (15-electron species).
As a consequence, they are highly reactive towards adventitious
water molecules (or less probably towards oxygen or THF) present
in the solvent, leading to oxidised products, which are more satu-
rated and thus more stable than the parent Fe(II) complexes. The
difference between the two complexes can be rationalised in terms
of their workup. In fact, the absence of the isopropyl groups in the
N-aryl substituent confers insolubility to 10 in nonpolar solvents,
such as n-hexane, and required the use of a more polar solvent such
as Et2O in the reaction workup. This solvent has an oxygen atom
that can be easily coordinated to Na ions present in solution [14],
whereas in the case of complex 11, the use of n-hexane (a non-
coordinating solvent) did not allow the formation of a compound
similar to 10, giving rise instead to a dimer bearing only a single
The last metal to be investigated in this work was copper, in the
oxidation state þ1. The synthetic methodology used was the gen-
eral procedure described previously, consisting in the reaction of
the deprotonated ligand precursor II with CuBr, affording complex
13, as an off-white solid, in 57% yield. The elemental analyses
showed that this compound had an iminopyrrolyl ligand:Cu
composition of 1:1. On the other hand, the Electron-Spray Ionisa-
tion (ESI) mass spectrum indicated an m/z of 633, in agreement
with the formulation [Cu(iminopyrrolyl)]2. The 1H NMR spectrum,
obtained at room temperature, exhibited a pattern that pointed to a
mixture of isomers, present in a ratio of 1:2, or alternatively to an
intramolecular fluxional process occurring in a species containing
non-equivalent iminopyrrolyl ligands, in a ratio of 1:2. Variable-
temperature (VT) 1H NMR experiments in toluene-d8, from room
temperature to 100 ꢁC, have demonstrated that resonances
belonging to equivalent groups tend to coalesce in one, but
only above 100 ꢁC (see Fig. S1 of Supplementary material and
Experimental section). Unfortunately, no crystals suitable for
X-ray diffraction were so far obtained. In the absence of further
evidence, the only conclusion that can be drawn is that 13 is a
polynuclear copper(I) species with the general formulation [Cu(i-
minopyrrolyl)]x (Scheme 3).
bridging m-oxo ligand.
In order to prevent the formation of these dimeric complexes,
and the simultaneous oxidation from Fe(II) to Fe(III), we have
investigated the same type of reaction in the presence of a neutral
ligand, such as pyridine (Py), that could coordinate to the metal
centre and improve the stability of the resulting compound. The
deprotonation of two equivalents of ligand precursor I with NaH,
followed by reaction with FeCl2, in the presence of two equiva-
lents of Py, afforded complex 12 as highly sensitive orange-red
paramagnetic crystals, in 44% yield (Scheme 2), which structure
was determined by X-ray diffraction (see Section 2.2). This
compound was also characterised by 1H NMR spectroscopy, in
CD2Cl2, displaying resonances belonging to a paramagnetic spe-
cies with chemical shifts spread between ca. 47 and ꢀ2 ppm. In
fact, despite the increased stabilisation of Fe(II) centres
During the workup of the latter reaction, after removal of the
solvent under vacuum, the residue was washed with n-hexane, and
a pale yellow/almost colourless solution was filtered into a beaker
exposed to air. The solvent of this solution was evaporated under
vacuum and the obtained greenish precipitate was recrystallised
from n-hexane, at ꢀ20 ꢁC, giving black crystals, suitable for X-ray
diffraction (see Section 2.2) of the bis(iminopyrrolyl)-Cu(II) com-
plex 14 (Scheme 3).
Fig. 1. Fe(III) compounds 10 and 11 formed by oxidation of the corresponding bis(iminopyrrolyl) Fe(II) derivatives.
Scheme 2. Synthesis of bis(iminopyrrolyl) Fe(II) pyridine complex 12.

C.S.B. Gomes et al. / Journal of Organometallic Chemistry 760 (2014) 167e176
171
Zn(II) complex [9], the imine bond distances N2eC6, which lie in
ꢀ
the range 1.300(12)e1.346(12) A, exhibit longer bond lengths than
ꢀ
the corresponding distance in the free ligand I (ca. 1.281(2) A) [5],
showing a certain extent of steric congestion around the Ni centre
and
pep* back-bonding from the metal to the iminic fragment.
The features exhibited for ligand precursor I [5] only change
slightly upon coordination to Ni, being comparable to those
observed for similar compounds in earlier publications of our
group [5e9].
Complex 10 (Fig. 2) crystallised as a dimer with penta-
coordinated Fe(III) metal centres, where the geometry around
these atoms, generated by two iminopyrrolyl ligands and one
oxygen atom, can be described as distorted trigonal bipyramidal
(
s
value of 0.76). In a pentacoordinated structure, the
eter, )/60, measures the degree of distortion within the
¼ (
structural continuum between trigonal bipyramidal and square
pyramidal geometries (
¼ 1 for an ideal trigonal bipyramid and
¼ 0 for an ideal square pyramid) [15]. The axial positions are
s param-
s
bea
s
s
occupied by the neutral imine groups of both bidentate ligands,
that are trans to each other, with an almost linear N2eFe1eN20
axis (175.8(2)ꢁ), being the Fe1eNimine bonds (2.274(7) and
2.311(7) Ǻ), the longest distances to the metal centre (Table 2).
On the other hand, the pyrrolyl rings and the oxygen atom
occupy the remaining equatorial positions. Moreover, this oxygen
atom is bonded to two sodium atoms that are also bridging the
oxygen atom of the other Fe trigonal bipyramid. A further Et2O
molecule is coordinated to each of these sodium atoms, giving
rise to a trigonal planar geometry around each Na. Although the
features exhibited for the ligand precursor I only change slightly
upon coordination to Fe, being similar to those observed for the
Ni(II) complexes 5 and 7, the chelate bite angles N1eFe1eN2 are
ca. 75ꢁ, being smaller than those observed for the referred
compounds.
In the case of compound 11, which also crystallised as a dimer
(Fig. 2), its structure can be described as two bis(iminopyrrolyl)
iron fragments connected by a bridging oxygen atom, where the
geometry around each Fe(III) atom is that of a distorted trigonal
bipyramid (s parameters of 0.69 and 0.60, respectively; Table 2).
In this complex, the anionic pyrrolyl rings are closer to the axial
positions, with angles N1eFe1eN3 of ca. 156ꢁ, whereas the
two Nimine groups and the oxygen atom occupy the equatorial
positions. The shortest bond distances to the metal centre are
those between the bridging oxygen and the Fe(III) atoms
(1.779(4) and 1.773(4) Ǻ, respectively). All the remaining
features regarding the iminopyrrolyl ligand are in agreement
with those described previously (see above). The Fe(II) com-
pound studied, complex 12, is formed by two iminopyrrolyl li-
gands and a pyridine molecule coordinated to the metal centre,
Scheme 3. Synthesis of Cu(I) and Cu(II) complexes 13 and 14, respectively.
2.2. X-ray diffraction studies
Crystals suitable for X-ray diffraction were obtained for com-
pounds 5, 7, 10e12, and 14, enabling the determination of their
molecular and crystal structures. Perspective views of the molec-
ular structures of these bis(iminopyrrolyl) complexes are shown in
Fig. 2 and the corresponding selected bond distances and angles are
given in Tables 1 and 2.
showing an intermediate geometry in between
a distorted
trigonal bipyramid and a square pyramid (Fig. 2 and Table 2). The
Nimine groups occupy the distorted axial positions (NeFeeN ca.
165ꢁ), while the anionic pyrrolyl rings and the pyridine molecule
fill the equatorial positions. The degree of distortion exhibited in
The crystal structures of complexes 5 and 7 (Fig. 2 and Table 1)
are very similar, revealing a four-coordinate nickel centre, with
distorted square planar geometry, where the two iminopyrrolyl
ligands are coordinated in a transoid conformation. The dihedral
this compound (s parameter of 0.48) is higher than those
observed for complexes 10 or 11. The shortest bond around the
metal centre is Fe1eNpyrrolyl, whereas FeeNpyridine has an inter-
mediate length between the former Fe1eNpyrrolyl and that of
angle
a
, defined in Table 1, measures the degree of distortion
Fe1eNimine.
observed for this imaginary square plane. The values are small
(1.48e19.19ꢁ), the higher and smaller distortions being observed
for molecules 2 and 3 of complex 5, respectively. In complexes 5
and 7, the chelate bite angles of both ligands, N1eNi1eN2, are ca.
83ꢁ. Despite the similarity of the NieNpyrrolyl and NieNimine bond
lengths, the NieNpyrrolyl ones are slightly shorter. As observed in a
previous publication for a bis(iminophenanthro[9,10-c]pyrrolyl)
Complex 14 (Fig. 2) shows a four-coordinate copper centre with
distorted square planar geometry, where the two iminopyrrolyl
ligands appear in a transoid conformation. The dihedral angle
a
(defined in Table 2), which measures the degree of distortion
observed for this imaginary square plane, has a small value of
15.38ꢁ. The chelate bite angle, N1eCu1eN2, is ca. 82ꢁ, and the Cue
Npyrrolyl bond lengths, despite being very similar to those of the

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C.S.B. Gomes et al. / Journal of Organometallic Chemistry 760 (2014) 167e176
Table 1
ꢁ
ꢀ
Selected bond distances (A) and angles ( ) for complexes 5 and 7.
5
7
Molecule 1
Ligand 1
Molecule 2
Molecule 3
Ligand 1
Molecule 1
Ligand 1
Ligand 2
Ligand 1
Ligand 2
Ligand 2
Ligand 2
ꢀ
Distances (A)
N1eC2
N1eC5
C3eC2
C3eC4
C5eC4
C6eC2
N2eC6
N2eC7
1.384(12)
1.349(12)
1.376(13)
1.382(13)
1.400(13)
1.438(13)
1.300(12)
1.423(12)
1.891(8)
1.371(12)
1.354(12)
1.404(13)
1.355(13)
1.403(13)
1.411(14)
1.328(12)
1.436(12)
1.902(8)
1.361(12)
1.330(12)
1.417(12)
1.362(13)
1.413(14)
1.404(13)
1.321(12)
1.459(12)
1.907(8)
1.378(12)
1.344(12)
1.424(12)
1.397(12)
1.418(13)
1.406(13)
1.313(12)
1.429(12)
1.897(8)
1.353(11)
1.381(12)
1.418(13)
1.372(13)
1.403(14)
1.399(13)
1.346(12)
1.447(12)
1.913(8)
1.415(12)
1.348(12)
1.408(14)
1.397(14)
1.436(14)
1.403(14)
1.320(12)
1.472(11)
1.908(8)
1.390(5)
1.342(5)
1.427(6)
1.398(6)
1.412(6)
1.391(6)
1.323(5)
1.436(5)
1.891(3)
1.904(4)
1.388(5)
1.346(5)
1.415(6)
1.398(6)
1.409(6)
1.399(5)
1.325(5)
1.429(5)
1.899(3)
1.911(4)
Ni1eN1
Ni1eN2
1.917(8)
1.914(7)
1.914(7)
1.928(7)
1.942(7)
1.934(8)
Angles (ꢁ)
C6eN2eC7
N1eC2eC6
N2eC6eC2
C3eC2eC6
N1eC2eC3
C2eC3eC4
C5eC4eC3
N1eC5eC4
C5eN1eC2
N1eNi1eN2
Dihedral aa
119.9(8)
112.2(9)
116.2(9)
137.1(10)
110.7(8)
106.4(9)
105.7(8)
110.3(9)
105.5(8)
83.6(3)
117.9(8)
113.9(9)
115.1(10)
135.8(10)
110.1(9)
106.3(9)
107.6(9)
109.8(10)
105.9(8)
83.2(4)
117.5(7)
114.9(9)
115.6(9)
135.5(10)
109.6(8)
105.4(9)
108.1(10)
109.0(9)
108.0(9)
83.7(3)
119.9(8)
114.8(8)
115.9(9)
135.0(10)
110.1(8)
104.8(8)
108.0(9)
109.4(9)
107.7(8)
84.0(4)
115.3(8)
113.0(9)
117.4(9)
134.9(10)
111.4(8)
104.5(9)
109.3(10)
108.2(9)
106.5(8)
82.7(4)
115.5(8)
115.6(9)
114.1(9)
133.7(10)
109.9(9)
106.4(9)
107.0(9)
110.2(9)
106.5(8)
83.3(4)
118.1(4)
112.6(4)
117.4(4)
138.9(4)
108.4(4)
106.6(4)
106.6(4)
110.6(4)
107.9(4)
83.77(15)
17.45
117.4(4)
112.5(4)
117.4(4)
138.6(4)
108.8(4)
106.2(4)
107.4(4)
109.6(4)
108.0(3)
83.82(15)
17.00
19.19
1.48
a
Dihedral
a
¼ angle between planes [(N1, Ni1, N2), ligand 1] and [(N1, Ni1, N2), ligand 2].
CueNimine groups, are slightly shorter. The features exhibited for
ligand precursor II [5] only change slightly upon coordination to
Cu, as it can be seen in Table 1, and are comparable to those
observed for similar compounds in earlier publications of our
group [5e9].
3. Conclusions
Several nickel, cobalt, iron and copper complexes containing
two iminopyrrolyl or two iminophenanthro[9,10-c]pyrrolyl ligands
were synthesised and characterised by multiple methods. X-ray
crystallography studies revealed chelation of these ligands to the
Table 2
ꢁ
ꢀ
Selected bond distances (A) and angles ( ) for complexes 10e12, and 14.
10a
11
12b
14
Ligand 1
Ligand 2
Ligand 1
Ligand 2
Ligand 3
Ligand 4
Ligand 1
Ligand 2
ꢀ
Distances (A)
N1eC2
N1eC5
C3eC2
C3eC4
C5eC4
C6eC2
N2eC6
N2eC7
Fe1eN1
Fe1eN2
Fe1eO1
Na1eO1
Na1eO2
Fe1eN3
1.387(11)
1.359(11)
1.373(10)
1.385(11)
1.363(11)
1.373(11)
1.333(11)
1.424(10)
2.054(6)
2.274(7)
1.973(5)
2.263(6)
2.289(6)
e
1.360(10)
1.323(11)
1.371(12)
1.397(12)
1.400(12)
1.386(13)
1.333(12)
1.376(11)
2.047(7)
1.383(8)
1.338(9)
1.374(10)
1.397(10)
1.387(10)
1.407(10)
1.295(9)
1.424(8)
2.057(6)
2.148(5)
1.779(4)
e
1.377(9)
1.358(9)
1.409(10)
1.386(10)
1.388(10)
1.433(10)
1.296(9)
1.432(9)
2.058(6)
2.172(6)
1.388(8)
1.311(9)
1.404(10)
1.362(11)
1.422(10)
1.371(9)
1.308(8)
1.415(9)
2.078(5)
2.142(6)
1.773(4)
e
1.381(9)
1.330(9)
1.401(10)
1.381(11)
1.406(10)
1.435(10)
1.268(8)
1.410(9)
2.048(6)
2.167(6)
1.365(3)
1.352(3)
1.394(3)
1.379(3)
1.384(3)
1.412(3)
1.295(3)
1.411(2)
2.0543(18)
2.2158(18)
e
1.381(3)
1.354(3)
1.393(4)
1.378(4)
1.395(4)
1.407(4)
1.301(3)
1.432(3)
1.373(3)
1.352(3)
1.394(4)
1.389(4)
1.387(4)
1.411(4)
1.296(3)
1.434(3)
2.311(7)
e
e
e
e
e
e
e
e
e
e
e
e
e
2.110(3)
Cu1eN1
Cu1eN2
Angles (ꢁ)
N1eFe1eN2
N1eFe1eO1
N2eFe1eO1
N1eFe1eN3
N2eFe1eN3
N1eCu1eN2
1.957(2)
2.029(2)
1.957(2)
2.021(2)
75.3(3)
130.1(2)
90.4(2)
e
75.7(3)
121.0(2)
93.4(2)
e
79.0(2)
100.3(2)
119.3(2)
e
77.7(2)
102.8(2)
125.0(2)
e
78.8(2)
102.6(2)
117.6(2)
e
77.0(2)
101.5(2)
121.9(2)
e
78.31(7)
e
e
111.76(5)
97.38(5)
e
e
e
e
e
e
82.32(9)
15.38
82.45(9)
s
parameter [15]
0.76
0.69
0.60
0.48
Dihedral ac
a
In complex 10, half molecule is generated by the symmetry operation ꢀx þ 2, ꢀy, ꢀz.
b
c
In complex 12, half molecule is generated by the symmetry operation ꢀx þ 1, y, ꢀz þ 1/2.
Dihedral
¼ angle between planes [(N1, Cu1, N2), ligand 1] and [(N1, Cu1, N2), ligand 2].
a

C.S.B. Gomes et al. / Journal of Organometallic Chemistry 760 (2014) 167e176
173
Fig. 2. Perspective views of the molecular structures of bis(iminopyrrolyl) complexes 5, 7, 10e12, and 14, with 50% probability level ellipsoids. All hydrogen atoms were omitted for
clarity. In the case of compound 7, two co-crystallised CH2Cl2 molecules were also omitted.
metal centres, resulting in complexes with different geometries.
Nickel(II) compounds presented distorted square planar geome-
tries around the metal centre, whereas for cobalt, a tetrahedral
complex is proposed.
corresponding bis(iminopyrrolyl) Cu(II) complex, whose molecular
structure was determined by X-ray diffraction.
4. Experimental section
In an attempt to prepare homoleptic bis(iminopyrrolyl)iron
complexes, from the reaction of FeCl2 with the corresponding
iminopyrrolyl sodium salts, only complexes 10 and 11 were iden-
tified by X-ray diffraction. The resulting structure of 10 is a dimer
with pentacoordinated Fe(III) metal centres, where the geometry
around these atoms, generated by two iminopyrrolyl ligands and a
4.1. General considerations
All experiments dealing with air- and/or moisture-sensitive
materials were carried out under inert atmosphere using a dual
vacuum/nitrogen line and standard Schlenk techniques. Nitrogen
gas was supplied in cylinders (Air Liquide) and purified by passage
through 4 Ǻ molecular sieves. Unless otherwise stated, all reagents
were purchased from commercial suppliers (e.g., Acrös, Aldrich,
Fluka) and used without further purification. All solvents to be used
under inert atmosphere were thoroughly deoxygenated and
dehydrated before use. They were dried and purified by refluxing
over a suitable drying agent followed by distillation under nitrogen.
The following drying agents were used: sodium (for toluene,
diethyl ether, and tetrahydrofuran (THF)) and calcium hydride (for
n-hexane and dichloromethane). Solvents and solutions were
transferred using a positive pressure of nitrogen through stainless
steel cannulae and mixtures were filtered in a similar way using
modified cannulae that could be fitted with glass fibre filter disks.
Nuclear magnetic resonance (NMR) spectra were recorded on
Bruker Avance III 300 or Bruker Avance III 400 (1H and 13C) spec-
trometers. Deuterated solvents were dried by storage over 4 Ǻ
molecular sieves and degassed by the freeze-pump-thaw method.
Spectra were referenced internally to residual protio-solvent (1H)
or solvent (13C) resonances and are reported relative to tetrame-
m
-oxo ligand, can be described as distorted trigonal bipyramidal.
The oxygen atom is bonded to two sodium atoms that are also
bridging the -oxo ligand of the other trigonal bipyramidal Fe
m
centre. To each of these sodium atoms, a further Et2O molecule is
coordinated, giving rise to a trigonal planar geometry around each
Na. Conversely, compound 11 crystallised as a dimer, composed by
two bis(iminopyrrolyl)iron fragments connected by
a single
bridging oxygen atom, where a distorted trigonal bipyramidal ge-
ometry around each Fe(III) is also exhibited. In order to prevent the
formation of these dimeric complexes, and the simultaneous
oxidation of Fe(II) to Fe(III), we performed the same type of reaction
in the presence of a neutral ligand, pyridine (Py), that coordinated
to the metal centre and improved the stability of the resulting
compound. In fact, a 16-electron Fe(II) complex was isolated
showing an intermediate geometry in between a distorted trigonal
bipyramid and a square pyramid.
The reaction of CuBr with 2,6-diisopropylphenylformimino
pyrrolyl sodium salt afforded a complex, whose proposed struc-
ture is that of a dimer with the general formulation [Cu(imino-
pyrrolyl)]x. When exposed to air, this complex gives rise to the
thylsilane (
d
¼ 0). All chemical shifts are quoted in
d (ppm) and

174
C.S.B. Gomes et al. / Journal of Organometallic Chemistry 760 (2014) 167e176
coupling constants given in Hz. Multiplicities were abbreviated as
follows: broad (br), singlet (s), doublet (d), triplet (t), quartet (q),
heptet (sep), and multiplet (m). For air- and/or moisture sensitive
materials, samples were prepared in J. Young NMR tubes in a
glovebox.
Elemental analyses were obtained from the IST elemental
analysis services. The ESI mass spectra were obtained in a 500-MS
Ion Trap mass spectrometer, Varian Inc. The operating parameters
were as follows: the spray needle voltage was set at þ5 kV, nitrogen
was used both as nebulising and drying gas (25 psi and 10 psi,
respectively), drying gas temperature 350 ꢁC; the capillary voltage
and the RF loading were optimised for each ion under study.
NiBr2, CoCl2, FeCl2 and CuBr were available in the laboratory,
dried under vacuum, at 100 ꢁC, for several hours to constant weight
and stored under nitrogen atmosphere. Ligand precursors IeIV
were prepared according to literature procedures [5e9].
diffraction. Yield: 0.13 g (74%). Anal. Calcd. for C46H30N4Ni$0.7CH2Cl2,
obtained (calculated): C, 78.09 (78.10); H, 4.04 (4.30); N, 7.90 (7.90).
1H NMR (300 MHz, CD2Cl2):
d 8.97 (br, 2H, H15 or H12), 8.76 (d, 2H,
3JHH ¼ 8.0 Hz, H18 or H9), 8.65 (br, 2H, H12 or H15), 8.54 (br, 2H, H11
3
or H16), 8.47 (d, 2H, JHH ¼ 7.4 Hz, H16 or H11), 8.29 (d, 2H,
3JHH ¼ 7.6 Hz, H18 or H9), 8.19e8.07 (m, 6H, N]CH, H10 and H17),
7.75e7.59 (m, 4H, Ph-Hortho), 7.57e7.43 (m, 6H, Ph-Hmeta and
Ph-Hpara), 6.19 (s, 2H, H5). 13C{1H} NMR (100 MHz, CD2Cl2):
d 159.1
(N]CH), 150.6 (Ph-Cipso), 135.2 (Ph-Cortho), 130.6 (C14 or C13), 130.3
(C13 or C14), 129.6 (Ph-Cmeta), 128.2 (C8 or C19), 127.9 (C8 or C19),
127.5 (C9 or C18), 127.4 (C4 or C3), 127.3 (C3 or C4), 127.1 (C18 or C9),
126.5 (C16 or C11),125.6 (Ph-Cpara),125.1 (C17 and C10),125.0 (C11 or
C16), 124.2 (C12 or C15), 123.6 (C15 or C12), 122.7 (C5), 119.4 (C2).
4.2.4. [Ni(k2N,N0-NC16H9C(H)]N-2,6-iPr2C6H3)2] (8)
The same procedure described for the synthesis of 6 was fol-
lowed, but a solution of sodium salt 4 prepared in situ (0.21 g,
0.5 mmol) was employed. After extraction of the reaction products
with toluene, the resulting solution was concentrated and stored
at ꢀ20 ꢁC, giving a dark brown solid of 8. Yield: 0.080 g (37%). Anal.
Calcd. for C58H54N4Ni$2H2O, obtained (calculated): C, 76.91 (77.25);
H, 6.25 (6.48); N, 5.74 (6.21). ESI-MS: m/z 865 [M þ H]þ (calculated
4.2. Syntheses
4.2.1. [Ni(k2N,N0-NC4H3C(H)]NeC6H5)2] (5)
Anhydrous nickel bromide (0.11 g, 0.5 mmol) was suspended in
tetrahydrofuran and cooled to ꢀ80 ꢁC. A solution of sodium salt 1
prepared in situ (0.19 g, 1.0 mmol) was filtered and directly added
dropwise to the suspension, which was then stirred for 1 h. The
mixture was allowed to warm to room temperature and further
stirred overnight. All volatiles were evaporated and the resulting
residue was washed with n-hexane and extracted with diethyl
ether until extracts were colourless. The resulting orange-yellowish
solution was concentrated and cooled to ꢀ20 ꢁC, yielding a
brownish-orange powder of 5. Yield: 0.033 g (15%). 1H NMR
for C58H55N4Ni [M þ H]þ, 865). 1H NMR (300 MHz, C6D6):
d 8.37 (dd,
3
4
2H, JHH ¼ 7.8 Hz and JHH ¼ 1.6 Hz, H15 or H12), 8.33 (d, 2H,
3
3JHH ¼ 8.3 Hz, H9 or H18), 8.84 (dd, 2H, JHH ¼ 7.4 Hz and
3
4JHH ¼ 1.6 Hz, H12 or H15), 7.79 (dd, 2H, JHH ¼ 8.0 Hz and
4JHH ¼ 0.8 Hz, H18 or H9), 7.76 (s, 2H, N]CH), 7.49e7.39 (m, 4H, H16
and H11), 7.31e6.99 (m, 10 H, H10, H17, Ph-Hmeta and Ph-Hpara), 6.16
3
(s, 2H, H5), 4.66 (sep, 4H, JHH ¼ 6.8 Hz, CH(CH3)2), 1.24 (d, 24H,
3JHH ¼ 6.8 Hz, CH(CH3)2). 1H NMR (400 MHz, toluene-d8):
d 8.29 (d,
(300 MHz, CD2Cl2):
d
8.27 (s, 2H, N]CH), 7.36 (br, 4H, Ph-Hortho),
2H, 3JHH ¼ 7.8 Hz, H15 or H12), 8.24 (d, 2H, 3JHH ¼ 8.2 Hz, H9 or H18),
3
4
7.17 (br, 6H, Ph-Hmeta and Ph-Hpara), 7.00 (s, 2H, H5), 6.67 (m, 2H,
H3), 6.30 (m, 2H, H4).
7.84 (dd, 2H, JHH ¼ 7.8 Hz and JHH ¼ 1.3 Hz, H12 or H15), 7.74 (s,
3 4
2H, N]CH), 7.55 (dd, 2H, JHH ¼ 8.0 Hz and JHH ¼ 0.8 Hz, H18 or
H9), 7.40e7.34 (m, 4H, H16 and H11), 7.27e7.16 (m, 10 H, H10, H17,
Ph-Hmeta and Ph-Hpara), 5.94 (s, 2H, H5), 4.58 (sep, 4H, 3JHH ¼ 6.9 Hz,
4.2.2. [Ni(k2N,N0-NC4H3C(H)]N-2,6-iPr2C6H3)2] (6)
3
This compound was already reported in the literature, although
synthesised by slightly different methods (deprotonation with LiBu
and Et2O as solvent [11]; deprotonation with NaH and acetonitrile
as solvent [12]). [NiBr2(DME)] (0.14 g, 0.5 mmol) was suspended in
tetrahydrofuran and cooled to ꢀ80 ꢁC. A solution of sodium salt 2
prepared in situ (0.27 g, 1.0 mmol) was filtered and directly added
dropwise to the suspension, which was then stirred for 1 h. The
mixture was allowed to warm to room temperature and further
stirred overnight. All volatiles were evaporated and the resulting
residue was extracted with n-hexane until extracts were colourless.
The resulting orange-brownish solution was concentrated and
cooled to ꢀ20 ꢁC, yielding a brown microcrystalline solid of 6.
CH(CH3)2), 1.23 (d, 12H, JHH ¼ 6.9 Hz, CH(CH3)2), 1.20 (d, 12H,
3JHH ¼ 6.8 Hz, CH(CH3)2). 13C {1H} NMR (100 MHz, C6D6):
d 160.4
(N]CH), 146.1 (Ph-Cipso), 145.0 (Ph-Cortho), 135.2 (C13 or C14), 134.2
(C14 or C13), 130.8 (C9 and C18), 129.3 (C4 or C3), 129.0 (C3 or C4),
128.7 (C19 or C8), 127.9 (Ph-Cmeta), 127.5 (C8 or C19), 127.2 (C17 or
C10), 126.2 (C10 or C17), 125.0 (C2), 124.8 (C16 or C11), 124.7 (C11 or
C16), 124.6 (Ph-Cpara), 124.4 (C15 and C12), 123.9 (C12 or C15), 122.6
(C5), 29.4 (CH(CH3)2), 24.8 (CH(CH3)2), 23.0 (CH(CH3)2).
4.2.5. [Co(k2N,N0-NC16H9C(H)]N-2,6-iPr2C6H3)2] (9)
The same procedure described for the synthesis of6 was followed,
but a solution of sodium salt 4 prepared in situ (0.32 g, 0.75 mmol)
was employed, and added to CoCl2 (40 mg, 0.31 mmol). After
extraction of the reaction products with toluene, the resulting solu-
tion was concentrated and stored at ꢀ20 ꢁC, giving a brown-reddish
paramagnetic solid of 9. Attempts to obtain crystals suitable for X-ray
diffraction were carried out by recrystallisation of the obtained
powder from Et2O, but no single crystals were obtained. Yield: 0.25 g
(91% based on CoCl2). Anal. Calcd. for C58H54N4Co$C4H10O, obtained
(calculated): C, 78.65 (79.21); H, 6.79 (6.86); N, 6.19 (5.96). ESI-MS: m/
z 866 [M þ H]þ (calculated for C58H55N4Co [M þ H]þ, 866). 1H NMR
Yield: 0.24 g (84%). 1H NMR (300 MHz, C6D6):
d 7.31e7.13 (m, 6H,
Ph-Hmeta and Ph-Hpara), 6.69 (s, 2H, N]CH), 6.66 (dd, 2H,
3JHH ¼ 3.7 Hz and 4JHH ¼ 0.9 Hz, H5), 6.06 (dd, 2H, 3JHH ¼ 3.8 Hz and
4JHH ¼ 2.0 Hz, H3), 5.22e5.21 (m, 2H, H4), 4.60 (sep, 4H,
3JHH ¼ 6.9 Hz, CH(CH3)2), 1.38 (d, 12H, 3JHH ¼ 6.6 Hz, CH(CH3)2), 1.3
3
(d, 12H, JHH ¼ 6.9 Hz, CH(CH3)2). 13C{1H} NMR (75 MHz, C6D6):
d
161.8 (N]CH), 145.7 (Ph-Cipso), 143.9 (Ph-Cortho), 140.6 (C2), 138.4
(C4), 127.5 (Ph-Cpara), 124.0 (Ph-Cmeta), 119.2 (C5), 113.1 (C3), 29.2
(CH(CH3)2), 24.6 (CH(CH3)2), 22.8 (CH(CH3)2).
(400 MHz, CD2Cl2): d 20.52 (s, 2H),14.65 (s, 2H),13.96 (s, 2H),12.52 (s,
4.2.3. [Ni(k2N,N0-NC16H9C(H)]NeC6H5)2] (7)
2H), 5.01 (s, 2H), 3.99 (br,10H), 3.42 (q, 4H, 3JHH ¼ 6.9 Hz, (CH3CH2)O),
3.22 (s, 2H),1.14 (t, 6H, 3JHH ¼ 6.9 Hz, (CH3CH2)O), 0.09 (s,16H), ꢀ3.26
(s, 4H), ꢀ6.54 (s, 2H), ꢀ25.97 (br, 10H).
The same procedure described for the synthesis of 6 was fol-
lowed, but a solution of sodium salt 3 prepared in situ (0.17 g,
0.5 mmol) was employed. Extraction of the reaction products with
toluene, until extracts remained colourless, and removal of the sol-
vent by vacuum evaporation, afforded a brown powder, which was
recrystallised in CH2Cl2 and double-layered with n-hexane,
at ꢀ20 ꢁC, giving bronze crystals of 7b, which were suitable for X-ray
4.2.6. Attempt to synthesise [Fe(k2N,N0-NC4H3C(H)]NeC6H5)2]
The same procedure described for the synthesis of 8 was fol-
lowed, but a solution of sodium salt 1 prepared in situ (0.19 g,
1.0 mmol) was employed, and added to FeCl2 (65 mg, 0.5 mmol).

C.S.B. Gomes et al. / Journal of Organometallic Chemistry 760 (2014) 167e176
175
After extraction of the reaction products with Et2O, the resulting
solution was concentrated, double-layered with n-hexane and
stored at ꢀ20 ꢁC. However, the reaction product was highly un-
stable, easily decomposing from red crystals to a brownish powder.
Nevertheless, it was still possible to isolate from the mixture very
few crystals of 10, which were suitable enough for X-ray diffraction,
allowing the determination of its crystal structure.
washed with n-hexane. The remaining product was extracted with
toluene, and the resulting solution was concentrated, double
layered with n-hexane (1:3), and stored at ꢀ20 ꢁC, giving an off-
white solid of 13. Yield: 0.18
g (57%). Anal. Calcd. for
C
34H42N4Cu2, obtained (calculated): C, 63.78 (64.43); H, 6.83 (6.68);
N, 8.73 (8.84). ESI-MS: m/z 633 [M
þ
H]þ (calculated for
C
34H43N4Cu2 [M þ H]þ, 633). 1H NMR (400 MHz, C6D6): Admitting
that two isomers (13A and 13B) were observed at room tempera-
ture in a ratio 2:1 (13A:13B), which was invariant with tempera-
4.2.7. Attempt to synthesise [Fe(k2N, N0-NC4H3C(H)]N-iPr2C6H3)2]
The same procedure described for the synthesis of 6 was fol-
lowed, but a solution of sodium salt 2 prepared in situ (0.27 g,
1.0 mmol) was employed, and added to FeCl2 (65 mg, 0.5 mmol).
After extraction of the reaction products with n-hexane, the
resulting solution was concentrated and stored at ꢀ80 ꢁC. However,
the reaction product was highly unstable, easily decomposing from
black crystals to a brownish powder. Nevertheless, it was still
possible to isolate from the mixture very few crystals of 11, which
were suitable enough for X-ray diffraction, allowing the determi-
nation of its crystal structure.
ture, their NMR spectra are reported as follows: 13A
d 7.52e6.82
(m, 6H, N]CH, Ph-Hmeta, Ph-Hpara, H5 and H3), 6.51 (dd, 1H,
4
3
3JHH ¼ 3.6 Hz and JHH ¼ 1.7 Hz, H4), 3.20 (sep, 2H, JHH ¼ 6.8 Hz,
3
CH(CH3)2), 1.0 (d, 6H, JHH ¼ 6.8 Hz, CH(CH3)2), 0.80 (d, 6H,
3JHH ¼ 6.8 Hz, CH(CH3)2). 13B
d 7.52e6.82 (m, 6H, N]CH, Ph-Hmeta,
Ph-Hpara, H5 and H3), 6.43 (dd, 1H, 3JHH ¼ 3.5 Hz and 4JHH ¼ 1.7 Hz,
3
H4), 3.48 (sep, 2H, JHH
¼
6.8 Hz, CH(CH3)2), 1.20 (d, 6H,
3JHH ¼ 6.8 Hz, CH(CH3)2), 1.06 (d, 6H, JHH ¼ 6.8 Hz, CH(CH3)2). 1H
3
NMR (300 MHz, toluene-d8): 13A
d 7.52e6.88 (m, 6H, N]CH, Ph-
H
meta, Ph-Hpara, H5 and H3), 6.46 (br, 1H, H4), 3.18 (sep, 2H,
3
3JHH ¼ 6.8 Hz, CH(CH3)2), 1.0 (d, 6H, JHH ¼ 6.8 Hz, CH(CH3)2), 0.79
4.2.8. [Fe(k2N,N0-NC4H3C(H)]NeC6H5)2(NC5H5)] (12)
(d, 6H, JHH ¼ 6.8 Hz, CH(CH3)2). 13B
d 7.52e6.88 (m, 6H, N]CH,
3
The same procedure described for 6 was followed, but a solution
of sodium salt 1 prepared in situ (0.20 g, 1.03 mmol) was employed,
and added to a suspension of FeCl2 (65 mg, 0.5 mmol) and pyridine
(1 mL, 12.34 mmol). The residue was washed with n-hexane, Et2O
and toluene. After extraction of the reaction products with THF, the
resulting solution was concentrated and stored at ꢀ20 ꢁC, giving
highly sensitive orange-red paramagnetic crystals of 12, suitable for
X-ray diffraction. Yield: 0.15 g (64%). Anal. Calcd. for C27H23N5Fe,
obtained (calculated): C, 67.80 (68.51); H, 4.54 (4.90); N, 11.02
(14.79). 1H NMR (300 MHz, CD2Cl2): 47.07 (s, 1H), 32.61 (br, 1H),
26.83 (s, 1H), 19.85 (s, 2H), 3.02 (s, 7H), 1.65 (s, 3H), ꢀ0.24 (s,
5H), ꢀ2.04 (br, 7H).
Ph-Hmeta, Ph-Hpara, H5 and H3), 6.46 (br, 1H, H4), 3.47 (sep, 2H,
3JHH ¼ 6.8 Hz, CH(CH3)2), 1.21 (d, 6H, 3JHH ¼ 6.8 Hz, CH(CH3)2), 1.01
(d, 6H, JHH ¼ 6.8 Hz, CH(CH3)2). 13C{1H} NMR (300 MHz, C6D6):
3
13A
d 161.9 (N]CH), 146.3 (Ph-Cipso), 141.8 (Ph-Cortho), 141.3 (C4),
135.1 (C2), 129.3 (C5), 126.6 (Ph-Cpara), 123.9 (Ph-Cmeta), 113.9 (C3),
28.6 (CH(CH3)2), 23.8 (CH(CH3)2), 22.8 (CH(CH3)2). 13B 161.8 (N]
d
CH), 146.2 (Ph-Cipso), 142.1 (Ph-Cortho), 141.0 (C4), 134.8 (C2), 126.9
(C5), 125.7 (Ph-Cpara), 124.2 (Ph-Cmeta), 113.8 (C3), 28.7 (CH(CH3)2),
24.0 (CH(CH3)2), 23.6 (CH(CH3)2).
4.2.10. Isolation of [Cu(k2N,N0-NC4H3C(H)]N-2,6-iPr2C6H3)2] (14)
The pale yellow solutions resulting from the n-hexane washings
of compound 13 in the previous reaction were filtered into a beaker
under O2/moisture atmosphere. The solvent was evaporated under
vacuum and recrystallised from n-hexane at ꢀ20 ꢁC, giving black
crystals of 14. Yield: 0.097 g (17%). Anal. Calcd. for C34H42N4Cu$H2O,
obtained (calculated): C, 70.02 (69.42); H, 7.82 (7.54); N, 9.49 (9.52).
4.2.9. [Cu(k2N,N0-NC4H3C(H)]N-2,6-iPr2C6H3)]x (13)
The same procedure described for 6 was followed, but a solu-
tion of sodium salt 2 prepared in situ (0.27 g, 1.0 mmol) was
employed, and added to CuBr (0.14 g, 1.0 mmol). The residue was
Table 3
Crystallographic data for 5, 7, 10e12 and 14.
5
7
10
11
12
14
Formula
C22H18N4Ni
397.09
0.71073
150
C48H34Cl4N4Ni
867.30
0.71073
150
C26H28FeN4NaO2
507.36
0.71073
150
C68H84Fe2N8O
1141.13
0.71073
150
C27H23FeN5
473.35
0.71073
150
C34H42CuN4
570.26
0.71073
150
M
ꢀ
l
(A)
T (K)
Crystal system
Space group
Monoclinic
P21
9.5447(11)
20.320(2)
14.2252(16)
90
101.047(6)
90
2707.9(5)
6
Monoclinic
P21/c
14.580(4)
13.199(4)
20.730(6)
90
99.55(2)
90
3934(2)
4
Monoclinic
P21/n
11.717(4)
11.947(5)
18.090(7)
90
96.84(2)
90
2514.4(15)
4
Monoclinic
P21/c
13.1660(17)
24.591(4)
22.747(3)
90
103.743(9)
90
7153.8(17)
4
Monoclinic
C2/c
19.548(6)
8.689(2)
14.885(5)
90
116.398(14)
90
2264.6(12)
4
Monoclinic
P 21/c
8.3010(8)
32.295(3)
11.4000(10)
90
97.283(5)
90
3031.5(5)
4
ꢀ
a (A)
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
3
ꢀ
V (A )
Z
rcalc (g.cmꢀ3
)
1.461
1.089
1.464
0.807
1.340
0.647
1.180
0.454
1.388
0.691
1.249
0.749
m
(mmꢀ1
)
Crystal size
qmax (ꢁ)
0.24 ꢂ 0.14 ꢂ 0.04
0.10 ꢂ 0.04 ꢂ 0.01
0.28 ꢂ 0.24 ꢂ 0.08
0.60 ꢂ 0.40 ꢂ 0.08
0.18 ꢂ 0.09 ꢂ 0.05
0.15 ꢂ 0.10 ꢂ 0.03
25.68
25.22
25.83
25.25
27.60
25.08
Total data
Unique data
Rint
42737
4962
0.1710
0.0720
0.1395
0.926
30841
3295
0.1582
0.0583
0.0925
0.915
34090
2625
0.1956
0.0908
0.2463
1.010
128460
6115
0.2422
0.0979
0.2132
10229
1927
0.0532
0.0392
0.0865
1.065
45786
3927
0.0768
0.0425
0.0850
1.030
R [I > 2
s
(I)]
Rw
Goodness of fit
0.989
rmin
ꢀ1.140
ꢀ0.481
ꢀ1.049
ꢀ0.534
ꢀ0.390
ꢀ0.379
rmax
1.018
0.435
1.845
0.536
0.445
0.294

176
C.S.B. Gomes et al. / Journal of Organometallic Chemistry 760 (2014) 167e176
ESI-MS: m/z 570 [M þ H]þ (calculated for C34H43N4Cu [M þ H]þ,
570).
References
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mounted on a nylon loop. Crystallographic data for compounds 5,
7, 10e12, and 14 were collected using graphite monochromated
ꢀ
Mo-K
a
radiation (
l
¼ 0.71073 A) on a Bruker AXS-KAPPA APEX II
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idealised positions and allowed to refine riding on the parent
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observed/unique reflections. Crystal 11 showed the presence of
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for 5, 963692 for 7, 963693 for 10, 963694 for 11, 963695 for 12,
and 963696 for 14.
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[17] SAINT Software for the CCD Detector System, Version 7.03, Bruker AXS Inc.,
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[18] G.M. Sheldrick, SADABS, Program for Empirical Absorption Correction, Uni-
versity of Göttingen, Göttingen, 1996.
Acknowledgements
We thank the Fundação para a Ciência e Tecnologia, Portugal, for
financial support (Projects PTDC/EQUeEQU/110313/2009, PTDC/
QUI/65474/2006, PEst-OE/QUI/UI0100/2013, RECI/QEQ-QIN70189/
2012) and for a fellowship to C.S.B.G. (SFRH/BPD/64423/2009).
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Appendix A. Supplementary data
[24] M.N. Burnett, C.K. Johnson, ORTEP-III: Oak Ridge Thermal Ellipsoid Plot Pro-
gram for Crystal Structure Illustration, Oak Ridge National Laboratory, 1996.
Report ORNL-6895.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2013.10.053.