Bis{2-[(phenyl imino) eth yl]-1H-pyrrol-1-ido-κ2 N,N′}nickel(II): A supra molecular structure formed by C - H...π hydrogen bonds

Article abstract of DOI:10.1107/S0108270113018118

In the title compound, [Ni(C12H11N2)2], the Ni^II cation lies on an inversion centre and has a square-planar coordination geometry. This transition metal complex is composed of two deprotonated N,N′-bidentate 2-[(phenyl imino) ethyl]-1H-pyr rol-1-ide ligands around a central Ni ^II cation, with the pyrrolide rings and imine groups lying trans to each other. The Ni - N bond lengths range from 1.894(3) to 1.939(2)A and the bite angle is 83.13(11)°. The Ni - N(pyrrolide) bond is substantially shorter than the Ni - N(imino) bond. The planes of the phenyl rings make a dihedral angle of 78.79(9)° with respect to the central NiN4 plane. The mol ecules are linked into simple chains by an intermolecular C - H...π interaction involving a phenyl β-C atom as donor. Intramolecular C - H...π interactions are also present.

Full text of DOI:10.1107/S0108270113018118

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
2012, 2013), in most of which the pyrrole ring is unsubstituted.
To imitate the original structure of the classical late transition
metal catalysts with iminopyridine ligands (Small et al., 1998;
Gibson et al., 1998; Britovsek et al., 2003), we introduced a
methyl side arm on the pyrrole ring (Su, Li et al., 2012; Su, Qin
et al., 2012) to give the iminopyrrolyl analogue (I), and the
corresponding Ni complex, (II). It is notable that all
previously reported syntheses of this kind of iminopyrrole–
NiII complex invariably involve deprotonation of the ligands
(Tenza et al., 2009), whereas we provide here a simpler
synthetic route avoiding that process for this kind of complex.
ISSN 0108-2701
Bis{2-[(phenylimino)ethyl]-1H-pyrrol-
1-ido-j2N,N0}nickel(II): a supra-
molecular structure formed by
C—Hꢀ ꢀ ꢀp hydrogen bonds
Bi-Yun Su,* Jia-Xiang Wang, Xiang Liu and Qian-Ding Li
College of Chemistry and Chemical Engineering, Xi’an ShiYou University, Xi’an,
Shaanxi 710065, People’s Republic of China
Correspondence e-mail: subiyun@xsyu.edu.cn
Received 13 May 2013
Accepted 1 July 2013
In the title compound, [Ni(C12H11N2)2], the NiII cation lies on
an inversion centre and has a square-planar coordination
geometry. This transition metal complex is composed of two
deprotonated N,N0-bidentate 2-[(phenylimino)ethyl]-1H-pyr-
rol-1-ide ligands around a central NiII cation, with the
pyrrolide rings and imine groups lying trans to each other.
˚
2. Experimental
The Ni—N bond lengths range from 1.894 (3) to 1.939 (2) A
and the bite angle is 83.13 (11)ꢁ. The Ni—N(pyrrolide) bond is
substantially shorter than the Ni—N(imino) bond. The planes
of the phenyl rings make a dihedral angle of 78.79 (9)ꢁ with
respect to the central NiN4 plane. The molecules are linked
into simple chains by an intermolecular C—Hꢀ ꢀ ꢀꢀ interaction
involving a phenyl ꢁ-C atom as donor. Intramolecular C—
Hꢀ ꢀ ꢀꢀ interactions are also present.
2.1. Synthesis and crystallization
N-[1-(1H-Pyrrol-2-yl)ethylidene]aniline, (I), was prepared
as described by Su, Li et al. (2012), then dissolved (0.100 g,
0.543 mmol) in methanol (10 ml) in a 50 ml flask and a
methanol solution of NiCl2ꢀ6H2O (0.129 g, 0.543 mmol) was
added slowly dropwise. The mixture was stirred at room
temperature for 3 h. After filtering and washing with hexane,
the solvent was removed and a red powder was obtained.
Selecting chloroform and acetone (1:1 v/v) to dissolve the red
powder (methanol and a small amount of water were poor
solvents), brown crystals of (II) suitable for X-ray diffraction
analysis were obtained using the liquid-phase diffusion
method (yield 69.2%). Analysis calculated for C24H22N4Ni:
C 67.80, H 5.22, N 13.18%; found: C 68.05, H 5.43, N 12.99%.
Keywords: crystal structure; supramolecular chemistry;
pyrrolide ligand.
1. Introduction
Since ꢂ-diimine ligands with bulky aryl substituents form a
series of metal complexes (Johnson et al., 1995; Ittel et al.,
2000) which present outstanding activities for ꢂ-olefin poly-
merization, investigations have focused on the exploration of
nitrogen-based polydentate ligands (Small et al., 1998; Gibson
et al., 1998; Britovsek et al., 2003; Tenza et al., 2009). One of the
explorations aims to promote the synthetic application of
iminopyrrolyl ligands for preparing many kinds of transition
metal complexes (Mashima & Tsurugi, 2005). However,
contrasting with the considerable research reported on
symmetric bis(imino)pyrrole complexes, metal complexes of
ligands containing both an imine and a pyrrolyl group are
uncommon. To the best of our knowledge, only a limited
number of mono(imino)pyrrole compounds have been
reported in the literature (Dawson et al., 2000; Anderson et al.,
MS (EI): m/z 424 (M+). IR (KBr): ꢃ(C N) 1659 cmꢂ1
.
2.2. Refinement
Crystal data, data collection and structure refinement
details are summarized in Table 1. All H atoms were posi-
tioned geometrically and treated using a riding model, with
˚
C—H = 0.93 and 0.96 A for aromatic and methyl H atoms,
respectively, and with Uiso(H) = 1.5Ueq(C) for methyl H atoms
and 1.2Ueq(C) otherwise.
3. Results and discussion
The molecular structure of (II) and the atom-labelling scheme
are shown in Fig. 1, and selected geometric parameters are
´
2006; Carabineiro et al., 2007; Perez-Puente et al., 2008; Imhof,
Acta Cryst. (2013). C69, 851–854
doi:10.1107/S0108270113018118
# 2013 International Union of Crystallography 851

metal-organic compounds
Table 1
Experimental details.
to the NiN4 square plane and are parallel to each other due to
the imposed inversion centre. The five-membered pyrrolide
(py) ring formed by atoms N2/C8–C11 is planar, with a
Crystal data
Chemical formula
Mr
[Ni(C12H11N2)2]
425.17
Monoclinic, P21/c
296
11.379 (2), 15.174 (3), 5.8453 (11)
101.447 (3)
989.2 (3)
2
Mo Kꢂ
1.00
0.35 ꢄ 0.27 ꢄ 0.15
˚
maximum deviation from the plane of 0.004 (3) A for atom
C8. In addition, we note that the Ni—Nimine distance
Crystal system, space group
Temperature (K)
˚
[1.939 (2) A] is substantially longer than the Ni—Npy bond
˚
a, b, c (A)
˚
[1.894 (3) A], due to the anionic nature of the pyrrolide N
ꢁ (ꢁ)
3
˚
V (A )
atom and the steric hindrances of the phenyl-ring substituents.
However, all Ni—N bond lengths in (II) are shorter than the
Z
Radiation type
II
normal values for typical Ni —N bonds (2.07 A; Orpen et al.,
ꢅ (mmꢂ1
Crystal size (mm)
)
˚
1989), particularly the imine Ni—N distances. This may indi-
cate a stronger ꢄ-donor character of atom N1 induced by the
methyl (C12) substituent of the iminic carbon (C7), which may
also give rise to a higher degree of steric congestion around
the NiII cation.
Data collection
Diffractometer
Bruker APEXII CCD area-detector
diffractometer
Multi-scan (SADABS; Bruker, 2008)
0.723, 0.862
4871, 1757, 1272
Absorption correction
Tmin, Tmax
No. of measured, independent and
observed [I > 2ꢄ(I)] reflections
Rint
Comparison of the data for the free ligand, (I) (Su, Li et al.,
2012), and its NiII complex, (II), also highlights some struc-
tural differences. The first feature to note is that the acetyl-
iminopyrrolyl ligand bite angles of (II) (Nimino—Ni—Npy) are
very acute [83.13 (11)ꢁ], and this decreases the N1—C7—C8
and N2—C8—C7 angles in relation to those observed in the
organic ligand precursor (I) [122.82 (16) and 118.71 (16)ꢁ,
respectively]. Also, the angles at the pyrrole N atom (C—
Npy—C) decrease upon coordination, which is compensated
by increases in the angles at the C atoms bound to the pyrrole
N atom. The bond lengths within the pyrrole ring appear to be
significantly affected, and both the C—C and C—N distances,
apart from that opposite the C—C bond of the N atom, appear
to increase. The angle at imino atom N1 (C6—N1—C7)
decreases, but the imine C7 N1 double bond and N1—C6
lengthen upon coordination, indicating that ꢀ-back-donation
from the NiII centre to the imine fragment is relatively strong.
An interesting phenomenon can be observed by comparing
several structures containing various metal complexes of
pyrrole ligands (Anderson et al., 2006; Carabineiro et al., 2007;
0.059
0.597
ꢂ1
˚
(sin ꢆ/ꢇ)max (A
)
Refinement
R[F2 > 2ꢄ(F2)], wR(F2), S
No. of reflections
0.043, 0.088, 1.03
1757
134
0
H-atom parameters constrained
No. of parameters
No. of restraints
H-atom treatment
ꢂ3
˚
Áꢈmax, Áꢈmin (e A
)
0.30, ꢂ0.26
Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97
(Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and
publCIF (Westrip, 2010).
listed in Table 2. Complex (II) crystallizes with the imino
group of the ligand syn to the pyrrolide N atom and has two
inverted N,N0-bidentate chelating pyrrolide ligands. The NiII
cation is located on a crystallographic inversion centre,
tetracoordinated by two imino N atoms and two pyrrolide N
atoms, with the pyrrolide rings and the imine groups trans to
each other (Fig. 1). The sum of the angles around the NiII
centre is 360ꢁ, indicating that this atom is in an essentially
square-planar conformation. The phenyl substituents on the
imine N atoms show a dihedral angle of 78.79 (9)ꢁ with respect
´
Perez-Puente et al., 2008; Imhof, 2012, 2013). The M—N bond
lengths in these examples reveal that the M—Nimino bonds are
˚
ca 0.01–0.05 A longer than the corresponding M—Npy bond
within each metal–bidentate-chelate unit. In addition, a
significant negative correlation is found between the Nimino—
M—Npy angle for the five-membered chelate rings of pyrrole
complexes and the M—Npy bond length. For example, the M—
˚
Npy distance increases from 1.9061 (15) A for [Ni(imino-
Table 2
Selected geometric parameters (A, ).
ꢁ
˚
Ni1—N2
Ni1—N1
N1—C7
N1—C6
N2—C11
1.894 (3)
1.939 (2)
1.317 (4)
1.440 (4)
1.354 (4)
N2—C8
C7—C8
C8—C9
C9—C10
C10—C11
1.383 (4)
1.410 (4)
1.389 (4)
1.378 (4)
1.385 (4)
N2—Ni1—N1
N2—Ni1—N1i
C7—N1—C6
C11—N2—C8
83.13 (11)
96.87 (11)
118.5 (3)
105.4 (3)
N1—C7—C8
N2—C8—C9
N2—C8—C7
N2—C11—C10
114.8 (3)
110.3 (3)
114.8 (3)
110.7 (3)
Figure 1
The molecular structure of (II), showing the atom-numbering scheme.
Displacement ellipsiods are drawn at 30% probability level. Dashed lines
indicate C—Hꢀ ꢀ ꢀꢀ interactions. [Symmetry code: (A) ꢂx + 1, ꢂy + 2, ꢂz.]
N1—C7—C8—N2
ꢂ0.3 (4)
Symmetry code: (i) ꢂx þ 1; ꢂy þ 2; ꢂz.
ꢃ
852 Su et al. [Ni(C12H11N2)2]
Acta Cryst. (2013). C69, 851–854

metal-organic compounds
Figure 2
The unit-cell packing in (II), viewed along b, with the C—Hꢀ ꢀ ꢀꢀ bonding scheme shown as dashed lines. H atoms not participating in C—Hꢀ ꢀ ꢀꢀ
interactions have been omitted for clarity. The largest spheres indicate the centroids of the N2/C8–C11 (Cg1) and C1–C6 (Cg2) rings.
pyrrole)2] [Ar (on imino N atom) = 2,4,6-Me3C6H2; Anderson
˚
et al., 2006] to 1.915 (2) A for [Ni(iminopyrrole)2] (Ar = 2,6-
˚
´
Me2C6H3; Perez-Puente et al., 2008) to 1.9388 (13) A for
[Co(iminopyrrole)2] (Ar = 2,6-diisopropylaniline; Carabineiro
˚
et al., 2007) to 2.0189 (19) A for [Pd(iminopyrrole)2] (Ar =
˚
2,4,6-Me3C6H2; Imhof, 2013) to 2.022 (2) A for [Pd(imino-
C—H bond pointing towards a pyrrolide and phenyl ring C
atom. This corresponds to a type III interaction, according to
the classification of Malone et al. (1997). Furthermore, it has
been recognized that these weak C—Hꢀ ꢀ ꢀꢀ interactions can
play an important role in the conformations of organic mol-
ecules (Umezawa et al., 1999).
pyrrole)2] (Ar = C6H6, Imhof, 2012), while the corresponding
inner bite angle decreases from 83.80 (6) to 83.50 (10) to
82.15 (6) to 80.91 (8) to 80.00 (9)ꢁ across the same series; the
above values are all averages. However, complex (II) does not
conform to the above law. The Ni—Npy bond length is
This work was supported by the Natural Science Basic
Research Plan in Shaanxi Province (grant Nos. 2009JQ2006
and 2010JQ2003), the Scientific Research Plan Project of
Shaanxi Education Department (grant Nos. 12JK0620 and
2010JK784) and the Science and Technology Research
Program of Shaanxi Province (grant No. 2013KJXX-33).
˚
1.894 (3) A. The Nimino—Ni—Npy angle should be greater than
83.80 (6)ꢁ according to the law, but this is not the case, since
the angle is 83.13 (11)ꢁ. This special case may be due to
packing effects.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: LG3114). Services for accessing these data are
described at the back of the journal.
Examination of the structure with PLATON (Spek, 2009)
shows that there is no classical donor (N) present, whereas
there are two C—Hꢀ ꢀ ꢀꢀ interactions (Table 3), thus saturating
the hydrogen-bonding capability of the ꢀ-electron clouds. One
is an intermolecular interaction, with phenyl atom C5 acting as
the donor, while the other is intramolecular (see Figs. 1 and 2),
with pyrrolide atom C11 acting as the donor. The molecules
are linked into extended chains by means of the inter-
molecular C—Hꢀ ꢀ ꢀꢀ interaction. The angles of approach of
the Hꢀ ꢀ ꢀCg vector to the planes of the aromatic rings are
about 77 and 71ꢁ for the pyrrolide and phenyl rings, respec-
tively, and the perpendicular projections of the H atoms onto
References
Anderson, C. E., Batsanov, A. S., Dyer, P. W., Fawcett, J. & Howard, J. A. K.
(2006). Dalton Trans. pp. 5362–5378.
Britovsek, G. J. P., Gibson, V. C., Hoarau, O. D., Spitzmesser, S. K., White,
A. J. P. & Williams, D. J. (2003). Inorg. Chem. 42, 3454–3465.
Bruker (2008). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison,
Wisconsin, USA.
Carabineiro, S. A., Silva, L. C., Gomes, P. T., Pereira, L. C. J., Veiros, L. F.,
Pascu, S. I., Duarte, M. T., Namorado, S. & Henriques, R. T. (2007). Inorg.
Chem. 46, 6880–6890.
Dawson, D. M., Walker, D. A., Thornton-Pett, M. & Bochmann, M. (2000).
J. Chem. Soc. Dalton Trans. 4, 459–466.
˚
the pyrrolide ring planes are 0.604 (2) and 0.867 (7) A,
respectively, from the centroids of the rings. In both inter-
actions, the H atom lies above the centre of the ring, with the
Gibson, V. C., Maddox, P. J., Newton, C., Redshaw, C., Solan, G. A., White,
A. J. P. & Williams, D. J. (1998). Chem. Commun. pp. 1651–1652.
Imhof, W. (2012). Acta Cryst. E68, m1567.
Imhof, W. (2013). Acta Cryst. E69, m96.
Ittel, S. D., Johnson, L. K. & Brookhart, M. (2000). Chem. Rev. 100, 1169–
1203.
Johnson, L. K., Killian, C. M. & Brookhart, M. (1995). J. Am. Chem. Soc. 117,
6414–6415.
Table 3
Hydrogen-bond geometry (A, ).
ꢁ
˚
Malone, J. F., Murray, C. M., Charlton, M. H., Docherty, R. & Lavery, A. J.
(1997). J. Chem. Soc. Faraday Trans. 93, 3429–3436.
Mashima, K. & Tsurugi, H. (2005). J. Organomet. Chem. 690, 4414–4423.
Orpen, A. G., Brammer, L., Allen, F. H., Kennard, O., Watson, D. G. & Taylor,
R. (1989). J. Chem. Soc. Dalton Trans. pp. S1–83.
Cg1 is the centroid of the N2/C8–C11 ring and Cg2 is the centroid of the
C1–C6 ring.
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
C5—H5ꢀ ꢀ ꢀCg1ii
0.93
0.93
2.64
2.62
3.458 (8)
3.384 (9)
147
140
´ ´
Perez-Puente, P., de Jesus, E., Flores, J. C. & Gomez-Sal, P. (2008). J.
Organomet. Chem. 693, 3902–3906.
´
C11—H11ꢀ ꢀ ꢀCg2i
Symmetry codes: (i) ꢂx þ 1; ꢂy þ 2; ꢂz; (ii) ꢂx þ 1; ꢂy þ 2; ꢂz þ 1.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
ꢃ
Acta Cryst. (2013). C69, 851–854
Su et al. [Ni(C12H11N2)2] 853

metal-organic compounds
Small, B. L., Bennett, A. M. A. & Brookhart, M. (1998). J. Am. Chem. Soc. 120,
4049–4050.
Spek, A. L. (2009). Acta Cryst. D65, 148–155.
Su, B.-Y., Li, L., Wang, J.-X. & Li, X.-Y. (2012). Acta Cryst. E68, o2888.
Su, B., Qin, W.-L., Jiao, L. & Wang, J.-X. (2012). Acta Cryst. E68, o3326.
Tenza, K., Hanton, M. J. & Slawin, A. M. Z. (2009). Organometallics, 28, 4852–
4867.
Umezawa, Y., Tsuboyama, S., Takahashi, H., Uzawa, J. & Nishio, M. (1999).
Tetrahedron, 55, 10047–10056.
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.
ꢃ
854 Su et al. [Ni(C12H11N2)2]
Acta Cryst. (2013). C69, 851–854

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