Supramolecular interactions in a copper(II) 4′-(4-bromophenyl)-2, 2′:6′,2″-terpyridine complex

Article abstract of DOI:10.1107/S0108270111004641

The title compound, [4′-(4-bromo-phenyl)-2,2′:6′, 2″-ter-pyri-dine]-chlorido(trifluoro-methane-sulfonato)-copper(II), [Cu(CF₃O₃S)Cl(C₂₁H₁₄BrN ₃)], is a new copper complex containing a polypyridyl-based ligand. The Cu^II centre is five-coordinated in a square-pyramidal manner by one substituted 2,2′:6′,2″-ter-pyridine ligand, one chloride ligand and a coordinated trifluoro-methane-sulfonate anion. The Cu - N bond lengths differ by 0.1 A for the peripheral and central pyridine rings [2.032 (2) (mean) and 1.9345 (15) A, respectively]. The presence of the trifluoro-methane-sulfonate anion coordinated to the metal centre allows Br...F halogen-halogen inter-actions, giving rise to the formation of a dimer about an inversion centre. This work also demonstrates that the rigidity of the ligand allows the formation of other types of nonclassical inter-actions (C - H...Cl and C - H...O), yielding a three-dimensional network.

Full text of DOI:10.1107/S0108270111004641

metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
cott et al., 2007, 2008). As an extension of this study, we are
currently investigating the supramolecular reactivity of the
tridentate pyridyl-substituted ligand tpy to form copper
complexes. Against this background, we present here the
structure of the title copper–tpy complex, (I).
ISSN 0108-2701
Supramolecular interactions in a
copper(II) 40-(4-bromophenyl)-
2,20:60,200-terpyridine complex
Ludwig Chenneberg, Janaina G. Ferreira* and Garry S.
Hanan
´
´
´
Departement de Chimie, Universite de Montreal, CP 6128, Succ. Centre-ville,
´
´
Montreal, Quebec, Canada H3C 3J7
Correspondence e-mail: j.gomes.ferreira@umontreal.ca
Received 18 September 2010
Accepted 7 February 2011
Online 4 March 2011
The CuII centre in (I) is coordinated in a slightly distorted
square-pyramidal environment by three N-atom donors from
the tridentate ligand. The Cl atom occupies the fourth coor-
dination site of the basal plane, with an O atom of the
trifluoromethanesulfonate (triflate) ligand occupying the
apical position. The three N atoms and Cl atom of the basal
plane are nearly coplanar, with the largest deviation from the
The title compound, [40-(4-bromophenyl)-2,20:60,200-terpyri-
dine]chlorido(trifluoromethanesulfonato)copper(II), [Cu(CF3-
O3S)Cl(C21H14BrN3)], is a new copper complex containing a
polypyridyl-based ligand. The CuII centre is five-coordinated
in a square-pyramidal manner by one substituted 2,20:60,200-
terpyridine ligand, one chloride ligand and a coordinated
trifluoromethanesulfonate anion. The Cu—N bond lengths
˚
least-squares plane being 0.0524 (8) A for atom N2. The Cu
˚
atom is displaced by 0.1420 (7) A out of the basal plane.
The Cu—N and Cu—Cl distances (Table 1) are comparable
with those found in the Cambridge Structural Database (CSD,
Version 5.11; Allen, 2002) for 230 other Cu complexes having
the same core as (I). In (I), the Cu—N bond lengths involving
˚
differ by 0.1 A for the peripheral and central pyridine rings
˚
[2.032 (2) (mean) and 1.9345 (15) A, respectively]. The
presence of the trifluoromethanesulfonate anion coordinated
to the metal centre allows Brꢀ ꢀ ꢀF halogen–halogen inter-
actions, giving rise to the formation of a dimer about an
inversion centre. This work also demonstrates that the rigidity
of the ligand allows the formation of other types of
nonclassical interactions (C—Hꢀ ꢀ ꢀCl and C—Hꢀ ꢀ ꢀO), yielding
a three-dimensional network.
˚
the peripheral pyridine rings are about 0.1 A longer than that
of the central pyridine ring. These values compare well with
those found in a copper complex containing a 40-p-tolyl-
2,20:60,200-terpyridine and two chloride ligands [Cu—N-
˚
(peripheral) = 2.052 (3) and 2.035 (3) A, Cu—N(central) =
Comment
Polypyridine ligands, e.g. 2,20:60,200-terpyridine (tpy), have
been the focus of much attention due to their incorporation
into devices with many potential applications, such as
electrochromic materials, anion-recognition devices and solar
photovoltaic cells (Han et al., 2008; Bhaumik et al., 2010). In
particular, several ruthenium(II) complexes based on poly-
pyridine ligands have been prepared and structurally char-
acterized. Heteroleptic complexes are designed to increase the
excited-state lifetime of ruthenium(II) bis(tpy) complexes for
use in such devices (Rajeshwar et al., 2008). In the literature
there are, however, fewer examples of CuII complexes of
substituted tpy ligands and their derivatives (Chen et al., 2010;
McMurtrie & Dance, 2009; Uma et al., 2005; Medlycott et al.,
2008; Wang et al., 2009). Previous work by our group has
described the synthesis of new homoleptic tridentate
complexes containing one central triazine ring that may be
applied to the development of new redox mediators (Medly-
Figure 1
The molecular structure of (I), showing the atom-labelling scheme.
Displacement ellipsoids are drawn at the 50% probability level.
Acta Cryst. (2011). C67, m81–m84
doi:10.1107/S0108270111004641
# 2011 International Union of Crystallography m81

metal-organic compounds
˚
˚
1.940 (3) A and Cu—Cl = 2.228 (1) A, for the four atoms that
form the base of the square-pyramidal coordination around
the metal centre; Wang et al., 2009]. On the other hand, the
CuN6 core of a homoleptic copper complex exhibits an even
greater difference between the peripheral Cu—N and central
˚
Cu—N bond lengths [2.205 (4) versus 1.981 (5) A; Uma et al.,
2005]. The trans N2—Cu1—Cl1 angle in (I) deviates slightly
from linearity, while the cis N1—Cu1—N2 and N2—Cu1—N3
angles have very similar values deviating by about 10ꢁ from
90ꢁ because of the bite constrictions of the ligand.
Fig. 1 shows the molecular structure of (I). The axial posi-
tion of the square-pyramidal CuII coordination environment is
occupied by one O atom of the triflate ligand, with an elon-
Figure 2
A view of the dimer formed by halogen-bonding interactions in (I),
indicated by dotted lines. [Symmetry code: (*) ꢃx + 2, ꢃy + 1, ꢃz + 1.]
˚
gated Cu1—O1 distance of 2.4635 (14) A. In addition, the
triflate ligand extends almost perpendicular to the basal plane
of the complex complex, as shown by the Cl1—Cu1—O1 and
N2—Cu1—O1 angles (Table 1). Another interesting structural
feature of (I) is the dihedral angle of 22.40 (7)ꢁ formed
between the mean plane through the three pyridine rings and
the plane of the bromophenyl group. A similar conformation
was found in the two p-tolylterpyridine complexes mentioned
above (Wang et al., 2009; Uma et al., 2005). The planes of the
three pyridyl rings very slightly tilted with respect to each
other to give dihedral angles between the pairs of rings
containing atoms N1/N2, N2/N3 and N1/N3 of 6.4 (1), 3.7 (1)
and 6.1 (1)ꢁ, respectively. The tilt between the planes of the
central pyridyl and the bromophenyl ring is 24.62 (9)ꢁ.
Figure 3
A view of the dimer formed by the C—Hꢀ ꢀ ꢀCl interactions in (I) (dotted
lines). [Symmetry code: (*) ꢃx, ꢃy + 2, ꢃz + 1.]
Figure 4
A view of the C—Hꢀ ꢀ ꢀO interactions in (I) (dotted lines), showing their influence on the crystal packing and the formation of the supramolecular
1
2
3
2
1
2
1
2
3
2
1
2
assembly. [Symmetry codes: (*) x ꢃ , ꢃy + , z ꢃ ; (**) x ꢃ 1, y, z; (***) x + , ꢃy + , z ꢃ .]
ꢂ
m82 Chenneberg et al.
[Cu(CF3O3S)Cl(C21H14BrN3)]
Acta Cryst. (2011). C67, m81–m84

metal-organic compounds
Table 1
Selected geometric parameters (A, ).
As illustrated in Figs. 2–4, the crystal packing of (I) is
effected by halogen–halogen interactions and weak hydrogen
bonds. In Fig. 2, two molecules are paired by two halogen–
halogen interactions to form a dimer about an inversion
centre. The shortest intermolecular distance involving F and
ꢁ
˚
Cu1—N1
Cu1—N2
Cu1—N3
2.0311 (16)
1.9345 (15)
2.0338 (16)
Cu1—Cl1
Cu1—O1
2.2048 (5)
2.4635 (14)
˚
N1—Cu1—Cl1
N2—Cu1—Cl1
N3—Cu1—Cl1
N1—Cu1—O1
N1—Cu1—N2
98.93 (5)
169.69 (5)
100.24 (5)
95.34 (5)
80.18 (6)
N1—Cu1—N3
N2—Cu1—O1
N2—Cu1—N3
N3—Cu1—O1
Cl1—Cu1—O1
159.51 (6)
90.92 (5)
79.67 (6)
88.61 (5)
99.39 (4)
Br atoms is 3.1482 (14) A, while the predicted sum of the van
˚
der Waals radii for fluorine and bromine is 3.32 A (Bondi,
1964). Thus, this interaction is rather weak. A survey of similar
contacts in the CSD showed 171 reported cases, covering a
˚
range of 2.90–3.40 A with a median (maximum occurrence) at
˚
3.15 A. Furthermore, the dimeric subunits of (I) are linked to
Table 2
Hydrogen-bond geometry (A, ).
each other across centres of inversion between the dimers by
duplex C—Hꢀ ꢀ ꢀCl bonds (Table 2 and Fig. 3) involving the Cl
atom and one of the pyridyl rings of the tpy ligand in an
adjacent molecule (C15—H; Table 2 and Fig. 3). The C—
Hꢀ ꢀ ꢀCl and Brꢀ ꢀ ꢀF interactions serve to link the molecules
into extended chains which run parallel to the [210] direction.
Given that (I) has a nearly planar organic ligand, the crystal
structure might have been expected to present several
aromatic ꢀ–ꢀ interactions, particularly between the tpy ring
systems. However, only one potential interaction is observed,
maybe due the blocking caused by the presence of the triflate
ligand. The bromophenyl rings from two centrosymmetrically-
disposed molecules display a weak ꢀ–ꢀ interaction such that
ꢁ
˚
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
C4—H4ꢀ ꢀ ꢀO1i
0.95
0.95
0.95
0.95
0.95
0.95
0.95
2.53
2.66
2.58
2.60
2.32
2.82
2.66
3.461 (2)
3.556 (2)
3.451 (2)
3.481 (2)
3.183 (2)
3.5696 (19)
3.581 (2)
166
157
152
155
150
137
164
C7—H7ꢀ ꢀ ꢀO1i
C9—H9ꢀ ꢀ ꢀO3ii
C12—H12ꢀ ꢀ ꢀO3ii
C13—H13ꢀ ꢀ ꢀO2iii
C15—H15ꢀ ꢀ ꢀCl1iv
C17—H17ꢀ ꢀ ꢀO1i
1
2
3
2
1
2
1
2
3
1
Symmetry codes: (i) x þ 1; y; z; (ii) x þ ; ꢃy þ ; z þ ; (iii) x ꢃ ; ꢃy þ ; z þ ; (iv)
2
2
ꢃx; ꢃy þ 2; ꢃz þ 1.
Crystal data
˚
the centroids of the rings are separated by 3.7333 (11) A, the
perpendicular distance from the centroid of one ring to the
3
˚
[Cu(CF3O3S)Cl(C21H14BrN3)]
Mr = 636.32
V = 2311.28 (10) A
Z = 4
Cu Kꢂ radiation
ꢃ = 5.78 mmꢃ1
T = 150 K
˚
plane of the other is 3.4034 (8) A and the slippage of the
Monoclinic, P21=n
˚
˚
a = 7.7841 (2) A
b = 16.3043 (4) A
centroids is 1.54 A. Several weak C—Hꢀ ꢀ ꢀO interactions
˚
(Table 2) appear to provide some support to the vertical
alignment of the triflate ligand, and crosslink the above-
mentioned chains to give a three-dimensional network. The
planarity of the tpy ring system clearly facilitates the forma-
tion of these C—Hꢀ ꢀ ꢀO interactions (Fig. 4).
˚
c = 18.2533 (4) A
ꢁ = 93.884 (1)ꢁ
0.10 ꢄ 0.06 ꢄ 0.06 mm
Data collection
Bruker Microstar diffractometer
with a Platinum 135 CCD area
detector
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.452, Tmax = 0.707
47414 measured reflections
4344 independent reflections
4016 reflections with I > 2ꢄ(I)
Rint = 0.039
In summary, the packing of the title copper complex shows
that the presence of the trifluoromethanesulfonate anion plays
an active role in the intermolecular interactions. The close
Brꢀ ꢀ ꢀF contacts in (I) may be stabilizing interactions but they
are apparently not structure determining, since other weak
C—Hꢀ ꢀ ꢀCl and C—Hꢀ ꢀ ꢀO interactions contribute to the
packing pattern.
Refinement
R[F2 > 2ꢄ(F2)] = 0.026
wR(F2) = 0.073
S = 1.07
316 parameters
H-atom parameteꢃrs3 constrained
˚
Áꢅmax = 0.71 e A
ꢃ3
˚
4344 reflections
Áꢅmin = ꢃ0.33 e A
Experimental
˚
H atoms were generated geometrically, with C—H = 0.95 A, and
were included in the refinement in the riding-model approximation,
with Uiso(H) = 1.2Ueq(C).
A round-bottomed flask equipped with a stirring bar was charged
with Cu(CF3SO3)2 (1 equivalent, 0.28 mmol, 101 mg) and bromo-
phenylterpyridine (1 equivalent, 0.28 mmol, 109 mg) in acetonitrile
(10 ml). To increase the solubility of the organic ligand, chloroform
(5 ml) was added to the reaction mixture. The reaction was heated at
358 K for 3 h and then cooled slowly to room temperature under
magnetic stirring. Deep-green crystals formed and were filtered off
and characterized as the title compound (yield 80 mg; 45%). HRMS
(ESI): m/z = 486.93614 (C21H14BrClCuN3 requires 487.25896).
Although the reaction procedure does not involve the chloride
anion, it seems that the presence of copper and air photocatalysed the
decomposition of the chloroform solvent to form the chloride anion,
which was then available to coordinate to the metal centre so as to
give rise to the title compound.
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT
(Bruker, 2009); data reduction: SAINT; program(s) used to solve
structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine
structure: SHELXL97 (Sheldrick, 2008); molecular graphics:
SHELXTL (Sheldrick, 2008); software used to prepare material for
publication: UdMX (Maris, 2004) and XPREP (Bruker, 2008).
The authors are grateful to the Natural Sciences and
Engineering Research Council of Canada and the University
of Montreal for financial assistance, and to the Canadian
Postdoctoral Research Fellowship Programme (PDRF).
ꢂ
Acta Cryst. (2011). C67, m81–m84
Chenneberg et al.
[Cu(CF3O3S)Cl(C21H14BrN3)] m83

metal-organic compounds
Han, F. S., Higuchi, M. & Kurth, D. G. (2008). J. Am. Chem. Soc. 130, 2073–
2081.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: GG3247). Services for accessing these data are
described at the back of the journal.
´
Maris, T. (2004). UdMX. University of Montreal, Canada.
McMurtrie, J. & Dance, I. (2009). CrystEngComm, 11, 1141–1149.
Medlycott, E. A., Hanan, G. S., Abedin, T. S. M. & Thompson, L. K. (2008).
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Medlycott, E. A., Udachin, K. A. & Hanan, G. S. (2007). Dalton Trans. pp.
430–438.
Rajeshwar, K., McConnell, R. & Licht, S. (2008). In Solar Hydrogen
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m84 Chenneberg et al.
[Cu(CF3O3S)Cl(C21H14BrN3)]
Acta Cryst. (2011). C67, m81–m84