Copper(II)-azido complexes constructed from polypyridyl amine ligands

Article abstract of DOI:10.1016/j.poly.2013.04.033

A novel 1-D polymer Cu(II) complex bridged by perchlorate ions and azide ligand with the structural formula [Cu(DPA)(N₃)(μO,O-ClO ₄)]_n (1), {[Cu(L^dpdmen)(μ1,3-N ₃)]ClO₄}_n (2), {[Cu₂(μ-L ^py)(μ-1,1,3-N₃)(μ-1,3-N₃)](ClO ₄)₂}_n (3) and {[Cu₂(L ^T)(μ₂-1,3-N₃)(N₃)(H ₂O)](ClO₄)₂H₂O}_n (4) where DPA = di(2-pyridylmethyl)amine, L^dpdmen = N,N′-bis(2- pyridylmethyl)-N,N′-dimethylethylenediamine and L^py = 2,6-bis[bis(2-pyridylmethyl)aminomethyl]pyridine and L^T = 3,5-bis[bis(2-pyridylmethyl) aminomethyl]toluene were synthesized. The complexes were characterized by spectroscopic techniques (IR and visible) and by single crystal X-ray crystallography. The magnetic properties were also measured for 1-3 at variable temperatures (4.5-300 K). Compound 1 has the copper center in a 4+2 geometry with the equatorial plane formed through the three N-donors of the DPA and an azido group which acting as a monodentate ligand. The 1-D chain is generated via the axial O,O′-bridging perchlorato groups where the intra-chain Cua??Cu distance is 6.9416(16) A?. In complex 2, the Cu center is ligated by the four N-donor atoms of L^dpdmen amine ligand and two N atoms of the EE bridging azido groups in a cis-coordinated asymmetric EE bonding fashion. The intra-chain Cua??Cu distance in this complex is 5.7949(15) A?.

Full text of DOI:10.1016/j.poly.2013.04.033

Polyhedron 59 (2013) 17–22
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Copper(II)–azido complexes constructed from polypyridyl amine ligands
Franz A. Mautner a, , Masayuki Koikawa , Masahiro Mikuriya , Emily V. Harrelson , Salah S. Massoud
⇑
b
c
d
d,
⇑
a
Institut für Physikalische and Theoretische Chemie, Technische Universität Graz, A-8010 Graz, Austria
Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
School of Sciences and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
Department of Chemistry, University of Louisiana at Lafayette, P.O. Box 44370 Lafayette, LA 70504, USA
b
c
d
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel 1-D polymer Cu(II) complex bridged by perchlorate ions and azide ligand with the structural
Received 11 February 2013
Accepted 16 April 2013
Available online 25 April 2013
dpdmen
py
formula [Cu(DPA)(N
3
)(
l
O,O–ClO
4
)]
(L )(
n
(1), {[Cu(L
)(
l
1,3-N
3
)]ClO
4
}
n
(2), {[Cu
(4) where DPA = di(2-pyridyl-
2 3
(l-L )(l-1,1,3-N )
T
(
l
-1,3-N
3
)](ClO
4
)
L
2
}
n
(3) and {[Cu
2
2
l -1,3-N
3
)(N
3
)(H
2
0
O)](ClO
4
)
2
ÅH O}
2
n
dpdmen
0
py
methyl)amine,
= N,N -bis(2-pyridylmethyl)-N,N -dimethylethylenediamine and
L
= 2,6-bis[-
T
bis(2-pyridylmethyl)aminomethyl]pyridine and L = 3,5-bis[bis(2-pyridylmethyl) aminomethyl]toluene
were synthesized. The complexes were characterized by spectroscopic techniques (IR and visible) and
by single crystal X-ray crystallography. The magnetic properties were also measured for 1–3 at variable
temperatures (4.5–300 K). Compound 1 has the copper center in a 4+2 geometry with the equatorial
plane formed through the three N-donors of the DPA and an azido group which acting as a monodentate
ligand. The 1-D chain is generated via the axial O,O -bridging perchlorato groups where the intra-chain
Cuꢀ ꢀ ꢀCu distance is 6.9416(16) Å. In complex 2, the Cu center is ligated by the four N-donor atoms of L
Keywords:
Copper(II) complexes
Polynuclear complexes
Perchlorato bridged
Azido bridged
Crystal structure
Magnetic properties.
0
dpd-
men
amine ligand and two N atoms of the EE bridging azido groups in a cis-coordinated asymmetric EE
bonding fashion. The intra-chain Cuꢀ ꢀ ꢀCu distance in this complex is 5.7949(15) Å.
Ó 2013 Elsevier Ltd. All rights reserved.
1
. Introduction
The azide ion N is a versatile ligand that can assemble and
extent on the nature of the central metal ion; its oxidation state,
the coordination number and geometry of the complex. Nowadays,
it is well established that Cu(II) and Co(II) complexes that are de-
rived from tripod tetradentate amine ligands lead to the isolation
of mononuclear species [1–4] whereas polynuclear species are
mainly produced with tri- and bi-dentate ligands [5,34].
3ꢁ
2+
2+
2+
bridge paramagnetic divalent metal ions such Mn , Co , Ni
2
+
and Cu in a variety of ways. Aside from the fact that the azide
ion can act as a simple terminal monodentate ligand [1–5], it can
also bridge the metal ions in many different coordination bonding
modes which include symmetric and assymetric double bridges
The bridged azide ligand mediates the magnetic interaction be-
tween the paramagnetic metal centers. For example in bridged
l
1
N
1,3-N
3
(end-on-end, EE) [5–13] and
1,14–23],
[23–27]. The versatility of the coordination modes of this small
l
1,1-N
3
(end-on, EO) [5,9–
Cu(II)–azido complexes, symmetric double
strongly antiferromagnetic whereas the corresponding
are strongly ferromagnetic when the Cu–Nazide–Cu angle is less
than 108°. On the other hand asymmetric double 1,3-azido bond-
ing results in weak antiferromagnetic coupling whereas the corre-
sponding 1,1-azido bridges propagate moderately strong ferro- or
anti-ferromagnetic interactions [5,9,10,15,16,19]. The Cu(II)–azido
complexes are considered to be the most investigated systems
compared to other metal(II)-azido compounds because of their di-
verse structures and applications as magnetic materials [35].
Moreover, in biological systems, the Cu–azide chemistry is of con-
siderable interest because copper ions are found in the active sites
of a large number of metalloproteins (hemocyanin, ascorbate oxi-
dase, tyrosinase) and the function of these proteins is inhibited
by the presence of azide ions [36].
l
1,3-azido bonding are
l
1,1,3-N
3
,
l
1,1,1-N
3
,
l
1,1,1,1-N
3
,
l
1,1,2,2-N
3
, and
l
1,1,1,3,3,3
-
l1,1-azido
3
ion and its effectiveness to propagate the magnetic interaction be-
tween the paramagnetic centers made this ligand an attractive tar-
get for extensive studies [1–27]. These bonding modes led to the
formation of diverse polynuclear structures with different
dimensionality (1D, 2D and 3D) and nuclearity (di-, tri-, tetra-,
hexa- and poly-nuclear species) as well as interesting magnetic
properties [5–33]. The coordination mode which can be adopted
by a certain metal ion in the azido complexes depends largely on
the nature of the coordinated co-ligands and the steric environ-
ments imposed onto their skeletons [5]. Also, it depends to some
l
l
⇑
Corresponding authors. Tel.: +43 316 4873 8234; fax: +43 316 4873 8225 (F.A.
Herein we report the structural and characterization of some
Mautner), tel.: +1 337 482 5672; fax: +1 337 482 5676 (S.S. Massoud).
E-mail addresses: mautner@ptc.tu-graz.ac.at (F.A. Mautner), ssmassoud@
louisiana.edu (S.S. Massoud).
Cu(II)–azide complexes that are derived from
a variety of
0
277-5387/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2013.04.033

1
8
F.A. Mautner et al. / Polyhedron 59 (2013) 17–22
polypyridyl amine ligands with different structural skeletons, such
as those illustrated in Chart 1, to see how the ligand environment
might affect the structure and the magnetic properties of these
complexes.
(w), 2949 (m), 2802 (m); pyridyl groups: 1592 (s), 1577 (m),
1474 (m), 1435 (s). H NMR: 8.43 (m, 2H), 7.70 (m, 2H), 7.37
1
(m, 2H), 7.72 (m, 2H), 3.58 (s, 4H), 2.51 (s, 4H), 2.14 (s, 6H);
1
3
C NMR: 159.74 (2-py), 149.06 (6-py), 136.78 (4-py), 123.01
3-py), 122.42 (5-py), 63.95 (N–CH -py), 35.40 (–CH –CH –N),
(
2
2
2
4
3 3
2.94 (CH –N), 40.60 (CH –N).
2
. Experimental
.1. Materials and physical measurements
-Chloromethylpyridine hydrochloride,
2
py
2
.2.2. 2,6-Bis[bis(2-pyridylmethyl)aminomethyl]pyridine (L
mixture of 2,6-bis(bromomethyl)pyridine
0.0 mmol), di(2-pyridylmethyl)amine (4.00 g, 20.0 mmol), tri-
)
A
(2.65 g,
2
2,6-bis(bromo-
1
methyl)pyridine and 3,5-bis(bromomethyl)toluene, were pur-
chased from Aldrich Chem. Comp., di(2-pyridylmethyl)amine
ethylamine (2.02 g, 20.0 mmol) and 80 mL anhydrous THF was
magnetically stirred and gently refluxed under nitrogen gas for
4
vent was removed by rotary evaporator. The resulting red-brown
viscus oil was stirred with 60 mL of 15% NaOH, and then ex-
tracted with CH
0
(
DPA) was obtained from TCI-America, N,N -dimethylethylenedi-
days. The resulting brown mixture was cooled, filtered and sol-
amine from Fluka. All other materials were reagent grade
quality. 3,5-Bis[bis(2-pyridylmethyl)aminomethyl]toluene (L )
was synthesized and characterized according to the published
procedures Ref. [1b]. Infrared spectra were recorded on JASCO
FT/IR-480 plus spectrometer as KBr pellets. Electronic spectra
were recorded using Agilent 8453 HP diode UV–Vis spectropho-
T
2
Cl
2
(3 ꢂ 30 mL). The organic phase was dried
with anhydrous MgSO
4
, filtered and solvent was removed. The li-
gand was purified by column chromatography on alumina using
a mixture of ethyl acetate/MeOH (95/5, v/v) as eluent. Further
purification on the column and evaporating the solvent yielded
orange-brown solid which upon crystallization from CH Cl with
2 2
the aid of charcoal affords off white solid (yield: 2.8 g, 56%).
Characterization: m.p. 109–110 °C, Elemental analysis: Anal. Calc.
for C31
C, 73.87; H, 6.20; N, 19.37%. Selected IR bands (cm ):
1
13
tometer.
H
and
C NMR spectra were obtained at room
temperature on a Varian 400 NMR spectrometer operating at
00 MHz ( H) and 100 MHz ( C). 1H and C NMR chemical
shifts (d) are reported in ppm and were referenced internally
to residual solvent resonances (DMSO-d : d = 2.49, d = 39.4 ppm).
1
13
13
4
6
H
C
H
31
N
7
(501.63 g/mol): C, 74.22; H, 6.23; N, 19.55. Found:
Elemental analyses were carried out by the Atlantic Microlabora-
tory, Norcross, Georgia USA. Magnetic susceptibilities of
compounds were measured on polycrystalline powder at Kwan-
sei Gakuin University and Saga University with a Quantum
Design SQUID MPMS-XL susceptometer working in the range
ꢁ1
m
(C–H):
3
068 (w), 3012 (m), 2915 (w), 2882 (w), 2821 (s); pyridyl
1
groups: 1590 (s), 1577 (m), 1475 (m), 1460 (m), 1437 (s).
NMR: 8.44 (m, 4H), 7.70 (m, 2H), 7.70 (m, 5H), 7.54 (m, 4H),
H
13
7
.40 (s, 2H), 7.19 (m, 4H), 3.73 (m, 8H), 2.48 (s, 4H);
C
4
.5–300 K under external magnetic field of 0.5 T. Diamagnetic
0
0
NMR: 159.48 (2 -py),158.70 (2-py, 6-py), 149.24 (6 -py), 136.93
corrections were estimated from Pascal’s Tables.
Caution: Salts of perchlorate and azide as well as their metal
complexes are potentially explosive and should be handled with
great care and in small quantities.
0
0
0
(
4-py), 122.99 (3 -py, 3-py, 5-py), 122.54 (5 -py), 121.25 (4 -
py), 59.90 (N–CH -py).
2
2
.2.3. Synthesis of [Cu(DPA)(N
Copper(II) perchlorate hexahydrate (0.190 g, 0.5 mmol) and
di(2-pyridylmethyl)amine (0.100 g, 0.5 mmol) were dissolved in
20 ml of H O. The solution was heated for 5 min, followed by
the drop-wise addition of an aqueous solution sodium azide
(0.036 g, 0.55 mmol in 5 mL H O). The violet-blue solution was
3 4 n
)(l-ClO )] (1)
2
2
.2. Synthesis of the compounds
0
0
.2.1. Synthesis of N,N -dimethyl-N,N -bis(2-
2
dpdmen
pyridylmethyl)ethylenediamine (L
)
0
A solution of N,N -dimethylethylenediamine (1.72 g, 20 mmol)
in dry tetrahydrofuran (60 mL) was treated with 2-chloromethyl-
pyridine hydrochloride (6.604 g, 40 mmol) and triethylamine
2
heated on a steam-bath for 10 min, filtered through Celite while
hot and allowed to crystallize at room temperature. After 2 h,
the resulting large crystals of a violet compound which sepa-
rated was collected by filtration, washed with absolute ethanol,
ether and then air dried (overall yield: 192 mg, 95%). Well-
shaped crystals of X-ray quality were obtained from dilute
solutions. Characterization: Elemental analysis: Anal. Calc. for
(
8.093 g, 80 mmol) and the mixture was stirred under reflux
for 18 h. The resulting mixture was cooled to in ice and the tri-
ethylamine hydrobromide was removed by filtration. The filtrate
was then treated with 10 mL 15% NaOH solution and extracted
with CH
anhydrous MgSO
2
Cl
2
(3 ꢂ 40 mL). The combined extracts were dried over
4
. Removal of the solvent with rotary evaporator
C
12
H
13
N
6
CuClO
4
: C, 35.65; H, 3.24; N, 20.79. Found: C, 35.81;
ꢁ
1
yielded dark brown oil which was chromatographed on alumina
and eluted with 95/5 (v/v) mixture of ethyl acetate/MeOH
H, 3.30; N, 21.06%. Selected IR bands (cm ): 2057 (s), 1092
(s), 1637 (vs), 1116 (m) and 1054 (m). Visible spectrum {kmax
,
ꢁ
1
ꢁ1
(R
f
= 0.81). The purified ligand was obtained as yellow viscous
2
nm (emax, M cm )} in H O: 643 (153), in DMSO: 642 nm
ꢁ1
oil (yield: 4.2 g, 79%). Selected IR bands (cm ):
m(C–H) 3064
(212) and in DMF 640 (264).
CH3
CH3
H3C
N
N
N
N
N
N
N
N
HN
N
N
N
N
N
N
N
N
N
N
N
Ldpdmen
Lpy
LT
DPA
dpdmen
0
N,N -bis(2-
Chart 1. Structural relationship between the polypyridyl amine ligands used in this study. Ligand abbreviations: DPA, bis(2-pyridylmethyl)amine; L
0
py
T
pyridylmethyl)-N,N -dimethylethylenediamine; L , 2,6-bis[bis(2-pyridylmethyl)aminomethyl]pyridine, L = 3,5-bis[bis(2-pyridylmethyl)aminomethyl]toluene.

F.A. Mautner et al. / Polyhedron 59 (2013) 17–22
19
dpdmen
2.2.4. Synthesis of [Cu(L
4
)(ClO )]ClO
4
(2a)
absorption corrections were performed using SMART
,
SAINT and the
Copper(II) perchlorate hexahydrate (0.380 g, 1.0 mmol) was
SADABS computer programs [37]. The structures were solved by
direct methods and refined by full-matrix least-squares methods
on F , using the SHELXTL [38] program package. All non-hydrogen
atoms were refined anisotropically. The hydrogen atoms were
located from difference Fourier maps, assigned with isotropic dis-
placement factors and included in the final refinement cycles by
use of geometrical constraints. In case of 2 split occupancies of
0.679(2) and 0.321(2) were applied for disordered oxygen atoms
O(1), O(3), O(4) and O(5), O(6), O(7), respectively.
dpdmen
added to L
2
(0.160, 1.0 mmol) dissolved in H O (20 mL). This
2
solution was heated for 15 min on steam-bath and filtered through
Celite and then allowed to crystallize at room temperature. After
2
weeks, the blue crystals which separated were collected by filtra-
tion, washed with propan-2-ol, followed by ether and air dried
overall yield: 0.340 g, 64%). Characterization: Anal. Calc. for C16-
Cl CuO (523.43 g/mol): C, 36.07; H, 4.16; N, 10.52. Found:
(
H
22
N
4
2
8
ꢁ
1
C, 35.86; H, 4.13; N, 10.09%. Selected IR bands (KBr, cm ):
ꢁ
m
M
(Cl–O) (ClO
4
) at 1098 (vs). UV–Vis spectrum {kmax, nm (
e
max
,
ꢁ
1
ꢁ1
cm )}: in H
2
O: 634 (251).
3
. Results and discussion
dpdmen
2
.2.5. Synthesis of {[Cu(L
)(
l
1,3-N
3
)]ClO
4
}
n
(2)
)(ClO
dpdmen
3.1. Synthesis of the complexes
To an aqueous solution of [Cu(L
.50 mmol in 10 mL H O), NaN
O (5 mL) was added drop-by-drop, during the addition the blue
4 4
)]ClO (0.260 g,
0
H
2
3
(0.046 g, 0.07 mmol) dissolved in
The four green azido complexes [Cu(DPA)(N
3
)(
l
2
-ClO
-1,1,3-N
)(N )(H O)](ClO
4 n
)] (1),
2
dpdmen
py
{
1
[Cu(L
,3-N
ꢀH
the reaction of an aqueous solution containing equimolar amounts
of Cu(ClO O and a methanolic solution of the corresponding
ꢀ6H
amine ligand (DPA, L
of sodium azide. Also, complex 2 was obtained via the reaction of
)(
l
2
-1,3-N
3
)]ClO
(3) and [Cu
4
}
n
(2), {[Cu
2
(
l
-L )(
l
3
3
)(
2
l -
color turns green. The resulting solution was heated on a steam-
bath for 5 min, filtered while hot through Celite and allowed to
crystallize at room temperature. After 2 h, the green crystals which
separated were collected by filtration, washed with propan-2-ol,
followed by ether and then dried in air (overall yield: 0.215 g,
T
3
)](ClO
4
)
2
ꢀnH O}
2
n
2
(L )(l
2
-1,3-N
3
3
2
4
)
2
2
O (4) under investigation were synthesized in high yield by
4
)
2
2
dpdmen py
T
, L , L : Chart1) with an aqueous solution
9
0%). Green needles suitable for X-ray analysis were obtained from
dilute aqueous solutions. Characterization: Elemental analysis:
Anal. Calc. for C16 ClCuO (475.39 g/mol): C, 40.42; H, 4.66;
N, 20.62. Found: C, 40.34; H, 4.64; N, 20.57%. Selected IR bands
dpdmen
[
Cu(L
4 4 3
)(ClO )]ClO with NaN . The synthesized complexes
H
22
N
7
4
were structurally characterized by crystal structure, IR and UV–Vis
spectra. The magnetic susceptibilities of the complexes were inves-
tigated at variable temperatures (4.5–300 K).
ꢁ1
(
cm ): 2060 (s), 2036 (s) 1087 (s). Visible spectrum {kmax, nm
ꢁ1
ꢁ1
(e
2 3
max, M cm )} in H O: 629 (270) and CH CN (640 nm, 274).
py
2
2 3 2 4 2
.2.6. Synthesis of [Cu (L )(N ) ](ClO ) (3)
3.2. IR and electronic spectra of the complexes
The ligand 2,6-bis[bis(2-pyridylmethyl)aminomethyl]pyridine
Lpy) (0.0503 g, 0.100 mmol) dissolved in 5 mL of MeOH was added
to an aqueous solution of Cu(ClO O (0.075 g, 0.200 mmol/
ꢀ6H
0 mL H O). The resulting blue solution was heated on a steam-
bath for 5 min then treated with NaN solution (0.014 g,
O). This solution was heated for another
min, filtered through Celite and allowed to crystallize at room
(
The IR spectra of the azido complexes 1–3 reveal the presence of
4
)
2
2
strong absorption bands at the frequency region 2060–2080 cm
attributed to the asymmetric stretching vibration,
ꢁ1
1
2
m
as(N
3
) of the
ꢁ1
3
azido group. Complexes 1 gave a single band at 2057 cm , as ex-
pected for the monodentate azido group whereas two bands were
observed in complexes 2, 3 and 4 as a result of the existence of the
0
5
.200 mmol/5 mL H
2
temperature. After, 4 days the green crystals which separated were
collected, washed with cold absolute EtOH, ether and air dried
bridging azido groups in two bonding modes (see Section 2). The
ꢁ
Cl–O of the ClO
4
group displayed strong vibration band around
(
overall yield: 0.081 g, 89%). Single crystals were obtained from di-
lute solutions. Characterization: Elemental analysis: Anal. Calc. for
Cu (911.78 g/mol): C, 40.84; H, 3.43; N, 19.97.
ꢁ1
1
090–1150 cm region, and the split of this band into two or three
components in the perchlorato complexes 1 and 4. In this complex,
the split of this band results from the reduction of the symmetry of
C
31
H
31
N13Cl
2
2 8
O
ꢁ1
Found: C, 40.65; H, 3.34; N, 19.84%. Selected IR bands (cm ):
ꢁ
m
(N
UV–Vis spectrum {kmax, nm (
O: 380 (1605), 634 (244, br).
3
) 2079 (vs), 2052 (vs);
m
(Cl–O) (ClO
e
4
) 1120 (vs), 1091 (vs).
ꢁ
1
ꢁ1
Table 1
max per Cu atom, M cm )} in
Crystallographic data and processing parameters.
H
2
Compound
1
2
T
2
.2.7. Synthesis of [Cu
(L )(l
2 2
-1,3-N
3
)(N
3
)(H
2
O)](ClO
4
)
2
ꢀH
2
O (4)
Empirical formula
Formula mass
System
Space group
a (Å)
C
12
H
13ClCuN
6
O
4
C
16 7 4
H22ClCuN O
The complex was isolated as dark bluish-green crystals using a
similar procedure as that described above for complex 3 (overall
yield: 56%). Single crystals were obtained from dilute solutions.
Characterization: Elemental analysis: Anal. Calc. for C33
Cu 10 (960.74 g/mol): C, 41.25; H, 4.20; N, 17.50. Found: C,
1.33; H, 3.90; N, 17.43%. Selected IR bands (cm ):
) 2067 (m), 2054 (vs);
vs), 1089 (vs). UV–Vis spectrum {kmax, nm (saturated solution)}
O: 378, 648 (v br).
404.28
monoclinic
P2
8.6451(17)
13.093(3)
13.765(3)
90
101.70(3)
90
475.41
monoclinic
P2 /c
1
12.262(3)
18.888(4)
8.8122(18)
90
107.45(3)
90
1
/c
40
H N12Cl2-
b (Å)
c (Å)
2
O
ꢁ
1
4
m
(OH) 3449
a
(°)
b (°)
(°)
ꢁ
(
(
H
2
O);
m
(N
3
m
(Cl–O) (ClO
4
) 1145 (m), 1119
c
3
V (Å )
1525.7(6)
4
1947.0(8)
4
in H
2
Z
l
D
(mmꢁ1)
1.639
1.760
1.299
1.622
3
2
.3. X-ray crystal structure analysis
calc (Mg/m )
Crystal size (mm)
0.27 ꢂ 0.23 ꢂ 0.16
0.35 ꢂ 0.30 ꢂ 0.18
hmax (°)
26.37
26.37
The X-ray single-crystal data of the compounds 1 and 2 were
Data collected
11968
14497
collected on a Bruker-AXS SMART CCD diffractometer at 100(2) K.
The crystallographic data, conditions retained for the intensity data
collection and some features of the structure refinements are listed
Unique reflection/Rint
Parameters/restraints
Goodness-of-fit (GOF) on F2
3127/0.0551
251/1
1.101
0.0446/0.1120
1.056/ꢁ0.496
3975/0.0523
264/0
1.031
0.0403/0.0986
0.556/ꢁ0.317
1
R /wR
2
(all data)
in Table 1. The intensities were collected with Mo K
a radiation
3
Residual extrema (e/Å )
(k = 0.71073 Å). Data processing, Lorentz-polarization and

2
0
F.A. Mautner et al. / Polyhedron 59 (2013) 17–22
the ClO group to C2v due to its coordination to the Cu2+ ion or its
4ꢁ
Table 2
Selected bond lengths (Å) and angles (°) for compounds 1 and 2.
involvement in hydrogen bonding (see next section).
The visible spectra of the azido complexes 1–4 and 2a in H
2
O
Compound 1
display a single broad band over the wavelength range 650–630.
Moreover in complex 1, the position of this band did not show
any significant change when the spectrum was measured in DMSO
or DMF. The spectral feature of the complexes is most likely consis-
tent with tetragonally distorted six-coordinate geometry for Cu(II)
complex.
Cu(1)–N(11)
Cu(1)–N(1)
Cu(1)–O(2 )
Cu(1)–O(6)
N(11)–N(12)
1.948(2)
1.988(2)
2.605(2)
2.840(2)
1.198(3)
96.86(9)
164.79(8)
82.64(8)
122.48(19)
153.91(18)
Cu(1)–N(3)
Cu(1)–N(2)
Cu(1)–O(1)
N(12)–N(13)
-
1.981(2)
2.013(2)
2.642(3)
1.155(3)
-
97.98(9)
179.40(9)
82.51(8)
176.6(3)
173.34(9)
0
N(11)–Cu(1)–N(3)
N(3)–Cu(1)–N(1)
N(3)–Cu(1)–N(2)
N(12)–N(11)–Cu(1)
N(11)–Cu(1)–N(1)
N(11)–Cu(1)–N(2)
N(1)–Cu(1)–N(2)
N(13)–N(12)–N(11)
0
0
O(2 )–Cu(1)–O(6)
O(2 )–Cu(1)–O(1)
3
3
.3. Description of the structures
Compound 2
Cu(1)–N(1)
Cu(1)–N(2)
Cu(1)–N(4)
2.008(2)
2.028(2)
2.089(2)
2.606(3)
90.19(9)
89.61(9)
171.52(9)
104.01(9)
77.81(9)
121.99(19)
177.8(3)
Cu(1)–N(11)
Cu(1)–N(3)
N(11)–N(12)
N(12)–N(13)
2.008(2)
2.086(2)
1.194(3)
1.166(3)
162.01(9)
178.17(9)
81.60(9)
98.53(9)
100.74(9)
83.40(8)
-
3 n
.3.1. [Cu(DPA)(N )(ClO4)] (1)
A perspective view of 1 together with the atom numbering
0
Cu(1)–N(13 )
scheme is presented in Fig. 1, and relevant bond parameters are
summarized in Table 2. Cu(1) is six-coordinated in a 4 + 2 fashion
by three N-donor atoms of the DPA ligand, and one N atom of a ter-
minal azido group [Cu(1)–N from 1.948(2) to 2.013(2) Å] in basal
positions; and the trans-axial sites are occupied by oxygen atoms
of perchlorate bridging ligand with semi-coordinative Cu(1)–O
0
N(1)–Cu(1)–N(11)
N(11)–Cu(1)–N(12)
N(11)–Cu(1)–N(3)
N(1)–Cu(1)–N(4)
N(2)–Cu(1)–N(4)
N(12)–N(11)–Cu(1)
N(13)–N(12)–N(11)
N(4)–Cu(1)–N(13 )
N(1)–Cu(1)–N(2)
N(1)–Cu(2)–N(3)
N(2)–Cu(1)–N(3)
N(11)–Cu(1)–N(4)
N(3)–Cu(1)–N(4)
-
bond lengths ranges from 2.605(2) to 2.840(2) Å. The l-O,O-bridg-
Symmetry code: (‘) x, ꢁy + 1/2, z ꢁ 1/2.
ing perchlorate anions connect the Cu polyhedra to a polymeric
chain oriented along the c-axis of the monoclinic unit cell. The in-
tra-chain Cuꢀ ꢀ ꢀCu distance is 6.9416(16) Å, and the shortest inter-
chain Cuꢀ ꢀ ꢀCu separation is 6.8400(16) Å.
dpdmen
3.3.2. {[Cu(L
3 n
)(l1,3-N )](ClO4)} (2)
A perspective view of 2 together with the atom numbering
scheme is presented in Fig. 2, and selected bond parameters are gi-
dpdmen
ven in Table 2. The structure consists of polymeric [Cu(L
N )] ,
3 n
)(-
cationic chains oriented along the c-axis of the
monoclinic unit cell, and perchlorate counter ions. The Cu(1) center
n+
dpdmen
is ligated by four N atoms of the L
amine ligand and two N
atoms of the EE bridging azido group. The Cu(1)–N(L2) bond
distances vary from 2.008(2) to 2.089(2) Å, whereas the cis-coordi-
nated asymmetric EE azido bridge has Cu(1)-N(11) of 2.008(2) and
0
Cu(1)–N(13 ) of 2.606(3) Å. The N(11)–N(12) and N(12)–N(13)
bond distances are 1.198(3) and 1.155(3) Å, respectively. The Cu–
N–N and N–N–N bond angles are 122.48(9)°, 115.02(13)° and
Fig. 2. Perspective view (50% probability ellipsoids) of 2 together with the atom
numbering scheme. Symmetry code: (‘) x, ꢁy + 1/2, z ꢁ 1/2; (‘‘) x, ꢁy + 1/2, z + 1/2.
176.6(3)°, respectively. The intra-chain metalꢀ ꢀ ꢀmetal distance is
5.7949(15) Å, and the shortest inter-chain Cuꢀ ꢀ ꢀCu separation is
8.146(2) Å.
Fig. 1. Perspective view (50% probability ellipsoids) of 1 together with the atom numbering scheme. Symmetry code: (‘) x, ꢁy + 1/2, z ꢁ 1/2; (‘‘) x, ꢁy + 1/2, z + 1/2. Disordered
oxygen atoms with minor occupancy are omitted.

F.A. Mautner et al. / Polyhedron 59 (2013) 17–22
21
3.3.3. Attempts to solve structures of compounds 3 and 4
Full structure determinations of compounds 3 and 4 failed due
to low single crystal quality. However, preliminary structural re-
sults clearly show the polymeric chain core systems of the com-
pounds 3 and 4 (see Supplementary section).
3.4. Magnetic properties
The magnetic data of complex 1 are shown in Fig. 3 in the form
of
ity per Cu unit,
the absolute temperature. At 300, the magnetic moment of 1 is
.88 which is a little bit higher than the spin-only value for cop-
per(II) S = ½ ion. The magnetic moment exhibits a continuous
slight decrease with lowering temperature and reaches 1.70 at
.5 K, which suggests the presence of a weak antiferromagnetic
interaction between the copper(II) ions. Considering the crystal
structure of 1, the magnetic data were analyzed by the Boner–Fish-
er model for an isolated Heisenberg 1D chain [39]:
v
A
and
l
eff versus T plots, where
A
v is the magnetic susceptibil-
leff is the magnetic moment per Cu unit, and T is
1
l
B
l
B
Fig. 4. Temperature dependence of magnetic susceptibilities (red circles) and
effective magnetic moments (blue circles) for complex 2. The solid lines represent
the theoretical curves derived from Eq. (2) with the parameters of g = 2.20 and
4
ꢁ
1
J = 1.68 cm . (Color online.)
2
2
2
2
2
2
vA ¼ ðNg
l
=4kTÞ½ð1:0 þ 5:7979916x þ 16:902653x
vA ¼ ðNg b =kTÞð0:25 þ 0:14995x þ 0:30094x Þ=ð1:0
B
3
4
5
2
3
þ 29:376885x þ 29:832959x þ 14:036918x Þ=ð1:0
þ 2:7979916x þ 7:0086780x þ 8:6538644x
þ 4:5743114x Þꢃ þ N
þ 1:9862x þ 0:68854x þ 6:0626x Þ þ N
a
ð1Þ
2
3
where x = |J|/kT and N is the temperature-independent paramag-
a
ꢁ6
3
ꢁ1
4
2=3
netism, which was set to 60 ꢂ 10 cm mol for each copper(II)
a
ð2Þ
ꢁ1
ion. The best-fitting parameters are g = 2.13 and J = ꢁ0.41 cm
.
where x = J/2kT. The solid line in Fig. 4 shows the calculated curve
The magnetic interaction is negligibly small because of the very
poor overlap of the equatorial magnetic orbital and the axial bridg-
ing perchlorate ion. The magnetic behavior observed in this com-
ꢁ
1
with best-fitting parameters of g = 2.20 and J = 1.68 cm
.
The temperature dependence of magnetic susceptibility of 3
was measured in the temperature range of 2.0–4.5 K under exter-
plex is similar to that found in the bridging
complex {[Cu(MeDPA)( 1,5-dca)]ClO , where MeDEPA = N-meth-
ylbis[2-(2-pyridylethyl)]amine [40].
l1,5-dicyanamido
nal field of 0.5 T. The plots of
v
M
versus T and
leff versus T. are
l
4 n
}
shown in Fig. S2. The eff versus T plot of 3 (2.98
l
l
B
at 300 K) shows
a slight decrease with lowering the temperature over the range
5–300 K followed by an increase on lowering the temperature
from 45 to 10 K, and then decreasing again to 2.53 at 2.0 K.
Based on the structure, the spin-exchange Hamiltonian can be de-
The temperature dependence of magnetic susceptibility of 2
was measured in the temperature range of 4.5–300 K under an
4
l
B
external magnetic field of 0.5 T. Fig. 4 shows the plots of versus
v
A
T and eff versus T. The eff versus T plot of 2 (2.01 l at 300 K)
l
l
B
scribed as H = ꢁ2(2J
1
S
Cu2ꢀSCu1 + J
2
S
Cu1ꢀSCu1) where J
1
= JCu2Cu1 = -
shows a slight decrease with lowering the temperature over the
range 70–300 K and an increase on lowering the temperature
J
Cu2
0
Cu1
0
, J = JCu1Cu1, due to the inversion center symmetry of the
2
0
0
linear tetra-nuclear (Cu2–Cu1–Cu1 –Cu2 ) unit, assuming
. The susceptibility
Eq. (3) as derived from the van Vleck equation [42],
from 70 to 4.5 K, reaching 2.37
B eff
l at 4.5 K. The increase of the l
J
Cu2Cu1
0
= JCu2
0
Cu1 = 0, JCu2Cu2
0
= 0, JCu2Cu1 = JCu2
Cu1
0 0
value indicates a ferromagnetic interaction between two adjacent
Cu(II) centers via the azido groups. The magnetic data were
analyzed by the series expansion (2) for the Heisenberg model
for ferromagnetically coupled S = ½ ions which was derived by
Baker et al. [41].
2
2
vtetð4CuÞ ¼ ð2Ng b =kTÞ½5 expðꢁE
þ expðꢁE =kTÞ þ expðꢁE
þ 3 expðꢁE
ꢂ expðꢁE
þ 4N
was used to fit the experimental data. The best fitted parameters
1
=kTÞ þ expðꢁE
=kTÞꢃ=½5 expðꢁE
=kTÞ þ 3 expðꢁE =kTÞ þ 3
=kTÞ þ expðꢁE
2
=kTÞ
3
4
1
=kTÞ
2
3
4
=kTÞ þ expðꢁE
5
6
=kTÞꢃ
a
ð3Þ
ꢁ1
ꢁ1
are g = 2.28, J
1
= ꢁ0.63 cm , J
2
= 2.8 cm . The J
1
value describes
-1,3) bridging of
is the interaction via the
the magnetic interaction via the end-to-end (
l
2
ꢁ
N
3
being antiferro-magnetic, and J
2
ꢁ
end-on (
l
2
-1,1) of the N
3
being ferro-magnetic. This is in harmony
with the magnetic interaction in most azido-bridged copper(II)
complexes.
4
. Conclusion
We report the synthesis and characterization of four Cu(II)–
azide complexes that derived from a variety of polypyridyl amine
ligands with different structural skeletons, namely [Cu(DPA)(N
3
)
)
dpdmen
py
(l
l
2
-ClO
-1,1,3-N
)(H O)](ClO
4
)]
n
(1), {[Cu(L
)( -1,3-N
ꢀH
)(
)](ClO
O (4). The common structural feature of
l
2
-1,3-N
3
)]ClO
4 n 2
} (2), {[Cu (l-L
T
(
N
3
3
l
2
3
4
)
2
ꢀnH O}
2
n
(3) and [Cu
2 2
(L )(l -1,3-
Fig. 3. Temperature dependence of magnetic susceptibilities (red circles) and
effective magnetic moments (blue circles) for complex 1. The solid lines represent
the theoretical curves derived from Eq. (1) with the parameters of g = 2.13 and
J = ꢁ0.41 cmꢁ . (Color online.)
3
)(N
3
2
4
)
2
2
this series of four complexes is the formation of polymeric chain
1
systems. The magnetic properties of compounds 1–3 exhibit very

2
2
F.A. Mautner et al. / Polyhedron 59 (2013) 17–22
weak magnetic coupling between the Cu2+ centers with antiferro-
´
[15] B. Machura, A. Switlicka, I. Nawrot, J.G. Małecki, K. Michalik, Polyhedron 30
(2011) 2815.
[
ꢁ1
magnetic interaction in complex 1 (J = ꢁ0.41 cm ) ferro-magnetic
16] (a) S. Naiya, C. Biswas, M.G.B. Drew, C.J. Gómez-Gracia, A. Ghost, Inorg. Chim.
Acta 337 (2011) 26;
ꢁ1
interactions in complex 2 (J = 1.68 cm ) and ferro-magnetic and
antiferro-magnetic interactions in complex (J = 2.8 and
3
(b) I. Banerjee, J. Marek, R. Herchel, M. Ali, Polyhedron 29 (2010) 1201.
ꢁ
1
[17] (a) Q.-X. Jia, M.-L. Bonnet, E.-Q. Gao, V. Robert, Eur. J. Inorg. Chem. (2009)
008;
b) W.-W. Sun, X.-B. Qian, C.-Y. Tian, E.-Q. Gao, Inorg. Chim. Acta 362 (2009)
2744;
c) L. Li, D. Liao, Z. Jiang, J.-M. Mouesca, P. Ray, Inorg. Chem. 45 (2006) 7665.
ꢁ
0.63 cm ).
3
(
Acknowledgment
(
[
18] M. Habib, T.K. Karmakar, G. Aromi, J. Ribas-Arino, H.-K. Fun, S.
Chantrapromma, S.K. Chandra, Inorg. Chem. 47 (2008) 4109.
This research was financially supported by the Department of
Chemistry-University of Louisiana at Lafayette.
[19] S. Youngme, T. Chotkhun, N. Chaichit, G.A. van Albada, J. Reedijk, Inorg. Chem.
Commun. 10 (2007) 843.
[
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[
20] Z.G. Gu, Y. Song, J.L. Zuo, X.-Z. You, Inorg. Chem. 46 (2007) 9522.
21] X. Lin, J. Tao, R.-B. Huang, L.-S. Zheng, Inorg. Chem. Commun. 12 (2009) 154.
22] F.A. Mautner, B. Sudy, C. Berger, R.C. Fischer, R. Vicente, Polyhedron 42 (2012)
Appendix A. Supplementary data
9
5.
23] C.-B. Tian, Z.-H. Li, J.-D. Lin, S.-T. Wu, S.-W. Du, P. Lin, Eur. J. Inorg. Chem.
2010) 427.
CCDC 918734, and 918735 contains the supplementary crystal-
lographic data for complexes 1 and 2, respectively. These data can
be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336
[
(
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