Isolation and properties of a chain of cyano-bridged complex {LCu II(μ-CN)}n with triazenido ligand and a cyano-bridged mixed-valence complex {CuIICuI(μ-CN)3} n

Article abstract of DOI:10.1080/15533174.2012.680147

One reaction of 1-[(2-carboxymethyl) benzene]-3-[2-pyridine] triazene (HL) with CuCl₂·2H₂O, and NaCN gives a chain of cyanobridged complex {LCu^II(μ-CN)}_n 1 and a cyano-bridged mixedvalence complex {Cu^II

Full text of DOI:10.1080/15533174.2012.680147

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Isolation and Properties of a Chain of Cyano-Bridged
Complex {LCuII(µ-CN)}n With Triazenido Ligand and a
Cyano-Bridged Mixed-Valence Complex {CuIICuI(µ-CN)3}n
Wan-Yuan Jian a , Wei Li a , Qi-Ying Lv a , Xin Min a , Yue-Yun Liu a & Shu-Zhong Zhan a
a College of Chemistry & Chemical Engineering , South China University of Technology ,
Guangzhou , P. R. China
Accepted author version posted online: 30 Jul 2012.Published online: 05 Oct 2012.
To cite this article: Wan-Yuan Jian , Wei Li , Qi-Ying Lv , Xin Min , Yue-Yun Liu & Shu-Zhong Zhan (2012) Isolation and
Properties of a Chain of Cyano-Bridged Complex {LCuII(µ-CN)}n With Triazenido Ligand and a Cyano-Bridged Mixed-Valence
Complex {CuIICuI(µ-CN)3}n , Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:10, 1375-1380,
DOI: 10.1080/15533174.2012.680147
To link to this article: http://dx.doi.org/10.1080/15533174.2012.680147
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:1375–1380, 2012
Copyright ꢀ Taylor & Francis Group, LLC
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ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.680147
Isolation and Properties of a Chain of Cyano-Bridged
Complex {LCuII(µ-CN)}n With Triazenido Ligand and a
Cyano-Bridged Mixed-Valence Complex {CuIICuI(µ-CN)3}n
Wan-Yuan Jian, Wei Li, Qi-Ying Lv, Xin Min, Yue-Yun Liu, and Shu-Zhong Zhan
College of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou,
P. R. China
employed CuII cations as a copper source and a triazenido ligand
One reaction of 1-[(2-carboxymethyl) benzene]-3-[2-pyridine]
triazene (HL) with CuCl2·2H2O, and NaCN gives a chain of cyano-
bridged complex {LCuII(µ-CN)}n 1 and a cyano-bridged mixed-
valence complex {CuIICuI(µ-CN)3}n 2, respectively. The X-ray
crystal structures of both complexes have been obtained. Magnetic
studies indicate significant antiferromagnetic coupling between the
copper(II) centers for complex 1, with coupling constants (J) of
(HL = 1-[(2-carboxymethyl) benzene]-3-[2-pyridine] triazene)
to react with NaCN, and isolated two kinds of cyano-bridged
copper complexes such as a chain of cyano-bridged complex
{LCuII(µ-CN)}n 1 and a cyano-bridged mixed-valence complex
{CuIICuI(µ-CN)3}n 2. In this work, we describe an unusual re-
action of NaCN, CuCl2·2H2O, and HL, molecular structures of
complexes 1 and 2, and magnetic property of 1 thereof.
–129.6 cm−1
.
Keywords crystal structures, cyano-bridged complexes, magnetic
property
EXPERIMENTAL
Physical Measurements
Infrared spectra were recorded (in the 4000–400 cm−1) as
KBr disks on a Bruker 1600 FTIR spectrometer (Germany).
Magnetic susceptibility data for powder sample was collected in
the temperature range 2–300 K with a Quantum Design SQUID
Magnetometer MPMS XL-7 (USA). Effective magnetic mo-
INTRODUCTION
In recent years, much research interest has been focused on
crystal engineering of cyano-bridged homocopper and mixed
valence copper (I, II) complexes.[1–4] It is well known that in
aqueous solution copper(II) is easily reduced to copper(I) by
cyanide and that simple C-bonded cyano complexes of copp-
er(II) are unstable with respect to reduction and can not be
isolated easily. Nevertheless, a few cyano-bridged CuII/CuII
complexes have been reported.[5,6] In addition, some cyanob-
ridged CuI/CuII mixed-valence compounds such as [CuII(dien)
CuI(CN)3],[7] [CuII(tn)2CuI(CN)3],[8] [{CuII(CN)2}2CuI(cycla-
ments were calculated by the equation µeff = 2.828(χMT)1/2
where χM is the molar magnetic susceptibility.
,
Synthesis of 1-[(2-carboxymethyl)
benzene]-3-[2-pyridine] triazene (HL)
Methyl anthranilate (10 mmol) in water (5 mL) was mixed
with 1 mol·L−1 HCl 30 mL (30 mmol, 3 equiv) at 0◦C. An aque-
ous solution (15%) of sodium nitrite (15 mmol, 1.5 equiv) was
added dropwise with stirring. Once the amine was dissolved, a
15% solution of 2-aminopyridine in ethanol (10 mmol, 1 equiv)
was added at 0◦C and stirred for 6 h. The reaction mixture
was neutralized with a 15% aqueous of NaCH3CO2 to give a
yellow precipitate. The reaction mixture was filtered, and the
solid was purified by crystallization at –4◦C from 9:1 ethyl ac-
etate/hexanes to obtain yellow crystals. The crystals were col-
lected and dried in vacuo (70%). Anal. Calcd. for C26H26N8O4
(%): C, 60.64; H, 5.05; N, 21.77. Found (%): C, 60.17; H, 5.04;
N, 21.56. 1H NMR (CD2Cl2): δ 8.58 (d, J = 1 Hz, 1H, py), 8.05
(d, J = 2.6 Hz, 1H, Py), 7.96 (d, J = 2.8 Hz, 1H, Py), 7.82 (t,
J = 2.7 Hz, 1H, Py), 7.60 (t, J = 2.7 Hz, 2H, Ar), 7.25 (t, J =
1.7 Hz, 1H, Py), 7.16 (t, J = 2.7 Hz, 1 Hz, Py), 3.97 (s, 3H,
OCH3).
m)],[9] [CuII(pn)2CuI2(CN)4],[10] and [CuII (oxpn)CuI(CN)2][11]
2
have been reported.
In contrast to the rich CuI/CuI Cyanide chemistry, the
CuII/CuII cyanide systems and the mixed-valence CuI/CuII sys-
tems are rare. In order to expand the system of homometallic
cyano-bridged copper complexes involving CuII units, we have
Received 15 September 2011; accepted 1 January 2012.
This work was supported by the Research Foundation for Re-
turned Chinese Scholars Overseas of Chinese Education Ministry (No.
B7050170), the National Science Foundation of China (No. 20971045),
and the Student Research Program (SRP) of South China University of
Technology.
Address correspondence to Shu-Zhong Zhan, College of Chem-
istry & Chemical Engineering, South China University of Technology,
Guangzhou, 510640, P. R. China. E-mail: shzhzhan@scut.edu.cn
1375

1376
W.-Y. JIAN ET AL.
TABLE 2
Synthesis of 1 and 2
Selected bond distances (Å) and angles (◦) for complex 1
To a solution containing ligand (0.515 g, 2 mmol) and tri-
ethylamine (0.20 g, 2 mmol) in ethanol (15 mL), CuCl2·2H2O
(0.32 g, 2 mmol) was added and stirred for 10 min. After ad-
dition of NaCN (0.20 g, 4 mmol) in ethanol (10 mL) to the
previous solution, the mixture was stirred at room temperature
for 1 h. The solution color turned from brown to deep green.
Brown crystals were obtained from the filtrate, which was al-
lowed to stand at room temperature for several days, be collected
by filtration, and dried in vacuo (0.25 g, 78.4%). Anal. Calcd.
for C13H11CuN4O2 1 (%): C, 48.9; H, 3.5; N, 17.6. Found (%):
C, 48.7; H, 3.5; N, 17.6. IR bands (KBr pellets, cm−1): ν = 2135
ν(C≡N). Slow evaporating above filtrate at room temperature,
yellow crystals appeared. The crystals were collected and dried
in vacuo (0.075 g, 24.5%). Anal. Calcd. for C9H15Cu2N4 2 (%):
C, 35.3; H, 4.9; N, 18.3. Found (%): 35.2; H, 4.9; N, 18.3; IR
bands (KBr pellets, cm−1): ν = 2129, 2087 ν(C≡N).
Bond distances
Cu(1)-C(14)
Cu(1)-N(4)
N(1)-N(2)
1.925(5)
2.047(5)
1.281(6)
2.545
Cu(1)-N(5)
Cu(1)-N(1)
N(1)-N(3)
1.943(7)
2.339(4)
1.337(6)
Cu(1)-N(5)
Bond angles
C(14)-Cu(1)-N(5) 128.3(2) C(14)-Cu(1)-N(4) 98.2(2)
N(5)-Cu(1)-N(4)
N(5)-Cu(1)-N(1)
N(2)-N(1)-N(3)
N(3)-N(1)-Cu(1)
C(5)-N(4)-Cu(1)
126.9(2) C(14)-Cu(1)-N(1) 118.3(1)
100.8(1) N(4)-Cu(1)-N(1) 71.7(1)
110.8(4) N(2)-N(1)-Cu(1) 111.8(3)
129.0(3)
118.7(4)
N(1)-N(2)-C(5)
N(4)-C(5)-N(2)
112.7(4)
119.0(4)
N(5)-C(14)-Cu(1) 166.1(5) C(14)-N(5)-Cu(1) 176.6(5)
X-Ray Crystallography
diation (λ = 0.71073 Å) at room temperature. All empiri-
cal absorption corrections were applied by using the SAD-
ABS program (University of Go¨ttingen, Germany, 1996).[12]
Structures are solved using direct methods and the corre-
sponding non-hydrogen atoms were refined anisotropically.
All the hydrogen atoms of the ligands were placed in cal-
culated positions with fixed isotropic thermal parameters and
included in the structure factor calculations in the final stage
of full-matrix least-squares refinement. All calculations were
performed using the SHELXTL system of computer pro-
gram (University of Go¨ttingen, Germany, 1997).[13] Details
of the crystal parameters, data collection, and refinement for
complexes 1 and 2 are listed in Table 1, and selected bond
distances and angles are given in Tables 2 and 3.
Data were collected with a Bruker SMART CCD area de-
tector (Germany) using graphite monochromated Mo-Kα ra-
TABLE 1
Crystallographic data for complexes 1 and 2
Parameter
1
2
Empirical formula
Formula weight
λ (Å)
Crystal system
Space group
a/Å
C13H11CuN4O2
318.80
C9H15Cu2N4
306.33
0.71073
monoclinic
P2(1)/n
12.923(3)
8.9349(18)
13.133(3)
90
101.90(3)
90
1483.8(5)
4
0.71073
monoclinic
p2(1)/n
8.3412(17)
13.511(3)
11.398(2)
90
91.71(3)
90
1283.9(4)
4
b/Å
c/Å
α/◦
TABLE 3
β/◦
Selected bond distances (Å) and angles (◦) for complex 2
γ /◦
V/Å3
Bond distances
Z
Cu(1)-C(8)
Cu(1)-C(7)
Cu(1)-Cu(1)
Cu(2)-N(2)
C(7)-N(2)
C(8)-N(4)
N(3)-C(9)
1.925(7)
2.018(7)
2.5175(17)
1.918(6)
1.140(9)
1.160(9)
1.131(9)
Cu(1)-C(9)
Cu(1a)-C(7)
Cu(2)-N(3)
Cu(2)-N(4)
C(7)-Cu(1)
C(9)-N(3)
1.959(6)
2.211(7)
1.917(8)
1.956(6)
2.018(7)
1.131(9)
1.160(9)
Dc/Mg m−3
F(000)
1.427
1.585
620
3.02 to 27.48
648
θ range for data
collection
Reflections
collected/unique
Data/restraints/
parameters
Goodness-of-fit on
F2
3.04 to 27.48o
14149/3397
3397/0/200
1.065
2885/1822
2885/0/127
1.145
N(4)-C(8)
Bond angles
108.8(3) C(8)-Cu(1)-C(7) 118.7(3)
109.1(3) C(8)-Cu(1)-Cu(1a) 131.3(2)
C(8)-Cu(1)-C(9)
C(9)-Cu(1)-C(7)
C(9)-Cu(1)-Cu(1a) 118.3(2) C(7)-Cu(1)-Cu(1a) 57.1(2)
Final R indices
[I > 2sigma(I)]
R indices (all data)
R1 = 0.0587
wR2 = 0.1448
R1 = 0.1300
wR2 = 0.2127
R1 = 0.0462
N(3)-Cu(2)-N(2)
128.4(3)
109.8(3)
N(3)-Cu(2)-N(4) 121.5(3)
N(2)-C(7)-Cu(1) 151.3(6)
wR2 = 0.0997 N(2)-Cu(2)-N(4)
R1 = 0.0958
N(2)-C(7)-Cu(1a)
135.5(6) Cu(1)-C(7)-Cu(1) 72.9(2)
173.0(7) C(7)-Cu(1)-C(7) 107.1(2)
wR2 = 0.1609 C(7)-N(2)-Cu(2)

CYANO-BRIDGED COMPLEXES
1377
SCH. 1. Schematic representation of the synthesis of HL and complexes 1 and 2.
RESULTS AND DISCUSSION
Crystal Structure of 2
The symmetric units of 2 are illustrated in Figures 3 and
4. Mixed-valence complex 2 is completed by two copper
atoms, three cyanides, and one Et3N molecule. Cu(1) is four-
coordinated by four cyano-C atoms, and the Cu-C distances fall
in range 1.925(7) to 2.018(7) Å. Cu(2) is three-coordinated by
Synthesis and General Properties
The ligand 1-[(2-carboxymethyl) benzene]-3-[2-pyridine]
triazene (HL) is synthesized by the reaction of methyl anthrani-
late, sodium nitrite, and 2-aminopyridine (Scheme 1; see also
Figure S1NMR of HL).
In the presence of Et3N, NaCN reacts with CuCl2·2H2O
and HL in C2H5OH solvent to form an unexpected chain of
cyano-bridged complex {LCuII(µ-CN)}n 1 and a cyano-bridged
CuII/CuI complex 2. The infrared spectrum of 1 shows one
ν(C≡N) stretching at 2135 cm−1 at higher energies than free
CN− (2080 cm−1), assigning to the cyano-bridged mode of
1 (Figure S2). Complex 2 exhibits two bands at 2129, and
2087 cm−1, which are assigned to the bridged CN and the ter-
minal CN groups, respectively (Figure S3).
Crystal Structure of Complex 1
The unit of 1 is shown in Figure 1, the copper atom is four
coordinated with two nitrogen atoms and two cyanides. The
Cu-C distance is 1.925(5) Å, and the Cu-N bond lengths fall
in the range 2.047(5)–2.545 Å. An infinite chain {-LCuII-CN-
LCuII-CN-} is built by cyano-bridges, and two copper centers
are separated by 3.217 Å (Figure 2).
FIG. 1. The crystal structure of units of 1 (color figure available online).

1378
W.-Y. JIAN ET AL.
FIG. 2. Cell packing of 1 (color figure available online).
three nitrogen atoms of cyanide groups, and the average bond C(7), Cu(1a), C(7a) is planar with the torsion angle C(7)-Cu(1)-
lengths between Cu and N is 1.330 Å.
C(7a)-Cu(1a) of 0.0◦. Three Cu2(CN)2 dimers are linked to
The interesting feature is that Cu(1) is linked with Cu(1a) via Cu(2) via cyanides, the three-coordinated cyanide-Cu-cyanide
metal-metal bond and two cyanides. The distance of Cu(1) and angles are 109.8(3), 121.5(3), and 128.4(3), respectively. The
Cu(1a) is 2.5175 Å, and the distances between Cu(1) and C are resulting sheets are tiled from alternating Cu2(CN)2 dimers and
2.018(7) and 2.211(7) Å, respectively. The Cu(1)-C(7)-Cu(1a) three-coordinated centers, Cu(2) (Figure 5).
bond angle is 72.9(2), and the C(7)-Cu(1)-C(7a) bond angle
is 107.1(2)◦. The bridging pane (Cu2(CN)2) containing Cu(1),
Magnetic Behavior of 1
The magnetic behavior of complex 1 is shown in Figure 6
in the form of χM versus T. 1 is characterized by having low
room-temperature magnetic moment [µeff = 0.32 µB (300 K)],
indicating significant antiferromagnetic coupling between the
copper(II) centers. The data are fitted on the basis of the Heisen-
berg model H = –2JS1·S2. The molar magnetic susceptibility
for Cu(II)-Cu(II) units is expressed as in Eq. 1.[14]
ꢀ
ꢁ
ꢂꢃ−1
2Nβ2g2
J
Nβ2g2
χM
=
3+exp
−
(1−ρ)+
ρ +2Nα
kT
kT
2kT
[1]
Least-squares fitting of the experimental data led to J =
–192.6 cm−1, Nα = 1.1 × 10−3 cm3mol−1, and ρ = 0.1.
As a consequence, there was a strong antiferromagnetic ex-
change interaction between copper(II) ions mediated by cyano-
bridges.
FIG. 3. Illustration showing the coordination sphere of CuII and CuI of 2 (color
figure available online).

CYANO-BRIDGED COMPLEXES
1379
FIG. 4. The ORTEP view of 2 (color figure available online).
FIG. 5. Cell packing of 2 (color figure available online).
FIG. 6. Temperature dependence of χM at 3000 Oe for 1.

1380
W.-Y. JIAN ET AL.
6. Duggen, D.M.; Hendrickson, D.N. X-ray structural characteri-
SUPPLEMENTARY MATERIALS
zation of an outer-sphere copper(II) dimer, dicyanobis(2,2ꢀ,2ꢀꢀ-
triaminotriethylamine)dicopper(II) tetraphenylborate. Hydrogen-bonding
between two trigonal-bipyramidal copper cations. Inorg. Chem. 1974, 13,
1911–1916.
7. Huang, S.F.; Wei, H.H.; Wang, Y. A new cyano-bridged one-dimensional
polymeric mixed-valence CuII/CuI complex formed from reduction of a
binuclear CuII complex with sodium cyanide. Polyhedron 1997, 16, 1747.
8. Pretsch, T.; Ostmann, J.; Donner, C.; Nahorska, M.; Mrozinski, J.; Hartl,
H. Synthesis, crystal structure, magnetic properties and electrochemical
behaviour of the mixed valence compound> [CuI(CN)3CuII(C3H10N2)2 ].
Inorg. Chim. Acta 2005, 358, 2558–2564.
CCDC 758981 and 772978 contain the supplementary crys-
tallographic data for this paper. The data can be obtained free
of charge from the Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data request/cif.
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