A hexanuclear Ni(II) complex of 1-[(2-carboxymethyl)benzene]-3-[2-pyridine] triazene

Article abstract of DOI:10.1016/j.inoche.2011.03.030

A reaction of 1-[(2-carboxymethyl)benzene]-3-[2-pyridine]triazene (HL) and Ni(Ac)₂·4H₂O yields crystals of {Ni ₆L₂L′₂(μ₃-OH) ₂(CH₃O)₂(Ac)₂(H₂O) ₄} 1 (L′ = 1-[(2-carboxyl)benzene]-3-[2-pyridine]triazene ion), which has been characterized by single-crystal and powder X-ray diffraction, vibrational spectroscopy, thermogravimetric (TG) analysis, as well as variable-temperature magnetic susceptibility. Complex 1 has a remarkable structure with unusual diversity of bridging groups including triazenide molecules, OH^- groups and -OCH₃ groups. The magnetic susceptibility study reveals antiferromagnetic interaction between nickel(II) ions in the polynuclear complex.

Full text of DOI:10.1016/j.inoche.2011.03.030

Inorganic Chemistry Communications 14 (2011) 916–919
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Inorganic Chemistry Communications
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A hexanuclear Ni(II) complex of
1-[(2-carboxymethyl)benzene]-3-[2-pyridine] triazene
⁎
⁎
Wei Li, Jin-Ye Chen, Wei-Quan Xu, Er-Xuan He, Shu-Zhong Zhan , De-Rong Cao
College of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou, 510640, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A reaction of 1-[(2-carboxymethyl)benzene]-3-[2-pyridine]triazene (HL) and Ni(Ac)2⋅4H2O yields crystals
of {Ni6L2L′2(μ3-OH)2(CH3O)2(Ac)2(H2O)4} (L′=1-[(2-carboxyl)benzene]-3-[2-pyridine]triazene ion),
Received 20 November 2010
Accepted 2 March 2011
Available online 17 March 2011
1
which has been characterized by single-crystal and powder X-ray diffraction, vibrational spectroscopy,
thermogravimetric (TG) analysis, as well as variable-temperature magnetic susceptibility. Complex 1 has a
remarkable structure with unusual diversity of bridging groups including triazenide molecules, OH− groups
and –OCH3 groups. The magnetic susceptibility study reveals antiferromagnetic interaction between nickel(II)
ions in the polynuclear complex.
Keywords:
Triazene
Polynuclear nickel complex
Crystal structure
Magnetic property
© 2011 Elsevier B.V. All rights reserved.
The study of metal complexes containing triazenido [RN=N–NR’]−
ligands has increased greatly during the past two decades, as these
compounds have remarkable bridging ability (Scheme 1a) to afford
multinuclear complexes possessing potentially useful for the develop-
ment of new materials and catalysts [1–6]. Although complexes
with 1,3-(aryl) triazines are well known [7–12], relatively few other
triazenide complexes have been developed [13,14]. With this mind,
we extended our interests to the design, synthesis and reactivity
with transition metals of new triazenide ligands (Scheme 1b), which
can delocalize electron density through strongly donate π electron
density to the metal atoms and control the organization of metal
complexes [15].
As shown in Fig. 1, the metallic core comprises six nickel centres,
all in distorted octahedral geometries, which can be described as four
edge-sharing [Ni]3 triangular building blocks. The structure consists
of six nickel centers bridged by two deprotonated L– ligands, two new
deprotonated L′2– ligands, two OH− groups, two –OCH3 groups, two
acetate ions and four H2O molecules [21].
The structure of 1 can be described as two connected trimers
(Ni(1)–Ni(2)–Ni(3) and Ni(1)#–Ni(2)#–Ni(3)#). Ni(1) is hexa-
coordinated by two nitrogen atoms of L− ligand, four oxygen atoms
from H2O, L′2−, OH− group and –OCH3 group, respectively. Ni(1)–N
lengths are 2.038(6) and 2.086(6) Å, which are compared to those
found in hexa-coordinated Ni(II) complexes [22]. Ni(1)–O distances
fall in the range 2.030(4) to 2.148(4) Å, which are similar to those
observed in other nickel(II) complexes [23,24]. Ni(2) is hexa-
coordinated by three nitrogen atoms from two different triazenide
ligands (L− and L′2−) and three oxygen atoms from H2O, acetate
ion, and OH− group. Ni(2)–N lengths fall in the range 2.048(5) to
2.125(5) Å, and Ni2–O distances fall in the range 2.032(4) to 2.091
(4) Å. Similar to Ni(1) and Ni(2), Ni(3) is also coordinate, being
1-[(2-carboxymethyl)benzene]-3-[2-pyridine]triazene (HL) was
synthesized by the reaction of methyl anthranilate, sodium nitrite,
and 2-aminopyridine (supporting information, Figure S1. 1H NMR
spectrum of HL) [16,17]. 1H resonances were found in the range
of 8.6–7.1 ppm for the aromatic protons, 3.97 ppm for the methyl
group. The reaction of HL and Ni(Ac)2⋅4H2O gave a hexanuclear
nickel(II) complex {Ni6L2L′2(μ3-OH)2(CH3O)2(Ac)2(H2O)4}
1
[Scheme 2 and 18].
bound to one nitrogen atom of L′2− and five oxygen atoms from L′2−
,
The IR spectrum of complex 1 exhibits three absorptions at 1336,
1244 and 1145 cm−1, which are assigned to the NNN asymmetric
stretching, symmetric stretching and bending modes, respectively
[19]. Band at 1559 cm− 1 can be assigned to the bridging acetate
ions [20] (supporting information, Figure S2. IR spectrum of
complex 1).
acetate ion, OH− group and –OCH3 groups, respectively. Ni(3)–N
lengths are 2.038(6) and 2.086(6) Å, and Ni(3)–O distances fall in
the range 2.044(4) to 2.074(4) Å.
Ni(1) and Ni(2) are linked by a μ3-OH with a Ni(1)–O(5)–Ni(2)
bond angle of 120.02(19)o. Ni(1) and Ni(3) are linked by a μ3-OH and
an O–Me oxygen with Ni(1)···Ni(3) distance of 3.1004(13) Å. The
bridging pane containing Ni(1), O(5), Ni(3), O(8) is almost planar
with the torsion angle O(5)–Ni(3)–O(8)–Ni(1) of −179.08(14)o.
Ni(2) and Ni(3) are linked by a μ3-OH and a carboxyl bridges with
Ni(2)···Ni(3) distance of 3.2107(11) Å. Three nickel atoms are linked
⁎
Corresponding authors. Fax: +86 20 87112053.
E-mail address: shzhzhan@scut.edu.cn (S.-Z. Zhan).
1387-7003/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2011.03.030

W. Li et al. / Inorganic Chemistry Communications 14 (2011) 916–919
917
R
R"
R'
R'
N
and Ni(1)–O(5)–Ni(3)#–O(8)) both are almost planar with the
torsion angles 0.55 and 0.9o, respectively.
N
N
N
N
N
H
N
Power X-ray analysis of polycrystalline samples of the solids
obtained shows the identity of the complex 1 (supporting informa-
tion, Figure S3. X-ray powder diffraction patterns for complex 1).
A simultaneous TG and DSC analysis of complex 1 were carried
out in N2. And the corresponding curves are presented in Figure S4,
the first mass loss is the two OH− and the four H2O group between
50 and 130°C (exp. 7%; calcd. 6.5%) with an endothermic peak
at 50°C. Then the mass loss could be the two Ac− molecules (exp.
8%; calcd. 7.2%) and there is a small endothermic peak at 180°C.
The main mass loss takes place between 200 and 530°C, and may
be the organic ligand (exp. 58%; calcd. 54.2%) with a strong exo-
thermic peak at 465°C. Afterwards the remaining mass stays almost
constant with the final residue corresponding to NiO (exp. 26%;
calcd. 27.0%).
M
M
b
a
Scheme 1. Generic triazenido binding modes and new triazenes.
by a μ3-OH group with Ni–O–Ni angles of 120.02(19), 103.93(19),
and 99.11(16)o. Connection of two [Ni]3 units by four oxygen atoms
from L′2− ligands and –OCH3 groups forms a hexanuclear nickel
complex 1 with two inter-penetrating pseudo-cube of [Ni3O4] (Fig. 2).
The bridging pane (Ni(3)–O(8)–Ni(3)#–O(8)#) is planar with the
torsion angle 0.0o, and the bridging panes (N(1)–O(3)–Ni(3)–O(8)
Scheme 2. Schematic representation of the synthesis of complex 1.
Fig. 1. ORTEP plot of complex 1. Selected bond distances (Å) and angles (o) are as follows: Cu(1)–O(1), 1.896(10); Cu(1)–O(7), 1.931(13); Cu(1)–O(19), 1.965(9); Cu(1)–N(6), 1.988(13);
Cu(1)–O(2), 2.377(12); Cu(1)–Cu(4), 3.044(2); Cu(2)–O(2), 1.937(10); Cu(2)–O(20), 1.955(12); Cu(2)–O(4), 1.972(9); Cu(2)–N(2), 1.994(13); Cu(2)–O(1), 2.376(11); Cu(3)–O(5),
1.909(10); Cu(3)–O(1), 1.922(13); Cu(3)–N(4), 1.968(16); Cu(3)–N(5), 2.017(11); Cu(3)–O(20), 2.477(12); Cu(4)–O(2), 1.923(13); Cu(4)–N(3), 1.948(16); Cu(4)–O(8), 1.951(10);
Cu(4)–N(1), 2.027(10); Cu(1)–O(1)–Cu(3), 123.0(5); Cu(4)–O(2)–Cu(2), 120.4(5).

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W. Li et al. / Inorganic Chemistry Communications 14 (2011) 916–919
and the Student Research Program (SRP) of South China University of
Technology.
Appendix A. Supplementary material
CCDC 763699 contains the supplementary crystallographic data
for complex 1. The data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/j.inoche.2011.03.030.
References
[1] A.G.M. Barrett, M.R. Crimmin, M.S. Hill, P.B. Hitchcock, G. Kociok-Kohn, P.A.
Procopiou, Triazenide complexes of the heavier alkaline earths: synthesis,
characterization, and suitability for hydroamination catalysis, Inorg. Chem. 47
(2008) 7366–7376.
[2] G. Albertin, S. Antoniutti, M. Bedin, J. Castro, S. Garcia-Fontan, Synthesis and
characterization of triazenide and triazene complexes of ruthenium and osmium,
Inorg. Chem. 45 (2006) 3816–3825.
[3] C.J. Adams, R.A. Baber, N.O. Connelly, P. Hardeng, O.D. Hayward, M. Kandiah,
A.G. Orpen, Iodination of triazenide-bridged rhodium and iridium com-
plexes: oxidative addition vs. one-electron oxidation, Dalton Trans. (2007)
1325–1333.
Fig. 2. Connection of [Ni6O6].
[4] C. Tejel, M.A. Ciriano, G. Rios-Moreno, I.T. Dobrinovitch, F.J. Lahoz, L.A. Oro, M. Parra-
Hake, Crescent-shaped rhodium(I) complexes with bis(o-carboxymethylphenyl)
triazenide, Inorg. Chem. 43 (2004) 4719–4726.
[5] N.G. Connelly, O.D. Hayward, P. Klangsinsirikul, A.G. Orpen, Novel dicarbonyl and
carbonylnitrosyl tris(μ-triazenide) dirhodium complexes, Dalton Trans. (2002)
305–306.
[6] D.B. Kimball, M.M. Haley, Triazenes: a versatile tool in organic synthesis, Angew.
Chem. Int. Ed. 41 (2002) 3338–3351.
[7] P. Gantzel, P.J. Walsh, Synthesis and crystal structures of lithium and potassium
triazenide complexes, Inorg. Chem. 37 (1998) 3450–3451.
[8] S. Westhusin, P. Gantzel, P.J. Walsh, Synthesis and crystal structures of magnesium
and calcium triazenide complexes, Inorg. Chem. 37 (1998) 5956–5959.
[9] J.J. Nuricumbo-Escobar, C. Campos-Alvarado, G. Ríos-Moreno, D. Morales-Morales,
P.J. Walsh, M. Parra-Hake, Binuclear palladium(I) and palladium(II) complexes
of ortho-functionalized 1,3-bis(aryl)triazenido ligands, Inorg. Chem. 46 (2007)
6182–6189.
[10] M.K. Rofouei, M. Hematyar, V. Ghoulipour, J.A. Gharamaleki, Syntheses, structures,
thermal behavior and solution studies of two types of Hg(II) complexes with
[1,3-di(2-methoxy)benzene]triazene, Inorg. Chim. Acta 362 (2009) 3777–3784.
[11] M. Horner, G.M. de Oliveira, V.F. Giglio, L. do Canto Visentin, F. Broch, J. Beck,
Bidimensional self-assembling of [HgII(RPhNNNPhR′)2] (R=acetyl, R′=F)
through metal-η4-arene π-interactions and non classical C–H…O bonding:
Synthesis and X-ray characterization of a bis diaryl asymmetric-substituted
triazenide complex polymer of Hg(II), Inorg. Chim. Acta 359 (2006)
2309–2313.
Fig. 3 shows the temperature dependence of χMT and χ−M1 values for
complex 1. The χMT value at room temperature is 6.98 cm3K mol−1
,
close to the expected value of 7.26 cm3K mol−1 for six non-interacting
S=1 centers assuming g=2.20. The χMT value gradually decreases
upon decreasing temperature. Further cooling decreases the χMT value
to 1.78 cm3K mol−1 at 2 K. The 1/χM versus T plot (300–26 K) obeys the
Curie-Weisslaw witha nativeWeiss constant of θ=−39.1 K. The native
θ suggest a dominant antiferromagnetic exchange among the six NiII
ions through oxygen bridges.
The present study shows that 1-[(2-carboxymethyl)benzene]-3-[2-
pyridine]triazene can chelate and bridge metal centers in special frame
to give a polynuclear nickel complex 1. Currently we are exploring
the reactivity with other metals.
Acknowledgement
This work was supported by the Research Foundation for Returned
Chinese Scholars Overseas of Chinese Education Ministry (No.
B7050170), the National Science Foundation of China (No. 20971045),
[12] M. Horner, G.M. de Oliveira, E.G. Koehler, L. do CantoVisentin, Polymeric
bidimensional self-assembling of [HgII(RC6H4NNNC6H4R)2Py] (R=m-acetyl)
through metal-η2, η2-arene π-interactions and non classical C–H#O bonding:
Synthesis and X-ray characterization of
a bis diaryl symmetric-substituted
triazenide complex of Hg(II), J. Organomet. Chem. 691 (2006) 1311–1314.
[13] J.E. O'Connor, G.A. Janusonis, E.R. Corey, 1,3-dimethyltriazenocopper(I), Chem.
Commun. (1968) 445–446.
[14] W.J. Lei, X.W. Tan, L.J. Han, S.Z. Zhan, B.T. Li, Design, synthesis and properties
of a trinuclear copper(I) cluster with a triazenide ligand, Inorg. Chem. Commun.
13 (2010) 1325–1328.
45
40
35
[15] J. Barker, M. Kilner, The coordination chemistry of the amidine ligand, Coord.
Chem. Rev. 133 (1994) 219–300.
[16] G. Vernin, C. Siv, J. Metzger, C. Parkanyi, Synthesis of 1,3-diaryltriazenes and their
derivatives by aprotic decomposition of arylamines, Synthesis (1977) 691–693.
[17] W. Li, X.W. Tan, W.J. Lei, S.Z. Zhan, D.R. Cao, Synthesis, structure and magnetic
properties of a tetranuclear copper(II) complex with a triazenido ligand, Transition
Met. Chem. 35 (2010) 835–839.
[18] Synthesis of Ni6L2L′2(μ3-OH)2(CH3O)2(Ac)2(H2O)4 (1): To a solution, containing
ligand(HL) (0.25 g, 1 mmol)and triethylamine (0.10g, 1 mmol) in dichloromethane/
methanol (30 ml, 1:1), Ni(CH3CO2)2⋅4H2O (0.373 g, 1.5 mmol) was added and
the mixture was stirred for 20 min. The solution was allowed to slowly evaporate
to brown crystals, which were collected and dried in vacuo (0.21 g, 51%).
Calcd for C56H60N16Ni6O20: C, 41.24; H, 3.68; N, 13.75. Found: C, 42.07; H, 3.59; N,
14.11.
30
7
25
6
5
20
4
3
15
2
10
1
0
50 100 150 200 250 300
T (K)
[19] M. Venter, I. Haiduc, L. David, O. Cozar, IR and ESR studies on new bis-triazenido
cobalt(II) and copper(II) complexes, J. Mol. Struct. 408/409 (1997) 483–486.
[20] A. Roth, J. Becher, C. Herrmann, H. Go1rls, G. Vaughan, M. Reiher, D. Klemm, W.
Plass, Trinuclear Copper(II) Complexes Derived from Schiff-Base Ligands Based on
a 6-Amino-6-deoxyglucopyranoside: Structural and Magnetic Characterization,
Inorg. Chem. 45 (2006) 10066–10076.
5
0
100
200
T (K)
300
Fig. 3. Plots of the χMT vs T (inset) and χ−M 1 vs T for complex 1 at 2000 Oe.

W. Li et al. / Inorganic Chemistry Communications 14 (2011) 916–919
919
[21] Crystal data for 1: C56H60N16Ni6O20, triclinc, space group P-1, a=11.062(2),
b=12.210(2), c=13.324(3)Å, α = 104.74(3), β = 102.29(3), γ = 108.71(3)o,
Z=1, ρcalcd =1.733 g cm-3, F(000)=836, R1 (wR2)=0.0667 (0.1716) (IN2σ(I)),
R1 (wR2)=0.0856 (0.1900) (all data), GOF=1.080.
[22] K.K. Nanda, K. Venkatsubramanian, D. Majundar, K. Nag, Synthesis of a novel
octaamino tetraphenol macrocyclic ligand and structure of a tetranuclear nickel
(II) complex, Inorg. Chem. 33 (1994) 1581–1582.
[23] E.C. Yang, W. Wernsdorfer, S. Hill, R.S. Edwards, M. Nakano, S. Maccagnano, L.N.
Zakharov, A.L. Rheingold, G. Christou, D.N. Hendrickson, Exchange bias in Ni4
single-molecule magnets, Polyhedron 22 (2003) 1727–1733.
[24] S. Mukherjee, T. Weyhermuller, E. Bothe, E. Wieghardt, P. Chaudhuri, Single-
Atom O-Bridged Urea in a Dinickel(II) Complex together with NiII4, CuII2 and CuII
4
Complexes of a Pentadentate Phenol-Containing Schiff Base with (O,N,O,N,O)-
Donor Atoms, Eur. J. Inorg. Chem. (2003) 863–875.