Design, synthesis, structure and magnetic behavior of a high spin binuclear Fe(III) complex of N-(1-ethanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl) amine

Article abstract of DOI:10.1016/j.inoche.2010.06.014

The Mannich reaction of 2-aminoethanol, 2-tert-butyl-4-methylphenol, and formaldehyde at the ratio sets of 1:2:2 provided a new ligand, N-(1-ethanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl)amine (H ₃L). In the presence of base, H₃

Full text of DOI:10.1016/j.inoche.2010.06.014

Inorganic Chemistry Communications 13 (2010) 1061–1063
Contents lists available at ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Design, synthesis, structure and magnetic behavior of a high spin binuclear Fe(III)
complex of N-(1-ethanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl) amine
a
b
a
a,
Xing-wu Tan , Bai-mu Wang , Ye Wang , Shu-zhong Zhan ⁎
a
College of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou, 510640, China
Office of Rongcheng Vocational College, Rongcheng Vocational College, Rong Cheng, 47660, China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
The Mannich reaction of 2-aminoethanol, 2-tert-butyl-4-methylphenol, and formaldehyde at the ratio sets of
Received 7 April 2010
Accepted 3 June 2010
Available online 10 June 2010
1
:2:2 provided a new ligand, N-(1-ethanol)-N,N-bis(3-tert-butyl-5-methyl-2-hydroxybenxyl)amine (H
In the presence of base, H L reacted with FeCl ·6H O to form a dinuclear Fe(III) complex [Fe ] 1. The value
of μeff at room temperature (5.95 μ ), is much less than the expected spin-only value (8.37 μ ) of two high
3
L).
3
3
2
2 2
L
B
B
3
+
1/2
3+
spin (hs) Fe (S=5/2) ions [μ=g[∑ZS(S+1)] ], indicating there were strong interactions between Fe
ions. The effective magnetic moment (μeff) decreased abruptly with cooling to a minimum value of 0.1 μ
K. It was worth noting that Fe3+ ions of 1 exhibited thermally induced quartet↔doublet spin transitions,
and these transitions were abrupt. The magnetic behaviors of 1 denoted the occurrence of intramolecular
Keywords:
B
at
High spin Fe(III) complex
Crystal structure
Magnetic properties
2
−
1
anti-ferromagnetic interactions. J (−13.58 cm ) agrees with the result from Gorun–Lippard equation, −J
−
1
(
cm )=Aexp(BP(Å)=12.9).
©
2010 Elsevier B.V. All rights reserved.
Dinuclear metal, (i.e., copper, iron) complexes of chelating
alkoxide and aryl-oxide ligands have attracted considerable interest
due to the structural elucidation of metalloenzymes and redox
catalysts, as well as the mechanistic understanding of spin-coupled
systems [1].
We apply the concept of ligand-controlled magnetic interaction to
design and synthesize new metal–organic magnetic molecules with
exchangeable ligands defining their magnetic properties. In this
paper, we report here the preparation, structure determination, and
magnetic properties of a high spin Fe(III) complex of the phenolate
Particular interest has been directed towards the exchange
phenomena in di- and polynuclear complexes, in which studies,
have led to essential insights into magnetostructural correlations [2].
It is well-known that in O-bridged systems the M–O–M angle plays a
vital role in determining the nature of magnetic exchange between
the metal ions [3,4].
The study of magnetic exchange mechanisms between metal
centers will be useful in finding suitable building blocks for the
assembly of new magnetic materials and in the development of new
redox catalysts. An approach toward this important goal is the design
and preparation of unique ligands that impart novel chemistry when
incorporated into the metal coordination sphere. The use of different
bridging ligands and well-designed polydentate ligands has afforded
an impressive array of nuclear coordination complexes with new
architectures. Among them, the chelating phenolate groups have
attracted our attention, as these compounds have remarkable
bridging ability to afford multinuclear complexes possessing poten-
tially useful for the development of new magnetic materials and
catalysts [5,6].
ligand, H
The Mannich reaction of 2-tert-butyl-4-methylphenol, 2-ami-
noethanol, and formaldehyde gave a new ligand H L. In the presence
of triethylamine, the reaction of H L and FeCl ·6H O provided a high
spin dinuclear Fe(III) complex 1 (Scheme 2) [7].
3
L (Scheme 1).
3
3
3
2
The molecular structure of 1 (Fig. 1) was built by two ligand (L3−)
molecules, two iron atoms, and one ethyl acetate molecule [8]. The
coordination environment around the iron atom was described as
distorted trigonal bipyramidal. The iron atom (Fe1) was bonded to two
phenolate oxygens (O(3), O(6)), two hydroxy oxygens (O(1), O(2)) and
one amine nitrogen (N(1)). The observed Fe–O bond distances fall in the
⁎
Corresponding author. Fax: +86 20 87112053.
E-mail address: shzhzhan@scut.edu.cn (S. Zhan).
Scheme 1. Structure of Ligand.
1387-7003/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2010.06.014

1062
X. Tan et al. / Inorganic Chemistry Communications 13 (2010) 1061–1063
Scheme 2. Schematic representation of the synthesis of 1.
range of 1.837(3) to 1.987(3) Å. The average Fe–N distance (2.178 Å)
was longer than the octahedral Fe–N distance of 2.15 Å [9]. Two iron
centers were separated by 3.142 Å, a value that was similar to those
found in other oxygen-bridged dinuclear iron compounds [10]. Fe–O–Fe
angles were 104.789(14) and 105.51(14)°, respectively. The bridging
pane containing Fe(1), O(6), Fe(2), O(3) was almost planar with the
torsion angle O(6)–Fe(1)–O(3)–Fe(2) of 1.78°.
The magnetic property of complex 1 was carried out in the range of
2–300 K, and was shown in Fig. 2 in the form of χ vs T. The value of
), was much less than the expected
M
μ
eff at room temperature (5.95 μ
B
3+
spin-only value (8.37 μ
B
) of two high spin (hs) Fe
(S=5/2) ions
1/2
[μ=g[∑ZS(S+1)] ], indicating there were strong interactions
between Fe3 ions. The effective magnetic moment (μeff) decreased
abruptly with cooling to a minimum value of 0.1 μB at 2 K. It is worth
+
Fig. 1. Molecular structure of 1. Selected bond distances (Å) and angles (°) are as follows: Fe(1)–O(2), 1.837(3); Fe(1)–O(1), 1.842(3); Fe(1)–O(3), 1.973(3); Fe(1)–O(6), 1.980(3);
Fe(1)–N(1), 2.192(4); Fe(2)–O(5), 1.854(3); Fe(2)–O(4), 1.856(3); Fe(2)–O(3), 1.975(3); Fe(2)–O(6), 1.987(3); Fe(2)–N(2), 2.164(4); O(2)–Fe(1)–O(1), 113.56(15); O(2)–Fe(1)–
O(3), 121.66(14); O(1)–Fe(1)–O(3), 124.02(14), O(2)–Fe(1)–O(6), 101.76(13); O(1)–Fe(1)–O(6), 103.18(13); O(3)–Fe(1)–O(6), 74.93(12); O(2)–Fe(1)–N(1), 91.97(13); O(1)–Fe
(1)–N(1), 90.96(13); O(3)–Fe(1)–N(1), 79.17(13); O(6)–Fe(1)–N(1), 154.10(13); O(5)–Fe(2)–O(4), 113.31(14); O(5)–Fe(2)–O(3), 101.73(13); O(4)–Fe(2)–O(3), 102.76(13); O
(5)–Fe(2)–O(6), 118.03(14); O(4)–Fe(2)–O(6), 128.03(13); O(3)–Fe(2)–O(6), 74.73(12); O(5)–Fe(2)–N(2), 93.67(13); O(4)–Fe(2)–N(2), 90.60(13); O(3)–Fe(2)–N(2), 153.40
(13); O(6)–Fe(2)–N(2), 78.91(13); Fe(1)–O(3)–Fe(2), 105.51(14).

X. Tan et al. / Inorganic Chemistry Communications 13 (2010) 1061–1063
1063
Appendix A. Supplementary Data
CCDC 772101 contains the supplementary crystallographic data of
. The data can be obtained free of charge from The Cambridge
1
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/
cif.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.inoche.2010.06.014.
References
[
1] (a) D.M. Kurtz, Chem. Rev. 90 (1990) 585–606;
(
(
b) B.J. Wallar, J.D. Lipscomb, Chem. Rev. 96 (1996) 2625–2658;
c) E.I. Solomon, T.C. Brunold, M.I. Davis, J.N. Kemsley, S.K. Lee, N. Lehnert, F.
Neese, A.J. Skulan, Y.-S. Yang, J. Zhou, Chem. Rev. 100 (2000) 235–350;
d) J. Du Bois, T.J. Mizoguchi, S. Lippard, Coord. Chem. Rev. 200–202 (2000)
(
4
43–485;
M
Fig. 2. Plot of the temperature dependence of the χ for 1.
(
(
e) E.Y. Tshuva, S. Lippard, J. Chem. Rev. 104 (2004) 987–1012;
f) G.J.P. Britovsek, V.C. Gibson, D.F. Wass, Angew. Chem. Int. Ed. 38 (1999)
428–447.
noting that FeIII ions of 1 exhibit thermally induced quartet↔doublet
spin transitions, and these transitions were abrupt.
Assuming isotropic exchange, the experimental magnetic data
was simulated for the dimeric Fe(III) system based on the spin
[
[
2] (a) S.M. Gorun, S.J. Lippard, Inorg. Chem. 30 (1991) 1625–1630;
(b) J. Jullien, G. Juhasz, P. Mialane, E. Dumas, C.R. Mayer, J. Marrot, E. Riviere, E.L.
Bominaar, E. Munck, F. Secheresse, Inorg. Chem. 45 (2006) 6922–6927.
3] L. Merz, W. Haase, J. Chem. Soc. Dalton Trans. (1980) 875–879;
(
c) E. Labisbal, L. Rodriguez, O. Souto, A. Sousa-Pedrares, J. Garcia-Vazquez, J.
Romero, A. Sousa, M. Yanez, F. Orallob, J. Real, Dalton Trans. (2009)
8644–8656.
1 2 1 2
Hamiltonian H=−2JS S with the following equation (S =S =5/2)
[11]:
[
4] L.K. Thompson, S.K. Mandal, S.S. Tandon, J.N. Bridson, M.K. Park, Inorg. Chem. 35
2
2
(1996) 3117–3125.
χM = ð2Nβ g = kTÞ½ð55 + 30 exp ð−10J = kTÞ + 14 expð−18J = kTÞ
[5]
(a) E.Y. Tshuva, M. Versano, I. Goldberg, M. Kol, H. Weitman, Z. Goldschmidt,
Inorg. Chem. Commun. 2 (1999) 371–373;
+
+
+
5 expð−24J = kTÞ + expð−28J = kTÞÞ= ð11 + 9 expð−10J = kTÞ
7 expð−18J = kTÞ + 5 expð−24J = kTÞ + 3 expð−28J = kTÞ
expð−30J = kTÞÞꢀ
(
(
b) L.P. Rothwell, Acc. Chem. Res. 21 (1988) 153–159;
c) S.W. Schweiger, D.L. Tillison, M.G. Thorn, P.E. Fanwick, I.P. Rothwell, J. Chem.
Soc. Dalton Trans. (2001) 2401–2408;
(
(
d) M.J. Caulfield, T. Russo, D.H. Solomon, Aust. J. Chem. 53 (2000) 545–549;
e) B. Castellano, E. Solari, C. Florian, N. Re, A. Chiesi-Villa, C. Rizzoli, Chem. Eur. J.
5
(1999) 722–737;
Very good agreement between the theoretical and experimental
data was obtained by using the following parameters: g=2.0, J=
(f) L. Michalczyk, S. De Gala, J.W. Bruno, Organometallics 20 (2001) 5547–5556;
(
g) K.D. Karlin, R.W. Cruse, Y. Gultneh, J.C. Hayes, J. Zubieta, J. Am. Chem. Soc. 106
1984) 3372–3374;
h) T.N. Sorrell, M.L. Garrity, Inorg. Chem. 30 (1991) 210–215.
(
−
1
−
13.58 cm . In accordance with Gorun and Lippard [2a], the
(
magnitude of anti-ferromagnetic coupling was determined by the
structural parameter P, which represents half of the shortest super-
exchange pathway between two iron atoms. The relation between the
[6] (a) H. Nie, S.M.J. Aubin, M.S. Mashuta, C.-H. Wu, J.F. Richardson, D.N.
Hendrickson, R.M. Buchanan, Inorg. Chem. 34 (1995) 2382–2388;
(
b) S. Uhlenbrock, B. Krebs, Angew. Chem. Int. Ed Engl. 31 (1992) 1647–1648.
7] Synthesis of complex [Fe ] 1: A solution of 2-tert-butyl-4-methylphenol (3.28 g,
0.020 mol), 2-aminoethanol (0.61 g, 0.010 mol), and 37% aqueous formaldehyde
1.80 ml, 0.020 mol) in ethanol (50 ml) was refluxed for 8 h, a yellow powder was
obtained. After adding triethylamine (3.10 g, 0.030 mol), and FeCl ·6H O (2.70 g,
.010 mol) to above yellow mixture, the color of the solution changed from
[
2 2
L
−
1
P parameter and J was given by −J (cm )=Aexp(BP(Å)), where
1
1
(
A=8.763×10 and B=−12.663. Applying the structural parameter
3
2
P of complex 1 to the Gorun–Lippard equation resulted in J=
0
−
1
−
12.9 cm , which agrees with the experimental data.
yellow to deep red. The solution was allowed to evaporate to give red crystals,
which were collected and dried in vacuo (1.26 g, 27%, based on 2-tert-butyl-4-
In summary, the present study shows that the title ligand can build
methylphenol). Calcd for C52
6.97; H, 7.74; N, 3.01.
[8] Crystal data for 1: C56H80Fe N O , M=1020.92, Orthorhombic, P2(1)2(1)2(1),
2 2 6
H72Fe N O : C, 66.89; H, 7.72; N, 3.00; Found: C,
a high spin dinuclear iron(III) complex in which the structure and
properties can be controlled by the design of bridged ligands.
Currently we are exploring this line, as well as the assembly for
other metals.
6
2
2 8
o
a=9.6330(13), b=16.890(2), c=33.104(5) Å, α=90.00, β=90.00, γ=90.00 ,
3
−3
V=5386.1(13) Å , Z=4, Dc=1.259 Mgm , R
9] R.E. Norman, R.C. Holz, S. Menage, L. Que Jr, J.H. Zhang, C.J. O'Connor, Inorg. Chem.
9 (1990) 4629–4631.
[10] (a) R. Werner, S. Ostrovsky, K. Griesar, W. Haase, Inorg. Chim. Acta 326 (2001)
8–88;
1
=0.0657, wR2=0.1390.
[
2
Acknowledgments
7
(
b) A. Horn Jr, I. Vencato, A.J. Bortoluzzi, R. Hörner, R.A. Nome Silva, B. Spoganicz,
V. Drago, H. Terenzi, M.C.B. de Oliveira, R. Werner, W. Haase, A. Neves, Inorg.
Chim. Acta 358 (2005) 339–351;
This work was supported by the Research Foundation for Returned
Chinese Scholars Overseas of the 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.
(c) S.M. Gorun, S.J. Lippard, Inorg. Chem. 30 (1991) 1625–1630.
[
11] J.T. Wrobleski, David B. Brown, Inorg. Chem. 17 (1978) 2959–2961.