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Synthesis, structural characterization and magnetic properties of a novel metallacrown [Fe6(amshz)6(C3H7NO)6]·6CH3OH
Solid State Sciences 11 (2009) 2180–2183
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Solid State Sciences journal homepage: www.elsevier.com/locate/ssscie
Synthesis, structural characterization and magnetic properties of a novel metallacrown [Fe6(amshz)6(C3H7NO)6]$6CH3OH Tian-Pin Shu, Jun-Long Wen, Hai-Mei Feng, Ke-Wei Lei*, Hong-Ze Liang State Key Laboratory Base of Novel Functional Materials and Preparation Science, Institute of solid Materials Chemistry, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, PR China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 14 June 2009 Received in revised form 26 August 2009 Accepted 27 August 2009 Available online 2 September 2009
The novel 18-metallacrown-6 metallamacrocycle, with the formula of [Fe6(amshz)6(C3H7NO)6]$6CH3OH (1), has been synthesized by the self-assembly reaction of iron ions with N-substituted salicylhydrazide ligands. Six Fe(III) ions and six deprotonated N-acetyl-3-methylsalicylhydrazide (amshz3) ligands construct a planar 18-membered ring based on Fe–N–N–Fe linkage. Due to the coordination, the ligand enforces the stereochemistry of the Fe3þ ions as a propeller shape with alternating .DLDL. configurations. There exists a strong antiferromagnetic exchange interaction with meff ¼ 12.54 mB at 300 K between the Fe(III) spin 5/2 centers. Ó 2009 Elsevier Masson SAS. All rights reserved.
Keywords: Metallacrown Iron complexes Crystal structure Magnetic properties
1. Introduction There has been considerable interest in the rational design and construction of metallacrowns over the past decade, because of their potentially unique properties [1–7]. These metallacrowns exhibit selective recognition of cations and anions [1–3], can display intramolecular magnetic exchange interactions [1,5,6] and can be used as building blocks for two-dimensional or threedimensional network structures [8]. During the design of azametallacrowns, N-acyl-substituted salicylhydrazide ligands have often been used. These molecules can act as bifunctional ligands providing the nitrogen and oxygen donors to the metallacrown ring metals such as manganese [5,9–12], iron [5,13,14], cobalt [15], or gallium [14]. The ring size and nuclearity of azametallacrowns [16,17] can be controlled by the nature of the N-acyl substituent group. In recent years, there have been reports of metallacrowns of high nuclearity, but the ability to control their size, nuclearity, and physio-chemical properties are still a substantial challenge [18]. In the previous studies, we report a novel manganese(III) 18-metallacrown-6 compound, [Mn6(amshz)6(CH3OH)6]$6H2O [19] with the designed pentadentate ligand N-acetyl-3-methyl-salicylhydrazide (H3amshz). Herein, We designed a novel iron(III)
18-metallacrown-6 compound, [Fe6(amshz)6(C3H7NO)6]$6CH3OH (1) with the same ligand. 2. Experimental 2.1. Ligand synthesis The ligand N-acetyl-3-methyl-salicylhydrazide was synthesized by reacting acetic anhydride (2.0 g, 20.0 mmol) with 3methyl-salicyhyrazide (3.1 g, 18.0 mmol) in DMF (20 mL) at 0 C, then slowly warmed to room temperature and stirred for 2 h. After leaving overnight in a refrigerator, the resulting white precipitate was filtered and rinsed with chloroform and diethyl ether. Dried in vacuum. Yield: 93.9%. Melting point: 205–207. Anal. Cacl. for C10H12N2O3: C, 57.68; H, 5.81; N, 13.45%. Found: C, 57.46; H, 5.06; N, 13.23%. 1H NMR (400 MHz, DMSO-d6, 25 C), d ppm: 12.53 (1H, s, ArOH); 10.63(1H, s, ArCONH); 10.00 (1H, s, MeCONH); 7.73–7.71 (1H, d, o-ArH); 7.37–7.35 (1H, d, p-ArH); 6.84–6.80 (1H, t, m-Ar–H); 2.17 (3H, s, ArCH3); 1.94 (3H, s, COCH3). IR (cm1, KBr): v (O–H): 3450, v (N–H): 3230, v (C]O): 1665, v (C]N–N]C): 1633. 2.2. Complex synthesis
* Corresponding author. Tel./fax: þ8657487600874. E-mail address: [email protected] (Ke-Wei Lei). 1293-2558/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.solidstatesciences.2009.08.021
H3amshz (0.0208 g, 0.10 mmol) was dissolved in 5 mL DMF, FeCl3$3H2O (0.02701 g, 0.10 mmol) was dissolved in 10 mL methanol in another flask. The two solutions were mixed and stirred for
T.-P. Shu et al. / Solid State Sciences 11 (2009) 2180–2183
2.3. Crystallographic data collection and refinement of the structures
Table 1 The crystallographic date for complex 1. Empirical formula
2181
C78H96Fe6N18O24$6(CH3OH)
Fw (amu) 2197.08 T (K) 275(2) Crystal system, Space group Cubic, Pa-3 a (Å) 27.472(3) b (Å) 27.472(3) C (Å) 27.472(3) a ( ) 90.00 b( ) 90.00 g( ) 90.00 9899(2) V (Å3) 4, 1.474 Z, Dcalcd (g cm3) F (000) 4584 m (mm1) 0.942 Crystal size (mm3) 0.60 0.59 0.58 No. of date/restraints/parameters 74923/3778 /3201 3778 No. of reglections [I > 2s(I)] 2 1.094 Goodness-of-fit on F R1a ¼ 0.0398 Final R indices [I > 2s(I)] R indices (all date) wR2b ¼ 0.1186 P P a R1 ðFÞ ¼ jjF j jFc jj= jFo j. Po P b wR2 ðF2Þ ¼ ½ wðFo2 Fc2 Þ2 = wðFo2 Þ2 1=2 ; w ¼ 1/[s2(F2o)þ (0.1200P)2 þ 18.3337P], P ¼ (F2o þ 2F2c )/3.
The crystals of 1 were mounted in glass capillaries with the mother liquid to prevent the loss of the structural solvent molecules during X-ray diffraction data collection. Intensity data were collected at 275(2) K with graphite monochromatic MoKa radiation (l ¼ 0.71073 Å) on a Rigaku R-AXIS RAPID diffractometer. From a total of 74, 923 reflections corrected by SADABS [20] in the 3.00 q 27.42 range, 3778 were independent with Rint ¼ 0.0409, 210 parameters, of which 3201 observed reflections with I > 2s(I) were used in the structural analysis. The structure was solved by direct methods and all non-hydrogen atoms were refined with anisotropic thermal parameters. All hydrogen atoms were located in calculated positions or in the positions from difference Fourier map. The positions and anisotropy from differences of non-hydrogen atoms were refined on F2 by fullmatrix least-squares techniques with the SHELXTL program package [21,22]. The final refinement converged at R1 ¼ 0.0398, wR2 ¼ 0.1186. Details of the crystallographic data are given in Table 1.
3 min with the color of the mixture changing to dark brown, then filtered. Dark brown block crystals suitable for X-ray diffraction were obtained after 5 weeks. Yield: 60.3%. Anal. Cacl. for C78H96Fe6N18O24$6(CH3OH) : C, 45.88; H, 5.46; N, 11.47; Fe, 15.29%; Found: C, 45.47; H, 5.03; N, 11.26; Fe, 15.89%. IR (cm1, KBr): v (C]N–N]C): 1606, v (C]O): 1651, v (N–C]O): 1657, v (C–O)phenolic: 1232.
3.1. Infrared spectrum
3. Results and discussion
In the IR spectrum of the ligand, the bands at 3450 cm1 and 3230 cm1 are attributed to stretching vibration of v (O–H) phenolic and v (N–H) respectively. A strong band at 1665 cm1 and medium-strong band at 1633 cm1 are assigned to v (C]O) and v
Fig. 1. Molecular structure of compound 1 with atom labeling. All hydrogen atoms have been omitted for clarity.
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Table 2 Selected bond distances (Å) and angles ( ) of the title compound. Bond distance Fe(1)–O(1) Fe(1)–N(1) Fe(1)–O(2) N(1)–N(2)
2.0547(17) 2.0466(19) 2.0014(16) 1.414(3)
Fe(1)–O(3) Fe(1)–O(4) Fe(1)–N(2)
1.8934(17) 2.0741(18) 2.1093(19)
Bond angles O(1)–Fe(1)–N(1) O(1)–Fe(1)–O(3) N(1)–Fe(1)–O(3) O(1)–Fe(1)–O(2) N(1)–Fe(1)–O(2) O(3)–Fe(1)–O(2) O(1)–Fe(1)–N(2) N(1)–Fe(1)–N(2)
75.59(7) 162.31(7) 86.73(7) 96.80(7) 172.06(7) 100.86(7) 89.18(7) 105.57(7)
O(3)–Fe(1)–N(2) O(2)–Fe(1)–N(2) O(1)–Fe(1)–O(4) N(1)–Fe(1)–O(4) O(3)–Fe(1)–O(4) O(2)–Fe(1)–O(4) N(2)–Fe(1)–O(4)
95.95(7) 76.19(7) 84.98(7) 92.27(7) 95.61(8) 84.72(7) 159.23(7)
(C]N–N]C) vibrations of the salicylhydrazide ligand. In the title compound, the absence of the N–H and C]O stretching vibration bands is consistent with the deprotonation of the CONH groups and coordination to the Fe(III) ion. The disappearance of the band at 3450 cm1 and the appearance of the bands at 1352 and 1240 cm1 support the involvement of phenolic oxygen in coordination through deprotonation. The deprotonation and coordination are also confirmed by the band at 658 cm1, attributed to M–O linkages (phenolic and enolic oxygen), and the band at 549 cm1 assigned to M–N linkage [15,23]. 3.2. Structure The title compound 1 crystallizes in the cubic system and space group Pa-3. The molecular structure of compound 1 is shown in Fig. 1. Important bond distances and bond angles are presented in Table 2. The crystal structure of compound 1 (Fig. 1) is similar to that of the Mn(III) compound [19]. The structure exhibits a hexanuclear ring of iron atoms linked by six hydrazide N–N groups. The deprotonated ligand amshz3 acts as a trianionic pentadentate bridging ligand and coordinates to Fe(III) cations via three oxygen atoms and two hydrazine nitrogen atoms (Scheme 1). One phenolate oxygen atom, O3; one carbonyl oxygen atom, O2; and one hydrazide nitrogen, N1; of the ligand are bound to one Fe3þ cation, and the other carbonyl oxygen atom, O1; and the other hydrazide nitrogen atom, N2; in the same ligand are chelated to an adjacent Fe3þ cation and whole atoms in the ligand are almost in coplane. Therefore, the ligand allow for the propeller configuration all of Fe3þ cations into an alternating L and D stereochemistry. All iron atoms are in a distorted octahedral FeN2O4 environment. The average neighboring Fe–Fe interatomic distances is 4.909 Å. The average Fe–Fe–Fe inter-atomic angles is 115.96 . The interatomic distance of N1–N2 in the 18-membered core ring is 1.414(3) Å. The average Fe–N2 distance of 2.1093 Å is about 0.0627 Å longer than the average base Fe–N1 distance of 2.0466 Å. The approximate dimension of the oval-shaped cavity in the
Fig. 2. Plots of cmT (ueff), c1 m vs temperature (T) of complex 1 and cm vs temperature (T) from 2–300 K of compound 1.
molecule of the title compound is 6.732 Å in diameter at the entrance, about 9.665 Å at its largest diameter, and approximately 4.602 Å in depth. 3.3. Magnetic study The magnetic behavior of the title compound is shown in Fig. 2 in the temperature range of 2–300 K. The molar effective magnetic moment meff ¼ (8 cmT)1/2 of 1 decreased slightly with the temperature from 12.54 mB at 300 K to 8.78 mB at 58 K. Below 58 K, it rapidly decreased to 1.45 mB at 2 K. This is the characteristic of antiferromagnetic exchange coupling between the Fe(III) spin 5/2 centers, a feature common to most polynuclear iron complexes. It is further confirmed by a fitting to the Curie–Weiss expression c(T) ¼ C/[T þ Q] with a negative Weiss constant (Q ¼ 94.35 K) and C ¼ 26.21 cm3 K mol1 within T > 58 K. 4. Conclusions In summary, we designed an effective ligand H3amshz to prepare a metallamacrocyclic iron compound Fe6(amshz)6(C3H7NO)6]$6CH3OH. It crystallizes in the cubic system and space group Pa-3. All the metal atoms in the ring adopt a propeller configuration, and have alternating L and D configurations. The magnetic properties of the metallacrown molecules are characterized by the magnetic moments meff with 12.54 mB at 300 K between the Fe3þ ion spins with S ¼ 2.5 in the cyclic system. Supplementary material CCDC 733436 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via http:// www.ccdc.cam.ac.uk/date_request/cif. Acknowledgments
Scheme 1. Ligand H3amshz and basic biding sites in the title compound.
We gratefully acknowledge the Talent Fund of Ningbo Municipal Natural Science Foundation (No.2008A610051), the Scientific Research Fund of Ningbo University (No. XK0710020) and K.C.Wong Magna Fund in Ningbo University, for the financial support of the work.
T.-P. Shu et al. / Solid State Sciences 11 (2009) 2180–2183
References [1] V.L. Pecoraro, A.J. Stemmler, B.R. Gibney, J.J. Bodwin, H. Wang, J.W. Kampf, A. Barwinski, in: K.D. Karlin (Ed.), Progress in Inorganic Chemistry, 45, Wiley, New York, 1997, p. 83. [2] M.S. Lah, V.L. Pecoraro, J. Am. Chem. Soc. 111 (1989) 7258. [3] M.-L. Lehaire, R. Scopelliti, H. Piotrowski, K. Severin, Angew. Chem. Int. Ed. 41 (2002) 1419. [4] R.W. Saalfrank, I. Bernt, M.M. Chowdhry, F. Hampel, G.B.M. Vaughan, Chem. Eur. J. 7 (2001) 2765. [5] S.-X. Liu, S. Lin, B.-Z. Lin, C.-C. Lin, J.-Q. Huang, Angew. Chem. Int. Ed. 40 (2001) 1084. [6] D. Gaynor, Z.A. Starikova, S. Ostrovsky, W. Haase, K.B. Nolan, Chem. Commun. (2002) 506. [7] M. Alexiou, C. Dendrinou-Samara, C.P. Raptopoulou, A. Terzis, D.P. Kessissoglou, Inorg. Chem. 41 (2002) 4732. [8] M. Moon, I. Kim, M.S. Lah, Inorg. Chem. 39 (2000) 2710. [9] R.P. John, K.J. Lee, M.S. Lah, Chem. Commun. (2004) 2660.
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[10] R.P. John, K.J. Lee, B.J. Kim, B.J. Suh, H. Rhee, M.S. Lah, Inorg. Chem. 44 (2005) 7109. [11] B. Kwak, H. Rhee, S. Park, M.S. Lah, Inorg. Chem. 37 (1998) 3599. [12] B. Kwak, H. Rhee, S. Park, M.S. Lah, Polyhedron 19 (2000) 1985. [13] S. Lin, S.-X. Liu, Z. Chen, B.-Z. Lin, S. Gao, Inorg. Chem. 43 (2004) 2222. [14] I. Kim, B. Kwak, M.S. Lah, Inorg. Chim. Acta 317 (2001) 12. [15] S. Lin, S.-X. Liu, J.-Q. Huang, C.-C. Lin, J. Chem. Soc. Dalton Trans. (2002) 1595. [16] G. Mezei, P. Baran, R.G. Raptis, Angew. Chem. Int. Ed. 43 (2004) 574. [17] R.V. Slone, K.D. Benkstein, S. Be´langer, J.T. Hupp, I.A. Guzei, A.L. Rheingold, Coord. Chem. Rev. 171 (1998) 221. [18] W.L. Liu, K.J. Lee, Mira Park, R.P. John, M.S. Lah, Inorg. Chem. 47 (2008) 8807. [19] T.-P. Shu, Z.-J. Chen, H.-M. Feng, J.-L. Wen, K.-W. Lei, Inorg. Chem. Commun. 12 (2009) 672. [20] G.M. Sheldrick, SADABS. University of Gottingen, Germany, 1996. [21] Bruker AXS Inc, SMART APEX (Version5.628), SAINTþ (Version 6.45) and SHELXTL- NT (Version 6.12). Bruker AXS Inc., Madison, WI, USA, 2001. [22] G.M. Sheldrick, SHELXS97 and SHELXL97. University of Gottingen, Germany,1997. [23] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds, fourth ed. John Wiley & Sons, New York, 1986.
Contents lists available at ScienceDirect
Solid State Sciences journal homepage: www.elsevier.com/locate/ssscie
Synthesis, structural characterization and magnetic properties of a novel metallacrown [Fe6(amshz)6(C3H7NO)6]$6CH3OH Tian-Pin Shu, Jun-Long Wen, Hai-Mei Feng, Ke-Wei Lei*, Hong-Ze Liang State Key Laboratory Base of Novel Functional Materials and Preparation Science, Institute of solid Materials Chemistry, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, PR China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 14 June 2009 Received in revised form 26 August 2009 Accepted 27 August 2009 Available online 2 September 2009
The novel 18-metallacrown-6 metallamacrocycle, with the formula of [Fe6(amshz)6(C3H7NO)6]$6CH3OH (1), has been synthesized by the self-assembly reaction of iron ions with N-substituted salicylhydrazide ligands. Six Fe(III) ions and six deprotonated N-acetyl-3-methylsalicylhydrazide (amshz3) ligands construct a planar 18-membered ring based on Fe–N–N–Fe linkage. Due to the coordination, the ligand enforces the stereochemistry of the Fe3þ ions as a propeller shape with alternating .DLDL. configurations. There exists a strong antiferromagnetic exchange interaction with meff ¼ 12.54 mB at 300 K between the Fe(III) spin 5/2 centers. Ó 2009 Elsevier Masson SAS. All rights reserved.
Keywords: Metallacrown Iron complexes Crystal structure Magnetic properties
1. Introduction There has been considerable interest in the rational design and construction of metallacrowns over the past decade, because of their potentially unique properties [1–7]. These metallacrowns exhibit selective recognition of cations and anions [1–3], can display intramolecular magnetic exchange interactions [1,5,6] and can be used as building blocks for two-dimensional or threedimensional network structures [8]. During the design of azametallacrowns, N-acyl-substituted salicylhydrazide ligands have often been used. These molecules can act as bifunctional ligands providing the nitrogen and oxygen donors to the metallacrown ring metals such as manganese [5,9–12], iron [5,13,14], cobalt [15], or gallium [14]. The ring size and nuclearity of azametallacrowns [16,17] can be controlled by the nature of the N-acyl substituent group. In recent years, there have been reports of metallacrowns of high nuclearity, but the ability to control their size, nuclearity, and physio-chemical properties are still a substantial challenge [18]. In the previous studies, we report a novel manganese(III) 18-metallacrown-6 compound, [Mn6(amshz)6(CH3OH)6]$6H2O [19] with the designed pentadentate ligand N-acetyl-3-methyl-salicylhydrazide (H3amshz). Herein, We designed a novel iron(III)
18-metallacrown-6 compound, [Fe6(amshz)6(C3H7NO)6]$6CH3OH (1) with the same ligand. 2. Experimental 2.1. Ligand synthesis The ligand N-acetyl-3-methyl-salicylhydrazide was synthesized by reacting acetic anhydride (2.0 g, 20.0 mmol) with 3methyl-salicyhyrazide (3.1 g, 18.0 mmol) in DMF (20 mL) at 0 C, then slowly warmed to room temperature and stirred for 2 h. After leaving overnight in a refrigerator, the resulting white precipitate was filtered and rinsed with chloroform and diethyl ether. Dried in vacuum. Yield: 93.9%. Melting point: 205–207. Anal. Cacl. for C10H12N2O3: C, 57.68; H, 5.81; N, 13.45%. Found: C, 57.46; H, 5.06; N, 13.23%. 1H NMR (400 MHz, DMSO-d6, 25 C), d ppm: 12.53 (1H, s, ArOH); 10.63(1H, s, ArCONH); 10.00 (1H, s, MeCONH); 7.73–7.71 (1H, d, o-ArH); 7.37–7.35 (1H, d, p-ArH); 6.84–6.80 (1H, t, m-Ar–H); 2.17 (3H, s, ArCH3); 1.94 (3H, s, COCH3). IR (cm1, KBr): v (O–H): 3450, v (N–H): 3230, v (C]O): 1665, v (C]N–N]C): 1633. 2.2. Complex synthesis
* Corresponding author. Tel./fax: þ8657487600874. E-mail address: [email protected] (Ke-Wei Lei). 1293-2558/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.solidstatesciences.2009.08.021
H3amshz (0.0208 g, 0.10 mmol) was dissolved in 5 mL DMF, FeCl3$3H2O (0.02701 g, 0.10 mmol) was dissolved in 10 mL methanol in another flask. The two solutions were mixed and stirred for
T.-P. Shu et al. / Solid State Sciences 11 (2009) 2180–2183
2.3. Crystallographic data collection and refinement of the structures
Table 1 The crystallographic date for complex 1. Empirical formula
2181
C78H96Fe6N18O24$6(CH3OH)
Fw (amu) 2197.08 T (K) 275(2) Crystal system, Space group Cubic, Pa-3 a (Å) 27.472(3) b (Å) 27.472(3) C (Å) 27.472(3) a ( ) 90.00 b( ) 90.00 g( ) 90.00 9899(2) V (Å3) 4, 1.474 Z, Dcalcd (g cm3) F (000) 4584 m (mm1) 0.942 Crystal size (mm3) 0.60 0.59 0.58 No. of date/restraints/parameters 74923/3778 /3201 3778 No. of reglections [I > 2s(I)] 2 1.094 Goodness-of-fit on F R1a ¼ 0.0398 Final R indices [I > 2s(I)] R indices (all date) wR2b ¼ 0.1186 P P a R1 ðFÞ ¼ jjF j jFc jj= jFo j. Po P b wR2 ðF2Þ ¼ ½ wðFo2 Fc2 Þ2 = wðFo2 Þ2 1=2 ; w ¼ 1/[s2(F2o)þ (0.1200P)2 þ 18.3337P], P ¼ (F2o þ 2F2c )/3.
The crystals of 1 were mounted in glass capillaries with the mother liquid to prevent the loss of the structural solvent molecules during X-ray diffraction data collection. Intensity data were collected at 275(2) K with graphite monochromatic MoKa radiation (l ¼ 0.71073 Å) on a Rigaku R-AXIS RAPID diffractometer. From a total of 74, 923 reflections corrected by SADABS [20] in the 3.00 q 27.42 range, 3778 were independent with Rint ¼ 0.0409, 210 parameters, of which 3201 observed reflections with I > 2s(I) were used in the structural analysis. The structure was solved by direct methods and all non-hydrogen atoms were refined with anisotropic thermal parameters. All hydrogen atoms were located in calculated positions or in the positions from difference Fourier map. The positions and anisotropy from differences of non-hydrogen atoms were refined on F2 by fullmatrix least-squares techniques with the SHELXTL program package [21,22]. The final refinement converged at R1 ¼ 0.0398, wR2 ¼ 0.1186. Details of the crystallographic data are given in Table 1.
3 min with the color of the mixture changing to dark brown, then filtered. Dark brown block crystals suitable for X-ray diffraction were obtained after 5 weeks. Yield: 60.3%. Anal. Cacl. for C78H96Fe6N18O24$6(CH3OH) : C, 45.88; H, 5.46; N, 11.47; Fe, 15.29%; Found: C, 45.47; H, 5.03; N, 11.26; Fe, 15.89%. IR (cm1, KBr): v (C]N–N]C): 1606, v (C]O): 1651, v (N–C]O): 1657, v (C–O)phenolic: 1232.
3.1. Infrared spectrum
3. Results and discussion
In the IR spectrum of the ligand, the bands at 3450 cm1 and 3230 cm1 are attributed to stretching vibration of v (O–H) phenolic and v (N–H) respectively. A strong band at 1665 cm1 and medium-strong band at 1633 cm1 are assigned to v (C]O) and v
Fig. 1. Molecular structure of compound 1 with atom labeling. All hydrogen atoms have been omitted for clarity.
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T.-P. Shu et al. / Solid State Sciences 11 (2009) 2180–2183
Table 2 Selected bond distances (Å) and angles ( ) of the title compound. Bond distance Fe(1)–O(1) Fe(1)–N(1) Fe(1)–O(2) N(1)–N(2)
2.0547(17) 2.0466(19) 2.0014(16) 1.414(3)
Fe(1)–O(3) Fe(1)–O(4) Fe(1)–N(2)
1.8934(17) 2.0741(18) 2.1093(19)
Bond angles O(1)–Fe(1)–N(1) O(1)–Fe(1)–O(3) N(1)–Fe(1)–O(3) O(1)–Fe(1)–O(2) N(1)–Fe(1)–O(2) O(3)–Fe(1)–O(2) O(1)–Fe(1)–N(2) N(1)–Fe(1)–N(2)
75.59(7) 162.31(7) 86.73(7) 96.80(7) 172.06(7) 100.86(7) 89.18(7) 105.57(7)
O(3)–Fe(1)–N(2) O(2)–Fe(1)–N(2) O(1)–Fe(1)–O(4) N(1)–Fe(1)–O(4) O(3)–Fe(1)–O(4) O(2)–Fe(1)–O(4) N(2)–Fe(1)–O(4)
95.95(7) 76.19(7) 84.98(7) 92.27(7) 95.61(8) 84.72(7) 159.23(7)
(C]N–N]C) vibrations of the salicylhydrazide ligand. In the title compound, the absence of the N–H and C]O stretching vibration bands is consistent with the deprotonation of the CONH groups and coordination to the Fe(III) ion. The disappearance of the band at 3450 cm1 and the appearance of the bands at 1352 and 1240 cm1 support the involvement of phenolic oxygen in coordination through deprotonation. The deprotonation and coordination are also confirmed by the band at 658 cm1, attributed to M–O linkages (phenolic and enolic oxygen), and the band at 549 cm1 assigned to M–N linkage [15,23]. 3.2. Structure The title compound 1 crystallizes in the cubic system and space group Pa-3. The molecular structure of compound 1 is shown in Fig. 1. Important bond distances and bond angles are presented in Table 2. The crystal structure of compound 1 (Fig. 1) is similar to that of the Mn(III) compound [19]. The structure exhibits a hexanuclear ring of iron atoms linked by six hydrazide N–N groups. The deprotonated ligand amshz3 acts as a trianionic pentadentate bridging ligand and coordinates to Fe(III) cations via three oxygen atoms and two hydrazine nitrogen atoms (Scheme 1). One phenolate oxygen atom, O3; one carbonyl oxygen atom, O2; and one hydrazide nitrogen, N1; of the ligand are bound to one Fe3þ cation, and the other carbonyl oxygen atom, O1; and the other hydrazide nitrogen atom, N2; in the same ligand are chelated to an adjacent Fe3þ cation and whole atoms in the ligand are almost in coplane. Therefore, the ligand allow for the propeller configuration all of Fe3þ cations into an alternating L and D stereochemistry. All iron atoms are in a distorted octahedral FeN2O4 environment. The average neighboring Fe–Fe interatomic distances is 4.909 Å. The average Fe–Fe–Fe inter-atomic angles is 115.96 . The interatomic distance of N1–N2 in the 18-membered core ring is 1.414(3) Å. The average Fe–N2 distance of 2.1093 Å is about 0.0627 Å longer than the average base Fe–N1 distance of 2.0466 Å. The approximate dimension of the oval-shaped cavity in the
Fig. 2. Plots of cmT (ueff), c1 m vs temperature (T) of complex 1 and cm vs temperature (T) from 2–300 K of compound 1.
molecule of the title compound is 6.732 Å in diameter at the entrance, about 9.665 Å at its largest diameter, and approximately 4.602 Å in depth. 3.3. Magnetic study The magnetic behavior of the title compound is shown in Fig. 2 in the temperature range of 2–300 K. The molar effective magnetic moment meff ¼ (8 cmT)1/2 of 1 decreased slightly with the temperature from 12.54 mB at 300 K to 8.78 mB at 58 K. Below 58 K, it rapidly decreased to 1.45 mB at 2 K. This is the characteristic of antiferromagnetic exchange coupling between the Fe(III) spin 5/2 centers, a feature common to most polynuclear iron complexes. It is further confirmed by a fitting to the Curie–Weiss expression c(T) ¼ C/[T þ Q] with a negative Weiss constant (Q ¼ 94.35 K) and C ¼ 26.21 cm3 K mol1 within T > 58 K. 4. Conclusions In summary, we designed an effective ligand H3amshz to prepare a metallamacrocyclic iron compound Fe6(amshz)6(C3H7NO)6]$6CH3OH. It crystallizes in the cubic system and space group Pa-3. All the metal atoms in the ring adopt a propeller configuration, and have alternating L and D configurations. The magnetic properties of the metallacrown molecules are characterized by the magnetic moments meff with 12.54 mB at 300 K between the Fe3þ ion spins with S ¼ 2.5 in the cyclic system. Supplementary material CCDC 733436 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via http:// www.ccdc.cam.ac.uk/date_request/cif. Acknowledgments
Scheme 1. Ligand H3amshz and basic biding sites in the title compound.
We gratefully acknowledge the Talent Fund of Ningbo Municipal Natural Science Foundation (No.2008A610051), the Scientific Research Fund of Ningbo University (No. XK0710020) and K.C.Wong Magna Fund in Ningbo University, for the financial support of the work.
T.-P. Shu et al. / Solid State Sciences 11 (2009) 2180–2183
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