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Syntheses, crystal structures and magnetic properties of two FeIII–MnIII complexes based on manganese(III)-porphyrin and tetracyanideferrite(III) building blocks
Inorganic Chemistry Communications 19 (2012) 66–69
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
Syntheses, crystal structures and magnetic properties of two Fe III–Mn III complexes based on manganese(III)-porphyrin and tetracyanideferrite(III) building blocks Guo-Ling Li, Jing Nie, Hui Chen, Zhong-Hai Ni ⁎, Yun Zhao, Li-Fang Zhang School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu Province, PR China
a r t i c l e
i n f o
Article history: Received 15 December 2011 Accepted 14 February 2012 Available online 21 February 2012 Keywords: Cyanide-bridged Manganese(III)-porphyrin Crystal structure Magnetic property
a b s t r a c t A new cyanide-bridged Fe IIIMnIII binuclear complex {[Fe(bpy)(CN)4][Mn(TPP)(CH3OH)]}·CH3OH (1) [bpy = 2,2′-bipyridine, TPP = tetraphenylporphyrin] and an ion-pair compound {[Fe(bpy)(CN)4] [Mn(TNPP)(CH3OH)2]}·2CH3CN (2) [TNPP = tetra(p-nitrophenyl)porphyrin] have been synthesized based on two manganese(III)-porphyrin precursors [Mn(L)(H2O)2]ClO4 (L = TPP and TNPP) and one cyanidecontaining building block K[Fe(bpy)(CN)4]. The crystal structures of the two complexes have been determined by X-ray single crystal diffraction. Magnetic study reveals that complex 1 exhibits weak antiferromagnetic coupling between low-spin Fe(III) and high-spin Mn(III) through the cyanide bridge. © 2012 Elsevier B.V. All rights reserved.
In the field of molecular magnetochemistry, the selection of magnetic spin carrier, the design of organic coordination ligand and the arrangement of the bridging group are the important research focuses [1,2]. Among the numerous bridging group systems, cyanide group has attracted durative much attention because cyanide group can effectively transmit magnetic coupling and cyanide-bridged complexes can manifest some interestingly magnetic properties [3–15]. In the past decade, our group and several other groups have paid much attention on the design and synthesis of cyanide-bridged lowdimensional magnetic complexes based on manganese(III)-Schiff base building blocks because it is well known that Mn(III) ions can usually exhibits some excellent natures for the preparation of interesting magnetic materials [6,16–23]. Very recently, we focus our interest on the exploitation of manganese(III)-porphyrin precursors because not only they contain Mn(III) spin carrier, but also they comprise interesting porphyrin ligands [9,24]. Herein, we report the syntheses, crystal structures and magnetic properties of two new Fe III– Mn III complexes prepared by the reaction of K[Fe(bpy)(CN)4] with [Mn(TPP)(H2O)2]ClO4 and [Mn(TNPP)(H2O)2]ClO4, respectively. Deep brown block single crystals of 1 and 2 were obtained at room temperature by slow evaporation of a solution prepared by carefully mixing a acetonitrile/methanol solution (10 mL) of [Mn(L)(H2O)2] ClO4 [L = TPP (1), TNPP (2)] (0.1 mmol) and a methanol/water solution (10 mL) of K[Fe(bpy)(CN)4] (0.1 mmol). Yield: 57.2 mg (54.6%) for 1, and 61.0 mg (46.6%) for 2. Anal Calc. for C60H44FeMnN10O2 (1): C, 68.77; H, 4.24; N, 13.37%. Found: C, 68.59; H, 4.13; N, 13.26%. Main IR frequencies (KBr disk, cm − 1): 2158(vCN), 2116(vCN). Anal
⁎ Corresponding author. Tel.: + 86 0516 83883927. E-mail address: [email protected] (Z.-H. Ni). 1387-7003/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2012.02.012
Calc. for C64H46FeMnN16O10(2): C, 58.69; H, 3.54; N, 17.11%. Found: C, 58.54; H, 3.44; N, 16.99%. Main IR frequencies (KBr disk, cm − 1): 2119(vCN). The IR spectra in the range 2110–2160 cm − 1 exhibit two cyanide stretching absorption peaks for compound 1, indicating the presence of bridging and nonbridging cyanide ligands in [Fe(bpy)(CN)4] −. Moreover, the corresponding bridging CN group usually absorbs at a higher frequency than the terminal group. However, for complex 2, there is only one IR relative broad peak at 2119 cm − 1, corresponding to nonbridging cyanide groups. X-ray crystallography analysis [25] indicates that the crystal structure of 1 is a binuclear compound containing a [Mn(TPP)(H2O)2] − and a [Fe(bpy)(CN)4] − unit, in which two different metal centers are linked by a cyanide group from the [Fe(bpy)(CN)4] − building block, and the molecular structure of complex 1 is shown in Fig. 1. As for ion-pair complex 2, the crystal structure is described in Fig. 2. For complex 1, the iron(III) ion is coordinated by two nitrogen atoms from the bpy ligand and four carbon atoms from four cyanide groups, forming a slightly distorted octahedral geometry. The Fe–N bond distances are 1.986(3) Å for Fe–N(1) and 1.998(3) Å for Fe– N(2), respectively. The four Fe–C bond distances are similar, ranging from 1.898(3) Å to 1.942(3) Å. The Fe–C ≡ N linkages are almost collinear with angles ranging from 174.5(3)° to 177.9(3)°. The manganese(III) ion in complex 1 is six-coordinated with one nitrogen atom from the bridging cyanide group and an oxygen atom from the coordinated methanol molecule and four nitrogen atoms from the equatorial porphyrin ring. The Mn–Ncyanide and Mn–O bond lengths are 2.266(3) Å and 2.258(2) Å, respectively, showing the Jahn–Teller effect of the central Mn(III) ion. The averaged Mn–Nporphyrin bond distance is 1.997(3) Å. The Mn–C≡N angle is 152.8(2)°, which deviates largely from linearity. The Fe–-Mn distance through the bridging
G.-L. Li et al. / Inorganic Chemistry Communications 19 (2012) 66–69
67
3.5
Complex 1
3.3
5 S = 1/2 + 2
4
3.2
M/Nβ
χmT/emu K mol-1
3.4
3 2
S = 1.5 T = 2.0 K
1
3.1
0 0
1
2 3 H/10 kOe
4
5
3.0 0
50
100
150
200
250
300
T/K 4.0
Complex 2
Fig. 2. The crystal structure of complex 2 (All the H atoms and the solvent molecule are omitted for clarity), selected bond lengths (Å): Fe1–C1 1.961(4), Fe1–C2 1.913(4), Fe1– N3 1.981(3), Mn1–O1 2.262(2), Mn1–N4 2.019(2), Mn1–N5 2.008(2). Symmetry codes: i −x, y, −z + 1/2; ii −x + 1/2, −y + 3/2, −z.
5
3.0
S = 1/2 + 2
4 M/N β
cyanide group is 5.203(3) Å, and the shortest intermolecular metal– metal separation is 9.311(2) Å. The magnetic susceptibilities for complex 1 have been measured in the temperature range of 2–300 K under an applied field of 2000 Oe. A pot of χmT vs. T is shown in Fig. 3. The room temperature χmT values of complex 1 is 3.35 emu K mol − 1, which is close to the spin-only value 3.375 emu K mol − 1 anticipated for the isolated binuclear systems of high-spin Mn(III) (S = 2) and low-spin Fe(III) (S = 1/2) with g = 2.00. The χmT value keeps almost constant while the temperature decreasing until about 75 K, and then smoothly decreases to 3.13 emu K mol − 1 at 25 K. After that, the χmT value gradually increases to about 3.45 emu K mol − 1 at 5 K. Although the changing range of χmT value is relatively narrow, the variation tendency of the χmT curve clearly reveals that the magnetic interaction between the low-spin Fe(III) and high-spin Mn(III) through cyanide
3.5
χmT/emu K mol-1
Fig. 1. The crystal structure of complex 1 (The H atoms on the C atoms and the solvent molecule are omitted for clarity), selected bond lengths (Å) and angles (°): Fe1–C1 1.926(3), Mn1–N1 2.266(3), Fe1–-Mn1 5.203(3), Fe1–C1-N1 174.5(3), Mn1–C1–N1 152.8(2).
2.5
3 2
S = 1.5 T = 2.0 K
1
2.0 0
0
1
2
3 H/10 kOe
4
5
1.5 0
50
100
150
200
250
300
T/K Fig. 3. Temperature dependence of χmT for complexes 1 and 2, the blue lines represent the best fit (Inset: Field dependences of magnetization, the line and the broken line represent the Brillouin function that correspond to S = 3/2 and S = 2 + 1/2, respectively, based on g = 2.0).
bridge is weak antiferromagnetic. The magnetic susceptibilities in the whole temperature range obey Curie-Weiss law with small negative Weiss constant θ = −1.43 K and Curie constant C = 3.36 emu K mol − 1, indicating the occurrence of overall weak antiferromagnetic interactions in complex 1. The field dependence of magnetization of 1 measured in the field rang of 0–50 Oe at 2 K (Inset in Fig. 3) is nearly close to the Brillouin function curve based on the S = 3/2 spin state with g = 2.00, and is obviously lower than the data of the Brillouin curve based on S = 2 + 1/2 spin state assuming g = 2.00. This feature further indicates that the existence of overall antiferromagnetic coupling between the Fe(III) and Mn(III) ions. The magnetic property for 1 is different from those of cyanide-bridged FeIIIMnIIIFeIII trinuclar and FeIIIMnIII binuclear complexes based on a series of manganese(III)-porphyrins and cyanide-containing [Fe(L)(CN)2]− or [Fe(CN)6]3 − building blocks [24,26]. The magnetic properties of complex 2 are shown in Fig. 3. At room temperature, the χmT value is 3.57 emu K mol − 1. With decreasing the temperature, the χmT value keep nearly constant until about 20.0 K, then decreases quickly to 2.23 emu K mol − 1 at 2 K due to the intermolecular antiferromagnetic interaction and the zero-field splitting effect of magnetic anisotropic Mn(III) ion. The magnetic susceptibilities of complex 2 in the whole temperature range obeys
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G.-L. Li et al. / Inorganic Chemistry Communications 19 (2012) 66–69
Curie–Weiss law with small negative Weiss constant θ = – 0.71 K and Curie constant C = 3.58 emu K mol − 1. The difference for the magnetic susceptibilities of complexes 1 and 2 is due to there is antiferromagnetic coupling between Mn(III) and Fe(III) through cyanide bridge in complex 1. In order to evaluate the strength of intra-/inter-dimer magnetic coupling (J/zJ′) and zfs parameter (D) of Mn(III), the best fit for the ^ ¼ −2J S^Fe ⋅S^Mn þ experimental magnetic data above 25 K based on H ^ DMn S^2z − SMn ðS3Mn þ1Þ þ gbHS−zJ’ S^Tz S^Tz [22] (the fitting equation see Supporting Information), giving the fitting parameters J = –2.52(1) cm − 1, g = 1.99(1), DMn = 1.52(3) cm − 1, zJ’ = –0.14(3) cm − 1, and R = Σ[(χmT)obsd. − (χmT)calcd.] 2/Σ[(χmT) 2obsd.] = 5.22 × 10 − 5. It should be mentioned it is difficult to determine the sign of DMn based on the powder magnetic susceptibility data. The calculated DMn value (1.52 cm − 1) is normal for high-spin tetragonally elongated octahedral Mn(III) [22]. In addition, DMn and zJ′ are often correlated, and they should be treated with care. Complex 2 is a good model for the magnetic properties of Mn(III) compounds. The can be considered as isolated Mn(III) and Fe(III) ions, if the zero-field splitting (zfs) of the Mn(III) ion is considered. The best fit to the magnetic data in the whole temperature range using the expressions (see Supporting Information) on basis of 2 2 χ ionpair ¼ χ Mn þ χ Fe ¼ χ zfs þ χ Fe ¼ ð2χ ⊥ þ χ ∥ Þ=3 þ Ng3kTβ SFe ðSFe þ 1Þ gives the parameters g = 2.03(1), |DMn| = 3.5(2) cm − 1, zJ’ = −0.16(2) cm − 1 and R = 4.28 × 10 − 6. The results are similar to those of complex [Co(bpmb)(CN)2]6[Mn(5-Brsalpn)]6·12H2O [23]. In summary, two Fe III–Mn III complexes have been obtained based on manganese(III)-porphyrin and tetracyanideferrite(III) building blocks. Complex 1 shows cyanide-bridged Fe III–Mn III binuclear molecular structure, whereas complex 2 is an ion-pair compound. Magnetic investigation reveals the occurrence of overall weak antifferomagnetic coupling in the cyanide-bridged binuclear complex. This work further illustrates that manganese(III)-porphyrin and it's derivatives can be employed to assemble molecular magnetic complex and the molecular structures of them can be tuned by the peripheral substituted groups attached to the porphyrin precursor.
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Acknowledgements
[17]
This work was supported by the Nation Natural Science Foundation of China (No. 21176246), the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Fundamental Research Funds for the Central Universities (China University of Mining and Technology).
[18]
Appendix A. Supplementary material The supramolecular structures of compounds 1 and 2, and the magnetic properties of complex 2 can be found in Supporting Information file. Crystallographic data for the structure of complex 1 and 2 in this paper have been deposited at the Cambridge Crystallographic Data Center (CCDC 855982 for 1 and 855983 for 2). This information can be obtained free of charge at www.ccdc.cam.ac.uk/conts/ retrieving.html or from the Cambridge Crystallographic Data Centre (CCDC), 12 Union Road, Cambridge CB2 1EZ, United Kingdom; Fax: +44(0)1223-336033; e-mail: [email protected]. Supplementary data to this article can be found online at doi:10.1016/j.inoche. 2012.02.012. References [1] (a) R. Lescouëzec, M.L. Toma, J. Vaissermann, M. Verdaguer, F.S. Delgado, C. RuizPérez, F. Lloret, M. Julve, Design of single chain magnets through cyanidebearing six-coordinate complexes, Coord. Chem. Rev. 249 (2005) 2691–2729;
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Sato, Photoinduced metal-to-metal charge transfer toward single-chain magnet, J. Am. Chem. Soc. 132 (2010) 8250–8251. W. Li, S.-Z. Zhan, J.-G. Wang, W.-Y. Yan, Y.-F. Deng, The isolation and properties of an unexpected cyano-bridged complex [(H2O)CoII(dppm)2(μ-CN)CoIICl3]·C2H5OH, Inorg. Chem. Commun. 11 (2008) 681–683. D.-F. Li, R. Clérac, O. Roubeau, E. Harté, C. Mathonière, R.L. Bris, S.M. Holmes, Magnetic and optical bistability driven by thermally and photoinduced intramolecular electron transfer in a molecular cobalt–iron Prussian blue analogue, J. Am. Chem. Soc. 130 (2008) 252–258. M.G. Hilfiger, M.-M. Chen, T.V. Brinzari, T.M. Nocera, M. Shatruk, D.T. Petasis, J.L. Musfeldt, C. Achim, K.R. Dunbar, An unprecedented charge transfer induced spin transition in an Fe–Os cluster, Angew. Chem. Int. Ed. 49 (2010) 1410–1413. S.M. Neville, G.J. Halder, K.W. Chapman, M.B. Duriska, B. Moubaraki, K.S. Murray, C.J. Kepert, Guest tunable structure and spin crossover properties in a nanoporous coordination framework material, J. Am. Chem. Soc. 131 (2009) 12106–12108. R. Boča, I. Šalitroš, J. Kožíšek, J. Linares, J. Monco, F. Renz, Spin crossover in a heptanuclear mixed-valence iron complex, Dalton Trans. (2010) 2198–2200. K.S. Pedersen, M. Schau-Magnussen, J. Bendix, H. Weihe, A.V. Palii, S.I. Klokishner, S. Ostrovsky, O.S. Reu, H. Mutka, P.L.W. Tregenna-Piggott, Enhancing the blocking temperature in single-molecule magnets by incorporating 3d–5d exchange interactions, Chem. Eur. J. 16 (2010) 13458–13464. H. Miyasaka, H. Takahashi, T. Madanbashi, K. Sugiura, R. Clerac, H. Nojir, Cyanobridged MnIII3MIII (MIII= Fe, Cr) complexes: synthesis, structure, and magnetic properties, Inorg. Chem. 44 (2005) 5969–5971. H.-Y. Kwak, D.-W. Ryu, J.-W. Lee, J.-H. Yoon, H.-C. Kim, E.-K. Koh, J. Krinsky, C.-S. Hong, Cyanide-bridged Fe(III)−Mn(III) bimetallic systems assembled from the fac-Fe tricyanide and Mn schiff bases: structures, magnetic properties, and density functional theory calculations, Inorg. Chem. 49 (2010) 4632–4642. H.J. Choi, J.J. Sokol, J.R. Long, Raising the spin-reversal barrier in cyano-bridged single-molecule magnets: linear MnIII2MIII(CN)6 (M = Cr, Fe) species incorporating [(5-Brsalen)Mn]+ units, Inorg. Chem. 43 (2004) 1606–1608. H.-Z. Kou, Z.-H. Ni, C.-M. Liu, D.-Q. Zhang, A.-L. Cui, Cyanide-bridged 1D Mn(III)– Fe(III) bimetallic complexes: synthesis, crystal structure and magnetic properties, New J. Chem. 33 (2009) 2296–2299. Z.-H. Ni, L.-F. Zhang, V. Tangoulis, W. Wernsdorfer, A.-L. Cui, Os. Sato, H.-Z. Kou, Substituent effect on formation of heterometallic molecular wheels: synthesis, crystal structure, and magnetic properties, Inorg. Chem. 46 (2007) 6029–6037. Z.-H. Ni, J. Tao, W. Wernsdorfer, A.-L. Cui, H.-Z. Kou, Supramolecular metallomacrocycles based on trans-dicyanoferrite(III) building blocks: synthesis, crystal structure and magnetic properties, Dalton Trans. (2009) 2788–2794. Z.-H. Ni, L.-F. Zhang, A.-L. Cui, H.-Z. Kou, Synthesis, crystal structures and magnetic properties of cyanide-bridged macrocyclic complexes, Sci. China Ser. B–Chem. 52 (2009) 1444–1450. D.-P. Zhang, H.-L. Wang, L.-J. Tian, H.-Z. Kou, J.-Z. Jiang, Z.-H. Ni, Synthesis, crystal structures, and magnetic properties of cyanide-bridged Fe(III)–Mn(III) complexes based on manganese(III)-porphyrin and pyridinecarboxamide dicyanideiron(III) building blocks, Cryst. Growth Des. 9 (2009) 3989–3996. Crystal data for 1: C60H44FeMnN10O2, Mw = 1047.84, T = 123 K, triclinic, space group P1, a = 9.3108(19), b = 11.883(2), c = 12.098(2) Å, V = 1254.2(4) Å3, Z = 1, ρcalcd = 1.387 g cm− 3, μ = 0.597 mm− 1, λ(Mo Kα) = 0.71073 Å, F(000) = 541, 17258 measured reflections, 8773 unique reflections, 7850 observed reflections (I > 2σ(I)). R1 = 0.0384, wR2 = 0.0756(all data), GOF = 0.970 based on 366 parameters, largest difference peak and hole: 0.469/0.276 e Å− 3. Crystal date for 2: C64H46FeMnN16O10, Mw = 1309.96, T = 123 K, Monoclinic, space group C2/c, a = 15.261(3), b = 15.392(3), c = 25.217(5) Å, V = 5879(2) Å3, Z = 4, ρcalcd = 1.480 g cm− 3, μ = 0.538 mm− 1, λ(Mo Kα) = 0.71073 Å, F(000) =
G.-L. Li et al. / Inorganic Chemistry Communications 19 (2012) 66–69 2692, 18684 measured reflections, 5069 unique reflections, 3906 observed reflections (I > 2σ(I)). R1 = 0.0657, wR2 = 0.1547(all data), GOF = 0.987 based on 366 parameters, largest difference peak and hole: 0.942/− 0.521 e Å− 3. The structures of the two complexes were solved by the direct method and refined by full matrix least-squares on F2. Anisotropic thermal parameters were used
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for the non-hydrogen atoms. The hydrogen atoms attached to C and N atoms were added geometrically and refined using a riding model. [26] S. Huh, K.-T. Youm, Y.J. Park, A.J. Lough, M. Ohba, M.-J. Jun, Trinuclear MnIII–NC– FeIII–CN–MnIII ferromagnetic system, Bull. Korean Chem. Soc. 26 (2006) 1031–1302.
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
Syntheses, crystal structures and magnetic properties of two Fe III–Mn III complexes based on manganese(III)-porphyrin and tetracyanideferrite(III) building blocks Guo-Ling Li, Jing Nie, Hui Chen, Zhong-Hai Ni ⁎, Yun Zhao, Li-Fang Zhang School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu Province, PR China
a r t i c l e
i n f o
Article history: Received 15 December 2011 Accepted 14 February 2012 Available online 21 February 2012 Keywords: Cyanide-bridged Manganese(III)-porphyrin Crystal structure Magnetic property
a b s t r a c t A new cyanide-bridged Fe IIIMnIII binuclear complex {[Fe(bpy)(CN)4][Mn(TPP)(CH3OH)]}·CH3OH (1) [bpy = 2,2′-bipyridine, TPP = tetraphenylporphyrin] and an ion-pair compound {[Fe(bpy)(CN)4] [Mn(TNPP)(CH3OH)2]}·2CH3CN (2) [TNPP = tetra(p-nitrophenyl)porphyrin] have been synthesized based on two manganese(III)-porphyrin precursors [Mn(L)(H2O)2]ClO4 (L = TPP and TNPP) and one cyanidecontaining building block K[Fe(bpy)(CN)4]. The crystal structures of the two complexes have been determined by X-ray single crystal diffraction. Magnetic study reveals that complex 1 exhibits weak antiferromagnetic coupling between low-spin Fe(III) and high-spin Mn(III) through the cyanide bridge. © 2012 Elsevier B.V. All rights reserved.
In the field of molecular magnetochemistry, the selection of magnetic spin carrier, the design of organic coordination ligand and the arrangement of the bridging group are the important research focuses [1,2]. Among the numerous bridging group systems, cyanide group has attracted durative much attention because cyanide group can effectively transmit magnetic coupling and cyanide-bridged complexes can manifest some interestingly magnetic properties [3–15]. In the past decade, our group and several other groups have paid much attention on the design and synthesis of cyanide-bridged lowdimensional magnetic complexes based on manganese(III)-Schiff base building blocks because it is well known that Mn(III) ions can usually exhibits some excellent natures for the preparation of interesting magnetic materials [6,16–23]. Very recently, we focus our interest on the exploitation of manganese(III)-porphyrin precursors because not only they contain Mn(III) spin carrier, but also they comprise interesting porphyrin ligands [9,24]. Herein, we report the syntheses, crystal structures and magnetic properties of two new Fe III– Mn III complexes prepared by the reaction of K[Fe(bpy)(CN)4] with [Mn(TPP)(H2O)2]ClO4 and [Mn(TNPP)(H2O)2]ClO4, respectively. Deep brown block single crystals of 1 and 2 were obtained at room temperature by slow evaporation of a solution prepared by carefully mixing a acetonitrile/methanol solution (10 mL) of [Mn(L)(H2O)2] ClO4 [L = TPP (1), TNPP (2)] (0.1 mmol) and a methanol/water solution (10 mL) of K[Fe(bpy)(CN)4] (0.1 mmol). Yield: 57.2 mg (54.6%) for 1, and 61.0 mg (46.6%) for 2. Anal Calc. for C60H44FeMnN10O2 (1): C, 68.77; H, 4.24; N, 13.37%. Found: C, 68.59; H, 4.13; N, 13.26%. Main IR frequencies (KBr disk, cm − 1): 2158(vCN), 2116(vCN). Anal
⁎ Corresponding author. Tel.: + 86 0516 83883927. E-mail address: [email protected] (Z.-H. Ni). 1387-7003/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2012.02.012
Calc. for C64H46FeMnN16O10(2): C, 58.69; H, 3.54; N, 17.11%. Found: C, 58.54; H, 3.44; N, 16.99%. Main IR frequencies (KBr disk, cm − 1): 2119(vCN). The IR spectra in the range 2110–2160 cm − 1 exhibit two cyanide stretching absorption peaks for compound 1, indicating the presence of bridging and nonbridging cyanide ligands in [Fe(bpy)(CN)4] −. Moreover, the corresponding bridging CN group usually absorbs at a higher frequency than the terminal group. However, for complex 2, there is only one IR relative broad peak at 2119 cm − 1, corresponding to nonbridging cyanide groups. X-ray crystallography analysis [25] indicates that the crystal structure of 1 is a binuclear compound containing a [Mn(TPP)(H2O)2] − and a [Fe(bpy)(CN)4] − unit, in which two different metal centers are linked by a cyanide group from the [Fe(bpy)(CN)4] − building block, and the molecular structure of complex 1 is shown in Fig. 1. As for ion-pair complex 2, the crystal structure is described in Fig. 2. For complex 1, the iron(III) ion is coordinated by two nitrogen atoms from the bpy ligand and four carbon atoms from four cyanide groups, forming a slightly distorted octahedral geometry. The Fe–N bond distances are 1.986(3) Å for Fe–N(1) and 1.998(3) Å for Fe– N(2), respectively. The four Fe–C bond distances are similar, ranging from 1.898(3) Å to 1.942(3) Å. The Fe–C ≡ N linkages are almost collinear with angles ranging from 174.5(3)° to 177.9(3)°. The manganese(III) ion in complex 1 is six-coordinated with one nitrogen atom from the bridging cyanide group and an oxygen atom from the coordinated methanol molecule and four nitrogen atoms from the equatorial porphyrin ring. The Mn–Ncyanide and Mn–O bond lengths are 2.266(3) Å and 2.258(2) Å, respectively, showing the Jahn–Teller effect of the central Mn(III) ion. The averaged Mn–Nporphyrin bond distance is 1.997(3) Å. The Mn–C≡N angle is 152.8(2)°, which deviates largely from linearity. The Fe–-Mn distance through the bridging
G.-L. Li et al. / Inorganic Chemistry Communications 19 (2012) 66–69
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3.5
Complex 1
3.3
5 S = 1/2 + 2
4
3.2
M/Nβ
χmT/emu K mol-1
3.4
3 2
S = 1.5 T = 2.0 K
1
3.1
0 0
1
2 3 H/10 kOe
4
5
3.0 0
50
100
150
200
250
300
T/K 4.0
Complex 2
Fig. 2. The crystal structure of complex 2 (All the H atoms and the solvent molecule are omitted for clarity), selected bond lengths (Å): Fe1–C1 1.961(4), Fe1–C2 1.913(4), Fe1– N3 1.981(3), Mn1–O1 2.262(2), Mn1–N4 2.019(2), Mn1–N5 2.008(2). Symmetry codes: i −x, y, −z + 1/2; ii −x + 1/2, −y + 3/2, −z.
5
3.0
S = 1/2 + 2
4 M/N β
cyanide group is 5.203(3) Å, and the shortest intermolecular metal– metal separation is 9.311(2) Å. The magnetic susceptibilities for complex 1 have been measured in the temperature range of 2–300 K under an applied field of 2000 Oe. A pot of χmT vs. T is shown in Fig. 3. The room temperature χmT values of complex 1 is 3.35 emu K mol − 1, which is close to the spin-only value 3.375 emu K mol − 1 anticipated for the isolated binuclear systems of high-spin Mn(III) (S = 2) and low-spin Fe(III) (S = 1/2) with g = 2.00. The χmT value keeps almost constant while the temperature decreasing until about 75 K, and then smoothly decreases to 3.13 emu K mol − 1 at 25 K. After that, the χmT value gradually increases to about 3.45 emu K mol − 1 at 5 K. Although the changing range of χmT value is relatively narrow, the variation tendency of the χmT curve clearly reveals that the magnetic interaction between the low-spin Fe(III) and high-spin Mn(III) through cyanide
3.5
χmT/emu K mol-1
Fig. 1. The crystal structure of complex 1 (The H atoms on the C atoms and the solvent molecule are omitted for clarity), selected bond lengths (Å) and angles (°): Fe1–C1 1.926(3), Mn1–N1 2.266(3), Fe1–-Mn1 5.203(3), Fe1–C1-N1 174.5(3), Mn1–C1–N1 152.8(2).
2.5
3 2
S = 1.5 T = 2.0 K
1
2.0 0
0
1
2
3 H/10 kOe
4
5
1.5 0
50
100
150
200
250
300
T/K Fig. 3. Temperature dependence of χmT for complexes 1 and 2, the blue lines represent the best fit (Inset: Field dependences of magnetization, the line and the broken line represent the Brillouin function that correspond to S = 3/2 and S = 2 + 1/2, respectively, based on g = 2.0).
bridge is weak antiferromagnetic. The magnetic susceptibilities in the whole temperature range obey Curie-Weiss law with small negative Weiss constant θ = −1.43 K and Curie constant C = 3.36 emu K mol − 1, indicating the occurrence of overall weak antiferromagnetic interactions in complex 1. The field dependence of magnetization of 1 measured in the field rang of 0–50 Oe at 2 K (Inset in Fig. 3) is nearly close to the Brillouin function curve based on the S = 3/2 spin state with g = 2.00, and is obviously lower than the data of the Brillouin curve based on S = 2 + 1/2 spin state assuming g = 2.00. This feature further indicates that the existence of overall antiferromagnetic coupling between the Fe(III) and Mn(III) ions. The magnetic property for 1 is different from those of cyanide-bridged FeIIIMnIIIFeIII trinuclar and FeIIIMnIII binuclear complexes based on a series of manganese(III)-porphyrins and cyanide-containing [Fe(L)(CN)2]− or [Fe(CN)6]3 − building blocks [24,26]. The magnetic properties of complex 2 are shown in Fig. 3. At room temperature, the χmT value is 3.57 emu K mol − 1. With decreasing the temperature, the χmT value keep nearly constant until about 20.0 K, then decreases quickly to 2.23 emu K mol − 1 at 2 K due to the intermolecular antiferromagnetic interaction and the zero-field splitting effect of magnetic anisotropic Mn(III) ion. The magnetic susceptibilities of complex 2 in the whole temperature range obeys
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G.-L. Li et al. / Inorganic Chemistry Communications 19 (2012) 66–69
Curie–Weiss law with small negative Weiss constant θ = – 0.71 K and Curie constant C = 3.58 emu K mol − 1. The difference for the magnetic susceptibilities of complexes 1 and 2 is due to there is antiferromagnetic coupling between Mn(III) and Fe(III) through cyanide bridge in complex 1. In order to evaluate the strength of intra-/inter-dimer magnetic coupling (J/zJ′) and zfs parameter (D) of Mn(III), the best fit for the ^ ¼ −2J S^Fe ⋅S^Mn þ experimental magnetic data above 25 K based on H ^ DMn S^2z − SMn ðS3Mn þ1Þ þ gbHS−zJ’ S^Tz S^Tz [22] (the fitting equation see Supporting Information), giving the fitting parameters J = –2.52(1) cm − 1, g = 1.99(1), DMn = 1.52(3) cm − 1, zJ’ = –0.14(3) cm − 1, and R = Σ[(χmT)obsd. − (χmT)calcd.] 2/Σ[(χmT) 2obsd.] = 5.22 × 10 − 5. It should be mentioned it is difficult to determine the sign of DMn based on the powder magnetic susceptibility data. The calculated DMn value (1.52 cm − 1) is normal for high-spin tetragonally elongated octahedral Mn(III) [22]. In addition, DMn and zJ′ are often correlated, and they should be treated with care. Complex 2 is a good model for the magnetic properties of Mn(III) compounds. The can be considered as isolated Mn(III) and Fe(III) ions, if the zero-field splitting (zfs) of the Mn(III) ion is considered. The best fit to the magnetic data in the whole temperature range using the expressions (see Supporting Information) on basis of 2 2 χ ionpair ¼ χ Mn þ χ Fe ¼ χ zfs þ χ Fe ¼ ð2χ ⊥ þ χ ∥ Þ=3 þ Ng3kTβ SFe ðSFe þ 1Þ gives the parameters g = 2.03(1), |DMn| = 3.5(2) cm − 1, zJ’ = −0.16(2) cm − 1 and R = 4.28 × 10 − 6. The results are similar to those of complex [Co(bpmb)(CN)2]6[Mn(5-Brsalpn)]6·12H2O [23]. In summary, two Fe III–Mn III complexes have been obtained based on manganese(III)-porphyrin and tetracyanideferrite(III) building blocks. Complex 1 shows cyanide-bridged Fe III–Mn III binuclear molecular structure, whereas complex 2 is an ion-pair compound. Magnetic investigation reveals the occurrence of overall weak antifferomagnetic coupling in the cyanide-bridged binuclear complex. This work further illustrates that manganese(III)-porphyrin and it's derivatives can be employed to assemble molecular magnetic complex and the molecular structures of them can be tuned by the peripheral substituted groups attached to the porphyrin precursor.
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Acknowledgements
[17]
This work was supported by the Nation Natural Science Foundation of China (No. 21176246), the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Fundamental Research Funds for the Central Universities (China University of Mining and Technology).
[18]
Appendix A. Supplementary material The supramolecular structures of compounds 1 and 2, and the magnetic properties of complex 2 can be found in Supporting Information file. Crystallographic data for the structure of complex 1 and 2 in this paper have been deposited at the Cambridge Crystallographic Data Center (CCDC 855982 for 1 and 855983 for 2). This information can be obtained free of charge at www.ccdc.cam.ac.uk/conts/ retrieving.html or from the Cambridge Crystallographic Data Centre (CCDC), 12 Union Road, Cambridge CB2 1EZ, United Kingdom; Fax: +44(0)1223-336033; e-mail: [email protected]. Supplementary data to this article can be found online at doi:10.1016/j.inoche. 2012.02.012. References [1] (a) R. Lescouëzec, M.L. Toma, J. Vaissermann, M. Verdaguer, F.S. Delgado, C. RuizPérez, F. Lloret, M. Julve, Design of single chain magnets through cyanidebearing six-coordinate complexes, Coord. Chem. Rev. 249 (2005) 2691–2729;
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Kou, Supramolecular metallomacrocycles based on trans-dicyanoferrite(III) building blocks: synthesis, crystal structure and magnetic properties, Dalton Trans. (2009) 2788–2794. Z.-H. Ni, L.-F. Zhang, A.-L. Cui, H.-Z. Kou, Synthesis, crystal structures and magnetic properties of cyanide-bridged macrocyclic complexes, Sci. China Ser. B–Chem. 52 (2009) 1444–1450. D.-P. Zhang, H.-L. Wang, L.-J. Tian, H.-Z. Kou, J.-Z. Jiang, Z.-H. Ni, Synthesis, crystal structures, and magnetic properties of cyanide-bridged Fe(III)–Mn(III) complexes based on manganese(III)-porphyrin and pyridinecarboxamide dicyanideiron(III) building blocks, Cryst. Growth Des. 9 (2009) 3989–3996. Crystal data for 1: C60H44FeMnN10O2, Mw = 1047.84, T = 123 K, triclinic, space group P1, a = 9.3108(19), b = 11.883(2), c = 12.098(2) Å, V = 1254.2(4) Å3, Z = 1, ρcalcd = 1.387 g cm− 3, μ = 0.597 mm− 1, λ(Mo Kα) = 0.71073 Å, F(000) = 541, 17258 measured reflections, 8773 unique reflections, 7850 observed reflections (I > 2σ(I)). R1 = 0.0384, wR2 = 0.0756(all data), GOF = 0.970 based on 366 parameters, largest difference peak and hole: 0.469/0.276 e Å− 3. Crystal date for 2: C64H46FeMnN16O10, Mw = 1309.96, T = 123 K, Monoclinic, space group C2/c, a = 15.261(3), b = 15.392(3), c = 25.217(5) Å, V = 5879(2) Å3, Z = 4, ρcalcd = 1.480 g cm− 3, μ = 0.538 mm− 1, λ(Mo Kα) = 0.71073 Å, F(000) =
G.-L. Li et al. / Inorganic Chemistry Communications 19 (2012) 66–69 2692, 18684 measured reflections, 5069 unique reflections, 3906 observed reflections (I > 2σ(I)). R1 = 0.0657, wR2 = 0.1547(all data), GOF = 0.987 based on 366 parameters, largest difference peak and hole: 0.942/− 0.521 e Å− 3. The structures of the two complexes were solved by the direct method and refined by full matrix least-squares on F2. Anisotropic thermal parameters were used
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for the non-hydrogen atoms. The hydrogen atoms attached to C and N atoms were added geometrically and refined using a riding model. [26] S. Huh, K.-T. Youm, Y.J. Park, A.J. Lough, M. Ohba, M.-J. Jun, Trinuclear MnIII–NC– FeIII–CN–MnIII ferromagnetic system, Bull. Korean Chem. Soc. 26 (2006) 1031–1302.