A Discrete μ4-Oxido Tetranuclear Iron(III) Cluster

FULL PAPER DOI: 10.1002/ejic.201200396

A Discrete μ4-Oxido Tetranuclear Iron(III) Cluster Manas Sutradhar,[a] Luca M. Carrella,[a] and Eva Rentschler*[a] Keywords: Tetranuclear Iron(III) / Schiff bases / X-ray diffraction / Magnetic properties / Cluster compounds Reaction of a Schiff base ligand derived from salicyloyl hydrazide and diacetyl monooxime (H2L) with a triangular μ3-oxido-centered [Fe3(μ3-O)]7+ core yields a new tetranuclear iron(III) complex. FeIII4(μ4-O) crystallizes in the triclinic space group P1¯. Structural studies reveal that this tetranuclear iron(III) complex is a new structure type of an uncharged (alkoxido)(oxido)iron(III) cluster in which the four

iron(III) ions are located at the corners of a distorted tetrahedron. A study of the magnetic properties supports the presence of antiferromagnetic interactions through the central μ4oxido ion as well as the μ2-methoxy groups present, giving an an S = 0 ground state. Mössbauer spectroscopy confirms the presence of high-spin iron(III) ions in this complex.

Introduction

formed from acyl hydrazide derived Schiff base ligands. This is most probably due to the strong chelating effect of these ligands, which leads to the formation of stable mononuclear complexes in an octahedral coordination environment.[10] A survey of the literature reveals that the oxime moiety of the ligand has versatile coordinating behavior (Figure 1). It can coordinate either through a nitrogen (I) or an oxygen (II) atom, i.e. it can act as an ambidentate ligand.[11] It can build μ1,2(N,O) oximato-bridged (III) extended networks[12] or coordinate with both the oximato nitrogen and oxygen atom (IV).[13]

Polynuclear iron clusters play a decisive role in many research areas and have been actively investigated over the last decades. They play a great role as model complexes for biological systems e.g. for several nonheme metalloproteins such as hemerythrin,[1] ribonucleotide reductase,[2] methane monooxygenase[3] and also for the iron oxide/hydroxide core of the iron storage protein ferritin.[4] Moreover, highnuclear iron compounds with appropriate topologies may possess a large spin ground-state (S) value and large negative magnetic anisotropy, thus occasionally exhibiting single-molecule-magnet (SMM) behavior.[5] In biomineralization processes, a variety of (oxido)iron minerals such as magnetite, ferrihydrite, goethite etc. are formed,[6] and many other complexes with aesthetically pleasing structures and interesting magnetic properties have been reported.[7] Though this area has been well developed and has received much attention over the last two decades,[8] tetranuclear iron clusters having a discrete (μ4-oxido)iron core are rather limited in the literature.[9] Surprisingly, only one compound bearing a discrete FeIII4(μ4-O) unit has been reported possessing, however, a planar μ4-O core.[9e] The other four structurally characterized complexes are tetranuclear μ4-oxido compounds containing discrete FeII4(μ4-O) units with a tetrahedral (or distorted tetrahedral) arrangement of the iron atoms. One of these complexes contains a mixed-valent FeII,III4(μ4-O) unit, linked by phosphate groups. A large number of high-nuclearity iron clusters have been reported in the literature, synthesized by using carboxylates, alcoholbased chelate ligands and other N,O-donor ligands, but to date there are no reports of a high-nuclearity iron cluster [a] Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10–14, 55128 Mainz, Germany Fax: +49-6131-3922284 E-mail: [email protected] Eur. J. Inorg. Chem. 2012, 4273–4278

Figure 1. Possible coordination modes the of oxime moiety.

Herein, we report the synthesis and characterization of a new tetranuclear iron(III) complex 1 featuring a discrete FeIII4(μ4-O) core using an N,N,O-donor Schiff base ligand, H2L. A very efficient synthetic strategy has been employed to prepare the tetranuclear (μ4-oxido)FeIII complex from the trinuclear coordination compound [Fe3O(Piv)6(H2O)3]Piv containing the triangular oxido-centered [Fe3(μ3-O)]7+ core. It has to be noted that the resultant [Fe4(μ4-O)(OMe)2L4] complex is a new structure type of an overall uncharged (alkoxido)(oxido)iron(III) cluster. Magnetic susceptibility measurements and a Mössbauer study are reported in this work.

Results and Discussion The Schiff base ligand H2L and others of this type with different aroyl hydrazides and diacetyl monooxime have a

© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

4273

M. Sutradhar, L. M. Carrella, E. Rentschler

FULL PAPER typical coordinating behavior. A review of the literature on structurally characterized compounds with these kinds of ligands show that only the nitrogen atom of the oxime moiety coordinates to the metal center, and the oxygen atom does not take part in coordination in the majority of the complexes.[14] Possibly additional strong intra- or intermolecular hydrogen bonds are formed with other donor atoms or groups[15] by the hydrogen atom of the oxime OH group. However, to date, there is no report of a polynuclear complex with these ligands in the CCDC structure database. Reaction of simple metal salts under various experimental conditions only leads to mononuclear species as reported in the literature.[10] We therefore took advantage of our experience in the preparation of higher-nuclearity clusters[16] using the preformed oligonuclear basic carboxylate cluster [Fe3O(Piv)6(H2O)3]Piv as starting reagent to synthesize polynuclear complexes with the ligand H2L. As depicted in Scheme 1, most probably, the ligand in methanolic solution immediately coordinates by means of enolization with one of the FeIII centers of the [Fe3(μ3-O)]7+ species in a tridentate fashion, and the three free OH groups of the ligand further coordinate to the next FeIII center after deprotonation. Thus, the central oxygen atom of the precursor species is retained in the product and helps to build the tetranuclear (μ4-oxido)FeIII complex, [Fe4(μ4O)(μ2-OMe)L4]·H2O·7CH3OH (1·H2O·7CH3OH). The total charge of the complex is balanced by four dianionic ligands, one μ4-oxido ion and two μ2-methoxide ions.

Scheme 1. Possible coordination behavior of H2L. Mode (1) realized in this work, mode (2*) in compounds reported in the literature.[10] 4274

www.eurjic.org

Description of the Crystal Structure of [Fe4(μ4-O)(μ2-OMe)L4]·H2O·7CH3OH (1·H2O·7CH3OH) Complex 1·H2O·7CH3OH crystallizes as twin crystals in the triclinic space group P1¯ (Table 4). The molecular structure of 1 is presented in Figure 2, selected bond parameters are given in Tables 1 and 2. The structure consists of the tetranuclear [Fe4(μ4-O)]10+ core with the oxido ion O(1) being located at the centre of a distorted tetrahedron and the four FeIII ions, Fe(1), Fe(2), Fe(3) and Fe(4) located at the vertices of the distorted tetrahedron. The Fe···Fe distances span between 3.084 and 3.632 Å. Fe(1) and Fe(2), as well as Fe(3) and Fe(4), are connected by mutual sharing of the bridging oxime group of two different ligands. The two units, Fe(1)–Fe(2) and Fe(3)–Fe(4), are connected by the central O(1) ion and two methoxido oxygen atoms O(70) and O(72) to form a tetranuclear iron(III) cluster. The Fe– O–Fe bond angles are found between 98.6(1)° and 128.0(2)°, deviating significantly from the ideal tetrahedral angle of 109.5°. On closer inspection, two sides, Fe(1)/Fe(4) and Fe(2)/Fe(3), can be identified, which subtend significantly smaller angles of 98.6(1)° and 100.7(1)°, respectively. Both are affected by the presence of an additional bridging μ2-MeO group each of which shortens the Fe–Fe distance considerably. Also, the angles Fe(1)–O(1)–Fe(2) and Fe(3)– O(1)–Fe(4), for which an additional linking of the iron ions by two NO groups each is present, shows smaller values of 105.1(1)° and 105.8(2)°, respectively. In contrast, the remaining two sides of the tetrahedron are wider, leading to Fe–O–Fe angles of 120.6(2)° and 128.0(2)°. All FeIII centers have a distorted octahedral N2O4 coordination environment. The ligand coordinates meridionally by forming with two nitrogen atoms and one oxygen atom together with the central O(1) atom the base of the coordination octahedron,

Figure 2. Molecular structure and partial atom numbering scheme for complex 1, with thermal ellipsoids drawn at the 50 % probability level. Hydrogen atoms and solvent molecules are omitted for clarity.

© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Eur. J. Inorg. Chem. 2012, 4273–4278

A Discrete μ4-Oxido Tetranuclear Iron(III) Cluster

while the axial positions are occupied by two oxygen atoms from the oxime bridge of a second ligand and the other from the μ-MeO– bridge, respectively. Table 1. Selected distances [Å] in complex 1·H2O·7CH3OH. Fe(1)–O(1) Fe(1)–O(2) Fe(1)–O(35) Fe(1)–O(70) Fe(1)–N(12) Fe(1)–N(17) Fe(2)–O(1) Fe(2)–O(18) Fe(2)–O(19) Fe(2)–O(72) Fe(2)–N(29) Fe(2)–N(34)

2.029(3) 1.980(4) 1.983(4) 1.972(4) 2.087(4) 2.150(4) 2.000(4) 2.013(4) 1.999(4) 2.005(4) 2.097(4) 2.155(4)

Fe(3)–O(1) Fe(3)–O(36) Fe(3)–O(69) Fe(3)–O(72) Fe(3)–N(46) Fe(3)–N(51) Fe(4)–O(1) Fe(4)–O(52) Fe(4)–O(53) Fe(4)–O(70) Fe(4)–N(63) Fe(4)–N(68)

2.041(4) 2.016(4) 1.978(4) 1.974(4) 2.100(4) 2.157(4) 2.040(3) 1.964(4) 2.007(4) 1.959(4) 2.093(4) 2.151(4)

Table 2. Selected angles [°] in complex 1·H2O·7CH3OH. Fe(1)–O(1)–Fe(2) Fe(1)–O(1)–Fe(3) Fe(1)–O(1)–Fe(4) Fe(2)–O(1)–Fe(3) O(1)–Fe(1)–O(2) O(1)–Fe(1)–O(35) O(1)–Fe(1)–O(70) O(1)–Fe(1)–N(12) O(1)–Fe(1)–N(17) O(2)–Fe(1)–O(35) O(2)–Fe(1)–O(70) O(2)–Fe(1)–N(12) O(2)–Fe(1)–N(17) O(35)–Fe(1)–O(70) O(35)–Fe(1)–N(12) O(35)–Fe(1)–N(17) O(70)–Fe(1)–N(12) O(70)–Fe(1)–N(17) N(12)–Fe(1)–N(17) O(1)–Fe(2)–O(18) O(1)–Fe(2)–O(19) O(1)–Fe(2)–O(72) O(1)–Fe(2)–N(29) O(1)–Fe(2)–N(34) O(18)–Fe(2)–O(19) O(18)–Fe(2)–O(72) O(18)–Fe(2)–N(29) O(18)–Fe(2)–N(34) O(19)–Fe(2)–O(72) O(19)–Fe(2)–N(29) O(19)–Fe(2)–N(34) O(72)–Fe(2)–N(29) O(72)–Fe(2)–N(34) N(29)–Fe(2)–N(34)

105.14(17) 120.56(19) 98.56(12) 100.74(13) 126.11(16) 89.16(14) 78.45(13) 158.05(17) 86.02(16) 92.44(15) 96.34(16) 75.26(16) 147.77(16) 167.47(15) 95.35(16) 90.21(16) 95.51(16) 87.11(17) 72.52(17) 89.90(14) 127.40(15) 78.14(13) 155.62(17) 85.39(16) 90.92(16) 167.91(15) 99.65(17) 91.96(16) 94.92(16) 75.20(16) 147.10(16) 92.08(16) 88.88(17) 72.01(17)

Fe(2)–O(1)–Fe(4) Fe(3)–O(1)–Fe(4) Fe(1)–O(70)–Fe(4) Fe(2)–O(72)–Fe(3) O(1)–Fe(3)–O(36) O(1)–Fe(3)–O(69) O(1)–Fe(3)–O(72) O(1)–Fe(3)–N(46) O(1)–Fe(3)–N(51) O(36)–Fe(3)–O(69) O(36)–Fe(3)–O(72) O(36)–Fe(3)–N(46) O(36)–Fe(3)–N(51) O(69)–Fe(3)–O(72) O(69)–Fe(3)–N(46) O(69)–Fe(3)–N(51) O(72)–Fe(3)–N(46) O(72)–Fe(3)–N(51) N(46)–Fe(3)–N(51) O(1)–Fe(4)–O(52) O(1)–Fe(4)–O(53) O(1)–Fe(4)–O(70) O(1)–Fe(4)–N(63) O(1)–Fe(4)–N(68) O(52)–Fe(4)–O(53) O(52)–Fe(4)–O(70) O(52)–Fe(4)–N(63) O(52)–Fe(4)–N(68) O(53)–Fe(4)–O(70) O(53)–Fe(4)–N(63) O(53)–Fe(4)–N(68) O(70)–Fe(4)–N(63) O(70)–Fe(4)–N(68) N(63)–Fe(4)–N(68)

128.0(2) 105.81(17) 103.39(14) 102.95(13) 128.95(15) 87.02(14) 77.91(13) 154.83(16) 84.51(16) 91.60(15) 93.50(16) 74.69(16) 146.47(16) 163.91(14) 102.39(16) 92.65(16) 93.67(16) 91.51(17) 71.91(17) 89.61(14) 129.44(16) 78.48(13) 154.61(18) 83.12(16) 89.02(15) 167.42(15) 99.40(17) 92.04(16) 95.37(16) 74.78(17) 147.43(16) 93.13(16) 90.57(17) 72.94(17)

The FeIII ions are little shifted (within the range from 0.043 to 0.81 Å) upwards from the above-mentioned basal plane. The bond lengths around the FeIII centres viz. Fe–N, Fe–OMe and Fe–O are as expected for this type of N2O4 coordination.[17] An additional four intramolecular hydrogen bonds are formed between the phenol OH group of the ligand and the imine nitrogen atom attached to the enol carbonyl carbon atom. The presence of a solvent methanol molecule in the crystal structures gives rise to intermolecular hydrogen bonds. The donor–acceptor distances are given in Table 3. Eur. J. Inorg. Chem. 2012, 4273–4278

Table 3. Donor–acceptor distances [Å] of 1·H2O·7CH3OH. O27–H27···N28 O10–H10···N11 O44–H44···N45 O61–H61···N62 O83–H83···O89 O77–H77···O91 O79–H79···O81 O81–H81···O87 O85–H85···O89 O91–H91···O75 O87–H87···O77 O89–H89···O83

2.566(6) 2.606(6) 2.555(6) 2.612(7) 2.72(2) 2.698(11) 2.694(12) 2.683(11) 2.832(18) 2.722(11) 2.732(11) 2.72(2)

Magnetism Variable-temperature, solid-state, magnetic susceptibility (χM) measurements of complex 1 were performed on powdered microcrystalline samples over the temperature range of 2–300 K in an applied field of 1 T. The collected susceptibility data are plotted in χMT vs. T in Figure 3 as well as the simulation obtained by using the following Hamiltonian operator: ˆ = –2J1(Sˆ1Sˆ4 + Sˆ2Sˆ3) – 2J2(Sˆ1Sˆ2 + Sˆ3Sˆ4 + Sˆ1Sˆ3 + Sˆ2Sˆ4) H

Figure 3. Plot of χT vs. T for 1 for a microcrystalline sample measured in an applied field of 1 T.

The room-temperature value for 1 is 9.00 cm3 K mol–1 and hence considerably smaller than the expected value of 17.51 cm3 K mol–1 for four noninteracting high-spin FeIII ions. By lowering the temperature, a noteworthy decrease of the χMT value can be observed, reaching a value close to 0 cm3 K mol–1 at 2 K. This indicates an overall antiferromagnetically coupled system with an S = 0 ground state. The magnetic data can be simulated satisfactorily by applying the model depicted in Figure 3 with two different coupling constants. The coupling constant J1 describes the magnetic interaction through the μ4-oxido and μ2-methoxido bridge between Fe(1)–Fe(4) and Fe(2)–Fe(3), respectively. The magnetic exchange between Fe(1)–Fe(2), Fe(1)– Fe(3), Fe(2)–Fe(4) and Fe(3)–Fe(4) over the μ4-oxido bridge was taken into account by the constant J2. The best fit was obtained with J1 = –7.89 cm–1, J2 = –10.48 cm–1, g = 2.00 and a small paramagnetic contribution of 3.6 %. The differ-

© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org

4275

M. Sutradhar, L. M. Carrella, E. Rentschler

FULL PAPER ence in the strength of the coupling constants is consistent with the differences in the bridging angles observed for the central μ4-oxido ion. Larger Fe–O–Fe angles favor stronger antiferromagnetic exchange interactions, and this is well known from the literature.[18]

as how to build higher-nuclearity clusters with an aroyl hydrazide oxime ligand. Introducing different substituents at the aroyl hydrazide moiety could be interesting in order to change various physicochemical properties of the FeIII clusters.

Mössbauer Studies

Experimental Section

Figure 4 shows the Mössbauer spectrum of 1, which was recorded at room temperature. Only one quadrupole doublet can be observed, which reveals the electronic equivalence of all four iron ions. The values for the isomer shift δ of 0.399(12) mm s–1 and the quadrupole splitting ΔEQ of 1.050(22) mm s–1 are perfectly in agreement with the expected values for a six-coordinate high-spin FeIII ion.[19] The isomer shift is slightly smaller than the value reported for a square-planar (μ4-oxo)Fe4 complex,[9e] which reflects the N,N,O-coordination of the FeIII center in 1.

Materials and Methods: [Fe3(μ3-O)(Piv)6(H2O)3](Piv) [Piv = C(CH3)3COO–] was prepared as described in the literature.[20] All other chemicals were reagent grade, obtained from commercial sources and used without further purification. Spectroscopic grade solvents were used for spectroscopic measurements. Elemental analyses (C, H and N) were performed with a Foss Heraeus Vario EL elemental analyzer. Molecular weights and formulae were calculated without solvent molecules unless explicitly stated. Infrared spectra were recorded in the 400–4000 cm–1 range with a Jasco FTIR-4200 spectrometer. The measurements were carried out by using the pellet technique with KBr as the matrix. Magnetic susceptibility data of 1 were collected with a SQUID magnetometer (MPMS-7 Quantum Design). Experimental susceptibility data were corrected for the underlying diamagnetisms by using Pascal’s constants. The temperature-dependent magnetic contribution of the holder was experimentally determined and subtracted from the measured susceptibility data. The routine Clumag was used for spin Hamiltonian simulations of the data.[21] Mössbauer data were recorded with an alternating-current constant-acceleration spectrometer with a 57Co source (Rh matrix). The minimum experimental line width was 0.3 mm s–1 (full width at half-height). Isomer shifts are quoted relative to iron metal at 300 K. Syntheses

Figure 4. Mössbauer spectrum of 1 obtained at room temperature. The solid line represents the simulation of the data.

Conclusions The use of an aroyl hydrazide oxime ligand in general and salicyloyl hydrazide of diacetyl monooxime (H2L) in particular has been reported for the first time for synthesizing polynuclear FeIII clusters. Since the reaction of H2L with normal metal salts yields only mononuclear species, to synthesize polynuclear FeIII complexes we chose an oxidocentered [Fe3(μ3-O)]7+ metal salt as the precursor, and we successfully obtained the tetranuclear FeIII cluster with a discrete FeIII4(μ4-O) core. A structural study revealed that the FeIII complex is an uncharged (alkoxido)(oxido)iron(III) cluster and contains the rare example of a discrete FeIII4(μ4-O) core. The complex shows the characteristic feature of an antiferromagnetically coupled system with an S = 0 ground state. The exchange coupling takes place through the doubly bridged (μ-methoxido)(μ4-oxido) groups with J1 = –7.89 cm–1, J2 = –10.48 cm–1 and g = 2.00. The Mössbauer studies support the presence of high-spin FeIII ions, which are typical for 6-coordinate high-spin (μoxido)iron(III) species. Finally, this works shows new ideas 4276

www.eurjic.org

H2L: The Schiff base ligand, salicyloyl hydrazide of diacetyl monooxime was prepared by heating to reflux an equimolar mixture of diacetyl monooxime and the salicyloyl hydrazide in a methanol medium according to a method reported in the literature.[10a,10b] [Fe4(μ4-O)(μ2-OMe)L4]·H2O·7CH3OH (1·H2O·7CH3OH): To a methanolic suspension (30 mL) of ligand H2L (0.352 g, 1.5 mmol) was added a methanolic solution (30 mL) of [Fe3(μ3-O)(Piv)6(H2O)3](Piv) (0.473 g, 0.5 mmol), and the resultant mixture was stirred at room temperature for 15 min. The reddish-brown solution slowly turned dark-brown. The mixture was then filtered, and the solvent was allowed to slowly evaporate. After 2–3 d, single crystals suitable for X-ray diffraction were isolated. Yield: 74 %. C46H50Fe4N12O15 (1234.36): calcd. C 44.76, H 4.08, N 13.62; found C 44.64, H 4.12, N 13.56. IR (KBr): ν˜ max = 3442 (OH), 1486 (C=N), 1254 (N–N) cm–1. X-ray Diffraction Analyses: A single crystal of 1 was coated with perfluoropolyether, picked up with a glass fiber, and mounted on a SMART APEX II CCD diffractometer equipped with a nitrogen cold stream operating at 173(2) K (Table 4). Graphite-monochromated Mo-Kα radiation (λ = 0.71069 Å) from a fine-focus sealed tube was used throughout. Cell constants were obtained from a least-squares fit of the diffraction angles of several thousand strong reflections. Data reduction was done with APEX2 v2.0,[22] while SIR-97 [23] and SHELXL-97[24] were used for the structure solution and for the refinement, respectively. An absorption correction was carried out by the semiempirical routine MULTISCAN implemented in the PLATON crystallographic software package. CCDC-876937 contains the supplementary crystallographic data

© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Eur. J. Inorg. Chem. 2012, 4273–4278

A Discrete μ4-Oxido Tetranuclear Iron(III) Cluster for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/ data_request/cif. Table 4. Crystal data and structure determination summary of complex 1·H2O·7CH3OH. Empirical formula Formula mass Crystal system Space group a [Å] b [Å] c [Å] α [°] β [°] γ [°] V [Å3] Z Dcalcd. [g cm–3] Data/parameters/restraints Reflections with I ⬎ 2σ(I) R1 [I ⬎ 2σ(I), all data][a] wR2 [I ⬎ 2σ(I), all data][b] GOOF Max. diff. peak/hole [e Å–3]

C53H80Fe4N12O23 1466.61 triclinic P1¯ 13.0215(7) 17.0437(10) 17.5516(10) 67.146(2) 86.909(2) 80.076(2) 3535.4(3) 2 1.378 17068/864/1 12166 0.0676, 0.1101 0.1334, 0.1520 1.062 –0.62–0.74

[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|. [b] wR2 = [Σw(Fo2 – Fc2)2/Σw(Fo2)2]1/2.

Acknowledgments M. S. is grateful to the Deutscher Akademischer Austausch Dienst (DAAD), Germany for the award of a postdoctoral research fellowship. [1] a) P. C. Wilkins, R. G. Wilkins, Coord. Chem. Rev. 1987, 79, 195–214; b) R. A. Friesner, M.-H. Baik, B. F. Gherman, V. Guallar, M. Wirstam, R. B. Murphy, S. J. Lippard, Coord. Chem. Rev. 2003, 238–239, 267–290; c) D. M. Kurtz, Compr. Coord. Chem. II 2003, 8, 229–260 [2] a) P. Nordlund, B. M. Sjoberg, H. Eklund, Nature 1990, 345, 593–598; b) B. A. Averill, J. C. Davis, S. Bruma, T. Zirino, J. Sanderts-Loehr, T. M. Loehr, J. T. Sage, P. G. Debrunner, J. Am. Chem. Soc. 1987, 109, 3760–3767; c) E. Mulliez, M. Fontecave, Coord. Chem. Rev. 1999, 185–186, 775–793; d) L. Que Jr., J. Chem. Soc., Dalton Trans. 1997, 3933–3940. [3] a) B. G. Fox, K. K. Surerus, E. Munck, J. D. Lipscomb, J. Biol. Chem. 1988, 263, 10553–10556; b) A. Ericson, B. Hedman, K. O. Hodgson, J. Green, H. Dalton, J. G. Bentsen, R. H. Gbeer, S. J. Lippard, J. Am. Chem. Soc. 1988, 110, 2330–2332; c) S. Friedle, E. Reisner, S. J. Lippard, Chem. Soc. Rev. 2010, 39, 2768–2779; d) I. Siewert, C. Limberg, Chem. Eur. J. 2009, 15, 10316–10328. [4] a) E. C. Theil, Annu. Rev. Biochem. 1987, 56, 289–315 and references cited therein; b) S. J. Lippard, Angew. Chem. 1988, 100, 353; Angew. Chem. Int. Ed. Engl. 1988, 27, 344–361; c) G. S. Waldo, E. C. Theil, Compr. Supramol. Chem. 1996, 5, 65–89; d) E. C. Theil, X.-S. Liu, M. Matzapetakis, Metal Ions Life Sci. 2008, 4, 327–341 [5] a) T. Taguchi, T. C. Stamatatos, K. A. Abboud, C. M. Jones, K. M. Poole, T. A. O’Brien, G. Christou, Inorg. Chem. 2008, 47, 4095–4108; b) A. K. Boudalis, N. Lalioti, G. A. Spyroulias, C. P. Raptopoulou, A. Terzis, A. Bousseksou, V. Tangoulis, J. P. Tuchagues, S. P. Perlepes, Inorg. Chem. 2002, 41, 6474–6487; c) A. L. Barra, A. Caneschi, A. Cornia, F. F. de Biani, D. Gatteschi, C. Sangregorio, R. Sessoli, L. Sorace, J. Am. Chem. Soc. 1999, 121, 5302–5310; d) H. Oshio, N. Hoshino, T. Ito, J. Am. Chem. Soc. 2000, 122, 12602–12603. Eur. J. Inorg. Chem. 2012, 4273–4278

[6] S. Mann, J. Webb, R. J. P. Williams (Eds.), Biomineralization: Chemical and Biochemical Perspectives, VCH, New York, 1988. [7] a) K. Wieghardt, K. Pohl, I. Jibril, G. Huttner, Angew. Chem. 1984, 96, 66; Angew. Chem. Int. Ed. Engl. 1984, 23, 77–78; b) S. M. Gorun, G. C. Papaefthymiou, R. B. Frankel, S. J. Lippard, J. Am. Chem. Soc. 1987, 109, 3337–3348; c) W. Micklitz, V. McKee, R. L. Rardin, L. E. Pence, G. C. Papaefthymious, S. G. Bott, S. J. Lippard, J. Am. Chem. Soc. 1994, 116, 8061– 8069; d) J. K. McCusker, C. A. Christmas, P. M. Hagen, R. K. Chadha, D. F. Harvey, D. N. Hendrickson, J. Am. Chem. Soc. 1991, 113, 6114–6124; e) K. L. Taft, S. J. Lippard, J. Am. Chem. Soc. 1990, 112, 9629–9630; f) S. P. Watton, P. Fuhrmann, L. E. Pence, A. Caneschi, A. Cornia, G. L. Abbati, S. J. Lippard, Angew. Chem. 1997, 109, 2917; Angew. Chem. Int. Ed. Engl. 1997, 36, 2774–2776; g) C. Benelli, S. Parsons, G. A. Solan, R. E. P. Winpenny, Angew. Chem. 1996, 108, 1967; Angew. Chem. Int. Ed. Engl. 1996, 35, 1825–1828; h) K. Hegetschweiler, H. Schmalle, H. M. Streit, W. Schneider, Inorg. Chem. 1990, 29, 3625–3627; i) C. M. Grant, M. J. Knapp, W. E. Streib, J. C. Huffman, D. N. Hendrickson, G. Christou, Inorg. Chem. 1998, 37, 6065–6070; j) L. F. Jones, E. K. Brechin, D. Collison, M. Helliwell, T. Mallah, S. Piligkos, G. Rajaraman, W. Wernsdorfer, Inorg. Chem. 2003, 42, 6601–6603; k) A. Masello, Y. Sanakis, A. K. Boudalis, K. A. Abboud, G. Christou, Inorg. Chem. 2011, 50, 5646–5654. [8] a) Q. T. Islam, D. E. Sayers, S. M. Gorun, E. C. Theil, J. Inorg. Biochem. 1989, 36, 51–62; b) K. L. Taft, G. Papaefthymiou, S. J. Lippard, Inorg. Chem. 1994, 33, 1510–1520; c) A. K. Powell, S. L. Heath, D. Gatteschi, L. Pardi, R. Sessoli, G. Spina, F. D. Giallo, F. Pieralli, J. Am. Chem. Soc. 1995, 117, 2491– 2502; d) D. Gatteschi, A. Caneschi, R. Sessoli, A. Cornia, Chem. Soc. Rev. 1996, 25, 101–109; e) D. Gatteschi, R. Sessoli, A. Cornia, Chem. Commun. 2000, 725–732; f) T. Schneppensieper, G. Liehr, R. van Eldik, J. Ensling, P. Gütlich, Inorg. Chem. 2000, 39, 5565–5568; g) C. Benelli, J. Cano, Y. Journaux, R. Sessoli, G. A. Solan, R. E. P. Winpenny, Inorg. Chem. 2001, 40, 188–189. [9] a) F. A. Cotton, L. M. Daniels, L. R. Falvello, J. H. Matonic, C. A. Murillo, X. Wang, H. Zhou, Inorg. Chim. Acta 1997, 266, 91–102; b) F. A. Cotton, L. M. Daniels, G. T. Jordan, C. A. Murillo, I. Pascual, Inorg. Chim. Acta 2000, 297, 6–10; c) F. F. Jian, H. L. Xiao, Z. S. Bai, P. Zhao, J. Mater. Chem. 2006, 16, 3746–3752; d) J. R. D. DeBord, W. M. Reiff, C. J. Warren, R. C. Haushalter, J. Zubieta, Chem. Mater. 1997, 9, 1994–1998; e) M. Murali, S. Nayak, J. S. Costa, J. Ribas, I. Mutikainen, U. Turpeinen, M. Clemancey, R. Garcia-Serres, J. Latour, P. Gamez, G. Blondin, J. Reedijk, Inorg. Chem. 2010, 49, 2427– 2434; f) A. Malassa, B. Schulze, B. Stein-Schaller, H. Görls, B. Weber, M. Westerhausen, Eur. J. Inorg. Chem. 2011, 1584–1592. [10] a) S. Naskar, D. Mishra, R. J. Butcher, S. K. Chattopadhyay, Polyhedron 2007, 26, 3703–3714; b) Z.-J. Xiao, S.-X. Liu, C.C. Lin, Chinese J. Inorg. Chem. 2004, 20, 513–518; c) N. Chitrapriya, V. Mahalingam, M. Zeller, K. Natarajan, Inorg. Chim. Acta 2010, 363, 3685–3693; d) S. P. Dash, S. Pasayat, Saswati, H. R. Dash, S. Das, R. J. Butcher, R. Dinda, Polyhedron 2012, 31, 524–29. [11] A. Chakravorty, Coord. Chem. Rev. 1974, 13, 1–46. [12] a) S. Sreerama, S. Pal, Inorg. Chem. 2002, 41, 4843–4845; b) S. Ross, T. Weyhermüller, E. Bill, E. Bothe, U. Flörke, K. Wieghardt, P. Chaudhuri, Eur. J. Inorg. Chem. 2004, 984–997; c) S. Wan, W. Mori, S. Yamada, S.-I. Murahashi, Bull. Chem. Soc. Jpn. 1989, 62, 435–438. [13] a) P. Chaudhuri, Coord. Chem. Rev. 2003, 243, 143; b) V. Sharma, V. Sharma, R. Bohra, Transition Met. Chem. 2007, 32, 442–448; c) V. Sharma, V. Sharma, R. Bohra, J. E. Drake, M. B. Hursthouse, M. E. Light, Inorg. Chim. Acta 2007, 360, 2009–2015. [14] a) J. Korvenranta, H. Saarinen, M. Näsäkkälä, Inorg. Chem. 1982, 21, 4296–4300; b) J. G. Mohanty, R. P. Singh, A. Chakravorty, Inorg. Chem. 1975, 14, 2178–2183; c) A. N. Singh, R. P.

© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.eurjic.org

4277

M. Sutradhar, L. M. Carrella, E. Rentschler

FULL PAPER Singh, J. G. Mohanty, A. Chakravorty, Inorg. Chem. 1977, 16, 2597–2601; d) J. G. Mohanty, A. Chakravorty, Inorg. Chem. 1976, 15, 2912–2916; e) A. G. Lappin, M. C. M. Laranjeira, R. D. Peacock, Inorg. Chem. 1983, 22, 786–791. [15] a) V. Yu. Kukushkin, T. Nishioka, T. Tudela, K. Isobe, I. Kinoshita, Inorg. Chem. 1997, 36, 6157–6165; b) R. J. Butcher, R. S. Bendre, A. S. Kuwar, Acta Crystallogr., Sect. E 2005, 61, 3511– 3513. [16] P. Albores, E. Rentschler, Dalton Trans. 2010, 39, 5005. [17] a) I. A. Gass, C. J. Milios, A. G. Whittaker, F. P. A. Fabiani, S. Parsons, M. Murrie, S. P. Perlepes, E. K. Brechin, Inorg. Chem. 2006, 45, 5281–5283; b) R. Shaw, R. H. Laye, L. F. Jones, D. M. Low, C. Talbot-Eeckelaers, Q. Wei, C. J. Milios, S. Teat, M. Helliwell, J. Raftery, M. Evangelisti, M. Affronte, D. Collison, E. K. Brechin, E. J. L. McInnes, Inorg. Chem. 2007, 46, 4968–4978; c) K. Hegetschweiler, H. W. Schmalle, H. M. Streit, V. Gramlich, H. U. Hund, I. Erni, Inorg. Chem. 1992, 31, 1299– 1302.

4278

www.eurjic.org

[18] a) H. Weihe, H. U. Güdel, J. Am. Chem. Soc. 1997, 119, 6539– 6543; b) H. Weihe, H. U. Güdel, J. Am. Chem. Soc. 1998, 120, 2870–2879. [19] P. Gütlich, E. Bill, A. X. Trautwein, Mössbauer Spectroscopy and Transition Metal Chemistry: Fundamentals and Applications, Springer Verlag, Berlin, Heidelberg, 2011, p. 120ff. [20] M. A. Kiskin, I. G. Fomina, A. A. Sidorov, G. G. Aleksandrov, O. Yu. Proshenkina, Zh. V. Dobrokhotova, V. I. Ikorskii, Yu. V. Shvedenkov, V. M. Novotortsev, I. L. Eremenko, I. I. Moiseev, Russ. Chem. Bull. I. E. 2004, 53, 2508–2518. [21] D. Gatteschi, L. Pardi, Gazz. Chim. Ital. 1993, 123, 231–240. [22] APEX2 Software Suite, version 2.0, Bruker, 2005. [23] A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori, R. Spagna, J. Appl. Crystallogr. 1999, 32, 115–119. [24] G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112–122. Received: April 19, 2012 Published Online: August 14, 2012

© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Eur. J. Inorg. Chem. 2012, 4273–4278