Two Heterometallic Aggregates Constructed from the {P2W12}-Based

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DOI: 10.1021/cg900745z

Two Heterometallic Aggregates Constructed from the {P2W12}-Based Trimeric Polyoxotungstates and 3d-4f Heterometals

2010, Vol. 10 135–139

Shuang Yao, Zhiming Zhang, Yangguang Li,* Ying Lu, Enbo Wang,* and Zhongmin Su* Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Renmin Street No. 5268, Changchun, Jinlin, 130024, P. R. China Received July 2, 2009; Revised Manuscript Received October 21, 2009

ABSTRACT: Reactions of hexavacant polyoxotungstate [H2P2W12O48]12- ({P2W12}) with transition-metal and lanthanidemetal cations assisted with organic molecules (tartrate or dimethylammonium chloride) lead to the isolation of two polyoxotungstates: K3Na8[K3⊂{GdMn(H2O)10}{HMnGd2(Tart)O2(H2O)15}{P6W42O151(H2O)7}] 3 44H2O (1) and K3Na10[K3⊂{GdCo(H2O)11}2{P6W41O148(H2O)7}] 3 43H2O (2). Single-crystal X-ray diffraction analyses reveal that both 1 and 2 contain a crown-type polyoxoanion shell [{WO(H2O)}3(P2W12O48)3]30- ({P6W39}), which consists of three {P2W12} units connected by three {WO(H2O)} linkers. Compound 1 has a two-dimensional porous framework constructed from 3d-4f clustercontaining {P6W39} aggregates and mixed 3d and 4f linkers. Compound 2 exhibits a one-dimensional chain-like structure composed of di-Co-containing {P6W39} aggregates and {Gd(H2O)7}3þ bridging units. Magnetic studies of compounds 1 and 2 indicate that antiferromagnetic interactions exist in these two compounds.

Introduction Polyoxometalates (POMs), due to their versatile structural topologies, nucleophilic oxygen-enriched surfaces and high negative charges, can be viewed as one kind of excellent inorganic multidentate O-donor ligand to design and synthesize new polynuclear transition-metal (TM) or lanthanidemetal (Ln) substituted magnetic aggregates.1,2 In this field, lacunary POMs are one of the ideal building blocks.3-6 During their preparation, they usually display a strong potential for incorporating paramagnetic metal centers into magnetic POM aggregates, such as the {V12} aggregate, {Cu20} cluster, {Cu20-azide} cluster, {Fe16} cluster, {Co10} and Lncontaining polyoxoanions based on the crown {P8W48} tetramer,3 as well as the high-nuclear Mn-, Fe-, Co-, Ni-, and Cu-cluster-containing compounds based on the lacunary Keggin POM ligands.4,5 Studies have shown that magnetic POMs can exhibit single-molecule magnet behavior.4a,4b Simultaneously, a more recent advance in the synthesis of paramagnetic metal aggregates has focused on the design and synthesis of 3d-4f or 4d-4f heterometallic systems, attributed to their exploitable applications in magnetism, bimetallic catalysis, and molecular adsorption, as well as their intriguing architectures and topologies.7-10 However, only a few 3d-4f heterometallic compounds have been reported up to now. In the reaction, oxyphilic Ln cations usually possess high reactivity with POMs, leading to precipitation instead of crystallization. Furthermore, the reactive activity between the polyoxoanions and TM ions is relatively weak. So reaction competition unavoidably exists among the highly negative polyoxoanions, strongly oxyphilic Ln cations, and relatively less active TM cations in aqueous solution systems. These have made it difficult to synthesize POM-based heterometallic aggregates. Interestingly, K€ ogerler et al. recently reported two heterometallic POMs by reactions of the lacunary polyoxoanions with

the preformed heterometallic clusters [CeIV3MnIV2O6(OH)2]6þ and [CeMn6O9(O2CCH3)9(NO3)(H2O)2], which have successfully avoided competition among the highly negative polyoxoanions, Ln cations, and TM cations.7 Very recently, Mialane0 s group reported the magnetic {LnCu3(OH)3(O(W))} cubane units-containing POMs by reaction of the [A-R-SiW9O34]10unit with the CuII acetate, Ln(NO3)3 in the presence of adapted exogenous ligands.8 We have even synthesized several POM-based compounds containing 3d and 4f metal ions.9 During the investigation, it is found that some adapted organic ligands in the reaction mixture of POM/TM/Ln play important roles in the synthesis of new 3d-4f heterometallic aggregates.8,9 On the basis of aforementioned points, TM cations, Ln cations, and some adapted organic ligands were introduced into the high lacunary {P2W12} system, resulting in two 3d-4f heterometallic aggregates K3Na8[K3⊂{GdMn(H2O)10}{HMnGd2(Tart)O2(H2O)15}{P6W42O151(H2O)7}] 3 44H2O (1) and K3Na10[K3⊂{GdCo(H2O)11}2{P6W41O148(H2O)7}] 3 43H2O (2). In 1, both TM and Ln cations are encapsulated in the cavity of the crown-type {P6W39} with assistance of secondary tartrate ligands. Further, the crown-type polyoxoanions in 1 are connected into a two-dimensional (2-D) porous framework by Gd3þ and Mn2þ linkers, which has been observed for the first time in POM chemistry. For 2, the Co-containing crown-type polyoxoanions were linked by Gd3þ ions into a one-dimensional (1-D) chain. Experimental Section

*To whom correspondence should be addressed. E-mail: wangeb889@ nenu.edu.cn (E.B.W.), [email protected] (Y.G.L.), [email protected] (Z.M.S.). Fax: þ86- 431-85098787.

Materials and Methods. All chemicals were commercially purchased and used without further purification. K12[H2P2W12O48] 3 24H2O was synthesized according to the literature11 and characterized by IR spectrum. Elemental analysis for C was performed on a Perkin-Elmer 2400 CHN Elemental analyzer. W, P, Co, Mn, Gd, K, and Na were determined by a Leaman inductively coupled plasma (ICP) spectrometer. IR spectra were recorded in the range 400-4000 cm-1 on an Alpha Centaurt FT/IR spectrophotometer using KBr pellets. TG analyses were performed on a Perkin-Elmer TGA7 instrument in flowing N2 with a heating rate of 10 °C 3 min-1. Magnetic susceptibilities were measured on finely grounded single

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Crystal Growth & Design, Vol. 10, No. 1, 2010

Results and Discussion Synthesis. As is well-known, the hexavacant derivative of the Wells-Dawson polyoxoanion {P2W12} is an excellent building block for the construction of new nanoscale aggregates.3,13,14 In this work, we have tried to introduce TM and Ln ions into the {P2W12} system so as to obtain new 3d-4f heterometallic aggregates. However, the highly oxyphilic Ln ions usually possess high reactivity with polyoxoanions, always leading to precipitation instead of crystallization.15 Further, the reaction between the polyoxoanions and TM ions is less active; thus, the reaction competition will

Table 1. Crystal Data and Structure Refinement for 1-2 1

2

H144K6Na10Co2C4H155Na8K6Gd3Mn2O235P6W42 Gd2O221P6W41 M 12871.95 12301.68 λ/A˚ 0.71073 0.71073 T/K 150(2) 150(2) crystal size/mm 0.24  0.13  0.12 0.27  0.14  0.11 crystal system triclinic triclinic P1 space group P1 a/A˚ 19.460(4) 21.041(4) b/A˚ 20.323(4) 23.295(5) c/A˚ 31.407(6) 26.343(5) R/° 95.59(3) 74.49(3) β/° 90.01(3) 79.05(3) γ/° 108.96(3) 67.13(3) 11684(4) 11409(4) V/A˚3 Z 2 2 3.659 3.581 Dc/Mg m-3 -1 21.800 21.568 μ/mm F(000) 11684 10884 θ range/° 3.00 - 25.00 3.03 - 25.00 data/restraints/parameters 38912/20/1492 36496/6/1403 0.0802 0.0816 R1 (I > 2σ(I ))a a 0.1918 0.1947 wR2 (all data) 0.944 0.933 goodness-of-fit on F2 P P P P a R1 = F0| - |FC / |F0|; wR2 = [w(F02 - FC2)2]/ [w(F02)2]1/2. empirical formula

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crystal samples (grease restricted) with the use of a Quantum Design SQUID magnetometer MPMS-XL. Synthesis of 1. Freshly prepared K12[H2P2W12O48] 3 24H2O (1.5 g, 0.38 mmol) was dissolved in 50 mL of distilled water. Then, 30 mL of 0.015 M Gd(NO3)3 aqueous solution (0.45 mmol containing 0.5 g of racemic sodium tartrate dibasic dihydrate) and 9 mL of 1 M MnCl2 aqueous solution (9 mmol) were added to the mixture with vigorous stirring. The final mixture was kept at 40 °C for 3 h with vigorous stirring. After being cooled to room temperature, the solution was filtered and the filtrate was kept at room temperature for slow evaporation. Yellow block crystals of 1 were isolated after five weeks (yield 43% based on P). Anal. found (%): C, 0.47; K, 1.92; Na, 1.76; Mn, 0.97; Gd, 3.87; P, 1.66; W, 60.10; Calcd: C, 0.38; K, 1.81; Na, 1.53; Mn, 0.86; Gd, 3.64; P, 1.44; W, 59.89. IR (KBr pellet): 1143(w), 1084(w), 1023(w), 928(m), 869(m), 783(m), 763(s), and 523 cm-1(m). Characteristic UV-bands: 207 and 262 nm. TG loss of water and the tartrate ligand from 30 to 423 °C, experimental (Calcd): 12.01% (11.96%). Synthesis of 2. Freshly prepared K12[H2P2W12O48] 3 24H2O (1.5 g, 0.38 mmol) was dissolved in 50 mL of distilled water. Then, 9 mL of 1 M CoCl2 aqueous solution (9 mmol) and 20 mL of 0.015 M Gd(NO3)3 aqueous solution (0.3 mmol, containing 1.0 g (CH3)2NH 3 HCl) were added to the mixture with vigorous stirring. Then, the resulting solution was stirred for 12 h at room temperature. After being cooling to room temperature, the solution was filtered and the filtrate was kept at room temperature for slow evaporation. Red block crystals of 2 were isolated for half a month (yield 55% based on P). Anal. found (%): K, 2.15; Na, 2.01; Co, 1.13; Gd, 2.26; P, 1.31; W, 61.29; Calcd: K, 1.90; Na, 1.89; Co, 0.96; Gd, 2.57; P, 1.50; W, 61.46. IR (KBr pellet): 1144(m), 1043(m), 1085(m), 1026(m), 935(s), 784(s), 666(s), 516(s), and 451 cm-1(s). Characteristic UVbands: 207 and 261 nm. TG water loss from 40 to 419 °C, experimental (Calcd): 10.59% (10.54%). X-ray Crystallography. The measurements were performed on a Rigaku R-AXIS RAPID IP diffractometer. Data collection was performed at 150(2) K with graphite-monochromated MoKR radiation (λ = 0.71073 A˚). Suitable crystals were affixed to the end of a glass fiber using silicone grease and transferred to the goniostat. The structures were solved by the direct method and refined by the full-matrix least-squares method on F2 using the SHELXTL-97 crystallographic software package.12 During the refinement, there were a number of short connections between Ow(water) 3 3 3 O(POM) in the range of 2.50-2.90 A˚, suggesting the extensive H-bonding interactions between lattice water molecules and the POMs. All H atoms on water molecules were directly included in the molecular formula. Hydrogen atoms of organic ligands were fixed in the calculated positions. In the two compounds, only partial lattice water molecules can be accurately assigned from the residual electron peaks, while the rest were directly included in the molecular formula based on the elemental analyses and TG analyses. A summary of crystal data and structure refinements for compounds 1 and 2 is provided in Table 1. CCDC-713622 contains the supplementary crystallographic data for compound 1. The data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Further details of the crystal structure investigations for 2 can be obtained from the Fachinformationszentrum Karlsruhe, 76344 EggensteinLeopoldshafen, Germany (fax: (þ49)7247-808-666; e-mail: [email protected]) by quoting the depository number CSD420191 (2).

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unavoidably exist among the highly negative polyoxoanions, strongly oxyphilic Ln cations, and TM cations in such a mixed reaction system.9 It is still a current challenge to explore suitable synthetic conditions to obtain new POMbased 3d-4f heterometallic aggregates. In this paper, some adapted organic ligands tartrate and dimethylammonium chloride were introduced into the reaction mixture of {P2W12}, TM cations, and Ln cations, resulting in two new 3d-4f heterometallic complexes based on the crown-type {P6W39}. It can be concluded that the use of secondary organic ligands might stabilize the Ln ions and/or reduce the reactivity of Ln ions with polyoxoanions. It is noteworthy that we have tried constructing the POMbased 3d-4f heterometallic aggregates by using {P6W39} as the starting material. Unfortunatley, the {P6W39} shell could not be obtained in the absence of the TM and Ln cations after several months of attempts. So we systemically explored the experimental conditions for the in situ reaction of the {P2W12} with TM and Ln cations, in order to provide some useful information for synthesizing trimeric crown-type {P2W12}-based compounds. Structure Description. Single-crystal X-ray diffraction analyses (Table 1) confirm that both compounds 1 and 2 contain a crown-type trimeric cluster {P6W39} (Scheme 1d). This {P6W39} shell consists of three {P2W12} subunits linked by three {WO(H2O)} fragments in a corner-sharing mode (Scheme S1, Supporting Information). In this crown, the three W atoms in the hinges are all in a hexa-coordinated environment completed by four oxo atoms derived from two adjacent {P2W12} units, an isolated oxo atom, and an aqualigand. As shown in Scheme 1d,e, the external diameter of this crown is ca. 19.4 A˚ and the thickness is about 10.0 A˚. This aggregate contains a pumpkin-like inner cavity with the shortest and longest diameters of ca. 8.3 A˚ and ca. 10.5 A˚ (see Scheme 1f). In this {P6W39} shell, the angles between two {P2W12} subunits are about 60°, which are different from those of the tetrameric {P8W48} and dimeric {P4W24} clusters whose angles between two adjacent {P2W12} units are 90° and 36°, respectively (see Scheme 1a-c); however, the

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Scheme 1. Schematic View of {P2W12}-Based Crown- and Half-Crown-Type POMsa

a (a) Tetrameric {P8W48} displaying the angle of 90° between two adjacent {P2W12} units; (b) dimeric {P4W24} displaying the angle of 36° between two {P2W12} units; it also contains three structurally recognizable {P2W12} units with the angle of 108° between them; (c) trimeric {P6W39} displaying the angle of 60° between two {P2W12} units and 120° between {P2W12} and {WO(H2O)} linker; (d) view of the external and inner diameter of {P6W39}; (e) view of the thickness of {P6W39}; (f) schematic view of the inner cavity shape and size of {P6W39}.

potential tensions among {P2W12} subunits in these trimeric crowns are avoided by three additional {WO(H2O)} linkers. Recently, Kortz et al. reported a novel uranyl-containing “U-shaped” {P2W12}3 aggregate, which could be viewed as a gapped ring obtained by removing a {P2W12} from the {P8W48} unit;16 Cronin and his co-workers obtained a triangular POM aggregate composed of three {Co2M16} Dawson clusters.17 They are structurally different from those of the {P6W39}-based species. Compound 1 shows a 2-D porous framework constructed from novel 3d-4f-cluster-containing {P6W39} aggregates, {Gd(H2O)6}3þ and {Mn(H2O)4}2þ linkers (Figures 1 and 2). In 1, the vacant sites of {P6W39} are filled with two Gd3þ, one Mn2þ, three W6þ ions, and a tartrate ligand (see Figures 1a-d). On one side of the {P6W39} shell, three vacant sites are occupied by two W6þ and one Gd3þ (Gd(3)) ions, which exhibit the six- and nine-coordinated environments, respectively. On the other side, three vacant sites are occupied by a ninecoordinated Gd3þ (Gd(1)), a six-coordinated Mn2þ (Mn(2)), and a six-coordinated W6þ (W(42)), which are linked together by the tartrate ligand through both the hydroxyl and carboxyl groups, resulting in a pair of enantiomeric POM units [(D-TartWMnGd(P6W39)] and [(L-TartWMnGd(P6W39)] (Figures 1a,b). Three Kþ ions are enclosed into the inner cavity of the {P6W39} unit (Figure S1, Supporting Information). To the best of our knowledge, compound 1 represents the first crown-type POM containing both the Ln ions and TM ions. In the polyoxoanion, the chiral tartrate ligand acts as a pentadentate ligand capping on the top of the crowns, which are bridged face to face by the Gd3þ (Gd(2)) ions into a 1-D polymeric chain (Figures 1e,f and S2). This linking mode leads to two chiral segments crystallizing in centrosymmetric space groups. In this 1-D polymeric chain, each Gd3þ ion linked with three neighboring {P6W39} units with Gd-O distances in the range of 2.38(3)-2.54(3) A˚. Another fascinating structural feature for 1 is that the 1-D polymeric chains are bridged together by the {Mn(H2O)4}2þ (Mn(1)) linking units into a 2-D porous framework and the size of the pore is ca. 12.0  14.1 A˚ (Figure 2). These 2-D

Figure 1. Mixed ball-and-stick and the polyhedral representation of compound 1. (a) D-trimeric polyoxoanion; (b) L-trimeric polyoxoanion; (c, d) the coordinated modes of the tartrates in the two enantiomers; (e) ball-and-stick representation of the 1-D chain; and (f) mixed ball-and-stick and the polyhedral representation of the 1-D chain in 1. The (a) and (c) is generated by the symmetry operation -x þ 1, -y þ 1, -z þ 1 of (b) and (d), respectively.

Figure 2. (a) Mixed ball-and-stick and the polyhedral representation of the 2-D porous framework of 1; (b) space-filling representation of the porous 2-D framework of 1.

layers are further connected by Kþ and Naþ cations into a 3-D framework (Figure S3, Supporting Information). Compound 2 exhibits a 1-D chain-like structure constructed from the Co-containing {P6W39} aggregates and {Gd(H2O)7}3þ bridging units (see Figures 3c and S5a). In the Co-containing {P6W39}, the six vacant sites in the {P6W39}

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Figure 3. (a) ORTEP drawing of polyoxoanion in 2 with thermal ellipsoids at 50% probability; (b) mixed ball-and-stick and the polyhedral representation of polyoxoanion in 2; (c) 1-D chain in 2.

shell are occupied by two Co2þ, two W6þ, and two Kþ “guest” ions (Figures 3a,b). As shown in Figure 3b, two “guest” W atoms locate at two different hinges of the trimeric polyoxoanion, while two Co2þ ions are in a same hinge site. Each of them is captured by the crown via two terminal oxo atoms. All the Co2þ and W6þ centers exhibit an octahedral coordination environment. The bond lengths of Co-O are in the range of 1.96(3)-2.18(2) A˚, and, the bond lengths of W-O are in the range of 1.70(2)-2.27(3) A˚. Further, three Kþ cations are encapsulated into the inner cavity of {P6W39} shell (see Figure S2, Supporting Information). It is isostructural to Mn-containing polyoxoanion [K3⊂{Mn(H2O)4}2{WO2(H2O)2}2{P6W39}] in our previous work. However, the Co-containing polyoxoanions are linked to each other by two {Gd(H2O)7}3þ linkers, leading to a 1-D chain along the c-axis, which represents the first example of 1-D structure based on trimeric {P2W12}-based polyoxotungstates. In the 1-D chain, two adjacent crowns are reversely arranged and each of them coordinated with four Gd3þ linkers. Each of the Gd3þ linkers is coordinated with two O atoms derived from two neighboring polyoxoanions and seven coordinated water molecules, resulting in a nine-coordinated environment. The bond lengths of Gd-O are in the range of 2.39(2)2.53(3) A˚. As shown in Figure S5, these 1-D chains are connected by the Kþ, Naþ ions, and extensive H-bonds into a 3-D open framework. Around 77 lattice water molecules reside in the interspaces of the crystal structure. The oxidation states of W, Co, Mn, and Gd sites in 1 and 2 are þ6, þ2, þ2, and þ3, respectively, on the basis of the bond lengths and angles, charge balance consideration, and bond valence sum calculations. Magnetic Properties. The magnetic susceptibilities (χ) of compounds 1 and 2 were measured in the temperature range of 2.0-300 K at a 0.1 T magnetic field (Figure 4). In the χT vs T plots of 1 and 2, the χT products slowly decrease from 300 to 2 K. The χT value of 1 slowly decreases from 36.6 cm3 K mol-1 at 300 K to 31.8 cm3 K mol-1 at 2 K, revealing antiferromagnetic behavior in 1 (Figure 4a). The χ-1 vs T plot is well fitted with the Curie-Weiss law in the whole

Figure 4. Temperature dependence of χ (O) and χT (b) values and (inset) temperature dependence of reciprocal magnetic susceptibility χ-1 for 1 (a), and 2 (b). The red line is the best fit with the CurieWeiss law.

temperature range, resulting in C = 36.7 cm3 K mol-1 and θ = -5.00 K, respectively. The negative Weiss temperature suggests the presence of antiferromagnetic interactions in 1. These antiferromagnetic interactions are mainly attributed to antiferromagnetic coupling between the Gd3þ and Mn2þ ions capsulated in the crown-type polyoxoanion, which has even been observed in 3d-4f-metal coordination polymers.18 For 2, the χT value slowly decreases from 30.73 cm3 K mol-1 at 300 K to 22.22 cm3 K mol-1 at 2 K, revealing antiferromagnetic interaction in 2 (as shown in Figure 4b). The 1/χ vs T curve is well fitted with the Curie-Weiss law, leading to a Curie constant of 31.25 cm3 K mol-1. The Weiss temperature (θ) of -2.18 K indicates a weak antiferromagnetic interaction in 2. Conclusion In conclusion, two new 3d-4f heterometals-containing POMs have been successfully synthesized by the conventional aqueous solution method. Compound 1 represents the first 3d-4f-cluster-containing crown POM, which is further connected into a 2-D porous framework by mixed 3d-4f linkers. The detailed study of the synthetic conditions reveals that the use of the organic ligands (the tartrate and the (CH3)2NH 3 HCl) is an effective method to synthesize the 3d-4f heterometals-containing POMs. The exploration of such crown-type POM system might provide the model for the preparation of new high-nuclear metal clusters (such as other Ln- and Ac- metal clusters-containing aggregates) with desirable electronic, optical, and magnetic properties. The properties and functionalities of such compounds could be tuned by the appropriate choice of different TM

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ions and Ln cations. This continuous research is currently going on in our group.

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Acknowledgment. This work was supported by the National Natural Science Foundation of China (No. 20701005), the Postdoctoral station Foundation of Ministry of Education (No. 20060200002), and the Program for Changjiang Scholars and Innovative Research Team in University. Supporting Information Available: X-ray crystallographic files for compounds 1 and 2 in CIF format, additional structural figures, and physical characterizations. This material is available free of charge via the Internet at http://pubs.acs.org.

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References

(8)

(1) (a) M€ uller, A.; Peters, F.; Pope, M. T.; Gatteschi, D. Chem. Rev. 1998, 98, 239. (b) Rhule, J. T.; Hill, C. L.; Judd, D. A.; Schinazi, R. F. Chem. Rev. 1998, 98, 327. (c) Long, D. L.; Burkholder, E.; Cronin, L. Chem. Soc. Rev. 2007, 36, 105. (d) Juan, J. M. C.; Coronado, E. Coord. Chem. Rev. 1999, 193, 361. (e) Mialane, P.; Dolbecq, A.; Secheresse, F. Chem. Commun. 2006, 3477. (2) (a) Proust, A.; Thouvenot, R.; Gouzerhg, P. Chem. Commun. 2008, 1837. (b) Shishido, S.; Ozeki, T. J. Am. Chem. Soc. 2008, 130, 10588. (c) Zheng, S. T.; Zhang, J.; Yang, G. Y. Angew. Chem., Int. Ed. 2008, 47, 3909. (3) (a) M€ uller, A.; Pope, M. T.; Todea, A. M.; B€ ogge, H.; Slageren, J. van; Dressel, M.; Gouzerh, P.; Thouvenot, R.; Tsukerblat, B.; Bell, A. Angew. Chem., Int. Ed. 2007, 46, 4477. (b) Mal, S. S.; Kortz, U. Angew. Chem., Int. Ed. 2005, 44, 3777. (c) Pichon, C.; Mialane, P.; Dolbecq, A.; Marrot, J.; Riviere, E.; Keita, B.; Nadjo, L.; Secheresse, F. Inorg. Chem. 2007, 46, 5292. (d) Mal, S. S.; Dickman, M. H.; Kortz, U.; Todea, A. M.; Merca, A.; Bc-gge, H.; Glaser, T.; M€uller, A.; Nellutla, S.; Kaur, N.; Tol, J. V.; Dalal, N. S.; Keita, B.; Nadjo, L. Chem.;Eur. J. 2008, 15, 1186. (e) Mitchell, S. G.; Gabb, D.; Ritchie, C.; Hazel, N.; Long, D. L.; Cronin, L. CrystEngComm 2009, 11, 36. (f) Zimmermann, M.; Belai, N.; Butcher, R. J.; Pope, M. T.; Chubarova, E. V.; Dickman, M. H.; Kortz, U. Inorg. Chem. 2007, 46, 1737. (4) (a) Ritchie, C.; Ferguson, A.; Nojiri, H.; Miras, H. N.; Song, ogerler, P.; Y. F.; Long, D. L.; Burkholder, E.; Murrie, M.; K€ Brechin, E. K.; Cronin, L. Angew. Chem., Int. Ed. 2008, 47, 5609. (b) Compain, J. D.; Mialane, P.; Dolbecq, A.; Mbomekalle, I. M.; Marrot, J.; Secheresse, F.; Riviere, E.; Rogez, G.; Wernsdorfer, W. Angew. Chem., Int. Ed. 2009, 48, 3077. (c) Barats, D.; Leitus, G.; Popovitz-Biro, R.; Shimon, L. J. W.; Neumann, R. Angew. Chem., Int. Ed. 2008, 47, 9908. (d) Bi, L. H.; Kortz, U.; Nellutla, S.; Stowe, A. C.; van Tol, J.; Dalal, N. S.; Keita, B.; Nadjo, L. Inorg. Chem. 2005, 44, 896. (5) (a) Lisnard, L.; Mialane, P.; Dolbecq, A.; Marrot, J.; ClementeJuan, J. M.; Coronado, E.; Keita, B.; Oliveira, P. de; Nadjo, L.; Secheresse, F. Chem.;Eur. J. 2007, 13, 3525. (b) Zhao, J. W.; Li, B.; Zheng, S. T.; Yang, G. Y. Cryst. Growth Des. 2007, 7, 2658. (c) Zhang, Z. M.; Li, Y. G.; Wang, E. B.; Wang, X. L.; Qin, C.; An, H. Y. Inorg. Chem. 2006, 45, 4313. (d) Zhang, Z. M.; Wang, E. B.; Qi, Y. F.; Li, Y. G.; Mao, B. D.; Su, Z. M. Cryst. Growth Des. 2007, 7, 1305.

(9)

(10) (11) (12)

(13)

(14)

(15)

(16) (17) (18)

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(e) Zhang, Z. M.; Qi, Y. F.; Qin, C.; Li, Y. G.; Wang, E. B.; Wang, X. L.; Su, Z. M.; Xu, L. Inorg. Chem. 2007, 46, 8162. (a) Kuznetsov, A. E.; Geletii, Y. V.; Hill, C. L.; Morokuma, K.; Musaev, D. G. J. Am. Chem. Soc. 2009, 131, 6844. (b) Copping, R.; Gaunt, A. J.; May, I.; Sharrad, C. A.; Collison, D.; Helliwell, M.; Foxc, O. D.; Jones, C. J. Chem. Commun. 2006, 3788. (c) Kamata, K.; Nakagawa, Y.; Yamaguchi, K.; Mizuno, N. J. Am. Chem. Soc. 2008, 130, 15304. (d) AlDamen, M. A.; Clemente-Juan, J. M.; Coronado, E.; Martí-Gastaldo, C.; Gaita-Ari~no, A. J. Am. Chem. Soc. 2008, 130, 8874. (e) Sartorel, A.; Carraro, M.; Scorrano, G.; Zorzi, R. D. J. Am. Chem. Soc. 2008, 130, 5006. (f) Fukaya, K.; Yamase, T. Angew. Chem., Int. Ed. 2003, 42, 654. (g) Hussain, F.; Gable, R. W.; Speldrich, M.; K€ogerler, P.; Boskovic, C. Chem. Commun. 2009, 328. (h) Li, L.; Shen, Q.; Xue, G.; Xu, H.; Hu, H.; Fu, F.; Wang, J. Dalton Trans. 2008, 5698. (a) Fang, X. K.; K€ ogerler, P. Chem. Commun. 2008, 3396. (b) Fang, X. K.; K€ogerler, P. Angew. Chem., Int. Ed. 2008, 47, 8123. Nohra, B.; Mialane, P.; Dolbecq, A.; Riviere, E.; Marrot, J.; Secheresse, F. Chem. Commun. 2009, 2703. (a) Chen, W. L.; Li, Y. G.; Wang, Y. H.; Wang, E. B. Eur. J. Inorg. Chem. 2007, 2216. (b) Zhang, Z. M.; Li, Y. G.; Chen, W. L.; Wang, E. B.; Wang, X. L. Inorg. Chem. Commun. 2008, 11, 879. (c) Chen, W. L.; Li, Y. G.; Wang, Y. H.; Wang, E. B.; Zhang, Z. M. Dalton Trans. 2008, 865. (a) Wang, J. P.; Yan, Q. X.; Du, X. D.; Niu, J. Y. J. Cluster Sci. 2008, 19, 491. (b) Pang, H.; Zhang, C.; Shi, D.; Chen, Y. Cryst. Growth Des. 2008, 8, 4476. (a) Contant, R.; Teze, A. Inorg. Chem. 1985, 24, 4610. (b) Contant, R. Inorg. Synth. 1990, 27, 104. (a) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refinement; University of G€ottingen: G€ottingen (Germany), 1997; (b) Sheldrick, G. M. SHELXS-97, Program for Crystal Structure ottingen (Germany), 1997. Solution; University of G€ottingen: G€ (a) Godin, B.; Chen, Y. G.; Vaissermann, J.; Ruhlmann, L.; Verdaguer, M.; Gouzerh, P. Angew. Chem., Int. Ed. 2005, 44, 3072. (b) Ostuni, A.; Pope, M. T. C. R. Acad. Sci. Paris S erie IIc, Chimie: Chemistry 2000, 3, 199. (c) Judd, D. A.; Chen, Q.; Campana, C. F.; Hill, C. L. J. Am. Chem. Soc. 1997, 119, 5461. (d) Godin, B.; Vaissermann, J.; Herson, P.; Ruhlmann, L.; Verdaguer, M.; Gouzerh, P. Chem. Commun. 2005, 5624. (a) Contant, R.; Abbessi, M.; Thouvenot, R.; Herve, G. Inorg. Chem. 2004, 43, 3597. (b) Yao, S.; Zhang, Z. M.; Li, Y. G.; Wang, E. B. Dalton Trans. 2009, 1786. (c) Zhang, Z. M.; Yao, S.; Li, Y. G.; Wang, Y. H.; Qi, Y. F.; Wang, E. B. Chem. Commun. 2008, 1650. (d) Zhang, Z. M.; Li, Y. G.; Wang, Y. H.; Qi, Y. F.; Wang, E. B. Inorg. Chem. 2008, 47, 7615. (e) Zhang, Z. M.; Yao, S.; Qi, Y. F.; Li, Y. G.; Wang, Y. H.; Wang, E. B. Dalton Trans. 2008, 3051. (a) Howell, R. C.; Perez, F. G.; Jain, S.; Horrocks, W. D.; Rheingold, A. L., Jr.; Francesconi, L. C. Angew. Chem., Int. Ed. 2001, 40, 4031. (b) Bassil, B. S.; Dickman, M. H.; R€omer, I.; Kammer, B.; Kortz, U. Angew. Chem., Int. Ed. 2007, 46, 6192. (c) Boglio, C.; Micoine, K.; Remy, P.; Hasenknopf, B.; Thorimbert, S.; Lac^ote, E.; Malacria, M.; Afonso, C.; Tabet, J. C. Chem.;Eur. J. 2007, 13, 5426. Mal, S. S.; Dickman, M. H.; Kortz, U. Chem.;Eur. J. 2008, 14, 9851. Mitchell, S. G.; Khanra, S.; Miras, H. N.; Boyd, T.; Long, D. L.; Cronin, L. Chem. Commun. 2009, 2712. Zhao, B.; Cheng, P.; Dai, Y.; Cheng, C.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H.; Wang, G. L. Angew. Chem., Int. Ed. 2003, 42, 934.