J O U R N A L O F C H E M I S T R Y Materials Hybrid open frameworks (MIL-n). Part 5† Synthesis and crystal structure of MIL-9: a new three-dimensional ferrimagnetic cobalt(II ) carboxylate with a two-dimensional array of edge-sharing Co octahedra with 12-membered rings Carine Livage,a Chrystelle Egger,a Marc Noguesb and Ge�rard Fe� rey*a aInstitut Lavoisier, Universite� de Versailles St-Quentin, 45 av.des Etats-Unis, 78035 Versailles, France. E-mail: ferey@chimie.uvsq.fr; livage@chimie.uvsq.fr bLaboratoire de Magne�tisme et d’Optique, Universite� de Versailles St-Quentin, 45 av. des Etats- Unis, 78035 Versailles, France Received 9th April 1998, Accepted 17th September 1998 Co5(OH)2(C4H4O4)4, a new cobalt(II ) succinate with an open framework, was prepared hydrothermally (180 °C, 72 h, autogenous pressure) from a 253585120 mixture of Co(II) chloride, succinic acid, potassium hydroxide and water.Its monoclinic structure was solved by single crystal X-ray diVraction [space group P21/c (no. 14) with a=9.5631(2) A° , b=9.4538(2) A° , c=12.5554(2) A° , b=96.968(1)°, V=1126.72(4) A° 3, Z=4] from 3077 unique reflections [I2s(I )], R1=0.020 and wR2=0.054. The three-dimensional structure is built up from layers of edge sharing octahedra pillared by succinate ions.Within the layers, cobalt octahedra form 12-membered ring windows. Below 10 K, Co5(OH)2(C4H4O4)4, exhibits ferrimagnetic behavior. to the molar composition of 2 CoCl2·6H2053 CO2 H- Introduction (CH2)2CO2H58 KOH5120 H2O, was homogenized for 10 min The preparation of three-dimensional open frameworks based in an ultrasonic bath and the resulting solution was heated on transition metals is one of the most important aims of for three days at 180 °C under autogenous pressure (pH research due to their practical application as catalysts, hosts around 6).The resulting solid phase was collected by filin intercalation compounds and their potential electronic tration, washed with distilled water and dried at room temperaproperties. 1–3 Among the 3d metal zeolite analogues, some of ture. The solid product was a single phase with large hexagonal the most promising and studied materials are those based on dark red crystals of the title compound and was obtained in cobalt.4–7 With the utilization of the hydrothermal technique, a yield based on cobalt of around 70%.The X-ray powder considerable progress has been reported on the development diVraction pattern is in agreement with that calculated after of open framework compounds based on cobalt, and the resolution of the structure. A single crystal of suitable size was literature already contains numerous examples of cobalt phos- used for structure determination by X-ray diVraction.IR phates and phosphonates with a large structural variety.8–14 spectra exhibited the following relevant features (KBr pellet): We recently introduced a new way for obtaining microporous a narrow band due to the hydroxyl group, n(CoO–H) materials in which both organic (dicarboxylates) and inorganic 3330 cm-1; n(C–H) stretching bands characteristic of CH2 species build the open framework.3,15,16 We present here the groups between 2910 and 3000 cm-1; a very broad band, synthesis and characterization of Co5(OH)2(C4H4O4)4, a new composed of four peaks between 1510 and 1610 cm-1, associcobalt carboxylate with a two dimensional array of edge- ated with the deprotonated carboxylic groups, and the followsharing Co2+ octahedra pillared by succinate ions.ing relevant bands; 1460, 1440, 1420, 1410, 1325, 1305, 1275, Co5(OH)2(C4H4O4)4 is denoted MIL-9 for Materials of 1240, 1225, 1180, 1165, 1035, 865, 810, 680, 660, 565, 510 and Institut Lavoisier. 380 cm-1. TG measurements under oxygen gas flow showed a unique and abrupt weight loss around 320 °C characteristic Experimental of the combustion of the organic moiety (theoretical weight loss 53%, observed 56%).The resulting product at 350 °C is Materials and methods CoO. Satisfactory elemental analysis was obtained. Hydrothermal reactions were carried out in 23 ml Teflonwalled Parr acid digestion bombs. X-Ray powder diVraction Single crystal structure determination data were collected on a Siemens D5000 diVractometer (Cu- Ka radiation). FTIR spectra were obtained on a Nicolet One of the dark red hexagonal crystals of Co5(OH)2(C4H4O4)4 Magna-IR 550 spectrometer.TG measurements were done (0.5×0.3×0.15 mm) was glued to a glass fiber and mounted using a TA-instrument 2050 thermo-analyser (oxygen gas flow, on a Siemens SMART CCD diVractometer using monochro- 5 °Cmin-1). Susceptibility measurements were carried out matic molybdenum radiation [l(MoKa)=0.7107 A° ].Intensity using a SQUID magnetometer; data were not corrected for data were collected on a one half sphere in 1271 frames with diamagnetism. v scans (width of 0.30° and exposure time 30 s per frame). A summary of crystal data is presented in Table 1. The data Hydrothermal synthesis and characterization of collected (7953 total reflections, 3077 unique) were corrected Co5(OH)2(C4H4O4)4 for Lorentz and polarization eVects. Absorption corrections were applied using the SADABS program.17 The structure A hydrothermal synthesis has been set up using CoCl2·6H2O as the cobalt source.The starting mixture, corresponding was solved by direct methods and standard diVerence Fourier techniques (SHELXL-93).18 Cobalt and oxygen atoms were first located and all the remaining atoms, including hydrogen †Part 4: preceding paper.J. Mater. Chem., 1998, 8, 2743–2747 2743Table 1 Summary of crystal data and structure refinement tivity of the three Co2+ ions is given in Fig. 2. Co(1)O6 and Co(2)O6 octahedra are strongly distorted, with three short Formula weight 396.5 Co–O bond distances (2.02–2.09 A° ), two medium Space group P21/c (2.17–2.22 A° ) and one long [2.368(1) and 2.314(1) A° ].By Unit cell dimensions contrast, Co(3), which lies on an inversion center, has a a/A° 9.5631(2) b/A° 9.4538(2) regular octahedral geometry with Co–O bonds of ca. c/A° 12.5554(2) 2.11±0.05 A° . The hydroxide oxygen atom, O(9), is shared b/degrees 96.9680(10) between the three distinct cobalt atoms with Co–m3-O(H) Volume/A° 3, Z 1126.72(4), 2 bonds between 2.02 and 2.11 A° .Only one noticeable hydrogen Dc/Mg m3 2.337 bond linkage exists in the solid, a bond between the hydrogen Absorption coeYcient/mm-1 3.697 atom of the hydroxide group and an oxygen atom of a F(000) 786 Crystal size/mm 0.5×0.3×0.15 neighboring octahedron [(O(9)–H(9),O(3) 2.073 A° ]. The h range for data collection/degrees 2.70–30.24 metallic oxide framework can be described as an infinite square Limiting indices -12h12, -12k13, net of edge-sharing cobalt octahedra.Co(3) octahedra occupy -17l11 the vertices of this square net. The topology creates lozenge- Goodness-of-fit on F2 1.044 shaped cavities made from 12 edge-sharing octahedra in which Final R indices [I>2s(I )] R1=0.0202, wR2=0.0540 one of the two alkyl chain [carbons C(1)–C(4)] is located R indices (all data) R1=0.0236, wR2=0.0551 Largest diV.peak and hole/e A° -3 0.535 and -0.395 (Fig. 3). Each dicarboxylate anions has covalent bonds with the three diVerent cobalt atoms: with one carboxylic group bridging two pairs of cobalt octahedra (Co–m2-O, bond lengths atoms, were found by diVerence Fourier maps.Refinements between 2.06 and 2.31 A° ) and the other linking two cobalt (206 parameters) were performed by full-matrix least-squares octahedra (Co–m1-O, bond lengths between 2.02 and 2.09 A° ). analysis, with anisotropic thermal parameters for all non- The first succinate is in the layers [carbons C(1)–C(4)] while hydrogen atoms. The reliability factors converged to R1(FO)= the second one [carbons C(5)–C(8)], in which the same type 0.020 and wR2(FO2)=0.054.Fractional atomic coordinates of linkage occurs, acts as a pillar leading to a three-dimensional are given in Table 2 and selected bonds distances and angles structure (Fig structure can be estimated as a class in Table 3. IV solid for cobalt compounds in the classification of Stucky.10 Full crystallographic details, excluding structure factors, have been deposited at the Cambridge Crystallographic Data Magnetic properties Centre (CCDC).See Information for Authors, J. Mater. The presence of the infinite array of edge sharing Co2+ Chem., 1998, Issue 1. Any request to the CCDC for this octahedra has, of course, an important eVect on the magnetic material should quote the full literature citation and the properties of the compound, with the predicable existence of reference number 1145/121.strong magnetic couplings between the d7 centers. The temperature dependence of x-1, measured with a SQUID suscep- Results tometer (100 G), is shown in Fig. 5 with the magnetization vs. the applied magnetic field at 2 K. The linear fit of x-1(T) data Structure of Co5(OH)2(C4H4O4)4 above 50 K indicates a Curie–Weiss law (C=18.73 emu mol-1 The three-dimensional framework consists of an infinite and hP=-72.5 K) as well as the room temperature eVective two-dimensional array of edge-sharing cobalt octahedra (b, c moment of 5.5 mB per atom which is slightly larger than the plane) covalently linked by two diVerent succinate anions commonly observed magnetic moments for independent (Fig. 1). The layers are stacked along the a axis, the length of Co2+octahedra.19 Around 25 K a marked change in the x-1(T) which is the interlayer spacing (9.56 A° ). Cobalt atoms occupy curve, characterized by an important increase of susceptibility, three diVerent crystallographic sites with an octahedral coordi- indicates a ferrimagnetic behavior confirmed by the M(H) nation of oxygen atoms arising from the two succinate ions curve below the critical temperature (TC#10 K).The ferrimagand one hydroxyl group. A representation of the local connec- netism of the title compound can be easily understood from structural considerations and superexchange analysis.20 Indeed, another way of describing the layers starts from the Table 2 Atomic coordinates (×104) and equivalent isotropic fact that the diVerent cobalt sites of the structure have diVerent displacement parameters (10-3 A° 2) for non-hydrogen atoms Atom x y z Ueq a Co(1) 8853(1) 2072(1) 1645(1) 14(1) Co(2) 11659(1) 3195(1) 3457(1) 14(1) Co(3) 10000 0 0 12(1) O(1) 8741(1) 1902(1) -127(1) 17(1) O(2) 9520(1) 2268(1) 3356(1) 18(1) O(3) 8519(1) 4230(1) 1632(1) 22(1) O(4) 12546(1) 1280(1) 3921(1) 29(1) O(5) 11299(1) 2546(1) 1767(1) 17(1) O(6) 11696(1) 3642(1) 5272(1) 18(1) O(7) 13551(1) 4184(1) 3464(1) 23(1) O(8) 6708(1) 1577(1) 1592(1) 22(1) O(9) 9497(1) 41(1) 1591(1) 13(1) C(1) 8734(2) 2819(2) -877(1) 16(1) C(2) 7740(3) 4072(3) -913(2) 45(1) C(3) 6832(2) 4237(2) 12(1) 21(1) C(4) 12342(2) -33(2) 4015(1) 17(1) C(5) 12138(2) 2996(2) 6153(1) 15(1) C(6) 13747(2) 2938(2) 6425(2) 22(1) Fig. 1 Representation of the structure parallel to the crystallographic C(7) 15642(2) 5552(2) 3533(2) 26(1) C(8) 14024(2) 5442(2) 3467(1) 17(1) a axis. Black spheres are carbon atoms C(1)KC(4) which connect the octahedra in the cobalt layer. Gray spheres [C(5)KC(8)] correspond aUeq is defined as one third of the trace of the orthogonalized Uij tensor.to the second succinate ion linking two successive layers. 2744 J. Mater. Chem., 1998, 8, 2743–2747Table 3 Selected bond lengths (A° ) and angles (degrees) for Co5(OH)2(C4H4O4)4 a Co(1)KO(9) 2.0199(10) Co(3)KO(1) 2.1587(10 Co(1)KO(3) 2.0649(12) Co(3)KO(1)d 2.1587(10) Co(1)KO(8) 2.0973(12) O(1)KC(1) 1.279(2) Co(1)KO(2) 2.1730(11) O(2)KC(1)e 1.294(2) Co(1)KO(1) 2.2211(11) O(3)KC(4)a 1.289(2) Co(1)KO(5) 2.3682(11) O(4)KC(4) 1.264(2) Co(2)KO(7) 2.0357(11) O(5)KC(5)b 1.284(2) Co(2)KO(4) 2.0536(12) O(6)KC(5) 1.289(2) Co(2)KO(9)a 2.0634(10) O(7)KC(8) 1.272(2) Co(2)KO(5) 2.1960(11) O(8)KC(8)c 1.278(2) Co(2)KO(2) 2.2149(11) C(1)KC(2) 1.516(2) Co(2)KO(6) 2.3138(11) C(2)KC(3) 1.540(3) Co(3)KO(6)b 2.0644(11) C(3)KC(4)a 1.535(2) Co(3)KO(6)e 2.0644(11) C(5)KC(6) 1.536(2) Co(3)KO(9) 2.1111(11) C(6)KC(7)f 1.541(2) Co(3)KO(9)d 2.1112(11) C(7)KC(8) 1.543(2) O(9)KCo(1)KO(3) 170.53(5) O(9)aKCo(2)KO(2) 81.08(4) O(9)KCo(1)KO(8) 95.07(4) O(5)KCo(2)KO(2) 78.37(4) O(3)KCo(1)KO(8) 94.02(5) O(7)KCo(2)KO(6) 90.25(5) O(9)KCo(1)KO(2) 93.45(4) O(4)KCo(2)KO(6) 85.70(5) O(3)KCo(1)KO(2) 87.16(4) O(9)aKCo(2)KO(6) 79.55(4) O(8)KCo(1)KO(2) 102.67(5) O(5)KCo(2)KO(6) 169.99(4) O(9)KCo(1)KO(1) 82.84(4) O(2)KCo(2)KO(6) 91.85(4) O(3)KCo(1)KO(1) 94.28(4) O(6)bKCo(3)KO(6)c 180.0 O(8)KCo(1)KO(1) 91.37(5) O(6)bKCo(3)KO(9) 95.53(4) O(2)KCo(1)KO(1) 165.77(4) O(6)cKCo(3)KO(9) 84.47(4) O(9)KCo(1)KO(5) 83.05(4) O(6)bKCo(3)KO(9)d 84.47(4) O(3)KCo(1)KO(5) 87.96(4) O(6)cKCo(3)KO(9)d 95.53(4) O(8)KCo(1)KO(5) 177.31(4) O(9)KCo(3)KO(9)d 180.0 O(2)KCo(1)KO(5) 75.58(4) O(6)bKCo(3)KO(1) 85.07(4) O(1)KCo(1)KO(5) 90.31(4) O(6)cKCo(3)KO(1) 94.93(4) O(7)KCo(2)KO(4) 93.89(5) O(9)KCo(3)KO(1) 82.29(4) O(7)KCo(2)KO(9)a 94.83(4) O(9)dKCo(3)KO(1) 97.71(4) O(4)KCo(2)KO(9)a 162.87(5) O(6)bKCo(3)KO(1)d 94.93(4) O(7)KCo(2)KO(5) 99.67(5) O(6)cKCo(3)KO(1)d 85.07(4) O(4)KCo(2)KO(5) 92.23(5) O(9)KCo(3)KO(1)d 97.71(4) O(9)aKCo(2)KO(5) 100.79(4) O(9)dKCo(3)KO(1)d 82.29(4) O(7)KCo(2)KO(2) 174.98(5) O(1)KCo(3)KO(1)d 180.0 O(4)KCo(2)KO(2) 90.81(5) Magnetic couplings Within the pentamer Between pentamers Co(1)KO(1)KCo(3) 91.5 Co(1)KO(5)KCo(2) 98.8 Co(1)KO(9)KCo(3) 98.9 Co(1)KO(2)KCo(2) 104.4 Co(1)KO(9)KCo(2) 129.8 Co(2)KO(9)KCo(3) 97.9 Co(2)KO(6)KCo(3) 91.9 Symmetry transformations used to generate equivalent atoms: a-x+2, y+1/2, -z+1/2; b-x+2, y-1/2, -z+1/2; cx, -y+1/2, z-1/2; d-x+2, -y, -z; ex, -y+1/2, z+1/2; f-x+3, -y+1, -z+1.Fig. 2 Local connectivity for the three Co2+. {CoO6 } octahedra are represented by a polyhedral representation and organic alkyl chains Fig. 3 Polyhedral representation of the twelve-membered rings cavity by a ball and stick representation [black spheres C(1)KC(4) and gray spheres C(5)KC(8)].The small black sphere corresponds to the defined by the 2-D array of CoKOKCo. The organic moieties, covalently bond to cobalt atoms, have been omitted for clarity. hydroxyl group O(9)KH. J. Mater. Chem., 1998, 8, 2743–2747 2745Fig. 4 Representation of one layer of the structure of Co5(OH)2- (C4H4O4)4. {CoO6} octahedra are represented by a polyhedral repre- Fig. 6 Representation showing the connectivity between cobalt sentation and organic alkyl chains by a ball-and-stick representaoctahedra within the pentamers. The organic chains have been omitted tion. for clarity. Therefore, the observed ferrimagnetic behavior can be justified assuming (i) antiferromagnetic couplings within the pentamer, which leads, owing to the diVerent multiplicities of the Co sites, to a resulting moment of 3mCo2+; (ii) a ferromagnetic coupling between the pentamers to avoid the compensation of the moments, which implies a Co(1)RO(2)S SO(5)R Co(2) ferromagnetic interaction in agreement with the largest superexchange angles of the structure, and (iii) a ferromagnetic coupling between the layers.Such a proposal is currently being studied by neutron diVraction.Conclusion Owing to the diYculties in synthesizing pure metal oxides with an open framework, synthetic strategies using organic agents are of interest for the self-assembly of infinite solids.3,6 Dicarboxylic acids have long been known to act as chelating ligands, generating isolated metal complexes. With the synthesis of Co5(OH)2(C4H4O4)4 we have demonstrated that, using a hydrothermal technique, dicarboxylic acids can participate in the skeleton with inorganic species and lead to non templated open framework solids, in which they act both as part of the oxide sheet and as pillars between the latter.This type of building leads also to magnetic solids. Study of the Fig. 5 Temperature dependence of x-1 (a) and M(H) at 2K (b). magnetic structure of the title compound is currently in progress.Complementary studies are on the way for tailoring the structure by changing the length of the dicarboxylate multiplicities, the WyckoV positions being 4e, 4e and 2a for Co(1), Co(2) and Co(3) respectively. Therefore, Co(3) is chains. surrounded by two Co(1) and two Co(2), and generates a pentameric unit in which Co(1) and Co(2) octahedra are References linked by corners [O(9) atoms] and share edges with Co(3) (Fig. 6). The layer is generated by the connection of these 1 R. C. Haushalter and L. 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