Inorg. Chem. 1994,33,409-410
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Synthesis and Structure of Dialuminiohexaeuropiopentakis(hexaniobate): a High-Nuclearity Oxoniobate Complex Tomoji Ozeki,la Toshihiro Yamase,*'la Haruo Naruke,*,lband Yoshinori Sasakilb Research Laboratory of Resources Utilization, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227, Japan, and Department of Applied Chemistry, Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263, Japan Received July 30, 1993 We have reported two photoluminescent polyoxolanthaniometalates with completely new structures, namely K I ~ H ~ [ E U ~ (H20)3(SbW9033)(Ws0i8)31*25.5H202 and (NH4)12H2[EU4(M004)(H2O)16(M07024)4]~13H20.~In these complexes, Eu3+ cations are found to form hydrated clusters, [Eu3(H20)3I9+and [ E u ~ ( M o O ~ ) ( H ~lo+, O )stabilized ~~] by the coordination of polyoxometalateunits to them. In order to expand our investigation on the photoluminescenceand electroluminescenceproperties of 0 polyoxolanthaniotungstatesand polyoxolanthaniomolybdatesto polyoxolanthanioniobates,and also to contribute to the stereochemistry of polyoxoniobates, where only small number of examples have been accumulated compared with those of tungstates and molybdates, synthetic approach to the polyoxolanthanioniobates has been undertaken. Here we report synthesis and crystal structure analysis of dialuminiohexaeuropiopentakis(hexaniobate), { [Eu30(0H)3(0H2)3] 2A12(Nb6019)5)26 (l),which possesses an unprecedented structure with two trimeric oxohydroxoaquoeuropiumclusters coordinated by two A13+cations and five [Nb6019I8-anions. A 0.326-g sample of Eu2O3 was dissolved in 0.5 mL of concentrated HN03and was diluted with 10 mL of water. 0.60 g of [H2edta]Na2*2H20was added to the solution,whose pH was then brought to 10-1 1with concentratedNaOH aqueoussolution. This solution was added dropwiseto 60 mL of an aqueoussolution dissolving 1.2 g of Na7H[Nb6O19]o15H2o4at 353 K with vigorous agitation. A 10 mL aqueous solution of 0.90 g Al(NO3)3*9H20 whosepH was adjusted at 10-1 1was added to the mixture, which Figure 1. ORTEP drawing of anion 1. Two AlO6 octahedra and five was then concentrated to 50 mL by heating. The solution was hexaniobate anions are shown displaced to show the crowded central cooled to 273 K, until a white powder precipitated, which was [Eu30(0H)3(OH2)3l4+cores. Shaded circles represent 0 atoms of the removed by filtering it off. The filtrate, which was still turbid, equatorial hexaniobate anions which coordinate to the central Eu atoms. was brought to clearnessby heating with an additional minimum comprised of two [Eu30(0H)3(OH2)3I4+ clusters, two A13+ amount of water. The solutionwas filtered again and the filtrate cations, and five hexaniobate anions, [Nb60pl8-. The anion 1 was kept at room temperature, from which the colorless crystals has an approximate0 3 point symmetry. Three hexaniobateanions were obtained after severalweeks. This compound is not specific are on the 2-fold axes, which will be referred to as equatorial to Eu3+ but presumably can form for various kinds of trivalent [Nb6019I8-anions. The other two hexaniobate anions are on the lanthanide elements. An attempt to prepare a Tb3+derivative 3-fold axis, which will be called as axial [Nba019]8- anions by a similar procedure gave colorless single crystals containing hereafter. Each AP+ cation is on the molecular 3-fold axis in a the isostructural [Tb,jA12(Nb6)5] framework.5 trigonally distorted octahedral coordination field, with one basal X-ray crystal structure analysis6of the sodiumsalt of 1showed triangle being shared with a central [Eu30(OH)3(OH2)3I4+cluster that 1 has the structure illustrated in Figure 1. The anion is and the other with an axial [ N b & # - anion. The coordination of the axial [Nb601#- anions to the A1 atoms is achieved by the (a) Tokyo Institute of Technology. (b) Chiba University. Yamase, T.; Naruke, H.; Sasaki, Y .J. Chem. Soc., Dalton Trans. 1990, three adjacent p2-(Nb2) oxygen atoms and is similar to that 1687-1696. observed in the [Mn(Nb6O19)2]12- anion.7 The coordination of Naruke, H.; Ozeki, T.; Yamase, T. Acta Crystallogr. 1991,C47,489the equatorial [Nb6Ol#-anion to the Eu3+atoms is also achieved 492. Flynn, C. M., Jr.; Stucky, G. D. Znorg. Chem. 1969,8, 332-334. by the three adjacent pZ-(Nb2) oxygen atoms, which indicates A similar procedure, using 0.345 g of Tb4O.r instead of Eu2O3 as the the high coordinating ability of this triad of 0 atoms, presumably starting material gives colorless crystals of the Tb derivativeof 1,whose X-ray crystal structure analysis is in progress, and the same Tb&(Nb& framework has already been confirmed-with the crystallogra hic data being as follows: triclinic space group P1 with a = 20.60(1) b = 18.05(1) A, c = 27.52 2) A, a = 110.63(5)', B = 91.22(6)', y = 117.05(4)', V = 8325(13)63,andZ= 2. Diffractiondatawerecollected on a Rigaku AFC5R diffractometer at 298 K, using graphitemonochromatized Mo Ka radiation, to a maximum 28 = 50°, giving 30 027 reflections. The Tb positions were determinedby direct methods using the program MITHRIL (Gilmore, G. J. J. Appl. Crystallogr. 1984,17,4246) andNbpositionswereobtainedbytheprogramDIRDIF (Parthasarathi, V.; Beurskens, P. T.; Slot, H. J. B. Acta Crystallogr. 1983, A39, 860-864). The current discrepancy indices are R = 0.199 and R, = 0.188 for 340 parameters and 5671 independent reflections with Z > 3 4 ) .
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0020-1669/94/ 1333-0409$04.50/0
(6) Crystallographic data for Na7H19([Eu3O(OH)3(OH2)3]2Al2(Nb&)&47H20: Empirical formu13based on diffraction data is AlzENHl 1Na7Nb3&6, s ace group P1 with a = 23.15(2) A, b = 28.31(2) c = 19.32(2) a = 107.03(6)', /3 = 113.44(10)', 7 = 100.81(8)', V = 10418(25) A3, and 2 = 2. Diffraction data were collected on a Rigaku AFC5R diffractometer at 298 K, using graphitemonochromatized MoKa radiation, to a maximum 28 = 50°, giving 37 474 reflections. The structure was solved by direct methods using the program SHELXS86 (Sheldrick, G. M. Acta Crystallogr. 1990, A46,467473). The final discrepancy indices were R = 0.087 and R, = 0.086 for 1006 parameters and 12 275 independent reflections with z > 3a(z). (7) Flynn, C. M., Jr.; Stucky, G. D. Znorg. Chem. 1969,8, 335-344.
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410 Inorganic Chemistry, Vol. 33, No. 3, 1994
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Figure 2. Stereoscopicdrawing of the central { [ E u ~ O ( O H ) ~ ( O H ~ ) ~ ] ~ ) ~ + cluster viewed along its 3-fold axis. 0 1 and 0 2 are 02-triply shared by three Eu3+, 0 3 - 0 8 are OH- shared by two E 3 + and one AP+, and 09-014 are OH2 groups. Other 0 atoms shown in shaded circles are those of the three equatorial [Nb6019I8-anions. Eu--Eu distances (A) are as follows: Eul--Eu2 = 3.762(4), Eu2-Eu3 = 3.777(5), Eu3-Eul = 3.771(7), Eu4***Eu5= 3.741(7), Eu5***Eu6= 3.740(7), Eu6*-Eu4 = 3.743(5), Eul--Eu4 = 4.650(5), E u ~ * - E u=~ 4.646(7), Eu3***Eu6= 4.609(6), Eul--Eu6 = 4.753(7), Eu2-Eu4 = 4.763(6), and Eu3-Eu5 = 4.717(5).
due to the high negative charge of the [Nb6019I8- anion. An isostructural oxovanadateanion, [v6019]8-,behaves as a tridentate ligand chelating to four organometallic groups,8 and [mW4019]& also serves as a tridentate ligand to some organometallicgroups.!) In contrast,an isostructuraloxotungstateanion, [w6019]2-, which possesses a smaller negative charge, barely chelates to cationic fragments with a similar mode of coordination but serves as a tetradentate ligand by forming a lacunary [w5O18l6- moiety as found in [L~W~OOW]" lo and [Eu3(H20)3(SbW9033)(W5018)3]18-? Figure 2 shows the stereoscopic drawing of the central [Eu30(OH)3(OH2)3I4+clusterswith the atom numberingscheme. Each Eu atom achieves 8-fold coordination, with one terminal 0 atom, one 0 atom shared by three Eu atoms, two 0 atoms shared by two Eu atoms and one A1 atom, and four atoms of the equatorial [Nb6O19l8-anions, three of which are the p~(Nb2)-0atoms of one [Nb6019I8-anion while the other is the terminal 0 atom of another [Nb6019I8- anion. Eul, Eu2, and Eu3 form a doubly bridged trimeric [Eu30(OH)3(OH2)3I4+core with a triply shared 0 atom, 01, and three doubly shared atoms, 0 3 , 0 4 , and 0 5 . 03,04, and 0 5 are also linked to All. Likewise, Eu4, Eu5, and Eu6 form an [Eu3O(OH)3(OH2)3I4+cluster with 02(p3), 06, 07, and 0 8 atoms. 06,07, and 0 8 are coordinated to A12. The bond valence sums1 at 0 1 and 0 2 are 1.51 and 1.72, suggesting that these are 02-, while the six 0 atoms 03-08 can be regarded as the 0 atomsof hydroxy groupsjudging from their bond valence sum, ranging from 1.1 1 to 1.23. The terminal 0 atoms, 09014, show bond valence sums from 0.29 to 0.40 and are likely to be the 0 atoms of water molecules. Six oxygen atoms, 0308, are coordinated to the A1 atoms to form the basal triangles of the trigonally distortedA106 octahedra. The Eu ...Eu distances (8) (a) Hayashi, Y.; Ozawa, Y.; Isobe, K.Chem. Lett. 1989,425-428. (b) Che, H. K.; Klemperer, W. G.; Day, V. W. Inorg. Chem. 1989, 28, 1423-1 424. (9) (a) [(OC)3M(Nb2W4019)]s (M = Mn, Re): Besecker, C. J.; Day, V. W.; Klemperer, W. G.; Thompson, M. R. Inorg. Chem. 1985,24,44-50. (b) ([(CH3)5CsRh][Nb~W4019])~-:Besecker, C. J.; Day, V. W.; Klemperer, W. G.; Thompson, M. R. J. Am. Chem. SOC.1984,106, 4125-4136. (10) (a) Ln = CeIV: Iball, J.; Low, J. N.; Weakley, T. J. R. J. Chem.Soc., Dalton Trans. 1974,2021-2024. (b) Ln = T b F Ozeki, T.; Takahashi, M.; Yamase, T. Acta Crystallogr. 1992, C48, 1370-1374. (c) Ln = E u F Sugeta, M.; Yamase, T. Bull. Chem. Soc. Jpn. 1993,66,444449. (d) Ln = Smlk Ozeki, T.;Yamase, T. Acta Crystallogr. 1993, C49, 1574-1577. (e) Ln = G d F Yamase, T.; Ozeki, T. Acta Crystallogr. 1993, C49, 1577-1 580. (1 1) Bond valence sum, VI, was calculated according to the equation fi = 2j exp((r0 - ru)/B), where B = 0.37 A and ro = 2.074 A for Eu-0 bonds, 1.651 A for A 1 4 bonds, and 1.911 A for Nb-0 bonds (Brown, I. D.; Altermatt, D. Acta Crystallogr. 1985, B41, 244-247).
Figure 3. Drawing of anion 1 with the [NbaO19]' groups shown in the polyhedral representations. One of the three equatorial [Nb601g]8-anion is not shown to show the central { [ E U ~ O ( O H ) ~ ( O H ~core. ) ~ ] ~ Shaded )~+ circles represent the 0 atoms of the hidden [Nb6019]8- anion which coordinate to the Eu atoms.
in these [Eu30(OH)3(OH2)3I4+clusters are 3.76(1) A; this is shorter by about 1.3 A than that in the singly bridged trimeric [Eu3(H20)3]9+ core in K15H3 [Eu3(H20)3(SbW9033)(Ws018)3]-25.5H*o,where they were 5.067(4) and 5.015(5) A.2The two [ E u ~ O ( O H ) ~ ( O H ~clusters ) ~ ] ~ +are linked to each other via the three equatorial [Nb6O19l8-anions. The E w E u distances among the two Eu atoms in different [ E u ~ O ( O H ) ~ ( O H ~ ) ~ ] ~ + clusters are 4.75(2) A for the two Eu atoms sharing a common 0 atom and 4.64(2) A elsewhere. Figure 3 shows an alternative representation of the anion 1 with one [Nb6O19l8-group unshown for clarity and the other four shown with polyhedral representations. An [Nb6019I8- anion has three kinds of 0 atoms: six terminal 0 atoms, 12 bridging p2-(Nbz)-O atoms and one central pg-(Nb6)-0 atom. A free [Nb6019I8-anion has an oh point symmetry. The coordination of the [Nb&9]*- anions to the central [Eu30(0H)3(0H2)3I4+ clusters or the AP+ cations reduce the Oh symmetry to CZ,and C3ufor equatorial and axial [Nb6019I8-anions, respectively. The Nb-O distances in the [Nb6019I8-anions in 1 tend to correlate with the number of Eu3+or A13+atoms linked to the concerning 0 atoms. In each equatorial [Nb6019I8-anion, two terminal 0 atoms are bonded to two Eu3+atmos, resulting in the elongation of the Nb-O distances to 1.82(2) A compared with the other terminal Nb-O bonds of 1.75(4) A. One of the 12 bridging pz-(Nb+O atom coordinates to two Eu3+ atoms resulting in Nb-0 distances of 2.09(3) A, while the four p2-(Nb2)-0 atoms linked to one Eu3+atom exhibit Nb-O distances of 2.01(4) A, and the Nb-O distances for the other p2-(Nb2)-0 atoms are 1.95(5) A. Thusthesymmetryoftheequatorial[Nb6019]8-anions are reduced to CZ,.In each axial [Nb6019I8-anion in 1, three p2(Nb2)-0 atomsare bonded to the A1atoms, with N W distances of 2.10(4) A and Al-0 distances of 1.89(3) A. The Nb-O distances for the other p2-(Nb2)-0 atoms are 1.95(5) A. The terminal Nb-O bonds are 1.76(6) A. Therefore, the symmetry of the axial [Nb6019I8-anions is reduced to c3v. SupplementaryMaterial Available: Tables of experimentaldetails and crystal parameters, tables of atomic positional parameters, anisotropic thermal parameters, bond lengthsand angles,and atomiccontacts, packing diagram of the unit cell, and a drawingof anion 1with completenumbering of atoms (38 pages). Ordering information is given on any current masthead page.
