J O U R N A L O F C H E M I S T R Y Materials A new three-dimensional sodium molybdenum(v) hydroxymonophosphate: Na8(Mo2O4OH)3(PO4)3(PO3OH)·12.25H2O A. Leclaire,*a C. Biot,a H. Rebbah,*b M. M. Borela and B. Raveaua aL aboratoire CRISMAT , URA 1318 associe�e au CNRS, ISMRA et Universite� de Caen—Bd du Mare�chal Juin 14050- Caen cedex- France bL aboratoire de cristallographie et cristallogene`se-Institut de Chimie U.S.T .H.B.B.P. 32 El-Alia Bab-Ezzouar Alger—Alge�rie A new sodium molybdenum(V) hydroxymonophosphate, Na8(Mo2O4OH)3(PO4)3(PO3OH)·12.25 H2O has been synthesized. It crystallizes in the monoclinic space group P21/c with a=13.024(4), b=25.936(4), c=13.276(3) A ° , b=111.72(2)°. Its structure involves Na[Mo6P4O27(OH)4]2 clusters similar to those encountered in several other molybdenum(V) hydroxyphosphates.Such clusters built up of two rings of six edge-sharing Mo octahedra interconnected through one NaO6 octahedron diVer from those previously described by the fact that hydrogen is mainly connected to the MoMO bond forming twelve Mo(O5OH) octahedra, whereas among the eight tetrahedra one observes two P(O3OH) tetrahedra and six PO4 tetrahedra.The originality of this structure deals with the fact that such clusters form with several sodium octahedra, Na(H2O)4O2 and Na(H2O)2O4, a threedimensional framework that delimits intersecting tunnels running along a, b and c. The coordination of other sodium cations and H2O molecules that can be considered as intercalated species is also discussed. The studies of reduced molybdenum phosphates and hydroxy- (Prolabo, 98%) Na2MoO4·2H2O (Merck, 99.5%) and finely phosphates performed in the last ten years, have shown that divided metallic molybdenum (Goodfellow, 99.9%).The best these compounds exhibit a large structural diversity. Numerous results for such a synthesis were obtained from a mixture of layer and tunnel structures have been generated which are of 1.442 g of Na2MoO4·2H2O, 0.634 g of NaOH, 0.230 g of Mo, relevance to applications in catalysis owing to their micropo- 1 cm3 of H3PO4 and 7 cm3 H2O highly homogenized in a rous character and also their redox properties (for reviews 25 cm3 Teflon lined autoclave.The reaction vessel was mainsee ref. 1–4). tained at 220 °C and autogenous pressure for 36 h before slow The structural chemistry of the anhydrous molybdenum cooling at 1.6° h-1 to room temperature.phosphates is generally diVerent from that of the hydroxyphos- By this method, well formed orange crystals could be easily phates. In the anhydrous phosphates, a large number of infinite separated from a roseate powder, whose crystallographic three-dimensional frameworks built up from MoO6 octahedra nature was not identified.The orange crystals were washed and PO4 tetrahedra only can be generated. This is not the with water, rinsed with ethanol and finally dried in a desiccator. case for hydroxyphosphates, where most of the time molyb- Microprobe analysis of these crystals evidenced a cationic denum and phosphorus form isolated polyanionic groups with ratio Na5Mo5P of 85654 in accord with the formula oxygen and hydroxy groups, that are held together in a three- Na8(Mo2O4OH)3(PO4)3(PO3OH)·12.25 H2O deduced later dimensional framework by introducing foreign cations such as from the crystal structure determination.transition or post transition cations (e.g. iron, zinc) or univalent Thermogravimetry, performed under argon between 25 and cations (e.g.alkali). Thus, the molybdenum hydroxyphosphates 600 °C, shows a continuous loss of water in good agreement are less stable, involve stabilization by hydrogen bonding only with the presence of 28.5 hydrogen atoms per formula and are generally prepared by hydrothermal techniques. For unit (Dmobs=17%; Dmcalc=18%). No intermediate phase this reason, the number of molybdenum(V) hydroxyphosphates could be detected during the dehydration owing to the poor of alkali cations that do not involve any other transition or crystallization of the products.post transition elements is small compared to anhydrous molybdenum(V) phosphates. The sodium hydroxyphosphates (PPh4)2[(H3O)2NaMo6P4O24(OH)7]·5H2O,5 Na3[Mo2O4- Structure determination (HPO4) (PO4)]·2H2O,6 and (Et4N)6Na2[Na12(H3PO4)- An orange plate like crystal with dimensions 0.097×0.168 x {Mo6O15(HPO4) (H2PO4)3}4]·xH2O7 and the caesium 0.036 mm was selected for the structure determination.The hydroxyphosphate Cs(H3O)[Mo2O2(PO4)2(HPO4)]8 are repcell parameters reported in Table 1 were determined and resentative of the unusual molybdenum(V) alkali hydroxyrefined by diVractometric technique at 294 K with a least monophosphates that do not involve any other transition square refinement based upon 25 reflections with 18h22°.element than molybdenum. Among these hydroxyphosphates, The systematic absences l=2n+1 for h0l and k=2n+1 for only one, Na3[Mo2O4(HPO4) (PO4)],6 does not contain other 0k0 are consistent with the space group P21/c. The data were univalent cations such as phosphonium, ammonium or collected with an Enraf Nonius CAD4 diVractometer, and oxonium.We report on the synthesis and crystal stucture of a parameters are reported in Table 1. Among the 9460 unique new molybdenum(V) hydroxymonophosphate Na8(Mo2O4- measured reflections, 3896 with I3s(I) corrected for Lorentz OH)3(PO4)3(PO3OH)·12.25H2O, with an original structure. and polarization and absorption and secondary extinction eVects were used to solve and refine the structure.The atoms Synthesis procedure were located by the heavy atom method, i.e. the molybdenum atoms were located by the deconvolution of the Patterson Single crystals of the title compound were grown from a hydrothermal reaction of H3PO4 (Prolabo, 75%), NaOH function and the other atoms by subsequent Fourier synthesis.J. Mater. Chem., 1998, 8(2), 439–444 439Table 1 Summary of crystal data, intensity measurements and structure Table 2 Positional parameters and their estimated standard deviationsa refinement parameters for Na8Mo6P4O27(OH)4·12.25H2O atom x y z B/A ° 2 crystal data: space group P21/c Mo(1) 0.6111(1) 0.39072(7) 0.7077(1) 1.00(6) Mo(2) 0.3980(2) 0.39170(7) 0.6374(1) 1.02(6) cell dimensions a=13.024(4) A ° b=25.936(4) A ° b=111.72(2)° Mo(3) 0.2416(1) 0.41456(7) 0.3596(1) 1.15(6) Mo(4) 0.3438(2) 0.43037(7) 0.2277(1) 1.18(6) c=13.276(3) A ° volume/A ° 3 4116.1(7) Mo(5) 0.6362(2) 0.42959(7) 0.3236(1) 1.18(6) Mo(6) 0.7485(2) 0.41246(7) 0.5275(1) 1.14(6) Z 4 Dc/g cm-3 2.51 P(1) 0.4947(5) 0.3531(2) 0.4404(5) 0.96(2) P(2) 0.1888(5) 0.3142(2) 0.4946(5) 1.36(2) intensity measurements: P(3) 0.4798(5) 0.3882(2) 0.0782(5) 1.84(2) l(Mo-Ka) 0.71073 P(4) 0.8126(5) 0.3127(2) 0.7029(5) 1.68(2) scan mode v–2/3h Na(1) 1/2 1/2 1/2 1.20(3) scan width/° 1.5+0.35 tanh Na(2) 0.4936(8) 0.2330(3) 0.2970(7) 2.48(3) slit aperture/mm 1.3+tanh Na(3) 0.483(1) 0.2512(4) 0.067(1) 6.40(6) max h/° 27 Na(4) 0.1152(8) 0.1993(4) 0.3428(8) 3.60(4) standard reflections three measured every 3600 s Na(5) 0.7212(8) 0.2807(4) 0.4589(8) 3.28(4) measured reflections 9460 Na(6) 0.2774(8) 0.2855(4) 0.3108(8) 2.72(3) reflections with I>3s 3896 Na(7) 0.569(1) 0.0232(4) 0.430(1) 6.32(6) h min., max.-16, 16 Na(8) 0.956(1) 0.4686(5) 0.378(1) 5.60(5) k min., max. 0, 33 Na(9)b 0.827(5) 0.141(2) 0.486(4) 6.40(2) l min., max. 0, 16 Na(10)b 0.109(4) 0.037(2) 0.440(4) 6.40(2) m/mm-1 2.11 O(1) 0.638(1) 0.4122(6) 0.835(1) 1.84(5) O(2) 0.503(1) 0.3346(5) 0.683(1) 1.68(5) structure solution and refinement: parameters refined 507 O(3) 0.505(1) 0.4419(5) 0.625(1) 1.12(4) O(4) 0.732(1) 0.3363(5) 0.751(1) 1.68(5) agreement factors R=0.055 Rw=0.066 weighting scheme w=1/s2 O(5) 0.726(1) 0.4341(6) 0.669(1) 1.68(5) O(6) 0.602(1) 0.3689(6) 0.538(1) 0.88(4) D/s max.<0.005 O(7) 0.377(1) 0.4114(6) 0.747(1) 2.32(6) O(8) 0.278(1) 0.4392(5) 0.522(1) 0.80(4) O(9) 0.276(1) 0.3384(5) 0.599(1) 1.28(5) All the calculations were done on a Spark station with the O(10) 0.396(1) 0.3687(5) 0.470(1) 1.20(4) O(11) 0.124(1) 0.4485(6) 0.302(1) 2.00(5) XTAL package.9 Full crystallographic details, g O(12) 0.260(1) 0.3719(5) 0.247(1) 1.44(5) structure factors, have been deposited at the Cambridge O(13) 0.354(1) 0.4639(5) 0.363(1) 1.12(4) Crystallographic Data Centre (CCDC).See Information for O(14) 0.169(1) 0.3522(5) 0.400(1) 1.68(5) Authors, J. Mater. Chem., 1998, Issue 1. Any request to the O(15) 0.257(1) 0.4687(5) 0.133(1) 1.92(5) CCDC for this material should quote the full literature citation O(16) 0.381(1) 0.3836(5) 0.119(1) 1.60(5) and the reference number 1145/71.O(17) 0.491(1) 0.4727(5) 0.247(1) 1.44(5) O(18) 0.491(1) 0.3852(5) 0.342(1) 1.20(4) The molybdenum, phosphorus, oxygen atoms O(1)–O(31) O(19) 0.725(1) 0.4648(6) 0.291(1) 2.32(6) and Na(1) were identified without any ambiguity. The distinc- O(20) 0.589(1) 0.3858(5) 0.184(1) 1.68(5) tion between the sodium atoms [Na(2)–Na(10)] and the water O(21) 0.636(1) 0.4640(5) 0.456(1) 1.36(5) molecules [O(32)–O(46)] was diYcult, owing to the same O(22) 0.722(1) 0.3701(5) 0.399(1) 1.60(5) number of electrons of the two species.The identification of O(23) 0.866(1) 0.4451(5) 0.543(1) 1.68(5) the diVerent species was performed on the basis of the O(24) 0.826(1) 0.3494(5) 0.614(1) 1.44(5) O(25) 0.492(1) 0.2962(5) 0.420(1) 1.28(5) interatomic distances and the coordination of each atom.The O(26) 0.229(1) 0.2645(5) 0.468(1) 2.24(6) refinement of the isotropic thermal factors and the occupancy O(27) 0.079(1) 0.3099(6) 0.515(1) 2.32(6) factors, coupled with the ratios between the height of the O(28) 0.476(1) 0.3402(6) 0.013(1) 2.56(6) Fourier peaks allowed first to distribute 0.25 Na+ in the Na(9) O(29) 0.469(1) 0.4377(6) 0.019(1) 2.72(6) and Na(10) sites, 0.5 H2O in the O(42), O(43), O(44) and O(30) 0.766(1) 0.2612(6) 0.649(1) 2.96(6) O(45) sites and one 0.25 H2O in the O(46) site.Then in the O(31) 0.925(1) 0.3070(8) 0.799(1) 4.08(6) H2O(32) 0.065(1) 0.1346(6) 0.183(1) 2.40(3) following refinement the occupancy factors were fixed.The H2O(33) 0.321(1) 0.1949(6) 0.324(1) 2.64(3) refinement of the atomic coordinates, the isotropic thermal H2O(34) 0.357(1) 0.2788(6) 0.160(1) 2.96(4) factors of the water molecules and incompletely occupied H2O(35) 0.925(1) 0.3772(6) 0.354(1) 3.2(4) sodium sites, and the anisotropic thermal factors of the remain- H2O(36) 0.086(1) 0.0470(6) 0.057(1) 3.12(4) ing atoms led to R=0.055 and Rw=0.066 and to the atomic H2O(37) 0.625(1) 0.2780(6) 0.243(1) 3.04(4) parameters listed in Table 2.As the compound was synthesized H2O(38) 0.890(1) 0.2550(7) 0.447(1) 3.92(4) H2O(39) 0.102(1) 0.2594(7) 0.190(1) 3.44(4) by hydrothermal reaction with an excess of sodium hydroxide, H2O(40) 0.642(1) 0.1943(7) 0.445(1) 3.76(4) hydroxy groups were susceptible to be present in the structure.H2O(41) 0.901(2) 0.319(1) 0.158(2) 8.32(7) Thus, a calculation of the electrostatic bond strength balance H2O(42)c 0.151(2) 0.137(1) 0.478(2) 2.32(6) was performed, using the Brese and O’KeeVe formulation10 for H2O(43)c 0.738(3) 0.433(2) 0.076(3) 4.80(8) MoV, Na and PV species (rij=1.879, 1.80, 1.604, respectively) H2O(44)c 0.266(3) 0.047(2) 0.378(3) 5.60(8) and the Brown curves11 for the hydrogen bonds.A lack of ca. H2O(45)c 0.936(3) 0.069(2) 0.338(3) 4.80(8) H2O(46)b 0.091(4) 0.995(2) 0.308(4) 1.60(8) 0.7 in the electrostatic valence of an oxygen atom is characteristic of an hydroxy group and a lack of ca. 1.4 indicates a aAnisotropically refined atoms are given in the form of the isotropic water molecule. The O(32)–O(46) sites identified as water equivalent displacement parameter defined as B=4/3SiSjaiajbij.Water molecules during the resolution of the structure receive about molecules refined isotropically. 0.262 electrostatic valence from the Mo, P or Na atoms. Five bOccupancy=0.25. oxygen sites O(5), O(8), O(17), O(31) and O(27) receive, cOccupancy=0.5. respectively, 1.150, 1.033, 1.159, 1.380 and 1.180 electrostatic valence from the Mo, P or Na atoms. However, O(27) receives only 0.673 more electrostatic valence from the four water molecules O(32), O(35), O(38) and O(39).Thus it can be concluded that O(5), O(8), O(17) and O(31) are hydroxy 440 J. Mater. Chem., 1998, 8(2), 439–444groups so that three OH groups belong to the MoO6 octahedra phosphate the structure of each cluster consists of two rings of six Mo(O5OH) edge-sharing octahedra; each Mo6 ring and one OH group to the PO4 tetrahedra.The water loss deduced from thermogravimetry is consistent with 28.5 H shares its apices with three PO4 tetrahedra [two tetrahedra P(2) and P(3) at the periphery of the cluster and one central atoms per formula. From these observations this compound can be formulated Na8(Mo2O4OH)3(PO4)3(PO3OH)·12.25 phosphate group P(1)] and one P(O3OH), P(4).The two Mo6 rings are connected through one NaO6 octahedron Na(1) that H2O. The theoretical valency of five for molybdenum is confirmed by the bond strength calculations which lead to valencies of 4.85, 5.03, 4.81, 4.75, 4.95 and 4.93 respectively for Table 3 Distances (A ° ) and angles (°) in the polyhedra the six molybdenum atoms.Mo(1) O(1) O(2) O(3) O(4) O(5) O(6) O(1) 1.69(2) 2.93(2) 2.79(2) 2.76(2) 2.89(2) 3.96(2) Description of the structure and Discussion O(2) 106.6(7) 1.96(1) 2.89(2) 2.77(2) 3.93(2) 2.82(2) O(3) 100.5(6) 95.6(6) 1.94(1) 3.91(2) 2.72(2) 2.76(2) The projection of the structure of this new molybdenum(V) O(4) 95.3(6) 87.8(6) 162.1(7) 2.03(1) 2.75(2) 2.83(2) hydroxymonophosphate along a (Fig. 1) shows that it consists O(5) 99.6(7) 153.1(7) 85.1(6) 84.0(6) 2.08(2) 2.53(2) of centrosymmetric clusters Na[Mo6P4O27(OH)4]2 intercon- O(6) 170.0(6) 82.9(6) 81.1(5) 81.9(5) 70.7(5) 2.29(1) nected through sodium cations and water molecules. Mo(2) O(2) O(3) O(7) O(8) O(9) O(10) Each Na[Mo6P4O27(OH)4]2 cluster (Fig. 2) is very similar O(2) 1.96(1) 2.89(2) 2.90(2) 3.99(2) 2.76(2) 2.79(2) to the Na[Mo12P4O24(OH)7] clusters observed for the O(3) 95.0(6) 1.96(1) 2.83(2) 2.76(2) 3.93(2) 2.78(2) phosphate polymer (H3O)2NaMo6P4O24(OH)7(PPh4)2·5H2O, O(7) 106.7(7) 102.8(7) 1.65(2) 2.87(2) 2.69(2) 3.94(2) whose structure has been described by Haushalter and Lai.5 O(8) 154.5(6) 84.9(5) 98.1(6) 2.13(1) 2.81(2) 2.64(2) Nevertheless the clusters of the two structures diVer from O(9) 87.6(6) 161.8(6) 93.7(7) 85.1(5) 2.03(1) 2.83(2) O(10) 81.7(6) 81.0(5) 170.1(6) 73.1(5) 81.5(6) 2.30(1) each other by the distribution and the number of protons.Haushalter and Lai5 observe fourteen OH groups per cluster, Mo(3) O(8) O(10) O(11) O(12) O(13) O(14) instead of eight in the present compound. Moreover in the O(8) 2.12(1) 2.64(2) 2.88(2) 3.97(2) 2.72(2) 2.83(2) O(10) 72.6(5) 2.33(1) 3.99(2) 2.83(2) 2.79(2) 2.78(2) Haushalter phase all OH groups are assumed to be linked to O(11) 97.4(6) 168.8(7) 1.69(1) 2.93(2) 2.84(2) 2.78(2) the phosphorus forming seven PO3(OH) tetrahedra per cluster, O(12) 154.9(5) 82.4(5) 107.3(6) 1.94(2) 2.86(2) 2.75(2) in contrast with the present structure where six OH groups O(13) 84.0(6) 81.5(5) 102.8(6) 94.8(6) 1.94(1) 3.92(2) per cluster are linked to molybdenum, forming MoO5(OH) O(14) 85.5(6) 78.7(5) 95.9(7) 87.3(6) 159.6(5) 2.04(2) octahedra, and only two OH groups are linked to phosphorus Mo(4) O(12) O(13) O(15) O(16) O(17) O(18) [P(4)] forming PO3(OH) tetrahedra.Then in our hydroxy- O(12) 1.94(2) 2.86(2) 2.93(2) 2.74(2) 3.98(2) 2.82(2) O(13) 94.5(6) 1.95(1) 2.84(2) 3.98(2) 2.76(2) 2.78(2) O(15) 108.1(6) 103.2(6) 1.67(1) 2.78(2) 2.86(2) 3.92(2) O(16) 85.7(6) 160.8(5) 95.0(7) 2.08(2) 2.91(2) 2.77(2) O(17) 155.2(5) 84.6(6) 96.2(6) 87.3(6) 2.14(2) 2.60(2) O(18) 83.4(5) 82.1(5) 166.7(7) 78.9(5) 71.9(5) 2.28(1) Mo(5) O(17) O(18) O(19) O(20) O(21) O(22) O(17) 2.11(1) 2.60(2) 2.88(2) 2.86(2) 2.73(2) 3.96(2) O(18) 71.9(5) 2.31(2) 3.94(2) 2.83(3) 2.82(2) 2.85(2) O(19) 99.7(7) 170.3(6) 1.65(2) 2.74(2) 2.82(3) 2.85(2) O(20) 86.7(5) 80.5(6) 94.3(7) 2.07(1) 3.99(2) 2.77(2) O(21) 84(1) 0 82.2(6) 102.2(7) 162.2(6) 1.97(1) 2.89(2) O(22) 155.4(6) 83.6(6) 104.5(7) 87.2(6) 95.0(6) 1.95(1) Mo(6) O(5) O(6) O(21) O(22) O(23) O(24) O(5) 2.08(2) 2.53(2) 2.74(2) 3.93(2) 2.90(2) 2.78(2) O(6) 71.1(5) 2.26(1) 2.80(2) 2.82(2) 3.93(2) 2.75(2) O(21) 85.6(6) 82.9(6) 1.95(1) 2.89(2) 2.82(2) 3.93(2) O(22) 154.4(6) 83.8(6) 95.9(6) 1.95(1) 2.88(2) 2.72(2) O(23) 100.1(7) 170.0(6) 101.3(6) 104.6(7) 1.69(1) 2.77(2) O(24) 85.0(6) 79.3(5) 161.8(7) 86.1(6) 95.7(6) 2.04(1) P(1) O(6) O(10) O(18) O(25) O(6) 1.57(1) 2.50(2) 2.51(2) 2.53(2) Fig. 1 Projection of the structure of Na8(Mo2O4OH)3(PO4)3- O(10) 107.5(8) 1.53(2) 2.48(2) 2.48(2) (PO3OH) along a O(18) 107.5(8) 107.8(8) 1.54(2) 2.53(2) O(25) 111.2(7) 109.9(9) 112.8(9) 1.50(1) P(2) O(9) O(14) O(26) O(27) O(9) 1.56(1) 2.51(2) 2.51(2) 2.50(2) O(14) 108.1(8) 1.54(2) 2.46(2) 2.49(2) O(26) 110.7(8) 109(1) 1.48(2) 2.55(2) O(27) 106.7(9) 107.7(9) 114(1) 1.55(2) P(3) O(16) O(20) O(28) O(29) O(16) 1.57(2) 2.52(2) 2.46(3) 2.48(2) O(20) 105.9(9) 1.58(1) 2.50(2) 2.55(2) O(28) 106.2(9) 107.7(8) 1.51(2) 2.53(2) O(29) 109(1) 112.4(9) 116(1) 1.48(2) P(4) O(4) O(24) O(30) O(31) O(4) 1.55(2) 2.56(2) 2.51(2) 2.48(2) O(24) 110.4(9) 1.57(2) 2.51(2) 2.56(2) O(30) 109(1) 108.2(9) 1.53(2) 2.57(2) O(31) 106(1) 110(1) 113(1) 1.55(2) Mo(1),Mo(2) 2.581(3). Mo(2),Mo(3) 3.541(3).Mo(3),Mo(4) 2.594(3). Mo(4),Mo(5) 3.541(3). Fig. 2 Na[Mo6P4O27(OH)4]2 cluster Mo(5),Mo(6) 2.595(3).Mo(6),Mo(1) 3.524(3). J. Mater. Chem., 1998, 8(2), 439–444 441Fig. 3 Projection of the structure of Na8(Mo2O4OH)3- (PO4)3(PO3OH)·12.25H2O along c shares three apices with each of them. Thus these clusters can be formulated Na[(Mo2O4OH)3(PO4)3(PO3OH)]2. Similarly to (H3O)2NaMo6P4O24(OH)7(PPh4)2·5H2O, each Mo octahedron has one free apex characteristic of MoV. Note also that in our phase the OH groups of the MO5(OH) octahedra are always shared by two octahedra.The presence of OH groups linked to molybdenum in the Na[Mo6P4O27(OH)4]2 cluster is unusual so making direct comparison with the structures of Haushalter et al. may be of limited value since the hydrogen atoms were not localised but only assumed to be linked to the phosphate groups. Recent work on Na2Cd3(Mo2O4OH) 6 (PO4) 2 (PO3OH)6[N (CH3) 4] 4·10H2O and Cd9(Mo2O4OH)12(PO4)6(PO3OH)10[N(CH3)4]8·15H2O12 Table 4 NaMO distances<3.2 A° a Na(1)MO(3) 2.23(1) Na(6)MO(12) 2.38(2) Na(1)MO(3)i 2.23(1) Na(6)MH2O(33) 2.41(2) Na(1)MO(13) 2.29(1) Na(6)MO(26) 2.46(2) Na(1)MO(13)i 2.29(1) Na(6)MH2O(34) 2.58(2) Na(1)MO(21) 2.27(1) Na(6)MO(25) 2.64(2) Na(1)MO(21)i 2.27(1) Na(6)MO(14) 2.76(2) Na(2)MO(25) 2.32(2) Na(6)MO(10) 3.01(2) Na(2)MO(2)ii 2.35(2) Na(7)MO(29)v 2.29(2) Na(2)MH2O(34) 2.34(2) Na(7)MO(29)iv 2.42(2) Na(2)MH2O(37) 2.39(2) Na(7)MO(1)ii 2.46(2) Na(2)MH2O(40) 2.41(2) Na(7)MO(17)iv 2.55(2) Na(2)MH2O(33) 2.60(2) Na(7)MH2O(43)v 2.59(2) Na(3)MO(25)ii 2.34(2) Na(7)MO(15)iv 3.03(2) Na(3)MO(28) 2.41(2) Na(7)MH2O(44)vi 3.22(2) Na(3)MH2O(34) 2.49(3) Na(7)MO(7)ii 3.25(2) Na(3)MH2O(37) 2.49(2) Na(8)MH2O(36)iv 2.35(2) Na(3)MO(2)ii 2.66(2) Na(8)MH2O(36)x 2.38(2) Na(3)MO(26)ii 3.09(2) Na(8)MH2O(35) 2.40(2) Na(4)MO(31)iii 2.33(2) Na(8)MH2O(46)iv 2.41(2) Na(4)MH2O(42) 2.34(2) Na(8)MO(11)vii 2.78(2) Na(4)MO(26) 2.45(2) Na(8)MO(19) 2.80(2) Na(4)MH2O(39) 2.51(2) Na(8)MO(23) 2.91(2) Na(4)MH2O(32) 2.59(2) Na(8)MO(23)viii 3.12(2) Na(4)MH2O(33) 2.78(2) Na(9)MH2O(41)v 2.36(2) Na(5)MH2O(38) 2.36(2) Na(9)MH2O(40) 2.64(2) Fig. 4 The surrounding of the sodium cations Na(5)MO(30) 2.42(2) Na(9)MH2O(43)v 2.75(2) Na(5)MO(22) 2.45(2) Na(9)MO(1)ii 2.89(2) Na(5)MH2O(40) 2.45(2) Na(9)MO(4)ii 2.96(2) show also the presence of six OH linked to molybdenum Na(5)MO(6) 3.15(2) Na(9)MH2O(38) 3.15(2) in the clusters. Na(5)MH2O(37) 2.67(2) Na(10)MH2O(45)xi 2.31(2) Na(5)MO(24) 2.68(2) Na(10)MH2O(44) 2.48(2) In these condensed polyanions, the geometry of the Na(5)MO(25) 2.86(2) Na(10)MO(15)v 2.58(2) MoO5(OH) octahedra is characteristic of that encountered for Na(6)MH2O(39) 2.35(2) Na(10)MH2O(42) 2.65(2) MoV.As observed in Table 3, abnormally short MoMO bonds ranging from 1.65 to 1.69 A ° are observed corresponding to the aSymmetry codes: i: 1-x, 1-y, 1-z; ii: x, 1/2-y, z-1/2; iii: x-1, free apex, opposite very long MoMO bonds, ranging from 2.26 1/2-y, z-1/2; iv: 1-x, y-1/2. 1/2-z; v: x, 1/2-y, z+1/2; vi: 1-x, to 2.33 A ° , and four intermediate equatorial MoMO bonds, -y, 1-z; vii: 1+x, y, z; viii: 2-x, 1-y, 1-z; ix: 1+x, 3/2-y, 3/2+z; x: 1+x, 1/2-y, 1/2+z; xi: x-1, y, z.ranging from 1.94 to 2.14 A ° . Nevertheless a distinction can be 442 J.Mater. Chem., 1998, 8(2), 439–444made for the equatorial MoMO distances: smaller distances (1.94–1.97 A ° ) correspond to oxygen atoms bridging two octahedra, intermediate distances (2.03–2.08 A ° ) characterize the MoMOMP bonds, whereas larger MoMO bonds (2.08–2.14 A ° ) characterize the hydroxy groups bridging two Mo octahedra, i.e. MoMOHMMo. With PMO distances ranging from 1.48–1.58 A ° (Table 3) the monophosphate groups are less regular than observed in many monophosphates.The shortest PMO distances (1.48–1.53 A ° ) are due to the fact that the corresponding oxygen atom is free, whereas the longer ones correspond either to PMOMH or to PMOMMo bonds. The Na(1) octahedron that ensures the junction between two Mo6 rings exhibits a remarkable regular octahedral coordination with six NaMO distances ranging from 2.23–2.29 A ° (Table 4).The MoMMo distances in the Mo6 clusters (Table 3), ranging from 2.581–2.595 A ° and from 3.524–3.541 A ° are very similar to those observed for (H3O)2NaMo6P4O24(OH)7- (PPh4)2·5H2O, suggesting the existence of some strong MoMMo interactions. The great diVerence between this phase and that described by Haushalter and Lai5 deals with the relative position of the molybdenum clusters and with their connection through Na+ cations. In (H3O)2NaMo6P4O24(OH)7, the molybdenum clusters are linked through Na+ cations, along one direction only forming one dimensional chains,5 whereas in Na8(Mo2O4OH)3(PO4)3(PO3OH)·12.25H2O the Na+ cations form a three-dimensional network with the Na[Mo6P4O27(OH)4]2 clusters.Fig. 1 shows that Na(2) forms indeed one NaMOMP bond with one cluster and one NaMOMMo bond with another cluster, that Na(3) shares two bonds, NaMOMP bond with the same cluster and forms one NaMOMP bond with another cluster, whereas Na(4) forms one NaMOMP bond with one cluster and a second one with another cluster, and Na(7) is connected to two diVerent clusters through two NaMOMMo and two NaMOMP bonds, respectively.In the same way, the projection of the structure along c (Fig. 3) shows that Na(8) ensures the connection between two clusters, forming one NaMOMMo bond with one unit and two NaMOMMo bonds with a second unit. By contrast, atoms Na(5), Na(6), Na(9) and Na(10) form NaMO bonds within the same cluster only so that such ions do not participate to the cohesion of the framework, at least from the viewpoint of strong NaMOMP or NaMOMMo bonds.We can consider this structure as a mixed framework ‘Mo–P–Na–O’ built up only of octahedra and tetrahedra. In such a description, the Na(2), Na(3) and Na(4) cations that, like Na(1), exhibit an octahedral coordination, are suYcient to construct a tridimensional framework with the Na[Mo6P4O27(OH)4]2 clusters.In the latter, the Na+ cations Fig. 6 Tunnels running along a (a), b (b), c (c) Na(5), Na(6), Na(7), Na(8), Na(9) and Na(10) which exhibit a diVerent coordination can then be considered as interpolated cations. The Na(2) and Na(4) atoms form Na(H2O)4O2 octahedra [Fig. 4(a,c)] with NaMO distances ranging from 2.32–2.78 A ° (Table 4) whereas more distorted Na(H2O)2O4 octahedra [Fig. 4(b)] are observed for Na(3) with NaMO distances ranging from 2.34–3.09 A ° (Table 4). Such Na(H2O)4O2 and Na(H2O)2O4 octahedra share their apices and edges to form disconnected chains running along c, at y#0.25 (Fig. 5); the association of the Na(H2O)4O2 and Na(H2O)2O4 octahedra with the Na[Mo6P4O27(OH)4]2 clusters, by sharing corners and edges, leads to the formation of large tunnels running along a [Fig. 6(a)], b [Fig. 6(b)] and c [Fig. 6(c)] so that this hydroxymonophosphate can also be described as an Fig. 5 Chains of NaO6 octahedra running along c at y=1/4 intersecting tunnel structure. J. Mater. Chem., 1998, 8(2), 439–444 443In such an intersecting tunnel structure the Na(5), Na(6) and and the presence of OH groups not only on the P tetrahedra but also on the Mo octahedra.Na(8) cations form bicapped triangular prisms, Na(H2O)3O5 [Fig. 4(d,e)] and Na(H2O)4O4 [Fig. 4(g)] respectively, with Based on these observations, it should be possible to synthesize many other molybdenum(V) hydroxymonophos- seven NaMO distances ranging from 2.35 to 2.91 A° , the eight NaMO bonds being >3 A° (3.01–3.15 A ° ); it is noted that two phates with microporous properties by associating Na+ with larger univalent cations, such as rubidium, caesium or adjacent Na(8) polyhedra share one face.The Na(7) cations exhibit a strongly distorted cubic coordination [Fig. 4( f )] with alkyl/arylammonium ions. two adjacent Na(H2O)2O6 cubes sharing one edge. The Na(9) and Na(10) sites are only partially occupied (Table 2). These References cations that form bonds with only one Na[Mo6P4O27(OH)4]2 cluster have their ligands displayed on the same side with 1 R.C. Haushalter and L. A. Mundi, Chem.Mater. 1992, 4, 31. 2 G. Costentin, A. Leclaire, M-M. Borel, A. Grandin and B. Raveau, respect to Na+; in the polyhedra Na(H2O)4O2 [Fig. 4(h)] and Rev. Inorg. Chem., 1993, 13, 77.Na(H2O)3O [Fig. 4(i )], the interatomic NaMO distances range 3 R. Peascoe and A. Clearfield, J. Solid State Chem., 1991, 95, 289. from 2.31–3.15 A° . 4 K. Kasthuri Rangan and J. Gopalakrishnan, Inorg. Chem., 1996, In conclusion, a new sodium molybdenum hydroxymono- 35, 6080. phosphate has been synthesized. It is to our knowledge 5 R. C. Haushalter and F. W. Lai, Inorg.Chem., 1989, 28, 2904. an unusual molybdenum(V) hydroxyphosphate that contains 6 L. A. Mundi and R. C. Haushalter, Inorg. Chem., 1990, 29, 2879. 7 R. C. Haushalter and F. W. Lai, Angew. Chem., Int. Ed. Engl., 1989, only sodium as a univalent interpolated cation, the only 28, 743. other example being Na3[Mo2O4(HPO4) (PO4)]·2H2O6 which 8 L. A. Mundi, L. Yacullo and R. C. Haushalter, J. Solid State Chem., exhibits a layer structure. The presence of clusters 1991, 95, 283. A[Mo6P4O31Hn]2 seems to be a characteristic of molyb- 9 Xtal3.2 Reference Manual, ed. S. R. Hall, H. D. Flack, denum(V) hydroxyphosphates, since it has previously been J. M. Stewart, Universities of Western Australia, Australia, observed in several compounds with Na or Fe or Zn, viz. Geneva, Switzerland and Maryland. 10 N. E. Brese and M. O’KeeVe, Acta Crystallogr., Sect. B. 1991, (Et4N)6Na2[Na12(H3PO4){Mo6O15(HPO4) (H2PO4)3}]·xH2O,7 47, 192. (PPh4)2[(H3O)2NaMo6P4O24(OH)7]·5H2O,5 [(CH3)4N]2- 11 I. D. Brown, Acta Crystallogr., Sect. A. 1976, 32, 24. (H3O)2[Zn3Mo12O30(HPO4)2(H2PO4)6]·11.5H2O,13 12 A. Guesdon, M. M. Borel, A. Leclaire and B. Raveau, Chem. Eur. [(CH3)4N]2(NH4)2[Fe2Mo12O30(H2PO4)6(HPO4)2]·nH2O,14 J., 1997, 3, 1797. and [(CH3)4N]2Na4[Fe3Mo12O30(HxPO4)8]·nH2O.14 13 L. A. Mundi and R. C. Haushalter, Inorg. Chem., 1992, 31, 3050. Two important features characterize this original structure: 14 L. A. Meyer and R. C. Haushalter, Inorg. Chem., 1993, 32, 1579. its three-dimensional mixed framework built up of Mo and Na octahedra and P tetrahedra that forms intersecting tunnels Paper 7/07568E; Received 20th October, 1997 444 J. Mater. Chem., 1998, 8(2), 439–444