J O U R N A L O F C H E M I S T R Y Materials Radical salts of the organic donor BET-TTF† with polyoxometalate clusters‡ Eugenio Coronado,*a Jose� R. Gala�n-Mascaro�s,a Carlos Gime�nez-Saiz,a Carlos J. Go�mez-Garcý�a,a Concepcio� Rovira,*b Judit Tarre�s,b Smail Trikia§ and Jaume Vecianab aDepartamento de Quý�mica Inorga�nica, Universidad de Valencia, E-46100 Burjasot, Spain bInstitut Ciencia deMaterials de Barcelona, CSIC, Campus de la U.A.B., E-08193 Bellaterra, Spain The synthesis, structures and physical characterizations of the first radical ion salts of the organic donor BET-TTF 1 with polyoxometalate clusters ([M6O19]2-; M=WVI, MoVI, 2) are reported.The 251 salts (BET-TTF+)2[M6O19]2- are formed by pairs of the BET-TTF+ radical cations surrounded by polyanions so as to form a 3D packing of anions and cations with short intermolecular contacts between the cation pairs.The synthesis, physical properties and main structural features of the first radical ion salts of the organic donor BET-TTF 1 with the polyoxometalate cluster [SiW12O40]4- 3 are also reported. The 451 salt (BET-TTF+)4[SiW12O40]4- is formed by a 2D hexagonal packing of anions and by isolated BET-TTF+ pairs.The compounds are insulators and diamagnetic. A current approach to obtaining new molecular conductors more than one compound can be formed in the same experiment. Despite this intrinsic diYculty we show herein that consists of combining organic electron donor molecules with large cluster anions. The so-called polyoxometalates oVer radical salts of 1 of suYcient quality for structural and physical characterization can be obtained using polyoxometalate clus- interesting structural and electronic characteristics in this context.1 ters as counterions.(i) These soluble metal–oxides show diVerent sizes, shapes and charges which are maintained in aqueous and non-aqueous Results and Discussion solvents as well as in the solid state.These features can induce new packings in the molecular constituents of the conducting The radical salts of BET with the Lindqvist anions [M6O19]2- (M=W and Mo) 4 and 5 part, leading to new band structures and therefore to unusual electrical properties.1,2 The two salts containing the [M6O19]2- anions were obtained (ii) They can have a magnetic character when they accommoas single crystals by electrocrystallization. Both salts are isodate magnetic ions or clusters in the structure, or when they structural and crystallize in the triclinic system P19 (see Table 1).act as electron acceptors giving rise to delocalized mixed- The unit cell is displayed in Fig. 1(a) and contains two BET valence clusters. These electronic features provide the opporcrystallographically equivalent molecules and one Lindqvist tunity to create systems combining magnetic and conducting anion located in the apexes of the unit cell.properties.3 The BET molecules present a disorder aVecting the sulfur The examples so far reported of organic donor–inorganic atoms external to the TTF core which are disordered over two cluster hybrids are almost exclusively based on the combination diVerent positions. These sites have a multiplicity of 0.5 for C of commercially available tetrathiafulvalene (TTF) or bis(ethyand 0.5 for S.This disorder may be due to the presence of two lenedithio)-TTF (BEDT-TTF or ET) with polyoxometalates diVerent orientations of the pure trans isomer of the BET having metal nuclearities of six (Lindqvist [M6O19]2-; M= molecule (starting material), or maybe to the possible isomeriz- WVI, MoVI),2,4 eight (octamolybdate b-[Mo8O26]4-), twelve {Keggin [XM12O40](8-n)- (Xn+=PV, SiIV, BIII, Fe 3 +, 2H+, Co2+, Cu 2 +, etc.; M=WVI, MoVI}5 and eighteen (Wells– Table 1 Relevant intramolecular distances of the BET molecule in the Dawson [P2W18O62]6-).6 With the aim of extending these salts BET2[M6O19] and calculation of its charge Q using the formula of Guionneau et al.;10 Q=6.347-7.463{(b+c)-(a+d)} studies to other organic donors we have combined the molecule bis(ethylenethio)-TTF (in short BET 1) with Lindqvist 2 (W and Mo derivatives) and Keggin 3 ([SiW12O40]4- anion) polyoxometalates.This organic donor has shown a good ability to form conducting radical salts with simple S S S S S S a d c b monoanions7 such as for example XF6- (X=P, As, Sb) or compound a/A ° b/A ° c/A ° d/A ° Qcalc SCN- with enhanced structural and electronic dimensionalities and also with magnetic anions8 of the type FeCl4-. However, BET2[W6O19] 1.38(1) 1.73(1) 1.74(1) 1.33(2) 0.95 in most cases the salts of 1 do not crystallize properly and 1.73(1) 1.72(1) 1.35(2) 1.72(1) 1.70(1) † BET-TTF=bis(ethylenethio)tetrathiafulvalene. 1.72(1) 1.70(1) ‡ Presented at the 58th Okazaki Conference, Recent Development and Future Prospects of Molecular Based Conductors, Okazaki, BET2[MoO19] 1.392(5) 1.724(3) 1.726(3) 1.348(5) 1.07 Japan, 7–9 March 1997. 1.730(3) 1.731(4) 1.353(5) § Permanent address: Laboratoire de Chimie, Electrochimie 1.734(3) 1.719(3) Mole`culaires et Chimie Analytique, URA CNRS 322, Universite� de 1.719(3) 1.717(4) Bretagne Occidentale. F-29285 Brest Cedex, France.J. Mater. Chem., 1998, 8(2), 313–317 313Fig. 1 (a) View of the unit cell of the salts 4 and 5; (b) two views of a dimer of BET molecules in 4 and 5 ation in solution of the cis–trans species during the electrooxidation. 9 The BET molecules are associated forming centrosymmetric face to face dimers with short contacts between the central C and S atoms [C(1)MC(1) 3.34 A ° , S(2)MS(3) 3.47 A ° ] although they are not eclipsed [Fig. 1(b)]. These dimers are surrounding the polyoxoanions so as to form a compact packing of anions and cations which is reminiscent of that of the NaCl salt. Thus, in the (1019) plane we observe that anions and dimeric cations are alternating along the directions [101] and [19219] [Fig. 2(a)]. However, due to the tendency of the organic donors to stack, the BET dimers are not completely isolated but show short contacts with the neighbouring dimers. In the above plane the shortest contacts occur in the b direction and involves two sulfur atoms (distance d3 in Fig. 2). Strong interdimer interactions are also observed along the a direction [Fig. 2(b)]. In view of the stoichiometry 251 of 4 and 5 the organic molecules are expected to be completely ionized (charge +1). This can be confirmed from the correlation between the intramolecular distances of the TTF skeleton and the oxidation degree Q proposed by Guionneau et al.10 for the BEDT–TTF molecule (see Table 2) that nicely fits to Q values of 0.95 and 1.07 for 4 and 5, respectively.A further support of this ionic charge is provided by the NIR–VIS spectra which exhibit a very strong and broad band centered at 7700 cm-1 which is Fig. 2 (a) View of the structure of 4 and 5 in the (1019) plane. Shortest intermolecular distances for 4 (5) in A ° : d1 [C(12)MC(12)]=3.69 (3.67), to be associated with the charge transfer between fully oxidized d2 [S(6)/C(8)MC(11)]=3.71 (3.71), d3 [S(6)/C(8)MC(8)/S(6)]=3.69 donors (B band), while the band associated with the electron (3.71), d4 [S(8)/C(10)MO(1)]=3.18 (3.16), d5 [C(11)MO(6)]=3.32 transfer between partially charged donors (A band) does not (3.29), d6 [S(4)MO(8)]=3.13 (3.12).(b) View of the structure in the appear.11 The IR spectrum is also typical of fully charged BET (012) plane.Shortest intermolecular distances for 4 (5) inA ° : d7 ions. In a mixed valence system broad bands associated with [S(7)/C(9)MS(1)]=3.53 (3.54), d8 [S(3)MS(3)]=3.61 (3.62), d9 the ag modes are observed in the region 800–1600 cm-1 arising [S(5)/C(7)MO(3)]=3.43 (3.42), d10 [O(3)MO(4)]=3.20 (3.21). from the coupling between delocalized electrons and vibrational modes of the double bonds.In the present case however only sharp bands are observed. The lack of a mixed charged BET molecules which have their spins antiferromagnetically coupled giving rise to a S=0 ground spin state. valence character in the organic part prevents the occurrence of electron delocalization. In fact, the transport properties Accoignal is observed in the EPR spectra of both salts.The thermal dependence of the intensity of this measured on single crystals (two-probe) indicate that both salts are insulators with low conductivity values [sRT= signal (proportional to the spin susceptibility) is plotted in Fig. 3. Note that this signal stays roughly constant in the 3.2×10-6 S cm-1] and high activation energies (Ea=240 meV in the range 240–300 K).The temperature dependent magnetic investigated temperature range. Such a behavior can not be attibuted to the exclusive presence of a paramagnetic impurity. susceptibility indicates that the two compounds are diamagnetic. This result is consistent with the dimerization of the The possibility of an excited triplet state thermally accessible 314 J. Mater. Chem., 1998, 8(2), 313–317Table 2 Crystallographic data for C20H16S12W6O19 4, C20H16S12Mo6O19 5 and C42H39NS24SiW12O42 6 chemical formula C20H16S12W6O19 C20H16S12Mo6O19 C42H39NS24SiW12O42 a/A ° 8.362(5) 8.352(6) 24.807(5) b/A° 10.925(6) 10.919(6) 24.194(5) c/A ° 11.664(4) 11.666(5) 14.357(3) a/degrees 65.28(3) 65.30(4) 90.00 b/degrees 79.11(2) 79.02(3) 90.00 c/degrees 80.73(3) 80.64(4) 90.00 V /A ° 3 946.5(8) 944.7(8) 8616.8(31) Z 1 1 3 M 2048.21 1520.75 4233.6(3) space group P19 (no. 2) P19 (no. 2) Pnma (no. 62) T /K 293(2) 293(2) 293(2) l/A ° 0.71073 0.71073 0.71073 Dc/g cm-3 3.593 2.673 3.704 m(Mo-Ka)/cm-1 18.896 2.672 24.248 R(F)a 0.0363 0.0228 0.0723 Rw(F)b 0.1214 0.0846 0.1937 aR=S[|Fo|-|Fc|]/S|Fo|; bRw=[Sw(|Fo|-|Fc|)2/Sw|Fo|2]1/2; w=4Fo2/[s2(|Fo|)-(0.07|Fo|2)].Fig. 3 Thermal dependence of the intensity of the EPR signal for the Fig. 4 View of the structure of 6 in the ac plane, showing the channels compounds BET2[W6O19] 4 and BET4[SiW12O40] 6 occupied by the disordered BET molecules BET molecules are occupying the hexagonal channels running can not be excluded. In fact, the data fit to the sum of a along the b axis created by the polyoxoanions.paramagnetic contribution, C/T , and a thermally activated Taking into account the stoiquiometry of 6 (451) and the contribution, (C¾/T ) exp(-J/kT ), with a coupling constant J charge of the anion [SiM12O40] (-4) the four BET molecules ca. 700 cm-1 and a 2% paramagnetic contribution. should be completely ionized (charge +1). This was confirmed by the absence of the characteristic ‘A’ band of mixed-valence The radical salt BET4[SiW12O40]·CH3CN·2H2O 6 species in the NIR spectrum.Accordingly the radical-cation salt is an insulator. The magnetic properties indicate a complete The preparation of radical salts of the BET donor with diVerent polyoxometalates having the Keggin structure {series coupling of the spins, which is in agreement with the association in dimers of the radical cations.In fact, the EPR spectra show [XM12O40] (X=PV, SiIV, BIII, Fe 3 +, 2H+, Co 2 +, Cu 2 +, etc.; M=W, Mo) and [XM(H2O)W11O39] (X=PV, SiIV; M=Ni2+, an extremely weak signal which, according to the thermal behavior, has to be attributed to the presence of a small Co2+, Cu2+, Cr3+, Fe3+)} was explored using the electrocrystallization technique.However, only the Si derivative gave amount of paramagnetic impurity (Fig. 3). single crystals suitable for a crystallographic study. The other polyanions do not gave any solid derivative and only in the Conclusions cases of PMo12 and PMnW11 was some powder deposited on the electrode. The first radical-cation salts of the electron donor molecule BET with Lindqvist and Keggin polyoxometalate clusters have Elemental analysis of 6 is consistent with the formula BET4[SiW12O40]·CH3CN·2H2O.Owing to the poor quality been prepared. The X-ray crystal structures of these salts show that in both cases the donor molecules are forming non- of the crystals only limited information about the crystal structure could be extracted by X-ray diVraction experiments. eclipsed dimers in the solid.However the diVerent size and charge of the two clusters have resulted in a diVerent packing Only the atoms of the Keggin anion as well as those of two of the four BET molecules could be found. The two remaining of these dimers with a significant extent of the intermolecular interactions in the Lindqvist derivatives, while quasi-insulated BET molecules are strongly disordered in the crystal and can not be localized (fragments of the central part of these mol- dimers are present in the Keggin derivative.Furthermore, EPR measurements suggest the presence of a thermally activated ecules have been localized in the Fourier maps). Fig. 4 shows a view of the structure in the ac plane. As we can see the triplet state in the [BET·+]2 dimers of the Lindqvist salts.In the reported salts the donor molecules have been found Keggin anions are forming hexagonal layers in this plane. The two BET molecules are located in between these anions and to be completely ionized and not surprisingly they are insulators with very low conductivity values. Compared with the are associated forming face to face dimers with a geometry which is similar to that found in the Lindqvist salts 4 and 5, equivalent BEDT–TTF radical salts we notice that a similar 251 insulating salt formed by [BEDT–TTF·+]2 dimers has but in this case the dimers are well isolated.The two disordered J. Mater. Chem., 1998, 8(2), 313–317 315Table 3 Atomic coordinates and isotropic or equivalent isotropic thermal parameters for the salt BET2[W6O19] atom x y z Ua /A ° 2 atom x y z Ua /A ° 2 W(1) 0.15295(5) 0.33787(4) -0.06422(4) 0.0274(1) C(3) 0.451(1) 0.179(1) 0.614(1) 0.031(2) W(2) -0.23398(5) 0.38887(4) 0.04408(4) 0.0293(1) C(4) 0.555(1) 0.194(1) 0.509(1) 0.034(2) W(3) 0.05657(5) 0.37228(4) 0.20745(4) 0.0275(1) C(5) 0.130(1) 0.764(1) 0.343(1) 0.032(2) O(1) 0.262(1) 0.2156(7) -0.1099(7) 0.040(2) C(6) 0.236(1) 0.780(1) 0.236(1) 0.035(2) O(2) 0.099(1) 0.2794(8) 0.3598(7) 0.042(2) C(7)b 0.4558(6) 0.0281(5) 0.7392(5) 0.045(1) O(3) -0.400(1) 0.3056(10) 0.0770(9) 0.051(2) C(8)b 0.6883(7) 0.0581(6) 0.5139(6) 0.052(1) O(4) -0.3089(9) 0.5414(7) 0.0887(7) 0.033(2) C(9)b -0.0158(5) 0.9004(4) 0.3318(4) 0.0281(8) O(5) -0.0668(9) 0.2821(7) -0.0183(7) 0.032(2) C(10)b 0.214(1) 0.9252(7) 0.1132(8) 0.078(2) O(6) 0.1671(9) 0.2662(7) 0.1130(7) 0.029(2) C(11) 0.618(2) -0.036(1) 0.667(2) 0.051(3) O(7) -0.075(1) 0.5284(7) 0.2196(7) 0.033(2) C(12) 0.023(2) 0.962(1) 0.166(2) 0.063(5) O(8) 0.232(1) 0.4833(7) 0.1315(7) 0.034(2) H(1)a 0.478(3) 0.034(1) 0.816(4) 0.050 O(9) -0.1413(9) 0.3062(7) 0.2004(7) 0.033(2) H(2)a 0.359(3) -0.019(1) 0.757(4) 0.050 O(10) 0.0000 0.5000 0.0000 0.024(2) H(3)a 0.672(3) 0.021(1) 0.455(4) 0.050 S(1) 0.3157(3) 0.3193(2) 0.6116(2) 0.0315(5) H(4)a 0.802(3) 0.076(1) 0.502(4) 0.050 S(2) 0.5486(3) 0.3477(3) 0.3815(3) 0.0356(6) H(5)a -0.126(3) 0.874(1) 0.367(4) 0.050 S(3) 0.1489(3) 0.6155(2) 0.4717(2) 0.0312(5) H(6)a 0.012(3) 0.960(1) 0.366(4) 0.050 S(4) 0.3809(3) 0.6501(3) 0.2409(2) 0.0334(5) H(7)a 0.226(3) 0.915(1) 0.033(4) 0.050 S(5)b 0.4558(6) 0.0281(5) 0.7392(5) 0.045(1) H(8)a 0.287(3) 0.989(1) 0.107(4) 0.050 S(6)b 0.6883(7) 0.0581(6) 0.5139(6) 0.052(1) H(9) 0.592(2) -0.121(1) 0.671(2) 0.050 S(7)b -0.0158(5) 0.9004(4) 0.3318(4) 0.0281(8) H(10) 0.708(2) -0.057(1) 0.716(2) 0.050 S(8)b 0.214(1) 0.9252(7) 0.1132(8) 0.078(2) H(11) -0.049(2) 0.924(1) 0.136(2) 0.050 C(1) 0.386(1) 0.4193(9) 0.4556(9) 0.028(2) H(12) -0.002(2) 1.059(1) 0.130(2) 0.050 C(2) 0.311(1) 0.5477(9) 0.396(1) 0.028(2) aUeq=(4/3)[a2B(1,1)+b2B(2,2)+c2B(3,3)+ab(cos c)B(1,2)+ac(cos b)B(1,3)+bc(cos a)B(2,3)]; H atoms with fixed U.bAtoms with multiplicity of 0.5. Table 4 Atomic coordinates and isotropic or equivalent isotropic thermal parameters for the salt BET2[Mo6O19] atom x y z Ua /A° 2 atom x y z Ua /A° 2 Mo(1) 0.15585(4) 0.33745(3) -0.06201(3) 0.03034(7) C(2) 0.3134(4) 0.5484(3) 0.3947(3) 0.0289(6) Mo(2) -0.23197(4) 0.38691(3) 0.04392(3) 0.03308(8) C(3) 0.4487(4) 0.1792(3) 0.6153(3) 0.0314(6) Mo(3) 0.05504(4) 0.37431(3) 0.20835(3) 0.03162(8) C(4) 0.5567(4) 0.1929(4) 0.5099(3) 0.0333(7) O(1) 0.2616(4) 0.2174(3) -0.1097(2) 0.0414(6) C(5) 0.1279(4) 0.7670(3) 0.3410(3) 0.0324(7) O(2) 0.0954(4) 0.2787(3) 0.3583(2) 0.0437(7) C(6) 0.2348(5) 0.7822(3) 0.2342(3) 0.0338(7) O(3) -0.3979(4) 0.3043(3) 0.0747(3) 0.0498(7) C(7)b 0.4562(2) 0.0280(2) 0.7409(2) 0.0502(4) O(4) -0.3100(3) 0.5403(3) 0.0910(2) 0.0350(5) C(8)b 0.690(1) 0.056(1) 0.513(1) 0.0476(4) O(5) -0.0667(3) 0.2834(2) -0.0232(2) 0.0347(5) C(9)b -0.014(1) 0.9002(9) 0.329(1) 0.0346(3) O(6) 0.1649(3) 0.2625(2) 0.1135(2) 0.0324(5) C(10)b 0.216(2) 0.928(1) 0.110(1) 0.0674(6) O(7) -0.0775(3) 0.5247(2) 0.2214(2) 0.0350(5) C(11) 0.6183(6) -0.0395(4) 0.6682(5) 0.055(1) O(8) 0.2362(3) 0.4809(3) 0.1310(2) 0.0359(5) C(12) 0.0224(2) 0.9645(2) 0.1649(2) 0.060(1) O(9) -0.1427(3) 0.3042(2) 0.2016(2) 0.0342(5) H(1)b 0.4799(2) 0.0342(2) 0.8165(2) 0.050 O(10) 0.0000 0.5000 0.0000 0.0253(6) H(4)b 0.672(1) 0.019(1) 0.454(1) 0.050 S(1) 0.3154(1) 0.31878(8) 0.61201(8) 0.0322(2) H(5)b 0.013(1) 0.9591(9) 0.364(1) 0.050 S(2) 0.5490(1) 0.3475(1) 0.38096(8) 0.0361(2) H(6)b -0.124(1) 0.8740(9) 0.363(1) 0.050 S(3) 0.1486(1) 0.61678(8) 0.47129(8) 0.0323(2) H(7)b 0.227(2) 0.917(1) 0.030(1) 0.050 S(4) 0.3807(1) 0.65015(9) 0.23974(8) 0.0340(2) H(8)b 0.290(2) 0.991(1) 0.103(1) 0.050 S(5)b 0.4562(2) 0.0280(2) 0.7409(2) 0.0502(4) H(9) 0.5887(6) -0.1231(4) 0.6709(5) 0.050 S(6)b 0.6903(2) 0.0571(2) 0.5136(2) 0.0476(4) H(10) 0.7077(6) -0.0633(4) 0.7181(5) 0.050 S(7)b -0.0152(2) 0.9025(2) 0.3304(2) 0.0346(3) H(11) -0.0496(2) 0.9261(2) 0.1352(2) 0.050 S(8)b 0.2135(2) 0.9290(2) 0.1114(2) 0.0674(6) H(12) -0.0032(2) 1.0619(2) 0.1300(2) 0.050 C(1) 0.3857(4) 0.4181(3) 0.4563(3) 0.0291(6) aUeq=(4/3) [a2B(1,1)+b2B(2,2)+c2B(3,3)+ab(cos c)B(1,2)+ac(cos b)B(1,3)+bc(cos a)B(2,3)]; H atoms with fixed U.bAtoms with multiplicity of 0.5. been found with the Lindqvist anions, although in this last Experimental case the structure is formed by alternating layers of the organic Synthesis donor and the anions,12 as is customarily observed in the BEDT–TTF salts. With the Keggin anions the diVerences All the radical salts were obtained on a platinum wire electrode between the BEDT–TTF salts and the BET ones are more by anodic oxidation of the organic donor 1 in a U-shaped pronounced. Thus, while the former donor forms a wide 851 electrocrystallization cell under low constant current (1.2 mA) family of semiconducting salts in which mixed-valence layers in the presence of the tetrabutylammonium (TBA+) salts of of the organic donor alternate with anion layers,5a the latter the polyanions as supporting electrolyte.The TBA+ salts of 2 salts exhibit a dimeric association of fully charged radical were prepared by metathesis from the Na+ salts,13 and recryscations. The lack of mixed valence states in the reported BET tallized from acetone or DMF. The TBA+ salt of 3 was salts may be then attributed to the larger tendency of these prepared by metathesis from the acid (commercial grade), and donors to form [BET·+]2 dimers.The preparation of related recrystallized from acetonitrile. The solvents were not pre- BET salts having higher electron delocalization and, eventually, viously dried. All the crystals were collected, washed with a magnetic component is now being explored.With this aim CH3CN, CH2Cl2 and/or DMF (to remove any portion of we are using Lindqvist and Keggin anions of diVerent charges neutral BET crystals or of the TBA+ salts of the polyanions), and air-dried. Good quality black prismatic crystals of containing magnetic centers. 316 J. Mater. Chem., 1998, 8(2), 313–317BET2[M6O19] (M=W 4, Mo 5) were obtained in DMF, and funding this work.J.R.G-M thanks the Generalitat Valenciana for a pre-doctoral grant. shiny black needle-like crystals of BET4[SiW12O40] 6, were obtained from CH3CN–CH2Cl2 (253). The stoichiometries of 4 and 5 were only determined from the X-ray structure. For 6 References the stoichiometry was determined from elemental analysis which indicated that the correct formula for 6 is 1 E.Coronado and C. J. Go�mez-Garcý�a, Chem. Rev., in press. 2 L. Ouahab, in Polyoxometalates: From Platonic Solids to Anti- BET4[SiW12O40]·CH3CN·2H2O (Found: C, 11.81; H, 0.94; N, Retroviral Activity, ed. M. T. Pope and A. Mu� ller, Kluwer 0.39; S, 16,91%. Calc.: C, 11.92; H, 0.97; N, 0.33; S, 18.18%). Academic, Dordrecht, 1994, p. 245. 3 (a) E.Coronado, J. R. Gala�n Mascaro� s, C. Gime�nez-Saiz and X-Ray crystallography C. J. Go�mez-Garcý�a, in Magnetism: A Supramolecular Function, NATO ASI Series, ed. O. Kahn, Kluwer Academic, Dordrecht, Crystals of the three salts, which are stable in air, were mounted 1996, vol. C484, p. 281; (b) E. Coronado, J. R. Gala�n-Mascaro� s, on an Enraf-Nonius CAD4 diVractometer equipped with a C.Gime�nez-Saiz and C. J. Go�mez-Garcý�a, Synth. Met., 1997, 85, graphite crystal, incident beam monochromator. Preliminary 1647. examination and data collection were performed with Mo-Ka 4 C. Bellito, D. Attanasio, M. Bonamico, V. Fares, P. Imperatori and S. Patrizio, Mater. Res. Soc. Symp. Proc., 1990, 173, 143. radiation. Cell constants and an orientation matrix for data 5 (a) C.J. Go� mez-Garcý�a, C. Gime�nez-Saiz, S. Triki, E. Coronado, collection were obtained from least-squares refinement, using P. Le Magueres, L. Ouahab, L. Ducasse, C. Sourisseau and the setting angles of 25 reflections. Lorentz, polarization and a P. Delhaes, Inorg. Chem., 1995, 4139; (b) J. R. Gala�n-Mascaro� s, semi-empirical absorption correction (y-scan method)14 were C. Gimenez-Saiz, S. Triki, C.J. Go�mez-Garcý�a, E. Coronado and applied to the intensity data. Other important features of the L. Ouahab, Angew. Chem., Int. Ed. Engl., 1995, 34, 1460. crystals are summarized in Table 2 with atomic coordinates and 6 E. Coronado, J. R. Gala�n-Mascaro� s, C. Gimenez-Saiz, C. J. Gomez-Garcý�a and V. N. Laukhin, Adv.Mater., 1996, 8, 801. thermal parameters for 4 and 5 listed in Tables 3 and 4.The X- 7 (a) J. Tarres, N. Santalo, M. Mas, E. Molins, J. Veciana, C. Rovira, ray crystal structures were determined for 4 and 5 (M=Mo, S. Yang, H. Lee, D. O. Cowan. M. L. Doublet and E. Canadell, W), which are isostructural as expected, and were solved by Chem. Mater., 1995, 7, 1558; (b) E. Ribera, J. Tarre�s, V. Laukhin, direct methods and developed with successive full-matrix least- E.Canadell, M. Mas, E. Molins, J. Veciana and C. Rovira, Synth. squares refinements and diVerence Fourier syntheses, which Met., 1997, 86, 2145. showed all the atoms of organic donors and polyanions. In 8 E. Coronado, L. Falvello, J. R. Gala�n-Mascaro� s, C. Gime�nez-Saiz, C. J. Go�mez-Garcý�a, V. Lauhkin, A. Pe�rez-Bený�tez, C. Rovira and contrast, the structure of 6 could not be fully determined and J.Veciana, Adv.Mater., 1997, 9, 984. only the atoms of polyanions and two BET molecules could be 9 C. Rovira, J. Veciana, N. Santalo� , J. Tarre�s, J. Cirujeda, E. Molins, found. This was owing to the presence of disorder aVecting the J. Llorca and E. Espinosa, J. Org. Chem., 1994, 59, 3307. position of the other two BET molecules in the formula, and to 10 P. Guionneau, C. J. Kepert, G. Bravic, D. Chasseau, M. R. Truter, the poor quality of the crystals, which prevented the assigment M. Kurmoo and P. Day, Synth.Met., 1997, 86, 1973. of peaks with Dr <2.53 e A ° -3. Full crystallographic details, 11 B. Torrance, B. A. Scott, B. Walter, F. B. Kaufman and P. E. Seiden, Phys. Rev. B, 1979, 19, 730. excluding structure factors, have been deposited at the 12 S. Triki, L. Ouahab and D. Grandjean, Acta Crystallogr., Sect. C, Cambridge Crystallographic Data Centre (CCDC). See 1991, 47, 645. Information for Authors, J. Mater. Chem., 1998, Issue 1. Any 13 (a) N. H. Hur, W. G. Klemperer and R. C. Wang, Inorg. Synth., request to the CCDC for this material should quote the full 1990, 27, 80; (b)M. Fournier, Inorg. Synth., 1990, 27, 77. literature citation and the reference number 1145/68. 14 A. C. T. North, D. C. Philips and F. S. Mathews, Acta Crystallogr., Sect. A, 1968, 24, 351. We thank the Ministerio de Educacio�n y Cultura (CICYT) and tper 7/06866B; Received 23rd September, 1997 J. Mater. Chem., 1998, 8(2), 313–317 317