The article discusses the low-temperature phase of bis(tetrabutylammonium) octa-µ3-chlorido-hexachlorido-octahedro-hexa-tungstate, which undergoes a reversible phase transition at 268 K. The unit cells of the room- and low-temperature polymorphs of this compound are found to be closely related. The hydrocarbon chain of one of the tetrabutylammonium cations is found to be disordered at both 150 and 200 K

Brown, Chris M

Gallucci, Judith C

Johnston, Dean H

Yu, Andrew S

English

Otterbein University

Otterbein University Digital Commons @ Otterbein Chemistry Faculty Scholarship Chemistry 9-24-2010 A low-temperature phase of bis(tetrabutylammonium) octa-l3-chloridohexachlorido- octahedro-hexatungstate Dean H. Johnston Otterbein University Chris M. Brown Otterbein University Andrew S. Yu Otterbein University Judith C. Gallucci Ohio State University - Main Campus Follow this and additional works at: https://digitalcommons.otterbein.edu/chem_fac  Part of the Chemistry Commons Repository Citation Johnston, Dean H.; Brown, Chris M.; Yu, Andrew S.; and Gallucci, Judith C., "A low-temperature phase of bis(tetrabutylammonium) octa-l3-chloridohexachlorido- octahedro-hexatungstate" (2010). Chemistry Faculty Scholarship. 1. https://digitalcommons.otterbein.edu/chem_fac/1 This Article is brought to you for free and open access by the Chemistry at Digital Commons @ Otterbein. It has been accepted for inclusion in Chemistry Faculty Scholarship by an authorized administrator of Digital Commons @ Otterbein. For more information, please contact digitalcommons07@otterbein.edu. A low-temperature phase of bis(tetra-butylammonium) octa-l3-chlorido-hexachlorido-octahedro-hexa-tungstateDean H. Johnston,a* Chris M. Brown,a Andrew S. Yua andJudith C. GalluccibaDepartment of Chemistry, Otterbein University, Westerville, OH 43081, USA, andbDepartment of Chemistry, The Ohio State University, 100 W. 18th Avenue,Columbus, Ohio 43210, USACorrespondence e-mail: djohnston@otterbein.eduReceived 12 February 2010Accepted 15 September 2010Online 24 September 2010The title compound, (C16H36N)2[W6Cl14], undergoes a rever-sible phase transition at 268 (1) K. The structure at 150 and200 K has monoclinic (P21/c) symmetry. Both crystallographi-cally independent tungsten chloride cluster anions sit oncrystallographic inversion centers [symmetry codes: (x,y + 1, z) and (x + 1, y + 2, z)]. Two previous studiesat room temperature describe the structure in the space groupP21/n with a unit-cell volume approximately half the size ofthe low-temperature unit cell [Zietlow, Schaefer et al. (1986).Inorg. Chem. 25, 2195–2198; Venkataraman et al. (1999).Inorg. Chem. 38, 828–830]. The unit cells of the room- and low-temperature polymorphs are closely related. The hydrocarbonchain of one of the tetrabutylammonium cations is disorderedat both 150 and 200 K.CommentThe lower halides of tungsten, including tungsten(II) chloride,have been known for over 100 years (Kepert & Vrieze, 1967;Prokopuk & Shriver, 1999) and numerous methods for theirsynthesis have been developed (Hogue & McCarley, 1970;Dorman & McCarley, 1974; Kolesnichenko & Messerle, 1998;Stro¨bele et al., 2009). The structure of the [(W6Cl8)Cl6]2anion was first determined by Zietlow, Schaefer et al. (1986) atroom temperature. A subsequent structure determination ofthe same form was published by Venkataraman et al. (1999).The tungsten(II) halide clusters have been intensely studiedbecause of their fascinating photochemical and electro-chemical properties (Maverick et al., 1983; Nocera & Gray,1984; Zietlow et al., 1985; Zietlow, Nocera et al., 1986; Jacksonet al., 1990; Mussell & Nocera, 1990; Arratia-Pe´rez &Herna´ndez-Acevedo, 1997; Gray, 2009).At low temperature, the two independent [(W6Cl8)Cl6]2cluster units (Fig. 1) sit on crystallographic inversion centersand have bond lengths and bond angles comparable to thoseof previously determined structures (Zietlow, Schaefer et al.,1986; Venkataraman et al., 1999). One hydrocarbon chain ofone of the two tetrabutylammonium cations (Fig. 1) is disor-dered and was modeled with two sites each for three differentC atoms. A packing diagram is shown in Fig. 2.There is a close relationship between the unit cell of theherein reported low-temperature (150 and 200 K) structuresand that of the previously determined room-temperaturestructures. The cell dimensions of the room-temperature unitcell are a = 18.512 A˚, b = 11.661 A˚, c = 12.789 A˚,  = 90,  =metal-organic compoundsActa Cryst. (2010). C66, m303–m306 doi:10.1107/S0108270110037017 # 2010 International Union of Crystallography m303Acta Crystallographica Section CCrystal StructureCommunicationsISSN 0108-2701Figure 1Displacement ellipsoid (50% probability level) drawing of the twoindividual tungsten cluster anions and the two tetrabutylammoniumcations in the asymmetric unit for the 150 K structure, showing the atom-numbering scheme. [Symmetry codes: (i) x, y + 1, z; (ii) x + 1,y + 2, z.]90.17 and  = 90 (Zietlow, Schaefer et al., 1986), while at150 K the unit cell is a = 22.3152 (2) A˚, b = 11.7220 (1) A˚, c =22.2786 (1) A˚,  = 90,  = 112.451 (1) and  = 90. Appli-cation of the transformation matrix [12 012/0 1 0/12 012] to the unitcell of the low-temperature form produces the following unitcell, which is approximately identical to the room-temperaturecell: a = 18.534 A˚, b = 11.722 A˚, c = 12.395 A˚,  = 90,  =89.90 and  = 90. An overlay of the two unit cells is shown inFig. 3 (r.m.s. overlay = 0.177 A˚ for 122 non-H atoms). Thistransformation is possible because the low-temperature unitcell shows higher metric symmetry, namely the a and c axes areapproximately equal. This allows for a pseudo-orthorhombicC-centered cell to be generated using the transformationmatrix [1 0 1/1 0 1/0 1 0]. The room-temperature cell can begenerated from this pseudo-orthorhombic cell by dividing thea and b axes by two, followed by a rearrangement of the axes.The relationship between the unit cells was not noticed untilafter the data collection when the crystal had already beenremoved from the diffractometer. At a later point, a newcrystal of the same sample was mounted on the diffractometerat 150 K and a preliminary unit-cell determination agreed withthe cell at 200 K from the data-collection crystal. Then thetemperature was raised to 200 K and the unit cell was deter-mined again and it was essentially the same cell. Finally, thetemperature was increased to room temperature (293 K) andthe unit cell changed to become the room-temperature cellreported in the literature.A further study was undertaken to determine the phase-transition temperature. A new crystal of the title compoundwas mounted on a Rigaku SCXmini small-molecule X-raycrystallography system equipped with a Rigaku TEC-50 low-temperature device. The temperature at the sample wasverified using a calibrated thermocouple. The previouslydetermined unit cells were confirmed at room temperatureand at 223 K. Repeated indexing of the crystal at successivelyhigher temperatures demonstrated that the crystal undergoesa reversible phase transition between 267 and 269 K. Thisresult was reproduced using a different crystal of the samecompound.A search of the Cambridge Structural Database (CSD;Version 5.31; Allen, 2002) revealed that the smaller P21/n unitcell observed for the room-temperature structure is commonto a range of tetrabutylammonium salts of metal–halide andmetal–chalcogenide cluster dianions. Examples includemolybdenum halide clusters (Preetz et al., 1992, 1994; Kirakciet al., 2005), molybdenum chalcogenide/halide clusters (Ebi-hara et al., 1992), tungsten halide clusters (Zietlow, Schaefer etal., 1986; Venkataraman et al., 1999) and rhenium chalco-genide/halide clusters (Gabriel et al., 1993; Uriel et al., 1995,1996, 2001). Only two examples were found with the samelarger P21/c unit cell as the low-temperature phase of the titlecompound: the [(Os2Re4Se8)Cl6]2 dianion structure deter-mined at 153 K by Tulsky & Long (2001) and the [(Re6Se5-Cl2N-TMS)Cl6]2 (TMS is trimethylsilyl) anion structuredetermined at room temperature by Uriel et al. (1996).Among these examples, only one structure was found thatpotentially undergoes a similar phase change. The [(Re6Se6-Cl2)Cl6]2 dianion structure was determined in a tetragonalsetting (space group I4/mmm; Yaghi et al., 1992) at 198 K,while two other structure determinations of the samecompound at room temperature (Uriel et al., 1995, 2001)display the P21/n unit cell found for the room-temperaturestructure of the title compound and many other structures.The analogous [(Mo6Br8)Br6]2 dianion structure, however,has been determined at 100 K and room temperature (Kirakciet al., 2005) and in both cases the P21/n unit cell was found.metal-organic compoundsm304 Johnston et al.  Two polymorphs of (C16H36N)2[W6Cl14] Acta Cryst. (2010). C66, m303–m306Figure 3Overlay diagram showing the packing similarity between the current150 K structure (blue in the electronic version of the paper) and thepreviously determined room-temperature structure (green), togetherwith both unit cells, as well as the unit cell derived from the low-temperature cell by application of the transformation matrix [12 012/0 1 0/12 012]. H atoms and atoms of the minor component of the disorder werenot included in the overlay analysis and have been omitted from thisfigure.Figure 2Displacement ellipsoid (50% probability level) drawing of the contents ofthe unit cell along the b axis for the 150 K structure. H atoms and theminor component of the disorder have been omitted for clarity.ExperimentalThe tungsten(II) chloride cluster was prepared via the reduction oftungsten(VI) chloride with bismuth according to published proce-dures (Kolesnichenko & Messerle, 1998). The hydronium salt wasconverted to the tetrabutylammonium salt by metathesis with tetra-butylammonium chloride in ethanol solution. The crude product wasrecrystallized by slow evaporation from an acetone solution. Crystalssuitable for X-ray analysis were grown by slow diffusion of diethylether into a solution of (I) in dichloromethane.Compound (I) at 150 KCrystal data(C16H36N)2[W6Cl14]Mr = 2084.32Monoclinic, P21=ca = 22.3152 (2) A˚b = 11.7220 (1) A˚c = 22.2786 (1) A˚ = 112.415 (1)V = 5387.31 (7) A˚3Z = 4Mo K radiation = 13.48 mm1T = 150 K0.31  0.27  0.23 mmData collectionNonius KappaCCD diffractometerAbsorption correction: multi-scan(SADABS; Bruker, 2008)Tmin = 0.484, Tmax = 0.746137050 measured reflections12352 independent reflections9499 reflections with I > 2(I)Rint = 0.086RefinementR[F 2 > 2(F 2)] = 0.031wR(F 2) = 0.054S = 1.0712352 reflections515 parameters148 restraintsH-atom parameters constrainedmax = 1.20 e A˚3min = 1.69 e A˚3Compound (I) at 200 KCrystal data(C16H36N)2[W6Cl14]Mr = 2084.32Monoclinic, P21=ca = 22.3689 (2) A˚b = 11.7596 (1) A˚c = 22.3108 (2) A˚ = 112.320 (1)V = 5429.13 (8) A˚3Z = 4Mo K radiation = 13.38 mm1T = 200 K0.27  0.19  0.19 mmData collectionNonius KappaCCD diffractometerAbsorption correction: multi-scan(SCALEPACK; Otwinowski &Minor, 1997)Tmin = 0.055, Tmax = 0.079101212 measured reflections12422 independent reflections9227 reflections with I > 2(I)Rint = 0.063RefinementR[F 2 > 2(F 2)] = 0.031wR(F 2) = 0.064S = 1.0312422 reflections515 parameters148 restraintsH-atom parameters constrainedmax = 2.36 e A˚3min = 2.11 e A˚3The asymmetric unit of (I) at both temperatures consists of twotetrabutylammonium cations and two half-octahedra of the[W6Cl14]2 cluster anion, with each octahedron containing a crystal-lographic inversion center.Not surprisingly, the two low-temperature structures, determinedat 150 and 200 K, are essentially identical. In both cases, one of thehydrocarbon chains was found to be disordered and was modeledwith two sites for each of the last three C atoms of the n-butyl chain.The occupancies of the two disorder components were refined freelyand converged at 0.555 (11) for the 200 K structure and at 0.616 (10)for the 150 K structure; the sum of the site-occupancy factors for eachdisorder was constrained to unity. The major component of thedisordered chain contains atoms C14, C15 and C16, while the minorcomponent consists of atoms C14A, C15A and C16A.Similarity restraints on 1–2 and 1–3 distances (standard uncer-tainties = 0.02 and 0.04 A˚, respectively) were used to geometricallyrelate the two components of the disordered n-butyl chain to oneanother and also to the remaining three butyl chains of the firsttetrabutylammonium ion. In addition, similarity restraints ondisplacement parameters (standard uncertainty = 0.04 A˚2, or 0.08 A˚2for terminal atoms), as well as rigid-bond restraints for anisotropicdisplacement parameters (standard uncertainty = 0.01 A˚2), wereapplied to all disordered atoms as well as to C13.metal-organic compoundsActa Cryst. (2010). C66, m303–m306 Johnston et al.  Two polymorphs of (C16H36N)2[W6Cl14] m305Table 1Selected bond lengths (A˚) for (I) at 150 K.W1—W2 2.6048 (3)W1—W2i 2.6212 (3)W1—W3 2.6163 (3)W1—W3i 2.6091 (3)W2—W3 2.6120 (3)W2—W3i 2.6207 (3)W1—Cl1 2.4181 (13)W2—Cl2 2.4292 (13)W3—Cl3 2.4310 (13)W1—Cl4 2.5037 (12)W1—Cl5 2.5028 (13)W1—Cl6 2.4968 (13)W1—Cl7 2.4934 (12)W2—Cl4 2.5044 (13)W2—Cl5 2.4927 (12)W2—Cl6i 2.4919 (13)W2—Cl7i 2.4987 (12)W3—Cl4 2.4977 (13)W3—Cl5i 2.4856 (12)W3—Cl6 2.5090 (13)W3—Cl7i 2.5055 (13)W4—W5 2.6092 (3)W4—W5ii 2.6127 (3)W4—W6 2.6133 (3)W4—W6ii 2.6143 (3)W5—W6 2.6152 (3)W5—W6ii 2.6071 (3)W4—Cl8 2.4243 (14)W5—Cl9 2.4187 (13)W6—Cl10 2.4328 (13)W4—Cl11 2.4941 (13)W4—Cl12 2.4926 (13)W4—Cl13 2.5034 (12)W4—Cl14 2.4979 (13)W5—Cl11ii 2.4969 (14)W5—Cl12 2.5044 (14)W5—Cl13ii 2.4954 (13)W5—Cl14 2.4974 (13)W6—Cl11ii 2.4972 (13)W6—Cl12ii 2.4978 (13)W6—Cl13 2.5062 (14)W6—Cl14 2.4844 (13)Symmetry codes: (i) x;yþ 1;z; (ii) xþ 1;yþ 2;z.Table 2Selected bond lengths (A˚) for (I) at 200 K.W1—W2 2.6056 (3)W1—W2i 2.6228 (3)W1—W3 2.6191 (3)W1—W3i 2.6101 (3)W2—W3 2.6131 (3)W2—W3i 2.6239 (3)W1—Cl1 2.4177 (14)W2—Cl2 2.4289 (14)W3—Cl3 2.4285 (14)W1—Cl4 2.5012 (14)W1—Cl5 2.4961 (14)W1—Cl6 2.4980 (15)W1—Cl7 2.4962 (14)W2—Cl4 2.5067 (14)W2—Cl5 2.4905 (14)W2—Cl6i 2.4864 (14)W2—Cl7i 2.4967 (13)W3—Cl4 2.4965 (13)W3—Cl5i 2.4888 (13)W3—Cl6 2.5088 (15)W3—Cl7i 2.5020 (14)W4—W5 2.6113 (3)W4—W5ii 2.6157 (3)W4—W6 2.6169 (3)W4—W6ii 2.6170 (3)W5—W6 2.6186 (3)W5—W6ii 2.6096 (3)W4—Cl8 2.4187 (16)W5—Cl9 2.4173 (14)W6—Cl10 2.4297 (15)W4—Cl11 2.4928 (14)W4—Cl12 2.4903 (14)W4—Cl13 2.5029 (14)W4—Cl14 2.4965 (14)W5—Cl11ii 2.5003 (16)W5—Cl12 2.5033 (15)W5—Cl13ii 2.4932 (14)W5—Cl14 2.4967 (14)W6—Cl11ii 2.4964 (15)W6—Cl12ii 2.4936 (13)W6—Cl13 2.5046 (14)W6—Cl14 2.4836 (13)Symmetry codes: (i) x;yþ 1;z; (ii) xþ 1;yþ 2;z.The top four peaks in the final difference electron-density maprange from 1.09 to 1.20 e A˚3 (150 K data) and from 1.62 to2.35 e A˚3 (200 K data). All of these peaks are located within 1.5 A˚of a W atom and are presumably Fourier truncation artifacts due tothe presence of multiple heavy atoms.For both compounds, data collection: COLLECT (Nonius, 2000);cell refinement: SCALEPACK (Otwinowski & Minor, 1997); datareduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK;program(s) used to solve structure: SHELXS97 (Sheldrick, 2008);program(s) used to refine structure: SHELXL97 (Sheldrick, 2008);molecular graphics: ORTEP-3 for Windows (Farrugia, 1997),Mercury (Macrae et al., 2008) and POV-RAY (Cason, 2004); softwareused to prepare material for publication: WinGX (Farrugia, 1999).This work was supported in part by the National ScienceFoundation through grant No. CHE-0532510. 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A low-temperature phase of bis(tetrabutylammonium) octa-l3-chloridohexachlorido- octahedro-hexatungstate

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A low-temperature phase of bis(tetrabutylammonium) octa-l3-chloridohexachlorido- octahedro-hexatungstate

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