Znorg. Chem. 1985, 24, 4307-431 1 Table VII. Secondary Contacts to the Sb(II1) AX4E Polyhedron in SblFld-Anions compound
(TkzSe2j(Sb3Fe14j(SbF6)r (Te2Se4)(Sb3F14)(SbF6)d (Te30% o)@b3Fi4)(SbFdC
face capping
edge bridging
0 3 4
4 2 0
“Reference 21. bReference 22. CThiswork. “Reference 13.
less than the sum of the appropriate van der Waals radii.28 As in all of the homopolyatomic M42+cations all four edges of the cations are bridged by fluorine atoms, and there are also several contacts approximately along the diagonals of the square-planar cations (Figure 1). In (Te2Se2)(Sb3FI4)(SbF6) the edge-bridging contacts are unsymmetrical and involve atoms F(21) and F(41), which are 0.46 and 0.93 8, respectively out of the plane of the truns-Te2Se?+ cation. In addition the contact Te( 1)--F(33) is along the extension of the Te-Te diagonal of the cation [Te(l)’-.Te(l)--F(33) is 176.7 (9)O] with the atom F(33) 0.17 8,out of the plane of the cation. These contacts are ca. 0.75-0.55 8, shorter than the sum of the neutral-atom van der Waals radii. The edges of the averaged cation Te3,0Sel,02+ are symmetrically bridged by the atoms F(13), F(22), F(42), and F(44). These (28) Bondi, A. J . Phys. Chem. 1964,68, 441.
4307
bridging distances vary from 2.85 to 3.40 A and are quite similar in length to the contacts in Te4(SbF6)2.g They do however, lie significantly (0.73-1.54 A) out of the average plane of the cation. The remaining contacts are more irregular (Figure 1). The contacts Te( 1).-F(45), Te(3)-.F( 15), and Te(4)-.F(12) could possibly be regarded as being analogous to the “diagonal” contacts in Te2Se2+. These anionation contacts can be regarded as being nucleophilic and involve the donation of electron density from fluorine atoms into the lowest unoccupied M O s of the cation. The analogous interactions in the homopolyatomic cations M42+(M = S, Se and Te) are discussed more extensively e l ~ e w h e r e . ~ Acknowledgment. We thank the Natural Sciences and Engineering Research Council of Canada for financial support of this work, Dr. J. E. Vekris for preparing the Te-Se alloy, and Dr. G. J. Schrobilgen for valuable assistance with the ”Se N M R measurements. Registry No. trans-(Te2Sez)(Sb3F14)(SbF6), 68791-83-3; (Te,,oSel.o)(Sb3F14)(SbF6), 98587-07-6; Te, 13494-80-9; Se, 7782-49-2; SbF5, 7783-70-2. Supplementary Material Available: A comparison of the geometries of the known Sb3F1canions (Table VI), listings of anisotropic thermal parameters (Table VIII), bond distances and bond angles in the Sb3Fl; and S b F c anions (Table IX), and final structure factor amplitudes (Table X), and drawings of the crystal packing in (TezSez)(Sb3F14)(SbF6) (Figure 5) and (Te3.~el,o)(Sb3F,4)(SbF6) (Figure 6) (51 pages). Ordering information is given on any current masthead page.
Contribution from the Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523
Preparation and Characterization of Silver(1) Teflate Complexes: Bridging OTeF5 Groups in the Solid State and in Solution STEVEN H. STRAUSS,* MARK D. NOIROT, and OREN P. ANDERSON Received January 18, 1985 The preparations of AgOTeF5CH2ClZand [AgOTeF5(C6H5CH3)z]zare reported. The latter compound crystallizes in the monoclinic system, space group P21/c (No. 14). Unit cell parameters are a = 9.363 (2) A, b = 18.109 (4) A, c = 10.514 (2) A, /3 = 112.89 (2)O, and Z = 2. The centrosymmetric dimeric molecules contain planar Ag,02 cores, with two OTeF5 groups bridging two silver atoms. A molecular weight determination demonstrates that the compound is also dimeric in toluene solution. The Ag-0 and Ag-0’ bond distances are 2.396 (3) and 2.368 (3) A, respectively. The Ag-O-Ag’ and 0-Ag-0’ bond angles are 101.4 (1) and 78.6 (1)O, respectively. Structural and spectroscopic data indicate that the silver(1)-oxygen bonds in this compound have a large amount of ionic character. Spectroscopic data indicate that AgOTeFS.CH2Cl2and the literature compound AgOTeF5(CH3CN), also contain bridging OTeF5 groups in the solid state. These data provide the first evidence that the OTeF5 group can bridge two elements in the solid state and in solution. Our structure also demonstrates that teflate is a much stronger ligand than perchlorate in this type of complex. This is the first direct comparison of the ligating ability of teflate to another monovalent oxoanion.
Introduction
Pentafluoroorthotellurate (OTeFY), or teflate, has only recently been used as a ligand for high-valent’ and l o ~ - v a l e n t *transi~~ tion-metal chemistry. This bulkye and electronegative’ pseu(a) Seppelt, K. Chem. Ber. 1975, 108, 1823. (b) Templeton, L. K.; Templeton, D. H.; Bartlett, N.; Seppelt, K. Inorg. Chem. 1976, 15, 2720. (c) Schroder, K.; Sladky, F. Chem. Ber. 1980,113, 1414.. (d) Huppman, P.; Lentz, D.; Seppelt, K. J. Fluorine Chem. 1980, 16, 578. (e) Schroder, K.; Sladky, F. 2.Anorg. Allg. Chem. 1981, 477, 95. (f) Huppman, P.;Labischinski, H.; Lentz, D.; Pritzkow, H.; Seppelt, K. Z. Anorg. Allg. Chem. 1982, 487, 7. (g) Straws, S.H.; Miller, P. K., unpublished data, 1984. (h) Strauss, S . H.; Pawlik, M. J., unpublished data, 1984. Strauss, S . H.; Abney, K. D.; Long, K. M.; Anderson, 0. P. Inorg. Chem. 1984, 23, 1994. Strauss, S.H.; Colsman, M. R.; Manning, M. C., manuscript in preparation. The ionic radius of the teflate anion has been estimated to be 2.3-2.4 A from crystallographicdata for the K+, Rb*, and Cs+ salts’ (cf. I-, 2.12 A6).
dohalide holds the promise of inducing coordinative unsaturation by means of nonbonded interactions with other ligands in a metal complex. In addition, coordinative unsaturation may be realized because of the inability of this bulky, unidentate anion to form extended lattices. To facilitate the synthesis of a wide vareity of metal teflates, we have prepared silver(1) teflate, AgOTeF,, as a halide/OTeF,- metathesis reagent. A material prepared earlier by Sladky et al.839and formulated by them as AgOTeF5(CH3CN), is less useful for generating coordinatively unsaturated complexes because it contains several equivalents of the two-electron donor acetonitrile. ( 5 ) (a) Sladky, F.; Kropshofer, H.; Leitzke, 0. J. Chem. Soc., Chem. Commun. 1973, 134. (b) Kropshofer, H.; Leitzke, 0.;Peringer, P.; Sladky, F. Chem. Ber. 1981, 114, 2644. (6) Ladd, M. F. C. Theor. Chim. Acta 1968, 12, 333. (7) See ref 2 and references therein. (8) Mayer, E.; Sladky, F. Inorg. Chem. 1975, 14, 539. (9) Sladky, F.; Kropshofer, H.; Leitzke, 0.;Peringer, P. J. Inorg. Nucl. Chem., Suppl. 1976, 69.
0020- 166918511324-4307%01.5010 0 1985 American Chemical Society
4308 Inorganic Chemistry, Vol. 24, No. 25, 1985 In this paper we describe the preparation and characterization of AgOTeF5 and its bis(to1uene) adduct. An X-ray structural determination shows that the latter compound is a dimer with two OTeFS groups bridging two silver atoms, producing a centrosymmetric Ag202core. A molecular weight determination shows that this compound is also dimeric in toluene solution. Vibrational spectroscopic data suggest that AgOTeFS and AgOTeFS(CH,CN), also contain bridging teflate groups. Despite the large amount of main-group OTeFs chemistry studied during the past 20 years,I0 this paper reports the first evidence that teflate can bridge two elements in the solid state and in solution. While this work was in progress, we learned that Au(OTeF& also contains bridging teflate groups in the solid state.” Experimental Section Reagents and Solvents. Toluene, benzene-d,, and hexane were distilled from sodium. Dichloromethane, dichloromethane-d2, and acetonitrile were distilled from CaH2. These solvents were stored under vacuum or under a purified dinitrogen atmosphere prior to use. Silver(1) fluoride (Cerac) and AgCN (Aldrich) were used as received. Teflic acid,I2 HOTeF5, was prepared by literature procedure^.^^,'^ In the following preparations and physical measurements, all operations were carried out with rigorous exclusion of dioxygen and water. Schlenk, glovebox, and high-vacuum techniques were employed, with purified dinitrogen used when an inert atmosphere was required. Physical Measurements. Samples for I9F N M R spectroscopy were dichloromethane or toluene solutions with 1% CFCI, added. Chemical shifts (6 scale) are relative to the CFCI, internal standard. Spectra were recorded at room temperature on a Bruker SY-200 spectrometer operating at 188.31 MHz. All I9F N M R spectra were AB4X patterns upfield of CFCI, (X = Iz5Te, 7.0% natural abundance, I = Samples for IH N M R spectroscopy were dichloromethane-d2 or benzene-d6 solutions with 1% Me4% added. Spectra were recorded on a Bruker SY-270 spectrometer operating at 270.13 MHz. Samples for IR spectroscopy were mulls (Nujol or Fluorolube, KBr windows) or solutions (dichloromethane, toluene, or acetonitrile, 0.2 mm path length IR-tran cells). Spectra were recorded on a Perkin-Elmer 983 spectrometer calibrated with polystyrene. Band positions are 11 cm-l. Samples for Raman spectroscopy were crystalline or microcrystalline solids loaded into glass capillaries. Spectra were recorded with a Spex Ramalog 5 spectrophotometer calibrated with standard compounds. The 514.5-nm line of an argon ion laser was used to excite the samples. The molecular weight of (AgOTeF5(C6H5CH3)2]2 in toluene solution was measured with use of an isopiestic molecular-weight a p p a r a t ~ s . ’ ~ Tris(acetylacetonato)iron(III) (recrystallized from benzene) was used as the molecular weight standard. Preparation of Compounds. AgOTeF5.CH2Cl2.Anhydrous AgF (3.8 g, 30 mmol) and dichloromethane (30 mL) were charged into a stainless steel vessel equipped with a stainless steel valve and a Kel-F valve seat. Teflic acid (6.7 g, 28 mmol) was vacuum transferred into the reaction vessel at -196 OC. The reaction mixture was agitated for 3 h at room temperature. Removal of all volatiles under vacuum left a free-flowing gray powder. This was immediately dissolved in a minimum of dichloromethane and filtered, leaving a colorless solution. Flash evaporation of the solvent left a white powder, formulated (see below) as AgOTeF5CH2C12(>85% yield based on HOTeF,). I9F N M R (dichloromethane): 6, -30.0, bB -41.2, J A B = 180 Hz, JAX = 3041 Hi!, JBX = 3626 Hz. [AgOTeF5(C6H5CH3)2]2. The above procedure was repeated with toluene in place of dichloromethane. A white powder, [AgOTeF5(C6H,CH,),],, can be isolated in 10-g batches (>90% yield based on HOTeF5). Crystals suitable for diffraction were grown by slowly cooling a saturated toluene solution of this compound. 19FN M R (toluene): 6A -26.1, 68 -37.9, J A B = 180 Hz, J A x = 3030 Hz, J B x = 3659 Hz.
(IO) (a) Seppelt, K. Acc. Chem. Res. 1979, 12, 211. (b) Engelbrecht, A.; Sladky, F.Adu. Inorg. Chem. Rodiochem. 1981,24, 189. (c) Seppelt, K. Angew. Chem., In?. Ed. EngI. 1982, 21, 877. (d) Strauss, S. H.; Abney, K. D.Inorg. Chem. 1984, 23, 515. (1 1) Seppelt, K., personal communication, 1984. (12) We suggest the abbreviations teflate and teflic acid in place of the correct nomenclature pentafluoroorthotellurate and pentafluoroorthotelluric acid, respectively. The latter compound is the parent from which all teflates are prepared.’O (13) Seppelt, K.; Nothe, D. Inorg. Chem. 1973, 12, 2727. (14) Strauss, S. H.; Abney, K. D.; Anderson, 0. P., manuscript in preparation. ( 1 5 ) Shriver, D. F. “The Manipulation of Air-Sensitive Compounds”; McGraw-Hill: New York, 1969; p 73.
Strauss et al. Table I. Experimental Parameters for the X-ray Diffraction Study mol formula mol wt space group unit cell dimens
[A~OT~FS(C~HSCH 2 &I 1061.49 g/mol P2ilC
unit cell volume
9.363 (2) 8, 18.109 (4) A 10.514 (2) 8, 112.89 (2)’ 1642.3 A3
2
L
calcd density cryst dimens data collecn temp radiation monochromator abs coeff 20 range unique reflcns obsd reflcns scan type scan speed data/parameter ratio R Rw
2.15 g cm-, 0.35 mm X 0.30 mm X 0.45 mm -130 OC Mo K a (A = 0.71073 8,) graphite 30.38 cm-I 3.5-55 O 3798 for h > 0, k > 0, AI 3242 with I > 2.5a(I) 0-20 variable, 2-30° min-’ 15.8 0.027 0.030 1.44 4.3 x 10-4 1.11
a
b c
P
GOF
g
slope of normal probability plot
[AgOTeF5(CH,CN),I2.The preparation of this compound follows a literature p r o c e d ~ r e . ~Silver(1) .~ cyanide (1.1 g, 8.3 mmol) and acetonitrile (30 mL) were charged into a Schlenk flask. Very little of the AgCN dissolved. Teflic acid (2.0 g, 8.3 mmol) was vacuum transferred into the flask at -196 OC. The reaction mixture was stirred at room temperature for several hours, affording a colorless solution. Removal of all volatiles under vacuum left a sticky white solid. Crystallographic Study. A colorless prism of [AgOTeF5(C6H5CH3)2]2 was centered on a Nicolet R3m diffractometer. The setting angles for 25 reflections (2O(av) = 17.60O) allowed least-squares calculationi6 of the cell constants. Relevant experimental parameters and results are listed in Table I. The intensities of all reflections were measured by using 0-20 scans, with a scan range of [2.0 1.0(20K,, - 2OKa2)I0,where the background measurement was taken for half the total scan time at the scan extremes. The intensities of control reflections (400, 060,006) monitored every 97 reflections showed no significant trend during the course of the data collection. An empirical absorption correction, based on intensity profiles for 15 reflections over a range of setting angles (3.) for the diffraction vector, was applied to the observed data. The applied transmission factors ranged 1 9 % about the mean value. Lorentz and polarization corrections were carried out on the unique observed reflections used in the leastsquares refinement. The space group was uniquely determined to be P2,/c (No. 14) by systematic absences for hOl ( I = 2n 1) and OkO ( k = 2n l),” The tellurium and silver atoms were located by Patterson methods, and all other non-hydrogen atoms were located in difference Fourier maps, in which phases were determined by the previously located atoms. Subsequent refinement involved anisotropic thermal parameters for all non-hydrogen atoms. Neutral-atom scattering factors (including anomalous scattering) were taken from ref 18. Hydrogen atoms were included in calculated positions 0.96 8, from carbon atoms, with isotropic thermal parameters 1.2 times the equivalent isotropic thermal parameter for the carbon atoms to which they were attached. The weighted least-squares refinement (weights calculated as (a2(Fj ?F,2)-’) converged, with the average shift/esd
