Inorg. Chem. 1989, 28, 1847-1853 lattice breakup from grinding, thermal stress, and ambient temperature exposure a t the end of the data collection procedure. The magnetic susceptibility data for form 1 and for the unsolvated /3 phase are displayed graphically in Figure 7. The plotted data are expressed in terms of the magnetic moment per dimer and the room-temprature moments (2.46 and 2.55 pB, respectively) are seen to have values close to the spin-only value of 2.45 F~ (the square root of the sum of the squares of individual S = '/* moments of 1.73 pB). These values, and those of all the higher temperature points, are, of course, quite sensitive to the value of the diamagnetic correction used: -898 and -806 X 10" cgsu/mol of dimer, respectively, for form 1 and the /3 phase. These values are based on Pascal's constantsz9 and do not include the constitutive correction for T P P suggested by Eaton and Eaton30 because doing so leads to unrealistically high moments (-2.8 pB). It is unknown what the constitutive correction for the TPP' radical cation should be, but our current work suggests it may be lower than that of T P P itself. The marked decrease in magnetic moments as a function of decreasing temperature seen in Figure 7 reveals antiferromagnetic coupling in both systems. It is qualitatively evident that spin coupling is stronger in form 1 than in the /3 phase. A quantitative treatment leads to the theoretical fits displayed in the same figure. Fitting parameters are given in the figure caption. The derived values of the isotropic exchange coupling parameter J (in terms of the -2J spin Hamiltonian) are -54 and -1 5 cm-' for form 1 and the /3 phase, respectively. From our experience with the theoretical fitting variables, the uncertainty of the precise diamagnetic correction, and the sample aging difficulties with form 1, we estimate these values are reliable to within about 10%. Particularly because of the aging problem with the dichloromethane solvate, the 1-4 value for form 1 should be considered a lower limit. For the purposes of the present study, the qualitatively conclusion is probably the most important one. Antiferromagnetic coupling is significantly stronger in form 1 than Boudreaux, E. A,; Mulay, L. N. Theory and Applications of Molecular Paramagnetism; Wiley: New York, 1976. Eaton, S. S.;Eaton, G. R. Inorg. Chem. 1980, 19, 1096-1098.
1847
in the /3 phase, and this correlates with the relative extent of the dimer interactions seen in the crystal structures. Table VI lists the dimensional criteria discussed earlier for describing the extent of dimer interaction. Although it is too early to judge which is the most important for magnetic coupling, it seems likely that both the interplanar separation and the degree of lateral overlap are critical. Conclusions. The apparently quite strong driving force toward pairwise association of metallotetraphenylporphyrin n-cationradical species is further demonstrated in these studies. Dimer formation has significant effects on the molecular structure, leading to an unusual saddle-shaped core conformation. Solid-state dimer formation also leads to antiferromagnetic coupling between the ring radicals and the extent of the coupling appears to be quite sensitive to the extent of porphyrin core overlap. Since spin coupling is insufficient to produce diamagnetism a t room temperature, the present work supports the partitioning of intra- and intermolecular spin coupling effects previously made in iron(II1) and copper(I1) porphyrin radicah3v4 Acknowledgment. W e thank Drs. R. H. Blessing and G . DeTitta of the Medical Foundation of Buffalo for providing us the Fortran code of the profile analysis software and Dr. P. D. W . Boyd of the University of Auckland, New Zealand, for magnetic susceptibility fitting programs. W e thank Ted Brennan for work on the structure of [Zn(TPP')(OHZ)]C1O4. W e gratefully acknowledge support of this research by the National Institutes of Health (Grants GM-38401 to W.R.S. and GM-23851 to C.A.R). Registry No. [Zn(TPP')(OC103)].2CH2Clz, 119946-95-1. Supplementary Material Available: Figure S1 (an edge-on view of the dimer of form 2), Figures S2 and S3 (overlap diagrams of the porphyrin core pairs (including phenyl rings)), Figures S4 and S5 (cell-packing diagrams), Tables SI and SI1 (magnetic susceptibility data for form 1 and the p phase, respectively), Table SI11 (complete crystallographic details), and Tables SIV and SV (thermal parameters for the atoms of [Zn(TPP')(OC103)]of forms 1 and 2, respectively) (1 1 pages); listings of observed and calculated structure factor amplitudes (XIO) for the two structures (42 pages). Ordering information is given on any current masthead page.
Contribution from Chemistry Department A, Technical University of Denmark, DK-2800 Lyngby, Denmark, Institute of Chemical Engineering and High Temperature Processes, University of Patras, Gr-26110 Patras, Greece, and Chemistry Department B, Technical University of Denmark, DK-2800 Lyngby, Denmark
Crystal Structure and Infrared and Raman Spectra of K4(V0)3(S04)5 R. F e h r m a n n , l a S . Boghosian,lb,c G. N. P a p a t h e o d o r o u , l b * cK. N i e l s e n , l d R. W. Berg,*-la and N. J. B j e r r u m l a Received June 17, 1988 Blue crystals of K,(VO)3(S04)5suitable for X-ray structure determination have been obtained from solutions of Vz05in molten K2S20,under a SO2/Nzgas mixture. Lowering the temperature from the range 470-450 OC to the range 440-420 OC causes small crystals to precipitate after several hours. The compound crystallizes in the monoclinic space group P2,/n (No. 14) with a = 8.746 (2) A, b = 16.142 (2) A, c = 14.416 (2) A, and (3 = 106.81 (1)' at 18 O C and Z = 4. It contains three different distorted V 0 6 octahedra and five distorted SO4 tetrahedra. The central vanadium atoms have a short bond to one oxide ion, four longer bonds to the oxygens of four sulfate groups, and an especially long axial bond to a fifth SO:-. The vanadium environment is similar to what is found for other vanadyl compounds. The structure has five different sulfate groups, with three of the four sulfate oxygens bridging the vanadiums in a complicated packing pattern. Principal component analyses were performed to examine structure correlations among different sulfate and V 0 6 groups. Infrared and Raman spectra of the compound have been recorded and interpreted.
Introduction The chemistry of the molten V,O5-KHSO4-KZSzO7 system in contact with S O ~ / O ~ / S O ~ /isNbeing , investigated d u e to its importance as a catalyst for the production of sulfuric acid. The ( I ) (a) Chemistry Department A, Technical University of Denmark. (b) University of Patras. (c) Visiting Scientist at the Technical University of Denmark in 1985. (d) Chemistry Department B, Technical University of Denmark.
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investigations so far include a studyZ of the pure solvent system KHSO4-KzSzO7 and the V~05-KzSz07-KzS04 system dilute in vanadium3 and studies4+ of this system at 4OC-500 OC, including (2) Fehrmann, R.;Hansen, N. H.; Bjerrum, N. J. Inorg. Chem. 1983.22, 4009. ( 3 ) Hansen, N.H.; Fehrmann, R.; Bjerrum, N. J. Inorg. Chem. 1982, 21, 744. (4) Fehrmann, R.;Gaune-Escard, M.; Bjerrum, N. J. Inorg. Chem. 1986, 25, 1132.
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1848 Inorganic Chemistry, Vol. 28, No. 10, 1989 melts of the molar ratio range K/V = 2-5, corresponding to the composition of the commercial catalyst. In the VzOS-K2S20, system, vanadium(V) a t small mole fractions, Xv,05, is most probably present as the monomeric oxo sulfato complexes V 0 2 SO4-and V02S04S2073-,whereas the dimeric complex (V02),(S04)2Sz0,4- and polymeric complexes, formulated a s (V02S04),"-, seem to be formed a t higher mole fractions. The compounds K3VO2SO4S2O7,K4(V02)2(S04)zS207. and K V 0 2 S 0 4 have been isolated from the melts.' The formation of complexes in the molten V205-K2S20,system in contact with an SO2 gas atmosphere has been investigated to a much lesser extent. So far, the only paper concerning the complex formation of V(IV) in molten K2S2O7 (at 430 "C) claims* a doubtful existence of the species V O S 0 4 and VO(S04),4-. The investigations was apparently based on electrochemical measurements on K2S2O7 melts to which "wet" chemicals like VOSO4.3.5H2Owere added (changing the solvent to K H S 0 4 due to the reaction K2S2O7 HzO 2 K H S 0 4 ) . Furthermore, the partial pressure of SO2apparently was not controlled, thus leading to an unknown conversion of V(1V) to V(V). For a catalyst under operational conditions, it has been shown by ESR measurements9 that V(1V) species are present both in the solid state and in solution, most probably as the (solvated) vanadyl ion, V 0 2 + . T h e progressive deactivation of the catalyst a t temperatures below -440 "C seems to be related to precipitation of a vanadium(1V) compound. The compound seems to be formedi0 a t the expense of the solute V(IV) species in the catalyst at decreasing temperatures below -480 "C, thus depleting the melt of active vanadium species. Although solid compounds formed in the molten V2z5-K2S2O7 system at catalyst operation conditions were examined, no V(IV) compound has been isolated or identified from the working catalyst. However, melts with the molar ratio K/V = 1 and 6 were treated with a gas stream of 7.5% SOz (30% of SO2 converted to SO3), 1 1 % 02,and 81.5% N2 a t 420 "C. From this melt a compound, containing vanadium in the +IV oxidation state only, was observed having the composition K20-V204.3S03. T h e IR spectrum in KBr and the X-ray powder pattern resemble similar data for the stoichiometrically analogue compound K2SO4.2VOSO4 obtainedi2 by calcination of K2S04 and V O S 0 4 . Very recentlyI3 we reported the structure of a V(II1) compound, KV(S04),, isolated from the molten V,Os (or VZO4)-KHSO4S02(g) system by slow stepwise decrease of the temperature from 450 to 250 "C. This gave evidence for a possible formation of vanadium compounds of oxidation states lower than +V and +IV in melts analogous to the catalyst. The present paper describes the stoichiometry and structure of a new V(IV) compound, K4( V 0 ) 3 ( S 0 4 ) 5 ,which might be important to understanding the deactivation of the sulfuric acid catalyst.
+
F e h r m a n n et al.
lFD" i l
-+
Experimental Section The equipment included a gas-mixing unit that was able to produce a continuous flow of any desired S02/02/S03/N2 ratio. Details of the (5) Hatem, G.; Fehrmann, R.; Gaune-Escard, M.; Bjerrum, N.J. J . Phys. Chem. 1987, 91, 195. (6) Hatem, G.; Fehrmann, R.; Gaune-Escard, M.; Bjerrum, N. J. To be
submitted for publication. Glazyrin, M. P.; Krasil'nikov, V. N.; Ivakin, A. A. Russ. J . Inorg. Chem. (Engl. Transl.) 1980, 25, 1843; 1982, 27, 1740. (8) Durand, A.; Picard, G.; Vedel, J . J . Electroanal, Chem. Interfacial Electrochem. 1981, 127, 169. (9) Boreskov, G. K.; Davydova, L. P.; Mastikhin, V. M.; Polyakova, G. M. Dokl. A k a d . Nauk SSSR 1966, 171,648;Dokl. Chem. (Engl. Transl.) 1966, 171, 760. (IO) Mastikhin, V. M.; Polyakova, G. M.; Zyulkovskii, Y.; Boreskov, G. K. (7)
Kiner. Katal. 1970, 11, 1463; Kinet. Catal. (Engl. Transl.) 1970, 11, 1219
Bazarova, Z. G.; Boreskov, G. K.; Ivanov, A. A,; Karakchiev, L. G.; Kacohkina, 1.D. Kinet. Katal. 1971, 12, 948; Kiner. Catal. (Engl. Transl.) 1971, 12, 845.
Ezhkova, Z. I.; Zaitsev, B. E.; Konysheva, L. I.; Matveevicheva, V . A,; Nekhorosheva. N.I.; Polotnyuk, 0 . - V . Y . ;Chaikovskii, S. P. Kiner. Katal. 1972, 13, 1288; Kinef. Catal. (Engl. Transl.) 1972, 13, 1149. Fehrmann, R.; Krebs, B.; Papatheodorou, G. N.; Berg, R. W.; Bjerrum, N. J. Inorg. Chem. 1986, 25. 1571
Ir U
Figure 1. Reactor cell made of Pyrex for dynamic tests of catalytic melts: (A) inlet of gas flow; (B) bulb on main chamber; (C) glass-filter disk;
(D) bottom ampule for filtrate. system will be given e1~ewhere.l~The flow was introduced via stainiess steel tubes to the reactor cell placed in a furnace to establish a situation that simulated a working catalyst. The furnace was a tiltable doublequartz-walled transparent tube furnace, in which the temperature of the melt could be regulated to f 0 . 5 OC within the range 20-500 "C. The reactor cell, made of Pyrex (Figure l ) , was placed in the furnace at a position such that the bulb (B) was in the middle of the hot zone and the inlet and outlet seals were outside the furnace. A sufficiently slow gas flow passed through the inlet seal (A) and along the tube that heated the gas. Then it entered the reactor from below via a porous sintered glass-filter disk (C), bubbling through the melt (contained in the bulb B) and leaving the reactor through the outlet. This cell construction enabled us to separate precipitates on the filter disk (C) and isolate the melt filtrate in the bottom ampule (D) for separate analysis. Materials. The K2S20,used was synthesized by thermal decomposition of K2S208(Merck, maximum 0.001% N ) and stored in sealed ampules until used, as earlier de~cribed.~ The nonhygroscopic V 2 0 s (Cerac, Pure (99.9%)) was used without further purification. All handling of chemicals including the filling of the reactor cell was performed in a glovebox with a nitrogen atmosphere that was continuously dried to around 5 ppm H 2 0 by means of circulation through a column with molecular sieves. Commercial gases in steel bottles were used: SO2 (>99.9%), 0, (99.8% 0, + 0.2% N, and Ar), and N, ( 3.44) reflections (Mo Ka), R = 0.045; 9, Cs4H134Ag8SsP2, space group P21/c, a = 14.736 (8) A, b = 27.108 (4) A, c = 24.94 (2) A, B = 99.85 (3)O, V = 9815 (8) A', Z = 4, 5067 observed ( I > 341)) reflections (Mo Ka),R = 0.057; 10, C128Hls6Ag14S14P4(CHC13)2, space group P i , a = 13.523 (8) A, b = 13.852 (7) A, c = 21.808 (12) A, a = 79.86 (4)O, /3 = 86.08 (4)'. y = 85.75 (4)O, V=4004 (4) A', Z = I , 2690 observed ( I > 3 4 4 ) reflections (Mo Ka),R = 0.067.
Introduction Alkane- and arenethiolate compoundsMSR ofcopper and silver a r e still incompletely characterized structurally, largely d u e to difficulties with insolubility and poor crystal habit, and there are only a few crystal structure determinations for this long-known class of compounds.' O n e approach to the problem has been to 0020-1669/89/1328-1853$01.50/0
increase the steric bulk of the substituent R . Akerstrom showed that multiple branching and bulk in the thiolate substituent enhanced the solubilities of (MSR), in inert solvents and determined from ebullioscopic molecular weight measurements t h a t silver ( 1 ) Dance, I. G. Polyhedron 1986, 5 , 1037.
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