Inorg. Chem. 1992, 31, 3963-3970
3963
Immobilization of Thallium by Tandem Oxidation/Reduction-Complexation of Thallium(I/III) Ishenkumba A. Kabwa,'*t Dionne Miller,+**Maurene Mitchel,t*sFrank R. Fronczek,s R. C. Coodrich,ll David J. Williams,* Caroline A. O'Mahoney,l Alexandra M. Z. Slawin,l Steven V. Ley,* and Christopher J. Croombridgd Departments of Chemistry, University of the West Indies, Mona, Kingston 7, Jamaica, Louisiana State University, Baton Rouge, Louisiana 70803, Imperial College of Science, Technology and Medicine, South Kensington, London S W 7 2AY, U.K., and Royal Holloway and New Bedford College, Egham, Surrey TW 20 OEX,U.K., and Department of Physics, Louisiana State University, Baton Rouge, Louisiana 70803
Received December 6, I990 Development of management procedures for toxic superconducting thallium+opper-alkaline earth ceramics and their byproductsrequires better understanding of the complexometric chemistry of thallium in the presence of copper and alkaline earth cations. This study reveals that thallium can be immobilized as a thallium-rich mixed-valence solid [(T118~6)4CuC14][TlC14]~nH20 (1,n=0;2,n= 0.25). WheneitherTl(I)orTl(III) is treatedwith 18-crown-6 ( 1 8 ~ 6 in ) the presence of copper(I1) (or zinc) chloride, tandem oxidation (or reduction) complexation occurs to an extent sufficient to form 1 and/or 2. The divalent transition metal ion (M) plays a beneficial role of concentrating TI+ as a cation [(T118C6)4MC14I2+,M = Cu or Zn. The template concerted reduction/oxidation+omplexation reactions appear to take advantage of the high stability of the TIC&- anions. Similar complexes are obtained if C1is replaced by B r , T1+ by Rb+, and Cu2+by Mn2+and Co2+. The crystal structures of 1,2, (Rb18c6)2Cu2Cls (5), and (Ba18~6)2(CuC1&.3HzO(6) along withsolid-statethallium-205 NMRspectraof 1,2, [(T118c6)4ZnC14] [T1C&l2 (3), and [(Rbl8~6)4CuCl4][TlCl4]2 (4) are reported. The cubic (F23) complexes 1, 2, and 4 feature a roomtemperature average Td geometry for CuC1d2- anions, and the Td nature (required by symmetry) of the position it occupies is confirmed by the luminescence of Td MnC14*- and the blue color of Td CoC1d2- ions substituting for C U C ~species. ~ ~ - Crystal data are as follows. 1: cubic, space group F23 with a = 20.728 (2) A, V = 8905.1 (9) A3, and Z = 4; with 661 reflections having I > la(I), R = 0.038. 2: cubic, space group F23 with a = 20.748 (5) A, V = 8932 A3, Z = 4; with 549 independent reflections having IFoI > 3a(lFoI),R = 0.043. 5: monoclinic, space group P 2 l / c with a = 11.100 (2) A, b = 8.168 (1) A, c = 22.626 (5) A, 4 = 97.55 (2)O, V = 2034 A3, and Z = 2; with 2456 reflections (IFoI > 3a(lFoI)), R = 0.042. 6: triclinic Pi with a = 8.757 (3) A, b = 17.174 (5) A, c = 17.616 (6) A, a = 66.23 (3)O, 4 = 77.31 (3)O, y = 75.71 (2)", V = 2327.9 (13) A, and Z = 2; using 6214 reflections ( I > 3u(I)), R = 0.051.
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Introduction The recent discovery of various thallium-based multicomponent superconductingceramic oxides with critical transition temperatures (Tc) in the range 73-125 K has stimulated intense research interest in thallium-copper oxides as alternatives to the lanthanide-based superconductingceramics.Id Whereas the thallium superconducting ceramics, especially those having the stoichiometries Tl2BazCaFu3010(Tc = 120-125 K)2 and T12Ba2CaCu2Os (Tc = 100-105 K)' have significant advantages over ~~
~
~
~
~~
the more popular YBa2Cu30, ( T 93 K)7-9 such as a higher Tc and ease of preparation, the extreme toxicity of thallium is a major concern.1° Therefore, when large scale or regular usage of thallium compounds in the development, manufacture, and application of superconducting copper oxide ceramics is contemplated, detoxificationand clean up procedures for which the feedstocks would be mixtures of many metal ions must also be considered. For this effort, better understandingof thechemistry of thallium in the presence of key metal ions such as Cu2+and the alkaline earth cations is needed. We have investigated the complexation of thallium cations (T1+ and T P ) by 18-crown-6 (18c6) in the presence of copper(11) and barium(I1) to determine the influence of these cations on the extractibility or immobilization of thallium. Our choice for 18c6 as a complexing agent was inspired by a large volume of studies involving this readily availablecrown ether which have demonstrated its remarkable versatility for the complexation and transport of M+ and M2+~ a t i o n s . l l - ~In~fact, the 18c6 cavity has recently been bonded on solid polymeric supports and found
University of the West Indies. Partial fulfillment of requirements for the BSc. degree, University of the West Indies. f Department of Chemistry, Louisiana State University. 1 Department of Physics, Louisiana State University. * Imperial College. X Royal Holloway and New Bedford College. Current address: B. P. International Ltd., Sunbury Research Center, Chertsey Road, Sun-on-Thames, Middlesex TW16 7LN, U.K. (1) Subramanian, M. A.; Calabrese, J.; Torardi, C. C.; Gopalakrishnan, J.; Askew, T. R.; Flippen, R. B.; Morrissey, K. J.; Chowdhry, U.; Sleight, A. W. Nature 1988,332,420. (7) Wu, M. K.; Ashburn, J. R.; Tomg, C. J.; Hor, P. H.; Meng, R. L.; Gao, (2) Toradi, C. C.; Subramanian, M. A.; Calabrese, J. C.; Gopalakrishnan, L.; Huang, Z. J.; Wang, Y. Q.;Chu, C. W. Phys. Reu. Lett. 1987,58, J.;Morrissey,K. J.;Askew,T.R.;Flippen,R.B.;Chowdhry,U.;Sleight, 908. A. W. Science 1988,240, 631. (8) Kahwa, I. A.; Goodrich, R. G. J . Muter. Sci. Lett. 1989, 8, 755. (3) H a m , R. M.; Angel, R. J.; Prewitt, C. T.; Ross, N. L.;Hadidiacos, C. (9) Her, P. H.; Gas, L.; Meng, R. L.; Huang, Z. J.; Wang, Y.0.;Foster, G.; Heaney. P. J.; Veblen, D. R.; Sheng, Z. Z.; El Ali, A.; Herman, A. K.; Vassiliow, J.; Chu, C. W. Phys. Rev. Lett. 1987, 58, 911. M. Phys. Reo. Lett. 1988, 60, 1657. (IO) Wade, K.; Banister, A. J. In ComprehensiueInorgunic Chemistry; Bailar, (4) Parkin, S.S.;Lee, V. Y.; Nazzal, A. I.; Savoy, R.; Beyers, R.; La Placa, J. C., Jr., EmelCus, H. J., Nyholm, R., Trotman-Dickenson, A. F.,Eds.; S.J. Phys. Reu. Lett. 1988, 60, 2539. Pegamon Press: London, 1973; Vol. 1, p 1124. (5) Sheng, Z. 2.;Hermann, A. M. Nuture 1988,332, 55. ( 1 1) Pederson, C. J. J . Am. Chem. SOC.1967, 89, 7017. Pedersen, C. J.; (6) Sheng, Z. Z.; Hermann, A. M. Nufure 1988, 332, 138. Frensdorff, H. K. Angew. Chem., Int. Ed. Engl. 1972, 11, 16. f
0020-1669/92/ 1331-3963$03.00/0
0 1992 American Chemical Society
3964 Inorganic Chemistry, Vol. 31, No. 19, 1992
Kahwa et al.
Table I. Crystallography Data
"pd temp, K empirical formula fw cryst system space group lattice consts a, A b, A
2
1
5
295 C48Cli~CUH96024Tls 2772.5 cubic n 3
297 297 296 C4scli ~ C U H % . @ N . ~ S T ~ ~ C ~ ~ C ~ S C U ~ H ~ S O I B ~ ~R~~C~~ ~ C ~ S C I I ~ H M O I S 2777.0 1039.4 1268.1 cubic monoclinic triclinic n 3 Rl/C Pi
20.728 (2)
20.748 (5)
11.100 (2) 8.168 (1) 22.626 (5)
c, A
a,deg
6, deg
97.55 (2)
79 deg
v,A3
dcalc,g/mL dobrg/mL 2 abs coeff ( p ) , cm-I radiation (A, A) 0 limits, deg no. of unique reflcns no. of obsd reflcns R RW
6
8905.1 (9) 2.068 2.048 4 115.9 Mo Ka (0.710 73) i
