PI-COMPLEXES OF HEAVY-METALS .10. SYNTHES IS AND CRYSTAL-STRUCTURE OF([(1,3,5-(CH3)(3)C6H3)(2)TL][ALCL4])(2) - AN ARENE STABILIZED DIMERICTHALLIUM(I) TETRACHLOROALUMINATE

From a solution of AlCl3 and TlCl in mesitylene, the bis(arene)thalliu m complex {[(1,3,5-(CH3)(3)C6H3)(2)Tl][AlCl4]}(2) (1) (space group P2( 1)/c with a=19.575(4) Angstrom, b=12.436(2) Angstrom, c=19.415(4) Angs trom, beta=101.69(3)degrees at T=-90+/-1 degrees C; Z=4) will crystall ize at low temperature. This compound can be described as a dimeric th allium(I) tetrachloroaluminate with a sceleton similar to that of (TeI 4)(4), shielded by four arenes, in pairs coordinated at the thallium a toms. In the solid state the complete configuration has point group sy mmetry 1 (C-1). Tl-Cl distances ranging from 3.292(3) to 3.679(3) Angs trom point out an ionic bonding situation between arene(2)Tl(+) and Al Cl4- fragments. The strengths of the eta(6) like Tl-arene interactions are characterized by distances Tl(1)-C of 3.250 Angstrom and 3.315 An gstrom, and Tl(2)-C of 3.285 Angstrom and 3.328 Angstrom and a tempera ture of release of all arene molecules of 61 degrees C, which has been determined by differential thermal analysis, to yield pure thallium(I ) tetrachloroaluminate.