UNUSUAL ETA-6-TOLUENE COORDINATION TO AN ALKALI-METAL - X-RAY CRYSTAL-STRUCTURE OF LU(CH(SIME3)2)3(MU-CL)K(ETA-6-C7H8)2 AND THE SOLUBILIZATION OF UNSOLVATED ALKALI-METAL HALIDES IN HYDROCARBON MEDIA

Reaction of Lu{CH(SiMe3)2}3 (1) with KCl in ether, or reaction of LuCl3 with KCH(SiMe3)2 (3 equiv) in ether, affords Lu{CH(SiMe3)2}3(mu-Cl)K(ether) (2). Coordinated ether is readily removed from 2 under vacuum to afford Lu{CH(SiMe3)2}3(mu-Cl)K (3), which contains coordinated KCl that is not stabilized by a donor ligand. Reaction of 1 with KBr yields Lu{CH(SiMe3)2}3(mu-Br)K(ether) (4), which can be converted to Lu{CH(SiMe3)2}3(mu-Br)K(C7H8) (5). Dissolution of 3 in toluene affords Lu{CH(SiMe3)2}3(mu-Cl)K(C7H8)2 (6). Stepwise removal of coordinated toluene from 6 can be achieved, first to give the mono(toluene) adduct Lu{CH(SiMe3)2}3(mu-Cl)K(C7H8) (7), and finally to 3. Compound 6 crystallizes in space group P1BAR (No. 2), with a = 12.0060 (12) angstrom, b = 13.9624 (14) angstrom, c = 16.5370 (42) angstrom, alpha = 105.44 (4)degrees, beta = 99.77 (7)degrees, gamma = 106.27 (10)degrees, V = 2474 angstrom 3, and Z = 2. The current R = 0.051 and R(W) = 0.061 for 6445 independent reflections with I > 2.5-sigma(I). 6 shows unusual eta-6 coordination of both toluenes to potassium. In contrast, neither La{CH(SiMe3)2}3 nor Lu(C5Me5)2CH(SiMe3)2 reacts with KCl in ether.