SYNTHESIS AND CHARACTERIZATION OF STERICALLY ENCUMBERED LI, NA, AND K-ARYL TELLUROLATES, AND SOME PT(II), IR(I), AND CD(II) DERIVATIVES

The synthesis, isolation, and characterization of several alkali metal aryl tellurolates of general formula (2,4,6-R3C6H2)TeM(sol)n (R = Me, (i)Pr, (t)Bu; M = Li, Na, K; sol = THF, n = 1.33, 1.5, 2.5, 3; sol = DME, n = 1; sol = TMEDA, n = 1; sol = 18-crown-6, n = 1) is reported. Reduction of (2,4,6-Me3C6H2)2Te2 and ((2,4,6-Pr3C6H2)2Te2)-Pr-i with 2 equiv of LiEt3BH in THF affords the corresponding lithium tellurolates 1 and 2. Direct Te insertion into the C-Li bond of (2,4,6-tBu3C6H2)Li(THF)3 in THF produces 3, while a similar reaction of Te metal with (o-C6H4CH2NMe2)Li affords the chelating tellurolate, 4. The action of Na/Hg amalgam on THF solutions of (2,4,6-Me3C6H2)2Te2 or ((2,4,6-Pr3C6H2)2Te2)-Pr-i followed by work-up with TMEDA or DME leads to the sodium tellurolates 5 and 6 respectively. Treatment of THF solutions of ((2,4,6-Pr3C6H2)2Te2)-Pr-i with 2 equiv. of KsBu3BH gives the polymeric tellurolate, ((2,4,6-Pr3C6H2)2TeK(THF)1.33)-Pr-i, (7). The infinite ladder-like structure is broken by reaction with 18-crown-6, which affords the monomeric derivative, 8. Reaction of 2 or 3 with THF suspensions of cis-(PPh3)2PtCl2 produces the air-stable cis-platinum tellurolates, 9 and 10, respectively. Reaction of 3 with trans-(PPh3)2Ir(CO)Cl, leads to the isolation of 11, a rare example of a Vaska's type complex with a cis-geometry, and only the second such structurally characterized derivative. Reaction of 4 with 1/2 equiv. of CdBr2 produces 12, Cd[Te(o-C6H4CH2NMe2)]2. Compounds 3, 4, 7, 10, and 11 have been characterized by single crystal X-ray diffraction.