Investigations of the TeCl4-(t)BuNHLi reaction: Synthesis, X-ray structures, and fluxional behavior of the tellurium-nitrogen compounds [Li2Te(N(t)Bu)(3)](2), {[LiTe(N(t)Bu)(2)(NH(t)Bu)]2LiCl}(2), and {Te-2(N(t)Bu)(4)[LiTe(N(t)Bu)(2)(NH(t)Bu)]LiCl}(2)

The reaction of (t)BuNHLi with TeCl4 in toluene at -78 degrees C produces (t)BuNTe(mu-N(t)Bu)(2)TeN(t)Bu (1) (55%) or [((t)BuNH)Te(mu-N(t)Bu)(2)TeN(t)Bu]Cl (2) (65%) for 4:1 or 7:2 molar ratios, respectively. The complex {Te-2(N(t)Bu)(4)[LiTe(N(t)Bu)(2)(NH(t)Bu)]LiCl}(2) (5) is obtained as a minor product (23%) from the 4:1 reaction. It is a centrosymmetric dimer in which each half consists of the tellurium diimide dimer 1 bonded through an exocyclic nitrogen atom to a molecule of LiTe(N(t)Bu)(2)(NH(t)Bu) which, in turn, is linked to a LiCl molecule. Crystals of 5 are monoclinic, of space group C2/c, with a = 27.680(6) Angstrom, b = 23.662(3) Angstrom, c = 12.989(2) Angstrom, beta = 96.32(2)degrees, V = 8455(2) Angstrom(3), and Z = 4. The final R and R(w) values were 0.046 and 0.047. At 65 degrees C in toluene solution, 5 dissociates into 1, LiCl, and {[LiTe(N(t)Bu)(2)(NH(t)Bu)]2LiCl}(2) (4), which may also be prepared by treatment of [Li2Te(N(t)Bu)(3)](2) (6) with 2 equiv of HCl gas. The centrosymmetric structure of 6 consists of a distorted hexagonal prism involving two pyramidal Te(N(t)Bu)(3)(2-) anions linked by four Li atoms to give a Te2N6Li4 cluster. Crystals of 6 are monoclinic, of space group P2(1)/c, with a = 10.194(2) Angstrom, b = 17.135(3) Angstrom, c = 10.482(2) Angstrom, beta = 109.21(1)degrees V = 1729.0(5) Angstrom(3), and Z = 2. The final R and R(w) values were 0.026 and 0.023. VT H-1 and Li-7 NMR studies reveal that, unlike 1, compounds 2, 4, and 6 are fluxional molecules. Possible mechanisms for these fluxional processes are discussed.