Reactions of cis-[tBuNTe(μ-NtBu)]2 with CF3SO3Me and M[O3SCF3] (M = Ag, Cu): Chelation, Cis → Trans Isomerization, and the Spirocyclic Ligand [tBuNTe(μ-NtBu)2Te(μ-O)]2

The first investigations of coordination complexes of the tellurium diimide dimer [(t)BuNTe(-N(t)Bu)](2) (1a) are presented. The coinage metals Ag(+) and Cu(+) were chosen to evaluate the ability of 1a to function as a chelating or bridging ligand. Reaction of 1a with Ag[O(3)SCF(3)] in toluene produces [Ag(2)L(2)][O(3)SCF(3)](2) (5, L = 1a) or, in the presence of LiCl, [Ag(2)L(2)(-Cl)][O(3)SCF(3)] (3). In 4 the two Ag(+) ions bridge two molecules of cis-1a and engage in a weak Ag.Ag bonding interaction. In 3 the Cl(-) ion bridges two Ag(+) ions, which are each chelated to the terminal N(t)Bu groups of 1a. Treatment of 1a with Cu[O(3)SCF(3)] in toluene yields {[CuL][CF(3)SO(3)]}(n)() (5) which, in turn, reacts with 1a to form [Cu(2)L(3)][CF(3)SO(3)](2) (6). In 6 the two Cu(+) ions bridge cis and trans forms of 1a. The hydrolysis products {[(t)BuNTe(-N(t)Bu)(2)Te(-O)](2)[M(H(2)N(t)Bu)](2)}[O(3)SCF(3)](2) (7a, M = Ag; 7b, M = Cu) and [Cu(2)L((t)BuNH(2))(2)][O(3)SCF(3)](2) (8) were also structurally characterized. The complexes 7a,b contain the dimer [(t)BuNTe(-N(t)Bu)(2)(-O)](2) in which one of the terminal N(t)Bu ligands in 1a is replaced by an O atom. The central Te(2)O(2) ring in this spirocyclic ligand is planar with unsymmetrical oxygen bridging [d(Te-O) = 1.885(7) and 2.170(7) Å in 7b]. The ligand 1a in 8 is in the trans conformation. Mono- or dimethylation of 1a with CF(3)SO(3)Me was shown to occur at the terminal nitrogens by (1)H and (125)Te NMR spectroscopy.