Hydrides, Halides, and Polymers: Some Unexpected Intermediates on the Routes to First-Row Transition Metal M{N(SiMe3)2}n (n=2, 3) Complexes

The reaction of 2 equiv of LiN(SiMe3)(2)center dot Et2O with TiCl3(NMe3)(2) or VCl3(NMe3)(2) afforded the dimeric, halide bridged complexes [Ti(mu-Cl){N(SiMe3)(2)}(2)](2) (1) or [V(mu-Cl){N-(SiMe3)(2)}(2)](2) ( 2 ) in moderate yields. The reduction of titanium complex 1 with 3 equiv of 5% (wt) Na/NaCl gave the mixed metal titanium/sodium hydride cluster Ti-2(mu-H)(2) {N(SiMe3)(2)}(3){N-(SiMe3)(SiMe2CH)}(Na) (3), which was formed by activation of two C-H bonds at a single methyl group of one of the bis(trimethylsilyl)amide ligands. Attempts to form the analogous vanadium complex by reduction of 2 gave only intractable products. Treatment of Co{N(SiMe3)(2)}(2) with 1 equiv of BrN(SiMe3)(2) (which was previously shown to give the unique three-coordinate cobalt(III) trisamide Co{N(SiMe3)(2)}(3)) afforded the polymeric [(mu-Br)Co{mu-N(SiMe3)(SiMe2CH2CH2Me2Si)(Me3Si)mu-N}Co(mu-Br)](infinity), (4) as a second product, which was shown by a structural analysis to possess a carbon-carbon bond formed between the two ligands. Attempts to isolate manganese and iron complexes analogous to 4 were unsuccessful. The role of bromine in these reactions was further studied by examining the reaction of 0.5 equiv of elemental bromine with [Mn{N(SiMe3)(2)}(2)](2) or [Co{N(SiMe3)(2)}(2)](2), which for manganese was shown to give the previously reported manganese trisamide Mn{N(SiMe3)(2)}(3) but for cobalt gives the dimeric amide-bridged [Co(Br){mu-N(SiMe3)(2)}](2)(5).

Automated summary

The reactions involving different metal complexes led to the formation of a variety of metal amide compounds with diverse structures and properties, including polymers of titanium and cobalt, as well as dimers of manganese and iron. The role of elemental bromine in these reactions was studied, revealing its impact on ligand activation and the formation process of metal complexes.