Intercalation of methylamines into titanium disulfide

The reactions of methylamine, dimethylamine, and trimethylamine with TIS2 w ere characterized by several techniques. Detailed studies of the intercalat ion of methylamine demonstrated that the reaction was of the redox-rearrang ement type, where the intercalate is best described as (CH3NH3+)(y') (CH3NH 2)(y") TiS2y'(-), with y' = 0.25+/-0.02 and y" dependent on sample history. For y' = 0.25 and y"= 0.15, this intercalate is a mixed-phase stage 1 [a = 3.422(5) Angstrom and c 28.06(10) Angstrom] and stage 2 [a = 3.4265 Angstr om and c = 42.48(10) Angstrom] compound having R (3) over barm symmetry. Vi sual observation and thermogravimetric analysis of dimethylamine intercalat ion also suggest a redox-rearrangement mechanism, In contrast, no intercala tion was observed for trimethylamine. The onset time for intercalation of l iquid amines into TIS, at ambient temperature follows the general trend: N2 H4< NH3< CH3NH2< (CH3)(2)NH<< (CH3)(3)N. This trend is consistent with an i ncrease in steric hindrance about the N atom and decrease in the number of amine hydrogen atoms that effectively reduces the nucleophilic reaction rat e of the intercalant. (C) Academic Press.