Charge transfer in misfit layer chalcogenides, [(MX)n]1+x(TX2)m:: a key for understanding their stability and properties

Stability of misfit layer chalcogenides (M.L.C.) is always governed by a charge transfer (C.T.) mechanism. A comparison between M.L.C. and parent intercalated layered binary systems shows comparable characteristics, which illustrate the role of electron donor for the MX part (or its corresponding A-intercalant species) towards the TX2 acceptor part. In that way, intercalation chemistry within the vdW gap of multilayered TX2 misfit derivatives is also considered. The donor character of the MX part, easy to understand when trivalent M cations are present, can be also assumed if a divalent M cation is partly substituted for a trivalent one, as revealed from precise electron microprobe analysis. Examples of M.L.C. with enlarged MX part (with mixed M+II, M+III) emphasize the reality of the C.T.. This M-to-T donor effect necessarily controls the transport and intercalation properties.