The electrical and magnetic properties of misfit layered cobaltocene complexes of composition (PbS)(1.18)(TiS2)(2)(CoCp2)(0.28), (PbS)(1.14)(TaS2)(2)(CoCp2)(0.28), and (PbSe)(1.12)(NbSe2)(2)(CoCp2)(0.27) [Cp = C5H5-] were investigated. All the pristine chalcogenides studied exhibit a metallic behavior and a magnetic susceptibility virtually independent of temperature. Moreover, the Ta and Nb compounds-the later impurified with NbSe2-undergo a superconducting transition at low temperatures (T-C <4 K). Upon cobaltocene intercalation, the Ta and Nb systems behave similarly. The superconducting transition temperature changes very little and the metallic behavior is preserved: the susceptibility is temperature-independent, whereas the resistivity increases with increasing temperature. This is consistent with an electron transfer from the metallocene to the host. The Ti intercalate behaves markedly differently. Thus, the complex undergoes a metal semiconducting transition below 70 K, and the magnetic data are significantly temperature-dependent. This localized moment may be consistent with the minimum observed in the resistivity values. The good overlapping properties 4d and 5d orbitals relative to 3d orbitals may account for the delocalization of the electron donated by the guest to the conduction band of the host.
|Pages (from-to)||2737 - 2742|
|Number of pages||6|
|Journal||Chemistry of Materials|
|Publication status||Published - Oct-1999|