ORIGINAL PAPER Cations Insertion in Molybdenum Cluster Compounds: Electronic Structure and Electrochemical Study Using Cavity Microelectrode Sofiane Bouazza Diala Salloum Re ´gis Gautier Patrick Gougeon Michel Potel Didier Hauchard Received: 1 September 2008 / Published online: 22 October 2008 Ó Springer Science+Business Media, LLC 2008 Abstract Owing to the high lability of cations in the three-dimensional framework of K 1?x Mo 12 S 14 (0 B x B 1.6), first-principles calculations and electrochemical methods have been carried out to study the insertion of cations in the empty channels of this compound. The cavity microelectrode that is a suitable electrode for powder material analysis has been used in voltammetric experiments. Results obtained for Li ? , Na ? , Rb ? ,K ? , Cs ? and NH 4 ? cations are presented and discussed. Keywords Molybdenum clusters  Cation insertion  Electronic structure  Cavity microelectrode  Electrochemistry Introduction Solid-state ternary and quaternary chalcogenide compounds in which the molyb- denum is present in low formal oxidation states are generally characterized by metal–metal bonds which give rise to the formation of discrete clusters of diverse sizes and geometries or infinite chains. The most frequently encountered cluster is the Mo 6 octahedron observed, for example, in the ternary reduced molybdenum chalcogenides M x Mo 6 X 8 (M = Na, K, Ca, Sr, Ba, 3d, rare-earth, Sn, Pb…;X = S, Se, Te) [1]. Molybdenum clusters with nuclearity higher than six such as Mo 9 [2], Mo 12 [3, 4], Mo 15 [5, 6], Mo 18 [7], Mo 21 [8], Mo 24 [9], Mo 30 [9], and Mo 36 [10] result from the uniaxial trans-face sharing of Mo 6 octahedra. Most of the S. Bouazza  D. Salloum  R. Gautier  P. Gougeon  M. Potel  D. Hauchard (&) Sciences Chimiques de Rennes, UMR 6226, CNRS—Universite ´ de Rennes 1—Ecole Nationale Supe ´rieure de Chimie de Rennes, Avenue du Ge ´ne ´ral Leclerc, 35700 Rennes, France e-mail: didier.hauchard@ensc-rennes.fr Present Address: S. Bouazza Lehrstuhl fu ¨r Werkstoffverarbeitung, University of Bayreuth, FAN-C 95440 Bayreuth, Germany 123 J Clust Sci (2009) 20:133–143 DOI 10.1007/s10876-008-0211-8