title: A Mn₁₅ single-molecule magnet consisting of a supertetrahedron incorporated in a loop.
abstract: Two new Mn(15) clusters consisting of a supertetrahedron which is incorporated in a loop are reported. The reactions of [Mn(O(2)CEt)(2)]·2H(2)O with the diols 1,3-propanediol (H(2)pd) or 2-methyl-1,3-propanediol (H(2)mpd) in the presence of KX (X = CN(-), Cl(-), Br(-), NO(3)(-), ClO(4)(-), OCN(-), SCN(-)) afforded compounds [Mn(15)K(mu(4)-O)(4)(O(2)CEt)(11)(pd)(12)(py)(2)] (1) and [Mn(15)K(mu(4)-O)(4)(O(2)CEt)(11)(mpd)(12)(py)(2)] (2). The structural core of 1 and 2 consists of a Mn(11) loop and a Mn(9)K supertetrahedron sharing a Mn(5) triangle. To the best of our knowledge, the structural motif of a supertetrahedron incorporated in a loop appears for the first time in metal cluster chemistry. Variable-temperature, solid-state direct current (dc) magnetic susceptibility studies in the 300-5 K range showed that the chi(M)T value increases with decreasing T suggesting the existence of predominant ferromagnetic exchange interactions and a relatively large ground state spin. This was confirmed by field-variable temperature magnetization measurements which were fitted using a matrix diagonalization method to give S approximately 23/2, g = 1.92(1) and D = -0.071(2) cm(-1). In addition, compound 1 displays frequency-dependent alternating current (ac) signals suggesting single-molecule magnetism (SMM) behaviour. This was proven by magnetization vs. dc field sweeps on single-crystals of 1·0.7py·1.3MeCN, which displayed sweep rate- and temperature-dependent hysteresis loops.
authors.affiliation: Department of Chemistry, University of Cyprus, 1678, Nicosia, Cyprus.
authors.forename: Eleni E
authors.initials: EE
authors.lastname: Moushi
authors.forename: Antonio
authors.initials: A
authors.lastname: Masello
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wernsdorfer
authors.forename: Vassilios
authors.initials: V
authors.lastname: Nastopoulos
authors.forename: George
authors.initials: G
authors.lastname: Christou
authors.forename: Anastasios J
authors.initials: AJ
authors.lastname: Tasiopoulos
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D008968:Molecular Conformation
chemical_list: D056831:Coordination Complexes; D008345:Manganese