title: Half-integer spin heptanuclear single-molecule magnet with an unusual Mn(III)6Mn(II) exchange-coupled core.
abstract: The synthesis, X-ray crystallography, magnetic properties, and high-field electron paramagnetic resonance (HFEPR) of a new heptanuclear manganese complex [Mn(7)(heamp)(6)](ClO(4))(2)·4CH(2)Cl(2)·H(2)O (complex 2), in which heampH(3) is 2-[N,N-di(2-hydroxyethyl)aminomethyl]phenol (compound 1), is reported. Complex 2 has a hexagonal, disk-shaped topology and contains six Mn(III) ions and a central Mn(II) ion. It crystallizes in the monoclinic space group P2(1)/c with two molecular orientations. Consideration of the cluster topology, together with variable-temperature and variable-field DC magnetic susceptibility data, suggest that complex 2 exists in a half-integer, S = (19)/(2) ± 1 spin ground state, with appreciable uniaxial zero-field splitting (D = -0.16 cm(-1)). AC magnetic susceptibility measurements clearly show out-of-phase signals, which are frequency- and temperature-dependent, indicating slow magnetization relaxation behavior. An analysis of the relaxation data employing the Arrhenius formula yielded an effective relaxation barrier of 12.9 cm(-1). Simulations of HFEPR studies agree with the assignment of an S ≈ (19)/(2) spin ground state, with g = 1.96, D = -4.71 GHz (-0.16 cm(-1)), and a longitudinal fourth-order zero-field splitting parameter B(4)(0) = -2.7 × 10(-4) GHz (-9.0 × 10(-6) cm(-1)).
authors.affiliation: Department of Chemistry, Fu Jen Catholic University, Hsinchuang, Taipei, 24205, Taiwan, Republic of China.
authors.forename: Siou-Yin
authors.initials: SY
authors.lastname: Chen
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Beedle
authors.forename: Pei-Rung
authors.initials: PR
authors.lastname: Gan
authors.forename: Gene-Hsian
authors.initials: GH
authors.lastname: Lee
authors.forename: Stephen
authors.initials: S
authors.lastname: Hill
authors.forename: En-Che
authors.initials: EC
authors.lastname: Yang
mesh_terms: D004983:Ethanolamines / Q000737:chemistry; D008024:Ligands; D059346:Magnets / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D019800:Phenol / Q000737:chemistry
chemical_list: D004983:Ethanolamines; D008024:Ligands; D009942:Organometallic Compounds; D019800:Phenol; D008345:Manganese; C020283:diethanolamine