title: Linear NiII-MnIII2-NiII tetramers: an oligomeric component of the MnIII2NiII single-chain magnets.
abstract: Heterometallic linear tetramers [Mn(5-R-saltmen)Ni(pao)(bpy)(2)](2)(ClO(4))(4) (5-R-saltmen(2-) = N,N'-1,1,2,2-tetramethylethylene bis(5-R-salicylideneiminate); pao(-) = pyridine-2-aldoximate; bpy = 2,2'-bipyridine, R = H, 1; Cl, 2; Br, 3; MeO, 4) have been synthesized and structurally characterized. These compounds exhibit a [Ni(II)-NO-Mn(III)-(O)(2)-Mn(III)-ON-Ni(II)] skeleton where -ON- is an oximate bridge between Mn(III) and Ni(II) ions and -(O)(2)- is a bi-phenolate bridge between Mn(III) ions. These tetramers can be seen as oligomeric units of the heterometallic Mn(III)(2)-Ni(II) chain observed in a family of single-chain magnets (Clérac, R.; Miyasaka, H.; Yamashita, M.; Coulon, C. J. Am. Chem. Soc. 2002, 124, 12837. Miyasaka, H.; Clérac, R.; Mizushima, K.; Sugiura, K.; Yamashita, M.; Wernsdorfer, W.; Coulon, C. Inorg. Chem. 2003, 42, 8203.). Magnetic measurements on these tetramers confirm the nature of the magnetic interactions reported for the Mn(III)(2)-Ni(II) chains: a strong antiferromagnetic Mn(III)/Ni(II) coupling via the oximate bridge (J(Ni-Mn) ranges from -23.7 to -26.1 K) and a weak ferromagnetic Mn(III)/Mn(III) coupling through the bi-phenolate bridge (J(Mn-Mn) ranges from +0.4 to +0.9 K). These magnetic interactions lead to tetramers with an S = 2 ground state.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397, Japan. miyasaka@comp.metro-u.ac.jp
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Miyasaka
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Nezu
authors.forename: Kunihisa
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Sugiura
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamashita
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Clérac
mesh_terms: D002614:Chelating Agents / Q000138:chemical synthesis / Q000737:chemistry; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D013696:Temperature
chemical_list: D002614:Chelating Agents; D009942:Organometallic Compounds; D008345:Manganese; D009532:Nickel