title: Crystal structure and magnetic properties of a new chiral manganese(II) three-dimensional framework: Na(3)[Mn(3)(HCOO)(9)].
abstract: A structural and magnetic characterization of a trinuclear chiral Mn(II) formate three-dimensional framework exhibiting a triangular arrangement is presented. Compound Na(3)[Mn(3)(HCOO)(9)] was obtained by solvothermal synthesis and crystallizes in the chiral cubic space group P2(1)3 and is well described by a Delta conformation. The structure displays triangular Mn(3) building blocks, in which the metal centers are bonded by formate ligands in a syn-anti mode (Mn-Mn 5.697(1) A). The coordination sphere of manganese(II) is completed by six oxygen atoms from six formate ligands, resulting in an octahedral geometry. Magnetic susceptibility measurements showed antiferromagnetic interactions at high temperature and a strongly field dependent magnetic behavior below 40 K. At fields higher than 1.0 kOe only the antiferromagnetic interactions can be observed. At applied fields lower than 1.0 kOe magnetic susceptibility becomes irreversible with maxima observed at 22 and 34 K. These maxima suggest a weak ferromagnetic behavior because of spin canting, allowed by the presence of the noncentrosymmetric syn-anti HCOO bridges linking the Mn sites. This non-collinear antiferromagnetism and irreversible behavior can be due to the existence of a high degree of frustration in this unique lattice composed of linked triangular arrangements of interacting magnetic centers.
authors.affiliation: Departamento de Química, Universidad Tecnológica Metropolitana, Chile. vpg@manquehue.net
authors.forename: Verónica
authors.initials: V
authors.lastname: Paredes-García
authors.forename: Andrés
authors.initials: A
authors.lastname: Vega
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Novak
authors.forename: Maria G F
authors.initials: MG
authors.lastname: Vaz
authors.forename: Denise A
authors.initials: DA
authors.lastname: Souza
authors.forename: Diego
authors.initials: D
authors.lastname: Venegas-Yazigi
authors.forename: Evgenia
authors.initials: E
authors.lastname: Spodine
mesh_terms: D018360:Crystallography, X-Ray; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D017646:Organosilicon Compounds / Q000737:chemistry*; D013696:Temperature
chemical_list: D009942:Organometallic Compounds; D017646:Organosilicon Compounds; D008345:Manganese