title: A two-dimensional oxamate- and oxalate-bridged Cu(II)Mn(II) motif: crystal structure and magnetic properties of (Bu4N)2[Mn2{Cu(opba)}2ox].
abstract: A new compound of formula (Bu4N)2[Mn2{Cu(opba)}2ox] (1) [Bu4N(+) = tetra-n-butylammonium cation, H4opba = 1,2-phenylenebis(oxamic acid), and H2ox = oxalic acid] has been synthesized and magneto-structurally investigated. The reaction of manganese(II) acetate, [Cu(opba)](2-), and ox(2-) in dimethyl sulfoxide yielded single crystals of 1. The structure of 1 consists of heterobimetallic oxamato-bridged Cu(II)Mn(II) chains which are connected through bis-bidentate oxalate coordinated to the manganese(II) ions to afford anionic heterobimetallic layers of 6(3)-hcb net topology. The layers are interleaved by n-Bu4N(+) counterions. Each copper(II) ion in 1 is four-coordinate in a square planar environment defined by two amidate-nitrogen and two carboxylate-oxygen atoms from the two oxamate groups of the obpa ligand. The manganese(II) ion is six-coordinate in a somewhat distorted octahedral surrounding that is built by two oxalate-oxygen and four carbonyl-oxygen atoms from two [Cu(opba)](2-) units. The magnetic properties of 1 in the temperature range 1.9-300 K correspond to those expected for the coexistence of intralayer antiferromagnetic interactions of the type copper(II)-manganese(II) across oxamato and manganese(II)-manganese(II) through oxalato bridges plus a weak spin canting in the very low temperature domain. Simulation of the magnetic data through quantum Monte Carlo methodology reveals the magnitude of the intralayer magnetic interactions [J(CuMn) = -32.5(3) cm(-1), and J(MnMn) = -2.7(3) cm(-1)], their values being within the range of those previously observed in lower nuclearity systems.
authors.affiliation: Departament de Química Inorgànica/Instituto de Ciencia Molecular, Facultat de Química de la Universitat de València, 46980-Paterna (València), Spain.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Marinho
authors.forename: Tatiana R G
authors.initials: TR
authors.lastname: Simões
authors.forename: Marcos A
authors.initials: MA
authors.lastname: Ribeiro
authors.forename: Cynthia L M
authors.initials: CL
authors.lastname: Pereira
authors.forename: Flávia C
authors.initials: FC
authors.lastname: Machado
authors.forename: Carlos B
authors.initials: CB
authors.lastname: Pinheiro
authors.forename: Humberto O
authors.initials: HO
authors.lastname: Stumpf
authors.forename: Joan
authors.initials: J
authors.lastname: Cano
authors.forename: Francesc
authors.initials: F
authors.lastname: Lloret
authors.forename: Miguel
authors.initials: M
authors.lastname: Julve