title: A discrete Cu cluster and a 3D MnII-CuIIframework based on assembly of Mn2Cu4clusters: synthesis, structure and magnetic properties.
abstract: The synthesis, single-crystal structure characterization and detailed magnetic study of a homometallic hexanuclear CuIIcluster [Cu6(μ3-OH)2(ppk)6(H2O)2(NO3)4] (1) and a three-dimensional (3D) compound [{MnCu2(dpkO2H)2(dpkO2)N3}·(NO3)·H2O]n(2) (ppk = phenyl-2-pyridyl ketoxime; dpk = di-2-pyridyl ketone) consisting of heterometallic MnII-CuIIhexanuclear cores as secondary building units are reported in this paper. In compound 1, two symmetry-related Cu3triangles consisting of a hydroxido-bridged trinuclear unit, [Cu3(μ3-OH)(ppk)3(H2O)(NO3)]+, are assembled through nitrate bridging giving rise to the homometallic Cu6cluster. Compound 2 contains heterometallic {MnCu} cores, which are further connected to each other through an azido bridging ligand in all the crystallographic directions, resulting in a 3D metal-organic framework. Construction of such a heterometallic 3D framework from {MnCu} units is until now, unknown. Magnetic studies of both 1 and 2 were performed in detail and both compounds show dominant antiferromagnetic interaction in the respective clusters. Compound 1 reveals significant spin frustration and anti-symmetric exchange interaction in the trinuclear cores, with a significantly high value of Jav(-655 cm-1). Furthermore, compound 2 exhibits a dominant antiferromagnetic interaction, which is also supported by an extensive magneto-structural correlation which considers the different magnetic pathways.
authors.affiliation: Molecular Materials Laboratory, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India. tmaji@jncasr.ac.in.
authors.forename: Anindita
authors.initials: A
authors.lastname: Chakraborty
authors.affiliation: Departament de Quimica Inorganica, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Escuer
authors.affiliation: Departament de Quimica Inorganica, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Ribas
authors.affiliation: Molecular Materials Laboratory, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India. tmaji@jncasr.ac.in.
authors.forename: Tapas Kumar
authors.initials: TK
authors.lastname: Maji