Oxalate and 2,2'-bipyrimidine as bischelating ligands in the honeycomb layered compound {[Fe2(bpym)(ox)2] . 5H2O}

The novel two-dimensional iron(II) compound of formula {[Fe-2(bpym)(ox)(2)].5H(2)O}(n) (1) [bpym = 2,2'-bipyrimidine and ox = oxalate dianion] is obtained by reaction of oxalic acid, iron(II) chloride and 2,2'-bipyrimidine in aqueous solution. The structure of 1 is made up of oxalato-bridged iron(II) chains cross-linked by bischelating bpym affording a honeycomb lattice. Variable-temperature magnetic susceptibility data of 1 show the occurrence of relatively large antiferromagnetic interactions between the high spin iron(II) ions separated by more than 5.5 Angstrom through bridging bpym [J(bpym) = 4.0(2) cm(-1)] and ox [J(ox) = ca. -7.8( 2) cm(-1)] ligands. These values compare well with those obtained in the iron(II) chain [Fe(dpa)(ox)]n ( 2) [J(ox) = -8.0(2) cm(-1)] (dpa = 2,2'-dipyridylamine) and dinuclear {[Fe(H2O)(4)](2)(bpym)}(SO4)(2).2H(2)O(3) (J(bpym) = 3.4 cm(-1)) compounds where bischelating ox (1 and 2) and bpym (1 and 3) groups and the bidentate dpa (2) ligand are present.