Quadruple bridged-carbonate supported dodecanuclear [Ni8Ca4] coordination cluster†
Abstract
A dodecanuclear [Ni8Ca4] compound, [Ni8(L)8Ca4(CO3)4(dmf)5.5(H2O)6.5]·20H2O (1) (dmf = dimethylformamide) has been prepared by the reaction of a polydentate ligand (E)-2-(2-hydroxy-3-methoxybenzylidene)amino-4-nitrophenol (H2L) with NiCl2·6H2O, CaCl2·2H2O and Na2CO3 in dmf at room temperature. The solid-state molecular structure of compound 1 was determined by single crystal X-ray crystallography. Compound 1 consists of a [Ni8Ca4] coordination wheel with eight NiII ions and four CaII ions assembled by four carbonates and eight deprotonated L2− ligands. The asymmetric unit of compound 1 contains two NiII ions, one CaII ion, two coordinated deprotonated Schiff base ligands (L2−), one coordinated carbonate ion, two coordinated dmf molecules (one with occupancy of 0.36), two coordinated water molecules (one with occupancy 0.64). Compound 1 is the largest coordination cluster containing NiII and CaII ions reported to date. The magnetic properties of 1 show the presence of predominant antiferromagnetic interactions. The magnetic susceptibility and isothermal magnetization data can be well reproduced with: g = 2.145(1), J1 = 2.93(4) cm−1, J2 = −0.41(2) cm−1 and J3 = −5.66(4) cm−1.