Syntheses, structures, and magnetic properties of inorganic-organic hybrid cobalt(II) phosphites containing bifunctional ligands

Seven new cobalt(II) phosphites, [Co(HPO3)(C14H14N4)(H2O)(2)]center dot 2H(2)O (1), [Co(HPO3)(C22H18N4)]center dot H2O (2), [Co-2(HPO3)(2)(C22H18N4)(2)H2O]center dot H2O (3), [Co-2(HPO3)(2)(C12H10N4)(1.5)H2O]center dot 1.5H(2)O (4), [Co(HPO3)(C14H14N4)(0.5)]center dot H2O (5), [Co(HPO3)(C18H16N4)(0.5)] (6), and [Co(HPO3)(C18H16N4)(0.5)] (7) were synthesized in the presence of 1,2-bis(imidazol-1-ylmethyl) benzene (L1), 1,4-bis(benzimidazol-1-ylmethyl)benzene (L2), 1,3-bis(benzimidazol-1-ylmethyl)benzene (D), 1,4-bis(1-imidazolyl)benzene (L4), 1,4-bis(imidazol-1-ylmethyl) benzene (L5), 1,4-bis(imidazol-1-ylmethyl) naphthalene (L6), and 1,5-bis(imidazol-1-ylmethyl) naphthalene (L7), respectively, and their structures were determined by X-ray crystallography. Compound 1 is a molecular compound in which two cobalt(II) ions are held together by double mu-O linkages. The inorganic framework of compounds 2 and 3 are composed of vertex-shared CoO2N2/CoO3N2 and HPO3 polyhedra that form four rings; these are further linked by an organic ligand to generate 2D sheets. Compounds 4 and 5 both have 1D inorganic structures, with the bifunctional ligands connected to each side of the ladder by coordination bonds to give 2D hybrid sheets, A 3D organically pillared hybrid framework is observed in 6 and 7. In 6, the stacking of the interlayer pillars gives rise to a small hydrophobic channel that extends through the entire structure parallel to the sheets. The temperature-dependent magnetic susceptibility measurements of these compounds show weak interactions between the metal centers, mediated through the mu-O and/or O-P-O linkages.