A novel co-ordination mode for the squarate ligand [dihydroxycyclobutenedionate(2–)]: synthesis, crystal structure, and magnetic properties of catena-diaqua(2,2′-bipyridyl)-µ-(squarato- O1, O2)-nickel( II) dihydrate

Abstract

The crystal and molecular structure of catena-diaqua(2,2′-bipyridyl)-µ-(squarato- O ¹, O ²)-nickel( II) dihydrate, [{Ni(C ₄O ₄)(C ₁₀H ₈N ₂)(H ₂O) ₂·2H ₂O} _n ][squarate = dihydroxycyclobutenedionate(2–)] has been determined by single-crystal X-ray analysis. The compound crystallizes in the monoclinic system, space group P2 ₁/ c, with a= 11.724(2), b= 7.418(1), c= 19.343(3)Å, and β= 100.16(2)°. The crystal structure contains chains of squarato- O ¹, O ²-bridged Ni ^II metal atoms. These chains are held together by strong hydrogen bonds between the non-co-ordinating oxygen atoms of the squarate anions and the water molecules. Variable-temperature (4.2–290 K) magnetic susceptibilities were determined; the squarato- O ¹, O ² bridge cannot mediate in a significant exchange interaction.