Mixed-valent diruthenium diphosphonate containing zigzag chain structure of {Ru2(hedp)2(SCN)}n4n−

This paper reports the crystal structure and magnetism properties of a novel mixed-valent diruthenium(II,III) complex, [C(NH2)3]4[Ru2(hedp)2(SCN)]·4H2O (1), where hedp represents 1-hydroxyethylidenediphosphonate. It shows a zigzag chain structure in which the paddlewheel diruthenium(II,III) dimers of Ru2(hedp)23 − linked by SCN− bridges. The chains are stacked along the [011] direction with strong intra- and interchain hydrogen bonds. Magnetic studies show that significant antiferromagnetic exchanges are mediated between the [Ru2(hedp)2]3 − (S = 3/2) units through thiocyanate ion bridges. Structural analysis proves that the Rusingle bondRu bond weakening ability is H2O < Br− < Cl− < μ-NCS− < μ-NC− < μ-SCN−.