The O–P–O bridged Mn2(salen)2 chains showing coexistence of single chain magnet and metamagnet behaviour

Three new chain compounds in which the Mn2(salen)2 dimers are bridged by O–P–O units are reported, namely, [Mn2(salen)2(C6H9PO3H)](ClO4) (1), [Mn2(salen)2(C6H5PO3H)](ClO4) (2) and [Mn2(salen)2(C6H5PHO2)](ClO4) (3). The phosphonate or phosphinate ligands adopt a syn–anti bidentate bridging mode in 1, while a syn–syn bidentate bridging mode in 2 and 3, thus leading to a difference in the Mn–O⋯O–Mn torsion angle over the O–P–O bridge. Compound 1 shows a paramagnetic behavior with dominant antiferromagnetic interactions. In compounds 2 and 3, the antiferromagnetic interactions through the O–P–O bridges are considerably stronger than those in 1. They display coexistence of single chain magnet (SCM) behaviour with a spin canted structure and metamagnetism at low temperature. The results demonstrate that the magnetic dynamics of the O–P–O bridged Mn2(salen)2 chains may be modulated by selecting suitable phosphonate or phosphinate ligands.