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

Abstract

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.