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) (1), Mn2(salen)2(C6H5PO3H) (2) and Mn2(salen)2(C6H5PHO2) (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.