A new end-on azido bridged MnIII single-chain magnet and its dimeric single molecule magnet polymorph. Synthesis, structure and magnetic properties of [Mn(5-Clsalpn)N3]n and phenoxo bridged [Mn(5-Clsalpn)N3]2

Abstract

An end-on azido bridged Mn^III coordination chain polymer [Mn(5-Clsalpn)N₃]_n (complex 1) and its dimeric polymorph, [Mn(5-Clsalpn)N₃]₂ (complex 2), where 5-Clsalpn is N,N′-bis(5-chlorosalicylidene)-1,3-diaminopropane, were prepared. Complex 1, which is obtained as two concomitant polymorphs (1a and 1b) with nearly identical molecular structures but different crystal packing, has μ-1,1(end-on) azido bridges. This single atom bridge is unsymmetrical and leads to a −1 cm⁻¹ antiferromagnetic interaction among Mn^III centers of the one-dimensional coordination polymer. Mn^III anisotropy is manifested through Jahn–Teller elongation along the N(azido)–Mn–N(azido) axis, and results in single-chain magnet behavior. The phenoxo-bridged dimer (complex 2) has terminal azido ligands and a ferromagnetic interaction is mediated by the unsymmetrical bis-phenoxo bridge. Mn^III anisotropy is manifested through Jahn–Teller elongation along an N–Mn–O axis, and results in single molecule magnet behavior. The dimers are organized into a two-dimensional network structure via Cl⋯Cl and Cl⋯H-phenyl interactions which are also ferromagnetic.