MnIII zero-field splitting parameters and weak exchange interactions in a cyanide-bridged {MnIII–IrIII–MnIII} cluster

The reaction of [MnIII(5-Brsalen)(MeOH)](ClO4) (5-Brsalen2 − = N,N′-ethylenebis(5-bromosalicylidene-iminate)) with [IrIII(CN)6]3 − yields a trinuclear, cyanide-bridged MnIII–IrIII–MnIII cluster which is a member of an isostructural series of MnIII–MIII–MnIII clusters. The presence of the large, diamagnetic [IrIII(CN)6]3 − bridging unit facilitates a precise determination of the MnIII zero-field splitting (zfs) parameters by the combined use of inelastic neutron scattering, high-field, high-frequency EPR spectroscopy and magnetic measurements. The single-ion axial (D) and rhombic (E) zfs parameters are found to be D = − 3.72(5) cm− 1 and |E| = 0.21(1) cm− 1. The experimental data are consistent with a small, antiferromagnetic exchange interaction between the two MnIII ions.

Graphical abstractThe zero-field splitting parameters of Mn(III) in a novel MnIII–IrIII(CN6)–MnIII trinuclear complex are determined by inelastic neutron scattering.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The first molecular polynuclear complex incorporating the [IrIII(CN)6]3 − is reported. ► INS and HF-EPR spectroscopy determine the Mn(III) zero-field splitting parameters. ► An upper limit for the magnitude of the Mn(III)-Mn(III) interaction is determined.