New MnIIMnIII8 and MnII2MnIII10MnIV2 clusters from the reaction of methyl 2-pyridyl ketone oxime with [Mn12O12(O2CR)16(H2O)4

Abstract

The syntheses, crystal structures and magnetic properties of two mixed-valence Mn clusters [MnIIMnIII8O6(mpko)3(O2CMe)11] (1) and [MnII2MnIII10MnIV2O12(mpko)6(O2CPh)12(H2O)2] (2) are reported. They were obtained from the corresponding reactions in MeCN of [Mn12O12(O2CR)16(H2O)4] (R = Me (3), Ph (4)) with eight equivalents of methyl(pyridine-2-yl)ketone oxime (mpkoH). The cores of 1 and 2 are structurally related: 1 possesses a [Mn9(µ3-O)6]14+ core with an unusual topology comprising a near-planar MnIII-centered MnIII6 hexagon with additional MnII and MnIII ions above and below the plane. Complex 2 possesses a [Mn14(µ4-O)2(µ3-O)10]18+ core that can be described as a dimer of two Mn7 incomplete-cores of 1. It is also a rare example of a Mn cluster containing three Mn oxidation states. Fits of variable-temperature, solid-state dc magnetic susceptibility data collected in a 0.1 T field in the 5.0–300 K range established that 1 and 2 possess ground state spins of S = 3/2 and S = 1, respectively, which were confirmed by ac in-phase susceptibility data.