A symmetry breaking spin transition in a Mn(III) complex is reported with three structural phases, a high symmetry high temperature S = 2 phase, an intermediate S = 1/S = 2 ordered phase and an aperiodic low temperature phase with S = 1 cations. The aperiodicity is interpreted as resulting from long-range ordering of the NTf₂ ⁻ anions.

High‐valent terminal metal–oxygen adducts are hypothesized to be the potent oxidizing reactants in late transition metal oxidation catalysis. In particular, examples of high‐valent terminal nickel–oxygen adducts are scarce, meaning there is a dearth in the understanding of such oxidants. A monoanionic Ni^II‐bicarbonate complex has been found to react in a 1:1 ratio with the one‐electron oxidant tris(4‐bromophenyl)ammoniumyl hexachloroantimonate, yielding a thermally unstable intermediate in high yield (ca. 95 %). Electronic absorption, electronic paramagnetic resonance, and X‐ray absorption spectroscopies and density functional theory calculations confirm its description as a low‐spin (S=1/2), square planar Ni^III–oxygen adduct. This rare example of a high‐valent terminal nickel–oxygen complex performs oxidations of organic substrates, including 2,6‐di‐tert‐butylphenol and triphenylphosphine, which are indicative of hydrogen atom abstraction and oxygen atom transfer reactivity, respectively.

Single ion magnet behaviour is reported for a mononuclear Mn(III) ion with tridentate Schiff-base ligands which exhibits a tetragonal Jahn–Teller elongation along the N_amine–Mn–N_amine axis and crystallises with two crystallographically distinct Mn(III) cations (unit A and unit B). While magnetic measurements show a large and negative axial zero-field splitting (D = −4.73 cm⁻¹), HF-EPR reveal two distinct large axial Ds (D = −4.60 cm⁻¹ for unit A and D = −4.18 cm⁻¹ for unit B), thus resulting in the largest D known to date for a Mn(III) single ion magnet. AC magnetic measurements at 2000 Oe allowed determination of the energy barrier for spin reversal (10.19 K) and spin reversal relaxation time (1.476 × 10⁻⁶ s) for the Mn(III) ion. Computational studies were used to characterise the electronic structure and substantiate the zero field splitting in the Mn(III) complex.

Two new paramagnetic ionic liquids (ILs) comprising a mononuclear iron( iii ) or manganese( iii ) complex cation, charge balanced by a dicyanamide anion are reported which show a range of spin states including spin crossover.