Lattice Effects on the Spin‐Crossover Profile of a Mononuclear Manganese(III) Cation

Six solvated salts of a mononuclear manganese(III) complex with a chelating hexadentate Schiff base ligand are reported. One member of the series, [MnL]PF 6 . 0.5 CH 3 OH ( 1 ), shows a rare low‐spin (LS) electronic configuration between 10–300 K. The remaining five salts, [MnL]NO 3 ⋅ C 2 H 5 OH ( 2 ), [MnL]BF 4 ⋅C 2 H 5 OH ( 3 ), [MnL]CF 3 SO 3 ⋅C 2 H 5 OH ( 4 ), [MnL]ClO 4 ⋅C 2 H 5 OH ( 5 ) and [MnL]ClO 4 ⋅0.5 CH 3 CN ( 6 ), all show gradual incomplete spin‐crossover (SCO) behaviour. The structures of all were determined at 100 K, and also at 293 K in the case of 3 – 6 . The LS salt [MnL]PF 6 . 0.5 CH 3 OH is the only member of the series that does not exhibit strong hydrogen bonding. At 100 K two of the four SCO complexes ( 2 and 4 ) assemble into 1D hydrogen‐bonded chains, which weaken or rupture on warming. The remaining SCO complexes 3 , 5 and 6 do not form 1D hydrogen‐bonded chains, but instead exhibit discrete hydrogen bonding between cation/counterion, cation/solvent or counterion/solvent and show no significant change on warming.