Compressed Jahn-Teller octahedra and spin quintet-triplet switching in coordinatively elastic manganese(III) complexes

Complex assembly preferences and resultant spin state choice Jahn-Teller distortion mode in twelve Mn(III) complexes of varying nuclearity with Schiff base chelate ligands different sizes are compared. Mononuclear Mn(5-F-Sal2323)]OTf (1), [Mn(5-F-Sal2323)]ClO4 (2) [Mn(5-F-Sal2323)]NO3, (3) the 8-carbon R-Sal2323 type show rare axial compression at room temperature also reversible thermal switching from quintet to triplet states on cooling. The prevalence atypical is further probed by single crystal diffraction studies high mononuclear (4)-(7) longer 9-carbon R-Sal2333 series using [Mn(3-OEt-Sal2333)]BF4, (4) [Mn(3,5-diOMe-Sal2333)]BF4·0.5PrOH, (5), [Mn(5-F-Sal2333)]BPh4, (6) Mn(5-NO2-Sal2333)]BPh4, (7) as examples. Ring closure both was observed yielding a ligand 6-membered ring complex [Mn(3-OMe,5-NO2-Sal23336R)]·0.07MeOH·0.93MeCN (8) contrast protonated 5-membered dimeric [Mn2(5-Cl-Sal2323H5R)2](ClO4)2·1.85EtOH·0.33MeCN, (9) type. Finally comparison modes those shorter 7-carbon R-Sal2322 reveal that not favoured smaller chelate. Instead three or cluster rearranged were recovered low yield. structures these [Mn2(5-NO2-Sal23225R)2]·2BuOH, (10), [Mn2(3,5-diBr-Sal23225R)(3,5-diBr-Sal)3]·0.7EtOH·2.61MeCN, (11) [Mn2Na(3-NO2,5-OMe-Sal23225R)]ClO4·0.5MeCN (12) reported compared examples chain ligands.