Compressed Jahn-Teller octahedra and spin quintet-triplet switching in coordinatively elastic manganese(III) complexes. (1st November 2021)

• Record Type: Journal Article
• Authors: Sundaresan, Sriram; Kühne, Irina A.; Evesson, Colin; Harris, Michelle M.; Fitzpatrick, Anthony J.; Ahmed, Ahmed; Müller-Bunz, Helge; Morgan, Grace G.
• Is Part Of: Polyhedron. Volume 208(2021)
• Publication Date: 2021-11-01
• Subjects: Manganese -- Schiff base -- Spin crossover -- Spin quintet -- Spin triplet -- Ligand rearrangement -- Ring closure -- Dimer; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2021.115386
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: Abstract: Complex assembly preferences and resultant spin state choice and Jahn-Teller distortion mode in twelve Mn(III) complexes of varying nuclearity with Schiff base chelate ligands of different sizes are compared. Mononuclear complexes Mn(5-F-Sal2 323)]OTf (1 ), [Mn(5-F-Sal2 323)]ClO4 (2 ) and [Mn(5-F-Sal2 323)]NO3, (3 ) with the 8-carbon R-Sal2 323 chelate type show rare axial compression at room temperature and complexes (2 ) and (3 ) also show reversible thermal spin state switching from spin quintet to triplet states on cooling. The prevalence of atypical axial compression is further probed by single crystal diffraction studies on high spin mononuclear complexes (4 )-(7 ) with the longer 9-carbon R-Sal2 333 chelate series using [Mn(3-OEt-Sal2 333)]BF4, (4 ) [Mn(3, 5-diOMe-Sal2 333)]BF4 ·0.5PrOH, (5 ), [Mn(5-F-Sal2 333)]BPh4, (6 ) and Mn(5-NO2 -Sal2 333)]BPh4, (7 ) as examples. Ring closure of both the 8-carbon R-Sal2 323 and longer 9-carbon R-Sal2 333 ligands was also observed yielding a ligand with a 6-membered ring in the mononuclear complex [Mn(3-OMe, 5-NO2 -Sal2 333 6R )]·0.07MeOH·0.93MeCN (8 ) in contrast to a protonated 5-membered ring in the dimeric complex [Mn2 (5-Cl-Sal2 323 H5R )2 ](ClO4 )2 ·1.85EtOH·0.33MeCN, (9 ) with the R-Sal2 323 chelate type. Finally comparison of the assembly modes of Mn(III) complexes of the 8-carbon R-Sal2 323 and 9-carbon R-Sal2 333 series with those of the shorter 7-carbon R-Sal2 322 ligand series reveal that the mononuclear assembly mode is not favoured with the smaller chelate. Instead three dimeric or cluster complexes with rearranged ligands were recovered in low yield. The structures of these complexes [Mn2 (5-NO2 -Sal2 322 5R )2 ]·2BuOH, (10 ), [Mn2 (3, 5-diBr-Sal2 322 5R )(3, 5-diBr-Sal)3 ]·0.7EtOH·2.61MeCN, (11 ) and [Mn2 Na(3-NO2, 5-OMe-Sal2 322 5R )]ClO4 ·0.5MeCN (12 ) are reported and compared with examples with the longer chain R-Sal2 323 and R-Sal2 333 chelate ligands.