The missing link in the series [L 2 M III 2 (µ-O)(µ-MeCO 2 ) 2 ] 2+ (M = Ti, V, Cr, Mn, Fe). Synthesis, crystal structure and magnetism of [L 2 Cr III 2 (µ-O)(µ-MeCO 2 ) 2 ][BPh 4 ] 2

Reaction of pink [L2Cr2(µ-OH)(µ-MeCO2)2][ClO4]3 in MeCN with NEt3 and addition of Na[BPh4] affords deep blue crystals of [L2Cr2(µ-O)(µ-MeCO2)2][BPh4]2(L = 1,4,7-trimethyl-1,4,7-triazacyclononane) the crystal structure of which reveals the presence of the µ-oxo-di(µ-acetato)-dichromium(III) core; weak intramolecular antiferromagnetic exchange coupling between the CrIII ions has been established.