Synthesis and Characterization of [Mn 3 (ppi) 2 ( μ ‐OAc) 4 (H 2 O) 2 ] · 2MeOH — Unusual Structural Properties of a Trinuclear Oxygen‐Rich Manganese Complex

The trinuclear manganese(II) complex [Mn 3 (ppi) 2 ( μ ‐OAc) 4 (H 2 O) 2 ]·2MeOH ( 1 ) (Hppi = 2‐pyridylmethyl‐2‐hydroxyphenylimine) is prepared by dissolving two equivalents of Hppi (from the Schiff Base reaction of aminophenol and pyridine‐2‐carboxaldehyde) in acetonitrile and three equivalents of Mn(OAc) 2 ·4H 2 O in methanol and combining both solutions. The resulting red precipitate was recrystallized to yield red crystals suitable for single crystal X‐ray diffraction. Compound 1 crystallizes in the triclinic space group P1¯ (no. 2), with a = 9.691(2), b = 10.683(2), c = 11.541(2)Å, α = 63.19(3)°, β = 67.47(3)°, γ = 69.11(3)°, V = 960.2(3)Å 3 , and Z = 1. The binding mode of carboxylate in 1 represents a model for a transition state between symmetric syn, syn, anti ‐μ 2 ‐carboxolato‐ O ‐ and syn, anti ‐μ 2 ‐carboxylato‐ O, O′ ‐coordination. Therefore a rare binding mode for the phenomenon of the carboxylate shift is realized. Furthermore the complex is stabilized by a distinctive hydrogen bonding pathway.