A tetranuclear manganese cluster with a star-shaped Mn4O6 core motif: Directed synthesis using a mononuclear precursor complex

Abstract

The tetranuclear manganese(II) complex [Mn4(ppi)6](BPh4)2 (2) (Hppi = 2-pyridylmethyl-2-hydroxy-phenylimine) is prepared by using the precursor complex [Mn(ppi)2]·H2O (1). Based on UV/Vis- and IR-spectroscopy data in combination with mass spectrometry it has been concluded that 1 is a mononuclear neutral MnII complex, in which two ppi ligands chelate the manganese atom. Compound 2 crystallizes in the tri-clinic space group P1 (no. 2), with a = 17.500(3), b = 17.955(4), c = 19.101(4) Å, α = 113.79(3)°, β = 111.33(3)°, γ = 93.91(3)°, V = 4950(2) Å3 and Z = 2. In the tetranuclear [Mn4(ppi)6]2+ complex cation Mn(1), Mn(2), and Mn(3) are equivalently coordinated by two deprotonated Hppi ligands leading to a N4O2 donor set. The environment of the central Mn(4) is formed by coordination of three [Mn(ppi)2] fragments resulting in a phenoxo bridged star-shaped Mn4O6 core motif. The average distance of directly adjacent manganese ions is 3.310 Å, whereas the average distance of Mn(1), Mn(2), and Mn(3) among each other is 5.732 Å.