Crystal structure of high-spin (S= 5/2) manganese(II) 2,3,7,8,12,13,17,18-octakis(ethylsulfanyl)-5,10,15,20-tetraazaporphyrinate

Abstract

The crystal structure of [Mn(oetpz)][oetpz = 2,3,7,8,12,13,17,18-octakis(ethylsulfanyl)-5,10,15,20-tetraazaporphyrinate] has been determined by single-crystal X-ray study and refined to an R value of 0.044 (R′= 0.050). The porphyrazine ring shows a pseudo-S₄ ruffling. The manganese atom co-ordinates within the central cavity of the macrocyclic ligand to a nearly planar array of pyrrolic nitrogen atoms, mean Mn–N_p 1.927(6)Å. The intermolecular packing is reminiscent of a herringbone arrangement. Each molecule is linked to two neighbours related to it through inversion centres resulting in pseudo-octahedral metal environment with axial Mn ⋯ S bonds of 2.869(2) and 2.916(2)Å. Magnetic and EPR data are consistent with a weakly antiferromagnetically coupled high-spin (S= 5/2) manganese(II) system. Density functional calculations indicated that such a ground spin state is unlikely for the isolated molecule. It is supposed that intermolecular interactions, mainly the axial Mn ⋯ S weak bonds, play a key role in determining the ground spin state experimentally found.