Influence of neutral auxiliary ligands on crystal structure and magnetic behaviour of new [Mn^II₂Mn^III₂] clusters supported by p-adamantylcalix[4]arene

A series of new manganese complexes of general formula 3(2)-Mn4Xn, displaying a highly-reproducible [(Mn2Mn2III)-Mn-II] cluster core formation, was observed when tetra-p-adamantylcalix[4]arene 3 was used in combination with N,N '-chelating auxiliary ligands, such as bipy (3(2)-Mn-4(bipy)(2), bipy = 2,2 '-bipyridyl) and phen (3(2)-Mn-4(phen)(2), phen = 1,10-phenanthroline), as well as with DMF/H2O solvent molecules (3(2)-Mn-4(dmf)(4), 3(2)-Mn-4(dmf)(2)(H2O)(2)), acting as O-donor coligands, in the crystalline phase. Single-crystal X-ray diffraction revealed that the involvement of auxiliary ligands in coordination with Mn-ions results in the distortion of their coordination sphere and leads to the controlled compression of the {Mn-4}-cluster core of complexes. Moreover, the appearance of adamantyl groups at the upper rim of the macrocyclic backbone of 3 influences the crystalline self-assembly of obtained clusters, providing a preferable "side-to-head" orientation of the cluster molecules within the crystal, leading to the observation of relatively higher {Mn-4}& ctdot;{Mn-4} distances than those revealed for the earlier reported calix[4]arene supported {Mn-4} clusters. All 3(2)-Mn4Xn clusters demonstrated ferromagnetic interactions between the metal atoms within the cluster core independent of the nature of the O-donor or N-donor auxiliary ligands.