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 32-Mn4Xn, displaying a highly-reproducible [MnII2MnIII2] 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 (32-Mn4(bipy)2, bipy = 2,2′-bipyridyl) and phen (32-Mn4(phen)2, phen = 1,10-phenanthroline), as well as with DMF/H2O solvent molecules (32-Mn4(dmf)4, 32-Mn4(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 {Mn4}-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 {Mn4}⋯{Mn4} distances than those revealed for the earlier reported calix[4]arene supported {Mn4} clusters. All 32-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.