Polyalcohols as ancillary ligands in manganese–oxime chemistry: Syntheses, structures and magnetic properties of a series of trinuclear complexes involving a linear MnII–MnIV–MnII core

Abstract

Using di-2-pyridyl ketonoxime (Hdpko) as an oxime-based ligand in combination with several polyhydric alcohols, viz. ethanediol (H2ed), propanediol (H2pd) and pentaerythritol (H4per), we have synthesized a series of trinuclear complexes involving a linear MnII–MnIV–MnII core, viz. [Mn3(dpko)4(ed)Cl2]·2CH3CN·H2O 1, [Mn3(dpko)4(pd)Cl2]·CH3CN·H2O·0.5H2pd 2 and [Mn3(dpko)4(H2per)Cl2]·4H2O 3, respectively. The trinuclear complexes contain mixed valent MnII–MnIV–MnII units in a linear topology in which MnII and MnIV spin carriers are ferromagnetically coupled. The temperature dependence of the magnetic susceptibility has been fitted with a liner spin trimer model based on the H=−2J{SMn1·SMn2+SMn1′·SMn2} Heisenberg Hamiltonian with J/kB=+1.4(1)K for 1; +4.9(1)K for 2 and +3.7(1)K for 3, leading for the three complexes to an ST=13/2 ground state.