Versatile Reactivity of Mn Complexes in Reactions with N-Donor Heterocycles: Metamorphosis of Labile Homometallic Pivalates vs. Assembling of Endurable Heterometallic Acetates.

Reaction of 2,2'-bipyridine (2,2'-bipy) or 1,10-phenantroline (phen) with [Mn(Piv)(EtOH)] led to the formation of binuclear complexes [Mn(Piv)L] (L = 2,2'-bipy (), phen (); Piv is the anion of pivalic acid). Oxidation of or by air oxygen resulted in the formation of tetranuclear Mn complexes [MnO(Piv)L] (L = 2,2'-bipy (), phen ()). The hexanuclear complex [Mn(OH)(Piv)(pym)] () was formed in the reaction of [Mn(Piv)(EtOH)] with pyrimidine (pym), while oxidation of produced the coordination polymer [MnO(Piv)(pym)] (). Use of pyrazine (pz) instead of pyrimidine led to the 2D-coordination polymer [Mn(OH)(Piv)(µ-pz)] (). Interaction of [Mn(Piv)(EtOH)] with FeCl resulted in the formation of the hexanuclear complex [MnFeO(Piv)(MeCN)(HPiv)] (). The reactions of [MnFeO(OAc)(HO)] with 4,4'-bipyridine (4,4'-bipy) or -1,2-(4-pyridyl)ethylene (bpe) led to the formation of 1D-polymers [MnFeO(OAc)L]·2DMF, where L = 4,4'-bipy (·2DMF), bpe (·2DMF) and [MnFeO(OAc)(bpe)(DMF)]·3.5DMF (·3.5DMF). All complexes were characterized by single-crystal X-ray diffraction. Desolvation of ·3.5DMF led to a collapse of the porous crystal lattice that was confirmed by PXRD and N sorption measurements, while alcohol adsorption led to porous structure restoration. Weak antiferromagnetic exchange was found in the case of binuclear Mn complexes ( = -1.03 cm for and ). According to magnetic data analysis ( = -(2.69 ÷ 0.42) cm) and DFT calculations ( = -(6.9 ÷ 0.9) cm) weak antiferromagnetic coupling between Mn ions also occurred in the tetranuclear {Mn(OH)(Piv)} unit of the 2D polymer . In contrast, strong antiferromagnetic coupling was found in oxo-bridged trinuclear fragment {MnFeO(OAc)} in ·3.5DMF ( = -57.8 cm, = -20.12 cm).