Iron(III) and manganese(III) complexes of a pseudocalixarene tetraiminotetraphenol macrocyclic ligand: Structure, magnetism and electrochemistry

The pseudocalixarene tetraiminotetraphenol macrocyclic ligand H4L has been structurally characterized and used to synthesize the complexes [(Fe2L)-L-III(NO3)(2)(H2O)(2)] (1), [(Fe2L)-L-III(Cl)(2)](infinity) (2), [{(Fe2L)-L-III(mu-O)}(2)]center dot 2CH(3)CN center dot H2O (3), [(Mn2L)-L-III(Cl)(2)]center dot 3H(2)O (4) and [(Mn2L)-L-III(OAc)(2)]center dot 5H(2)O (5). The crystal structures of 3 and 4 have been determined. Variable-temperature (2-295 K) magnetic susceptibility measurements have been carried out for 3 and the data have been fitted to the spin Hamiltonian H = -2JS(1).S-2 with J = -45 cm(-1). Cyclic voltammetric measurements carried out for 1 in N,N-dimethylformamide have revealed the presence of two reversible redox couples with E-1/2 = -180 and -280 mV, which coalesced into a single couple with E-1/2 = -220 mV with the addition of excess NaNO3. The two manganese(III) complexes undergo quasi-reversible reduction in methanol at the same potential with E-1/2 = -240 mV. (C) 2014 Elsevier Ltd. All rights reserved.