Spectroscopic and electrochemical characterization of an aqua ligand exchange and oxidatively induced deprotonation in diiron complexes.

Reaction of the unsymmetrical phenol ligand 2-((bis(2-pyridylmethyl)amino)methyl)-6-(((2-pyridylmethyl)benzylamino)methyl)-4-methylphenol (HL-Bn) or its 2,6-dichlorobenzyl analogue (HL-BnCl2) with Fe(H2O)6(ClO4)2 in the presence of disodium m-phenylenedipropionate (Na2(mpdp)) followed by exposure to atmosphere affords the diiron(II,III) complexes [Fe2(L-Bn)(mpdp)(H2O)](ClO4)2 and [Fe2(L-BnCl2)(mpdp)(CH3OH)](ClO4)2, respectively. The latter complex has been characterized by X-ray crystallography. It crystallizes in the monoclinic system, space group P21/n, with a = 13.3095(14) A, b = 20.1073(19) A, c = 19.4997(19) A, α = 90°, β = 94.471(2)°, γ = 90°, V = 5202.6(9) A3, and Z = 4. The structure of the compound is very similar to that of [Fe2(L-Bn)(mpdp)(H2O)](BPh4)2 determined earlier, except for the replacement of a water by a methanol on the ferrous site. Magnetic measurements of [Fe2(L-Bn)(mpdp)(H2O)](BPh4)2 reveal that the two high-spin Fe ions are moderately antiferromagnetically coupled (J = −3.2(2) cm...