Ferrocene-MnII π-interaction in the complex [Fc2Bpz2PhMn(THF)Cl]

The ferrocene-based bis(pyrazol-1-yl) borate ligands [Fc(2)Bpz(2)] ([2]) and [Fc(2)Bpz(2)(Ph)] ([2(Ph)]) have been prepared (Fc: ferrocenyl; pz: pyrazol-1-yl; pz(Ph): 3-phenylpyrazol-1-yl). Treatment of [2] and [2Ph] with MnCl2 in THF leads to the complexes [Fc(2)Bpz(2)Mn(THF)(mu-Cl)(2)Mn(THF)pz(2)BFc(2)] (3) and [Fc(2)Bpz(2)(Ph)Mn(THF)Cl] (3(Ph)), respectively, which have been structurally characterized by X-ray crystallography. While there is clearly no ferrocene-Mn-II pi-coordination in the solid-state structure of 3, short Mn-II-C5H4 contacts are established in 3(Ph) (shortest Mn-C distances: 2.780(2) angstrom, 2.872(2) angstrom). The cyclic voltammograms of K[2(Ph)] and 3(Ph) show the first ferrocene/ferricinium redox wave of 3(Ph) to be shifted anodically by 0.60 V compared with the first Fe-II/Fe-III transition of K[2(Ph)]. (C) 2008 Elsevier B.V. All rights reserved.