A new pentanuclear bis(triple-helical) manganese complex has been isolated and characterized by X-ray diffraction in two oxidation states: [{Mn-II(mu-bpp)(3)}(2)Mn-2(II)-Mn-III(mu-O)](3+) (1(3+)) and [{Mn-II(mu-bpp)(3)}(2)(MnMn2III)-Mn-II(mu-O)](4+) (1(4+)). The structure consists of a central {Mn-3(mu(3)-O)} core of (Mn2MnIII)-Mn-II (1(3+)) or (MnMn2III)-Mn-II ions (1(4+)) which is connected to two apical Mn-II ions through six bpp(-) ligands. Both cations have a triple-stranded helicate configuration, and a pair of enantiomers is present in each crystal. The redox properties of 1(3+) have been investigated in CH3CN. A series of five distinct and reversible one-electron waves is observed in the -1.0 and +1.50 V potential range assigned to the (Mn4MnIII)-Mn-II/Mn-5(II), (Mn3Mn2III)-Mn-II/(Mn4MnIII,)-Mn-II (Mn2Mn3III)-Mn-II/(Mn3Mn2III)-Mn-II, (MnMn4III)-Mn-II/(Mn2Mn3III)-Mn-II, and Mn-5(III)/(MnMn4III)-Mn-II redox couples. The two first oxidation processes leading to (Mn3Mn2III)-Mn-II (1(4+)) and (Mn2Mn3III)-Mn-II (1(5+)), are related to the oxidation of the Mn-II lions of the central core and the two higher oxidation waves, close in potential, are thus assigned to the oxidation of the two apical Mn-II ions. The 1(4+) and 1(5+) oxidized species and the reduced Mn-4(II) (1(2+)) species are quantitatively generated by bulk electrolyses demonstrating the high stability of the pentanuclear structure in four oxidation states (1(2+) to 1(5+)). The spectroscopic characteristics (X-band electron paramagnetic resonance, EPR, and UV-visible) of these species are also described as well as the magnetic properties of 1(3+) and 1(4+) in solid state. The powder X- and Q-band EPR signature of 1(3+) corresponds to an S = 5/2 spin state characterized by a small zero field splitting parameter (|D| = 0.071 cm(-1)) attributed to the two apical Mn-II ions. At 40 K, the magnetic behavior is consistent for 1(3+). with two apical S = 5/2 {Mn-II(bpp)(3)}(-) and one S = 2 noninteracting Tins (11.75 cm(3) K mol(-1)), and for 1(4+) with three S = 5/2 noninteracting spins (13.125 cm(3) K mol(-1)) suggesting that the {(Mn2MnIII)-Mn-II(mu(3)-O)}(5+) and {(MnMn2III)-Mn-II(mu(3)-O)}(6+) cores behave at low temperature like S = 2 and S = 5/2 spin centers, respectively. The thermal behavior below 40 K highlights the presence of intracomplex magnetic interactions between the two apical spins and thecentral core, which is antiferromagnetic for 1(3+) leading to an S-T = 3 and ferromagnetic for 1(4+) giving thus an S-T = 15/2 ground state.