A new synthetic procedure has been developed in Mn cluster chemistry involving reductive aggregation of permanganate (MnO4-) ions in MeOH in the presence of benzoic acid, and the first products from its use are described. The reductive aggregation of (NBu4MnO4)-Mn-n in MeOH/benzoic acid gave the new 4Mn(IV), 8Mn(III) anion [Mn12O12(OMe)(2)(O2CPh)(16)(H2O)2](2-), which was isolated as a mixture of two crystal forms (NBu4n)(2)[Mn12O12(OMe)(2)(-)(O2CPh)(16)(H2O)(2)]center dot 2H(2)O center dot 4CH(2)Cl(2) (1a) and (NBu4n)(2)[Mn12O12(OMe)(2)(O2CPh)(16)(H2O)(2)]center dot(2)H(2)O center dot CH2Cl2 (1b). The anion of 1 contains a central [Mn-4(IV)(mu(3)-O)2(mu-O)(2)(mu-OMe)(2)](6+) unit surrounded by a nonplanar ring of eight Mn-III atoms that are connected to the central Mn-4 unit by eight bridging mu(3)-O(2)(-)ions. This compound is very similar to the well-known [Mn12O12(O2CR)16(H2O)41 complexes (hereafter called "normal Mn-12"), with the main difference being the structure of the central cores. Longer reaction times (similar to 2 weeks) led to isolation of polymeric [Mn(OMe)(O2CPh)21, (2), which contains a linear chain of repeating [Mn-III(mu-O2CPh)(2)(mu-OMe)Mn-III] units. The chains are parallel to each other and interact weakly through :T-stacking between the benzoate rings. When KMnO4 was used instead of (NBu4MnO4)-Mn-n, two types of compounds were obtained, [Mn12O12(O2CPh)(16)(H2O)4] (3), a normal Mn-12 complex, and [Mn4O2(O2CPh)(8)(MeOH)(4)]center dot 2MeOH (4 center dot 2MeOH), a new member of the Mn4 butterfly family. The cyclic voltammogram of 1 exhibits three irreversible processes, two reductions and one oxidation. One-electron reduction of 1 by treatment with 1 equiv of I-in CH2Cl2 gave (NBu4n)[Mn12O12(O2CPh)(16)(H2O)3]center dot 6CH(2)Cl(2) (5 center dot 6CH(2)Cl(2)), a normal Mn-12 complex in a one-electron reduced state. The variable-temperature magnetic properties of 1, 2, and 5 were studied by both direct current (dc) and alternating current (ac) magnetic susceptibility measurements. Variable-temperature dc magnetic susceptibility studies revealed that (i) complex 1 possesses an S = 6 ground state, (ii) complex 2 contains antiferromagnetically coupled chains, and (iii) complex 5 is a typical [Mn-12](-) cluster with an S = 19/2 ground state. Variable-temperature ac susceptibility measurements suggested that 5 and both isomeric forms of 1 (1a,b) are single-molecule magnets (SM). This was confirmed by the observation of hysteresis loops in magnetization vs dc field scans. In addition, la,b, like normal Mn-12 clusters, display both faster and slower relaxing magnetization dynamics that are assigned to the presence of Jahn-Teller isomerism.