The syntheses, structures, and magnetochemical properties are reported for five new Mn clusters: [MnO(OPPh)(mpko)](ClO) (1), [MnO(OPPh)(ppko)](ClO) (2) [MnO(OMe)(OPPh)(mpko)](ClO) (3), [MnMnO(OCMe)(OPPh)(mpko)(HO)] (4), and [MnMnO(mpko)(HO)(ClO)](ClO) (5), where mpko (or ppko) is the anion of methyl (or phenyl) 2-pyridyl ketone oxime. 1 was obtained by carboxylate substitution on [MnO(OCMe)(mpko)](ClO) by treatment with diphenylphosphinic acid (PhPOH). The comproportionation reaction between Mn(ClO) and NBuMnO in the presence of PhPOH and ppkoH in EtOH, or mpkoH in MeOH, led to 2 and 3, respectively. 4 was obtained as was 3, but with phenylphosphonic acid (PhPOH) instead of PhPOH. 5 was obtained by aerial oxidation of Mn(ClO) in the presence of mpkoH. 1 and 2 contain a triangular Mn core, 3 comprises the fusion of two Mn units of 1 by MeO bridges, and 4 has a cagelike structure. 5 is similar to 1 in possessing a triangular core. Variable-temperature, solid-state direct-current (dc) and alternating-current (ac) magnetic data were collected on 1-5: 1 and 2 exhibit ferromagnetic Mn····Mn exchange interactions, S = 6 ground states, and are new single-molecule magnets (SMMs). 3-5 possess S = 4, /, and / ground states, respectively, from dominant antiferromagnetic interactions. Fits of dc magnetization data in the 1.8-10.0 K and 10-70 kG ranges gave D and g values of: -0.29(2) cm and 1.94(1) for 1, -0.38(2) cm and 1.99(1) for 2, -0.29(2) cm and 1.96(1) for 3, -1.26(4) cm and 1.99(2) for 4, -1.41(4) cm and 1.98(2) for 5, where D is the axial zero-field splitting parameter.

The syntheses, crystal structures and magnetic properties are reported of two new and unusual mixed-valence Mn clusters [Mn II 4 Mn IV O(mpko) 5 (MeO-hmp)(mpko-hmp)(H 2 O)](ClO 4) 3 (1) and [Mn II 4 Mn IV O(ppko) 5 (MeO-hmp)(ppko-hmp)(H 2 O)](ClO 4) 3 (2). They were obtained from the reaction of mpkoH or ppkoH and hmpH with Mn(ClO 4) 2 in the presence of NaOMe, where mpkoH is methyl(pyridin-2-yl)ketone oxime, ppkoH is phenyl(pyridin-2-yl)ketone oxime, and hmpH is 2-(hydroxymethyl)pyridine. Complex 1 possesses a distorted Mn II 4 cubane core attached to an external Mn IV by the O 2ion. The peripheral ligation includes two unprecedented hemiacetal ligands formed in situ from the reaction of hmpH with MeOH or mpkoH/ppkoH. Solid-state dc and ac magnetic susceptibility measurements established that both 1 and 2 possess an S = 7 / 2 ground state, which was confirmed by ac in-phase susceptibility data. Simulations of the χ M T vs T data established the presence of dominant antiferromagnetic exchange interactions, rationalizing the observed ground state.