  The preparations, X-ray structures, and detailed physical characterizations
are presented for two new mixed-valence tetranuclear manganese complexes that
function as single-molecule magnets (SMM's): [Mn4(hmp)6Br2(H2O)2]Br2.4H2O and
[Mn4(6-me-hmp)6Cl4].4H2O, where hmp- is the anion of 2-hydroxymethylpyridine
and 6-me-hmp- is the anion of 6-methyl-2-hydroxymethylpyridine.
