The reaction of Mn(O(2)CPh)(2) . 2H(2)O and PhCO(2)H in EtOH/MeCN with NBu(4)(n)MnO(4) gives (NBu(4)(n))[Mn4O2(O(2)CPh)(9)-(H2O)] (4) in high yield (85-95%). Complex 4 crystallizes in monoclinic space group P2(1)/c with the following unit cell parameters at -129 degrees C : a = 17.394(3) Angstrom, b = 19.040(3) Angstrom, c = 25.660(5) Angstrom, beta = 103.51(1)degrees, V = 8262.7 Angstrom(3), Z = 4; the structure was refined on F to R (R(w)) = 9.11% (9.26%) using 4590 unique reflections with F > 2.33 sigma(F). The anion of 4 consists of a [Mn-4(mu(3)-O)(2)](8+) core with a "butterfly" disposition of four Mn-III atoms. In addition to seven bridging PhCO(2)(-) groups, there is a chelating PhCO(2)(-) group at one "wingtip" Mn atom and terminal PhCO(2)(-) and H2O groups at the other. Complex 4 is an excellent steppingstone to other [Mn4O2]-containing species. Treatment of 4 with 2,2-diethylmalonate (2 equiv) leads to isolation of (NBu(4)(n))(2)[Mn8O4(O(2)CPh)(12)(Et(2)mal)(2)(H2O)(2)] (5) in 45% yield after recrystallization. Complex 5 is mixed-valent (2Mn(II),6Mn(III)) and contains an [Mn8O4](14+) core that consists of two [Mn4O2](7+) (Mn-II,3Mn(III)) butterfly units linked together by one of the mu(3)-O2- ions in each unit bridging to one of the body Mn atoms in the other unit, and thus converting to mu(4)-O2- modes. The Mn-II ions are in wingtip positions. The Et(2)mal(2-) groups each bridge two wingtip Mn atoms from different butterfly units, providing additional linkage between the halves of the molecule.