The use of di-2-pyridyl ketone oxime, (py)₂CNOH, in manganese carboxylate chemistry has been investigated. Using a variety of synthetic routes complexes [Mn(O₂CPh)₂{(py)₂CNOH}₂]·0.25H₂O (1·0.25H₂O), Mn₄(O₂CPh)₂{(py)₂CO₂}₂{(py)₂CNO}₂Br₂]·MeCN (2·MeCN), [Mn₄(O₂CPh)₂{(py)₂CO₂}₂{(py)₂CNO}₂Cl₂]·2MeCN (3·2MeCN), [Mn₄(O₂CMe)₂{(py)₂CO₂}₂{(py)₂CNO}₂Br₂]·2MeCN (4·2MeCN), [Mn₄(O₂CMe)₂{(py)₂CO₂}₂{(py)₂CNO}₂(NO₃)₂]·MeCN·H₂O (5·MeCN·H₂O) and [Mn₂(O₂CCF₃)₂(hfac)₂{(py)₂CNOH}₂] (6) have been isolated in good yields. Remarkable features of the reactions are the in situ transformation of an amount of (py)₂CNOH to yield the coordination dianion, (py)₂CO₂²⁻, of the gem-diol derivative of di-2-pyridyl ketone in 2–5, the coordination of nitrate ligands in 5 although the starting materials are nitrate-free and the incorporation of CF₃CO₂⁻ ligands in 6 which was prepared from Mn(hfac)₂·3H₂O (hfac⁻ = hexafluoroacetylacetonate). Complexes 2–4 have completely analogous molecular structures. The centrosymmetric tetranuclear molecule contains two Mn^II and two Mn^III six-coordinate ions held together by four µ-oxygen atoms from the two 3.2211 (py)₂CO₂²⁻ ligands to give the unprecedented [Mn^II(µ-OR)Mn^III(µ-OR)₂Mn^III(µ-OR)Mn^II]⁶⁺ core consisting of a planar zig-zag array of the four metal ions. Peripheral ligation is provided by two 2.111 (py)₂CNO⁻, two 2.11 PhCO₂⁻ and two terminal Br⁻ ligands. The overall molecular structure of 5 is very similar to that of 2–4 except for the X⁻ being chelating NO₃⁻. A tentative reaction scheme was proposed that explains the observed oxime transformation and nitrate generation. The CF₃CO₂⁻ ligand is one of the decomposition products of the hfac⁻ ligand. The two Mn^II ions are bridged by two neutral (py)₂CNOH ligands which adopt the 2.0111 coordination mode. A chelating hfac⁻ ligand and a terminal CF₃CO₂⁻ ion complete a distorted octahedral geometry at each metal ion. The CV of complex 3 reveals irreversible reduction and oxidation processes. Variable-temperature magnetic susceptibility studies in the 2–300 K range for the representative tetranuclear clusters 2 and 4 reveal weak antiferromagnetic exchange interactions, leading to non-magnetic S_T = 0 ground states. Best-fit parameters obtained by means of the program CLUMAG and applying the appropriate Hamiltonian are J_{Mn(II)⋯Mn((III)} = −1.7 (2), −1.5 (4) cm⁻¹ and J_{Mn(III)⋯Mn(III)} = −3.0 (2, 4) cm⁻¹.