Understanding the metal ion properties that favor O-H bond formation versus cleavage should facilitate the development of catalysts tailored to promote a specific reaction, e.g., C-H activation or H2O oxidation. The first step in H2O oxidation involves the endothermic cleavage of a strong O-H bond (BDFE = 122.7 kcal/mol), promoted by binding the H2O to a metal ion, and by coupling electron transfer to proton transfer (PCET). This study focuses on details regarding how a metal ions electronic structure and ligand environment can tune the energetics of M(HO-H) bond cleavage. The synthesis and characterization of an Fe(II)-H2O complex, 1, that undergoes PCET in H2O to afford a rare example of a monomeric Fe(III)-OH, 7, is described. High-spin 7 is also reproducibly generated via the addition of H2O to {[Fe-III(OMe2N4(tren))]2-(mu-O)}(2+) (8). The OH bond BDFE of Fe(II)-H2O (1) (68.6 kcal/mol) is calculated using linear fits to its Pourbaix diagram and shown to be 54.1 kcal/mol less than that of H2O and 10.9 kcal/mol less than that of [Fe(II)-(H2O)6](2+). The OH bond of 1 is noticeably weaker than the majority of reported Mn+(HxO-H) (M = Mn, Fe; n+ = 2+, 3+; x = 0, 1) complexes. Consistent with their relative BDFEs, Fe(II)-H2O (1) is found to donate a H atom to TEMPO, whereas the majority of previously reported Mn+O(H) complexes, including [Mn-III(SMe2N4(tren))-(OH)](+) (2), have been shown to abstract H atoms from TEMPOH. Factors responsible for the weaker O-H bond of 1, such as differences in the electron-donating properties of the ligand, metal ion Lewis acidity, and electronic structure, are discussed.