Iodination of a bifunctional ligand framework restores p53 function by interacting with and inhibiting mutant p53 aggregation.

Oxidation of a series of CrV nitride salen complexes (Cr V NSal R ) with different para-phenolate substituents (R = CF3, tBu, NMe2) was investigated to determine how the locus of oxidation (either metal or ligand) dictates reactivity at the nitride. Para-phenolate substituents were chosen to provide maximum variation in the electron-donating ability of the tetradentate ligand at a site remote from the metal coordination sphere. We show that one-electron oxidation affords CrVI nitrides ([Cr VI NSal R ] + ; R = CF3, tBu) and a localized CrV nitride phenoxyl radical for the more electron-donating NMe2 substituent ([Cr V NSal NMe2 ] •+ ). The facile nitride homocoupling observed for the MnVI analogues was significantly attenuated for the CrVI complexes due to a smaller increase in nitride character in the MN π* orbitals for Cr relative to Mn. Upon oxidation, both the calculated nitride natural population analysis (NPA) charge and energy of molecular orbitals associated with the {CrN} unit change to a lesser extent for the CrV ligand radical derivative ([Cr V NSal NMe2 ] •+ ) in comparison to the CrVI derivatives ([Cr VI NSal R ] + ; R = CF3, tBu). As a result, [Cr V NSal NMe2 ] •+ reacts with B­(C6F5)3, thus exhibiting similar nucleophilic reactivity to the neutral CrV nitride derivatives. In contrast, the CrVI derivatives ([Cr VI NSal R ] + ; R = CF3, tBu) act as electrophiles, displaying facile reactivity with PPh3 and no reaction with B­(C6F5)3. Thus, while oxidation to the ligand radical does not change the reactivity profile, metal-based oxidation to CrVI results in umpolung, a switch from nucleophilic to electrophilic reactivity at the terminal nitride.

The electronic structure of Co and V complexes of a tridentate benzoxazole-containing aminophenol ligand NNOH2 were characterized by both experimental and theoretical methods.