Anthony J. Fitzpatrick

Characterization and Reactivity of a Terminal Nickel(III)-Oxygen Adduct

High-valent terminal metal-oxygen adducts are hypothesized to be the potent oxidizing reactants in late transition metal oxidation catalysis. In particular, examples of high-valent terminal nickel-oxygen adducts are scarce, meaning there is a dearth in the understanding of such oxidants. A monoanionic Ni(II)-bicarbonate complex has been found to react in a 1:1 ratio with the one-electron oxidant tris(4-bromophenyl)ammoniumyl hexachloroantimonate, yielding a thermally unstable intermediate in high yield (ca. 95%). Electronic absorption, electronic paramagnetic resonance, and X-ray absorption spectroscopies and density functional theory calculations confirm its description as a low-spin (S = 1/2), square planar Ni(III)-oxygen adduct. This rare example of a high-valent terminal nickel-oxygen complex performs oxidations of organic substrates, including 2,6-di-tert-butylphenol and triphenylphosphine, which are indicative of hydrogen atom abstraction and oxygen atom transfer reactivity, respectively.

Structural and magnetic properties of dinuclear Cu(II) complexes featuring triazolyl-naphthalimide ligands

Abstract Naphthalimide-based ligands have received significant attention for their ability to act as secondary building units for metal containing network structures. The potentially bridging 1,2,4-triazole containing N-(1,2,4-triazolyl)-1,8-naphthalimide (L1) and N-(1,2,4-triazolyl)-4-dimethylamino-1,8-naphthalimide (L2) were prepared, characterized, and complexed with Cu(II) salts. L1 resulted in crystallographically characterized dinuclear complexes, [Cu2(L1)4(NO3)4] and [Cu2(L1)2(OAc)4] when reacted with Cu(NO3)2 and Cu2(OAc)4, respectively. Packing interactions are dominated by π⋯π and anion⋯π interactions and gave rise to structure extension through weak supramolecular interactions. Solid state EPR and magnetism measurements on [Cu2(L1)4(NO3)4] revealed the expected values for a non-magnetically coupled square-based pyramidal dimer structure, while [Cu2(L1)2(OAc)4] showed strong anti-ferromagnetic coupling (JCu–Cu = −185.6 cm−1).