Nickel(II) meso-Hydroxyporphyrin Complexes Revisited: Palladium-Catalysed Synthesis, Electronic Structures of Derived Oxy Radicals, and Oxidative Coupling to a Dioxoporphodimethene Dyad

作者：Esdaile Louisa J; Rintoul Llew; Goh Mean See; Merahi Khalissa; Parizel Nathalie; Wellard R Mark; Choua Sylvie; Arnold Dennis P^*

来源：Chemistry - A European Journal, 2016, 22(10): 3430-3446.

DOI：10.1002/chem.201504252

• density functional calculations
• EPR spectroscopy
• NMR spectroscopy
• porphyrinoids
• radicals

We report the synthesis and characterisation of new examples of meso-hydroxynickel(II) porphyrins with 5,15-diphenyl and 10-phenyl-5,15-diphenyl/diaryl substitution. The OH group was introduced by using carbonate or hydroxide as nucleophile by using palladium/phosphine catalysis. The NiPor-OHs exist in solution in equilibrium with the corresponding oxy radicals NiPor-O-.. The 15-phenyl group stabilises the radicals, so that the (HNMR)-H-1 spectra of {NiPor-OH} are extremely broad due to chemical exchange with the paramagnetic species. The radical concentration for the diphenylporphyrin analogue is only 1%, and its NMR line-broadening was able to be studied by variable-temperature NMR spectroscopy. The EPR signals of NiPor-O-. are consistent with somewhat delocalised porphyrinyloxy radicals, and the spin distributions calculated by using density functional theory match the EPR and NMR spectroscopic observations. Nickel(II) meso-hydroxy-10,20-diphenylporphyrin was oxidatively coupled to a dioxo-terminated porphodimethene dyad, the strongly red-shifted electronic spectrum of which was successfully modelled by using time-dependent DFT calculations.

• 出版日期2016-3-1