摘要
To carry and deliver nitric oxide with a controlled redox state and rate is crucial for its pharmaceutical/medicinal applications. In this study, the capability of cationic {Fe(NO) 2 } 9 dinitrosyl iron complexes (DNICs) [( R DDB)Fe(NO) 2 ] + (R = Me, Et, Iso; R DDB = N,N'-bis(2,6-dialkylphenyl)-1,4-diaza-2,3-dimethyl-1,3-butadiene) carrying nearly unperturbed nitric oxide radical to form [( R DDB)Fe(NO) 2 (•NO)] + was demonstrated and characterized by IR UV-vis, EPR, NMR, and single-crystal X-ray diffractions. The unique triplet ground state of [( R DDB)Fe(NO) 2 (•NO)] + results from the ferromagnetic coupling between two strictly orthogonal orbitals, one from Fe d 2 2 and the other a π ∗ op orbital of a unique bent axial NO ligand, which is responsible for the growth of a half-field transition (ΔM S = 2) from 70 to 4 K in variable-temperature EPR measurements. Consistent with the NO radical character of coordinated axial NO ligand in complex [( Me DDB)Fe(NO) 2 (•NO)] + , the simple addition of MeCN/H20 into CH 2 Cl 2 solution of complexes [( R DDB)Fe(NO) 2 (•NO)] + at 25 °C released NO as a neutral radical, as demonstrated by the formation of [S 5 Fe(NO) 2 ]-from [S 5 Fe(μ-S) 2 FeS 5 ] 2- .