Differences between the four halide ligands, and discussion remarks on trigonal-bipyramidal complexes, on oxidation states, and on diagonal elements of one-electron energy

Exploring Mechanisms in Ni Terpyridine Catalyzed C–C Cross-Coupling Reactions—A Review

“…Non-innocent ligands [34][35][36][37][38][39] such as tpy contribute strongly to the electron inventory of such nickel complexes, and redox chemistry may often occur at the ligand in addition to the abovementioned oxidation states (0, +I, +II, +III, and +IV). For instance, since tpy is an excellent electron acceptor through its extended π system, a species resulting from the reduction of a nickel(II)-tpy complex can be described in two different resonance forms: as a divalent nickel bound to a radical anionic (tpy) The fundamental studies on the electronic structures of terpyridine nickel complexes have also prompted others to explore details of related pybox complexes (pybox = pyridine-2,6-bisoxazolidine).…”

Discovering More Non‐Innocence: Triazenido versus Triazenyl Radical Ligand Function, and a Comment on [NO2]n as a “Suspect” Ligand

“…In contrast to environmentally and biomedically relevant nitric oxide (NO) [1, 2] which was early recognized as the "simplest case of a suspect (= non-innocent [3] ) ligand" in coordination chemistry [4] with four established charge forms (n =+ ,0,À,2À [5] ) for [NO] n , the textbook nitrogen dioxide [6a] redox system [NO 2 ] n , n =+ ,0,À, has not attracted the same attention as a potential non-innocently behaving ligand in coordination chemistry. In contrast to environmentally and biomedically relevant nitric oxide (NO) [1, 2] which was early recognized as the "simplest case of a suspect (= non-innocent [3] ) ligand" in coordination chemistry [4] with four established charge forms (n =+ ,0,À,2À [5] ) for [NO] n , the textbook nitrogen dioxide [6a] redox system [NO 2 ] n , n =+ ,0,À, has not attracted the same attention as a potential non-innocently behaving ligand in coordination chemistry.…”

Oxidation number: issues of its determination and range

“…It clearly follows from the binding energy E b of the electrons occupying the atomic core orbitals. As for the iron central atom, Based on the above mentioned example it is understandable that the most adequate approach to nitrosyl complexes is that suggested more than 40 years ago by Jörgensen (1966) who proposed to consider nitric oxide a ''non-innocent'' ligand that did not allow the oxidation number of the central atoms to be defined. Applying his idea to [Fe(CN) 5 (NO)] 2-it may be concluded that owing to the strong covalency of the bonds in the (FeNO) 3?…”