Photochemical and photophysical behavior of trans-diisothiocyanatobis(ethylenediamine)chromium(III)

Metal centered ligand field excited states: Their roles in the design and performance of transition metal based photochemical molecular devices

“…Under these conditions, P (514 nm)/˚P(436 nm) = 0.60 [56]. Likewise, the fraction of the photoreaction attenuated by selective doublet state quenchers was also dependent on ex [55][56][57][58]. These observations suggest that the higher energy irradiation populates quartet Franck-Condon states at energies above the quartet/doublet crossing point such that quartet to doublet ISC effectively competes with vibrational cooling.…”

“…For certain Cr(III) complexes, however, it was found that 2 E g phosphorescence quantum yields are dependent on excitation wavelength ( ex ) [55][56][57][58]. An example is the Cr(NH 3 ) 6 3+ cation where the phosphorescence quantum yields (298 K) were determined for excitation at 514 nm and 436 nm, both wavelengths corresponding to excitation into the first ligand field band.…”

Hydroxylation of N-Heterocycle Ligands Observed in Two Unusual Mixed-Valence CuI/CuII Complexes

“…[6] More generally, nitro-aldol adducts provide ready access to non-natural 3-amino-2-hydroxy acids and 1,3diamino-2-hydroxy units, which are substructures of medicinally important compounds. [7,8] One of us previously demonstrated that the Henry reaction is highly accelerated by pressure. [9] However, to our knowledge, no attempts have ever been made to perform a diastereoselective nitro-aldol reaction without a catalyst.…”

“…Gillard mechanism for the hydroxylation of [L 2 M(phen)] 2 . PB pseudo-base.was questioned [4±8] because of to the lack of structural evidence [6,7] for the CH intermediate. [8] However, if the proposed covalent hydrates of phen and bpy could be isolated as hydroxylated products, they would be novel heterocyclic ligands capable of chelating and bridging ligation for the synthesis of polynuclear metal complexes.…”

Hydroxylation of N-Heterocycle Ligands Observed in Two Unusual Mixed-Valence CuI/CuII Complexes

“…To rationalize the anomalous properties of complexes such as [M(bpy) 3 ] n and [M(phen) 3 ] n , Gillard borrowed the idea of ™covalent hydrates∫ from the organic literature and proposed an interesting mechanism, [3] the core of which is nucleophilic attack of a hydroxide ion on a coordinated heterocyclic ligand to form a covalent hydrate (CH); this may react further by intramolecular shift of OH À or H 2 O onto the metal before the formation of the final products (Scheme 1). PB pseudo-base.was questioned [4±8] because of to the lack of structural evidence [6,7] for the CH intermediate. Gillard mechanism for the hydroxylation of [L 2 M(phen)] 2 .…”