Dynamic motion and various reaction paths of cobaloxime complexes in crystalline-state photoreaction

Abstract

The various alkyl groups bonded to the cobalt atom in (alkyl)(base)cobaloxime complex crystals are isomerized on exposure to visible light without degradation of the single crystal form. The solid-state reactions keeping the single crystal form were called crystalline-state reactions and the reaction mechanisms were explained with the concept of reaction cavity for the alkyl group. Changing the axial base ligands, a variety of crystalline-state reactions were examined not only by X-rays but also by neutron diffraction. The various reaction paths were made clear from the structures of initial, intermediate and final stages of the reactions. Moreover, the reaction rate was proved to have a positive relation with the volume of reaction cavity in each reaction. Not only various isomerizations but also unusual racemic-to-chiral transformations and a chirality inversion were also observed and the mechanisms were clearly explained and the shape of the reaction cavity made clear the mechanism. Two promising methods to observe the photoreaction with retention of the single crystal form, mixed crystal formation and bulky group insertion, are proposed and several successful results are shown.

Metal-Involving Synthesis and Reactions of Oximes

“…When the catalytic system was replaced with [Ir 2 Cl 2 (cod) 2 ]/ Ba(OH) 2 /54 (Scheme 25), the regioselectivity of the reaction between 50 (R 1 /R 2 = Ph/H) and 51 (Ar = Ph) shifted, and PhC(H)NOC(Ph)HC(H)CH 2 (53) was isolated from the reaction mixture in 85% yield and 42% ee of the (S)enantiomer. 177 The iridium(I)-catalyzed O-allylation of oximes was extended to a series of allylphosphates.…”

“…Ligation of oximes to metal centers, giving oxime and oximato metal complexes, has been under intense investigation ever since (for reviews on coordination chemistry of oximes within the past decade see refs and ). The discovery of useful catalytic − and magnetic properties − of oxime metal species and oxime-based clathrochelates − further elevated the impact of these studies. It is worth specifically emphasizing the crucial role played by vic -dioximato cobalt complexes in the elucidation of activity of vitamin B 12 . , …”

Thermal and photochemical control of nitro–nitrito linkage isomerism in single-crystals of [Ni(medpt)(NO2)(η2-ONO)]

“…18 In the context of 1, the reaction cavity is defined as the region encapsulating a photoactive nitrite group. The cavity volume can be determined by removing the nitrite ligand in question from the crystal structure and conducting a void space calculation on the remaining structure, using the CCDC software package Mercury.…”

The Reasons for Different Kinetics of the Norrish-Yang Reaction in Crystals. Structural and Spectroscopic Studies

“…According to the topochemical postulate, a photochemical reaction proceeds in crystals when there is the possibility of breaking old bonds and forming new ones. Such a reaction is easier when the required atomic shifts are small and a reaction cavity − does not significantly change its geometry. , However, when there is free space close to the reacting molecular fragments, the reaction can occur, although the necessary shifts and changes are significant. Moreover, the existence of such a free space can cause a crystal lattice to better accommodate a strain caused by the appearance of product molecules.…”