Magnesium cations ether complexes

The styrylpyrilium salt derivatives (130) undergo (2 + 2)-cycloaddition to afford the corresponding dimers. The magnetic properties of the radical cations formed from these dimers were compared with those formed from (130). Styryl dyes of the type shown as (131) undergo E-Z isomerization on irradiation at 436 nm. The dyes align themselves in the pattern shown in (132, where the filled blob represents the crown ether complex). These undergo dimerization on irradiation to afford compounds (133), from which the magnesium ions can be removed. 

The halide radical anion (6) dissociates to give a carbon radical (R, where a radical is defined as a reactive intermediate with one electron in a p-orbital see Chapter 7, Section 7.4.3) and a halide anion, X. If X and 5 react with each other, a Mg-X bond is formed and the magnesium complex becomes a radical (6) rather than a radical cation. Note that the radical cation can accept electron density from the electron-rich X. If 6 subsequently reacts with the carbon radical (R ), Grignard reagent (7) is generated. This sequence is taken to be the mechanism of Grignard reagent formation from alkyl halides 1. The ether... 

FIA—CE has also been coupled with contactless conductivity detection (C4D) for online analysis of metal cations (ammonium, potassium, calcium, magnesium, and sodium as complexes in aqueous 18-crown-6-ether-acetace electrolyte solution) [86]. In this system the ends of the separation capillary and the electrodes were placed opposite to each other into tubings which acted as flow-through channels. 

---