Synthesis and Kinetics of Sterically Altered Photochromic Dithizonatomercury Complexes

Following a previous study where 12 electronically altered dithizones were synthesized, here we report on attempts to synthesize 26 dithizones. The purpose was to explore the boundaries within which dithizones may be synthesized, explore spectral tuning possibilities, and investigate steric effects on the photochromic reaction of its mercury complexes. Contrary to expectation, large substituents like phenoxy groups increased the rate of the photochromic back-reaction. In the series H-, 2-CH₃-, 4-CH₃-, 3,4-(CH₃)₂-, 2-OC₆H₅-, and 4-OC₆H₅-di­thizon­ato­phenyl­mercury­(II), the lowest rate of 0.0004 s^–1 was measured for the 2-CH₃ complex, while the rate for the 2-OC₆H₅ derivative was 20 times higher. A solvent study revealed a direct relationship between dipole moment and the rate of the back-reaction, while the relationship between temperature and rate is exponential, with <i>t</i>_1/2 = 2 min 8 s for the 4-phenoxy complex. The crystal structures of two dithizone precursors, 2-phenoxy- and 4-phenoxy­nitro­formazan, are reported

A Protocol for the <i>exo</i>-Mono and <i>exo</i>,<i>exo</i>-Bis Functionalization of the Diazocine Ring of Tröger’s Base

An efficient protocol has been developed for the <i>exo-</i>mono and <i>exo</i>,<i>exo</i>-bis functionalization of Tröger’s base in the benzylic 6 and 12 positions of the diazocine ring. The lithiation of Tröger’s base using <i>s</i>-BuLi/TMEDA followed by electrophilic quench affords <i>exo</i>-mono- and <i>exo</i>,<i>exo</i>-bis-substituted derivatives of Tröger’s base in good to excellent yields. The variation of the number of equivalents of <i>s</i>-BuLi/TMEDA and the order of addition of the electrophile strongly govern the outcome of the reaction for each electrophile