Sulfur-containing conjugated systems

Sulfur-Containing Conjugated n-Systems Annelated with Bicyclo[2.2.2]octene Frameworks... 

The synthesis by Mueller-Westerhoff and Alscher150 of the Ni, Pd and Pt dithiomalonaldehyde ( ptt ) complexes allowed the comparison of NMR chemical shift data between the parent even and odd systems with sulfur-containing conjugated ligands. The results are given in Table 2. 

An enormous amount of work has been done in this wide field and a number of excellent reviews on different aspects of sulfur electrochemistry has been published [1-7], so here we confine our attention to some principal reactions and interesting apphcations of both anodic and cathodic activation of sulfur-containing molecules. Compared to other chalco-genides, sulfur has frontier orbitals that have volume, symmetry, and energy more suitable for efficient interaction with adjacent carbon atoms. The ionization of molecular sulfur requires about 10 eV. Conjugation of the pz orbitals of sulfur with a 7T-system lowers the ionization potential by ca. 2 eV. For this reason, compounds of divalent sulfur undergo oxidation rather easily often giving rise to cation radicals or dications. The stability of this species is in line with the... 

After a plate has been exposed to the mobile-phase solvent for the required time, the compounds present can be viewed by several methods. Polynuclear aromatic hydrocarbons, other compounds with conjugated systems, and compounds containing heteroatoms (nitrogen, oxygen, or sulfur) can be viewed with long-and short-wave ultraviolet light. The unaided eye can see other material, or the plates can be developed in iodine. Iodine has an affinity for most petroleum compounds, including the saturated hydrocarbons, and stains the compounds a reddish-brown color. 

The heterocyclic thiazolium ring contains six n electrons. Each carbon contributes one electron, nitrogen contributes one electron, and sulfur contributes two electrons to the ring n system. The thiazolium ion is aromatic because it has 6 n electrons in a cyclic, conjugated system. 

The cation stacks containing essentially a conjugated system in which there is a species (usually sulfur or selenium) which has two valence states separated by small energies in the solid. 

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