Fourteen-electron species

Scheme 12 Fourteen-electron species as active catalysts [26a,b] (53 [27], 13 [12], 54 [28])...

Spectra from the chemiluminescent gas phase reactions at 0,5 torr, of ozone with ethylene, tetramethylethylene, trans-2-hutene, and methyl mercaptan at room temperature are presented, and a summary of the general features of the emissions obtained from reaction in the gas phase of ozone with fourteen different olefins is given. The emitting species in the ozone-olefin reactions have been tentatively identified as electronically excited aldehydes, ketones, and a-dicarbonyl compounds. The reaction of ozone with hydrogen sulfide, methyl mercaptan, and dimethylsulfide produces sulfur dioxide in its singlet excited state. 

Dis.solution of 1,4-dimethyl-, 1,3,5,7-tetramethyl, 1,3,5,7-tetra-phenyl- or S /m.-dibenzo-cyclooctatetraenes in a mixture of antimony pentafluoride and sulphonyl chloride fluoride at -78 results in the formation of species which, judged from their n.m.r. spectra, are planar dications with delocalised sets of six ir-electrons, giving rise to diamagnetic ring currents [59]. In the case of the dibenzo--derivative it appears that all fourteen ir-electrons are delocalised over the sixteen carbon atom periphery. 

Crystal structure analyses of fourteen aluminum(I) compounds have uncovered three structural motifs (1) four-membered AI4 rings for solvated aluminum(I) halides (AlX Do)4, (2) AI4 tetrahedra for aluminum(I) compounds with organic substituents (RA1)4, and (3) a monomer for the nacnac derivative. In addition, a tetramer-monomer equilibrium for (Cp Al)4 was established through VT NMR studies, and the gas-phase structure of Cp Al was determined by electron diffraction [20]. A dimeric structure similar to that of (Dipp Ga)2 [33, 34] was suggested for the transient Dipp Al species, a proposal based on the structure of the isolated cycloaddition product [27]. 

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