The metastable ion supported fragmentations and fluorine transfer rearrangements of a series of fluoroaromatic heterocyclic derivatives of silicon, germanium and tin are reported. Of particular interest is the unique loss of neutral SiF, from the parent ion of (C,,F,),Si yielding the [C,,F,,]+. ion. These and similar rearrangements are discussed and structures are proposed for some of the ions observed. The general case of cyclic rearrangement intermediates prior to the loss of neutral metal fluorides from perfluoroaromatic derivatives is discussed. Losses of neutral metal fluorides from the parent ions appear to involve a species with increased co-ordination number about the central atom as an intermediate. In addition to (CI2F8),M, the following compound types were
The electron impact fragmentation of the trimethylamine adducts of BX, (X = H, F, CI, Br, and I) and BF, Br, (n + m = 3) have been examined at 70 eV. Trends in ion abundances are evident as the atomic weight of the substituent halide increases. The results are discussed in terms of boron-nitrogen and boron-halogen bond strengths, with reference to the effects of boron-halogen v-bonding. WHILE many physical methods have been applied to the study of amine adducts of the boron trihalides, no systematic mass spectral measurement is reported. We now report such a study. Further, in view of recent n.m.r. studies of the trimethylamine, diethyl ether, and 4-picoline adducts of mixed trihalides of boron1-3 and the isolation and characterization of F,BrB,NMe, and FBr,B,NMe,,4 we have included the latter two compounds.The results of these mass spectral measurements can be interpreted in terms of the relative acceptor strength of the boron trihalides and borane towards trimethylamine. They are consistent with other studies which indicate that borane and boron trifluoride are considerably weaker Lewis acids than boron trichloride,
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