Electrospray mass spectrometry of borane salts: The electrospray needle as an electrochemical cell.

Two borane salts ([(Me)4N][B3H8] and Cs[B3H8]) were examined by electrospray mass spectrometry in the positive ion mode. Acetonitrile solutions provided the most informative spectra; the salts exhibited a remarkable degree of clustering under electrospray conditions, and virtually all signals corresponded to cationic cluster ions of the general formula {[cation (m+)] x [anion (n-)] y }((mx - ny)+). In contrast, methanol solutions of these salts produced only B(OCH3) 4 (-) cluster ions under otherwise identical conditions. (11)B NMR analyses corroborate the identities of the methanol solution species that enter the electrospray source and the reaction product generated during the electrospray process.

Metastable and collision-induced fragmentation studies of all C4H 12Si (+) isomers; a systematic study of structure-reactivity relations.

Metastable ion (MI) and collision-induced dissociation (CID) mass spectra have been recorded and compared for all nine C4H12Si(+.) isomers. The (Me)4Si(+.), t-BuSiH 3 (+.) , s-BuSiH 3 (+) , and (Me)2EtSiH(+.) isomers have unique MI and CID mass spectra. The MI mass spectra, including the kinetic energy release values, of (Me)(i-Pr)SiH 2 (+.) and (Me)(n-Pr)SiH 2 (+.) are identical, which implies isomerization. MI data also suggest that a fraction of the n-BuSiH 3 (+.) ions rearrange into branched (Me)2EtSiH(+.) ions and a fraction of the n-BuSiH 3 (+.) ions rearrange into branched s-BuSiH 3 (+.) ions. A comparison with the isomeric C5H 12 (+.) pentanes reveals a crucial difference: H2 loss occurs for n-BuSiH 3 (+.) , i-BuSiH 3 (+.) , s-BuSiH 3 (+.) , (Me)(n-Pr)SiH 2 (+.) , (Me)(i-Pr)SiH 2 (+.) , and Et2SiH 2 (+.) , but not for any of the C5Hi 12 (+.) isomers. Generation of four- or five-membered silicon containing rings is suggested for H2 loss from the C4H12Si(+.) silanes.