Negative ion mass spectra of nido carboranes

Pulsed positive negative ion chemical ionization mass spectrometry

“…Collisions between sample and a nitrogen metastable (N2*) also afford sample ions if the ionization potential of the organic is less than the energy content of the nitrogen metastable. Since the range of exothermicities associated with the above reaction pathways closely parallels the excess energy imparted to sample molecules during ionization by direct electron bombardment (1)(2)(3)(4)(5)(6)(7)(8) eV) (30), it is not surprising that nitrogen Cl and conventional El spectra are essentially identical. Similar results are obtained when argon rather than nitrogen is employed as the Cl reagent.…”

“…Despite the above difficulties, negative ion El mass spectrometry has found limited utility in the analysis of metalloorganic (1), organoboron (6), polynitro (1), polyfluoro (1), organosulfur (1), and organophosphorus (7) compounds. Spectra of these classes of com-pounds often exhibit both molecular anions and structurally significant fragment ions.…”

“…48, NO. 14,DECEMBER 1976 i v i d u a l n o t d i r e c t l y a s s o c i a t e AB -N2 + AB-+ +e AH ^-(0-3 eV)(6)…”

The aromatic diboracyclopropenyl (diboriranyl) anion; CB2H3 −: An ab initio study

“…The parent isoelectronic diboriranyl anion 5 has not been yet identified conclusively, although Onak et al [5] observed in the negative ion mass spectra of some nido carboranes a fragment, with m/z = 37, which corresponds to the possible monoisotopic compositions, C3H-, C2BH2, and CB:H3. The potassium salt of 6a, with bulky substituents, has been synthesized and characterized by NMR [6].…”

Chemical Ionization Mass Spectrometry of Nitroaromatic Vapors.

“…Production of negative and positive ions in a ratio of i:i~~ is not uncommon . Despite the above difficulties, nega tiv~ ion El mass ipectrometry has found limited utility in the analysis of rnetalloorganic ( 1), organoboron (6), polynitro (1), polyfluoro (1), organosul fur ( 1), and organophosphorus (7) compounds . Spectra of these classes of compounds often exhibit both molecular anions and structurally significant fragment ions.…”