Analysis of Boranes and Carboranes by Mass Spectrometry

Tuning a modular system – synthesis and characterisation of a boron-rich s-triazine-based carboxylic acid and amine bearing a galactopyranosyl moiety

“…For compound 15, the mass spectrum was very characteristic, because the isotopic pattern clearly showed the replacement of two chloro substituents by two carborane clusters. 42,43 In summary, the two target molecules 5 and 16 were obtained in good to excellent yield. Due to their different functional groups (R-COOH in 5 and R-NH 2 in 16), coupling with a large variety of different biomolecules as tumour-selective carriers can be envisaged for application in BNCT.…”

“…In the case of compound 12, mass spectrometry was a very informative characterisation method, as the characteristic isotopic pattern for molecules with 20 boron atoms was observed. 42,43 Single crystals of 12 could be obtained from n-hexane/ethyl acetate solution. The molecular structure is depicted in Fig.…”

Small Heteroborane Cluster Systems. 8. Preparation of Phosphaborane Clusters from the Reaction of Polyhedral Boranes with Low-Coordinate Phosphorus Compounds: Reaction Chemistry of Phosphaalkynes with Decaborane(14)1

“…The insertion of only the phosphorus atom and not the carbon atom of the phosphaalkyne unit into the cage framework was initially somewhat surprising. Phosphaalkynes have been found to react more similarly to alkynes than to nitriles in a variety of reactions. ,,,, The lower electronegativity of phosphorus most likely significantly contributes to this reactivity by inducing a reversal of the polarity in phosphaalkynes relative to nitriles. Thus, in phosphaalkynes, the phosphorus has a small partial positive charge, while in nitriles the nitrogen has a much larger and negative partial charge. , A directly analogous reaction for the phosphaalkynes to alkynes would have resulted in the insertion of both the phosphorus and the carbon into the cluster framework, forming a closo -cage system.…”

Reactive intermediates and molecular beam mass spectra of the boranes [1]

“…On the basis of their "stability," melting points, and chemical reactions, Alfred Stock classified [3] the boranes into two series, the "stable" B,H,+, (or B,H,(BH,),) [9], and the "unstable" BnHn+6 (or B,H,(BH,),). These molecules are listed, respectively, in columns 1 and 3 of table 2.…”

“…As the importance of this insidious steady state pyrolysis became evident, another goal of our:work became to determine more reliable fragmentation patterns. In this regard Stock [3] and subsequent workers [9] had classed the boranes into "stable" (BnHn+4) and "unstable" (B,H,+ 6 ) series, based on their physical and chemical properties. To some extent it seems that the mass spectrum is a useful means of classifying molecules into these series.…”