Anionic Chains of Parent Pnictogenylboranes

摘要

We report on the synthesis and structural characterization of unprecedented anionic parent compounds of mixed Group 13/15 elements. The reactions of the pnictogenylboranes H2E-BH2 center dot NMe3 (1a = P, 1b = As) with phosphorus and arsenic centered nucleophiles of the type [EH2](-) (E = P, As) lead to the formation of compounds of the type [H2E-BH2-E'H-2](-) (2: E = E' = P; 3: E = E' = As; 4: E = P, E' = As) containing anionic pnictogen-boron chain-like units. Furthermore, a longer 5-membered chain species [H2As-BH2-PH2-BH2-AsH2](-) (5) and a cyclic compound [NHCdipp-H2B-PH2-BH2-NHCdipp](+)[P5B5H19](-) (6) containing a n-butylcyclohexane-like anion were obtained. All the compounds have been characterized by X-ray structure analysis, multinuclear NMR spectroscopy, IR spectroscopy, and mass spectrometry. DFT calculations elucidate their high thermodynamic stability, the charge distribution, and give insight into the reaction pathway.