Metallboranate und Boranato-metallate. VI. Zur Reaction von Oniumboranaten mit Trimethylamin-Alan: Trimethylamin-boranato-alanat,BH4 · AlH3 · N(CH3) und Onium-alanate

Trimethylamine-alane adds to tetrabutylammonium tetrahydroborate in benzene to yield tetrabutylammonium trimethylamine-tetrahydroborato-trihydroaluminate. The BH₄ group of this novel complex hydrido-anion is bound via a single hydrogen bridge to the aluminium atom. Although there is ir-spectroscopic evidence for the formation of a similar tetraphenylphosphonium salt in the reaction of tetraphenylphosphonium tetra-hydroborate and trimethylamine-alane (employed in excess), the products are tetraphenylphosphonium tetrahydroaluminate and trimethylamine-tetrahydroborato-alane. However, tetraphenylarsonium tetrahydroborate yields triphenylarsine and (CH₃)₃N · AlH₂BH₄ under similar conditions. Tetrabutylammonium, tetraphenylphosphonium and tetraphenylarsonium tetrahydro-aluminates were prepared from the respective tetrahydroborate and LiAlH₄.