Cationic Chains of Parent Arsanylboranes and Substituted Phosphanylboranes.

The substituted monomeric phosphanylboranes Ph P-BH ⋅NMe (1) and tBuHP-BH ⋅NMe (2) have been used for the synthesis of cationic chain compounds built up by R P-BH units. With a simple synthesis route, the highly stable cations [Me N⋅H B-PR R -BH ⋅NMe ] (1 a, 2 a) and [Me N⋅H B-PR R -BH -PR R -BH ⋅NMe ] (1 b, 2 b) (R =R =Ph; R =H, R =tBu) are obtained as iodide (I ) salts. The reaction of H As-BH ⋅NMe (3) with IBH ⋅SMe leads to [Me N⋅H B-AsH -BH -AsH -BH ⋅NMe ][I] (3 a), the longest so far known arsanylborane chain. Compound 3 a reacts with acetonitrile through a formal hydroarsination reaction to form [cyclo-{As(BH ⋅NMe )(CMe=NH) (BH )}][I] (4). The reported synthetic strategy has proved to be a powerful tool for the formation of small, cationic oligomeric units. All products were comprehensively characterized by X-ray structure analysis, NMR, IR spectroscopy, and mass spectrometry in cooperation with DFT calculations.