SYNTHESIS AND CHARACTERIZATION OF ETHYLIDYNEARSINE

Ethynylarsine (2a) is synthesized by reaction of arsenic trichloride w ith ethynyltributylstannane followed by a chemoselective reduction of the formed ethynyldichloroarsine (1a). The base-induced rearrangement of compound 2a on a solid base in VGSR conditions leads to ethylidynea rsine (3a) characterized by H-1 and C-13 NMR and by microwave spectros copy. The rotational spectrum of 3a is recorded in the frequency range 90-470 GHz. Rotational and centrifugal distortion constants are deter mined and the quadrupole hyperfine structure is analyzed. The structur e of CH3C drop As has been estimated from the rotational constants of eight different isotopic species and from ah initio calculations. Comp ound 3a exhibits a low stability at 0 degrees C in deuteriochloroform (tau(1/2) Ca. 1 h) or in the gaseous phase at a pressure of 10 Pa (tau (1/2) Ca. 30 min).