Reactions of acetylenes with noble-metal halides. VI. The reactions of 2-butyne with chlorodicarbonylrhodium dimer

Abstract

Chlorodicarbonylrhodium dimer ([Rh(CO)2Cl]2) reacted with 2-butyne at 80° in benzene to give a mixture of compounds which contained hexamethylbenzene, duroquinone, chloro(π-duroquinone)-rhodium dimer, and chloro(π-tetramethylcyclopentadienone)rhodium. At 25° 2-butyne and [Rh(CO)2Cl]2 reacted to give a brown solid of variable composition (C), which could not be purified. Reaction of (C) with CO in methylene chloride gave a related solid (D) also of variable composition. Treatment of (C), or better (D), with an excess of triphenylphosphine gave chloro(dimethylmaleyl)bis(triphenylphosphine)-rhodium and (Ph3P)2RhCOCl. The former was identified by analysis, spectra, and its oxidation to dimethylmaleic anhydride. Reaction of (D) with p-toluidine gave chloro(dimethylmaleyl)carbonylbis(p-toluidine)rhodium, which on treatment with excess triphenylphosphine also gave chloro(dimethyl-maleyl)bis(triphenylphosphine)rhodium.