C- and N-Adducts of N-alkenyl substituted Arduengo carbene and N-alkyl substituted imidazole with PF: synthesis and structural investigation.

Thermolytic decomposition of 3,3'-(ethan-1,2-diyl)bis(1-methyl-1 H-imidazolium) bis-(hexafluorophosphate) ( 1) under reduced pressure results in a 1: 1 mixture of pentafluo-ro(1-ethenyl-3-methyl-2,3-dihydro-1 H-imidazole-2-ylidene-κ C)phosphorous ( 2) and penta- fluoro(3-methyl-1 H-imidazole-κ N)phosphorous ( 3) in an almost quantitate yield. Products 2 and 3 were isolated as individual compounds by fractional recrystallization from hot methanol. Direct observation of a 1: 1 co-crystallite of 2-pentafluorophosphanyl-1-ethenyl-3-methyl-1 H-imidazolium hexafluorophosphate and adduct 2 (compound 5) as a minor coproduct of this reaction reveals a complicated path of the thermolysis. Crystal and molecular structures of compounds 2, 3, and 5 were established by X-ray diffraction analysis. Compound 2 presents the first example of an N-alkenyl substituted Arduengo carbene adduct with a main Group element Lewis acid. Compound 3 presents the second known organic base N-adduct with PF. [ABSTRACT FROM AUTHOR]