title: Carbene-Pnictinidene Adducts.
abstract: The syntheses, characterizations, and X-ray crystallographic structure determinations are described for adducts of stable nucleophilic carbenes with pnictinidenes. The adducts between 1,3-dimesitylimidazol-2-ylidene and phenylphosphinidene, phenylarsinidene, (trifluoromethyl)phosphinidene, and (pentafluorophenyl)arsinidene are reported. These carbene-pnictinidene adducts are formed by the direct reaction of a stable nucleophilic carbene with the corresponding pnictinidene cyclic oligomers. The synthesis and structure of the adduct between 1,3-dimesitylimidazolin-2-ylidene and phenylphosphinidene from the reaction of 1,3-dimesitylimidazolin-2-ylidene with phenylphosphorus dichloride are also reported. These carbene-pnictinidene adducts possess strongly polarized pnictinidene-carbene bonds. The C-Pn-C angles are all typically small at 97-102 degrees, and there is only a 4% shortening of the nominal Pn=C double bond compared to the Pn-C single bond to the second substituent on the pnictogen. The (31)P NMR shifts of the phosphorus adducts suggest strongly shielded phosphorus centers in accord with the polarized structures.
authors.affiliation: DuPont Science and Engineering Laboratory,(5) Experimental Station, Wilmington, Delaware 19880-0328, and Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712-1167.
authors.forename: Anthony J.
authors.initials: AJ
authors.lastname: Arduengo
authors.forename: Joseph C.
authors.initials: JC
authors.lastname: Calabrese
authors.forename: Alan H.
authors.initials: AH
authors.lastname: Cowley
authors.forename: H. V. Rasika
authors.initials: HV
authors.lastname: Dias
authors.forename: Jens R.
authors.initials: JR
authors.lastname: Goerlich
authors.forename: William J.
authors.initials: WJ
authors.lastname: Marshall
authors.forename: Bernhard
authors.initials: B
authors.lastname: Riegel