Carbene-Pnictinidene Adducts.
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.
Arduengo
Anthony J.
AJ
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.
Calabrese
Joseph C.
JC
Cowley
Alan H.
AH
Dias
H. V. Rasika
HV
Goerlich
Jens R.
JR
Marshall
William J.
WJ
Riegel
Bernhard
B