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Carbene-Pnictinidene Adducts.
Anthony J. Arduengo1, Joseph C. Calabrese, Alan H. Cowley
1DuPont 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.
Inorganic Chemistry
|May 7, 1997
Summary
Stable nucleophilic carbenes form adducts with pnictinidenes, creating polarized bonds. Structural and spectroscopic analyses reveal unique bonding characteristics in these novel carbene-pnictinidene compounds.
Area of Science:
- Organometallic Chemistry
- Main Group Chemistry
- Supramolecular Chemistry
Background:
- Stable nucleophilic carbenes (SNCs) are versatile ligands in organometallic chemistry.
- Pnictinidenes (Pn) are reactive species analogous to nitrenes and carbenes, featuring a pnictogen element (N, P, As, Sb, Bi).
- Adduct formation between SNCs and main group elements offers pathways to novel bonding motifs.
Purpose of the Study:
- To synthesize and characterize novel adducts of stable nucleophilic carbenes with pnictinidenes.
- To determine the X-ray crystallographic structures of these carbene-pnictinidene adducts.
- To investigate the electronic properties and bonding characteristics of the pnictinidene-carbene bond.
Main Methods:
- Direct reaction of 1,3-dimesitylimidazol-2-ylidene with pnictinidene cyclic oligomers.
- Synthesis of adducts using phenylphosphorus dichloride and 1,3-dimesitylimidazolin-2-ylidene.
- Characterization via X-ray crystallography and Nuclear Magnetic Resonance (NMR) spectroscopy, specifically 31P NMR.
Main Results:
- Formation of stable adducts between 1,3-dimesitylimidazol-2-ylidene and phenylphosphinidene, phenylarsinidene, (trifluoromethyl)phosphinidene, and (pentafluorophenyl)arsinidene.
- Structural data reveal small C-Pn-C angles (97-102°) and a minor shortening of the Pn=C double bond.
- 31P NMR shifts indicate highly shielded phosphorus centers in phosphorus adducts, consistent with polarized structures.
Conclusions:
- Carbene-pnictinidene adducts exhibit strongly polarized pnictinidene-carbene bonds.
- The structural and spectroscopic data support the formation of stable, unique bonding arrangements.
- These findings expand the scope of stable carbene chemistry and provide insights into main group element bonding.