Covalent Hypercoordination: Can Carbon Bind Five Methyl Ligands?

• Published in: Angewandte Chemie International Edition Vol. 53; no. 30; pp. 7875 - 7878
• Main Authors: McKee, William C., Agarwal, Jay, Schaefer III, Henry F., Schleyer, Paul von R.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 21-07-2014; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: 3-center 2-electron bonds; Activation; Barriers; Bonding; Carbon; carbonium ions; Covalence; hypercoordinate carbons; hypercoordination; Ligands; σ-allyl bonding; hypercoordinate carbons; 3-center 2-electron bonds; carbonium ions; σ-allyl bonding; hypercoordination
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201403314

C(CH3)5+ is the first reported example of a five‐coordinate carbon atom bound only to separate (that is, monodentate) carbon ligands. This species illustrate the limits of carbon bonding, exhibiting Lewis‐violating “electron‐deficient bonds” between the hypercoordinate carbon and its methyl groups. Though not kinetically persistent under standard laboratory conditions, its dissociation activation barriers may permit C(CH3)5+ fleeting existence near 0 K.
C(CH3)5+ is the first example of a five‐coordinate carbon atom bound only to separate (monodentate) carbon ligands. This species illustrates the limits of carbon bonding, exhibiting Lewis‐violating “electron‐deficient bonds” between the hypercoordinate carbon and its methyl groups. Though not kinetically persistent under standard laboratory conditions, its dissociation activation barriers may permit C(CH3)5+ fleeting existence near 0 K.