Predominantly σ-Bonded Metal Carbonyl Cations (σ-Carbonyls): New Synthetic, Structural, and Bonding Concepts in Metal Carbonyl Chemistry

✍ Scribed by Helge Willner; Friedhelm Aubke

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 244 KB
• Volume: 9
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200390191

✦ Synopsis

Abstract

Predominantly σ‐bonded metal carbonyl cations (σ‐carbonyls) are conveniently generated in the Lewis superacid SbF~5~ or the conjugate Brønsted–Lewis superacid HFSbF~5~, primarily by solvolytic or reductive carbonylations. Thermally stable salts are formed with the fluoroantimonate(V) ions [SbF~6~]^−^ and [Sb~2~F~11~]^−^. The salts are characterised by analytical, structural, spectroscopic and computational methods. Most homoleptic carbonyl cations have very regular geometries, comensurate with their d‐electron configurations: linear (d^10^), square planar (d^8^) or octahedral(d^6^). The cations with metals in oxidation states of +2 or +3 are termed “superelectrophilic”. Extended molecular structures form by significant interionic CF contacts with electrophilic carbon as acceptor. To account for all experimental observations, a conceptually simple synergetic bonding model is proposed. An outlook at anticipated future developments based on very recent results is provided.