@article {771, title = {Predominantly sigma-bonded metal carbonyl cations (sigma-carbonyls): New synthetic, structural, and bonding concepts in metal carbonyl chemistry}, journal = {Chemistry-a European Journal}, volume = {9}, number = {8}, year = {2003}, note = {ISI Document Delivery No.: 669ZKTimes Cited: 7Cited Reference Count: 60}, month = {Apr}, pages = {1668-1676}, type = {Article}, abstract = {Predominantly sigma-bonded metal carbonyl cations (sigma-carbonyls) are conveniently generated in the Lewis superacid SbF5 or the conjugate Bronsted-Lewis superacid HF-SbF5, primarily by solvolytic or reductive carbonylations. Thermally stable salts are formed with the fluoroantimonate(v) ions [SbF6](-) and [Sb2F11](-). 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.}, keywords = {(2), carbonyl ligands, CATIONS, COMPLEXES, CRYSTAL, fluoro antimonates, FLUOROSULFATE, MOLECULAR-STRUCTURE, MONOXIDE, solid-state structures, superacidic systems, UNDECAFLUORODIANTIMONATE(V), VIBRATIONAL-SPECTRA, WEAKLY COORDINATING ANIONS, X-RAY-DIFFRACTION}, isbn = {0947-6539}, url = {://000182381600002}, author = {Willner, H. and Aubke, F.} }