title: Aromaticity of tri- and tetranuclear metal-carbonyl clusters based on magnetic criteria.
abstract: Recently, the sigma-aromaticity model proposed for cyclopropane by Dewar was employed to account for the stability of Group 8 trinuclear metal-carbonyl compounds [M(3)(CO)(12)] (M=Fe, Ru, Os). This paper further examines this hypothesis and provides the first quantitative evidence for the sigma-aromatic/antiaromatic nature of the [M(3)(CO)(12)]/[M(4)(CO)(16)] species based on structural and nucleus-independent chemical-shift analysis. In addition, the extent of electron delocalization in tetrahedral [M(4)(CO)(14)] and butterfly [M(4)(CO)(15)] is analyzed and compared to prototype cycloalkanes. While remarkable analogies exist between metal-carbonyls and cycloalkanes, transition metals provide additional overlap possibilities that affect both the ring strain and the magnetic properties of metal-carbonyl rings and cages.
authors.affiliation: Department of Chemistry and Center for Computational Chemistry, University of Georgia, Georgia, Athens, Georgia 30602, USA. corminb6@ccqc.uga.edu
authors.forename: Clémence
authors.initials: C
authors.lastname: Corminboeuf
authors.forename: Paul von Ragué
authors.initials: Pv
authors.lastname: Schleyer
authors.forename: R Bruce
authors.initials: RB
authors.lastname: King
mesh_terms: D002248:Carbon Monoxide / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D008280:Magnetics; D019216:Metals, Heavy / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013237:Stereoisomerism
chemical_list: D019216:Metals, Heavy; D009942:Organometallic Compounds; D002248:Carbon Monoxide