title: Complexation behavior of two-coordinated carbon compounds containing fluorenyl ligands.
abstract: DFT calculations using BP86 in conjunction with the SVP and TZVPP basis sets as well as ab initio calculations at SCS-MP2 have been carried out for six dicoordinated carbon molecules CLL' where L is a fluorenyl carbene while L' is a phosphine PH3 (1) or PPh3 (2) or a carbene, i.e. NHCMe (3), benzannulated NHCMe (4), cycloheptatrienylidene (5) and benzannulated cycloheptatrienylidene (6). The complexes of these compounds with one and two AuCl moieties were also calculated. The monoaurated adducts of 1-4 have the AuCl fragment η(1) coordinated to the central carbon atom. The complexes 5(AuCl) and 6(AuCl) have AuCl η(2) bonded across a C=C double bond. Three different bonding modes are found as energy minima for the diaurated species LL'C-(AuCl)2. The AuCl fragments are found to be either both coordinated η(1), both coordinated η(2) across double bonds, or a combination of the two. According to the electronic structure analysis of the free compounds, 1 and 2 might best be classified as carbenes, 3 and 4 as bent allenes while 5 and 6 are typical allenes. The complexation with AuCl reveals that 1-4 may exhibit chemical behaviour which is typical for carbones and thus, they may be termed "hidden carbones". The AuCl complexes show that compounds 5 and 6 are classical allenes.
authors.affiliation: Department of Chemistry, University of Stellenbosch, Private Bag X1, Matieland, Stellenbosch, South Africa. ce@sun.ac.za
authors.forename: Catharine
authors.initials: C
authors.lastname: Esterhuysen
authors.forename: Gernot
authors.initials: G
authors.lastname: Frenking
mesh_terms: D002244:Carbon / Q000737:chemistry*; D005449:Fluorenes / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D011789:Quantum Theory
chemical_list: D005449:Fluorenes; D008024:Ligands; D002244:Carbon