Bachir Zouchoune

Structural and spin diversity of M(indenyl)2 transition-metal complexes: a DFT investigation

Full geometry optimization has been carried out for all the low-energy isomers of M(indenyl)2 (M = Sc–Ni, Y–Mo, Re, Ru–Pd). Depending on the electron-richness of the molecule, indenyl adopts various hapticities, some of them involving full or partial coordination of the C6 ring. Our results suggest that a judicious choice of substituents on the ligands should lead to the stabilization of η6-coordinated indenyl ligands. Indenyl is also shown to be quite flexible with respect to the spin ground state. Substituted iron and nickel bis-indenyl species should be characterizable in their triplet state. Thus, both from the point of view of coordination and the metal spin ground state, indenyl and cyclopentadienyl appear to behave quite differently.

Coordination chemistry of mixed M(benzene)(cyclopendadienyl) sandwich complexes: electronic properties and bonding analysis

DFT calculations using BP86 and B3LYP functionals have been carried out for all the low-energy structures of mixed [M(Bz)Cp]+1/0/−1 (M = Sc–Ni) sandwich complexes of benzene and cyclopentadienyl ligands. The electronic configuration of cationic, neutral and anionic metal–ligand complexes and their structures are discussed, wherein depending on the metal nature, the spin state and the metal valence electrons, a complete rationalization of the bonding has been provided for the [M(Bz)Cp]+1/0/−1 complexes. Benzene and cyclopentadienyl adopt unchanged η6 and η5 hapticities, respectively, for Sc, Ti, V, Cr and Mn complexes, but various coordination modes for Fe, Co and Ni were emphasized, according to the metal oxidation state and the complexs spin state, wherein some of them involve full or partial coordination of either benzene or cyclopentadienyl to satisfy the metals electron demand. The ionization energy and the electron affinity showed that the neutral 19-electron iron complex is the easiest oxidized and reduced species among all the complexes studied.

Electronic structure and structural diversity in indenyl in heterobinuclear transition-metal half-sandwich complexes

DFT calculations have been performed on a series of heterobimetallic compounds of the type [MCp][M′Cp](Ind), [M(CO)3][M′(CO)3](Ind) and [M(CO)2][M′(CO)3](Ind) (Ind = Indenyl). The flexibility of the indenyl ligand favors the possibility of the existence of several isomers. The structure and electronic structure of this large family of compounds were analyzed with respect to their total number of electrons (TNE) and the nature of the ancillary ligands. The structures with electron counts lower than 34-TNE adopt the syn configuration to compensate the electronic deficiency.