Polymetallic complexes linked to a single-frame ligand: cooperative effects in catalysis.

In an eco-friendly development, catalysis represents the key approach for converting raw materials into valuable products, particularly convenient for multi-step transformations. Mimicking Nature seems the smartest way to design poly-functional assemblies leading to the design of "synergic" catalysts. This perspective focuses on the advances in the conception of polymetallic catalysts bonded to a single ligand frame.

9,10-Dihydroanthracenyl structures: original ligands for the synthesis of polymetallic complexes through selective π-coordination.

N-Phenylsuccinimides and the corresponding pyrrolidines containing 9,10-dihydroanthracenyl skeletons were used for exploring their ability to coordinate RuCp(+) moieties through the aromatic rings. Electronic and steric tuning of ligands led to mono-, bi- and tri-metallic complexes. A full structural study was carried out in order to characterize the ruthenium organometallic compounds, proving the different coordination modes both in solution (NMR) and in solid state (X-ray diffraction). A modelling study (at DFT level) was completed with the aim to understand the selective π-coordination observed for mono- and bi-metallic complexes.

Tris(η(5)-cyclo-penta-dien-yl)-tris-[η(6)-[9,10-dihydro-anthracene-9,10-endo-3',4'-(N-benz-yl)pyrrolidine]]triruthenium(II) tris-(hexa-fluoro-phosphate) acetone disolvate.

In the title compound, [Ru(3)(C(25)H(23)N)(C(5)H(5))(3)]·3PF(6)·2C(3)H(6)O], the cation is a triruthenium complex of a 9,10-dihydro-anthracene derivative. Three RuCp(+) (Cp is cyclo-penta-dien-yl) groups are bonded to the three aromatic rings of the ligand. Surprisingly, the pyramidalized N atom of the heterocycle (Σ C-N-C = 329.0°) points towards the anthracenyl group, so losing its coordinative ability. There is an inter-molecular C-H⋯π inter-action involving an acetone mol-ecule and the adjacent benzyl ring of the ligand. In the crystal, mol-ecules are linked via a number of C-H⋯O and C-H⋯F inter-actions and a C-H⋯π inter-action, leading to the formation of a three-dimensional supra-molecular structure. One of the Cp groups is disordered over two positions, with refined occupancies of 0.695 (14):0.305 (14). Two of the three hexa-fluoro-phospate anions are disordered, with refined occupancies of 0.630 (6):0.370 (6) and 0.771 (8):0.229 (8). One of the two solvent acetone mol-ecules is also disordered, with refined occupancies of 0.82 (2):0.18 (2).

(1S,8R,15S,19R)-17-Benzyl-17-aza-penta-cyclo-[6.6.5.0(2,7).0(9,14).0(15,19)]nona-deca-2(7),3,5,9(14),10,12-hexa-ene chloro-form monosolvate.

In the title compound, C(25)H(23)N·CHCl(3), the dihydro-anthracene unit is bent with a dihedral angle between the benzene rings of 57.82 (8)°. The N atom of the pyrrolidine heterocycle, which has an envelope conformation with the N atom as the flap, exhibits a pronounced pyramidalization [Σ(C-N-C) = 328.07°], indicating an accentuated N-donor character. In the crystal, this behaviour is evident by the C-H⋯N hydrogen bond involving a solvent mol-ecule and the N atom. The absolute configuration at the C-atom fused positions of the pyrrolidine group were crystallographically confirmed to be S and R.