Tetraphenylpentalenide organolanthanide complexes

Abstract

The D_2h symmetrical 1,3,4,6-tetraphenylpentalenide is an excellent ligand for the stabilisation of strongly coloured bis(pentalenide) Ln^III sandwich complexes. These easily accessible compounds complement previously reported lanthanide organometallics and provide new opportunities to understand the roles of the f-orbitals in electronic structure and bonding.

Figure 1:

Dianionic 10π ligands for organometallic complexes (upper) and positional numbering and hapticity definition of pentalenides (lower).

Figure 2:

F-block bis(pentalenide) sandwich complexes (upper) and geometric definitions of relevant structural parameters (lower).

Figure 3:

Molecular structures of (left) the anion of 1-Ce(DME) and (right) the anionic MgY₂ pentalenide cluster of 3. Selected ellipsoids drawn at 50 % probability; H atoms, counter cations and lattice solvent omitted for clarity.

Figure 4:

UV-vis-NIR spectrum of 1-La in DME at room temperature (dark blue). TD-DFT calculated spectrum (red). Insets: representative NTOs (isosurfaces) for the most intense transitions.

Scheme 1:

Synthesis of [M(sol)_m][Ln^III(Ph₄Pn)₂]₂ (1-Ln) for Ln = Y, La, Ce, Tb, Yb from group 1 pentalenide salts (for Ln=Y, M=Li, n=4, X=Cl, sol=THF, M(sol)m = Li(DME)₃; for Ln=Ce, M=K, n=2, X=Br, sol=DME, M(sol)m = K(DME)₄; for Ln=Yb, M=Na, n=6, X=Cl, sol=THF, M(sol)m = Na(THF)₅), synthesis of the Mg analogue of 1-Y, [Mg(THF)₅][Y^III(Ph₄Pn)₂]₂ (2) from a magnesium pentalenide, and a half-sandwich cluster [MgCl(THF)₅][(Y^IIIPh₄Pn)₂(μ-Cl)₅Mg(THF)₄] (3).