Elusive Trimethyllanthanum: Snapshots of Extensive Methyl Group Degradation in La-Al Heterobimetallic Complexes

作者：Gerber Laura C H; Le Roux Erwan; Tornroos Karl W; Anwander Reiner^*

来源：Chemistry - A European Journal, 2008, 14(31): 9555-9564.

DOI：10.1002/chem.200801174

• aluminum
• bond activation
• cluster compounds
• lanthanum
• methine
• methylene

Reactions of [La(AlMe4)(3)] and [Y(AlMe4)(3)] with PMe3 show that the phosphine can cleave Ln-CH3-Al linkages, separating Me3Al(PMe3). PMe3 (3 mol equiv) reacts with [Y(AlMe4)(3)] to give [(YMe3)(n)] contaminated with by-products containing phosphorus and aluminum. The La-based analog. [(LaMe3)(n)], is not formed selectively front the reaction of [La(AlMe4)(3)] with PMe3, or Et2O, which rather yields insoluble La/Al heterobimetallic products. Three multinuclear La-based clusters were obtained from a reaction of [La(AlMe4)(3)] with PMe3 (1 equiv) and identified by X-ray structure analyses. Each cluster exhibits extensive methyl group degradation and contains methylene, methine, or carbide moieties. [La4Al8(CH)(4)(CH2)(2)(CH3)(20)(PMe3)] has a {La-4(CH)(4)} cuboid core supported by AlMe3, Me2AlCH2AlMe2, and PMe3 ligands. [La4Al8(C)(CH)(2)(CH2)(2)(CH3)(22)-(toluene)] also contains a cuboid core, {La3Al(C)(CH)(2)(CH2)}, which includes one exo cubic lanthanum atom, and is supported by AlMe3, Me3AlCH2AlMe2, (AlMe4)(-), and toluene ligands. The lanthanum atoms in [La5Al9(CH)(6)(CH3)(30)] are arranged in a trigonal bipyramidal fashion with (CH) functionalities capping each face. The {La-5(CH)(6)}(3-) core is formally balanced by three AlMe2+ moieties and is additionally supported by six AlMe3 ligands. The unit cell contains two independent La-5 clusters, one with pseudo-C-3h and the other with pseudo-D-3 symmetry, as well as two molecules of the separation co-product Me3Al(PMe3).

• 出版日期2008