Al4(C5Me4H)4: Structure, reactivity and bonding

The synthesis of Al4R4 (R = C5(CH3)4H) (3) and the tetrahedral structure in the solid state are described. These results as well as the 27Al NMR spectra of 3 in solution are in line with the data obtained from DFT calculations. These calculations also support the failed observation of a monomeric AlR species in solution. Monomeric and tetrameric molecules of 3 are discussed with respect to those of (AlCp∗)4 (1) and (AlCp)4 (2). The increasing Al–Al bond strength from 1 to 3 and 2 from X-ray data is also supported by structural and energetic results from DFT calculations.