An Alumanylyttrium Complex with an Absorption due to a Transition from the Al-Y Bond to an Unoccupied d-Orbital.

The reaction between a dialkyl-substituted alumanyl anion and [Y(CH2 SiMe3 )2 (thf)3 ][BPh4 ] resulted in the formation of (dialkylalumanyl)yttrium complex 2, which exhibits the first 2-center-2-electron (2 c-2 e) Al-Y bond. The 1 H and 13 C NMR spectra of 2 together with an X-ray crystallographic analysis indicated a C2v symmetrical structure. DFT calculations on 2 revealed that its LUMO consists of overlapping 3 p- and 4 d-orbitals of the Al and Y atoms, respectively, and that the HOMO-LUMO gap is narrow. The UV/Vis spectrum of 2 exhibited a visible absorption at 432 nm, which suggests that the strong σ-donating and π-accepting character of the three-coordinate dialkylalumanyl ligand generates a colored d0 -complex that does not contain any π-electrons.