Diagonally Related s- and p-Block Metals Join Forces: Synthesis and Characterization of Complexes with Covalent Beryllium–Aluminum Bonds

Additions of beryllium–halide bonds in the simple beryllium dihalide adducts, [BeX₂(tmeda)] (X=Br or I, tmeda=N,N,N′,N′-tetramethylethylenediamine), across the metal center of a neutral aluminum(I) heterocycle, [:Al(^DipNacnac)] (^DipNacnac=[(DipNCMe)₂CH]⁻, Dip=2,6-diisopropylphenyl), have yielded the first examples of compounds with beryllium–aluminum bonds, [(^DipNacnac)(X)Al-Be(X)(tmeda)]. For sake of comparison, isostructural Mg–Al and Zn–Al analogues of these complexes, viz. [(^DipNacnac)(X)Al-M(X)(tmeda)] (M=Mg or Zn, X=I or Br) have been prepared and structurally characterized. DFT calculations reveal all compounds to have high s-character metal–metal bonds, the polarity of which is consistent with the electronegativities of the metals involved. Preliminary reactivity studies of [(^DipNacnac)(Br)Al-Be(Br)(tmeda)] are reported.