Synthesis and Structural Characterization of 1,4-Diazadiene Imido Tungsten Complexes

The reaction of [W(NR)Cl4(L)] (R = Ph, Cy; L = thf) and Li2DAD (DAD = 1,4‐di‐tert‐butyl‐1,4‐diazabuta‐1,3‐diene) leads to the formation of [(DAD)W(NR)Cl2], R = Ph (1), R = Cy (2). Both complexes are examples of a growing class of complexes displaying an uncommon combination of two highly charged sterically demanding 6‐electron donors, NR2‐ and DAD2‐, at one coordination site. Surprisingly both complexes show weak Lewis acidity and don't react with σ‐donors such as PMe3 and THF. The crystal structure determination of 1 reveals a mononuclear molecular structure with folded DAD2‐ moiety. In accord with spectroscopic data and the W‐N, C‐N and C‐C bond lengths of the DAD ligand, the obtained compounds should be described as WVI imido ene‐diamido species.