Yttrium Complexes with Group 13 Heterobenzene‐Type Ligands

The yttrium gallabenzene complex [(1‐Me‐3,5‐tBu2−C5H3Ga)(μ‐Me)Y(2,4‐dtbp)] is accessible from Y(GaMe4)3 and K(2,4‐dtbp) via a tandem salt metathesis/methane elimination (2,4‐dtbp=2,4‐di‐tert‐butyl‐pentadienyl). The pentadienyl ligand in [(1‐Me‐3,5‐tBu2−C5H3E)(μ‐Me)Y(2,4‐dtbp)] (E=Al, Ga) is easily displaced by salt metathesis with KC5Me5 and KTpMe,Me (TpMe,Me=tris(pyrazolyl‐Me2‐3,5)borato) affording [(1‐Me‐3,5‐tBu2−C5H3E)(μ‐Me)Y(TpMe,Me)] and [(1‐Me‐3,5‐tBu2−C5H3E)(μ‐Me)Y(C5Me5)]. The yttrium center in [(1‐Me‐3,5‐tBu2−C5H3E)(μ‐Me)Y(2,4‐dtbp)] readily forms adducts with neutral Lewis bases like 4‐DMAP (4‐dimethylaminopyridine), PMe3, DMPE (1,2‐bis(dimethylphosphino)ethane), and DME (1,2‐dimethoxyethane). In stark contrast, addition of TMEDA (N,N,N’,N’‐tetramethylethylenediamine) results in methyl/pentadienyl exchange between aluminum and yttrium resulting in [(1‐(2,4‐dtbp)‐1‐Me‐3,5‐tBu2−C5H3Al)Y(Me)(tmeda)]. The bonding features of the newly synthesized complexes are analyzed by single‐crystal X‐ray diffraction (SCXRD) and heteronuclear (89Y, 31P) NMR spectroscopy. The gallabenzene‐type yttrium complex [(1‐Me‐3,5‐tBu2−C5H3Ga)(μ‐Me)Y(2,4‐dtbp)] (A) is readily formed from one‐pot‐reactions using mixtures [YMe3]n/GaMe3/K(2,4‐dtbp) (2,4‐dtbp=2,4‐di‐tert‐butyl‐pentadienyl), while the remaining pentadienyl ligand gets easily displaced by pentamethylcyclopentadienyl affording B, showcasing the strong interaction of the heterobenzene ligand with the rare‐earth‐metal center. Distinct ligand bonding is revealed by 89Y NMR chemical shifts.