Yttrium Complexes with Group 13 Heterobenzene-Type Ligands

The yttrium gallabenzene complex [(1-Me-3,5-tBu₂ -C₅ H₃ Ga)(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 -C₅ H₃ E)(μ-Me)Y(2,4-dtbp)] (E=Al, Ga) is easily displaced by salt metathesis with KC₅ Me₅ and KTp^Me,Me (Tp^Me,Me =tris(pyrazolyl-Me₂ -3,5)borato) affording [(1-Me-3,5-tBu₂ -C₅ H₃ E)(μ-Me)Y(Tp^Me,Me )] and [(1-Me-3,5-tBu₂ -C₅ H₃ E)(μ-Me)Y(C₅ Me₅ )]. The yttrium center in [(1-Me-3,5-tBu₂ -C₅ H₃ E)(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 -C₅ H₃ Al)Y(Me)(tmeda)]. The bonding features of the newly synthesized complexes are analyzed by single-crystal X-ray diffraction (SCXRD) and heteronuclear (⁸⁹ Y, ³¹ P) NMR spectroscopy.