Reactivity of a Neutral Yttrium(III) Trimethyl Complex toward Brønsted and Lewis Acids

The present study corroborates that the neutral tridentate N-ligand 1,4,7-trimethyl-triazacyclononane (Me₃TACN) qualifies as a versatile platform to study selective ligand exchange with rare-earth-metal alkyl complexes, herein [(Me₃TACN)YMe₃]. Treatment with Brønsted-acidic bis(dimethylsilyl)amine, HN(SiHMe₂)₂, gave selectively the mono-exchanged heteroleptic complex [(Me₃TACN)YMe₂{N(SiHMe₂)₂}]. Depending on the molecular ratio employed, the reaction of [(Me₃TACN)YMe₃] with AlMe₃ resulted in the isolation/crystallization of [(Me₃TACN)YMe₂(AlMe₄)] [1 : 1] or ion-separated [(Me₃TACN)YMe(AlMe₄)][AlMe₄] [1 : 2] and [(Me₃TACN)YMe(AlMe₄)][Al₂Me₇] [1 : 3]. Analogous reactions with the heavier group 13 methyls GaMe₃ and InMe₃ generated mixed methyl/tetramethylgallato complex [(Me₃TACN)YMe₂(GaMe₄)] and ion-separated [{(Me₃TACN)YMe₂}₂{μ-Me}][InMe₄]. Finally, dimethylalane, HAlMe₂, converted [(Me₃TACN)YMe₃] into heteroaluminate [(Me₃TACN)Y(HAlMe₃)₃], representing an AlMe₃-supported, molecular yttrium trihydride complex. All compounds were investigated by single crystal X-ray diffraction (SC-XRD), homo- and heteronuclear (¹³C, ²⁷Al, ⁸⁹Y, ¹¹⁵In) NMR as well as IR spectroscopies and elemental analyses.