Group 13 Heavier Carbene Analogues Stabilized by the Bulky Bis(4-benzhydryl-benzoxazol-2-yl)methanide Ligand.

On the basis of the bulky bis(4-benzhydryl-benzoxazyl-2-yl)methane ligand (BoxCH), neutral monovalent group 13 complexes [M(BoxCH)] [M = Tl (), In (), or Ga ()] have been synthesized by salt metathesis reaction of the corresponding potassium or sodium precursor and TlOTf, InOTf, or "GaI". The diiodido gallium species [GaI(BoxCH)] () was realized as a byproduct once the synthesis of was carried out at higher temperatures. The synthesis of [AlI(BoxCH)] () as a potential precursor for an aluminum(I) congener was accomplished by two alternative synthetic routes. During one of those procedures, [AlMe(BoxCH)] () was synthesized in good yields by deprotonation with an AlMe solution (method A). Subsequently, was converted to the monoiodinated species [AlMeI(BoxCH)] () using 1 equiv of I or to by iodination with 2 equiv of I at 70 °C for 4 days. As an alternative, complex could be prepared by iodination of 1 equiv of I and [AlH(BoxCH)] (), which was previously obtained by facile reaction of BoxCH and AlHNMeEt. All main products were completely characterized by nuclear magnetic resonance spectroscopy, mass spectrometry, elemental analysis, and single-crystal X-ray structure determination. Alane was additionally analyzed by solid-state fluorescence spectroscopy. Density functional theory calculations on [M(BoxCH)] [M = Tl (), In (), Ga (), or Al] revealed that the complexes consist of monovalent group 13 cations coordinated by an anionic (BoxCH) ligand similar to metallacycles incorporating a NacNac ligand.