Synthesis of a Ga-Stabilized As-Centered Radical and a Gallastibene by Tailoring Group 15 Element-Carbon Bond Strengths.

A convenient synthetic route to Ga-stabilized pnictogen-centered radicals and gallapnictenes by manipulation of pnictogen-carbon bond strengths is presented. Two equivalents of LGa (L = HC[C(Me)N(Dip)], Dip = 2,6--PrCH) react with CpAsCl (Cp = C(4--BuCH)) with formation of the arsenic-centered radical [L(Cl)Ga]As·. In contrast, the analogous reaction with TerSbCl (Ter = 2,6-MesCH; Mes = 2,4,6-MeCH) yields the gallastibene LGa═SbTer () containing a Ga-Sb double bond, whereas reactions of DipSbCl with one and two equivalents of LGa give the monoinsertion and bisinsertion products L(Cl)GaSb(ClDip) () and [L(Cl]Ga]SbDip (), respectively. - were structurally characterized by single crystal X-ray diffraction. The description of as an arsenic-centered radical is consistent with results of electron paramagnetic resonance and density functional theory (DFT) studies. The π-bonding in LGa═SbTer () is estimated to 10.68 kcal mol by variable-temperature (VT) NMR spectroscopy, and DFT studies reveal a significant π-bonding interaction between Sb and Ga.