Synthesis of the Bulky Phosphanide [P(Si ^<i>i</i> Pr ₃ ) ₂ ] ⁻ and Its Stabilization of Low-Coordinate Group 12 Complexes

Here, we report an improved synthesis of the bulky phosphanide anion [P(Si^<i>i</i>Pr₃)₂]^- in synthetically useful yields and its complexation to group 12 metals. The ligand is obtained as the sodium salt NaP(Si^<i>i</i>Pr₃)₂ <b>1</b> in a 42% isolated yield and a single step from red phosphorus and sodium. This is a significantly higher-yielding and safer preparation compared to the previously reported synthesis of this ligand, and we have thus applied <b>1</b> to the synthesis of the two-coordinate complexes M[P(Si^<i>i</i>Pr₃)₂]₂ (M = Zn, Cd, Hg). These group 12 complexes are all monomeric and with nonlinear P-M-P angles in the solid state, with DFT calculations suggesting that this bending is due to the steric demands of the ligand. Multinuclear NMR spectroscopy revealed complex second-order splitting patterns due to strong PP' coupling. This work demonstrates that the synthesis of <b>1</b> is viable and provides a springboard for the synthesis of low-coordinate complexes featuring this unusual bulky ligand.