Synthesis of the bulky phosphanide (iPr3Si)2P− and its stabilisation of low-coordinate group 12 complexes.

Here, we report the first practical synthesis of the bulky phosphanide anion [P(SiiPr3)2]− in synthetically useful yields, and its complexation to Group 12 metals. The ligand is obtained as the sodium salt (DME)NaP(SiiPr3)2 1 (DME = 1,2-dimethoxyethane) in 36% isolated yield and a single step from red phosphorus and sodium. This far exceeds previous yields for this ligand (ca. 9.8% overall yield over 3 steps), and we have thus applied 1 to the synthesis of the two coordinate complexes M[P(SiiPr3)2]2 (M = Zn, Cd, Hg). These Group 12 complexes are all monomeric and with non-linear P–M–P angles [163.593(18)° to 170.086(16)°] 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 2nd order splitting patterns due to strong PP’ coupling. This work demonstrates that the synthesis of 1 is viable and provides a springboard for the synthesis of low-coordinate d-block complexes featuring this unusual bulky ligand.