We found that a slight excess of metal dibenzyl precursors was required in the preparation of 1-M to ensure no contamination of the product with proligand. This was likely due to the incomplete formation of the metal dibenzyl reagents generated in situ. We also found that it was not possible to purify the product if it was contaminated with proligand through recrystallization or via washings with hydrocarbons, particularly since the heavier 1-M have appreciable solubility even in apolar solvent media. Despite these issues, the yields of 1-M were consistently high (70-90%). We also investigated salt metathesis as an alternative methodology for the synthesis of 1-M, employing the ligand transfer reagent [{K(NPC-H)}2] and MI2(THF)x (M = Mg-Ba, x = 0; M = Eu, Yb, x = 2). This was successful in all trialled cases, with yields comparable to the protonolysis route, thus avoiding synthetic issues associated with the use of metal dibenzyl precursors (Scheme 1). Additionally, following the serendipitous synthesis of )the larger splitting was assigned to Si(a) and the smaller to Si(b) (Figure ). This was on that basis that in the solid state structures the N=P double bond was shorter than the C-P single bond (vide infra, Structural Characterisation), thereby increasing the coupling strength to phosphorus as the greater spatial overlap between the respective s-orbitals would lead to better communication of nuclear spin between nuclei.