Lanthanide (Ln) compounds have unique magnetic, optical and catalytic properties, which have been exploited in a wide range of technological applications. Ln bonding regimes are predominantly ionic and therefore lack directionality, but Ln coordination spheres can be controlled by using appropriate ligands and anaerobic environments. Design criteria for Ln complexes with ideal structural features for enhanced physiochemical properties have been developed. However, due to Ln ions being hard Lewis acids and their preferential binding to hard Lewis bases such as nitrogen, oxygen and halides, there is a paucity of Ln complexes containing softer p-block donor atom ligands. This is exemplified by the pnictogen series, where there are a large number of structurally authenticated examples of Ln amide complexes, but there are few heavy group 15 analogues in comparison. Over the past half a century, bis(trimethylsilyl)amide, {N(SiMe3)2} (Nʹʹ), has provided some of the most fascinating advances in Ln chemistry since the first reports of the landmark trigonal pyramidal Ln(III) complexes [Ln{N(SiMe3)2}3]. Seminal examples of Ln(II) Nʹʹ complexes include the first structurally characterized Eu(II) amide complexes [Eu{N(SiMe3)2}2(sol)2] (sol = DME or THF) and a rare Sc(II) complex [K(2.2.2cryptand)][Sc{N(SiMe3)2}3]. Although not as well-established, the larger bis(triisopropylsilyl)amide ligand, {N(Si i Pr3)2}, has also provided notable Ln(II) complexes, such as the near-linear examples [Ln{N(Si i Pr3)2}2] (Ln = Sm, Eu, Tm, Yb). In contrast, only a handful of f-element bis(trimethylsilyl)phosphide ({P(SiMe3)2}, Pʹʹ) complexes have been structurally authenticated to date, Conversely, to date there are no reported examples of f-element complexes containing bis(triisopropylsilyl)phosphide, {P(Si i Pr3)2}. Whilst H{N(Si i Pr3)2} and its alkali metal salts can be easily synthesized from commercially available reagents starting from NH3 or NaNH2, HP(Si i Pr3)2 was previously only isolated as a minor byproduct in 13% yield from the salt metathesis reaction of [Li(PH2)(DME)] with ClSi i Pr3; the THF-solvated lithium salt,