ABSTRACT Activation of white phosphorus (P 4) to smaller P n units by rare‐earth compounds remains a synthetic challenge. Here, we show that the rare‐earth dinitrogen complexes (Cp ttt) 2 M 2 (μ‐1, 2‐N 2) (M = Y, Gd; Cp ttt = 1, 2, 4‐tri (tert ‐butyl) cyclopentadienyl), reductively cleave P 4 to give a homologous series of phosphorus anions of decreasing nuclearity, that is, (Cp ttt) 2 M 2 (μ‐P 4) (1 M), (Cp ttt) 2 M 2 (μ‐η 2: η 2 ‐P 2) (2 M), and (Cp ttt) 2 M 2 (μ‐P) (3 M). Structural, spectroscopic, and computational studies show that 1 M contains a bicyclobutane‐like P 4 2– ligand, whereas 2 M features a side‐on coordinated P═P 2– ligand, and 3 M comprises a monatomic P 2– ligand formulated as a phosphorus‐centered radical with S = 1/2. The EPR spectrum of 3 Y confirms hyperfine coupling to 31 P and 89 Y, while magnetic measurements on 3 Gd reveal strong antiferromagnetic exchange between the Gd 3+ ions and the radical ligand. Density functional theory supports a three‐center π‐type M–P–M interaction in 3 M, with the unpaired spin localized primarily on phosphorus and only weak delocalization onto the metal centers. These findings represent progressive fragmentation of P 4 to diatomic and monatomic phosphorus anions by rare‐earth reagents, thereby extending the chemistry of multiply bonded phosphorus and persistent phosphorus radicals into the rare‐earth series.
Mondal et al. (Sun,) studied this question.