Josh Abbenseth (@joshabbenseth.bsky.social)

Synthesis and Characterization of Monomeric, Dimeric, and Polymeric Rare-Earth Bis(trimethyl)silylphosphide Complexes Rare-earth (RE) bis(trimethylsilyl)amide ({N(SiMe3)2}−, N″) chemistry is well-developed, whereas RE bis(trimethylsilyl)phosphide {P(SiMe3)2}− (P″) chemistry is immature. Here, we report a convenient protonolysis route to dimeric RE P″ complexes [RE(P″)2(μ-P″)]2 (1-RE; RE = Y, Gd, Dy, Er) from parent [RE(CH2C6H4-o-NMe2)3] and excess HP″. The reactions of 1-RE with THF gave the monomeric RE P″ complexes [RE(P″)3(THF)2] (2-RE; RE = Y, Gd, Dy, Er), and treatment of 1-RE with 2 eq. of KP″ gave the RE “ate” coordination polymers [RE(P″)2(μ-P″)2K]∞ (3-RE; Y, Gd, Dy, Er). Complexes 1-RE, 2-RE, and 3-RE were characterized by single-crystal XRD, elemental analysis, and NMR, ATR-IR, and UV–vis–NIR spectroscopy. All paramagnetic 1-RE and 2-RE were also characterized by EPR spectroscopy and SQUID magnetometry, supported by ab initio calculations. We find that weak magnetic exchange interactions persist between RE centers in dimeric 1-RE and that their principal magnetic axes are oriented between the phosphide ligands as a consequence of the diffuse crystal field (CF) associated with the long RE–P bonds. For monomeric 2-RE, the principal magnetic axes are also oriented between ligands, reflecting competition between three long RE–P bonds and two short RE–O bonds that contribute approximately equally to the crystal field anisotropy. https://pubs.acs.org/doi/full/10.1021/acs.inorgchem.6c01375