Tridentate phosphine ligands bearing aza-crown ether lariats

Abstract

Crown ethers are useful macrocycles that act as size-selective binding sites for alkali metals. These frameworks have been incorporated into a number of macromolecular assemblies that use simple cations as reporters and/or activity triggers. Incorporating crown ethers into secondary coordination sphere ligand frameworks for transition metal chemistry will lead to new potential methods for controlling bond formation steps, and routes that couple traditional ligand frameworks with these moieties are highly desirable. Herein we report the syntheses of a family of tridentate phosphine complexes bearing tethered aza-crown ethers (lariats) designed to modularize the variation of aza-crown size, lariat length, and distal phosphine substituents, followed by the synthesis and solid-state structures of Mo(III) complexes bearing cations in the pendent crown ethers.

Push–Pull Activation of N 2 : Coordination of Lewis Acids to Dinitrogen Complexes

“…In a 2019 study of the alkali series interactions with Molybdenum(0) dinitrogen complexes bearing a family of multidentate lariat ether phosphine ligands, Pap et al explored the potential of using tethered crown ethers for alkali cations solvation. 90 Reaction of the triphosphine ligands ({aza-n-crown}CH2CH2)P(CH2CH2PPh2)2 (n-crown-P3-Ph, n = 15, 18) with MoCl3(THF)3 followed by reduction with Na/Hg in presence of PMe3 afforded the N2 complexes 3 n . The related complex mer-(n-crown-P3i Pr)Mo(N2)2(PPh2Me) (4 n ) was isolated by ligand substitution between Mo(N2)2(PPh2Me)4 and (n-crown-P3-i Pr).…”