Hydrogen Bonded Framework Structures Constructed from 2-(Pyridyl N-oxide) Methylphosphonic Acid Ligands and Erbium(III)

Abstract

Syntheses for 2-(pyridyl N-oxide) methylphosphonic acid, 1-H, and 2-(pyridyl N-oxide) hydroxymethylphosphonic acid, 4-H, are described, and the crystal structures of both ligands are presented. Combination of these ligands with freshly prepared erbium hydroxide results in the formation of the isostructural complexes Er(L(-))(3)(LH).8H(2)O. The crystal structure determinations of the complexes show that extensive hydrogen bonding links the individual eight coordinate Er(L(-))(3)(LH) molecular units into a 3-D structure.

Structures and luminescent properties of lanthanide phosphonates

“…The amine and the hydroxyl groups of the ligand are not involved in metal coordination but participate in the interchain hydrogen bonding. Paine and coworkers synthesized two new phosphonic acids based on 2-pyridyl N-oxide, 2-(pyridyl Noxide) methylphosphonic acid (H 2 L 4 ) and 2-(pyridyl N-oxide) hydroxymethylphosphonic acid (H 2 L 5 ) [39]. Reaction of these ligands with freshly prepared erbium hydroxide resulted in two isostructural complexes, namely, Er(HL) 3 (H 2 L)·8H 2 O (L = L 4 or L 5 ).…”

Imidazole‐Bridged Tetrameric Group(IV) Heteroleptic Complexes from the Spontaneous Metal‐Ligand Assembly of a Potentially N4‐Tetradentate Ligand

“…The introduction of the pyridine pendant fragment was accomplished by deprotonation of the acidic methylene fragment of 3 followed by nucleophilic substitution on a freshly prepared 2‐picolyl chloride solution . The latter was released from the hydrochloride adduct upon salt washing with an aqueous NaHCO 3 solution (pH = 8) followed by extraction in organic solvents . The HCl‐free 2‐picolyl chloride was used immediately in the nucleophilic substitution with 3 – Na + without any further purification.…”

Coordination chemistry of phosphonic acids with special relevance to rare earths

“…In contrast, if a second coordinating group is correctly placed a layered compound does not form. For example, in 2-(pyridyl N-oxide) methylphosphonic acid (6) an eight-coordinate erbium compound of composition Er(HL − ) 3 (H 2 L)·8H 2 O was obtained [12]. Extensive hydrogen bonding links the individual molecular units into a 3-D structure.…”

“…Projection of the structure of Gd propylenediphosphonate down the caxis showing the pillared layered structure (a) and polyhedral version (b) (from Ref [12]. with permission).…”