Ion Dynamics in Confined Spaces: Sodium Ion Mobility in Icosahedral Container Molecules

Abstract

Cation fluctuations within a molecular anionic ligand framework in crystals have rarely been observed. Veith et al. have studied local Li + ion fluctuations in crystalline lithium siloxyamides that contain either an anionic (N-Si-O-Si-N) 2À = (X 2À ) or (O-Si-N-Si-O) À = (Z À ) skeleton. [1] In the crystalline [Li 2 (Z) 2 ] and [Li 4 (X) 2 ] species, the metal movements proceed in a concerted fashion, that is, the cations jump simultaneously from filled to empty positions as electrostatically coupled (Li 2 ) 2+ and (Li 4 ) 4+ clusters, and the movements are linked to phase transitions, rotations, and oscillations of atoms and atom groups. A partial dynamic disorder of Li + ions has also been reported in the "onion"-type spherical cluster [Li 24 OI 2 (AsR) 10 ] (R = Me 2 (iPrMe 2 C)Si). [2] To date, ion fluctuations in crystallized "molecular boxes" have only been observed for Li + ions.We report herein on two compounds that are composed of a small central PH 2 À anion surrounded by a spherical outer shell consisting of twelve tert-butoxy anions. In this confined polyanionic space, that is, between the PH 2 À anion and the outer shell, 12 or 13 highly mobile sodium cations are embedded. One sodium ion can be reversibly added or removed to interconvert these aggregates.Brandsma et al. reported the synthesis of sodium dihydrogenphosphide, NaPH 2 , which uses the reduction of elemental phosphorus with sodium metal and subsequent addition of tert-butyl alcohol. This form of NaPH 2 is a versatile reagent for the preparation of organophosphorus compounds; [3] however, the nature of this "Brandsma reagent" was not known.We treated a solution of sodium in a 1:1 (by volume) mixture of ammonia and dimethoxyethane (dme) with red or white phosphorus. A yellow-brown suspension is obtained after approximately 1.5 h. After evaporation of the ammonia, the crude mixture, containing [NaPH 2 (solv) x ] and [NaNH 2 -(solv) x ] (solv = NH 3 or dme) suspended in dme, was treated with tert-butyl alcohol at À78 8C (Scheme 1 a). A clear solution is obtained at room temperature, which shows one triplet in the proton-coupled 31 P NMR spectrum at d = À307.7 ppm (J = 145.0 Hz) and a doublet at d = À2.24 ppm in the 1 H NMR spectrum (J = 145.0 Hz) for the PH 2 À ion. From this solution, colorless crystals of the composition Na 13 (dme) 3 (PH 2 )(OtBu) 12 (1) were obtained.When the crude NaPH 2 /NaNH 2 mixture is evaporated to dryness and toluene is used as solvent for the reaction with tBuOH, a new species 2 is detected by 31 P and 1 H NMR spectroscopy in the clear solution. The PH 2 À ion is identified through a triplet at d = À292.3 ppm (J = 142 Hz) in the proton-coupled 31 P NMR spectrum and a doublet at d = Scheme 1. Syntheses of 1 and 2.

A Sodium Sodate as Precursor for Lanthanide Bis(4-R-benzoxazol-2-yl)methanide Single-Molecule Magnets

“…In the sodium sodate 1 , one sodium ion is coordinated in a distorted tetrahedral fashion from two negatively charged ligands to give the anion, while the second metal cation is bound to six thf donor molecules in a distorted octahedral fashion, depicted in Figure . This structural motif is unique for all known alkali metal box derivatives and represents a rare example of sodium sodates. − The Na–N bond lengths range from 2.356(3) to 2.400(3) Å (ignoring disordered groups), which is comparable to other previously reported sodium derivatives . The N–Na–N bite angles range from 82.14(9)° to 83.10(9)° and are more acute than the ideal tetrahedral angle.…”

Phosphorous‐Functionalized Bis(acyl)phosphane Oxides for Surface Modification

“…NaPH 2 is easily obtained from elemental phosphorus, sodium, and tert ‐butanol in the form of a sodium tert ‐butylate aggregate, which is a versatile starting material for functional phosphorus compounds 20. Without prior isolation, the aggregate compound NaPH 2 (NaO t Bu) x 1 was reacted with mesitoyl chloride to give sodium bis(mesitoyl)phosphide 2 in >80 % yield as bright yellow crystals (Scheme ).…”

A Single Molecular Stoichiometric P‐Source for Phase‐Selective Synthesis of Crystalline and Amorphous Iron Phosphide Nanocatalysts

“…Only the structure of P 4 (CO t Bu) 4 , determined by X-ray diffraction methods, has been mentioned in a doctoral thesis without any further details. [57] In order to develop a rational synthesis, we prepared mesitoyl phosphane by reacting the double salt [NaPH 2 × Na(OtBu) x ] [58] with mesitoylmethylester ( Figure 1). H 2 P-COMes was obtained as a yellow oil in good yield and reacted without further purification with hexachloroethane and trimethylamine as HCl scavenger.…”