A Simple Coulombic Model for ³¹P NMR Spectra of Cluster-Encapsulated Phosphorus Atoms

Abstract

While sophisticated computational methods can predict 31P NMR spectra of phosphorus atoms encapsulated within Keggin-derived heteropoly tungstate and molybdate cluster anions, calculated and experimental chemical shift values typically deviate considerably from one another. Motivated by the observation that experimentally determined 31P chemical shift values within a series of water-soluble plenary and metal-cation substituted lacunary Keggin anions, [PM n W11O39](7–n)– (M n = Ag+, Zn2+, Nb5+, W6+) and [(PW11O39)2M n ](14–n)– (M n = Y3+, Zr4+), varied as a linear function of the oxidation states, n, of the complexed M n cations, a linear correlation was sought between observed chemical shift values and the net Coulombic forces experienced by the encapsulated phosphorus atoms. The Coulombic model based on Shannon radii, published electronegativity values, and bond angles from X-ray crystallographic data remarkably accounted for the relative 31P chemical shift values of phosphorus atoms in over 50 metal-oxide cluster anions, including large structures comprised of up to four Keggin-derived fragments with an overall R 2 value of 0.974. With the model being applied here to three cluster anions whose 31P chemical shift values are reported here for the first time, predicted and experimental values differed by only ±0.4 ppm.

Polyoxometalate-Complexed Indium Hydroxide: Atomically Homogeneous Impregnation via Countercation Exchange

“…The spectrum of a solid sample of 1 in KBr (black plot) is very similar to that of the WD complex, K 8 [α 2 -P 2 In III (OH)W 17 O 61 ] (green plot), which features "in-pocket" coordination of In III by the monovacant WD anion. 24,42 The single band at ca. 1090 cm −1 is assigned to vibrational modes of the two PO 4 moieties in [α 2 -P 2 In III (OH 2 )W 17 O 61 ] 7− .…”

“…We now report that In III -substituted monodefect WD cluster anions, [{α 2 -P 2 W 17 O 61 In III OH)] 8– , serve as ligands for stable, water-soluble complexes of predominantly cubic-phase (dzhalindite) In­(OH) 3 NCs ( 1 ). , The substituted In III ions are bound in a pentacoordinate “in-pocket” fashion within the defect site of the WD anions, and at neutral or slightly basic pH values, the OH – anions occupying their sixth coordination site are available to serve as donor ligands for In III atoms at the In­(OH) 3 NC surface.…”

Contrasting Trivalent Lanthanide and Actinide Complexation by Polyoxometalates via Solution-State NMR

“…Moreover, NMR spectroscopy appears ideally suited to study the POM− actinide complexes since many of the heteroatoms that can be inserted in POMs are NMR-active nuclei, including 31 P, 10/11 B, 75 As, 77 Se, and 29 Si. For instance, the tetrahedral PO 4 3− site embedded in phosphotungstate Keggin anions has been shown to give sharp signals in 31 P NMR spectra 46 and can be used to decipher their complexes' speciation in solution. In addition, variable-temperature NMR (VT-NMR) experiments can yield solution thermodynamics and kinetics information.…”

Effect of Mo/P Ratios on Dimensions: Syntheses, Structures, and Properties of Three New Molybdophosphates

“…Combining transition-metal (TM) cations and phosphates has been demonstrated to be a useful way to explore new functional materials. − During the past few decades, numbers of TM-containing phosphates have been successfully synthesized and widely used in different fields, such as catalyses, − magnetic functional materials, ion batteries, and nonlinear-optical (NLO) crystals . In these TM-containing phosphates, Mo-containing phosphates are of special importance for the following reasons.…”