Study of Molecular Dynamics and the Solid State Phase Transition Mechanism for Unsymmetrical Thiopyrophosphate Using X-ray Diffraction, DFT Calculations and NMR Spectroscopy

Differential scanning calorimetry (DSC) and low-temperature X-ray diffraction studies showed that 2-thio-(5,5-dimethyl-1,3,2-dioxaphosphorinanyl)2‘-oxo-dineopentyl-thiophosphate (compound 1) undergoes reversible phase transition at 203 K related to the change of symmetry of the crystallographic unit...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2006-01, Vol.110 (2), p.761-771
Main Authors: Potrzebowski, Marek J, Bujacz, Grzegorz D, Bujacz, Anna, Olejniczak, Sebastian, Napora, Paweł, Heliński, Jan, Ciesielski, Włodzimierz, Gajda, Jarosław
Format: Article
Language:English
Subjects:
Diphosphates - chemistry
Magnetic Resonance Spectroscopy - methods
Models, Molecular
X-Ray Diffraction - methods
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Summary:Differential scanning calorimetry (DSC) and low-temperature X-ray diffraction studies showed that 2-thio-(5,5-dimethyl-1,3,2-dioxaphosphorinanyl)2‘-oxo-dineopentyl-thiophosphate (compound 1) undergoes reversible phase transition at 203 K related to the change of symmetry of the crystallographic unit. Solid state NMR spectroscopy was used to establish the dynamic processes of aliphatic groups and the phosphorus skeleton. 13C and 31P variable temperature NMR studies as well as T1 and T1 ρ measurements of relaxation times revealed the different mode of molecular motion for each neopentyl residue directly bonded to phosphorus. It is concluded that molecular dynamics of aliphatic groups causes different van der Waals interactions in the crystal lattice and is the driving force of phase transition for compound 1. Finally, we showed that very sharp phase transition temperature makes compound 1 an excellent candidate as a low-temperature NMR thermometer in the solid phase.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp0547459