Toggle Main Menu Toggle Search

Open Access padlockePrints

The Newcastle University research output collection, currently available on ePrints, will shortly be moving to a new open repository platform, Figshare. To prepare for the data migration we have paused adding new content to ePrints, and will resume once the new repository is launched. During this time you will continue to have access to ePrints (but no new content will appear). We will share updates here when available.

Phosphorus NMR and ab initio modelling of P-N bond rotamers of a sterically crowded chiral β-P4S3 diamide

Lookup NU author(s): Dr Bruce Tattershall, Dr Julian Knight

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.

Abstract

Reaction of bicyclic β-P4S3I2 with enantiomerically pure (R)-Hpthiq (1-phenyl-1,2,3,4-tetrahydroisoquinoline) and Et3N gave a solution of a single diastereomer of the unusually stable diamide β-P4S3(pthiq)2, accounting for 83 % of the phosphorus content. Despite the steric bulk of the substituents, each amide group of this could adopt either of two rotameric positions about their P-N bonds, so that, at 183 K, 31P NMR multiplets for four rotamers could be observed and the spectra of three of them analysed fully. The large 2J(P-P-P) coupling became greater (253, 292, 304 Hz) with decreasing abundance of the individual rotamers. The rotamers were modelled at the ab initio RHF/3-21G* level, and relative NMR chemical shifts predicted by the GIAO method using a locally dense basis set, allowing the observed spectra to be assigned to structures. Calculations at the same level for the model compound α-P4S3(pthiq)Cl confirmed the assignments of low-temperature rotamers of α-P4S3(pthiq)I reported previously. Changes in observed P-P coupling constants and 31P chemical shifts, on rotating a pthiq substituent, could then be compared between β-P4S3(pthiq)2 and α-P 4S3(pthiq)I, confirming both sets of assignments. The most abundant rotamer of β-P4S3(pthiq)2 was not the one with the least sterically crowded sides of both pthiq substituents pointing towards the P4S3 cage, because of interaction between the two substituents. Only by using a DFT method could relative abundances of rotamers of β-P4S3(pthiq)2 be predicted to be in the observed order. Use of racemic Hpthiq gave also the two diastereomers of β-P4S3(pthiq)2 with Cs symmetry, for which the room temperature 31P{ 1H} NMR spectra were analysed fully. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.

Publication metadata

Author(s): Tattershall BW, Knight JG, Andrews MJ

Publication type: Article

Publication status: Published

Journal: Zeitschrift fur Anorganische und Allgemeine Chemie

Year: 2007

Volume: 633

Issue: 9

Pages: 1442-1450

ISSN (print): 0044-2313

ISSN (electronic): 1521-3749

Publisher: Wiley

URL: http://dx.doi.org/10.1002/zaac.200700161

DOI: 10.1002/zaac.200700161

Altmetrics

Altmetrics provided by Altmetric

Share