Tricarbonylrhenium(I) halide complexes of chiral non-racemic 2-(dioxolanyl)-6-(dioxanyl)pyridine ligands: synthesis, NMR and DFT calculations

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Polyhedron-2003-22-3371 Download

Author(s): Peter J. Heard | Paul King | Phunrawie Sroisuwan | Nikolas Kaltsoyannis.

Type of publication: Journal paper

Abstract: The chiral non-racemic O/N/O donor ligands 2-[(4R,5R)-4,5-dimethyl-1,3-dioxolan-2-yl]-6-[(4R,6R)-4,6-dimethyl-1,3-dioxan-2-11yl]pyridine and 2-[(4R,5R)-4,5-dimethyl-1,3-dioxolan-2-deuteryl]-6-[(4R,6R)-4,6-dimethyl-1,3-dioxan-2-yl]pyridine were prepared in12a stepwise fashion form 2,6-dibromopyridine. Reaction with the pentacarbonylhalogenorhenium(I) compounds yields the complexes13[ReX(CO)3L], in which the ligands act in a N/O bidentate chelate fashion. There are eight possible diastereoisomers, three of which14are observable in solution. DFT calculations indicate that the relative stability of the diastereoisomers is SR5>RR5>15SS5RS5>RS6>SS6>RR6>SR6. Above ambient temperature, a dynamic process leads to the exchange of 2 of the 3 dia-16stereoisomers: the free energy of activation is ca. 79 kJ mol1. The results of the DFT calculations and the magnitude ofDGzsuggest17the dynamic process to be theflipof the co-ordinated acetal ring.

Published URL: https://core.ac.uk/reader/287588875

Date Published: January 1 2003

Publication title: Polyhedron

Publisher: Elsevier

Place of publication: London (United Kingdom)

Pages: 1-8

Subject(s): Chemistry

DOI: 10.1016/j.poly.2003.08.012POLY 4895DISK / 18/9/03No. of pages: 8DTD 4.3.1 / SPS-NARTICLE IN PRESS