Document Type

Journal Article

Department/Unit

Department of Chemistry

Title

Stereoselective formation of helical binuclear metal complexes: synthesis, characterization, and crystal structures of chiral bis-rhenium(I) quaterpyridine complexes

Language

English

Abstract

A series of single-stranded helical Re(I) complexes, of formula [Re 2(L)Br2(CO)6], were prepared by reacting [Re(CO)5Br] with chiral quaterpyridines L1-4.By 1H and 13C NMR analysis, all the crude complexes consisted of a pair of stereoisomers. Sterically more demanding ligand L4 induced a higher ratio (80:20) than L1-3 (about 56:44). Stereochemically pure complexes could be obtained by recrystallization in CH2Cl2. X-ray crystallographic analysis of single crystals from purified complexes showed a single-stranded helical structure with a bridging ligand wrapped around two distorted octahedral rhenium metals, both of which possessed one bromide ligand and three carbonyl ligands in a fac coordination. The helical core is established by extensive noncovalent electrostatic interactions and chiral information is transmitted from the ligand to the helix through these interactions. Solution behavior was studied by CD spectroscopy, and the strong Cotton effect confirms the integrity of the helical structure in solution. The diastereoselectivity of helicates is proposed to be induced by steric interaction between the bromine atom and the substituent of the bridging ligand.© 2009 American Chemical Society.

Publication Date

2009

Source Publication Title

Inorganic Chemistry

Volume

48

Issue

9

Start Page

4108

End Page

4117

Publisher

American Chemical Society

DOI

10.1021/ic802249f

Link to Publisher's Edition

http://dx.doi.org/10.1021/ic802249f

ISSN (print)

00201669

ISSN (electronic)

1520510X

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