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

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Detail(s)

Original languageEnglish
Pages (from-to)4108-4117
Journal / PublicationInorganic Chemistry
Volume48
Issue number9
Online published7 Apr 2008
Publication statusPublished - 4 May 2009

Abstract

A series of single-stranded helical Re(I) complexes, of formula [Re2(L)Br2(CO)6], were prepared by reacting [Re(CO)5Br] with chiral quaterpyridines L14. 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 L13 (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.

Citation Format(s)

Stereoselective formation of helical binuclear metal complexes : Synthesis, characterization, and crystal structures of chiral bis-rhenium(I) quaterpyridine complexes. / Yeung, Ho-Lun; Wong, Wai-Yeung; Wong, Chun-Yuen; Kwong, Hoi-Lun.

In: Inorganic Chemistry, Vol. 48, No. 9, 04.05.2009, p. 4108-4117.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review