title: Stereoselective recognition of vicinal diamines with a Zn(II) complex.
abstract: Zn(II) complex of L (N,N'-bis(2-pyridylmethyl)-N,N'-dimethyl-trans-1,2-diaminocyclohexane) binds chiral vicinal diamines (1,2-diphenylethylenediamine (dpen) and 1,2-diaminocyclohexane (dach)) stereoselectively. Crystallographic studies reveal that the ternary complex has the C2 symmetric cis-alpha topology. 1H NMR shows that the R,R form of the tetradentate zinc complex binds rapidly and reversibly to the R,R form of the diamine over the S,S form with a stereoselectivity of about 5:1. Although the diamine exchange rate is rapid it is slower than the NMR time scale, and distinct signals for the diastereomeric complexes are observed when racemic mixtures of the host and guest molecules are mixed. Origin of stereoselectivity is discussed in terms of steric effects.
authors.affiliation: School of Chemistry, Seoul National University, Seoul 151-747, Korea.
authors.forename: Woosung
authors.initials: W
authors.lastname: Kim
authors.forename: Soon Mog
authors.initials: SM
authors.lastname: So
authors.forename: Leonid
authors.initials: L
authors.lastname: Chagal
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Lough
authors.forename: B Moon
authors.initials: BM
authors.lastname: Kim
authors.forename: Jik
authors.initials: J
authors.lastname: Chin