Synthesis of cis-p-dioxano-12-crown-4 and X-ray crystallography of the (1:1) complex with lithium thiocyanate

Abstract

The synthesis of a novel 12-crown-4 analogue (cis-p-dioxano-12-crown-4 or cis-3,6,9,13,15pentaoxabicyclo[9.3.1]pentadecane) is described. The (1:1) LiNCS complex crystallizes in the monoclinic Cc space group; a = 8.4973(2) D, b = 18.0659(4) D, c = 8.9168(1) D, and β = 90.713(1)°with Z = 4. The crown adopts C 1 symmetry to which the Li + is coordinated in a rectangular pyramid with an apical -NCS.Résumé : On décrit la synthèse d'un nouvel analogue d'une 12-couronne-4 (cis-p-dioxano-12-couronne-4 ou cis-3, 6,9,13,15-pentaoxabicyclo[9.3.1]pentadécane). Le complexe (1:1) avec le LiNCS cristallise dans le groupe d'espace monoclinique Cc, avec a = 8,4973(2) D, b = 18,0659(4) D et c = 8,9168(1) D, β = 90,713(1)°et Z = 4. La couronne adopte une symétrie C 1 dans laquelle la coordination du Li + est s'effectue dans une pyramide rectangulaire avec un -NCS apical.

Solid state stereochemistry of crown ethers: X-ray crystal structure and 13C NMR studies of the LiNCS complex of 1,4,7,11-tetraoxacyclotetradecane

“…The O-C-C-O torsion angles in the complex are both within 4°of being perfectly gauche, in accordance with normal preferred complexation geometries for these units in related molecules (10)(11)(12). With respect to the overall conformation, it is of interest to compare the structure of the present complex with those found for other 14-crown-4 isomers.…”