Crystal structure and rotational barrier of octakis(bromomethyl)naphthalene

Samah Simaan; Vered Marks; Hugo E Gottlieb; Amnon Stanger; Silvio E Biali

doi:10.1021/jo026343s

Crystal structure and rotational barrier of octakis(bromomethyl)naphthalene

J Org Chem. 2003 Jan 24;68(2):637-40. doi: 10.1021/jo026343s.

Authors

Samah Simaan¹, Vered Marks, Hugo E Gottlieb, Amnon Stanger, Silvio E Biali

Affiliation

¹ Department of Organic Chemistry, The Hebrew University of Jerusalem, Israel.

PMID: 12530901
DOI: 10.1021/jo026343s

Abstract

Octakis(bromomethyl)naphthalene (4) adopts in the crystal a chiral conformation with a helical central naphthalene core and the bromomethyl groups disposed in an alternate up-down "in" arrangement. According to MM3 calculations, this conformation is less stable than the corresponding all alternated "out" form, while B3LYP/LANL2DZ calculations suggest the opposite stability order. The topomerization barrier (16.0 kcal mol(-1)) is ascribed to an enantiomerization process requiring 180 degrees rotation of all the bromomethyl groups and reversal of the helical sense of the naphthalene core.