1,8 Interactions in Naphthalene Derivatives. An X-Ray Structure Determination and Nuclear Magnetic Resonance Studies of 1,8-Di( bromomethyl)naphthalene

Abstract

The conformation of 1,8-di(bromomethyl)naphthalene has been determined in the crystalline state and it has been found that the molecule has essentially twofold symmetry about the C-9-C-10 bond with the bromines located above and below the plane of the ring. The carbon-bromine bonds are inclined toward one another about 10º from planes perpendicular to the naphthalene ring which contain the C-14-11 and C-8-C12 bonds. This conformation has formally nonbonded H...Br distances of 2.85 A which are substantially less than the sum of the van der Waals radii and could well indicate some degree of electrostatic binding. The strain in the molecule is largely relieved both by in-plane and out-of-plane bending of the C-1-C-11 and the C-8-C-12 bonds as well as some skeletal distortion of the ring. Low-temperature proton nmr studies of 1,8-di(bromomethyl)naphthalene and some related compounds showed no evidence of barriers to rotation about the C-1-C-11 and C-8-C-12 bonds large enough to be detectable.