Interconversible cis and trans rotational isomers of 1,8-di(1-naphthyl)naphthalene.

New stable cis and trans rotational isomers of 1, 8-di (1-naphthyl) naphthalene were prepared by the Kharash-type Grignard cross-coupling of 1-naphthylmagnesium iodide and 1, 8-diiodonaphthalene in the presence of N, N'-bis (1-methyl-3-oxobutylidene) ethylene-diaminatonickel (II). Thermoanalytical and proton magnetic resonance spectral studies indicated that both rotamers are stable in the solid state as well as in a solution, but are interconversible at temperatures above their melting points. A convenient method, obtaining pure trans rotamer from the equilibrium mixture of both rotamers, is also presented.