3,3′-Bis(3-methoxybenzyl)-1,1′-ethylenediimidazolium dibromide

In the title compound, C24H28N4O2 2+·2Br−, the imidazolium cation is located on an inversion centre. The two imidazole rings are parallel to each other, whereas the imidazole and benzene rings make a dihedral angle of 77.25 (16)°. Nonclassical intermolecular C—H⋯Br hydrogen bonds link the imidazolium cations and the bromide anions into a three-dimensional network.

In the title compound, C 24 H 28 N 4 O 2 2+ Á2Br À , the imidazolium cation is located on an inversion centre. The two imidazole rings are parallel to each other, whereas the imidazole and benzene rings make a dihedral angle of 77.25 (16) . Nonclassical intermolecular C-HÁ Á ÁBr hydrogen bonds link the imidazolium cations and the bromide anions into a threedimensional network.
One of the common methods for the preparation of palladium NHC complexes is a one-pot reaction between an imidazolium salt and a palladium precursor in the presence of base . By this method, we prepared a palladium bis(NHC) complex from the title compound. Here, we report the crystal structure of the title compound.
The structure of the title compound is shown in Fig. 1. The bis(imidazolium) dication is located on an inversion center, with the two imidazole rings parallel to each other. The imidazole and benzene rings make a dihedral angle of 77.25 (16)°.
The bromide anions are involved in intermolecular hydrogen bonds of the type C-H···Br with the imidazolium cations, forming a three-dimensional hydrogen-bonded network ( Fig. 2 and Table 1).

Experimental
The compound was prepared according to the literature procedure . Suitable crystals were obtained by slow diffusion of diethyl ether into a DMF solution of the compound at room temperature. The average dimensions of the colorless, rod-like crystals are about 0.35 x 0.20 x 0.20 mm.

Refinement
All hydrogen atoms could have been located in the difference Fourier map; nevertheless, they were all positioned geometrically and refined as riding atoms, with C aryl -H = 0.93, C methyl -H = 0.96, C methylene -H = 0.97 Å; U iso (H) = 1.5U eq (C) for the methyl H atoms and U iso (H) = 1.2U eq (C) for all the other H atoms.