1600-5368 2-[ 4-( Dimethylamino ) phenyl ]-4 , 5-diphenyl-1 H-imidazole isopropanol solvate

# 2004 International Union of Crystallography Printed in Great Britain ± all rights reserved The title compound, C23H21N3 C3H8O, crystallizes with two independent molecules and two solvent molecules in the asymmetric unit. These are connected through hydrogen bonds between the NH group of the imidazole ring and the O atom of the isopropanol solvent molecule, as well as between the N atom of the imidazole ring and the OH group of the isopropanol solvent molecule.

The title compound, C 23 H 21 N 3 ÁC 3 H 8 O, crystallizes with two independent molecules and two solvent molecules in the asymmetric unit. These are connected through hydrogen bonds between the NH group of the imidazole ring and the O atom of the isopropanol solvent molecule, as well as between the N atom of the imidazole ring and the OH group of the isopropanol solvent molecule.

Comment
Microwave-assisted organic synthesis (MAOS) has been used extensively since the mid-1990s due to the availability of commercial microwave equipment and the continuing development of solvent-free reaction techniques. Different types of organic compounds have been synthesized using MAOS (Lidstro È m et al., 2001). Usyatinsky & Khmelnitsky (2000) have reported the use of this technique in the preparation of 2,4,5substituted imidazoles. Their synthetic procedure involved the condensation of 1,2-diaryethandienones with aldehydes and ammonium acetate as the source of ammonia with an acidic support (acidic silica) in a microwave oven. We attempted to synthesize 2-[4-(dimethylamino)phenyl]-4,5-diphenyl-1Himidazole using a similar technique in the absence of the acidic support media. Recrystallization of the reaction product from isopropanol afforded compound (I), as shown by single-crystal X-ray structure determination.
A comparison of the bond distances of the imidazole ring of (I) ( Table 1) and the mean values of the distances found in similar structures reported in the Cambridge Structural Database (Version 5.25 of October 2003;Allen, 2002) shows that the bond distance N1ÐC2 (N5ÐC25 for molecule B) is 0.010 A Ê smaller, the rest of the bond distances being practically the same.
In the crystal structure, the molecules are connected through hydrogen bonds (Table 2) between the NH group of the imidazole ring and the O atom of the isopropanol solvent molecule and between the N atom of the imidazole ring and the OH group of the isopropanol solvent molecule. There are short contacts between C9ÐH9 and O2 and between C28Ð H28 and O1(x À 1, y + 1, z).

Experimental
A mixture of 0.525 g (2.5 mmol) of benzil, 0.372 g (2.5 mmol) of dimethylaminobenzaldehyde and 7 g of ammonium acetate was irradiated with a microwave power of 262 W for 10 min. The reaction product was treated with 20 ml of diethyl ether and ®ltered. The solid residue was crystallized from isopropanol (m.p. 530±531 K).  All H atoms were placed in ideal positions and re®ned as riding [CÐH = 0.93 A Ê or 0.96 A Ê (methyl H atoms); U(H) = 1.2 or 1.5 (methyl H atoms) times U eq (parent atrom)], except for the H atoms linked to the N and O atoms, which were located in difference Fourier maps and re®ned freely.

Figure 1
The molecular structure of (I), showing the atom labelling and 50% probability ellipsoids. H atoms have been omitted for clarity, except for the H atom of the NH group and the solvent OH group. Molecule A is on the left and molecule B is on the right.