Crystal and molecular structures of 3,5-epidithio-2-nitroso-1,5-diphenylpenta-2,4-dien-1-one and 2,4-epidithio-1-nitro-1-nitroso-4-phenylbutadiene: heterocycles with a very short S ⋯ O intramolecular distance

Abstract

The crystal structures of 3,5-epidithio-2-nitroso-1,5-diphenylpenta-2,4-dien-1-one (II) and 2,4-epidithio-1-nitro-1-nitroso-4-phenylbutadiene (III) have been investigated by X-ray methods. The crystals of (II) are monoclinic, space group P2₁/c with Z= 4 in a unit cell of dimensions a= 15·545(7), b= 4·065(2), c= 24·297(10)Å, and β= 108° 13′(3′). The structure has been refined to R of 0·064 for 1778 non-zero reflections measured on an automatic diffractometer. The crystals of (III) are invariably twinned with (001) being the twinning plane, and are monoclinic, space group P2₁/c, with Z= 4 in a unit cell of dimensions a= 3·944(3), b= 16·420(7), c= 16·492(7)Å, and β= 96° 27′(4′). The structure has been refined in two-dimensions to R 0·11 for 274 0kl reflections. In (II), the nitroso-group rather than the carbonyl group is in close contact with S(3). The S(3)⋯ S(5) and S(3)⋯ O(2) distances are 2·178(2) and 2·034(5)Å, respectively. These values are compared with the lengths for the corresponding bonds in molecules where oxygen atoms of carbonyl groups and of nitro-groups are in contact with sulphur. The results of the rather limited analysis of (III) show that the nitroso-group rather than the nitro-group co-ordinates to S(2) and the derived bond lengths are consistent with these found in (II).