N-(4-Chlorophenyl)maleimide

In the title compound, C10H6ClNO2, the dihedral angle between the benzene and maleimide rings is 47.54 (9)°. Molecules form centrosymmetric dimers through C—H⋯O hydrogen bonds, resulting in rings of graph-set motif R 2 2(8) and chains in the [100] direction. Molecules are also linked by C—H⋯Cl hydrogen bonds along [001]. In this same direction, molecules are connected to other neighbouring molecules by C—H⋯O hydrogen bonds, forming edge-fused R 4 4(24) rings.

In the title compound, C 10 H 6 ClNO 2 , the dihedral angle between the benzene and maleimide rings is 47.54 (9) . Molecules form centrosymmetric dimers through C-HÁ Á ÁO hydrogen bonds, resulting in rings of graph-set motif R 2 2 (8) and chains in the [100] direction. Molecules are also linked by C-HÁ Á ÁCl hydrogen bonds along [001]. In this same direction, molecules are connected to other neighbouring molecules by C-HÁ Á ÁO hydrogen bonds, forming edge-fused R 4 4 (24) rings.
RMF dedicates this work to the memory of Professor J. Valderrama. RMF is grateful to the Instituto de Química Física Rocasolano, CSIC, Spain, for the use of the license of Cambridge Structural Database System (Allen, 2002). This work was partially supported by the Universidad del Valle, Colombia.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2150).

Comment
It is known that cyclic unsaturated dicarbonyl compounds such as N-substituted maleimides can be used in free-radical-initiated polymerization processes upon exposure to light (Howell & Zhang, 2006). In order to study the possible application of N-(p-chlorophenylmaleimide) (I) in polymerization processes, and to explain its hydrogen bonding patterns, the synthesis and the study of the crystal structure are reported in this work. N-(p-nitrophenylmaleimide) (4NPMI) (Moreno-Fuquen et al., 2003), N-(o-chlorophenylmaleimide) (2ClPMI) systems (Miller et al., 2001) show a close analogy to the title compounds and are thus employed as a basic reference for comparison. Perspective view of (I), showing the atomic numbering scheme, can be seen in Fig.1. In the arylmaleimide systems the value of the dihedral angle between the benzene and imidic rings influences on the polimerization process, and the presence of different substituents in the benzene ring change the value of this angle (Miller et al., 2000). The photochemical properties of arylmaleimide systems depend on the value of this angle.
The dihedral angle between benzene and maleimide planes is 42.98 (5)° for 4NPMI, 66.10 (4) ° for 2ClPMI and 47.54 (9)°f or (I). The chlorine atoms, which are pending on the aromatic nucleus, tend to steer the crystal structure to a state characterized by a short axis (Sarma & Desiraju, 1986). For (I), the b axis has a small value [3.8589 (2) Å] and a Cl···Cl nonbonded contact is observed at the same distance. The crystal structure of (I) is stabilized by weak intermolecular C-H···O and C-H···Cl hydrogen-bonds (Nardelli, 1995) (Table 1). The molecules of (I) are linked into a three-dimensional framework by a combination of C-H···O and C-H···Cl hydrogen bonds. The formation of the framework can be explained in terms of three-one substructures. In the first substructure, atom C8 in the molecule at (x,y,z) acts as a hydrogen-bond donor to maleimidic atom O1 in the molecule at (-x,1 -y,1 -z) and atom C9 in the molecule at (x,y,z) acts as a hydrogen-bond donor to maleimidic atom O2 in the molecule at (1 -x,1 -y,1 -z). Both interactions generate dimers containing centrosymmetric rings with graph motif R 2 2 (8) (Etter, 1990) (Fig. 2, supp. material). These dimers are linked by C(5) chains which are running parallel to [100] direction. In the second substructure, atom C9 in the molecule at (x,1/2 -y,-1/2 + z) acts as a hydrogen-bond donor to atom Cl1 in the molecule at (x,y,z), similarly, atom C5 in the molecule at (x,y,z) acts as a hydrogen-bond donor to maleimidic atom O2 in the molecule at (x,1 + y,z) so generating a chain of edge-fused R 4 4 (24) rings along [001] (Fig.   3, supp. material). The third one-dimensional substructure is built by C-H···O hydrogen bonds. Atom C2 in the molecule at (x,y,z) acts as hydrogen bond donor to maleimidic O1 in the molecule at (-x,-1/2 + y,1/2 -z) so generating a C(7) chains in the [010] direction (Fig.4, supp. material). The low value of the dihedral angle between benzene and maleimide planes, allows to conclude that (I) is not a good candidate to use in a photopolymerization process.

Experimental
All reagents (purchased from Aldrich) and solvents were used as received. Column chromatography was performed using silica gel H60 to purify the intermediates and final products. Thin layer chromatography (TLC) was used to confirm the structure of the individual compounds.