N,N′-Bis(1-acetylcyclohexyl)-1,8:4,5-naphthalenetetracarboximide

The title compound, C30H30N2O6, has crystallographic inversion symmetry with the nitrogen atom and the two oxygen atoms of the naphthalene diimide system deviating by −0.243 (2), 0.109 (3) and 0.247 (2) Å, respectively, from the plane defined by the carbon atoms.

The title compound, C 30 H 30 N 2 O 6 , has crystallographic inversion symmetry with the nitrogen atom and the two oxygen atoms of the naphthalene diimide system deviating by À0.243 (2), 0.109 (3) and 0.247 (2) Å , respectively, from the plane defined by the carbon atoms.

Related literature
For the structure of a related benzene diimide derivative with terminal acetylene groups, see: Gondo et al. (2009). For preparative procedures for compounds of this type and for the title compound, see Hamilton et al. (1998Hamilton et al. ( , 1999; Raehm et al. (2002); Ahn et al. (1997).

Comment
In a previous paper we presented the structure of a benzene diimide derivative having terminal acetylene groups and solubilizing cyclohexyl substituents (Gondo et al., 2009). This material was prepared for use in oxidative coupling reactions, thereby forming macrocycles as either isolated entities (Hamilton et al., 1999), or as components of molecularly interlocked systems (Hamilton et al., 1998;Raehm et al., 2002). As the corresponding naphthalene diimide analogues of benzene diimide derivatives are known to be generally more powerful electron acceptors, and have therefore been deployed in a variety of supramolecular and materials chemistry contexts, we attempted the preparation of the corresponding naphthalene diimide.
However, under all of the standard conditions generally employed in the synthesis of benzene and naphthalene diimides we failed to obtain the desired compound. Only under rather forcing conditions was evidence of ring closure to the imide obtained, but under these conditions adventitious water was also found to have added to the acetylene groups (Ahn et al., 1997). Thus, a low yield of the diketone was the only isolable material obtained from this process and the structure of this compound (I) is reported here.

Experimental
Under standard conditions for aromatic diimide formation (Hamilton et al., 1998;Hamilton et al., 1999) no evidence for the production of the desired acetylenic diimide could be found. Ring closure accompanied by unwanted addition of water across the acetylene bonds was observed using an alternative protocol (Ahn et al., 1997), giving a very low yield (<5%) of diketone (I) after chromatographic isolation. Single crystals of suitable quality for structure determination were grown by vapor diffusion of water into a DMF solution of the title compound.