7-Isopropylidene-N 2,N 3,N 5,N 6-tetramethoxy-N 2,N 3,N 5,N 6-tetramethylbicyclo[2.2.1]hepta-2,5-diene-2,3,5,6-tetracarboxamide

Although the molecular structure of the title compound, C22H32N4O8, displays a twofold symmetry of the molecule including the methoxy and methyl substituents, no crystallographic twofold symmetry is observed in the X-ray structure analysis. The carbonyl O atoms alternately point to different sides of the plane defined by the carbonyl C atoms. Two methoxy groups are oriented inside the molecules cavity. The H atoms of two methyl groups are disordered over two orientations and were refined using a split model.

Although the molecular structure of the title compound, C 22 H 32 N 4 O 8 , displays a twofold symmetry of the molecule including the methoxy and methyl substituents, no crystallographic twofold symmetry is observed in the X-ray structure analysis. The carbonyl O atoms alternately point to different sides of the plane defined by the carbonyl C atoms. Two methoxy groups are oriented inside the molecules cavity. The H atoms of two methyl groups are disordered over two orientations and were refined using a split model.

Comment
The tertiary tetra amides of norbornadiene and quadricyclane are interesting compounds because of their ability to form stable complexes with alkali and alkaline earth metal cations. (Winkler et al., 2003a;Winkler et al., 2012) To enable further synthetic modifications, the tetrakis(N,O-dimethylhydroxyl amide) was synthesized. For the identification of this compound, a structure determination was performed.
In the structure of the title compound, the carbonyl atoms alternately point to different sides of the plane defined by the carbony C atoms. In contrast to the tetrakis(diethyl amide) (Winkler et al., 2003b), the methoxy substituents are small enough to point inside of the cavity of the molecule. although the molecule displays twofold symmetry no crystallographic twofold symmetry is oberved experimentally. In addition, no intramolecular hydrogen bonds are found.

Refinement
Hydrogen atoms were positioned with idealized geometry (methyl H atoms allowed to rotate but not to tip) and were refined isotropically with U iso (H) = 1.2 U eq (C)) (1.5 for methyl H atoms) using a riding model. The H atoms of two methyl groups are disordered and were refined using a split model with two orientations rotated by 60° and sof of 60:40.  Crystal structure of the title compound with labeling and displacement ellipsoids drawn at the 50% probability level.
Disordering is shown with full and open bonds. 7-Isopropylidene-N 2 ,N 3 ,N 5 ,N 6 -tetramethoxy-N 2 ,N 3 ,N 5 ,N 6 -tetramethylbicyclo[2.2.1]hepta-2,5-diene-2,3,5,6tetracarboxamide   Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.