The 1,3,5,7-tetraazadecalins: Structure, conformation, and stereoelectronics. Theory vs experiment

cis- and trans-1,3,5,7-tetraazadecalin (TAD) (2 and 4) and several N-Me (7- 9) and N-acyl (10-12) substituted derivatives in the cis and trans series w ere prepared and characterized. The X-ray structures of 4 and 12 were analy zed and the conformational equilibria of 2 and 11 were evaluated by VT-NMR. A QM (ab initio) and MM computational study was carried out, to provide re lative stabilities and geometrical parameters, which were compared with exp eriment. The MM2-AE (modified for the anomeric effect in N-C-N containing m olecules) and MM3 force fields are useful tools for these systems. The resu lts were interpreted in the light of stereoelectronic effects in such fused 1,3-diazane systems.