Theoretical study of the molecular structure and spectroscopic properties of 1,7;3,5-dimethylene-cis-1,3,5,7-tetraazadecalin

The equilibrium structure of 1,7;3,5-dimethylene-cis-1,3,5,7-tetraazadecali n was fully optimized at the MP2/6-3I+G(d) ab initio level of theory. The N MR C-13 and N-15 chemical shifts were analyzed by means of ab initio CSGT ( continuous set of gauge transformations) calculations performed with the HF -B3LYP/6-311 + G(2d,p) hybrid functional model. The He(I) photoelectron spe ctrum was measured and interpreted by means of ab initio OVGF (outer valenc e Green function) calculations, which give an overall consistent reproducti on of the energies and splittings of the uppermost bands. This heterocyclic molecule was found to be characterized by two moderately interacting group s of two nitrogen lone pairs each, outwardly directed in the small cage of C-2 symmetry. (C) 1999 Elsevier Science B.V. All nights reserved.