Polycyclic Peroxides and Planar Nitrogens
1,6-diaza-3,4,8,9,12,13-hexaoxabicyclo[4.4.4] tetradecane (hexamethylene triperoxide diamine or HMTD) was found, by a single crystal x-ray study, to have planar bridgehead nitrogen atoms. In order to study this planarity, a synthesis was developed for HMTD analogs. Crystals structures were obtained...
Summary: | 1,6-diaza-3,4,8,9,12,13-hexaoxabicyclo[4.4.4] tetradecane (hexamethylene triperoxide diamine or HMTD) was found, by a single crystal x-ray study, to have planar bridgehead nitrogen atoms. In order to study this planarity, a synthesis was developed for HMTD analogs. Crystals structures were obtained for three of these analogs, 1,6-diaza-3,4,8,9-tetraoxabenzotricyclo[4.4.2]dodec-11-ene (benzene tetramethylene diperoxide diamine or BTDD), 1,8-diaza-10,11,14,15- tetraoxatricyclo[6.4.4.0^(2,7)]hexadecane (cyclohexyl tetramethylene diperoxide diamine or CTDD), and 1,6-diaza3,4,8,9-hexaoxabicyclo[4.4.2]dodecane (hexamethylene diperoxide diamine or HMDD). These structures show that the planarity at the bridgehead nitrogen atoms of HMTD is no coincidence. MM2, a molecular mechanics program, was used to show that this planarity is not expected from simple force considerations. MNDO was used to model the molecule considering molecular orbitals. Finally, nuclear magnetic resonance techniques were used to obtain the energy of activation for inversion of HMTD and to determine the nuclear quadrupole coupling constants of the bridgehead nitrogen atoms at different temperatures, and thus their relative
planarity.
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