Generation of Helical States – Breaking of Symmetries,Curie's Principle,and Excited States**

Herein, we deeply detail for the very first time mathematical concepts behind the generation of helical molecular orbitals (MOs) for linear chains of atoms. We first give a definition of helical MOs and we provide an index measuring how far a given helical states is from a perfect helical distribution. Structural properties of helical distribution for twisted -cumulene and cumulene version of Möbius systems are given. We then give some simple structural assumptions as well as symmetry requirements ensuring the existence of helical MOs. Considering molecules which do not admit helical MOs, we provide a first way to induce helical states by the breaking of symmetries. We also explore an alternative way using excited conformations of given molecules as well as different electronic multiplicities.     

Polymerization of norbornene with Co(II) complexes

The norbornene polymerization was studied in the presence of 6 pyridine bis(imine) cobalt(II) complexes activated with methylaluminoxane (MAO). Norbornene was also polymerized with CoCl₂ associated to MAO. All these catalytic systems generate an addition polymerization of norbornene, yielding fully saturated polymers. It was shown that the polymerization yield and the molar masses are highly dependant on several reaction parameters (monomer concentration, [Al]/[Co] ratio, polymerization temperature and time) and the frame of the ligand.