Isomerization pathway of a C-C sigma bond in a bis(octaazamacrocycle)dinickel(II) complex activated by deprotonation: a DFT study.

Unlabelled: The anti () to syn () isomerization pathway of the deprotonated form of the dimer with two nickel(II) 15-membered octaazamacrocyclic units connected via a carbon-carbon (C-C) σ bond was investigated. For the initial anti () structure, a deprotonation of one of the bridging ( hybridized) carbon atoms is suggested to allow for an to geometry twist. A 360° scan around the bridging C-C dihedral angle was performed first to find an intermediate geometry. Subsequently, the isomerization pathway was explored via individual steps using a series of mode redundant geometry optimizations (internal coordinates potential energy surface scans) and geometry relaxations leading to the structure. The prominent geometries (intermediates) of the isomerization pathway are chosen and compared to the and structures, and geometry relaxations of the protonated forms of selected intermediates are considered.

Supplementary Information: The online version contains supplementary material available at 10.1007/s00214-024-03100-5.