Benzyl dihydrazone versus thiosemicarbazone Schiff bases: supramolecular arrangements of cobalt thiocyanate complexes and the generation of CoN6 and CoN4S2 coordination spheres

3 years ago

Benzyl dihydrazone versus thiosemicarbazone Schiff bases: supramolecular arrangements of cobalt thiocyanate complexes and the generation of CoN6 and CoN4S2 coordination spheres

Ghodrat Mahmoudi, Jan K Zareba, Fedor I Zubkov, Antonio Bauza, Maciej Kubicki, Atash V Gurbanov, Antonio Frontera

This study tackles the coordination chemistry of benzyl dihydrazone and thiosemicarbazone Schiff bases, featuring different chelation modes, steric bulk and reactivity towards cobalt(II) thiocyanate. The tetradentate benzyl dihydrazone ligands coordinate the Co(SCN)2 fragment leading to the CoN6 coordination spheres (1 - 3) while thiosemicarbazone ligands provide Co(III) complexes featuring CoN4S2 coordination spheres (4 and 5); in those complexes charge-balancing anions (SCN- and [Co(SCN)4]2- for 4 and 5, respectively) are formed. Hirshfeld Surface (HS) analysis revealed, amongst others, a substituent effect, reflected in the increasing share of H···H contacts in the row: -H < -CH3 < -Ph (for complexes 1, 2, 3, respectively). The H-bonding in compounds 4 and 5, and associated energies have been computed using DFT approach and appear to be crucial for the formation of those supramolecular systems. DFT study also suggested that H-bonded dimers in 5 are examples of the recently described "anti-electrostatic" H-bonds.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/ejic.201700955