Molybdenum triazolylidene complexes for the N-alkylation of diamines with alcohols

Catalytic borrowing hydrogen reactions (BH) represent an interesting and powerful example of environmentally sustainable processes in synthetic chemistry, as they allow the preparation of high-value-added products. Nowadays, the use of earth-abundant metal-based homogeneous catalytic systems, such as molybdenum triazolylidene complexes, for BH reactions is particularly attractive due to the inexpensive and readily available nature of these complexes. Following the work reported by Royo’s group on the use of Mo triazolylidene complexes for the synthesis of quinolines via BH,2 this thesis explores another BH transformation, the N-alkylation of o-phenylenediamine with benzyl alcohol in the presence of t-BuOK. Accordingly, several Mo compounds containing donor ligands were synthesized, focusing particularly on Mo triazolylidene complexes of the general type [Mo(L1)(CO)4]. To obtain these compounds, bis-triazolylidene polydentate ligands were tried to synthesize, including two newly designed tetradentate ligands, L2 and L3. All successfully isolated Mo complexes were then evaluated in the selected BH reaction. Once [Mo(L1)(CO)4] was identified as the most active homogeneous pre-catalyst, the reaction conditions were optimized. In addition, detailed studies on the solvent effect in the N-alkylation and on the kinetic profile of the catalytic process were performed.