Scheme 12.

Synthesis of Pyrazole ligand N,N-bis(2(1′,5,5′-trimethyl-1H,1′H- [3,3′-bipyrazol]-1-yl)ethyl)propan-1-amine (L) (140) and bis-pyrazole coordination complexes (141–144). Reagents and conditions: (a) TsCl₂/CH₂Cl₂, 0 °C 5 h, 60%; (b) Propylamine/K₂CO₃/CH₃CN, reflux, 15 days, 30%; (c) CuCl₂.2H₂O, MeOH, diethyl ether, 25 °C, 6 days, 44%; (d) Ni(ClO₄)₂.6H₂O, MeOH, diethyl ether, 25 °C, 8 days, 29%; (e) No(ClO₄)₂.6H₂O, MeOH, diethyl ether, 25 °C, 9 days, 35%; and (f) FeCl₂ then KnCS, EtOH, 25 °C, 6 days, 37%.