Mononuclear thiocyanate containing nickel(II) and binuclear azido bridged nickel(II) complexes of N4-coordinate pyrazole based ligand: Syntheses, structures and magnetic properties

• Synthesis of two mononuclear nickel(II) complexes of the type [NiL(NCS)2].
• Two new azido bridged dinickel(II) complexes of the type [Ni2(L′)2(N3)2(μ-N3)2].
• Ligands are tri and tetradentate nitrogen coordinating sites.
• Structure and magnetic properties of the complexes.
• Binuclear complexes show ferromagnetic interaction with J values from19 to 32 cm−1.

Two mononuclear nickel(II) complexes [NiL1(NCS)2] (1) and [NiL2(NCS)2] (2) and two azido bridged binuclear nickel(II) complexes [Ni2(L1′)2(N3)2(μ-N3)2] (3) and [Ni2(L2′)2(N3)2(μ-N3)2] (4), where L1, L2, L1′ and L2′ are N,N-diethyl-N′,N′-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine (L1), N,N-bis((1H-pyrazol-1-yl)methyl)-N′,N′-diethylethane-1,2-diamine (L2), N,N-diethyl-N′-((3,5-dimethyl-1H  -pyrazol-1-yl)methyl)ethane-1,2-diamine (L1′) and N-((1H-pyrazol-1-yl)methyl)-N′,N  ′-diethylethane-1,2-diamine (L2′) have been synthesized and characterized by microanalyses and physico-chemical methods. Single crystal X-ray diffraction analyses revealed that complexes 1 and 2 are mononuclear NCS− containing Ni(II) complex with octahedral geometry and complexes 3 and 4 are end-on (μ-1,1) azido bridged binuclear Ni(II) complexes with distorted octahedral geometry. Variable temperature magnetic studies of the complexes 3 and 4 display ferromagnetic interaction with J values 19 and 32 cm−1, respectively.