Coordination versatility of 1,5-bis(salicylidene)carbohydrazide in Ni(II) complexes

• Ni(II) complexes of 1,5-bis(salicylidene)carbohydrazide (H3bsc) have been reported.
• Complex 1 is a bis chelate mononuclear complex of H3bsc in keto form.
• Unusual coordination behavior of H3bsc is observed in the tetranuclear complex 2.
• Complex 2 shows antiferromagnetic interaction between four Ni(II) centers.

Versatile coordination behavior of a polydentate Schiff base ligand 1,5-bis(salicylidene)carbohydrazide (H3bsc) has been explored in Ni(II) complexes. [Ni(H3bsc)2](ClO4)2 (1)·H2O·3CH3CN is a bis chelate mononuclear complex of H3bsc in keto form, and [Ni4(H0.5bsc)2(O2CCMe3)3(CH3OH)4](2)·2H2O·2CH3OH is a tetranuclear complex of H3bsc with an unusual coordination. In 2, one phenolate group of the ligand coordinates in a monodentate way and the other coordinates in a μ2-bridging mode to the Ni(II) center. This unusual coordination mode of the ligand stabilizes the Ni(II) complex in a tetranuclear form where the carbonyl oxygen of the ligand exists in between keto and enol form of bond order 1.5. Thus, complex 2, represents an unprecedented coordination behavior of the Schiff base ligand derived from carbohydrazides. Studies of magnetic properties of 2 are reported which reveal antiferromagnetic interaction between four Ni(II) centers.

Fascinating coordination behavior of a symmetrical polydentate Schiff base ligand 1,5-bis(salicylidene)-carbohydrazide (H3bsc) has been explored in Ni(II) complexes. 1 is a bis chelate mononuclear complex of H3bsc in keto form and 2 is a tetranuclear complex with a very unusual coordination mode which shows antiferromagnetic exchange interactions.Figure optionsDownload as PowerPoint slide