Syntheses and crystal structures of 3-tert-butyl-4-cyano pyrazole and its complexes with cobalt(II), manganese(II), and copper(II)

A new pyrazole ligand, 3-tert-butyl-4-cyano pyrazole (Hpzt-Bu,4CN), has been synthesized. The crystal structure of this pyrazole, along with the syntheses and crystal structures of Co, Cu, and Mn complexes of this ligand, are reported. The uncoordinated pyrazole shows the formation of a cyclic hydrogen-bound dimer. The Co complex is octahedral, with four coordinated pyrazoles and two coordinated waters. The Mn complex is octahedral, with two coordinated pyrazoles, two coordinated triflates and two coordinated waters. A hydrogen bonding network involving the triflates and waters results in a linear double chain of Mn complexes. The Cu complex has two coordinated pyrazoles and two coordinated chlorides in a slightly distorted square-planar geometry, with a long bond to the cyano N atom of a neighboring Cu complex, forming a pseudodimer.

Graphical abstractThe syntheses and crystal structures of 3-tert-butyl-4-cyano pyrazole (Hpzt-Bu,4CN), Co(Hpzt-Bu,4CN)4(H2O)2, Mn(Hpzt-Bu,4CN)2(H2O)2(OTf)2, and Cu(Hpzt-Bu,4CN)2Cl2 are reported. Hpzt-Bu,4CN forms a cyclic hydrogen-bound dimer. Hydrogen bonding in the Mn complex results in a linear double chain. The Cu complex has a slightly distorted square-planar geometry, with a long bond to the cyano N atom of a neighboring Cu complex, forming a pseudodimer.Figure optionsDownload full-size imageDownload as PowerPoint slide