Copper(II) tetrafluoroborate complexes with the N-3,N-4-bridging coordination of 1-(tert-butyl)-1H-tetrazole: synthesis, crystal structure and magnetic properties

摘要

1-(tert-Butyl)-1H-tetrazole (L) reacts with copper(II) tetrafluoroborate hexahydrate to give the complexes [Cu2L8(H2O)(2)](BF4)(4) (1) or [Cu3L6(H2O)(6)](BF4)(6) (2) depending on the reaction conditions. These complexes, as well as compound L, were characterized using single crystal X-ray analysis. Complex 1 was found to comprise a dinuclear complex cation [Cu2L8(H2O)(2)](4+) (the C-i symmetry point group), with six tetrazole ligands L showing monodentate N-4-coordination, and two ligands L providing two tetrazole ring N-3,N-4 bridges between the copper(II) cations; water molecules complete the distorted octahedral coordination of the metal ions. Complex 2 includes a linear trinuclear complex cation [Cu3L6(H2O)(6)](6+) (the S-6 symmetry point group), in which neighbouring copper(II) cations are linked by three ligands L via tetrazole ring N-3,N-4 bridges; central and terminal metal ions show octahedral CuN6 and CuN3O3 coordination cores, respectively. The temperature-dependent magnetic susceptibility measurements of complex 2 revealed that the copper(II) ions were weakly ferromagnetically coupled showing a coupling constant J of 2.2 cm(-1) {H = -2J(S1S2 + S2S3)}. The quantum-chemical investigation of the electronic structure and basicity of ligand L was carried out.