Ferromagnetic Exchange Coupling in Ni(II) Complexes with a Coordinated Boron-Oxamido Radical: A Result of Spin State Transition

A Ni(II) coordination complex 1 with a novel boron-oxamido radical ligand was synthesized and isolated. Reactions of 1 with N,N-dimethyl-4-pyridinamine (DMAP) and 4,4'-bpy resulted in 2 and 3, respectively, accompanied by the spin state transition from S = 1/2 to S = 3/2. Both 2 and 3 were isolated as stable crystals and characterized to feature an S = 3/2 spin state, with the S = 1 Ni(II) atoms ferromagnetically coupled with the ligand-centred radicals, by SQUID measurement and EPR spectroscopy. Complex 3 represents the first example of one-dimensional magnetic chain constructed by S = 3/2 Ni(II)-radical units.

Automated summary

A Ni(II) coordination complex 1 with a novel boron-oxamido radical ligand was synthesized and isolated. Reactions of 1 with N,N-dimethyl-4-pyridinamine (DMAP) and 4,4'-bpy resulted in the formation of 2 and 3, respectively, and a spin state transition from S = 1/2 to S = 3/2. Both 2 and 3 were characterized to have an S = 3/2 spin state and ferromagnetic coupling between Ni(II) atoms and ligand-centered radicals through SQUID measurement and EPR spectroscopy. Complex 3 represents the first example of a one-dimensional magnetic chain constructed by S = 3/2 Ni(II)-radical units.