Planar copper and nickel triangles with a guanidine-derived ligand

A novel guanidine-derived ligand with three tetradentate N 4 coordination sites and its trinuclear copper and nickel complexes, [Cu 3 ] and [Ni 3 ], were synthesized. X-ray structural analyses of [Cu 3 ] and [Ni 3 ] reveal the complexes to have planar triangular structures with pseudo C 3 symmetry. Magnetic measurements for [Cu 3 ] and [Ni 3 ] complexes indicate that antiferromagnetic interactions are operative in both complexes with intratriangle exchange coupling constants of g = 2.08(1), J = −130(1) cm −1 for [Cu 3 ], and g = 2.18(1), J = −14.9(1) cm −1 for [Ni 3 ]. [Cu 3 ] has a doublet spin ground state at low temperature, while the magnetic susceptibility data and magnetization curve suggest that the ground state of [Ni 3 ] is spin singlet.