Self-assembly of Ni(II) metallacycles (a square and a triangle) supported by tetrazine radical bridges

Two Ni(II) molecular metallacycles of [Ni-4(bpz*tz(center dot-))(4)(N-3)(4)] (1) and [Ni-3(bpz(ph) tz(center dot-))(3)(pz(Ph)(Cl)tz(center dot-))(3)]center dot 1.3CH(3)OH center dot 9.3H(2)O (2) (bpz*tz = 3,6-bis(3,5-dimethyl-pyrazolyl)-1,2,4,5-tetrazine; bpz(Ph)tz = 3,6-bis (3-phenyl-pyrazolyl)-1,2,4,5-tetrazine; and pz(Ph)(Cl)tz = 3-bis(3-phenyl-pyrazolyl)-6-Cl-1,2,4,5-tetrazine) are reported. The single-crystal X-ray diffraction study reveals that 1 displays a square structure while 2 shows a triangle structure due to the steric effect, both bearing tetrazine radical bridges. Furthermore, magnetic studies reveal that the Ni-radical interaction in 1 is strongly ferromagnetic with a coupling constant (J) of 90.8 cm(-1) in the 2J formalist, while the overall antiferromagnetic behaviour of 2 is presumably due to the compete ferromagnetic (for the Ni-radical(bridging) interaction with J(1) = 95.4 cm(-1)) and anti-ferromagnetic (for the Ni-radical(terminal) interaction, J(2) = -57.5 cm(-1)) couplings.

Automated summary

Two Ni(II) molecular metallacycles with different structures and magnetic properties were reported in this study. The single-crystal X-ray diffraction revealed the square and triangle structures of these metallacycles, and the magnetic studies indicated differing magnetic behaviors due to the Ni-radical interactions.