Self-assembly of Ni(ii) metallacycles (a square and a triangle) supported by tetrazine radical bridges†
Abstract
Two Ni(II) molecular metallacycles of [Ni4(bpz*tz˙−)4(N3)4] (1) and [Ni3(bpzPhtz˙−)3(pzPh(Cl)tz˙−)3]·1.3CH3OH·9.3H2O (2) (bpz*tz = 3,6-bis(3,5-dimethyl-pyrazolyl)-1,2,4,5-tetrazine; bpzPhtz = 3,6-bis(3-phenyl-pyrazolyl)-1,2,4,5-tetrazine; and pzPh(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–radicalbridging interaction with J1 = 95.4 cm−1) and antiferromagnetic (for the Ni–radicalterminal interaction, J2 = −57.5 cm−1) couplings.