Tetranuclear complexes composed of dinickel(II) macrocyclic fragments bridged by 5,5′-(1,3-phenylene)bis-1H-tetrazolato and N,N-bis(tetrazol-5- ato)amine coligands: Synthesis, structures and magnetic properties

摘要

The dinuclear nickel(II) complex [Ni_2LCl]~+, where L~(2-) represents a 24-membered macrocyclic hexamine-dithiophenolate ligand, reacts with 5,5′-(1,3-phenylene)bis-1H-tetrazole and N,N-bis(tetrazol-5-yl)amine to give the tetranuclear complexes [(Ni _2L)_2(N_4C-X-CN_4)]~+, where X = 1,3-C_6H_4 (1) and NH (2). The new complexes were both isolated as perchlorate or tetraphenylborate salts and characterized by elemental analysis, UV/Vis, IR spectroscopy, and X-ray analysis. The crystal structures of the tetraphenylborate salts show bridging bistetrazolato moieties joining two dinuclear [Ni_2L]~(2+) fragments through their ring N2 and N3 atoms. Temperature-dependent magnetic susceptibility measurements reveal the presence of weak ferromagnetic exchange interactions between the Ni~(II) ions in the binuclear [Ni_2L]~(2+) subunits with magnetic exchange coupling constant values of J_1 = 16.6 cm ~(-1) for 1[BPh_4]_2, and J_1 = 16.8 cm~(-1) for 2[BPh_4]_2 (H = -2JS_1S _2). The exchange coupling constant J_2 across the bistetrazolato bridge in both compounds is less than 0.1 cm~(-1), which suggests that no significant interdimer coupling occurs across the linking tetrazolato moieties.