A new family of 1D, 2D and 3D frameworks aggregated from Ni5, Ni4 and Ni7 building units: synthesis, structure, and magnetism.

Three new Ni(ii)-clusters based on a Y-shaped ligand (biphenyl-3,4′,5-tricarboxylate, H3BPT), [Ni5(HBPT)4(OH)2(H2O)12]n (1), [Ni4(BPT)2(OH)2(H2O)6]n·4nH2O (2), and [Ni7(BPT)2(1,4-bib)2(OH)6(HCO2)2]n·3nH2O (3) (1,4-bib = 1,4-bi(1H-imidazol-1-yl)benzene), have been synthesized under solvothermal conditions. They were studied by infrared spectroscopy (IR), single crystal X-ray diffraction, thermogravimetric analysis (TGA), and magnetochemistry. The complexes contain low nuclear Ni-clusters as building units (BUs). Structurally, in 1, the cluster BUs of [Ni5(μ3-OH)2]8+ can be viewed as two reverse triangles sharing a common vertex, which are connected by the partially deprotonated μ2–η1:η1-HBPT2− forming 1D chains. The BUs of [Ni4(μ3-OH)2]6+ clusters in 2 can be considered as two reverse triangles sharing a common edge and extended by deprotonated μ6–η1:η1:η1:η1:η2-BPT3− constructing a 2D framework. The 3D framework of complex 3 consists of a [Ni7(μ3-OH)4(R-COO)7(HCO2)3] cluster BUs with fully deprotonated μ5–η1:η1:η1:η1:η1:η1-BPT3− and 1,4-bib ligands. In addition, TGA reveals that the complexes are stable in the range of 293–548 K. Magnetostructural analyses indicate ferromagnetic coupling of J1 = 1.85(3) and J2 = 2.25(4) cm−1 in 1 and J = 5.76(6) cm−1 in 2, whereas magnetic parameters J1 = −2.64(3), J2 = −23.22(19) and J3 = 12.02(5) cm−1 indicate an alternating magnetic chain (AF/F) in 3. [ABSTRACT FROM AUTHOR]