From Mononuclear Compounds to [2 × 2] Metallogrids: Ferromagnetically Coupled Systems Built by Nickel(II) and 3,6-Bis(2′-pyridyl)pyridazine (dppn)

Abstract

Mono-, di-, tri-, and tetranuclear compounds of nickel­(II) of formula [Ni­(dppn)3]­(NCS)2·0.5dppn (1), [{Ni­(dppn)­(NCS)}2(μ-dppn)­(μ-NCS)]­NCS (2), [Ni3(dppn)2(N3)2(μ-dppn)2(μ-N3)2]­(ClO4)2·CH3CH2OH·2H2O (3), and [Ni4(μ-dppn)4(μ-N3)4]­Cl4·5H2O (4) [dppn = 3,6-bis­(2′-pyridyl)­pyridazine] have been prepared and their structures determined by single crystal X-ray diffraction. Compound 1 is made up of mononuclear tris-chelated [Ni­(dppn)3]2+ units, thiocyanate counterions, and dppn molecules of crystallization. 2 contains cationic dinuclear units, the six coordination around each metal center being achieved with a pyridazine-dppn and one end-on thiocyanate nitrogen as bridges, a didentate dppn ligand and a terminally bound N-thiocyanate. The electroneutrality in 2 is reached by free thiocyanato anions. 3 contains bent trinuclear cationic units where all nickel­(II) ions exhibit a NiN6 chromophore with two bridging bis-didentate dppn and two end-on azide groups connecting the metal centers. Didentate dppn and monodentate azide ligands complete the six coordination at the peripheral nickel­(II) ions. The charge in 3 is counterbalanced by perchlorate anions and ethanol and water molecules of crystallization are also present. 4 exhibits a [2 × 2] grid-type of nickel­(II) ions where each pair of metal atoms are connected across a pyridazine-dppn fragment and one end-on azido group. Free chloride anions neutralize the positive charge of the grid and water molecules of crystallization are also present. Cryomagnetic susceptibility measurements on crushed crystals of 1–4, in the temperature range 1.9–300 K, reveal the occurrence of a Curie law for 1 and overall ferromagnetic behavior for 2–4 [J = +4.52(2) (2), +1.32(1) (3), and +10.50(2) and +9.10(2) cm–1 (4)]. The dominant ferromagnetic contribution across the single end-on thiocyanato (2) or azido bridges (3 and 4) versus the antiferromagnetic one through the pyridazine (2–4) is at the origin of this behavior. The values of the intramolecular ferromagnetic interactions in 3 and 4 were substantiated by DFT-type calculations. No ac signals were observed for 2–4 either in the lack of or under nonzero applied dc fields.

Recent developments in supramolecular complexes of azabenzenes containing one to four N atoms: synthetic strategies, structures, and magnetic properties

“…In 2020, based on 3,6-bis(2′-pyridyl) pyridazine ( L14 ) ligand four Ni II complexes (mono-, di-, tri-, and tetranuclear) are reported by Bruno et al 74 Among all four, tetranuclear Ni II complex [Ni 4 (μ- L14 ) 4 (μ-N 3 ) 4 ]Cl 4 ·5H 2 O ( NiL14 ) has formed [2 × 2] metallogrid complex and shown a distinct ferromagnetic interaction. L14 was synthesized by using a published procedure by Butte and Case in 1961.…”

Synthesis, Electrochemical and Antioxidant Properties of New Thiazolylazo‐based Mixed Ligand Metal Complexes

“…Therefore, it is important to investigate the relationship between ligands and the binding modes of the metals that form the complexes. [1] Mixed ligand complexes consisting of two or more different ligands have been widely explored because they can provide new materials with the useful magnetic exchange, [7][8][9][10] electrical conductivity, [11,12] photoluminescence, [13][14][15] nonlinear optical, [16,17] metallo-enzyme and antimicrobial activity properties. [18][19][20][21] Due to the presence of several heteroatoms acting as donor atoms, thiazolylazo dyes are an important class of organic complexing reagents.…”