Structures and Magnetic Properties of Carbonato-Bridged Hexanuclear Ni^II₄Ln^III₂ (Ln = Gd, Tb, Dy) Complexes Formed by Atmospheric Carbon Dioxide Fixation in the Absence of an External Base

Abstract

The reaction of the mononuclear Ni­(II) building block [NiL] of an asymmetrically dicondensed N2O3 donor Schiff base ligand, N-salicylidene-N′-3-methoxysalicylidene-1,3-propanediamine (H2L), with LnCl3·6H2O (Ln = Gd, Tb, Dy) in a 2:1 molar ratio leads to the formation of three hexanuclear carbonato-bridged Ni4Ln2 complexes formulated as [Ni4Ln2(CO3)2Cl2(L)2(L′)2(CH3CN)2]·4CH3CN·2H2O (Ln = Tb (2), Dy (3)), where H2L′ = N,N′-bis­(salicylidene)-1,3-propanediamine. In complex 1, the unsymmetrical nature of the Schiff base remains intact; however, in 2 and 3, between the two metalloligands coordinated to each Ln, one is the precursor [NiL] of the unsymmetrical ligand whereas the other [NiL′] of the symmetrical ligand, formed by an in situ aldehyde-exchange reaction during complex formation with Ln salts. The Ln­(III) centers are octacoordinated with a biaugmented-trigonal-prismatic geometry in all three complexes. In complex 1, half of the Ni­(II) centers possess a distorted octahedral geometry while the other half has a square-pyramidal geometry; all of the Ni­(II) centers in complexes 2 and 3 have a distorted-octahedral geometry. A magnetic study clarifies that the Ni–Ln magnetic exchange couplings are ferromagnetic. Though the complexes consist of a hexanuclear [Ln2Ni4] system, the magnetic properties have been analyzed on a trinuclear Ni–Ln–Ni basis. The exchange parameter 2J Gd–Ni/k B in 1 was estimated to be +0.61 to +0.84 K across the double-oxide bridges. Complexes 2 and 3 exhibited an indication of single-molecule magnets in an ac susceptibility study.

Assembly Studies of Two Planar Dy4 Single-Molecule Magnets

“…Further cooling to 2 K results in more and more fast reduction of the χ M T value to 23.29 cm 3 K mol –1 . The phenomena revealed in the χ M T versus T plots is possible owing to thermally depopulated excited-state Dy­(III) stark sublevels. ,− …”

Synthesis and crystal structures of two tri- and tetra-heterometallic Ni(ii)–Mn(ii)/Ni(ii)–Co(iii) complexes from two different Ni(ii)-containing metalloligands: effective catalytic oxidase activity and Schottky device approach

“…The interfacial series resistance of D1 was found to be significantly low, which indicates better charge kinetics than D2. The ideality factors for D1 and D2 were calculated as 0.92 and 1.22, respectively, using eqn (5). Given that D1 has a superior Schottky contact to D2, the ideality factor of D1 is almost equal to one.…”

“…In terms of catalytic, magnetic, biomedical, gas storage, and sensing activities, the metal complexes with N, O donor tetradentate ligands have multiple applications that are significant for the study of chemical science. [1][2][3][4][5][6] In the past, numerous heterometallic complexes have been created by directly mixing a metal centre with an N 2 O 2 donor Schiff base ligand. [7][8][9] These Schiff bases are widely used in coordination chemistry research due to their simple synthesis procedures, one-pot condensation of a diamine with substituted salicylaldehyde derivatives, and their exceptional complexing power.…”

Synthesis, crystal structure, and luminescence properties of a three-dimensional coordination polymer from europium(iii) carbonate hemioxalate hydrate

“…The origin of the carbonate ions is unclear at present, but a degradation product from an ox anion or atmospheric carbon dioxide would supposedly be a carbonate source. [30][31][32][33][34] It seems to be relatively rare that carbonate salts were prepared under mildly acidic conditions. An apparatus like a sealed bomb may be responsible for the trapping of volatile carbon dioxide within a crystal.…”

“…There have been several reports on CO 2 fixation to coordination compounds. [30][31][32][33][34] The present reaction can be regarded as a rare example where CO 2 was incorporated into a crystal under acidic reaction conditions. Such properties attract much attention for reducing greenhouse gases.…”