Coaggregation of Paramagnetic d- and f-Block Metal Ions with a Podand-Framework Amine Phenol Ligand

Abstract

This report covers initial studies in the coaggregation of nickel (Ni2+) and lanthanide (Ln3+) metal ions to form complexes with interesting structural and magnetic properties. The tripodal amine phenol ligand H3tam (1,1,1-tris(((2-hydroxybenzyl)amino)methyl)ethane) is shown to be particularly accommodating with respect to the geometric constraints of both transition and lanthanide metal ions, forming isolable complexes with both of these ion types. In the solid-state structure of [Ni(H2tam)(CH3CN)]PF6.2.5CH3CN.0.5CH3OH (1), the Ni(II) center has a distorted octahedral geometry, with an N3O2 donor set from the [H2tam]- ligand and a coordinated solvent (acetonitrile) occupying the sixth site. The reaction of stoichiometric amounts of H3tam with the Ni(II) ion in the presence of lanthanide(III) ions provides [LnNi2(tam)2]+ cationic complexes which contain coaggregated metal ions. These complexes are isolable and have been characterized by a variety of analytical techniques, with mass spectrometry proving to be particularly diagnostic. The solid-state structures of [LaNi2(tam)2(CH3OH)1/2(CH3CH2OH)1/2(H2O)]ClO4.0.5CH3OH.0.5CH3CH2OH.4H2O (2), [DyNi2(tam)2(CH3OH)(H2O)]ClO4.CH3OH. H2O(6), and [YbNi2(tam)2(H2O)]ClO4.2.58H2O(9) have been determined. Each complex contains two octahedral Ni(II) ions, each of which is encapsulated by the ligand tam3- in an N3O3 coordination sphere; each [Ni(tam)]-unit caps the lanthanide(III) ion via bridging phenoxy oxygen donor atoms. In 2, La3+ is eight-coordinated, while in 6, Dy(III) is seven- (to "weakly eight-") coordinated, and Yb(III) in 9 has a six-coordination environment. The complexes are symmetrically different, 2 possessing C2 symmetry and 6 and 9 having C1 symmetry. Magnetic studies of 2, 6, and 9 indicate that antiferromagnetic exchange coupling between the Ni(II) and Ln(III) ions increases with decreasing ionic radius of Ln(III).

Trinuclear NiII-LnIII-NiII Complexes with Schiff Base Ligands: Synthesis, Structure, and Magnetic Properties

“…3 ) 2 Ln](NO 3 ) (HL 6 = (Z)-2-methoxy-6-((phenylimino)methyl)phenol, Ln III = La, Pr, Gd, Tb) [17,18], and [{Ni{L 7 ) 1.5 } 2 Ln(OH)] (H 2 L 7 = 7,7 -(ethane-1,1-diyl)bis(quinolin-8-ol), Ln III = Eu, Tb, Gd) [19] Each of the terminal Ni II ions in the above complexes [11][12][13][14][15][16][17][18][19][20][21][22][23][24] is coordinated to three phenolato oxygen atoms and three nitrogen atoms, consisting of in situ formed (NiL) − metalloligand. The coordination geometry around the Ni II ions is distorted octahedral except in the case of [{Ni{L 7 ) 1.5 } 2 Ln(OH)] [19] in which the N 3 O 3 atoms create a regular trigonal-antiprismatic geometry around the Ni II ions.…”

A Four‐Shell, Nesting Doll‐like 3d–4f Cluster Containing 108 Metal Ions

“…[5,6] Particular interest in this field has been directed towards heterometallic complexes that feature both d-and f-block elements, and the distinct coordination behaviors of different metal ions have been observed in a large number of stunningly beautiful complexes. [7][8][9][10][11][12][13][14][15][16][17] The unique arrangement of the multiple metal centers within the complex framework, coupled with their inherently disparate electronic structures, often leads to attractive properties, of which novel magnetic phenomena such as single-molecule [14,15] and single-chain magnetism [16,17] are arguably the most notable.Our own efforts along this line of research have resulted in a number of giant 3d-4f clusters containing up to 50 metal ions. [18,19] These clusters display both stunningly beautiful structures and magnetic behaviors ranging from ferromagnetic to antiferromagnetic couplings.…”

Carbonato-bridged heteronuclear NiII2LnIII2 (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu) complexes synthesized by fixation of atmospheric CO2 – Structural and magnetic studies

“….Ni1 * distance in the tetranuclear unit (about 8.2 Å). The same kind of weak interaction is also observed for several compounds containing diamagnetic lanthanide(III) centers capable of mediating magnetic exchange between the nickel(II) ions [4,17,28,29,67]. Nevertheless, it is worth adding that the given values of J should be taken with caution as even the presence of a very weak anisotropy of Ni II ion can enhance artificially its estimation.…”