Solution and solid state structures and magnetism of a series of linear trinuclear compounds with a hexacoordinate Ln^III and two terminal Ni^II centers

Abstract

Reported are the syntheses, structures and magnetic properties, also by NMR spectroscopy in solution, of a series of 13 linear trinuclear 3d-4f compounds with a lanthanide(iii) surrounded by two Ni ions, NiLn, where the central Ln is hexacoordinate. For three of the crystal structures, an additional HO molecule is coordinated to the central Ln ion, leading to a monocapped trigonal prismatic structure. However, NMR spectroscopy indicates that in solution, these complexes also have a hexacoordinate Ln center. The solution magnetic anisotropies, determined by NMR spectroscopy, indicate that the axial components of the anisotropies are relatively small and that the Dy derivative might therefore not exhibit single molecule magnetism. The axial anisotropies determined by NMR spectroscopy are in good agreement with the expectations based on the distorted trigonal prismatic ligand field.

Bimetallic nickel-lutetium complexes: tuning the properties and catalytic hydrogenation activity of the Ni site by varying the Lu coordination environment

“…Complexes 3 , 3-THF , and 4 join a handful of crystallographically characterized compounds containing both Ni and Lu metals. Among these examples, the intermetal distances are too large to allow for any significant metal–metal interactions 44–50. Hence, without sufficient experimental comparisons to evaluate and/or interpret our Ni–Lu bond distances, we considered several different approaches for estimating a single bond length that is based on summing the two atoms' radii.…”

“…If one accounts for the single-bond covalent radius difference between Lu (1.62 Å) and U (1.70 Å), then 3 and NiUF(2-PPh 2 -4-Me-6- t Bu(C 6 H 2 O)) 3 have similar r values of 0.91 and 0.90, respectively, where r is the ratio of their metal–metal bond distance to the corresponding sum of the metals' single-bond radii 51. Also, only a handful of Lu-group 10 compounds have been reported that have intermetal distances < 3 Å 15,44,56,57. These limited examples include (C 5 Me 4 SiMe 2 CH 2 PPh 2 )Lu(μ-CH 2 SiMe 2 CH 2 )(OC 4 H 8 )PtMe 2 and [(Ph 2 PNHPh)M{μ-(Ph 2 PNPh)} 3 Lu(μ-Cl)Li(THF) 3 ] (M = Pd or Pt), where the intermetallic distances are longer at 2.7668(5) Å, 2.9031(11), and 2.9523(9), respectively.…”

Supramolecular Approach for Enhancing Single‐Molecule Magnet Properties of Terbium(III)‐Phthalocyaninato Double‐Decker Complexes with Crown Moieties

“…To confirm the structural changes induced by the addition of alkali metal ions, NMR spectroscopy was employed. A detailed introduction to NMR spectroscopy of paramagnetic complexes is given in our previous works and elsewhere . In the case of Ln complexes with diamagnetic ligands, the pseudocontact shift ( pcs ), which originates form magnetic dipole–dipole interactions between unpaired f electrons and nuclear spins, is the dominant contribution to the hyperfine shift.…”

“…Ad etailed introduction to NMR spectroscopy of paramagnetic complexes is given in our previous works and elsewhere. [54][55][56][57][58][59][60][61] In the case of Ln complexesw ith diamagnetic ligands, the pseudocontact shift (pcs), which originates form magnetic dipole-dipolei nteractions betweenu npaired fe lectrons and nuclear spins, is the dominant contribution to the hyperfine shift. For Ln complexes with axial symmetry, pcs is expressed by Equation (1) (point dipole approximation), in which c ax is the axial component of the magnetic susceptibility tensor, r is the lengtho fv ector which connects the nucleusa nd the unpaired electrons and q is the angle between the vector r and the magnetic easy axis.…”

Correlation of Structural and Magnetic Properties in a Set of Mononuclear Lanthanide Complexes

“…We have reported both homodinuclear lanthanide(III) and heterodinuclear 3d–4f systems, combining our computed values with alternating and direct current (ac and dc) SQUID, high frequency EPR (HF‐EPR), and magnetic circular dichroism (MCD) data, including extensive ligand field analysis based on angular overlap model (AOM) calculations ,. More recently we have utilized paramagnetic NMR spectroscopy and SQUID measurements to determine the solution and solid‐state magnetic behavior of a series of linear trinuclear Ni II 2 Ln III complexes with Ln=Y, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu . Additionally, single crystal dc SQUID and HF‐EPR data of the Ln=Dy complex has provided further validation of our ab initio calculated data…”