Lanthanide complexes crystal structure

The light lanthanides received new emphasis in the 1970s with the availability of sizeable single crystals. These metals presented many more difficulties in understanding because of their complex crystal structure and the much weaker exchange relative to the crystal-field energies. 

However, the Fermi surface depends sensitively on details of the E-k relation, and the determination of the Fermi surface demands a more precise calculation for the eigenvalues than that for the cohesive energy. Therefore, for studies of the Fermi surface, these linearized methods should be applied carefully. Errors originating from linearized approximations should be minimized. Nevertheless, the LAPW method is valuable for calculations of the electronic structure in lanthanide compounds with complex crystal structures, such as LaCufi. 

In a similar manner, treatment of anhydrous rare-earth chlorides with 3 equivalents of lithium 1,3-di-ferf-butylacetamidinate (prepared in situ from di-ferf-butylcarbodiimide and methyllithium) in THF at room temperature afforded LnlMeCfNBuOils (Ln = Y, La, Ce, Nd, Eu, Er, Lu) in 57-72% isolated yields. X-ray crystal structures of these complexes demonstrated monomeric formulations with distorted octahedral geometry about the lanthanide(III) ions (Figure 20, Ln = La). The new complexes are thermally stable at >300°C, and sublime... 

Reactions of UCI4 with [Li RC(NCy)2 (THF)]2 (R = Me, Bu ) in THF gave the tris(amidinate) compounds [RC(NCy)2]3UCl that could be reduced with lithium powder in THF to the dark-green homoleptic uranium(lll) complexes [RC(NCy)2]3U. Comparison of the crystal structure of [MeC(NCy)2]3U with those of the lanthanide analog showed that the average U-N distance is shorter than expected from a purely ionic bonding model. ... 

Probably, the first series of lanthanide complexes with neutral oxygen donor ligands is that of AP with the lanthanide nitrates. In 1913, Kolb (79) reported tris-AP complexes with lighter lanthanide nitrates and tetrakis-AP complexes with heavier lanthanide nitrates. Subsequently, complexes of lanthanide nitrates with AP which have a L M of 6 1 and 3 1 have also been prepared (80-82). Bhandary et al. (83) have recently shown through an X-ray crystal and molecular structure study of Nd(AP)3(N03)3 that all the nitrates are bidentate and hence the coordination number for Nd(III) is nine in this complex. Complexes of AP with lanthanide perchlorates (81, 84), iodides (81, 85), and isothiocyanates (66, 86, 87) are known. While the perchlorates and iodides in the respective complexes remain ionic, two of the isothiocyanates are coordinated in the corresponding complexes of AP with lanthanide isothiocyanates. 

Useful structural data have been obtained from single crystal X-ray diffraction methods for a number of lanthanide complexes (15,17). In this section, the structures of various complexes with neutral oxygen donor ligands which have been studied by single crystal X-ray diffraction methods are described. For convenience, the structures are discussed in terms of coordination numbers of the lanthanide ions. 

Radonovich and Click [156) in 1971 reported the crystal structure of Pr(terp)Cl3 8H2O complex, which they prepared by the original method of Sinha [157), for the preparation of mono-terpyridyl-lanthanide(III) chlorides, [M(terp)Cl3 wHaO], where terp =2,2, 2"-terpyridyl and has the following structure. When... 

Relatively few structural analysis of the decacoordinated lanthanide complexes have been reported. Although the lanthanides and actinides are long suspected as candidates for having decacoordination, it was not until 1965 that Lind, Lee and Hoard 211) were able to establish decacoordination for La(III) ion in monoclinic crystals of composition [La(EDTAH)] 7H2O. To date, only about ten or so decacoordinated structures are known, but many lanthanide complexes may have a coordination number of ten. 

Perchlorate ion complexes, 28 255-299 with cobalt group metals, 28 265-268 coordination types, 28 256-260 with copper group metals, 28 273-283 with early transition metals, 28 260-263 electronic spectra. 28 258-259 ESR spectra, 28 260 infrared and Raman spectra, 28 257-258 with iron group metals, 28 263-265 with lanthanides, 28 260-265, 287-288 magnetic susceptibility, 28 260 molar conductivities, 28 260 with nickel group metals. 28 268-273 X-ray crystal structure analysis, 28 256-257... 

Yang, X.-P. Su, C.-Y. Kang, .-S. Feng, X.-L. Xiao, W.-L. Liu, H.-Q. Studies on lanthanide complexes of the tripodal ligand bis(2-benzimidazolylmethyl)(2-pyridyl-methyl)amine. Crystal structures and luminescence properties. J. Chem. Soc., Dalton Trans. 2000, (19), 3253-3260. 

Reeves, Z. R. Mann, K. L. V. Jeffery, J. C. McCleverty, J. A. Ward, M. D. Barigelletti, F. Armaroli, N. Lanthanide complexes of a new sterically hindered potentially hexadentate podand ligand based on a tris(pyrazolyl)borate core crystal structures, solution structures and luminescence properties. J. Chem. Soc., Dalton Trans. 1999, 349-355. 

Dossing, A. Toftlund, H. Hazell, A. Bourassa, J. Ford, P. C. Crystal structure, luminescence and other properties of some lanthanide complexes of the polypyridine ligand 6,6,-bis[bis(2-pyridylmethyl)aminomethyl]-2,2,-bipyridine. J. Chem. Soc., Dalton Trans. 1997, (3), 335-339. 

Although they are not macrocyclic ligands, polyethyleneglycols behave somewhat similarly to the crown ethers regarding lanthanide complexation, as established by a number of crystal structure determinations. Thus a series of neodymium complexes shows consistent 10-coordination, namely [Nd(N03)3(tri-eg)],458 where tri-eg is triethyleneglycol, [Nd(N03)2(penta-eg)]N03,458 and [Nd(N03)2(N03)(tetra-eg)],459 where N03 is monodentate. The larger La3+ ion shows 11-coordination in [La(N03)3(tetra-eg)].460... 

It should be noted that definitive X-ray single crystal work is really needed on some of these compounds, as structures are often based on powder correlations with type structures of non-lanthanide complex fluorides, some of which are themselves quite early single crystal studies. 

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