Home About us Contact
|
Home About us Contact | ||
|
|
||
Lanthanide Contraction (lanthanide + contraction)
Selected AbstractsLanthanide Complexes of Disulfoxide Ligands with Varied Configurations: Influence of Lanthanide Contraction on the Structures of the ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2005Jian-Rong Li Abstract Four new disulfoxide-LnIII complexes, [Ln(L)2(NO3)3]n {Ln = La (1), n = n; Ln = Gd (2), Dy (3) and Yb (4), n = 2}, have been prepared by the reaction of Ln(NO3)3·nH2O with meso -1,3-bis(ethylsulfinyl)propane (meso - L) in methanol/triethylorthoformate, and their solid-state structures were characterized by IR spectroscopy, elemental analyses and X-ray diffraction. Complex 1 is a 1D double-bridged chain in which the LaIII ions are ten-coordinate and the L ligands adopt both meso and rac configurations, and a bis-monodentate bridging coordination mode. While complexes 2,4 have isostructural dinuclear structures, in which the LnIII ions are nine-coordinate and the ligands show two types of coordination fashions and configurations: bis-monodentate bridging with a meso -configuration, and monodentate coordination with a rac -configuration. The structural differences between 1 and 2,4 indicate the influence of lanthanide contraction on the complex structures. In addition, a change in configuration of the ligand occurs when it reacts with metal ions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Comparative Electrochemical Study of Unsubstituted and Substituted Bis(phthalocyaninato) Rare Earth(III) ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2004Peihua Zhu Abstract The electrochemistry of homoleptic substituted phthalocyaninato rare earth double-decker complexes M(TBPc)2 and M(OOPc)2 [M = Y, La...Lu except Pm; H2TBPc = 3(4),12(13),21(22),30(31)-tetra- tert -butylphthalocyanine, H2OOPc = 3,4,12,13,21,22,30,31-octakis(octyloxy)phthalocyanine] has been comparatively studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in CH2Cl2 containing 0.1 M tetra- n -butylammonium perchlorate (TBAP). Two quasi-reversible one-electron oxidations and three or four quasi-reversible one-electron reductions have been revealed for these neutral double-deckers of two series of substituted complexes, respectively. For comparison, unsubstituted bis(phthalocyaninato) rare earth analogues M(Pc)2 (M = Y, La...Lu except Pm; H2Pc = phthalocyanine) have also been electrochemically investigated. Two quasi-reversible one-electron oxidations and up to five quasi-reversible one-electron reductions have been revealed for these neutral double-decker compounds. The three bis(phthalocyaninato)cerium compounds display one cerium-centered redox wave between the first ligand-based oxidation and reduction. The half-wave potentials of the first and second oxidations and first reduction for double-deckers of the tervalent rare earths depend on the size of the metal center. The difference between the redox potentials of the second and third reductions for MIII(Pc)2, which represents the potential difference between the first oxidation and first reduction of [MIII(Pc)2],, lies in the range 1.08,1.37 V and also gradually diminishes along with the lanthanide contraction, indicating enhanced ,,, interactions in the double-deckers connected by the smaller, lanthanides. This corresponds well with the red-shift of the lowest energy band observed in the electronic absorption spectra of reduced double-decker [MIII(Pc,)2], (Pc, = Pc, TBPc, OOPc). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Soft X-ray photoemission spectroscopy of (LnO)CuS (Ln=Ce, Pr, Nd)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006H. Sato Abstract Soft x-ray photoemission spectroscopy for layered oxysulfides (LnO)CuS (Ln = Ce, Pr, Nd) has been curried out in the Ln 3d-4f absorption region, to deduce the Ln 4f partial densities of states (DOSs). Only the Ce 4f DOS contributes to the valence-band maximum of (CeO)CuS, and on going from Ln = Ce to Pr, and to Nd, the 4f DOS shifts toward the deeper binding-energy side due to the lanthanide contraction. The Ce 3d photoemission spectrum of (CeO)CuS shows the mixing of Ce3+ and Ce4+ in the ground state. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Three-Dimensional Lanthanide(III),Copper(II) Compounds Based on an Unsymmetrical 2-Pyridylphosphonate Ligand: An Experimental and Theoretical StudyCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2007Yun-Sheng Ma Abstract Based on an unsymmetrical 2-pyridylphosphonate ligand, two types of LnIII,CuII compounds with three-dimensional structures were obtained under hydrothermal conditions, namely, Ln2Cu3(C5H4NPO3)6,4,H2O (1,Ln; Ln=La, Ce, Pr, Nd) and Ln2Cu3(C5H4NPO3)6 (2,Ln; Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho). Compounds 1,Ln are isostructural and crystallize in chiral cubic space group I213. In these structures, each Ln ion is nine-coordinate and has a tricapped triprismatic geometry, while each Cu center is six-coordinate with an octahedral environment. The {LnO9} polyhedra and {CuN2O4} octahedra are connected by edge sharing to form an inorganic open framework structure with a 3-connected 10-gon (10,3) topology in which the Ln and Cu atoms are alternately linked by the phosphonate oxygen atoms. Compounds 2,Ln are isostructural and crystallize in trigonal space group R. In these structures, the {LnO6} octahedra are triply bridged by the {CPO3} tetrahedra by corner sharing to form an infinite chain along the c axis. Each chain is connected to its six equivalents through corner sharing of {CPO3} tetrahedra and {CuN2O2} planes to form a three-dimensional framework structure in which the Ln and Cu atoms are linked purely by O-P-O units. The formation of these two types of structures is rationalized by quantum chemical calculations, which showed that both the lanthanide contraction and the electron configuration of CuII play important roles. When CuII was replaced by ZnII, only the first type of compounds resulted. The magnetic properties of complexes 1,Ln and 2,Ln were investigated. The nature of LnIII,CuII (Ln=Ce, Pr, Nd) interactions is illustrated by comparison with their LnIII,ZnII analogues. [source] | ||||||||||