Anomalous scattering by praseodymium, samarium and gadolinium and structures of their ethylenediaminetetraacetate (edta) salts

Abstract

terms f" derived for this wavelength are 2.87 (11), 3.64 (10), and 3.91 (9) e atom -1 respectively for Pr, Sm and Gd, in good agreement with theoretical values.

Edta-linked 5p–4f trinuclear heterometallic complex: syntheses, X-ray structure and luminescent properties

“…(14) , respectively, similar to those in the related Sb-edta complexes [21]. As shown in figure 2, the coordination polyhedron around each samarium is a distorted square antiprism with four sites occupied by four oxygen atoms from coordinated water molecules (O(17), O (18), O (19), and O (20)) and four sites occupied (13) , similar to those in the related Sm(III) complexes [21][22][23]. Generally, lanthanide(III) metal complexes with aminopolycarboxylic acids adopt eight-, nine-, or 10-coordinate structures.…”

“…In 1, the bidentate chelating bond distances (Sb (1) (2) (12) Symmetry transformations used to generate equivalent atoms: #1 x þ 1/2, Ày, z þ 1/2; #2 x À 1/2, Ày þ 1, z þ 1/2. (14) , respectively, similar to those in the related Sb-edta complexes [21]. As shown in figure 2, the coordination polyhedron around each samarium is a distorted square antiprism with four sites occupied by four oxygen atoms from coordinated water molecules (O(17), O (18), O (19), and O (20)) and four sites occupied (13) , similar to those in the related Sm(III) complexes [21][22][23].…”

Effect of the formation of EDTA complexes on the diffusion of metal ions in water

“…This is again due to the more compact form of M-EDTA (zÀ4)+ for the ion with a larger ionic potential due to the larger attractive force between EDTA and metal ion. It was shown for Ln 3+ that the average bond length of Ln and neighboring atoms in EDTA complexes decreases from La 3+ to Yb 3+ (Table 4; Hoard et al, 1965;Nassimbeni et al, 1979;Templeton et al, 1982Templeton et al, , 1985Nakamura et al, 1995;Sakagami et al, 1999), which results in the increase of D Ln-EDTA from lighter to heavier Ln. In addition, the difference between D Ln and D Ln-EDTA becomes small from La 3+ to Lu 3+ , where D Ln-EDTA nearly coincides to D Ln for heavier Ln.…”

“…Normally, EDTA is a hexadentate ligand, and the structure of the EDTA complex with metal ion having six coordination numbers may be structurally most compact, since all functional groups of EDTA can coordinate to the metal ion. In the case of metal ion with coordination numbers above 6 such as Ln 3+ , the structure of the EDTA complex may become larger, since a few water molecules coordinated to the metal ion in addition to EDTA (Hoard et al, 1965;Nassimbeni et al, 1979;Templeton et al, 1982Templeton et al, , 1985Nakamura et al, 1995;Sakagami et al, 1999). These speculations imply that the difference in coordination number has a large effect on the diffusion coefficients of M-EDTA (zÀ4)+ for metal ions, but the effect of hydration of the EDTA complex is minimal, which is different from free metal ions.…”

Well-defined lanthanum ethylenediaminetetraacetates as the precursors of catalysts for the oxidative coupling of methane

“…On account of the high affinity to hard donor atoms of lanthanides, aminopolycarboxylates are widely exploited for their capability of bridging metal centers in various coordination modes [18][19][20][21]. However, as a widely used multidentate ligand, ethylenediaminetetraacetic acid shows limited coordination modes with lanthanides, such as a mononuclear or oligomer species Ln(edta)ÁnH 2 O or MLn(edta)ÁnH 2 O (M = Na, K, Ln = La, Ce, Pr, Nd, Sm, Er) [22][23][24][25], Na 2 K 2 [Ce 2 (O 2 ) 2 (edta) 2 ]Á13H 2 O [26], Na 10 [La 4 (l 3 -OH) 4 (edta) 4 ]Á 2ClO 4 Á27H 2 O [27]. Most of the insoluble coordination polymers are formed in hydrothermal condition with general formula {[Ln(Hedta)(H 2 O)] 2 } n (Ln = La, Nd, Sm, Er) [28][29][30][31], and one [Ce 3 (Hedta) 2 (H 2 O) 9 ] n [Cr(OH) 6 Mo 6 O 18 ] n ÁnH 2 O was reported [32].…”