Praseodymium , crystal structure

In the crystal structure of Pr2ls there are two crystallographically independent praseodymium sites, Prl and Pr2, which have coordination numbers of 7 and 8 with mean Pr-I distances of 322.0 and 335.3 pm, respectively [19]. These distances are much like the respective Pr-I distances for coordination number 7 in K2PrIs (d= 321.2 pm [20]) and are as expected for coordination number 8 in... 

The Sr-doped praseodymium manganites and cobaltites have been studied by several groups as potential cathodes for ITSOFC. Kostogloudis et al. [116-118] systematically investigated the crystal structure, electrical conductivity, and thermal expansion properties of (Pr, Sr)Mn03, (Pr, Sr)Co03, and (Pr, Sr)(Co, Mn)03 systems. All compounds have the orthorhombic perovskite GdFe03-type structure (Pbnm... 

Recently we have reported the analysis of crystal structures of single crystals of DyMnOj [3] and LnMnOj (Ln = Nd, Sm, Eu and Gd) [4] using a four cycle X-ray diffractometer. In this study the growth of single crystals of PrMnOj and TbMnOj and the refined crystal structures are described. Since praseodymium and terbium have several valence states, some considerations about the atmospheric conditions are necessary. 

Figure 3.11 Structures of (a) [Sm2L6(MeOH)4] (HL = benzoic acid) and (b) [Pt2L6(H20)3] (HL = acetic acid) [RE, black O, grey C, white H, omitted]. (Redrawn from the CIF files of U.R Singh, R. Kumar and S. Upreti, Synthesis, structural, photophysical and thermal studies of benzoate bridged Sm(III) complexes, Journal of Molecular Structure, 831 (1-3), 97-105, 2007 [56] and D. Deiters and G. Meyer, Synthesis and crystal structure of praseodymium propionate trihydrate, Pr(CH3CH2C00)3(H20)3, Zeitschrift filr Anorganische und Allgemeine Chemie, 622 (2), 325-328, 1996 [57].)...

Deiters, D. and Meyer, G. (1996) Synthesis and crystal structure of praseodymium propionate trihydrate, Pr(CH3CH2C00)3(H20)3. Zeitschrift filr Anorganische und Allgemeine Chemie, 622 (2), 325-328. 

Figure 4.17 The structure of [Pr(16)6] [33]. (Reproduced with permission from A. Clearfield, R. Gopal and R.W. Olsen, Crystal structure of hexakis(l,8-naphthyridine)praseodymium(III) perchlorate, Inorganic Chemistry, 16, 911, 1977. 1977 American Chemical Society.)...

Praseodymium and neodymium built almost identical structures with myo-inositol. In the crystal structures of [Pr(myo-Ins)]Cl3 9 H2O [100] and [Nd(myo-Ins)]Cl3 9 H2O [101], by triva-lent lanthanide cations complexed myo-inositol, each Pr or Nb is coordinated to nine oxygen atoms, two from the inositol (two adjacent hydroxyl groups) and seven from water molecules... 

Lanthanide complexes with optically active -diketones have been used to determine the purity of optical isomers see chap. 4, p. 87 of Ref. 2 for a review). The most widely used chiral shift reagents are based on 3-trifiuoroacetyl-d-camphor, the anion of which is designated facam. The crystal structure determination of the DMF adduct of tris(3-tri-fiuoroacetyl-d-camphorato) praseodymium (III), the first of a chiral shift reagent, has been completed (31). The asymmetric unit contains the dimer, (facam)sPr(DMF)3Pr(facam)3, with the DMF oxygen atoms forming bridges between the two Pr(facam)3 moieties. Therefore, each Pr(III) ion is nine-coordinate with a geometry best described as a capped... 

The formation and crystal structure of the PrFeaGea (2) compoimd was reported in an early investigation of praseodymium-iron-germanium combinations by Rossi et al. (1978a,b) CeGaaAla type, a = 0.4055, c= 1.0540 was later confirmed by Bara et al. (1990), a = 0.4060, c=1.0508. For sample preparation, see LaMn2Gc2 under La-Mn-Ge, and LaFc2Ge2 under La-Fe-Ge, respectively. 

The phase diagram for the Pr—Ru-Ge system is not available yet, however several groups of authors investigated praseodymium-ruthenium-gemianium combinations with respect to the formation and crystal structure of the compounds. 

The crystal structure of the compound PrPd2Ge was found to be of the YPd2Si type (a = 0.7617, 6 = 0.6993, c = 0.5735 X-ray powder diffraction) by Jorda et al. (1983). The sample was obtained by induction melting under an argon atmosphere and armealing in evacuated quartz tube for 10 days at 1173 K. The starting materials were palladium (4N), germanium (4N), praseodymium (3N). 

Key words Crystal structure, lanthanides, praseodymium, dimer, macrocycle, (2.2.1), cryptand, NMR, paramagnetic ion. 

The crystal structure of the rare earth oxyorthosUicates has been determined from single crystals prepared using Bi203 as a flux material (Buisson and Michel, 1968). The oxyorthosilicates from praseodymium to terbium are isomorphic and crystallize in the monocUnic space group P2 /c with Z = 4. According to Ananeva et al. (1981) dysprosium can also have this structure type (A) too, but more often has another structure type (B). It is not clear whether or not lanthanum has a structure of its own. The unit cell dimensions of lanthanide oxyorthosilicates, except those of cerium and promethium compounds, are presented in table 9. 

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