Lanthanide chloride complexes

Chaumont, A., Wipff, G. (2004), M3+ Lanthanide Chloride Complexes in "Neutral" Room-Temperature Ionic Liquids. A Theoretical Study, J. Phys. Chem A 108, 3311-3319. 

Question 43 A summary of stmcture types in the lanthanide chloride complexes of THE is given in Table 4.3 (databased upon G.B. Deacon, T. Feng, PC. Junk, B.W. Skelton, A.N. Sobolev and A.H. White, Aust. J. Chem., 1998, 51,75). 

The synthesis and characterization of the first bis- and tris[ 1 -(tu-alken-l-yl)indenyl] lanthanide complexes (Ln = Gd, Er, Y, Lu) have been reported. l-Allyl-2,4,7-trimethyl-lFI-indene and l-(3-buten-l-yl)-4,7-dimethyl-lH-indene were prepared from (2,4,7-trimethylindenyl)lithium and allyl chloride or from (4,7-dimethylindenyl)lithium and 4-bromo-l -butene.677 The reactions of the trichlorides of gadolinium, erbium, yttrium, lutetium, and ytterbium in molar ratios in TFIF produce the bis(l-allyl-2,4,7-trimethylindenyl)lanthanide chloride complexes L2LnCl(THF) (Ln = Gd, Er), bis( 1 -buten-1-yM,7-dimcthyIindcnyI)lanthanide complexes (Ln = Y, Lu) or the heterometallic complexes bis(l-buten-l-yl-4,7-dimethylindenyl)Yb(/r-Cl)2Li(THF)2 (Scheme 180).677... 

Lanthanides and Actinides. - Paramagnetic shifts were reported in the NMR spectra of trivalent lanthanide chloride complexes with bipy.1234... 

Most lanthanide compounds are sparingly soluble. Among those that are analytically important are the hydroxides, oxides, fluorides, oxalates, phosphates, complex cyanides, 8-hydroxyquinolates, and cup-ferrates. The solubility of the lanthanide hydroxides, their solubility products, and the pH at which they precipitate, are given in Table 2. As the atomic number increases (and ionic radius decreases), the lanthanide hydroxides become progressively less soluble and precipitate from more acidic solutions. The most common water-soluble salts are the lanthanide chlorides, nitrates, acetates, and sulfates. The solubilities of some of the chlorides and sulfates are also given in Table 2. 

Moeller and Vicentini (48) have reported the complexes of DMA with lanthanide perchlorates in which the number of DMA molecules per metal ion decreases from eight for La(III)—Nd(III) to six for Tm(III)—Lu(III).apparently due to the decrease in the cationic size. The complexes of the intermediate metal ions have seven molecules of DMA in their composition. Complexes of lanthanide chlorides with DMA (49, 50) exhibit a decrease in L M from 4 1 to 3 1 through 3.5 1. These complexes probably have bridging DMA molecules. The corresponding complexes with lanthanide iodides (51), isothiocyanates (52), hexafluorophosphates (57), nitrates (54, 55), and perrhenates (49, 56) also show decreasing L M with decreasing size of the lanthanide ion. However, complexes of DMA with lanthanide bromides (55) do not show such a trend. Krishnamurthy and Soundararajan (41) have reported the complexes of DPF with lanthanide perchlorates of the composition [Ln(DPF)6]... 

A number of complexes of urea and substituted ureas with various lanthanide salts have been isolated. The lanthanide acetates give both anhydrous and hydrated complexes with urea (67, 68). The hydrated complexes could be dehydrated by drying the complexes over CaCl2 or P4Oi0 (68). It is interesting to note that in the complexes of substituted ureas like EU (70) and CPU (71), the L M is independent of the anion. The anions in these complexes with a L M of 8 1 are apparently nonco-ordinated. Seminara et al. (72) have reported complexes of lanthanide chlorides with DMU and DEU which contain five and three molecules of the ligand respectively per... 

With the lanthanide chlorides, tris-DMP complexes were obtained (99) in which all the chlorides are supposed to be coordinated. 

Oximes can act both as anionic and neutral ligands. Complexes of Box (134), DBox (135), Fox (136), BMox (137) and DAMox (138) with lanthanide chlorides have been reported. These oximes act as bidentate ligands coordinating through the oxygen of the C=0 or the C-O—H group and the oxime group. 

By changing the method of preparation, complexes of the formula Ln(Py0)3(N03)3, in which all the nitrates are coordinated to the lanthanide ion in a bidentate fashion, could be prepared (152). PyO yields complexes with lanthanide chlorides (156), bromides (156), iodides (157) and hexathiocyanatochromate (159) all of which have a L M of 8 1. However, by changing the synthetic procedure, Sivapullaiah and Soundararajan (158) could prepare complexes of the formula [Ln(PyO)6 Br2(H20)2]Br... 

Substitution at the 2-position of the pyridine ring in PyO introduces steric hindrance to coordination as is evident from the formation of Heptakis-2-MePyO complexes with lanthanide perchlorates (167) and pentakis-2-MePyO complexes with the corresponding bromides (168), iodides (162) and chlorides (169). The lanthanide nitrate complexes prepared by Ramakrishnan and Soundararajan (170) have the formula Ln(2-MePy0)3(N03)3 -xH20in which all the nitrate groups are bidentate. 

Complexes of lanthanide chlorides 156,173), bromides (256), and iodides 174) with 2,6-DMePyO have also been prepared and characterized. The presence of bridging 2,6- DMePyO molecules has been suggested in the complexes of lanthanide iodides. Vicentini and De Oliveira (2 73) have reported tetrakis-2,6-DMePyO complexes with lanthanide nitrates. However, by changing the method of synthesis, tris-2,6-DMePyO complexes with the lanthanide nitrates could be prepared in this laboratory (252). All the nitrate groups in the tris-2,6-DMePyO complexes are bidentate. In the 2,4,6-TMePyO complexes (252) also the nitrate groups are coordinated to the lanthanide ion in a bidentate fashion. 

Complexes of PyzO with lanthanide perchlorates (2 79) and hexafluorophosphates 180) are eight coordinate. However, La(III) perchlorate gives the complex La(Pyz0)7(C104)3 2 H20 in which both the water molecules are coordinated to La(III). In the case of complexes of PyzO with lanthanide chlorides 180), the number of coordinated ligands increases as the ionic radius of the lanthanide ion decreases. These complexes probably contain bridging ligands. 

Since 1972, complexes of lanthanides with cyclic sulfoxides have received considerable attention. Zinner and Vicentini (261) have reported the complexes of lanthanide perchlorates with TMSO. The L M in these complexes decreases along the lanthanide series. But in the case of complexes of lanthanide chlorides with TMSO, the L M increases from 2 1 for the lighter lanthanides to 3 1 for the heavier lanthanides (262). It has been suggested that these complexes, especially the bis-TMSO complexes, contain bridging chloride ions. Tetrakis-TMSO complexes with lanthanide isothiocyanates have also been reported (263). 

In the complexes of TBPO with lanthanide perchlorates, absorptions at 400 cm-1 have been ascribed to i>Ln o (210). Absorptions due to lanthanide-perchlorate vibrations (Ln—OC103) have been identified in the region 290—360 cm-1 for the complexes of lanthanide perchlorates with 2,6-DMePyO (171), TBPO (210), DMMP (210), and for the complexes of Ce(III) perchlorate with TPPO and TBPO (206, 211). Ln-Cl vibrations occur at 230 cm-1 in the complexes of lanthanide chlorides with TBP (195) and TPPO (202). In the complexes of lanthanide bromides with TBP (295), i Ln— Br occurs in the region of 195 cm-1. 

The anions in the complexes of DMSO and DMF with lanthanide chlorides are coordinated (43, 252). In DMF both these series of complexes behave as 1 1 electrolytes showing the presence of one replaceable chloride ion. This chloride is probably weakly bound compared to the other two chloride ions. These results were explained by assuming the presence of bridging chloride ions in these complexes. Results obtained for the complexes of TMSO with lanthanide chlorides have been explained in a similar fashion (262). 

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