Lanthanide complex with tris

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. 

Dimerization of phenyl isocyanate, catalyzed by lanthanide complexes, has been reported by Deng et al. <2003CHJ574>. A number of lanthanide complexes were tried and Sm(SPh)3(hmpa)3 was found to be the most effective catalyst. Conversion was as high as 96% with 2500 1 of substrate to catalyst ratio (Scheme 47). 

Tris(cyclopentadienyl)lanthanide complexes with steri-cally more crowded Cp ligands such as C5Me4R (R = Me, Et, Tr, and SiMe3) are not assessable by simple metathesis between lanthanide trihalides and the respective alkali metal salt of the bulky Cp ligand. For instance, Cp 3Sm, obtainable from Cp 2Sm and cyclooctatetraene, reacts with THF with ring-opening forming Cp 2Sm[0(CH2)4Cp ](THF) (equation 14). 

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... 

Nine-coordinate lanthanide complexes with /3-diketones having the compositions of Ln(/3-diketonate)4(sol) andLn(/3-diketonate)3(L)(sol)3 (L = N,N,N-tridentate ligand, X = 0 L = N,N,-bidentate ligand, x = 1), have recently been stmcturally characterized. The molecular stmcture of Eu(L )3(TPTZ) (TPTZ = 2,4,6-tri(2-pyridyl)-l,3,5-triazine) isis shown in Figure 14. The lanthanide ion in each of... 

The ions Sm+, Eu+, Tm+, and Yb+ form addition complexes with 1,3,5-tri-ferf-butylbenzene (130), whereas other lanthanide ions form dehydrogenation products (see Section III.A.2). 

A number of methyl substituted PyO have been tried as ligands for coordination with the lanthanides. Depending on the position of the substituent, these ligands impart different degrees of steric strain for the formation of complexes. Since substituents in the 4 or 3 position do not introduce substantial steric hindrance to coordination, Harrison and Watson (160) could synthesize octakis-4-MePyO complexes. Subsequently, Koppikar and Soundararajan (161) could also synthesize octakis-3-MePyO complexes with lanthanide perchlorates. Complexes of 4-MePyO (162, 163) and 3-MePyO (164, 165) with lanthanide iodides and bromides also have a L M of 8 1. 

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. 

Recently, tris-p-diketiminate lanthanide complexes [LnL3 ] (X = Cl, L Ln = Pr 111, Nd 112, Sm 113 X = H, L Ln = Nd 114 X = Me, L Ln = Nd 115) (Scheme 12) displaying a high activity in producing PLAs under mild conditions via ROP of L-lactide have been reported. This reactivity may be attributed to the crowded coordination sphere around the central metal, which incidentally affords an activated Ln-N(p-diketiminate) bond. The activity depends on the central metals, and the active trend of Sm < Nd < Pr is consistent with the sequence of the ionic radii [113]. 

The very useful lanthanide shift reagents, which facilitate analysis of molecular stereochemistry because of their line-broadening characteristics in NMR spectra, were studied when bound as a chelate complex to thietanes. X-Ray analysis of the adduct 3,3-dimethylthietane 1-oxide with tris(dipivalo-methanato)europium(III) [Eu(dpm)3] revealed the structure of a seven-coordinate complex (271). ... 

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