Cerium complexes synthesis

Lithium(l) NHC adducts are extremely rare, but some examples have been isolated as stable crystalline solids when a ftmctional group is involved for their stabilization, the amino group, for instance. Since these showed to be effective in transmetallation processes, they represent an interesting alternative to the expensive silver complexes. As an example, Arnold reported the synthesis of covalently tethered lanthanide carbene complexes (214) using adduct (213) as source ofNHC (equation 39). Using (213) and the same methodology, unusual cerium complexes (215) and (216) were isolated and characterized (equation 40). ... 

Figure 4.26 Schematic representation of the synthesis of the double-decker bis(porphyrinato) cerium complexes from LiiPor and Ce(acac)3.

Kilimann, U., Herbst-Inmer, R., Stalke, D. et al. (1994) An efficient access to organocerium(lV) complexes synthesis and structure of bis[l,3,6-tris(trimethylsilyl)cyclooctatetraene]cerium(lV). Angewandte Chemie International Edition, 33, 1618. 

Evans, W.J., Deming, T.J., and Ziller, J.W. (1989) The utility of ceric ammonium nitrate-derived alkoxide complexes in the synthesis of organometallic cerium(lV) complexes. Synthesis and first X-ray crystallographic determination of a tetravalent cerium cyclopentadienide complex, (C5H5)3Ce(OCMe3). Organometallics, 8, 1581. 

Their cerium complex is reported as stable to air and acid (although decomposed by hot nitric acid), properties which are not consistent with those of the known bis([8]annulene)actinide(IV) complexes. The infrared spectrum of their complex is also inconsistent with the presence of a planar [8]annulene ligand. We have attempted to duplicate the synthesis of cerocene by the method of Kalsotra, Multani, and Jain and have not been able to reproduce their reported results. 

Within the cubane synthesis the initially produced cyclobutadiene moiety (see p. 329) is only stable as an iron(O) complex (M. Avram, 1964 G.F. Emerson, 1965 M.P. Cava, 1967). When this complex is destroyed by oxidation with cerium(lV) in the presence of a dienophilic quinone derivative, the cycloaddition takes place immediately. Irradiation leads to a further cyclobutane ring closure. The cubane synthesis also exemplifies another general approach to cyclobutane derivatives. This starts with cyclopentanone or cyclohexane-dione derivatives which are brominated and treated with strong base. A Favorskii rearrangement then leads to ring contraction (J.C. Barborak, 1966). 

The greater lability of 1-benzothiepin 1-oxides, compared to the parent compounds, may lead to differences in chemical behavior. Thus, treatment of the tricarbonyliron complex of 1-benzo-thiepin 1-oxide (8, X = SO) with ammonium cerium(IV) nitrate in acetone at — 30 °C leads, with the loss of sulfur monoxide, to naphthalene. In contrast, the iron ligand can be removed selectively from the corresponding 1-benzothiepin by ammonium cerium(IV) nitrate.23 92 For the synthesis of 1-benzothiepin 1-oxide, see Section 2.1.4.1,... 

The use of complex cerium nitrate (IV) (which is more accessible in comparison with (PyH)2CeCl6) in the synthesis of Ce(OR)4 piovedquite fruitful ... 

Trisubstituted (3-lactams have been reported to be obtained through oxidative removal of the /V-alkyl group from more complex (3-lactams by treatment with cerium ammonium nitrate [260], Anologous methodology was employed for a general synthesis of cis- and trans-(3-lactams bearing a quinone moiety at the N-l, the C-3, or the C-4 position (I, II and III, respectively, Fig. 8), [261]. 

Lanthanides in homogeneous systems As organometallics As cerium(IV) salts As coordination complexes As nitrates, chlorides, alkoxides etc. For olefin polymerization For olefin hydrogenation For free radical polymerization For Diels-Alder reactions For olefin polymerization In organic synthesis... 

Recent methods for the cleavage of allyl ethers that have that have yet to be tested on the anvil of complex target synthesis include (a) diborane generated in situ by reaction of sodium borohydride with iodine in THF at 0 °C (cyanoT ester, nitro, acetonide and tetrahydropyranyl groups survive) 434 (b) cerium(Ill) chloride and sodium iodide in refluxing acetonitrile (benzyl. THP and Boc groups survive) 435 (c) iodotrimethylsilane in acetonitrile at room temperature 436 and (d) DDO in wet dichloromethane (secondary allyl ethers, benzyl, acetate and TBS groups survive).437... 

It is a commonplace to say that there has been explosive growth in the use of lanthanides in organic chemistry. For many years, the use of cerium(iv) compounds as oxidants was widespread, but more recently a whole range of other compounds have made their appearance. Thus samarium(ii) compounds are now routinely used as one-electron reducing agents and the use of trifluoromethanesulfonate ( triflate ) salts of scandium and the lanthanides as water-soluble Lewis acid catalysts is widespread. Beta-diketonate complexes and alkoxides have also come into use there are even applications of mischmetal in organic synthesis. 

Figure 4.31 Synthesis of cerium (III) complexes of amino functionalised carbenes.

Gu and Soucek reported the synthesis of ceria nanoparticle in hydrocarbon solvents. Cerium-oleate complex was refluxed in high boiling point organic solvents such as octyl ether, 1-tetradecene, decalin, dipropylene glycol monomethyl ether, dipropylene glycol n-butyl ether, and 2,2,4-trimethyl-l,3-pentanediol monoisobutyrate, to decompose and form ceria nanocrystals. The sizes of the nanocrystals are uniform and could be... 

Xue, G., Vaissermann, J., and Gouzerh, P. (2002) Cerium(lll) complexes with lacunary polyoxotungstates. Synthesis and structural characterization of a novel heteropolyoxomngstate based on a-[SbW9033] units. Journal... 

Cerium is the only lanthanide metal with areadily accessible tetravalent oxidation state. Synthesis and molecular structure determination of organometallic Ce(IV) complexes are of interest and a challenge, because the Ce(IV) ion is strongly oxidizing and the anionic ligands typically... 

The synthesis and preliminary X-ray structure of the first organometallic Ce(IV) complex Ce(CsH8)2 was reported in 1976 [115] and reproduced in 1985 [116] by the reaction of cerium(IV) isopropoxide with triethylaluminum in the presence of cyclooctatetraene, as shown in Figure 8.35. The accurate sandwich molecule structure of cerocene has been eon-firmed by an X-ray structural study on the methyl substituted cerocene [Ce(MeCOT)2] [117], Subsequently, two more substituted cerocene analogs have been synthesized via a more efficient method, for example, controlled oxidation of cerium(III) precursors and one of these complexes has been structurally characterized [118],... 

Gulino, A., Casarin, M., Conticellio, V.P. etal. (1988) Efficient synthesis, redox characteristics, and electronic structure of a tetravalent tris(cyclopentadienyl)cerium alkoxide complex. Organometallics, 1, 2360. 

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