A synthetic route to potentially biocidal silsesquioxanes functionalized by quaternary pyridinium functionalities has been developed. N-Alkylation reactions of the precursor compounds 4-(2-(trimethoxysilyl)ethyl)-pyridine (5) and 4-(2-trichloro-silylethyl)pyridine (6) with iodomethane, n-hexylbromide, and n-hexadecylbromide cleanly afforded the corresponding N-alkylpyridinium salts (7–10). The synthesis of a 4-(2-ethyl)pyridine POSS derivative (2) was achieved by capping of the silsesquioxane trisilanol Cy7Si7O9(OH)3 (1) via two different preparative routes. Attempts to use compound 2 as precursor for quaternary pyridinium salt-functionalized POSS derivatives were met with only partial success. Only the reaction with iodomethane cleanly afforded the new N-methylpyridinium salt 12 in high yield, whereas n-hexylbromide and n-hexadecylbromide failed to react with 2 even under forcing conditions.

The recently reported cerium(IV) tripodal Schiff-base complex (TRENDSAL)CeCl (TRENDSAL =[N{CH2CH2N=CH(C(6)H(2)tBu(2)-3,5-O-2}(3)](3-)) serves as excellent starting material for novel Ce4+ coordination compounds. The first cerium(IV) azide, (TRENDSAL)CeN3 and the first cationic cerium(IV) complex, [(TRENDSAL)Ce][BPh4] are both readily accessible from (TRENDSAL)CeCl via simple salt metathesis reaction.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Readily accessible and easy-to-use phenyliodine(III) dichloride, PhICl(2), has been established as an innovative and superior reagent for the one-electron oxidation of cerium(III) complexes, comprising amide, amidinate, and cyclopentadienyl derivatives. Its use allowed the successful synthesis and structural characterization of the first members of three new classes of chloro-functionalized (organo)cerium(IV) compounds, including the long sought-after Cp(3)CeCl.

Synthetic routes leading to two series of (eta(8)-cyclooctatetraenyl)lanthanide(III) scorpionate "mixed sandwich" complexes are reported. The early lanthanide derivatives (COT)Ln(Tp) (Ln = Ce (1), Pr (2), Nd (3), Sm (4)) and (COT)Ln(Tp(Me2)) (Ln = Ce (5), Pr (6), Nd (7), Sm (8)) (COT = eta(8)-cyclooctatetraenyl, Tp = hydrotris(pyrazolyl)borate, Tp(Me2) = hydrotris(3,5-dimethylpyrazolyl)borate) were obtained by reacting the dimeric halide precursors [(COT)Ln(mu-Cl)(THF)]2 with K[Tp] or K[Tp(Me2)], respectively For the late lanthanide elements a different synthetic route was developed. The complexes (COT)Ln(Tp) (Ln = Er (9), Lu (10)) were made by the reaction of (Tp)LnCl2(THF)1.5 with equivalent amounts of K2C8H8. All new compounds were isolated as intensely colored crystalline materials and fully characterized by elemental analyses and spectroscopic methods. The molecular structures of 4, 5, and 8 were elucidated by X-ray diffraction. The optical spectra of compounds 2 and 4-8 were run at room and low temperatures. From the spectra obtained, the underlying crystal field splitting patterns of complexes 2, 4, 6, and 7 were derived and simulated by fitting the free parameters of a phenomenological Hamiltonian. The parameters used allow the estimation of the crystal field strengths experienced by the Ln3+ central ions and the insertion of complexes 2, 4, 6, and 7 into empiric nephelauxetic and relativistic nephelauxetic series. Besides, the experimentally oriented non-relativistic and relativistic molecular orbital schemes of compound 6 were set up and compared with the results of previous model calculations on [Ln(COT)2]-, Pa(COT)2, and U(COT)2.

The title compound, C(9)H(16)O(2), crystallizes with two mol-ecules in the asymmetric unit. The structure displays inter-molecular O-H⋯O hydrogen bonding.

The synthesis of [Ce(Salen')(2)] (1) (H(2)Salen' = NN'-bis(3,5-di-tert-butylsalicylidene)ethylenediamine) was performed using two different approaches. CeCl3 reacts with two equivalents of K(2)Salen' in THF under the formation of [(THF)(2)KCe(Salen')(2)] (2). Complex 2 could be converted to the Ce-IV complex 1 via oxidation with p-benzoquinone and air, respectively. The reversible reduction process was realized using elemental potassium in boiling THE Furthermore, the reaction of the Celv starting material [((BuO)-Bu-t)(4)Ce(THF)(2)] with the "free" ligand H(2)Salen' in boiling toluene lead in the formation of 1 as well.

The Cerium(IV) complexes [{N[CH2CH2N=CH(2-O-3,5-'Bu2C6H2)(3)}CeCl] (1) and [{N[CH2CH2N=CH(2-O-3,5'Bu2C6H2)](3)}Ce(NO3)] (2) were derived from the condensation of tris(2-aminoethyl)amine and 3,5-di-tert-butylsalicylaldehyde and the appropriate Ce starting material CeCl3(H2O)(6) and (NH4)(2)[Ce(NO3)(6)], respectively. Single crystal X-ray diffraction studies reveal monomeric complexes.

The cerium oxidation state in novel calixarene-supported cerium(IV) β-diketonate complexes [p-tBu-calix[4](OMe)2(O)2]Ce(acac)2 (1) and [p-tBu-calix[4](OMe)2(O)2]Ce(hfac)2 (2), which are a new class of potential precursors for homogeneous oxidative transformations, has been determined using X-ray photoelectron spectroscopy (XPS). Cerium oxidation states between 3.6 and 3.65 were detected, distinctly different from their nominal value of +4. An X-ray induced photoreduction of these compounds was detected. Because of the observed stability of the X-ray modified oxidation state under ambient conditions this effect might be used for a long-standing fine tuning of the Ce oxidation state in cerium calixarenes.

The equimolar reaction of Ce(hfac)4 (1) (hfac = 1,1,1,5,5,5-hexafluoropentanedionato) with p-tBu-calix[4](OMe)2(OH)2 in toluene gave the new cerium(IV) calix[4]arene complex {p-tBu-calix[4](OMe)2(O)2}Ce(hfac)2 (2). The single-crystal X-ray structure shows the cone geometry of the calixarene ligand with the methoxy groups coordinated to the cerium; it shows slightly longer cerium–oxygen (acetylacetonate ligand) bond lengths than the corresponding bonds in the analogous nonfluorinated complex {p-tBu-calix[4](OMe)2(O)2}Ce(acac)2 (3). The bromination reaction of 3 gave the bisbrominated complex {p-tBu-calix[4](OMe)2(O)2}Ce(Br-acac)2 (4). 1H NMR spectroscopic studies and a single-crystal X-ray structure of 4 revealed that the bromination took place in the 3-position of the acac ligand. Furthermore, the first X-ray photoelectron spectroscopy (XPS) evaluation of the Ce oxidation state in cerium calix[4]arene complexes 2 and 3 is presented, and X-ray induced changes of Ceox in these complexes are detected. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Ligands containing π-systems are common throughout main group and transition metal chemistry; but have also found significant use in the organometallic chemistry of the f-block elements. Due to the high degree of coordinative saturation, the cyclopentadienyl and phospholyl ligand sets are ideal for the stabilization of compounds containing f-block elements. Cyclopentadienyl and its substituted derivatives have contributed greatly to the overall development of the discipline, with the steric and electronic modularity of the ligand offering great insight into both structure and reactivity.

The reaction of base-free Ph2Be with 1,3-di-isopropyl-4,5- dimethylimidazol-2-ylidene (i-Pr-carbene) in toluene gave the carbene adduct Ph2Be(i-Pr-carbene) (1) as colorless crystal blocks. For comparison, the di-n-butyl ether adduct Ph-2-Be(n-Bu2O) (2) was prepared from BeCl2 and PhLi in a mixture of Et2O and n-Bu2O. Single-crystal X-ray determinations reveal monomeric solid-state structures for both complexes.

This article give a comprehensive overview of the chemistry of organolanthanide and organoactinide complexes published in the year 2005. Besides synthetic and structural aspects of all new compounds, the review also covers applications of organolanthanide and -actinide complexes in homogeneous catalysis, organic synthesis, and materials science.

Ligands containing π-systems are common throughout main group and transition metal chemistry; but have also found significant use in the organometallic chemistry of the f-block elements. Due to the high degree of coordinative saturation, the cyclopentadienyl and phospholyl ligand sets are ideal for the stabilization of compounds containing f-block elements. Cyclopentadienyl and its substituted derivatives have contributed greatly to the overall development of the discipline, with the steric and electronic modularity of the ligand offering great insight into both structure and reactivity.

Ce(acac)(4) (acac = acetylacetonate) reacts with p-'Bu-calix[4](OMe)(2)(OH)(2) (1) in toluene to give the new cerium(IV) calix[4]arene complex [p-'Bu-calix[4](OMe)(2)(O)(2)Ce(acaC)(2)] (2). The compound has been fully characterized by elemental analysis, spectroscopic methods and X-ray single crystal structure analysis.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Reduction of the uranium metallocene [η5-1,2,4-(Me3C)3C5H2]2UCl2 (1), Cp‘2UCl2, in the presence of 2,2‘-bipyridyl and sodium naphthalene gives the dark green metallocene complex Cp‘2U(bipy) (6), which reacts with p-tolyl azide or pyridine-N-oxide to give Cp‘2UN(p-tolyl) (7) or Cp‘2U(O)(py) (8), respectively. The Lewis acid BPh3 precipitates Ph3B(py) and gives the base-free oxo Cp‘2UO (10), which crystallizes from pentane. The oxometallocene 10 behaves as a nucleophile with Me3SiX reagents, but it does not exhibit cycloaddition behavior with acetylenes, suggesting that the polar resonance structure Cp‘2U+−O- dominates the double-bond resonance structure Cp‘2UO.

Treatment of [p-'Bu-calix[4](OMe)(2)(OLi)(2)] with two equivalents of BeCl2 gave the unprecedented dinuclear beryllium complex [p-'Bu-calix[4](OMe)(2)(OBeCl)(2)], which was structurally characterized, both in solution (NMR) and in the solid state (X-ray structure analysis).

Cyclooctatetraene, C8H8, has been made readily available from 1,5-cyclooctadiene in 65% yield without the need of using hazardous or toxic reagents by the straightforward oxidation of the intermediate [Li(tmeda)](2)C8H8 (3, tmeda=N,N,N-1,N-1-tetramethylethylenediamine) with di-tert-butylperoxide. (C) 2004 Elsevier Ltd. All rights reserved.