Redox behavior of cyclo[6]pyrrole in the formation of a uranyl complex

A uranyl complex, the first metal complex to be formed from the cyclo[n]pyrrole series of expanded porphyrins, is formed when cyclo[6]pyrrole is treated with the uranyl cation under aerobic conditions. Spectroscopic, spectroelectrochemical, and electron spin resonance data of this species are consistent with the ligand in the complex being oxidized to an antiaromatic form.     

Trivalent lanthanide lacunary phosphomolybdate complexes: a structural and spectroscopic study across the series [Ln(PMo11O39)2]11-

We report the syntheses and crystal structures of (NH4)11[Ln(III)(PMo11O39)2.xH2O (where Ln = every trivalent lanthanide cation except promethium) in which two lacunary [PMo11O39]7- anions sandwich an 8-coordinate Ln(III) cation to yield the complex anion, [LnIII(PMo11O39)2]11-. The 14 salts crystallise in two different space groups, C2/c or P1, but the LnIII containing anions are isostructural across the whole series, a very rare example of such a complete study. Solid state and solution 31P NMR, Raman and IR spectroscopies have been used to prove the stability of [Ln(PMo11O39)2]11- in aqueous solution. As expected, the LnIII cation contracts across the series and the Ln-O bond distances decrease uniformly. Interestingly, the splitting in the nu(P-O) mode within the [PMo11O39]7- unit increases uniformly across the series, which we attribute to the stronger interaction with the smaller, higher charge density LnIII cation as the series is traversed. For the 31P NMR measurements a direct comparison of Lanthanide Induced (paramagnetic) Shift could be made with the analogous [P(W11O39)2]11- complexes.     

Selective hydrogenolysis of novel benzyl carbamate protecting groups

[formula: see text] Highly efficient and selective hydrogenolysis of the 2-naphthylmethyl carbamate group (CNAP) in the presence of the 4-trifluoromethylbenzyl carbamate group (CTFB) has been observed for a wide range of substrates.     

A novel zirconium polyoxometalate compound: (NH4)9[Zr2(μ‐OH)(H2O)2(AsOH)2(AsW7O28)(AsW10O36)]·26H2O

The crystal structure of the title compound, nona­ammonium (arsenic decatungstido)(arsenic heptatungstido)­di­aqua‐μ‐hydroxo‐(hydroxy­arsenido)­di­zir­conium hexa­cosa­hydrate, which was ob­tained from the reaction of [NaAs₄W₄₀O₁₄₀]²⁷⁻ with Zr^IV, has been determined. The anionic complex consists of two hydroxyl‐bridged seven‐coordinate capped trigonal‐prismatic zirconium ions, which are bonded to an [AsW₁₀O₃₆]⁹⁻ anion and to an [AsW₇O₂₈]¹¹⁻ anion that has two {AsOH}²⁺ capping units. The asymmetric unit contains half of the complex, with one crystallographically independent Zr atom. Crystallographic m symmetry imposed by the monoclinic C2/m space group gives rise to the asymmetric unit comprising half of the complex with one crystallographically independent Zr atom.     

Recent developments in nonaqueous plutonium coordination chemistry

This account highlights recent research from our laboratory on nonaqueous plutonium coordination chemistry. The preparation of organic-soluble synthons, the reactivity of plutonium with soft donor atom ligands, and initial characterization of resultant complexes are presented. Homoleptic soft donor complexes are targeted, to contrast with the much larger body of actinide chemistry that focuses covalency and reactivity within one to three sites in the coordination sphere. Structural parameters from X-ray structure determination and computation indicate small, yet significant, differences in covalency between isostructural plutonium and lanthanide complexes. Results are discussed in the context of our aim to expand the fundamental chemistry of plutonium, particularly to address challenges in the nuclear industry.     

Double conjugate addition of dithiols to propargylic carbonyl systems to generate protected 1,3-dicarbonyl compounds

The work describes the efficient double conjugate addition of ethane and propane dithiols in the presence of sodium methoxide to a wide variety of propargylic carbonyl containing compounds. The products of these reactions are differentiated, 1,3-dicarbonyl systems useful for various synthesis programs. By judicious use of hydroxylated substrates tandem cyclization occurs to afford tetrahydropyran lactols or, in the case of hydroxy-substituted propargylic esters, lactones. The corresponding amino-substituted propargylic aldehydes gives piperidine derivatives upon double conjugate addition tandem cyclization.