Ce(IV) complexes with donor-functionalized alkoxide ligands: improved precursors for chemical vapor deposition of CeO2

Thin films of ceria (CeO(2)) have many applications, and their synthesis by liquid-injection MOCVD (metal-organic chemical vapor deposition) or ALD (atomic layer deposition) requires volatile precursor compounds. Here we report the synthesis of a series of homoleptic and heteroleptic Ce(IV) complexes with donor-functionalized alkoxide ligands mmp (1-methoxy-2-methylpropan-2-olate), dmap (1-(dimethylamino)propan-2-olate), and dmop (2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)propan-2-olate) and their potential as precursors for MOCVD and ALD of CeO(2). New complexes were synthesized by alcohol exchange reactions with [Ce(OBu(t))(4)]. [Ce(mmp)(4)] and [Ce(dmap)(4)] were both found to be excellent precursors for liquid-injection MOCVD of CeO(2), depositing high purity thin films with very low carbon contamination, and both have a large temperature window for diffusion controlled growth (350-600 °C for [Ce(mmp)(4)]; 300-600 °C for [Ce(dmap)(4)]). [Ce(mmp)(4)] is also an excellent precursor for liquid-injection ALD of CeO(2) using H(2)O as oxygen source and demonstrates self-limiting growth from 150 to 350 °C. [Ce(dmap)(4)] has lower thermal stability than [Ce(mmp)(4)] and does not show self-limiting growth in ALD. Heteroleptic complexes show a tendency to undergo ligand redistribution reactions to form mixtures in solution and are unsuitable as precursors for liquid-injection CVD.     

Facile syntheses of 7,9-dimethoxypyrrolo[3,2,1-ij]quinolin-6-ones

The activated dimethoxypyrrolo[3,2,1-ij]quinolin-6-one ring system was synthesized via two approaches, starting from an indole and quinolin-4-one, respectively. Subsequent demethylation led to both monohydroxy- and dihydroxypyrrolo[3,2,1-ij]quinolin-6-ones.     

Synthesis of symmetrical and unsymmetrical diindolylmethanes via acid-catalysed electrophilic substitution reactions

A range of activated indole-2-carboxylate derivatives was prepared via the Hemetsberger indole synthesis. Vilsmeier formylation was explored to establish regioselectivity and to prepare a range of new indole carbaldehydes. The indole aldehydes were reduced to the corresponding hydroxymethylindoles in good yields by the use of sodium borohydride in THF. Symmetrical 4,4′-, 6,6′- and 7,7′-diindolylmethanes were prepared via the acid-catalysed reaction of the corresponding hydroxymethylindoles. Furthermore, the treatment of methyl 4-hydroxymethyl-5,6-dimethoxyindole-2-carboxylate and a range of methyl indole esters with acetic acid led to the formation of unsymmetrical 4,6′- and 4,7′-dindolylmethanes.     

Extending the Family of V4+ S=${{ 1/2 }}$ Kagome Antiferromagnets

The ionothermal synthesis, structure, and magnetic susceptibility of a novel inorganic–organic hybrid material, imidazolium vanadium(III,IV) oxyfluoride [C₃H₅N₂][V₉O₆F₂₄(H₂O)₂] (ImVOF) are presented. The structure consists of inorganic vanadium oxyfluoride slabs with kagome layers of V⁴⁺ S=${{ 1/2 }}$ ions separated by a mixed valence layer. These inorganic slabs are intercalated with imidazolium cations. Quinuclidinium (Q) and pyrazinium (Pyz) cations can also be incorporated into the hybrid structure type to give QVOF and PyzVOF analogues, respectively. The highly frustrated topology of the inorganic slabs, along with the quantum nature of the magnetism associated with V⁴⁺, means that these materials are excellent candidates to host exotic magnetic ground states, such as the highly sought quantum spin liquid. Magnetic susceptibility measurements of all samples suggest an absence of conventional long‐range magnetic order down to 2 K despite considerable antiferromagnetic exchange.     

Thiol-ene UV-curable coatings using vegetable oil macromonomers

Allyl, acrylate, and vinyl ether derivatives of castor oil were synthesized and blended with multifunctional thiols for evaluation as thiol-ene ultraviolet (UV) curable systems. The UV cured films were characterized and evaluated via ASTM tests, gel content, and dynamic mechanical analysis (DMA) as a function of time. Fourier transform infrared spectroscopy and DMA studies established that property advancement resulted from auto-oxidation, continued thiol-ene polymerization, or a combination of both mechanisms.     

Borrowing hydrogen: iridium-catalysed reactions for the formation of C-C bonds from alcohols

Alcohols have been employed as substrates for C-C bond-forming reactions which involve initial activation by the temporary removal of hydrogen to form an aldehyde. The intermediate aldehyde is converted into an alkene via a Horner-Wadsworth-Emmons reaction, nitroaldol and aldol reactions. The 'borrowed hydrogen' is then returned to the alkene to form a C-C bond.