An efficient ruthenium(IV) catalyst for the selective hydration of nitriles to amides in water under mild conditions.

A Ru(IV) catalyst able to promote the selective hydration of nitriles to amides in water, at low metal loadings and under mild conditions, is presented.

Asymmetric niobium guanidinates as intermediates in the catalytic guanylation of amines.

The molecular structure of the guanidinate complex {NbBz2(N(t)Bu)[(4-BrC6H4)N=C(N(i)Pr)(NH(i)Pr)]}, previously obtained by reaction of [NbBz3(N(t)Bu)] and the corresponding guanidine proligand, has been established by X-ray diffraction. The series of complexes {NbBz2(N(t)Bu)[(Ar)N=C(N(i)Pr)(NH(i)Pr)]} (Ar = 4-BrC6H4, 4-(t)BuC6H4, 4-MeOC6H4) and {[NbBz2(N(t)Bu)]2[(C6H4)(N=C(N(i)Pr)(NH(i)Pr))2]} show a preferred asymmetric coordination of the guanidinate ligand by means of one alkylamino nitrogen and the arylimino nitrogen atom. Computational studies confirm this preference and the results suggest that electronic factors prevail over steric factors.

Highly efficient redox isomerisation of allylic alcohols catalysed by pyrazole-based ruthenium(IV) complexes in water: mechanisms of bifunctional catalysis in water.

The catalytic activity of ruthenium(IV) ([Ru(η(3):η(3)-C(10)H(16))Cl(2)L]; C(10)H(16) = 2,7-dimethylocta-2,6-diene-1,8-diyl, L = pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, 3-methyl-5-phenylpyrazole, 2-(1H-pyrazol-3-yl)phenol or indazole) and ruthenium(II) complexes ([Ru(η(6)-arene)Cl(2)(3,5-dimethylpyrazole)]; arene = C(6)H(6), p-cymene or C(6)Me(6)) in the redox isomerisation of allylic alcohols into carbonyl compounds in water is reported. The former show much higher catalytic activity than ruthenium(II) complexes. In particular, a variety of allylic alcohols have been quantitatively isomerised by using [Ru(η(3):η(3)-C(10)H(16))Cl(2)(pyrazole)] as a catalyst; the reactions proceeded faster in water than in THF, and in the absence of base.

Access to unusual polycyclic spiro-enones from 2,2'-bis(allyloxy)-1,1'-binaphthyls using Grubbs' catalysts: an unprecedented one-pot RCM/Claisen sequence.

Treatment of 2,2'-bis(allyloxy)-1,1'-binaphthyls with the first-generation Grubbs' carbene under MW-irradiation results in the formation of new polycyclic spiro-enones through an unprecedented RCM/Claisen sequence.

Synthesis and structure of ruthenium(IV) complexes featuring N-heterocyclic ligands with an N-H group as the hydrogen-bond donor: hydrogen interactions in solution and in the solid state.

The synthesis and characterization of novel ruthenium(IV) complexes [Ru(η(3):η(3)-C(10)H(16))Cl(2)L] [L = 3-methylpyrazole (2b), 3,5-dimethylpyrazole (2c), 3-methyl-5-phenylpyrazole (2d), 2-(1H-pyrazol-5-yl)phenol (2e), 6-azauracile (3), and 1H-indazol-3-ol (4)] are reported. Complex 2e is converted to the chelated complex [Ru(η(3):η(3)-C(10)H(16))Cl(κ(2)-N,O-2-(1H-pyrazol-3-yl)phenoxy)] (5) by treatment with an excess of NaOH. All of the ligands feature N-H, O-H, or C═O as the potential hydrogen-bonding group.

Prediction of airborne Alnus pollen concentration by using ARIMA models.

To take preventative measures to protect allergic people from the severity of the pollen season, one of aerobiology's objectives is to develop statistical models enabling the short- and long-term prediction of atmospheric pollen concentrations. During recent years some attempts have been made to apply Time Series analysis, frequently used in biomedical studies and atmospheric contamination to pollen series. The aim of this study is to understand the behaviour of atmospheric alder pollen concentrations in northwest Spain in order to develop predictive models of pollen concentrations by using Time Series analysis.