Exceptional kinetic propensity of hydroxymethyl phosphanes toward Rh(III) stabilization in water

The reactions of (HOCH2)2P(C6H4)P(CH2OH)2 (HMPB) and P(CH2OH)3 (THP) with RhCl3.xH2O in aqueous media gave water-soluble complexes cis-[RhCl2{eta2-(HOCH2)2P(C6H4)P(CH2OH)2}2]Cl (3) and fac-[RhCl3(P(CH2OH)3)3] (4) respectively in good yields, X-ray crystal structures of 3 and 4 confirmed their molecular constitution. These reactions provide the first examples demonstrating the kinetic propensity of hydroxymethyl phosphanes to stabilize Rh in +3 oxidation state in water.     

Formal [1,3] rearrangement of 2-furylmethyl and 2-thienylmethyl vinyl ethers

Benzyl and naphthylmethyl vinyl ethers are inert in LPDE medium, whereas hetcroaromntic methyl vinyl ethers, viz., 2-furyl and 2-thicnylmelhyl vinyl ethers undergo formal [1,3] rearrangement in LPDE medium.     

On the Wigner-Witmer correlation rules for a homonuclear diatomic molecule with the like atoms in identical atomic states

The problem of building the manifold of electronic states of a homonuclear diatomic molecule formed from two like atoms in identical atomic states is readdressed. A conceptually simple approach is presented by invoking a model and all the standard results originally obtained by Wigner and Witmer are reproduced.     

Oxidative cyclization and fragmentation of steroidal alcohols induced by ceric ammonium nitrate

Oxidative cyclizations of steroidal alcohols (1a–1d) using ceric ammonium nitrate (CAN) in aqueous acetonitrile or aqueous acetic acid gave the corresponding cyclic ethers (2a–2d), whereas the tertiary alcohol (4) gave secosteroid (5).     

Chlorination of substituted phenols with chloramine T. A kinetic study

Kinetics of chlorination of substituted phenols with a particular emphasis on p-nitrophenol (PNP) have been extensively studied using chloramine T (CAT). The effect of added mineral acids, neutral salts, and chloride have been investigated in detail. In aqueous acetic acid at high acidities the reactive phenols follow a zero-order process, while PNP or the disubstituted derivatives give a fractional-order dependence on substrate concentration. The concentration dependence of rate with respect to PNP, the chlorinating agent, and acid reveals the rate law 1/k_obs versus 1/[PNP] gave a straight line with a finite intercept. In aqueous dimethylformamide (DMF) and dimethylsulfoxide (DMSO) the reaction shows a second-order dependence on CAT and a first-order dependence on PNP in the case of DMF and a slight increment in order in DMSO. Addition of water increases the rate both in aqueous acetic acid and in dipolar aprotic solvents such as DMF and DMSO. The order of the reaction with respect to CAT is found to be dependent on pH as well as the reactivity of the phenols. In buffered acetic acid medium a second-order dependence on CAT was followed up to pH 7. The rate variations with temperature in the range of 30°¨Dot;50°C have been studied for all the substituted phenols, and the respective activation parameters have been calculated. The empirical rate law is accounted for by a mechanism involving species generated from CAT complexing PNP. Protonated CAT, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm H}_{\rm 2} \mathop {\rm O}\limits^{\rm + } {\rm Cl} $\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Cl}\mathop {\rm O}\limits^{\rm + } {\rm AcH} $\end{document}, and dichloramine T (DCT) are considered important depending on reaction media. The effect of salts, pH, structural variations, and solvent dependence have been accounted for by the proposed mechanism. An attack by positive chlorine on oxygen of the phenol is the preferred mode of attack.     

Intrinsic ferromagnetism in insulating cobalt doped anatase TiO2

Using complementary experiments we show that the room temperature ferromagnetism observed in anatase Co:TiO(2) films is not carrier mediated, but coexists with the dielectric state. TEM and x-ray absorption spectroscopy reveal a solid solution of Co in anatase, where Co is not metallic but in the +2 state substituting for Ti. Measurements at 300 K yield a M(S) of 1.1 mu(B)/Co atom, while all films are highly insulating. The evidence of intrinsic ferromagnetism in the dielectric ground state of Co:TiO(2) leads to new considerations for the origin of ferromagnetism in transition metal doped oxides.