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The commensurate crystal structure of the magnetic phase occurring below 7 K of the multiferroic Pb2MnWO6 perovskite has been solved by the introduction of the superspace approach. This lead based double perovskite is characterized by a complex ferrielectric non-centrosymmetric nuclear structure with orthorhombic symmetry stable in a wide temperature range. As indicated from the analysis of powder neutron diffraction data, the low temperature antiferromagnetic structure showing a propagation vector k 1/4 [1/4 0 0] is stabilized by a multi-step process involving the evolution from incommensurate to commensurate spin ordering with a concomitant change of the magnetic symmetry. The determination of the Pb2MnWO6 magnetic structure offers a meaningful example of the superspace application and provides a detailed phase diagram of the involved magnetic states. Nowadays this ordered perovskite could be considered as a new type of multiferroic material combining ferrielectric properties and a long period antiferromagnetic structure.

2-Phenyl-1H-indole reacts with p-anisidine, 2-nitro-p-anisidine and 2-nitro-p-methylaniline, under anodic oxidation, to give several products, depending on the potential used and on the presence or the absence of oxygen and a deprotonating agent. This investigation gives new insights into the reactivity of radical cations generated by a controlled anodic potential and neutral radicals corresponding to either 2-phenyl-1H-indole or to the three amines studied. The chosen amines show oxidation potentials lower (p-anisidine), equal (2-nitro-p-anisidine) or higher (2-nitro-p-methylaniline) than that of 2-phenyl-1H-indole and the reactions were carried out at the potential of the studied compounds. The oxidation of 2-phenyl-1H-indole in oxygen affords a new indole derivative, whose formation has been explained by β-scission of an indol-2-yloxyl radical and its structure was confirmed by X-ray analysis.

3-Indolinonic (1a) and 3-phenyliminoindolinonic (1b) 1-oxides react at carbon 2 with diethyl malonate and ethyl acetoacetate anions, yielding intermediate anions which undergo cyclization in the reaction medium to form an isoxazolidine ring. The cyclization occurs through the interaction of the oxygen of the primitive N-oxide function with a carbonyl group of the reagents. The same substrates react with dilithium phenylacetate anion, leading to the formation of stable and water-soluble carboxylated aminoxyls. The indolenin-3-one 2a and its corresponding 3-phenylimino derivative 2b also react with the above-mentioned nucleophiles to form carboxylated 3-indoxyls without cyclization; oxidation with m-chloroperbenzoic acid does not yield carboxylated aminoxyls in appreciable amount. The structure of the product of cycloaddition obtained from the reaction of compound 1a with diethyl malonate was determined by X-ray analysis.

N,N-Dimethyl-p-nitrosoaniline reacts with benzoyl chloride affording a complex salt containing a cation, a hybrid between a nitrenium ion and an iminium ion. The salt reacts with nucleophiles (indoles, indolizines) yielding compounds characterized by a new carbon–nitrogen bond, derived from the nitrenium ion form. According to the type of nucleophile, the reaction, to differing extents, is in competition with an electron transfer process which leads to the formation of the dimer of the nucleophile and of the azoxy corresponding to the N,N-dimethyl-p-nitrosoaniline. In one of the reactions studied, a chlorinated azoxy derivative was also isolated, and its structure was elucidated by X-ray analysis.

Crystal structures of benzthiazide [6-chloro-3-[[(phenylmethyl)thio]ethyl]4H-1,2,4-benzthiadiazine-7-sulfonamide-1,1,dioxide] in its anhydrate and monohydrate forms reveal, respectively, a J-like folded as well as extended type conformations that have critical torsional flexibility along the C–C–S–C bonds and novel H-bonded sulfonamide motifs.