SynopsisSulfur-bridged polyaniline coatings are obtained onto Fe anodes by electrolyzing a basic solution of one aniline and ammonium sulfide. Their sulfur content ranges from 7% to 1770, depending on the substituents on aniline. Variously substituted anilines may be polymerized in this way and coating pollution by azobenzene formed in a side reaction is almost completely avoided. Sulfur probably enters the polymer chains through a free radical mechanism, H S intermediates being formed by both homogeneous and anodic oxidation of HS-anions. Coatings from N-allylaniline, being thermally curable, show satisfactory physical properties.

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The structural investigation of four bio- and synthetic melanins, obtained by the action of polyphenol oxidase from potatoes and Psalliota campestris mushrooms and of tyrosinase from Sepia officinalis on tryptophan, or by means of performic oxidation, has been carried out by thermal decomposition performed in the ion source of a mass spectrometer. The structural characterization of the ionic species [C8H7ON](+.), common and abundant for all the examined compounds, has been obtained by accurate mass measurements and collisional spectroscopy. These mass spectrometric techniques have shown unequivocally for ionic species [C8H7ON](+.) the structure of 2-indolinone.

A series of oxazoline compounds have been prepared by reaction of 2,6‐diformyl‐4‐chlorophenol, 2,6‐diformylpyridine or 2,5‐diformylthiophen with o‐aminophenol or o‐aminothiophenol respectively. The oxazoline derivatives are stable both in solid state and in solution while the thiazoline derivatives easily oxidize to the corresponding thiazoles. Physico‐chemical data confirm this oxidation process. The 70 eV electron impact induced decomposition pathways of these compounds, obtained with the aid of exact mass measurements, B/E linked scans and collisional spectroscopy, are discussed in detail.

The fast atom bombardment (FAB) induced decomposition pattern of the ionic bis(carbene)gold(IIl) complex [((p-MeC6H4NH)(EtO)C}2Au12]C104 (1) is described and discussed in detail with the aid of metastable data. A lack of [MI+ ions is observed when sulfolane is used as the matrix. Instead, the molecular species observed is the [M -HI'+ ion. The fragmentation pattern can be considered as a retrosynthetic process of the compound itself, never previously observed for an organometallic under FAB conditions. The MS pattern suggests the synthesis of the new carbene-methanide derivative 2, [((p-MeC6H4NH)-(EtO)CJ((p-MeC,H,N=)(EtO)C}Au], observed under FAB-MS conditions as the most stable ion. An independent synthesis was successful.