Ellipsometry was used to study the electrodeposition of polymer films formed by oxidation of bipyrazine, polyvinylferrocene, and aniline. For polymeric films of limited thickness displaying good optical characteristics (i.e., high reflectivity, uniform coverage, and homogeneity), the film refractive index and thickness were determined. Nonideal ellipsometric behavior was observed when film morphology varied with film growth. Po]yvinylferrocene films in 0.1M TBABFJacetonitrile were shown to be 15% thicker in the oxidized form than in the reduced form.

Rapid-injection is a very useful technique for the preparation of temperature-sensitive and air-sensitive compounds in the cold, nitrogen-filled probe of an NMR spectrometer. We have used this method to prepare solutions of pi-complexes from 2-cyclohexenone and prototypical cuprates Me2CuLi.LiI and Me2CuLi.LiCN, and we have assigned structures on the basis of 1H and 13C NMR. In each case two pi-complexes were observed, and in the former, their rates of formation were measured by rapid-injection 1H NMR and EXSY spectroscopy. These results provide insights into the normal and anomalous conjugate addition reactions of organocuprates.

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SYNOPSISModel compounds for imines formed during the thermal curing of short chain polyimides have been synthesized and characterized. These compounds have imine bonds ( C = N ) formed by the nucleophilic attack of primary amines on imide carbonyls. The C = N stretching mode appears at 1649-1664 cm-' in the Raman and infrared spectra of these compounds and the band assigned to the carbonyl mode in an imide ring with an imine bond appears near 1740 cm-' . These compounds have been prepared and characterized to verify the conclusions of a previously reported study in which bands observed in thermally cured short chain polyimides a t 1656 and 1742 cm-' were assigned as the C=N and associated C =O modes, respectively. It has also been confirmed that the C = N stretching mode in the imide model compounds is inherently IR weak and can only be seen if the concentration of imine species is high. 0 1993 John Wiley & Sons, Inc.

PMDA-ODA polyimide thin films can be formed by vapor co-deposition of the precursor molecules PMDA (pyromellitic dianhydride) and ODA (4, 4′-oxydianiline) if the resulting polyamic acid film is heated to a 473 to 573 K cure step. We have used laser Raman spectroscopy to study how dose composition, dose rate, and substrate temperature influence the properties of the resulting polyimide films. We find that only doses with excess PMDA produce high quality films. Doses with 1 : 1 stoichiometry or excess ODA produce thermally unstable films that contain imine bonds; these films decompose below 575 K. Dosing onto substrates below 315 K produces the polyamic acid precursor of polyimide. At higher substrate temperatures, films with high defect densities or decomposed films are produced. The equilibrium vapor pressures of ODA and PMDA are reported.