Abstract: Naphthacene-5,12-diones which are substituted by at least one organic thio radical are not only photoinitiators for the photopolymerization but also sensitizers for the photodimerization of ethylenically unsaturated compounds. Compositions made of these naphthacene-5,12-diones and ethylenically unsaturated compounds are suitable for the preparation of printing inks, paints, printing plates, resist materials or as image recording material.

Abstract: Coated material containing in successive order(a) a substrate,(b) a photostructurable negative-working thermostable adhesive and(c) a self-supporting photocrosslinkable polyimide film.This arrangement can be used for producing relief images by means of photolithhographic processes.

Abstract: Optically active iridium complexes of the formula ##STR1## in which R is methyl and R.sup.1 is a hydrocarbon radical having at least one chiral C atom or a hydrocarbon radical containing at least one hetero atom and having at least one chiral C atom; or R is a hydrogen atom and R.sup.1 is 1,2-diphenylethyl or a 5-membered or 6-membered cycloaliphatic or cycloheteroaliphatic radical having at least two chiral C atoms and a phenyl group or alkyl group in the .alpha.-position, X.sup..crclbar. is an anion of a monobasic inorganic or organic acid and Y and Z are each ethylene, or Y and Z together represent an open-chain or cyclic diene which has 6 to 10 C atoms and whose diene groups are bonded via 1 or 2 C atoms.They are suitable as enantioselective, homogeneous catalysts for the transfer hydrogenation of, in particular, prochiral ketones with secondary alcohols.