Azaporphyrin derivatives of the formula ##STR1## where R.sup.1 and R.sup.2 are each, independently of one another, hydrogen, unsubstituted or substituted C.sub.1 -C.sub.20 -alkyl, C.sub.5 -C.sub.7 -cycloalkyl or unsubstituted or substituted phenyl, or two adjacent R.sup.1 radicals form, together with the carbon atoms to which they are bonded, an unsaturated or aromatic 5- to 7-membered carbocyclic ring,X are each hydrogen or C.sub.1 -C.sub.4 -alkyl andp are each 1 or 2, andbiladienes of the formula ##STR2## where R.sup.1, R.sup.2, X and p each have the abovementioned meanings, m and n are each 0 or 1 and An.sup..crclbar. is an anion, as intermediates therefor, are used for preparing vinylogous porphyrin derivatives.