Involved in the archaeal biosynthesis of heme. Catalyzes the oxiation of precorrin-2 into sirohydroclorin (By similarity). NAD(+) + precorrin-2 = 2 H(+) + NADH + sirohydrochlorin Porphyrin-containing compound metabolism; siroheme biosynthesis; sirohydrochlorin from precorrin-2: step 1/1. Homodimer. Belongs to the precorrin-2 dehydrogenase / sirohydrochlorin ferrochelatase family.