Two tetranuclear manganese(II) complexes (2) and (3) have been obtained by Schiff-base condensation of 1,3-diamino-2-hydroxypropane and 2,6-diacetylpyridine in the presence of Ba²⁺, followed by transmetallation using Mn²⁺. The complexes have been characterised by analytical, spectroscopic, ²⁵²Cf plasma desorption mass spectroscopic, and single-crystal X-ray diffraction methods. Complex (2) contains a 40-membered macrocycle formed by a (4 + 4) Schiff-base condensation of four molecules of 1,3-diamino-2-hydroxypropane with four molecules of 2,6-diacetylpyridine. The macrocycle is wrapped around a cubane-like Mn₄(alkoxide)₄ core. Complex (3) is dimeric. The asymmetric unit contains two binuclear, 20-membered macrocycles each formed by a (2 + 2) Schiff-base condensation reaction. This complex contains five geometrically distinct thiocyanate groups. Routes for the formation of (3) are discussed and the possible significance of the compounds as models for the photosynthetic water-splitting system is noted.