The reaction of fumaric acid with Mn(CH3COO)2P4H2O gives the polymeric complex {Mn(fum)}n (1). Complex 1 reacts with 2,29-bipyridine in ethanol to yield [Mn(fum)(bipy)(H2O)]n (2). Reaction of 1 with 2 equiv. of 1,10-phenanthroline produces [Mn2(fum)2(phen)2.5]P3H2O (3) and [Mn(phen)2(H2O)2](fum)P4H2O (4). The molecular structures of 2 and 4 were determined by Xray crystallography. In 2 the fumarate anions link the manganese ions so that each is seven coordinate, being bonded to a bidentate bipyridine, two bidentate carboxylates and one H2O molecule. In 4 the asymmetric unit contains a [Mn(phen)2(H2O)2]2q cation, half of each of two independent fumarate anions and four lattice H2O molecules. The cations and anions are interconnected by water molecules hydrogen bonded to both coordinated water molecules and fumarate oxygens. The fumarate complexes, the metal free ligands and a number of simple manganese salts were each tested for their ability to inhibit the growth of Candida albicans. Only the ‘metal free’ 1,10-phenanthroline and its fumarate complexes exhibit fungitoxic activity.