Three tetraphenylborates of mononuclear Mn(III) cation complexes with hexadentate ligands, the products of the reaction between a N,N′‐bis(3‐aminopropyl)ethylenediamine and salicylaldehydes with the different haloid substitutions at the 5 or 3,5 positions, have been synthesized: Mn(5‐F‐sal‐N‐1,5,8,12)BPh4 (1), Mn(3,5‐diCl‐sal‐N‐1,5,8,12)BPh4 (2) and Mn(3,5‐Br,Cl‐sal‐N‐1,5,8,12)BPh4 (3). Their crystal structure, dielectric constant (ϵ) and magnetic properties have been studied. Ligand substituents have a dramatic effect on the structure and magnetic properties of the complexes. With decreasing temperature, the complex (1) shows a gradual spin crossover from the high‐spin state (HS) to the HS:LS intermediate phase, followed by an abrupt transition to the low‐spin state (LS) without changing the crystal symmetry. The complexes 2 and 3 are isostructural, but have fundamentally different properties. Complex 2 demonstrates two structural phase transitions related to sharp spin crossovers from the HS to the HS:LS intermediate phase at 137 K and from the intermediate phase to the LS at 87 K, while complex 3 exhibits only one spin transition from the HS to the HS:LS intermediate phase at 83 K. Effect of halide substituents on spin and phase transitions in Mn(III) complexes