The crystal structure of bis[(E)-4-bromo-2-({[2-(pyridin-2-yl)ethyl]imino}methyl)phenol]nickel(II) bis[(E)-4-bromo-2-({[2-(pyridin-2-yl)ethyl]imino}methyl)phenolato]nickel(II) bis(perchlorate) methanol monosolvate, a structure containing strong inter-species hydrogen bonds

The title compound, [Ni(C14H12BrN2O)2][Ni(C14H13BrN2O)2](ClO4)2·CH3OH consists of two mononuclear ([Ni(HL)2]2+ and [NiL2]) complex molecules linked by strong hydrogen bonding [O...O separations of only 2.430 (5) Å], which is the shortest reported to date for such species. In one of the complexes, both the coordinated phenoxy groups retain their protons and thus this is the cationic equivalent species of the other complex where both coordinated phenoxy groups are deprotonated. In addition, perchlorate anions are present for charge balance, as well as methanol solvate molecules. For the neutral NiL2 complex, each 2-ethylaminepyridine arm is disordered over two equivalent conformations with occupancies of 0.750 (8):0.250 (8). The perchlorate anion is disordered over two equivalent conformations with occupancies of 0.602 (8):0.398 (8). The perchlorate ions also link to the H atoms on the methanol methyl and hydroxyl groups. These interactions link the moieties into a complex three-dimensional array. The crystal studied was refined as a two-component twin