AbstractThe macrocyclic chelator 1,4,7‐triazacyclononane‐1,4,7‐tri(methylenephosphonic acid) (H₆NOTP) has shown significant promise for use in positron emission tomography with the positron‐emitting radionuclide ⁶⁸Ga³⁺. We report the X‐ray crystal structure of the neutral complex 1,4,7‐triazacyclononane‐1,4,7‐tri(methylenephosphonato)gallium(III) ([Ga(H₃NOTP)]), which crystallised in the centrosymmetric space group P2₁/n. The coordination geometry of the Ga³⁺ ion is distorted octahedral with three macrocyclic amine N donor atoms and three singly deprotonated phosphonato O donor atoms. Two discrete enantiomers, Δ(λλλ)‐SSS and Λ(δδδ)‐RRR, are present as a racemate within the unit cell. Intermolecular hydrogen bonds between phosphonic acid groups of adjacent complexes form a two‐dimensional sheet network. Density functional theory (DFT) calculations supported the observation of complexes with low electric field gradient values with slight but significant deviations from ideal octahedral geometry. The DFT calculations were also used to investigate the influence of intermolecular interactions and ligand protonation states on the coordination environment and surface charge distribution.