Octahedral to trigonal prismatic distortion driven by subjacent orbital π antibonding interactions and modulated by ligand redox noninnocence.

Ru(ONO)2 and Os(ONO)2 distort from octahedral towards trigonal prismatic geometry in order to relieve π antibonding due to donation from the second-highest ligand orbital to the metal. Increasing oxidation of the ONO ligand suppresses distortion by increasing σ* interactions in the trigonal prism.