Highly Crowded trans-Olefin. Molecular Structure of trans -1, 2-Bis{meso-[nickel(II)octaethylporphyrinyl]}ethene
X-Ray analysis of trans-1,2-bis{meso-[nickel(II)octaethylporphyrinyl]} ethene has revealed that the compound has nonplanar structure and the nickel-coordination planes of porphyrin rings are close to perpendicular (72.5°) to the plane of the central double bond. Both porphyrin rings have saddle-shaped structure due to the steric repulsion between ethyl substituents.