Chirality in Distorted Square Planar Pd(O,N)2 Compounds |
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| Authors: | Henri Brunner Michael Bodensteiner Takashi Tsuno |
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| Institution: | 1. Institut für Anorganische Chemie, Universit?t Regensburg, , Regensburg, Germany;2. Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, , Japan |
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| Abstract: | Salicylidenimine palladium(II) complexes trans‐Pd(O,N)2 adopt step and bowl arrangements. A stereochemical analysis subdivides 52 compounds into 41 step and 11 bowl types. Step complexes with chiral N‐substituents and all the bowl complexes induce chiral distortions in the square planar system, resulting in Δ/Λ configuration of the Pd(O,N)2 unit. In complexes 1 , 2 , 3 , 4 , 5 , 6 with enantiomerically pure N‐substituents ligand chirality entails a specific square chirality and only one diastereomer assembles in the lattice. Dimeric Pd(O,N)2 complexes with bridging N‐substituents in trans‐arrangement are inherently chiral. For dimers 7 , 8 , 9 , 10 , 11 different chirality patterns for the Pd(O,N)2 square are observed. The crystals contain racemates of enantiomers. In complex 12 two independent molecules form a tight pair. The (RC) configuration of the ligand induces the same Δ chirality in the Pd(O,N)2 units of both molecules with varying square chirality due to the different crystallographic location of the independent molecules. In complexes 13 and 14 atrop isomerism induces specific configurations in the Pd(O,N)2 bowl systems. The square chirality is largest for complex 15 (Diop)Rh(PPh3)Cl)], a catalyst for enantioselective hydrogenation. In the lattice of 15 two diastereomers with the same (RC,RC) configuration in the ligand Diop but opposite Δ and Λ square configurations co‐crystallize, a rare phenomenon in stereochemistry. Chirality 25:663–667, 2013. © 2013 Wiley Periodicals, Inc. |
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| Keywords: | square chirality Δ /Λ configuration salicylidenimine palladium(II) complexes Pd(O N)2 compounds |
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