Enantiopure Phospha[1]ferrocenophanes: Textbook Examples of Through‐Space Nuclear Spin–Spin Coupling

• Published in: Chemistry : a European journal 2018-06, Vol.24 (33), p.8298-8301
• Main Authors: Sadeh, Saeid, Cao, My P. T., Quail, J. Wilson, Zhu, Jianfeng, Müller, Jens
• Format: Article
• Language: English
• Subjects: Chemistry; Chirality; Coupling (molecular); Ferrocenophanes; Magnetic resonance spectroscopy; Metathesis; NMR spectroscopy; Nuclear spin; Phosphorus; planar chirality; sandwich complexes; Spin-spin coupling; strained molecules; through-space coupling
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201801139

Three enantiopure phospha[1]ferrocenophanes (2R) equipped with either a phenyl, an isopropyl, or a tert‐butyl group at the bridging phosphorus atom were synthesized by a salt‐metathesis approach in isolated yields between 52 and 63 %. The chirality in these strained sandwich compounds stems from the planar‐chiral ferrocene moiety, which is symmetrically equipped with two iPr groups adjacent to phosphorus. Surprisingly, all three phospha[1]ferrocenophanes show an uncommon through‐space nuclear 1H–31P coupling. As a result of the embedded symmetry, these new compounds are ideal examples to differentiate between through‐space and through‐bond coupling mechanisms in NMR spectroscopy. Three enantiopure phospha[1]ferrocenophanes were synthesized by a salt‐metathesis approach and revealed an uncommon through‐space nuclear 1H−31P coupling. As a result of the embedded symmetry, these new compounds are ideal examples to differentiate between through‐space (green line) and through‐bond (red line) coupling mechanisms in NMR spectroscopy.