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13 C 13 C coupling constants in derivatives of trans ‐stilbene and tetraphenylethylene. Determination of relative signs II
Author(s) -
Hansen P. E.,
Poulsen O. K.,
Berg A.
Publication year - 1976
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270081209
Subject(s) - coupling constant , tetraphenylethylene , chemistry , sign (mathematics) , context (archaeology) , coupling (piping) , crystallography , physics , materials science , quantum mechanics , mathematics , mathematical analysis , paleontology , fluorescence , metallurgy , aggregation induced emission , biology
Abstract Magnitudes and signs of 13 C 13 C coupling constants in compounds of the type Ph 13 CR 1 R 2 13 CR 1 R 2 Ph have been determined and the results are discussed in a broader context. Two types of coupling constants, J (C‐i, C‐α) and J (C‐i, C‐β), between aromatic carbon atoms and the benzylic carbons, probably with different coupling mechanisms, are considered. Whereas 2 J (C‐2, C‐α) are always found positive, 2 J (C‐1, C‐β) in the present compounds are found to be negative or about zero. 3 J (C‐3, C‐α) has the same sign as 2 J (C‐2, C‐α). A 4 J and a 5 J were observed in trans ‐stilbene.