Structures of Allyl Ligands

CHAPTER 3 COVALENT (x-TYPE) LIGANDS BOUND THROUGH METAL-CARBON AND METAL-HYDROGEN BONDS 

For simple Tf) -allyl groups that are static on the NMR time scale, the H NMR spectrum contains several characteristic feahues. The anti protons, which are closest to the metal and thus shielded, resonate at the highest field of the different aUyl protons, typically between 81 and 8 3. The syn protons appear between 8 2 and 8 5, and the central proton between 8 4. and 8 6.5. The coupling constant between the syn and anti protojas is often too small to measure, but they do couple more strongly with die central proton, with coupling constants of approximately 7 and 11 Hz, respectively. The relative chemicals shifts of the allyl carbons in the NMR spectra mirror those of the protons. The terminal carbons resonate between 8 80 and 8 90, and the central carbon resonates between 8 110 and 8 130. 

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