[1-(TRIMETHYLSILYL)ALLYL]LITHIUM - STRUCTURE IN SOLUTION AND ROTATIONAL BARRIERS

NMR data show that the title compound, 10, exists in a variety of media exclusively in the exo form. NOE experiments, 6Li{1H}, indicate that 6Li is near the C1 and C3 of the allyl moiety and far from C2. The complex of 10 with N,N,N',N̋,-N̋-pentamethyldiethylenetriamine (PMDTA) is concluded to exist as two monomeric tridentately coordinated contact ion pairs with lithium near C1 or C3. Rotation of coordinated Li+ in these complexes with respect to the allyl loop is slow at 150 K and ΔH* is 7.7 kcal. Barriers to rotation about the CHCH2 bond depend critically on solvent varying between 11 and 17 kcal. © 1993, IEEE. All rights reserved. © 1990, American Chemical Society. All rights reserved.