Toward solution-state structure.: A 6Li,1H HOESY NMR, X-ray diffraction, semiempirical (PM3, MNDO), and ab initio computational study of a chiral lithium amide

Computational studies of a chiral lithium amide (lithium (2-methoxy-(R)-1-phenylethyl)((S)-1-phenylethyl)amide, 3) using the solid-state structure as a reference geometry showed that there were only small differences between the X-ray and ab initio and PM3 calculated structures. Furthermore, we have shown that reference distances from either X-ray or ab initio/PM3 can be used for the calculation of Li-H distances using Li-H NOE data. The calculations of Li-H distances using HOESY buildup rates showed that the solution structure of 3 THF is similar to the structure obtained in the gas phase (calculated) and in the solid phase (X-ray). Small variations of +/-0.2 Angstrom were observed between X-ray/ab initio and NOE data for distances less than 4 Angstrom.