Almost identical geometrical parameters are obtained in both cases). In contrast to 2b, a set of (Ra) and (Sa) atropisomers of 3b were identified in the asymmetric unit of the single crystal. A front view and side view of the molecular structure of (Ra)-3b is shown in Figures and, respectively. It should be also noted that one side of the space surrounding the imidazolinylidene ring is largely covered by one of the Cp* ligands. The carbene carbon and N-phosphinoyl oxygen atoms in these atropisomers adopt the anti-orientation with respect to the N-P bond. However, they exhibit different C1-N1-P-O1 torsion angles, i.e. (Ra)-3b: +153.2(7)° and (Sa)-3b: -153.2(7)°, while a C1-N1-P-O1 torsion angle of about 180° is observed in the free SPoxIm. The bond lengths between the Sm and the N-phosphinoyl oxygen atoms in 2b (2.404(7) Å) and 3b (2.442(5) Å) are almost identical. Thus, the bulky SmCp*2 moiety should inhibit the rotation of the N-phosphinoyl moiety upon complexation and induce obvious axial chirality around the N-P bond, even though a flexible imidazolinylidene ring is involved. The P atom is located exactly on the N1-C1-N2 plane in the case of 3b (d ≈ 0 Å) (Figure ). These results demonstrate the key role that the shape of the Lewis acid plays, in addition to its oxophilicity and size, in the effective induction of axial chirality around the N-P bond in PoxIm and SPoxIm. (anti--O-SPoxIm)SmCp*2 3b were obtained from the reaction using SmCp*2(THF)2. In all cases, the carbene carbon atoms remain intact. The N-P axial chirality was clearly induced by the restricted rotation around the N-P bonds via the formation of N-phosphinoyl oxygen-Sm(II) bonds in 2a, 3a, and 3b. These studies successfully reveal new aspects regarding lanthanide complexes of multifunctional and multipurpose carbenes, thus contributing to the expansion of the chemistry of N-heterocyclic carbenes.