Abstract
Alkane elimination reactions of β-enaminoketonate ligands OCMeCHCMeN(2,6-Me2C6H3) (1), OCMeCHCMeN(2,6,-
i
Pr2C6H3) (2), OCMeCHCMeN(4-
t
Bu-C6H3) (3) with ZnEt2 afforded bis-chelate and bimetallic zinc com-plexes [(OCMeCHCMeNAr)2Zn]; Ar = 2,6-Me2C6H3 (4), 2,6-
i
Pr2C6H3 (5) and 4-
t
Bu-C6H3 (6) in 85–94% yield; and [{OCMeCHCMeN(2,6-
i
Pr2C6H3)}ZnEt]2 (8), [{OCMeCHCMeN(2,6-Me2-C6H3)}ZnEt]2 (7) and [{OCMeCHCMeN(4-
t
Bu-C6H3)}ZnEt]2 (9) in 50–90% yield. 7–9 are mixed with 4–6, respectively, DFT computations of 1H chemical shifts allowed the unambiguous assignment of the species in solution. X-ray single crystal analyses of 4, 6, 7–9 showed that 4 and 6 are bis-chelate complexes in which the coordination geometry about zinc is distorted tetrahedral and overall C2 symmetry. 7–9 are bimetallic complexes in which the coordination geometry about zinc is distorted tetrahedral but with overall S2 symmetry. The optimized geometry of DFT models 4a and 4b (CH2Cl2 as solvent) indicated that the distortion of the geometry in 4 is due in part to the CH2Cl2 present in the unit cell. ROP of rac-LA catalyzed by complexes 4–9 and 8-O
i
Pr was carried out in toluene solutions. All complexes were active but the best results were obtained with 7–9 and 8-O
i
Pr.
