Interaction of the 2-(phenyl-2-ol)-6-ketiminopyridines 2-(4′-R 1 -C 6 H 3 -2′-OH)-6-{CMeN(2″,6″-i-Pr 2 C 6 H 3 )}C 5 H 3 N (R 1 = H (L1 a -H), Bu t (L1 b -H), Cl (L1 c -H), F (L1 d -H)) with AlMe 3 at elevated temperature and subsequent crystallization from acetonitrile affords the five-coordinate 2-(phenyl-2-olate)-6-(2-amidoprop-2-yl)pyridine aluminum− methyl complexes [2-(4′-R 1 C 6 H 3 -2′-O)-6-{CMe 2 N(2″,6″-i-Pr 2 C 6 H 3 )}C 5 H 3 N]AlMe(NCMe) (R 1 = H (1a), Bu t (1b), Cl (1c), F (1d)), as their acetonitrile adducts, in good yield. In each case, complexation results in concomitant C−C bond formation via methyl migration from aluminum to the corresponding imino unit in L1-H. On the other hand, reactions of the aldimine-containing compounds 2-, in which the migrated methyl group and aluminum−methyl are disposed mutually cis; evidence for the minor trans isomers 2a′−c′ is presented. The ring-opening polymerization of ε-caprolactone employing 1 and 2 in the presence of PhCH 2 OH proceeded efficiently, producing polymers of narrow molecular weight distribution with the catalytic activities highly dependent on the nature of the phenolate-containing 4-R 1 substituent with the F and Bu t initiators showing the highest activities (1b ≈ 1d > 1a ≈ 1c and 2b > 2a > 2c); in general the CMe 2 -containing series 1 were more active than CH(Me)-containing 2 at 30 °C. The bimetallic complex [{2-(4′-Bu t -C 6 H 3 -2′-O)-6-{CHMeN(2″,6″-i-Pr 2 C 6 H 3 )}C 5 H 3 N}AlMe(μ-OMe)AlMe 2 ] (3), the result of adventitious oxygenation, is also reported. The single-crystal X-ray structures are reported for L1 d -H, L1 f -H, 1a−d, 2a, 2b/2b′, 2c, and 3.

The symmetrical and unsymmetrical pentaaza 2,6-oligopyridylimines, 6,6ЈЈ-[(2,6-iPr 2 C 6 H 3 )N=CMe] 2 -2,2Ј:6Ј,2ЈЈ-C 15 H 9 N 3 (L1) and 6-[(2,6-iPr 2 C 6 H 3 )N=CMe]-2,2Ј:6Ј,2ЈЈ:6ЈЈ,2ЈЈЈ-C 20 H 13 N 4 (L2), have been prepared in good yield using a combination of palladium (0)

Three sterically-enhanced 2-imino-6-(1-naphthyl)pyridines, 2-{CMe=N(Ar)}-6-(1-C10H7)C5H3N [Ar = 2,6-i-Pr2C6H3 (L1dipp), 2,4,6-i-Pr3C6H2 (L1tripp), 4-Br-2,6-i-Pr2C6H2 (L1Brdipp)], differing only in the electronic properties of the N-aryl group, have been prepared in high yield by the condensation reaction of 2-{CMe=O}-6-(1-C10H7)C5H3N with the corresponding aniline. Treatment of L1dipp, L1tripp and L1Brdipp with two equivalents of AlMe3 at elevated temperature affords the distorted tetrahedral 2-(amido-prop-2-yl)-6-(1-naphthyl)pyridine aluminum dimethyl complexes, [2-{CMe2N(Ar)}-6-(1-C10H7)C5H3N]AlMe2 [Ar = 2,6-i-Pr2C6H3 (1a), 2,4,6-i-Pr3C6H2 (1b), 4-Br-2,6-i-Pr2C6H2 (1c)], in good yield. The X-ray structures of 1a-1c reveal that complexation has resulted in concomitant C-C bond formation via methyl migration from aluminum to the corresponding imino carbon in L1aryl; in solution, the restricted rotation of the pendant naphthyl group in 1 confers inequivalent methyl ligand environments. The ring opening polymerization of ε-caprolactone employing 1, in the presence of benzyl alcohol, proceeded efficiently at 30 °C producing polymers of narrow molecular weight distribution with the catalytic activities dependent on the nature of the substituent located at the > 1c); at 50 °C 1b mediates 100% conversion of the monomer to polycaprolactone (poly(CL)) in one hour. In addition to 1a, 1b and 1c, the single crystal X-ray structures are reported for L1dipp and L1tripp.