OXAZOLINE EARLY TRANSITION-METAL COMPLEXES - FUNCTIONALIZABLE ACHIRAL TITANIUM(IV), TITANIUM(III), ZIRCONIUM(IV), VANADIUM(III), AND CHIRAL ZIRCONIUM(IV) BIS(OXAZOLINE) COMPLEXES

Large-scale syntheses of the (hydroxyphenyl)oxazoline ligands L(1) = 6, L(2) = 7, L(3) = 8, L(4) = 9, and L(5) = 10 are reported. The conversion of 6-10 into the corresponding sodium salts has been employed for metal complexation. The reaction of 6 with TiCl4 . 2THF, TiCl3 . 3THF, ZrCl4 . 2THF, and VCl3 . 3THF in a 1:2 metal:ligand ratio afforded the corresponding hexacoordinate functionalizable metal complexes: cis-[(Cl)(2)Ti(L(1))(2)], 11; cis-[(THF)(Cl)Ti-(L(1))(2)], cis-[(Cl)(2)Zr(L(1))(2)], 13; trans-[(THF)(Cl)V(L(1))(2)], 14. The structures of 11, 12, and 14 have been clarified by X-ray analysis. The reaction of the 8 and 9 sodium salts with ZrCl4 . 2THF in a 1:2 metal:ligand ratio led to the corresponding chiral functionalizable metal complexes, whose structures were clarified by X-ray analysis: cis-[(Cl)(2)Zr(L(3))(2)], 15; cis-[(Cl)(2)Zr(L(4))(2)], 16. A common significant feature discovered from these studies is the existence of intramolecular hydrogen bonding, which is probably responsible for the high conformational rigidity of the oxazoline ligand. Crystallographic details are as follows: 11 is monoclinic, space group I2/a, with a = 16.443(2) Angstrom, b = 8.365(1) Angstrom, c = 17.945(2) Angstrom, beta = 106.93(1)degrees, Z = 4, and R = 0.034; 12 is orthorhombic, space group Pca2(1) with a = 15.669(2) Angstrom, b = 17.750(3) Angstrom, c = 18.971(3) Angstrom, Z = 8, and R = 0.050; 14 is monoclinic, space group P2(1)/n, with a = 9.391(4) Angstrom, b = 28.618(6) Angstrom, c = 12.077(4) Angstrom, beta = 105.79(2)degrees, Z = 4, and R = 0.052; 16 is monoclinic, space group P2(1), with a = 10.161(2) Angstrom, b = 14.151(3) Angstrom, c = 12.361(2) Angstrom, beta = 93.76(2)degrees, Z = 2, and R = 0.033.