New Titanium Complexes with Symmetric or Asymmetric cis-9,10-Dihydrophenanthrenediamide Ligands Formed through Sequential Intramolecular C−C Bond-Forming Reactions

Abstract

A series of new titanium(IV) complexes with symmetric or asymmetric cis-9,10-dihydrophenanthrenediamide ligands, cis-9,10-PhenH(2)(NR)(2)Ti(O(i)Pr)(2) [PhenH(2) = 9,10-dihydrophenanthrene, R = 2,6-(i)Pr(2)C(6)H(3) (2a), 2,6-Et(2)C(6)H(3) (2b), 2,6-Me(2)C(6)H(3) (2c)], cis-9,10-PhenH(2)(NR(1))(NR(2))Ti(O(i)Pr)(2) [R(1) = 2,6-(i)Pr(2)C(6)H(3), R(2) = 2,6-Et(2)C(6)H(3) (2d); R(1) = 2,6-(i)Pr(2)C(6)H(3), R(2) = 2,6-Me(2)C(6)H(3) (2e)], and [cis-9,10-PhenH(2)(NR(1))(2)][o-C(6)H(4)(CH=NR(2))]TiO(i)Pr [R(1) = 2,6-(i)Pr(2)C(6)H(3), R(2) = 2,6-Et(2)C(6)H(3) (3a); R(1) = 2,6-(i)Pr(2)C(6)H(3), 2,6-Me(2)C(6)H(3) (3b)], have been synthesized from the reactions of TiCl(2)(O(i)Pr)(2) with o-C(6)H(4)(CH=NR)Li [R = 2,6-(i)Pr(2)C(6)H(3), 2,6-Et(2)C(6)H(3), 2,6-Me(2)C(6)H(3)]. The symmetric complexes 2a-2c were obtained from the reactions of TiCl(2)(O(i)Pr)(2) with 2 equiv of the corresponding o-C(6)H(4)(CH=NR)Li followed by intramolecular C-C bond-forming reductive elimination and oxidative coupling processes, while the asymmetric complexes 2d-2e were formed from the reaction of TiCl(2)(O(i)Pr)(2) with two different types of o-C(6)H(4)(CH=NR)Li sequentially. The complexes 3a and 3b were also isolated from the reactions for complexes 2d and 2e. All complexes were characterized by (1)H and (13)C NMR spectroscopy, and the molecular structures of 2a, 2b, 2e, and 3a were determined by X-ray crystallography.