Methods for the Synthesis of the Diels−Alder Catalysts (ArO)₂TiX₂ (X = Cl, Br, I; Ar = 2-tert-Butyl-6-methylphenyl)

Abstract

A procedure for converting titanium diethylamidos to the corresponding dihalides (Cl, Br, I) and a complementary method for converting titanium dichlorides into dibromides and diiodides are reported. These methods were utilized to synthesize a family of homogeneous and polymer-supported Diels−Alder catalysts with the general formula (ArO)2TiX2 (X = Cl, Br, I; Ar = 2-tert-butyl-6-methylphenyl).

Atropisomeric amides: Achiral ligands with chiral conformations

“…53 The titanium phenoxide Ti-O distances in 6a and 6b are between 1.917(1) Å and 1.931(2) Å, which are longer than titanium phenoxide distances in four-coordinate complexes of the type (ArO) 2 TiX 2 (1.7 Å to 1.8 Å). [54][55][56] The titanium phenoxide Ti-O distances in 6a and 6b are longer than the terminal Ti-O distances in the octahedral dimeric [Ti(OPh) 4 (HOPh)] 2 (1.789-1.884 Å), 57 octahedral titanium salen complexes (salen)TiX 2 (X=Me, Cl, OAr), which range from 1.829 Å to 1.899 Å, [58][59][60] and (tetrahydrosalen) Ti(O-iPr) 2 (1.905 Å to 1.914 Å). 61 The titanium amide carbonyl Ti-O bond distances are considerably longer, as expected, and range from 2.142(2) Å to 2.178(2) Å.…”

Titanium complexes containing new dianionic tetradentate [ONNO]-type ligands with benzyl substituents on bridging nitrogen atoms: Syntheses, X-ray structures, and catalytic activities in ring opening polymerization of lactide

“…The small difference between the two coordinative Ti-N bond lengths may indicate a weaker binding of the side arm nitrogen to the titanium center. The Ti-O aryloxy distances in 2, 4, 6, and 7, which range from 1.893(4) to 1.936(2) Å, are longer than those in tetrahedral titanium phenoxide distances such as (ArO) 2 TiX 2 (1.7-1.8 Å) [44][45][46] but similar to those in octahedral titanium complexes containing Salan ligand (1.900(2)-1.930(1) Å) [37,[39][40][41]. The nonequivalency of the two benzylic methylene hydrogens is also apparent from the structure, one being approximately parallel to the aromatic ring and the other being perpendicular to it.…”

Ethylene-linked bis(phenol) ligands: efficient synthesis, Ti(IV) coordination chemistry, and Lewis acid catalysis

“…Scheme 2. unlinked derivatives of tetrahedral (3)TiBr 2 complexes [4,12,13], Thus, the linkage joining the two aryloxy ligands is structurally significant only in the octahedral form of the Lewis acid; the base-free tetrahedral forms are isostructural.…”