Synthesis of Dipotassium 2,2′‐Bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl Derivatives and Use as Ligand Transfer Reagent

다국어 초록 (Multilingual Abstract)

The condensation of 2,2′‐diamino‐4,4′‐dimethyl‐1,1′‐biphenyl with 2‐hydroxybenzaldehyde (salicylaldehyde) or their 3‐, 4‐ or 5‐methoxy substituted congeners leads to the formation of 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl (1a) and their methoxy‐substituted congeners 1b–1d. Deprotonation of 1a with KH yields octameric and wheel‐shaped dipotassium 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl (2a) that is only very sparingly soluble in common organic solvents. Attached methoxy groups are able to stabilize smaller aggregates and trimeric dipotassium 2,2′‐bis(2‐oxido‐3‐methoxybenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl (2b) has been isolated. The metathesis reaction of 2a with [(thf)2TiCl4] yields 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl titanium(IV) dichloride (3) with two isomeric forms, one with a cis and another with an uncommon trans arrangement of the halide ions.
The coordination behavior of metalated 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl towards potassium and titanium(IV) shows unique peculiarities. The wheel‐shaped potassium salt contains a large void containing toluene molecules. For TiIV, this ligand shows two distinct binding modes; one is very similar to the coordination of classical salen ligands.