Synthesis, structures and DFT studies of imido-bridged and (Bis)ligand-coordinated titanium complexes

摘要

Syntheses and structures of five imido-bridged dinuclear titanium complexes and two (bis)ligand-coordinated mononuclear titanium complexes are reported. Addition of 1 or 2 equiv. of Schiff base ligand (((1H-pyrrol-2-yl)methylene) amino)-2,3-dihydro-1H-inden-2-ol (H_2L) to Ti(NMe_2)__ 4 resulted in transamination with 4 equiv. of dimethylamides generating a (bis)ligand-coordinated complex Ti(L)_2 (1). Treatment of Ti(NMe_2)_4 with 1 equiv. of ~tBuNH_2 followed by addition of 1 equiv. of H_2L afforded an imido-bridged complex [Ti(L)(N~tBu)]_2 (2). 1:1:1:1 reaction of Ti(NMe_2)_4/RNH_2/H_2L/py(or phen) produced imido-bridgedcomplexes [Ti(L)(NPh)(py)]_2 (3), [Ti(L)(4-F-PhN)(py)]_2·Tol (4·Tol), [Ti(L)(4-Cl-PhN)(py) ]_2·Tol·THF (5·Tol·THF), [Ti(L)(4-Br-PhN)(py)]_2·Tol (6·Tol) and a (bis)ligand-coordinated complex Ti(L)_2·phen (7) (py = pyridine, phen = 1,10-phenanthroline). Attempts to prepare the monomeric titianium imido complexes were unsuccessful. DFT studies show that the assumed compound which contains Ti = N species is less stable than imido-bridged Ti-N(R)-Ti complexes, providing the better understanding of the experimental results.