Structures, Dynamics, and Reactivity of Tripodal Amido Ligands Coordinated to Ti^IV Centres

Abstract

Abstract A new class of amido titanium(IV) halides containing tripodal ligands H 3 CC(CH 2 NR) 3 TiX (R = Me, X = Cl: 1 ; R = Me 3 Si, X = Cl: 2a , Br: 2b ; R = SiMe 2 t Bu, X = Cl: 3a , Br: 3b ) has been synthesised. Compound 1 has been structurally characterised by X‐ray crystallography and found to be dimeric in the crystal displaying an idealised C 2 symmetry with bridging amido functions linking the two halves of the molecule. The dimeric structure is retained in solution as has been shown by 1 H‐ and 13 C‐NMR spectroscopy which has also revealed a high degree of ligand dynamics, effecting the interconversion of the two enantiomeric forms of the molecule. This process has been investigated by variable temperature NMR studies and phase‐sensitive 1 H‐NOESY/EXSY spectra. The dimeric μ‐imido complexes [H 3 CC(CH 2 NSiMe 3 ) 2 (H)CH 2 NTiX] 2 (X = Cl: 4a , Br: 4b ) have been isolated as a byproduct in the synthesis of 2a/b , and a single‐crystal X‐ray structure analysis of 4a has established its molecular structure.