ARYLTITANIUM(IV) COMPLEXES WITH THE ETA(3)-C,N,N'-PSEUDOFACIALLY COORDINATING LIGAND [C6H4(CH2N(ME)CH2CH2NME2)-2](-) - THE X-RAY CRYSTAL-STRUCTURE OF [TICL2(CNN)(O-I-PR)]

Reaction of [TiCl3(O-i-Pr)] with [Li(CNN)](2) (CNN = monoanionic C6H4( CH2N(Me)CH2CH2NMe2)-2) in 2:1 molar ratio in toluene at -78 degrees C afforded [TiCl2(CNN)(O-i-Pr)] as a 3:2 molar mixture of two stereoisom ers. The stereoisomers differ by the mutual position of the chloro and alkoxy ligands. Molecular modelling calculations and an X-ray analysi s of one of the stereoisomers indicated that the alkoxy ligand exhibit s a strong trans preference to the weakest rr-donating ligated atom, i .e., the N(Me-2) atom of the CNN ligand. The molecular structure of th is stereoisomer, as determined by X-ray analysis, involves an octahedr al titanium center with an eta(3)-fac-C,N,N'-bonded CNN ligand. A stro ng M-O(alkoxy) interaction is illustrated by an almost linear M-O-C bo nd angle of 172.4(2)degrees. As a result of the pseudofacially bonded CNN ligand, the titanium center as well as the central N-donor center are stereogenic resulting in the formation of two enantiomers. A (CNN) titanium(IV) dimethyl complex is accessible via reaction of 1 with two equivalents of MeLi and contains likewise an eta(3)-fac-C,N,N'-bonded CNN ligand. (C) 1997 Elsevier Science S.A.