Titanium and zirconium complexes that contain the tridentate diamido ligands [(i-PrN-o-C6H4)2O]2- ([i-PrNON]2-) and [(C6H11N-o-C6H4)2O]2- ([CyNON]2-)

A variety of five- and six-coordinate titanium and zirconium dialkyl complexes that contain the [(i-PTN-o-C6H4)(2)O](2-) ([i-PrNON](2-)) Ligand have been prepared, among them [i-PrNON]Ti(CH2CHMe2)(2), [i-PrNoN]Ti(CH2CMe3)(2), [i-PrNON]Zr(CH2CH3)(2), and [i-PrNON]Zr(CH2CHMe2)(2). These species serve as sources of complexes such as {[i-PrNON]Ti(PMe3)(2)}(2)(mu-N-2), [i-PrNON]Ti(CHCMe3)(PMe3)(2), [i-PrNON]Zr(CH2CHMe2)(2)(PMe3), and [i-PrNON]Zr(H2C=CMe2)(PMe3)(2). The reaction between [i-PrNON]Ti(CH2CMe3)(2) and Me2PCH2CH2PMe2 in the absence of dinitrogen yields (i-PrNC6H4)(i-PrNC6H4O)Ti(dmpe), a pseudooctahedral species in which one aryl-oxygen bond has been cleaved. In all structurally characterized complexes in which the [i-PrNON](2-) ligand is intact, it adopts a mer configuration in which the donor oxygen atom is planar. Analogous dialkyl complexes [CyNON]MR2 (Cy = cyclohexyl; M = Zr, R = Me, Et, i-Bu, CH2CMe3, allyl; M = Ti, R = Me, CH2CMe3, i-Bu) have also been prepared. Decomposition of [i-PrNON]ZT(CH2CH3)(2) in the absence of phosphine has been found to proceed in a first-order manner to yield {[i-PrNoN]Zr(CH2CH3)}(2)(mu-C2H4) via rate-limiting beta-hydrogen abstraction to give transient [i-PrNON]Zr(CH2CH2) followed by either intermolecular selective beta-hydrogen transfer or ethyl group transfer from [i-PrNON]Zr(CH2CH3)(2) to [i-PrNON]Zr(CH2CH2), as suggested by H-2 and C-13 labeling studies. Decompositions of [i-PrNON]ZrR2 complexes are dramatically accelerated in the presence of PMe3. One equivalent of PMe3 is proposed to bind to give a pseudooctahedral adduct, [i-PrNON]ZrR2(PMe3), in which the two all;yl (R) groups are pushed close to one another and beta-hydrogen abstraction is thereby accelerated. Consistent with the relatively uncrowded coordination sphere in [i-PrNON](2-) or [CyNON](2-) complexes, activated dialkyls will only oligomerize l-hexene. Compounds whose structures have been determined include [i-PrNON]Ti(CH2CHMe2)(2), [i-PrNON]ZrMe2, [i-PrNoN]Zr(H2C=CHMe2)(2)(PMe3), [i-PrNON]Zr(CH2CMe2)(PMe3)(2) [i-PrNON]Ti(PMe3)(2)](2)(mu-N-2),[i-PrNON]Ti(CHCMe3)(PMe3)(2), and (i-PrNC6H4)(i-PrNC6H4O)Ti(dmpe).