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-)
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-)
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DOI：
10.1021/ja983549v
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发表时间：
1999-09-01
影响因子：
15
通讯作者：
Schrock, RR
中科院分区：
文献类型：
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作者：
Baumann, R;Stumpf, R;Schrock, RR
制备了多种含[(i-PTN-o-C6H4)(2)O](2-) （[i-PrNON](2-)）配体的五和六配位钛锆二烷基配合物，其中有[i-PrNON]Ti(CH2CHMe2)(2)、[i-PrNON]Ti(CH2CMe3)(2)、[i-PrNON]Zr(ch2chme3)(2)和[i-PrNON]Zr(CH2CHMe2)(2)。这些物质是{[i-PrNON]Ti(PMe3)(2)}(2)（mu-N-2）、[i-PrNON]Ti(CHCMe3)(PMe3)(2)、[i-PrNON]Zr(CH2CHMe2)(2)（PMe3）和[i-PrNON]Zr(H2C=CMe2)（PMe3)(2)）等配合物的来源。在没有二氮的情况下，[i-PrNON]Ti(CH2CMe3)(2)和Me2PCH2CH2PMe2反应生成（i-PrNC6H4）（i-PrNC6H4O）Ti(dmpe)，这是一个芳基氧键断裂的伪八面体。在所有结构表征的[i-PrNON]（2-）配体完整的配合物中，它采用给体氧原子为平面的聚合物构型。也制备了类似的二烷基配合物[CyNON]MR2 （Cy =环己基；M = Zr, R = Me, Et, i-Bu, CH2CMe3，烯丙基；M = Ti, R = Me, CH2CMe3, i-Bu）。在没有膦的情况下，[i-PrNON]ZT(CH2CH3)(2)的分解被发现以一级方式进行，通过限制速率的β -氢萃取得到瞬时的[i-PrNON]Zr(CH2CH2)，然后由[i-PrNON]Zr(CH2CH3)(2)进行分子间选择性的β -氢转移或乙基转移，从[i-PrNON]Zr(CH2CH3)(2)到[i-PrNON]Zr(CH2CH2)，如H-2和C-13标记研究所表明的那样。在PMe3的存在下，[i-PrNON]ZrR2配合物的分解明显加快。一种PMe3的等价物被提出结合得到伪八面体加合物[i-PrNON]ZrR2(PMe3)，其中两者都；酰基(R)基团相互靠近，从而加速了-氢的提取。与[i-PrNON]（2-）或[CyNON]（2-）配合物中相对不拥挤的配位球一致，活化的二烷基只会低聚l-己烯。已确定结构的化合物包括[i-PrNON]Ti(CH2CHMe2)(2)、[i-PrNON]Zr(H2C=CHMe2)(2)(PMe3)(2)、[i-PrNON]Zr(CH2CMe2)(PMe3)(2) [i-PrNON]Ti(PMe3)(2)](2)（mu-N-2）、[i-PrNON]Ti(CHCMe3)(PMe3)(2)和（i-PrNC6H4）（i-PrNC6H4）（i- prnc6h40）Ti（dmpe）。
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).