.alpha.-Elimination Can Be Faster than .beta.-Elimination in d2 Alkyl Complexes of Molybdenum and Tungsten That Contain the Trimethylsilyl-Substituted Triamidoamine Ligand
.alpha.-Elimination Can Be Faster than .beta.-Elimination in d2 Alkyl Complexes of Molybdenum and Tungsten That Contain the Trimethylsilyl-Substituted Triamidoamine Ligand
复制标题
在含有三甲基甲硅烷基取代的三酰氨基胺配体的钼和钨的d2烷基络合物中，α-消除可以比β-消除更快
DOI：
10.1021/ja00129a032
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发表时间：
1995
影响因子：
15
通讯作者：
W. M. Davis
中科院分区：
文献类型：
--
作者：
R. Schrock;K. Shih;Daniel A. Dobbs;W. M. Davis
含三酰胺胺配体的过渡金属配合物的反应特性已开始探索。2 '14我们最近公开了含有[（Me.1SiNCFUCFDbN] 111'（[N3 N] 3-）配体13的MoK和W 9络合物的一些不寻常的反应，其包括（阿利亚）从W烷基损失分子氢以得到次烷基络合物。本文表明，当α，α-脱氢被环戊基配体阻断时，可观察到α-消除反应生成W（而不是Mo）的烷叉氢化物配合物，以及最终的β-消除反应生成稳定的Mo和W的顺磁性单氢化物配合物。将环戊基锂加入到乙醚中的[N3 N] WC 19中，定量地产生氯化锂和戊烷可溶的黄色结晶络合物。X射线研究16（图1）表明它是18电子的“7-环戊叉氢化物络合物，[N3 N] W（CXHs）（H）。亚环戊基配体的取向使其（大约）位于穿过W、N（5）和N（8）的平面内，使N（6）和N（7）稍微分开（125.7与112.4和105.4）。在离金属约1.81埃的平面上也发现了氢化物配位体的电子密度，但它不能经受住细化。由于yHW= 89 Hz，C（9）-·-H= 2.43 A，N（5）-·-H= 1.68 A，且C（9）和N（5）上的p轨道垂直于C（9）-W-H-N（5）平面，因此H与C（9）或N（5）之间似乎没有任何显著的相互作用。亚环戊基配体的位置和观察到的取向与三个可用的成键轨道的性质一致，约为dv：，dv;和a杂化，沿着z（W-Nd_m> r）轴指向。图17两种Cr键合杂化物的形成
Reactivity characteristics of transition metal complexes that contain triamidoamine ligands' are beginning to be explored. 2'14 We recently published some unusual reactions of MoK and W9 complexes containing the [(Me. iSiNCFUCFDbN] 1 11'([N3N] 3~) ligand13 that included (inter alia) loss of molecular hydrogen from W alkyls to give alkylidyne complexes. We show here that when a, a-dehydrogenation is blocked (by employing a cyclopentyl ligand), a-elimination to give an alkylidene hydride complex of W (but not one of Mo) as well as eventual/3-elimination to give stable paramagnetic monohydride com-plexes of both Mo and W can be observed. Addition of cyclopentyllithium to [N3N] WC19 in diethyl ether yields lithium chloride and a pentane-soluble yellow crystalline complex quantitatively. An X-ray study16 (Figure 1) shows it to be the 18-electron'7cyclopentylidene hydride complex,[N3N] W (CXHs)(H). The cyclopentylidene ligand is oriented so that it lies (approximately) in a plane that passes through W, N (5), and N (8), spreading N (6) and N (7) apart slightly (125.7 versus 112.4 and 105.4). Electron density ascribable to the hydride ligand also was found approximately in this plane 1.81 A from the metal, butit would not survive refinement. Since yHW= 89 Hz, C (9)-•-H= 2.43 A, N (5>•-H= 1.68 A, and the p orbitals on C (9) and N (5) are oriented perpendicular to the C (9)—W—H—N (5) plane, there does not appear to be any significant interactionbetween H and either C (9) or N (5). The position and observed orientation of the cyclopentylidene ligand are consistent with thenature of the three available bonding orbitals, approximately dv:, dv;, and a a hybrid pointing along the z (W-Nd „m> r)-axis. 17 Formation of two cr-bonding hybrid