PROTONS ON A CLUSTER SURFACE. REVERSIBLE GENERATION OF AGOSTIC (CARBON-HYDROGEN-METAL) HYDROGENS FROM IRON HYDRIDES (IRON-HYDROGEN-IRON) ON A SATURATED TRIIRON CLUSTER
PROTONS ON A CLUSTER SURFACE. REVERSIBLE GENERATION OF AGOSTIC (CARBON-HYDROGEN-METAL) HYDROGENS FROM IRON HYDRIDES (IRON-HYDROGEN-IRON) ON A SATURATED TRIIRON CLUSTER
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簇表面上的质子。
DOI：
10.1002/chin.198552271
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
T. Fehlner
中科院分区：
文献类型：
--
作者：
J. Vites;G. Jacobsen;T. Dutta;T. Fehlner
在去质子化时这种迁移率的增加使我们研究了伊利亚和伊利卜在去质子化时的行为。结果表明，在iLIA的去质子化过程中，Fe-H-Fe相互作用净转化为CH-Fe相互作用，在再质子化过程中则相反。相反，Illb的去质子化导致氢的消除和亚乙烯团簇阴离子的形成。这些都是饱和体系，我们认为相对电荷效应在控制金属团簇中CHM相互作用的形成和破坏方面是重要的。对ITIA进行了去质子化以形成PPN(双三苯基膦亚胺)盐5 6，如预期的那样，红外光谱表明分子的对称性低于CJD--然而，在低温下的*H核磁共振(图1)显示了三种类型的质子，其中一种不可能来自于从ITIA简单地去除质子而得到的结构，除非氢被重排。也就是说，在6.6和-20.3处的共振可以归因于像Ilia这样的结构上的CH和FeHFe质子，而在-10.1处则不能。这种化学位移既允许末端FeH，也允许末端氢气。然而，13CH偶合常数强烈地有利于后者。此外，6.6和-10.1共振呈现18-HZ分裂，选择性解耦证明这是由于双HH耦合。这是该阴离子中含有CH2单元的有力证据。因此，我们建议结构V为阴离子的结构，7**Ie，一个不对称结合的CH2片段，覆盖在金属三角上。在去质子化过程中，Fe-H-Fe相互作用转变为CH-Fe相互作用。在需要类似结构V的中间态或过渡态的三金属体系中的团簇重排已经被(5)乙叉衍生物Illb完整地描述了。书名：T.PJ Am化学。SoC。1981、103、966年。书名/作者声明/作者声明：//by J.化学。1982年、21日、3197年。L；王国生；费尔纳，T.P.(6)在四氢呋喃(NaHB(OCH_3)_3与Fe(CO)_3反应生成的四氢呋喃中，加入4摩尔铁(CO)S和四氢化硼四氢呋喃(BH_3THF)，在25℃下反应1h，得到一种烷基阴离子混合物。除去溶剂，然后用磷酸酸化，然后用正己烷萃取，就得到了中性碳氢簇的混合物。在硅胶上用iLiA和iva，b去质子化，柱层析后用甲醇洗脱，酸化后的洗脱液在酸性条件下进行离心薄层层析，得0.2
V VI VII on I and II and the increase in this mobility on deprotonation has led us to examine the behavior of Ilia and Illb on deprotonation. The results demonstrate the net conversion of an Fe-H-Fe interaction to a CH-Fe interaction on deprotonation of Ilia and the reverse on reprotonation. In contrast, deprotonation of Illb results in H2 elimination and theformation of a vinylidene cluster anion. These being saturated systems, we suggest relative charge effects are important in controlling the formation and destruction of CHM interactions in metalclusters. Deprotonation of Ilia to form the PPN (bistriphenyl-phosphineiminium) salt was carried out5 6 and, as expected, the infrared spectrum indicates molecular symmetry lower than Cjd-Unexpectedly, however, the* H NMR at low temperature (Figure 1) exhibits three types of protons, one of which cannot result from a structure derived by simple proton removal from Ilia unless the hydrogens are rearranged. That is, the resonances at 6.6 and-20.3 can be attributed to CH and FeHFe protons on a structure like Ilia but that at-10.1 cannot. This chemical shift permits either a terminal FeH or an agostic2 hydrogen. However, the 13CH coupling constant strongly favors the latter. In addition, the 6.6 and-10.1 resonances exhibit an 18-Hz splitting, which was demonstrated by selective decoupling to be due to geminal HH coupling. This is strong evidence for a CH2 unit in thisanion. Thus, we suggest structure V as the structure of the anion, 7** ie, an asymmetrically bound CH2 fragment capping the metal tri-angle. On deprotonation, then, an Fe-H-Fe interaction has been converted into a CH-Fe interaction. Cluster rearrangements in trimetal systems that require an intermediate or transition state similar to structureV have been (5) The ethylidyne derivative Illb has been fully described. Wong, K. S.; Fehlner, T. PJ Am. Chem. Soc. 1981, 103, 966. Wong, K. S.; Haller, K. J.; Dutta, TK; Chipman, D. M.; Fehlner, T. P. Inorg. Chem. 1982, 21, 3197. DeKock, R. L; Wong, K. S.; Fehlner, T. P. Ibid. 1982, 21, 3203.(6) Treatment of 2 mmol of [(CO) 4FeC (0) H] Na in THF (formed in situ by the reaction of NaHB (OCH3) 3 with Fe (CO)¡,) with 4 mmol of Fe (CO) s and 4 mmol of commercial BH3THF at 25 C for 1 h yielded a mixture of hydrocarbyl anions. Removal of the solvent followed by acidification with phosphoric acid and extraction with hexane yielded a mixture of neutral hydrocarbyl clusters. As Ilia and IVa, b deprotonate on silica gel, column chromatography followed by elution with CH3OH and centrifugal thin-layer chromatography on the acidified eluate under acidic conditions yielded 0.2