Preparation of homo- and heterobimetallic .mu.-.eta.2-(C,C)-ketene complexes, FpCH2COMLn, and transformation of the bridging ketene ligand into various C2 functional groups
Preparation of homo- and heterobimetallic .mu.-.eta.2-(C,C)-ketene complexes, FpCH2COMLn, and transformation of the bridging ketene ligand into various C2 functional groups
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DOI：
10.1021/om00092a019
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发表时间：
1988-02
期刊：
影响因子：
2.8
通讯作者：
M. Akita;Atsuo Kondoh;T. Kawahara;Takenobu. Takagi;Y. Moro-oka
中科院分区：
文献类型：
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作者：
M. Akita;Atsuo Kondoh;T. Kawahara;Takenobu. Takagi;Y. Moro-oka
通过用各种过渡金属阴离子酰化铁取代的乙酰氯，制备了八种同-和杂-β-烯酮络合物FpCH 2COML n [3-7：Fp=（5-C5 H6）Fe（CO）2; M= Fe、Mo、Ni、Mn、Co; L= Cp、CO、PR 3]。红外光谱研究表明，除了一个氧卡宾结构FpCH_2C（0 ~）= Fp+（11）外，α-配合物Fp+[CH_2 = C（0 ~）Fp]（10）也有重要贡献。作为一个典型的例子，FpCH 2COFp（3a）经历与催化CO氢化相关的化学转化。虽然3a不容易羰基化以产生μ-丙二酰络合物，但脱羰基导致乙烯酮分子或配体取代的定量释放，而不是形成μ-亚甲基络合物。用LiAlH_4还原3a得到C_3产物作为主要组分。3a与亲电试剂在酰基氧原子处发生反应，得到阳离子双核氧卡宾配合物FpCH 2C（OR）= Fp+ TfO-（TfO= CF 3SO 3）（18-20），其对亲核试剂和亲电试剂表现出双峰反应性。硬亲核试剂攻击最亲电的卡宾中心，软亲核试剂攻击烷基侧Fp基团，亲电反应发生在亚甲基末端。
Eight examples of homo-and heterobimetallic µ-ketene complexes, FpCH2COML „[3-7: Fp=(5-C5H6) Fe (CO) 2; M= Fe, Mo, Ni, Mn, Co; L= Cp, CO, PR3], are prepared by acylation of an iron-substituted acetyl chloride with various transition-metal anions. IR studies reveal the significantcontribution of a-complex Fp+[CH2= C (0~) Fp](10) in addition to an oxycarbene structure FpCH2C (0~)= Fp+(11) which is well-established for mononuclear acyl complexes. As a typical example, FpCH2COFp (3a) is subjected to chemical transformations relevant to catalytic CO hydrogenation. While 3a is not susceptible to carbonylation to lead to a µ-malonyl complex, decarbonylation results in quantitative liberation of ketene molecule or ligand substitution instead of formation of a µ-methylene complex. Reduction of 3a by LiAlH4 affords C3 products as major components. Reaction of 3a with electrophiles takes place at the acyl oxygen atom to give cationic binuclear oxycarbene complexes FpCH2C (OR)= Fp+ TfO"(TfO= CF3S03)(18-20) which exhibit bimodal reactivities toward both nucleophiles and electrophiles. Hard nucleophiles attack the most electrophilic carbene center, soft nucleophiles attack the alkyl side Fp group, and electrophilic reaction takes place at the methylene terminus.