Exhaustive Oxidative Decarbonylation of Metal Carbonyls by Light and Oxygen: The Example of (η5-C5Me5)ReO3†
Exhaustive Oxidative Decarbonylation of Metal Carbonyls by Light and Oxygen: The Example of (η5-C5Me5)ReO3†
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光和氧对羰基金属的彻底氧化脱羰：(η5-C5Me5)ReO3† 的示例
DOI：
10.1002/anie.198403831
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发表时间：
1984
影响因子：
--
通讯作者：
H. Bock
中科院分区：
文献类型：
--
作者：
W. Herrmann;R. Serrano;H. Bock
将半夹心配合物1在四氢呋喃(THF)中的溶液在严格排除氧气的条件下(氩气氛或真空、石英玻璃、汞高压灯)照射，可产生THF配合物2的CO消除反应；后者的物质尚未分离，但已从随后与膦发生的反应中确定了其身份。而类似的锰络合物在大气氧气存在下分解，2消除CO和C02(GC)，形成无羰基的产物3，通过柱层析得到空气稳定的柠檬黄可升华晶体，产率高达约40%[‘]。3具有意想不到的单核三氧配合物组成(MS，IR，拉曼，核磁共振)；元素分析和蒸气渗透测定表明，式为CI0Hl5O3Re，只有一个Re原子[4]。3是通过0x0配体氧化取代整组羰基得到的产物1。后者可以通过它们强烈的v(Re=O)伸缩带(IR，拉曼)来识别；五甲基环戊二烯配体的n配位来自于~1H-和~(13)C-核磁共振谱，即使在-120℃(CHFC12)也只显示出简单的信号模式[‘’。在成键理论方面，值得注意的是，1中的金属中心以+1(d6-Re1)的氧化态存在，而3中的金属中心首次以半三明治络合物的形式存在，因为Rev1‘具有DO构型。D-电子记账的这种巨大差异反映在光谱中。因此，CO被0x0基团取代导致在I3C-核磁共振谱中与金属键合的环状配体的C原子急剧脱位(A6>；20ppm)，表明电荷密度显著降低。更令人印象深刻的是，PE光谱令人信服地显示了氧化态的变化：在d6络合物1(图。Lb)中心在8 eV附近的第一组能带被指定为金属d电子的电离，第二组在9.2 eV处被指定为环配体C5的几乎简并的N电离。正如预期的那样，对于三氧杂配合物3，在PE谱的低能区没有发现可能是金属d电子的进一步电离带(图3)。La)[61.初步的X-射线结构分析结果表明，在563，NCP[a]中，环状配体是对称的n键
Irradiation of a solution of the half-sandwich complex 1 in tetrahydrofuran (THF) under rigorous exclusion of oxygen (argon atmosphere or vacuum, quartz glass, Hg highpressure lamp) effects CO-elimination with formation of the THF complex 2; the latter species has not yet been isolated in substance but its identity has been established from subsequent reactions with phosphanes. Whereas analogous manganese complexes decompose in the presence of atmospheric oxygen, 2 eliminates CO and C02 (GC) to form the carbonyl-free product 3, which after work-up by means of column chromatography is obtained as air-stable, lemon yellow, sublimable crystals in up to ca. 40% yield [‘]. 3 has the unexpected constitution of a mononuclear trioxo complex (MS, IR, Raman, NMR); elemental analysis and determination of M, by vapor osmometry indicate the formula CI0Hl5O3Re with only one Re atom [4]. 3 is derived from the educt 1 by oxidative substitution of the entire set of carbonyl groups by 0x0 ligands. The latter can be identified by their intense v (Re= O) stretching bands (IR, Raman); the n-coordination of the pentamethylcyclopentadienyl ligands follows from the ‘H-and I3C-NMR spectra, which even at-120 C (CHFC12) only exhibit simple signal patterns [‘’. In terms of bonding theory, it is significant that the metal center in 1 is present in the oxidation state+ 1 (d6-Re1), but in 3, for the first time in a half-sandwich complex, as ReV1’having a do configuration. This enormous difference in the d-electron bookkeeping is reflected in the spectra. Thus, replacement of the CO by the 0x0 groups leads to a drastic deshielding (A6> 20 ppm) of the C atoms of the ring ligands bonded to the metal in the I3C-NMR spectrum, indicating a markedly reduced charge density. More impressive is that the PE spectra convincingly show the change in oxidation state: In the d6 complex 1 (Fig. lb) the first group of bands centered around 8 eV is assigned to the ionizations of metal d electrons, and the second at 9.2 eV to the almost degenerate n ionizations of the ring ligandc5]. As expected, for the trioxo complex 3 no further ionizations bands which could be assigned to metal d electrons are found in the low energy region of the PE spectrum (Fig. la)[61. The results of a preliminary X-ray structure analysis indicate that the ring ligand is symmetrically n-bonded in the563, ncp [a