Letter: On the Structure of C2O2+• Generated from C3O2+•
Letter: On the Structure of C2O2+• Generated from C3O2+•
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信件：关于由 C3O2+• 生成的 C2O2+• 的结构
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
John L. Holmes
中科院分区：
文献类型：
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作者：
D. Dawson;H. Chen;John L. Holmes
亲爱的先生，碳、一氧化碳、一氧化碳、二氧化碳和次氧化物C3O2的线性和准线性氧化物，由于其分子闭壳电子基态X~Σ(G)，在室温和压力下是稳定的气体化合物。相比之下，直链的羰基卡宾C2O和乙烯二酮C2 O2具有开壳电子基态X3Σ-(G)，被认为是稳定的，尽管分子非常活跃。用光谱学方法从理论上、实验上表征了羰基卡宾，用从头算方法对亚乙二酮进行了理论研究。中性OCCO的结构为(准)线性(即非环状)，O=C=C=O，激发时可裂解成CO+CO和C2O+O，无论前驱体是什么，m/z28CO+·始终是C2O2无伪迹亚稳态离子(MI)、碰撞诱导解离(CID)和中和-再电离(NR)质量谱的基峰。最近的一项研究表明，中性C2 O2作为一种稳定的中间体存在，其寿命约为中和-再电离(NR)质谱学中中和碰撞电池和重电离碰撞电池之间的渡越时间的数量级(约1μS)。8在观察到C2、C2O和CO2的NR峰的基础上，提出了活性中性C2 O2[X~，a~，A~，...](基态和/或激发态)是在Xe碰撞气体对C2 O2离子的中和过程中产生的，然后又被O2碰撞气体完全解离，在m/z 56，C2O2处没有产生可检测到的恢复信号。有人说，8关于中性C2O2分子的稳定性，上述解释必须保持不确定。通过电子转移到C2O2离子产生瞬时C2O2被认为是未经证实的，尤其是因为C2O2的解离行为尚不清楚。关联规则可以用来预测直接单分子解离产物，这些将在后面讨论。相比之下，Sulzle等人。在方酸生成的C2O2离子的NRMS研究中，考虑了在中和步骤中可能产生稳定的中性C2O2的可能性。根据反式C2O2[X2Πu(2Bu)]离子与线性C2O2[X3Σg-]中性离子几何构型的差异，提出了所有C2O2离子都应中和到中性C2O2分子的解离(即Σg)态(假定为C2O2[b1Σg+]态)，从而无障碍解离成CO[X1Σ+(G)]+CO[X1Σ+(G)].它们的NR谱中的峰归属于C2和C2O，否则结构指示碎片的存在，被认为对其可能的基因有其他解释。9.
Dear Sir The linear and quasi-linear oxides of carbon, carbon monoxide, CO, carbon dioxide, CO 2, and carbon suboxide, C3O2, are stable gaseous compounds at room temperature and pressure due to their molecular closed shell electronic ground state, X ~ Σ(g). In contrast, linear carbonyl carbene, C2O, and ethenedione, C 2O2, have an open shell electronic ground state, X 3Σ–(g), and are believed to be stable, though very reactive molecules. Carbonyl carbene has been characterised theoretically 2 nd experimentally via optical spectroscopy 3,4 and ethenedione has been studied theoretically via b initio molecular orbital calculations. The structure of neutral OCCO is (quasi-)linear (i.e. non-cyclic), O=C=C=O, which when excited can fragment into CO + CO and C 2O + O. Regardless of the precursor, m/z 28 CO+• is always the base peak in artifactfree metastable ion (MI), collision-induced dissociation (CID) and neutralisation–reionisation (NR) mass spectra of C2O2. The presence of neutral C 2O2 as a stable intermediate, possessing a lifetime (about 1 μs) of the order of the transit time between the neutralisation collision cell and the reionisation collision cell in neutralisation–reionisation (NR) mass spectrometry, has been suggested in a recent study. 8 On the basis of the observation of NR peaks corresponding to C 2, C2O and CO2 it was proposed that viable neutral C 2O2[X ~ , a ~ , A ~ , ...] (ground and/or excited state) was produced in the neutralisation of C 2O2 ion by Xe collision gas, only to then undergo completely dissociative reionisation by O 2 collision gas, yielding no detectable recovery signal at m/z 56, C2O2. It was stated, 8 that the above interpretations must remain inconclusive with regard to the stability of the neutral C 2O2 molecule. The production of transient C 2O2 by electron transfer to the C2O2 ion was considered unproven, not least because the dissociation behaviour of C 2O2 is unknown. Correlation rules can be used to predict the direct unimolecular dissociation products and these will be discussed later. In contrast, Sulzle et al. had discounted the possible generation of stable neutral C 2O2 during the neutralisation step in an NRMS study of C 2O2 ion generated from squaric acid. On the basis of the calculated difference in geometry between the trans-bent C 2O2[X 2Πu(2Bu)] ion and the linear C2O2[X 3Σg–] neutral, it was proposed that all C2O2 ions should undergo neutralisation to a dissociative (i.e. Σg) state of the neutral C 2O2 molecule (presumably the C2O2[b 1Σg+] state) leading to a barrier-free dissociation into CO[ X 1Σ+(g)] + CO[X 1Σ+(g)]. The presence of peaks in their NR spectra assigned to C 2 and C2O, otherwise structure indicative fragments, were dismissed as having other explanations for their possible geneses. 9