Spectroscopic Characterization of Nonconcerted [4 + 2] Cycloaddition of 1,3-Butadiene with Lanthanacyclopropene To Form Lanthanum–Benzene in the Gas Phase

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• 作者：Dilrukshi Hewage ; Wenjin Cao ; Jong Hyun Kim ; Ya Wang ; Yang Liu ; Dong-Sheng Yang
• 刊名：Journal of Physical Chemistry A
• 出版年：2017
• 出版时间：February 16, 2017
• 年：2017
• 卷：121
• 期：6
• 页码：1233-1239
• 全文大小：392K
• ISSN：1520-5215

文摘

The reaction between La atoms and 1,3-butadiene is carried out in a laser-vaporization molecular beam source. Metal–hydrocarbon species with formulas La(C_nH_n) (n = 2, 4, and 6) and La(C_mH_m+2) (m = 4 and 6) are observed with time-of-flight mass spectrometry and characterized with mass-analyzed threshold ionization spectroscopy. A lanthanum–benzene complex [La(C₆H₆)] is formed by 1,3-butadiene addition to lanthanacyclopropene [La(C₂H₂)] followed by molecular hydrogen elimination. Lanthanacyclopropene is an intermediate generated by the primary reaction between La and 1,3-butadiene. Two other intermediates produced by the La + 1,3-butadiene reaction are La[η⁴-(1-buten-3-yne)] [La(C₄H₄)] and 1-lanthanacyclopent-3-ene [La(C₄H₆)]. The La(benzene) complex exhibits distinctive metal–ligand bonding from that of the three intermediates as shown by the adiabatic ionization energies and ground electron configurations.