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

Dilrukshi Hewage; Wenjin Cao; Jong Hyun Kim; Ya Wang; Yang Liu; Dong-Sheng Yang

doi:10.1021/acs.jpca.6b12239

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

J Phys Chem A. 2017 Feb 16;121(6):1233-1239. doi: 10.1021/acs.jpca.6b12239. Epub 2017 Feb 6.

Authors

Dilrukshi Hewage¹, Wenjin Cao¹, Jong Hyun Kim¹, Ya Wang², Yang Liu², Dong-Sheng Yang¹

Affiliations

¹ Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506-0055, United States.
² MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology , Harbin 150080, China.

PMID: 28124565
DOI: 10.1021/acs.jpca.6b12239

Abstract

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.