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Reactions of Th and U Atoms with C 2 H 2 : Infrared Spectra and Relativistic Calculations of the Metallacyclopropene, Actinide Insertion, and Ethynyl Products
Author(s) -
Andrews Lester,
Kushto Gary P.,
Marsden Colin J.
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600075
Subject(s) - actinide , chemistry , ground state , acetylene , argon , atomic physics , metal , relativistic quantum chemistry , configuration interaction , atomic orbital , hydride , spectral line , excited state , inorganic chemistry , electron , physics , nuclear physics , organic chemistry , astronomy
Reactions of laser‐ablated Th and U atoms with C 2 H 2 during condensation with excess argon at 7 K give several new product species. The metallacyclopropene, inserted hydride, and actinide ethynyl are identified from isotopic frequencies and relativistic DFT calculations. The higher‐energy vinylidine isomer was not observed. These actinide metallacyclopropenes exhibit substantially stronger bonding interactions than found recently for the Pd and Pt metals. In the case of Th(C 2 H 2 ) the argon matrix interaction is strong enough to reverse the computed order of states (MR‐CISD) in favor of a triplet ground state for the (Ar) n (Th(C 2 H 2 )) complex. The nature of the electronic interactions between various metal atoms and acetylene is compared and the origin of the particularly strong interaction for U and Th is traced to the higher energy of their 6d orbitals. The ThCCH and UCCH actinide ethynyl products are also observed and characterized by CC stretching modes 38±2 cm −1 lower than acetylene itself.