Millimeter-wave spectroscopy of CrC (X3Σ−) and CrCCH (X̃ 6Σ+): Examining the chromium-carbon bond
AffiliationUniv Arizona, Steward Observ, Dept Astron, Dept Chem & Biochem
MetadataShow full item record
PublisherAMER INST PHYSICS
CitationMillimeter-wave spectroscopy of CrC (X3Σ−) and CrCCH (X̃ 6Σ+): Examining the chromium-carbon bond 2016, 144 (18):184308 The Journal of Chemical Physics
JournalThe Journal of Chemical Physics
Rights© 2016 Author(s). Published by AIP Publishing.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractPure rotational spectroscopy of the CrC (X-3 Sigma(-)) and CrCCH ((X) over tilde (6)Sigma(+)) radicals has been conducted using millimeter/sub-millimeter direct absorption methods in the frequency range 225-585 GHz. These species were created in an AC discharge of Cr(CO)(6) and either methane or acetylene, diluted in argon. Spectra of the CrCCD were also recorded for the first time using deuterated acetylene as the carbon precursor. Seven rotational transitions of CrC were measured, each consisting of three widely spaced, fine structure components, arising from spin-spin and spin-rotation interactions. Eleven rotational transitions were recorded for CrCCH and five for CrCCD; each transition in these cases was composed of a distinct fine structure sextet. These measurements confirm the respective (3)Sigma(-) and (6)Sigma(+) ground electronic states of these radicals, as indicated from optical studies. The data were analyzed using a Hund's case (b) Hamiltonian, and rotational, spin-spin, and spin-rotation constants have been accurately determined for all three species. The spectroscopic parameters for CrC were significantly revised from previous optical work, while those for CrCCH are in excellent agreement; completely new constants were established for CrCCD. The chromium-carbon bond length for CrC was calculated to be 1.631 angstrom, while that in CrCCH was found to be r(Cr-C) = 1.993 angstrom - significantly longer. This result suggests that a single Cr-C bond is present in CrCCH, preserving the acetylenic structure of the ligand, while a triple bond exists in CrC. Analysis of the spin constants suggests that CrC has a nearby excited (1)Sigma(+) state lying similar to 16 900 cm(-1) higher in energy, and CrCCH has a (6)Pi excited state with E similar to 4800 cm(-1). Published by AIP Publishing.
NotePublished online 13 May 2016. 12 month embargo.
VersionFinal published version
SponsorsNSF [AST-1211502, AST-1515568, CHE-1057924]