Mixed alkyl isocyanide-1,4-diaza-1,3-butadiene complexes of chromium—II. Secondary-ion, electron impact and chemical-ionization mass spectrometry of the 18-electron species Cr(CO) 3(CNR)(R′-DAB)

• Published in: Polyhedron Vol. 5; no. 8; pp. 1321 - 1328
• Main Authors: Detter, Lisa D., Walton, Richard A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1986; New York, NY Elsevier Science
• Subjects: Carbonyl and nitrosyl metals; Chemistry; Exact sciences and technology; Inorganic chemistry and origins of life; Preparations and properties; Chromium Carbonyl Complexes; Complexes Mixed; Organic ligand; Fragmentation pattern; Negative ion; Transition metal Carbonyl Complexes; Isocyanide; Mass spectrometry; Positive ion
• ISSN: 0277-5387
• DOI: 10.1016/S0277-5387(00)83123-X

Mass analysis of the 18-electron mixed isocyanide-1,4-diaza-1,3-butadiene complexes [Cr(CO) 3(CNR)(R′-DAB)] (R = Me, CHMe 2, CMe 3 or xylyl; R′ = i-Pr, tBu or Cy) was undertaken using secondary-ion mass spectrometry (SIMS), electron impact (EI) mass spectrometry and both positive- and negative-ion chemical-ionization (CI) (PICI and NICI) mass spectrometry. With the exception of the PICI spectra, abundant molecular ions were not present. In all instances, well-defined, structurally informative fragment ions were identified which arise by loss of CO and/or the intact RNC and R′-DAB ligands. Cleavage of the RNC ligands (dealkylation) occurs in the SIMS and EI spectra to give fragment ions containing [Cr(CNH)] +, whereas only in NICI are fragments observed in which the cyano moiety [Cr(CN)] + is present. High-abundance carbonyl-containing fragments are seen only in the case of the CI spectra and are most common in the NICI measurements. These trends are discussed in the light of the Cr-ligand bonding.