Methane activation by laser-ablated V, Nb, and Ta atoms: Formation of CH3-MH, CH2=MH2, CHMH3-, and (CH3)2MH2.
Methane activation by group 5 transition-metal atoms in excess argon and the matrix infrared spectra of reaction products have been investigated. Vanadium forms only the monohydrido methyl complex (CH3-VH) in reaction with CH4 and upon irradiation. On the other hand, the heavier metals form methyl hydride and methylidene dihydride complexes (CH3-MH and CH2=MH2) along with the methylidyne trihydride anion complexes (CHMH3-). The neutral products, particularly the methylidene complex, increase markedly on irradiation whereas the anionic product depletes upon UV irradiation or addition of a trace of CCl4 or CBr4 to trap electrons. Other absorptions that emerge on irradiation and annealing increase markedly at higher precursor concentration and are attributed to a higher-order product ((CH3)2MH2)). Spectroscopic evidence suggests that the agostic Nb and Ta methylidene dihydride complexes have two identical metal-hydrogen bonds.
Department of Chemistry, University of Incheon, 177 Dohwa-dong, Nam-ku, Incheon 402-749, South Korea.
Han-Gook
HG
Cho
Lester
L
Andrews
D001128:Argon / Q000737:chemistry; D007834:Lasers; D008697:Methane / Q000737:chemistry* / Q000528:radiation effects; D009556:Niobium / Q000737:chemistry* / Q000528:radiation effects; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000528:radiation effects*; D013635:Tantalum / Q000737:chemistry* / Q000528:radiation effects; D014466:Ultraviolet Rays; D014639:Vanadium / Q000737:chemistry* / Q000528:radiation effects
D009942:Organometallic Compounds; D014639:Vanadium; D009556:Niobium; D013635:Tantalum; D001128:Argon; D008697:Methane