Positive chemical ionization mass spectra of (?6-arene) tricarbonylchromium complexes with ammonia and isobutane

Abstract

The positive chemical ionization mass spectra, with ammonia and isobutane at 0.5 torr of (η6-arene)Cr(CO)3, where arene is C6H5COMe, C6H5COEt, C6H5COC3H7, C6H5COCMe3, 2-MeC6H4COC3H7, C6H5COOMe, C6H5CH2 COEt, C6H5Me and 1,3,5-Me3C6H3 are reported. All these compounds exhibit [M + H]+ as base peak, with isobutane. In the presence of ammonia, [M + NH4]+ is the most abundant ion, when the arene is a ketone or an ester and the addition site is suggested to be the ligand. Conversely [M + H]+ is the base peak when arene is toluene and mesitylene and the protonation site is likely to be the metal atom. In the presence of ammonia, ions such as [M — 3 CO + NH3]+ and [M — 3 CO + 2 NH3]+ are also observed and their abundances strongly depend on the pressure of the reagent gas.