Gas-phase reactions of cobalt(III)β-ketoenolates with Brønsted acid reagents

摘要: The gas-phase reactions of a variety 3-substituted pentane-2,4-dionate cobalt(III) complexes formula [Co{MeC(O)CR1C(O)Me}2{MeC(O)CR2C(O)Me}](R1= R2= H a; R1= H, Cl b, Br c, NO2d, SCN e, Me f or Et g; h, i, NO2j, k, l m) with various Bronsted acid systems, e.g.[CH5]+, [t-C4H9]+, [H3]+, [D3]+, [NH4]+ and [ND4]+, were studied by chemical ionization (CIMS) ion-trap mass spectrometry (ITMS). In all cases the following main observed: (i) ion-to-molecule charge transfer formation corresponding molecular ions, [Co{MeC(O)CR1C(O)Me}2{MeC(O)CR2C(O)Me}]˙+; (ii) unprecedented [H2]+(or [D2]+) from gaseous acids to neutral cobalt ions [M+ 2H]+ 2D]+, respectively, which give rise fragmentation [MeC(O)CRC(O)Me + in many cases, are most abundant species; (iii) H+(or D+) H]+ D]+, respectively. ITMS study reaction between ion [Co(acac)2]+(acac = pentane-2,4-dionate) a–g revealed two processes, results radical cations [Co(acac)2{MeC(O)CRC(O)Me}]˙+, largely predominant process leads bimetallic [Co2(acac)4]+ [Co2(acac)3]+, which, according kinetic studies, arise parallel reactions. discussed terms analogies differences gas- solution-phase tris(β-ketoenolato)cobalt(III) acids. preparation g k–m, not previously reported, is described; furthermore, has been obtained higher yields through an alternative one-step synthesis. All new compounds have characterized elemental analysis, 1H NMR spectrometry.