IR spectroscopic investigations into reactions between unsaturated titanium complexes and CO or N 2 in liquid xenon or heptane

Abstract

The reactions of Cp∗ 2TiR compounds with CO in liquid xenon (LXe) or heptane were studied by IR spectroscopy in special high-pressure cells. All complexes incorporate a single CO molecule to fill up their coordination sphere, forming Cp∗ 2TiR(CO) intermediates. These species undergo secondary reactions at elevated temperatures, such as disproportionation to Ti(II) and Ti(IV) complexes. The formation of the 18 VE species Cp∗ 2Ti(CO) 2 seems to be the driving force of the observed reactions. A similar behavior was found in the reaction of Cp∗ 2TiH with dinitrogen, where the adduct Cp∗ 2TiH(N 2) and its 14 15 N 2 isotopomer was identified together with Cp∗ 2Ti(N 2) 2. In addition to these orientating experiments, the stable 15 VE Cp∗FvTi (Fv = η 6C 5Me 4CH 2) and 16 VE species Cp∗AdTi (Ad = η 7C 5Me 3(CH 2) 2) show the addition of carbon monoxide to form new, reactive titanium carbonyls, which undergo ligand exchange reactions at higher temperatures and form Cp∗ 2Ti(CO) 2 as one of the final products.