Gas chromatographic separation of PF3 substituted group 6 metal carbonyl complexes using serially-coupled capillary columns

The retention of group 6 metal trifluorophosphine carbonyl compounds in serially-coupled gas capillary columns has been studied as a function of different column configurations. For the trifluorophosphine-substituted Mo, W, and Cr carbonyls, as well as the analogous Fe compounds, it was observed that the maximum resolution achievable by the coupled column technique was dependent on the order in which the nonpolar (DB-1) and moderately polar (DB-1701) columns were connected. The optimum configuration was different, however, for each series M(PF₃)_x(CO)_6?x(M = Cr, Mo, or W) or Fe(PF₃)_x(CO)_5?x. It was also observed that the use of coupled columns of dissimilar polarity can, in some cases, actually decrease resolution relative to that obtained by coupled identical columns (i. e. DB-1 + DB-1, or DB-1701 + DB-1701).