Improved suspensions of transition metal complexes of 2,6-diacylpyridine(bisimines) or 2,6-pyridinedicarboxaldehyde(bisimines), which are useful in catalysts for the polymerization or oligomerization of olefins, are prepared by sonicating a mixture of one or more of these complexes and an inert liquid. The resulting suspensions can be directly used as olefin polymerization or oligomerization catalyst components in oligomerization or polymerization processes. These processes may produce, for example, polyolefins useful for molding resins or films, or linear -olefins.