Pyridyldiimine ligands having one of the following structures: 1 and pyridyldiimine metal complexes having one of the following structures: 2 for example the Group 4b, 5b, 6b, 7b, and 8 transition metal (M) complexes such as vanadium complexes, are disclosed. The invention also relates to the use of these metal complexes as olefin polymerization or oligomerization catalysts, optionally in combination with metal alumoxane and similar catalyst activators. Certain of these catalysts have been found to possess robust activity as selective oligomerization catalysts, while others of these catalysts act selectively as polymerization catalysts. A method of synthesizing the above-noted ligands using p-toluenesulfonic acid as a catalyst is also disclosed.