The invention relates to polymers obtainable by using novel polymerization initiator compounds and optionally chain end modifying agents. The invention further relates to a method of making the initiator compounds and the corresponding polymers, including chain end-modified polymers. The invention, also relates to polymer compositions comprising the polymer of the invention, and further components such, as extender oils, fillers, etc., and to corresponding vulcanized polymer compositions and articles comprising vulcanized parts made from, the vulcanized polymer composition.