Disulfide carbon (CS2) and triphenyl phosphine (TPP) were tested as donors for cobalt (Col, Co2, and Co3)catalyzed 1,2-syndiotactic polymerization of butadiene. With CS2, a 1,2-selectivity of 96.8% and syndiotacticity (rr) up to 97% were achieved by Co1-Co3/Al'Bu-3/CS2, yielding highly crystallized polybutadiene resin. Variations on polymerization temperature (0-80 degrees C), catalyst loading, and polymerization time did not significantly affect the 1,2-incorporation and syndiotactic conformation of the resulting polymers, highlighting the excellent 1,2-stereoselectivity of active species stabilized by CS2. With external donor TPP, the formed Co1-Co3/MAO/TPP have regioselectivities of 65.2-89.2% and syndiotacticities of 32.1-65.5%. Thus, an array of polybutadienes differing in chemoenchainment and 1,2-stereoenchainment is accessible with the present cobalt catalysts in combination with different donors. AFM measurements were performed to distinguish the morphology of two types of 1,2-syn-polybutadiene. Elucidation on the plausible role of CS2 and TPP in the stereoselective polymerization reaction was also made.