A novel class of organic phosphates were synthesized and applied in iron catalyst as additive for 1,2-syndiotactic polymerization of 1,3-butadiene in combination with aluminum alkyls (Ali-Bu3 or AlEt3) in hexane at industrial favorable 50-100 degrees C. Remarkable enhanced polymer productivity (up to 486 kg (polymer)/mol(Fe)h) and excellent 1,2-syndiotactic regularity have been achieved at 50-100 degrees C in all examing cases. All the polymers obtained under various polymerization conditions possess prevailingly 1,2 inserted homo-sequences up to 94.7% 1,2-selectivity in syndiotactic arrangements (up to 94.4%, denoted by rrrr) with melting point ranging from 170 to 182 degrees C. The current in-situ generated catalyst systems feature high productivity, selectivity, robustness (e.g. high thermal stability, good tolerance to poisons and environmentally friendly hexane as solution polymerization medium) and single-site behaviour. These all extend the practical usefulness of these versatile phosphates assisted catalyst, and they are promising candidates to act as ancillary additive for industrial applicable 1,2-syndiotactic polymerization of 1,3-butadiene. (C) 2016 Elsevier Ltd. All rights reserved.