摘要
对四价钼系催化丁二烯1,2-聚合中Mo(Ⅳ)络合物的紫外可见光谱进行了研究.MoCl_4乙酸乙酯溶液呈棕红色,显顺磁性.在光谱的紫区和红区共有3个自旋允许d-d跃迁吸收带.Mo(Ⅳ)八面体络合物上各种配体的交换对光谱吸收带位置无影响.Mo(Ⅳ)在512 nm处的特征吸收带随Al(i-Bu)_3/Mo或Al(i-Bu)_2OPh/Mo增加而渐趋消失,这是Mo(Ⅳ)→Mo(Ⅲ)反应的标志.在MoCl_(4-n)·(OC_8H_(17))_n-Bd-Al(i-Bu)_2OPh 3组分陈化体系中Mo(Ⅳ)的还原得到加快,催化聚合活性亦有提高。
MoCl4 in ethyl acetate is of a brown-red color and paramagnetism, which is the result of three absorption bands in the red and blue parts of the spectrum due to the d-d spin-allowed transtition. The change in the types of ligands attached to Mo( Ⅳ ), such as CP, C8H17O- , PhO-, Bd, C8H17OH, PhOH and CH3COOC2H5, has no influence on the position of the absorption band. The peak-value of characteristic absorption band of Mo (Ⅳ) complex at 512 nm varies with the amount of cocatalyst added into Mo-Al system. The disappearance of the characteristic absorption band implies that Mo( Ⅳ ) is reduced to a low-valency state Mo( Ⅲ ). The reduction of Mo(Ⅳ ) is improved and the catalytic activity is raised in the aging catalyst system MoCl4-2(OC8H17)2-Bd-Al(i-Bu)2OPhCH3.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
1991年第2期276-280,共5页
Chemical Journal of Chinese Universities
基金
国家自然科学基金
关键词
四氯化钼
催化
丁二烯
聚合
Ziegler-Natta catalyst, Molybdenum tertrachloride, UV-Vis spectrum, Polybutadiene
