双冠醚研究 Ⅷ.席夫碱型双冠醚苦味酸铷配合物的合成及其晶体结构

BIS-CROWN ETHER Ⅷ. SYNTHESIS AND STRUCTURE OF COMPLEX OF THE SCHIFF BASE TYPE BIS CROWN ETHER WITH RUBIDIUM PICRATE

本文合成了间亚苯基桥接的席夫碱型双-(苯并15-冠-5)苦味酸铷配合物以及测定了其晶体结构。实验证明该晶体属单斜晶系,P2_1/n空间群,晶胞参数:a=19.3049(49)(?),b=20.4544(39)(?),c=25.4375(75)(?),β=107.925(21)°,V=9556.90(?)~3,F(000)=4175.41(e),Dc=1.455g/cm^3。对8172个可观测反射精修所有的结构参数,最后偏离因子R=0.0781。此双冠醚以反-反式构型与Rb^+离子形成4:2(冠醚单元:阳离子)分子间夹心结构配合物,Rb_1和Rb_2分别与两个双冠醚分子中不同取向的醚环的十个氧原子配位。Rb-O平均键长为2.986和2.998(?),并与席夫碱型双冠醚苦味酸钾配合物进行比较。

The crystal structure of the complex prepared from the rigid Schiff base type bis (benzo-15-crown-5) bridged by w-phenylene with rubidium picrate was determined by X-ray crystallographic analysis. It was found that intermolecular 4 : 2 (crown ether unit : metal) sandwich type complex was formed between bis crown ether and rubidium ion instead of the intramolecular sandwich complex. The crystal is monoclinic, belongs to P21/n space group with α= 19.3049(49)A ,b = 20.4544(39)A,c=25.4375(75)A,β = 107.925(21)° .V=9556.90A3, F(000) = 4175.41 (e).All the structure parameter were refined with the 8172 observable refractions to give a final R = 0.0781. m-phenylene bridge between two crown ether units still maintained approximately the plane rigid form. The two benzo crown ether rings are situated at trans-trans position to the m-phenylene bridge and have different space orientations, Rb1 and Rb2 were coordinated with ten oxygen atoms within the ether ring having different space orientations in two bis crown ethers. The average Rb-O lengths are more longer than K-O lengths, but the angles On-Rb-On+1 are smaller than the angles of On-K-On+1. This indicates that the cavity formed by the two crown ether rings in the rubidium complex are more larger than the complex of potassium. The picrate anions interact with the larger cation by ionic bond.