【摘要】 以具有支链结构的溴代仲丁烷作为烷基化试剂,在微波辐射下采用两步法合成了1-仲丁基-3-甲基咪唑六氟磷酸盐([s-bmim][PF6])离子液体.在配比为V(水)∶V(乙醇)∶V(甲苯)=0.16∶2.84∶7的混合溶剂体系中,培养出晶型完整的长约11mm的离子液体大单晶体.通过单晶体X衍射研究了[s-bmim][PF6]的晶体结构.[s-bmim][PF6]属于三斜立方晶系,空间群为P2(1)/m,晶胞参数为a=0.9042(4)nm,b=0.8213(3)nm,c=0.9775(4)nm,γ=116.618°(6),Z=2,V=64.909(4)nm3,Dc=1.454g/cm3,μ=0.265mm-1,F(000)=292.在[s-bmim][PF6]晶体结构中,阴阳离子间的离子键仍然是主要的,同时还存在氢键和阳离子-阳离子间的非键斥力作用.研究结果表明,[s-bmim][PF6]的支化烷基结构对其晶体有效堆积、熔点、液程范围以及热分解温度等性质具有重要影响.更多还原

【Abstract】 In this paper,1-sec-butyl-3-methylimidazolium hexfluorophosphate([s-bmim][PF6])was synthesized with the aid of microwave.Large single crystals were formed in the water-ethanol-toluene system[V(water)∶V(ethanol)∶V(toluene)=0.16 ∶2.84 ∶7].The large single crystals are stable under the air and moisture,with the maximum length of 11 mm.The crystal structure was determined by X-ray diffraction.[s-bmim][PF6] crystallizes in the monoclinic space group P21/m,with unit-cell parameters a=0.9042(4)nm,b=0.8213(3)nm,c=0.9775(4)nm,γ=116.618°(6),Z=2,V=64.909(4)nm3,Dc=1.454 g/cm3,μ=0.265 mm-1,F(000)=292,the final R=0.0998,wR=0.2656.In the structure,the cations and anions can not form neutral ion pairs owing to the interionic interactions such as the dominant Coulombic attraction,the weak hydrogen bonds and the non-chemical-bond tension of cation-cation.Moreover,it was found that introducing the sec-butyl chain could change the asymmetry of cations and inhibit the rotation of the alky chains of [s-bmim][PF6].The branched structure leads to the void space filling in the crystal stacking and high lattice energy.Finally,the thermal stability of [s-bmim][PF6] was discussed.更多还原