尿素-富马酸根-水分子为主体晶格的四乙基铵离子包合物的合成与晶体结构

合成一种新的尿素-阴离子复合主体晶格包合物,(C₂H₅)₄N⁺C₄H₂O₄^2-]1/2·CO(NH₂)₂·H₂O,并进行了X射线晶体结构分析.晶体为单斜晶系,C₂/_c(No.15)空间群,a=1.7909(5)nm,b=1.4431(4)nm,c=1.4443(3)nm,β=126.76(2)°,V=2.9905(13)nm³,Z=4,R₁=0.0647,_wR=0.0735.包合物中,两个尿素分子通过一对N-H…O氢键以通常的“肩并肩”方式连接起来,形成一个二聚体.这些二聚体沿c轴方向依次排列,每两个相邻二聚体间生成的氢键将它们连接成一个沿(001)方向延伸的锯齿形扭带.由c滑移面相关连的富马酸阴离子以水分子为桥,由O(W)-H…O氢键连成一条宽带,沿c轴方向延伸.这些富马酸根-水分子复合氢键宽带与尿素纽带交替平行排列,由此形成了一个平行于ac面的氢键层.四乙基铵离子层填充在b=1/4和b=3/4处的主体晶格的层间空隙处,构成“三明治”式夹层结构的包合物.

Synthesis and Crystal Structures of Tetraethyl Ammonium Inclusion Complex with Urea, Fumarate and Water Molecules as Anionic Host Lattice Building

A new inclusion complex, (C₂H₅)₄N⁺C₄H₂O₄^2-] _1/2·CO(NH₂) ₂·H₂O, has been prepared and characterized by X-ray crystallography. Crystal data: space group C₂/c(No.15), a=1.790 9(5) nm, b=1.443 1(4) nm, c=1.444 3(3) nm, β=126.76(2)°, V=2.990 5(13) nm³, Z=4, F(000)= 1 168, μ=0.09 mm^-1, R₁=0.064 7 for 2 088 observed Mo Kα data (|F|²≥2.0σ|F|²). In the crystal structure of the title compound, two urea molecules are linked by a pair of N-H...O hydrogen bonds in the usual shoulder-to-shoulder manner to generate a dimer. These hydrogen-bonded urea dimers are alternately linked by additional pairs of N-H...O hydrogen bonds to form an approximately planar ribbon oriented parallel to the c axis. Bridged alternately by donor O(W)-H...O hydrogen bonds from the water molecules, the fumarate anions form a zigzag wide ribbon running parallel to the c axis. The parallel, alternate arrangement of these two kinds of complementary ribbons facilitates cross-linkage by N-H...O hydrogen bonds to form a puckered anionic layer normal to b axis. The title complex features a sandwich-like structure in which the tetraethylammonium cations occupy the space between urea-fumarate-water layers.