The ring-substituted phenoxyacetic acid (2-benzoyl-5-methoxyphenoxy)acetic acid (HL) (3) and its complex adduct dimer (4) with sodium, [Na2(L)2(HL)2].2HL, have been synthesized and their structures determined by X-ray diffraction. The acid (3) does not have the usual cyclic hydrogen-bonded dimer association, but instead has three-centre intramolecular hydrogen bonding between the carboxyl proton and both the ether and keto oxygens [O---O, 2.602(3), 2.711(3) Ǻ respectively]. Each sodium in the centrosymmetric complex dimer (4) is seven-coordinate [Na-O, 2.313(5)-2.612(5) Ǻ], involving the 'inner' three oxygens of both a protonated and an ionic ligand molecule. In addition, one of these carboxyl oxygens forms a bridge to the inversion-related sodium, while the uncoordinated carboxyl oxygen is hydrogen-bonded to a protonated carboxy group [O---O, 2.464(8) Ǻ]. The molecules of the lattice acid have only one hydrogen-bonded association with the second uncoordinated carboxy group in the dimer [O---O, 2.513(7) Ǻ].
我们合成了环取代苯氧基乙酸(2-苯甲酰基-5-甲氧基苯氧基)乙酸(HL)(3)及其与钠的复合加合物二聚体(4)[Na2(L)2(HL)2].2HL,并通过 X 射线衍射测定了它们的结构。酸 (3) 并非通常的环状氢键二聚体,而是在羧基质子与醚氧原子和酮氧原子之间具有三中心分子内氢键[O--O,分别为 2.602(3)、2.711(3) Ǻ]。中心对称复合物二聚体 (4) 中的每个钠都有七个配位[Na-O,2.313(5)-2.612(5) Ǻ],涉及质子化配体分子和离子配体分子的 "内部 "三个氧原子。此外,其中一个羧基氧与反转相关的钠形成桥接,而未配位的羧基氧则与质子化的羧基形成氢键[O--O,2.464(8) Ǻ]。晶格酸分子只与二聚体中第二个未配位的羧基有一个氢键联系[O---O,2.513(7) Ǻ]。