A Chiral Three Dimensional Potassium(I)/Strontium(II)/Chromium(III) Oxalato-Bridged Coordination Polymer: Synthesis, Characterization and Thermal Analysis

A new compound of general formula {[(H2O)2K(μ-H2O)Sr]@[Cr(C2O4)3]}n (1) has been synthesized in water and characterized by elemental and thermal analyses, EDX, IR and UV-Vis spectroscopies and by single crystal X-ray structure determination. Compound 1 crystallizes in the chiral space group Fdd2 of orthorhombic system with a = 14.110 (4) ?, b = 36.074 (11)?, c =11.034 (3)? and Z = 16. Compound 1 is a coordination polymer in which the three-dimensional lattice framework is realized by the interconnectivity between K+ cations, Sr2+ cations, aqua ligands and [Cr(C2O4)3]3– complex anions. The asymmetric unit of 1 consists of one cationic motif formally written [(H2O)2K(μ-H2O)Sr]3+ and one anionic entity, [Cr(C2O4)3]3–. The K+ and Sr2+ ions in the cationic motif are both eight-coordinate while the Cr3+ ions in the anionic complex are six-coordinate in a distorted octahedral geometry. Coulombic interactions between the ionic motifs and the three-dimensional H-bonding involving aqua ligands help to consolidate the bulk structure. Thermogra-vimetric analysis (TGA) shows that compound 1 is stable to heat up to ca. 80℃.

Synthesis, Crystal Structure and Thermal Behavior of a 3-D Barium(II)/Iron(III)-Oxalate Polymer

Reaction of Ba(NO3)2 with Fe(NO3)3·9H2O and H2C2O4·2H2O in aqueous medium readily affords, in high yield, the bimetallic complex polymer of chemical composition {Ba6(H2O)17[Fe(C2O4)3]4}·7H2O (1), consistent with the expected ratio of 3BaII vs. 2FeIII. Compound 1 was fully characterized by elemental and thermal analyses, vibrational FTIR spectroscopy, and by single crystal X-ray structure determination. The bulk structure of 1 is a 3-D metal-organic framework held together by intermetallic linkages across oxalate and aqua oxygen bridgings. Thermal analyses of 1 show significant weight losses corresponding to water molecules (lattice and coordinated), followed by the decomposition of the network.

三草酸合铁(Ⅲ)酸钾合成方法的改进

三草酸合铁(Ⅲ)酸钾具有工业生产价值,其合成作为化学专业本科生的经典实验项目,按教材实验的效果却不尽人意。本文在严谨的化学平衡理论分析基础上,首次提出提高合成产率的关键是严格控制草酸和草酸钾的用量,改进后的合成条件为:氧化步骤H_2O_2的浓度为6%,水浴温度为40°C;充分氧化后,微沸2分钟;酸溶步骤中草酸稍微过量,草酸钾过量10%;结晶时做到充分冷却。经此改进,可简化操作,节约原料,实验室平均产率达87%,教学中学生实验平均产率超过70%。

三草酸合铁(Ⅲ)酸钾合成条件的改进与探索

针对无机化学综合实验三草酸合铁(Ⅲ)酸钾合成过程中存在的问题,对[K3Fe(C2O4)3].3H2O的合成条件进行探索和优化.实验结果表明:在用热水(40℃)洗涤FeC2O4,40℃时逐滴加入H2O2后煮沸30s,利用浓缩后挂棉线的方式进行结晶等条件下,得到粒度较大的翠绿色晶体,可改善实验结果的重现性、提高产品的产率和纯度.