Structrures And Characterization Of Rare Earth Metal-SIP Coordination Polymers (SIP=5-Sulfoisophthalic Acid)

In coordination chemistry,the coordination ability of sulfonic groups is relatively weak compared with carboxyl groups in organic ligands. Sulfonic group have three oxygen atoms, so it made these ligands have so much more varities of coordination style. If other proper groups are introduced into these ligands, more coordination compounds with novel structure can be obtained. And the coordination ability of carboxyl groups is very strong, when they are combined in ligands with sulfonic groups, the ability of them would be improved greatly. So we studied the reaction of 5-sulfoisophthalic acid monosodium salt and Rare Earth Metal in this paper, mainly studying synthesis method of coordination which have different structures.We had synthexized six compounds and made some characterizations through crystal X-ray diffraction, X-ray powder diffraction, IR and thermogravimetric analysis,and investigate that coordination compounds were influenced by different reaction conditions[La(SIP)?(H2O)4]n [1] and [Ce(SIP)(H2O)4]n [2] were obtained respectively by mixing the 5-sulfoisophthalic acid monosodium salt with La(NO3)?6H2O hydrothermal condition and with Ce(NO3)3?6H2O at normal temperature, respectively. In structure of compound [1] , center metal ions La (Ⅲ) show nine-coordination feature; Every La (Ⅲ) was surrounded by three SIP, including two oxygens of two carboxyl groups which coordinate with metal ion by chelating and one sulfonic oxygen atom by bridging in these structures. Meanwhile, the La (Ⅲ) atoms coordinate with four oxygens atoms which offer by four water molecules. And every SIP coordinated with three La (Ⅲ) ions through its two carboxylic groups and the sulfo group. Compound [2] is a reported compound.{[Ce(SIP)(H2O)3]?(H2O)}n [3] and {[La(SIP)(H2O)3]?H2O}n [4] were obtained by mixing the 5-sulfoisophthalic acid monosodium salt with La(NO3)?6H2O in hydro-thermal condition and with Ce(NO3)3?6H2O at normal temperature, respectively. The structure of compound [3] is a asymmetric unit which contains one Ce (Ⅲ) ion, five SIP, three coordinating water molecules and one free water molecules. Center ions Ce (Ⅲ) coordinated with nine oxygen, including four carboxylic oxygen atoms (O1,O2, O6, O7) of three SIPs, two sulfo oxygen atoms (O4,O3A) of other two SIP molecules and another three oxygen atoms of three coordinated water molecules. Compound [4] was a reported complex.[Ce(SIP)?5H2O]n?3H2O [5] was obtained by mixing the 5-sulfoisophthalic acid monosodium salt with Ce(NO3)3? 6H2O directly. This compound is a asymmetric structure, which contains a Ce (Ⅲ), eight water molecules and one SIP. The Ce (Ⅲ) atoms show the property of nine-coordination, in which including four carboxylic oxygen atoms of two SIP connecting with metal atom by chelating and five oxygen atoms of five water molecules. Meanwhile there are another three free water molecules in the compound, and two carboxylic groups of one SIP connected the two Ce (Ⅲ). Metal ions Ce (Ⅲ) and SIP form an infinite long Zigzag chain, and a stable 2-D construction is formed due to the superimposition of benzene and strong effects ofπ-πstacking. In this complex, the sulfo group don't participate in coordination.[Cu(C5H3O4N)?2H2O] [6] was obtained by mixing the 2,6-Dipicolinic acid with CuCl2?2H2O and NaVO3?2H2O directly, but no vanadium compound was gained. In compound [6], Cu (Ⅱ) ions coordinate with other five atoms. This compound looks like a butterfly, in which two carboxylic oxygen atoms and one N atom of one 2,6-Dipicolinic acid coordinate with metal atom, and other two oxygen atoms of two water molecules also participate coordinating.Three compounds are new polymer and the three others are existing compounds among the six synthesized compounds.