title: Symmetry breaking of α-[H2W12O40](6-) depends on the transformation of isopolyoxotungstates.
abstract: Two enantiotopic 1D chain compounds, [Cu3(L1)3(H2O)2(H2W12O40)]·4H2O (1a,b; L1 = 2-(4,6-bis(pyridin-2-yl)pyridin-2-yl)pyridine), crystallizing in the chiral space group P212121 were prepared and spontaneously resolved in the absence of any chiral source. Interestingly, compounds 1a,b can be prepared from a [W7O24](6-) aqueous solution, [(n-C4H9)4N]4[W10O32], or Na10[H2W12O42], but when [H2W12O40](6-) aqueous solution was the starting material, the achiral compound [CuL1]2[H4W12O40]·5H2O (2) was obtained. When a terpyridine ligand (L2) having a coordination mode similar to that of L1 was used, the mesomeric dimer [Cu3(L2)3(H2O)(H2W12O40)]2·4H2O (3) was obtained from [W7O24](6-) aqueous solution or Na10[H2W12O42], but from [H2W12O40](6-) aqueous solution only compound [Cu2(L2)2Cl2]2[W10O32] (4) was isolated. It is notable that in compounds 1a,b and 3 the symmetry of the α-[H2W12O40](6-) cluster is broken by asymmetric coordination with metal-organic units in a similar mode. As the asymmetric subunit based on a tridecorated [H2W12O40](6-) cluster can be obtained from several isopolyoxotungstate sources except for [H2W12O40](6-), we speculate that the symmetry breaking of α-[H2W12O40](6-) depends on the transformation of isopolyoxotungstates. Furthermore, during the transformation a possible reaction intermediate as the precursor for 1a,b, compound [Cu3(L1)3(H2O)3(H4W11O38)] (5), has been presented and characterized by density functional theory (DFT) calculations.
authors.affiliation: Key Laboratory of Cluster Science Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic, School of Chemistry, Beijing Institute of Technology Beijing 100081, People's Republic of China.
authors.forename: Ying-Nan
authors.initials: YN
authors.lastname: Chi
authors.forename: Pan-Pan
authors.initials: PP
authors.lastname: Shen
authors.forename: Feng-Yun
authors.initials: FY
authors.lastname: Cui
authors.forename: Zheng-Guo
authors.initials: ZG
authors.lastname: Lin
authors.forename: Shi-Lu
authors.initials: SL
authors.lastname: Chen
authors.forename: Chang-Wen
authors.initials: CW
authors.lastname: Hu
mesh_terms: D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D017973:Tungsten Compounds / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D017973:Tungsten Compounds; D003300:Copper