Crystal structure of bis(μ2-4-carboxy-2-sulfonatobenzoato)- bis[aqua(2,2′-bipyridyl)copper(II)] hexahydrate, [Cu(H2O)(C10H8N2)(C8H4O7S)]2 · 6H2O

Abstract

Source of materialAmixture of STP (2-sulfoterephthalic acid, 0.025 g, 0.1 mmol), CuCl 2 (0.013 g, 0.1 mmol), 2,2'-bipy (0.016 g, 0.1 mmol), and H 2 O(10 ml) was stirred for about 30 min. The resulting solution was sealed in aTeflon-lined stainless autoclave and heated to 393 Kfor 3days. The bottle was cooled to ambient temperature spontaneously. Blue block-like single crystals (about 90 %, based on Cu) were recovered by vacuum filtration and drying in air. Elemental analysis -f ound: C, 32.76 %; H, 4.16 %; N, 5.83 %; calulated for C 36H40Cu2N4O22S2:C,32.84 %; H, 4.24 %; N, 5.90 %. Experimental detailsThe C-bound Ha toms were geometrically placed (d(C-H) = 0.93 Å)and refined as riding with U iso(H) =1.2 Ueq(C). The Obound Ha toms were located in difference maps and refined as riding with U iso (H) =1.2U eq (O). DiscussionTerephthalate is an important rigid multicaboxylate ligand for construction of extended coordination solids owing to its high symmetry and coordination ability for abroad range of metal ions [1][2][3][4][5]. Introduction of asulfonate group into rigid multicarboxlate ligands may result in the formation of unexpected frameworks as the sulfonic group has adifferent shape and properties in terms of its coordination ability compared to the carboxylate group. Since apseudo-honeycomb coordination polymer constructed by copper(II) and the 5-sulfo-isophthalic acid as ligand was firstly reported [6], the studies of this ligand have received considerable attention [7][8][9][10][11][12][13][14][15]. However, the studies of the 2-sulfoterephthalic acid (H 3 STP) are not very common [16][17][18][19]. The asymmetric unit in the title structure contains one copper ion, one 2,2'-bipyridine molecule, one deprotonated HSTP 2-anion and four water molecules. The copper center is surrounded with two pyridine Na toms of a2 ,2'-bipyridine molecule, one carboxylate Oa tom, one water molecule, and one sulfonate O atom. One carboxylate Oatom, one coordinated water molecule and two 2,2'-bipyridine Na toms form the basal plane, and the sulfonate Oatom occupies the apical site. The copper coordination is thus the square pyramidal one. The Cu-N and Cu-Obasal bond lengths range from 1.9538(2) -1.993(2) Å,which is consistent with those found in comparable structures [7,14]. The Cu-O sulfonate bond distance is much longer than that of Cu-O carboxylate which is the most frequent with copper sulfonates. The C-O distances are consistent with the location of the Hatoms deduced from difference maps, which indicate that the HSTP ligand carries ac harge of -2f or charge balance. The HSTP 2-anion coordinates to the symmetry-related copper ions through its sulfonate Oatom and carboxylate Oatom. The whole HSTP 2-ligand links metal centres in a m 2 mode to generate a dimeric unit forming short bridges, which define a14-membered ring. As found in the previous complex [16], the dihedral angle between aromatic ring and the plane of the carboxylate group is 78.54°, which is made possible by the well matched ionic size. The terminal COOH group ...