Structural and spectroscopic studies of three novel two- and three-dimensional coordination polymers with benzenetricarboxylate ligands

Abstract The synthesis, crystalline structure and vibrational characterisation of three new complexes with benzenetricarboxylate ligands are described in this work. Compound 1 {Na 5 [Cu 3 (C 9 H 3 O 6 ) 3 (C 9 H 4 O 6 )(H 2 O) 10 )]·(H 2 O) 3 } was synthesised from 1,2,3-benzenetricarboxylic acid. This complex crystallised in a triclinic non-centrosymmetric space group (P1), and a three-dimensional coordination polymer was formed. This polymer displays an 8-connected uninodal net with the short Schlafli symbols (4 24 6 4 ). Conversely, compounds 2 {[CoK 2 (C 9 H 4 O 6 ) 2 (H 2 O) 6 ]} and 3 {[Zn 2 (C 9 H 4 O 6 ) 2 (H 2 O) 6 ]} were synthesised from 1,2,4-benzenetricarboxylic (4-btc). These complexes crystallised in the triclinic centrosymmetric group P 1 ¯ , and, in both cases, two-dimensional coordination polymers were observed by X-ray diffraction. Compound 2 forms a 6,7-connected binodal net with the short Schlafli symbols (3 9 4 9 5 3 ) 2 (3 6 4 2 5 6 6). A 4,6-connected binodal net is also observed for compound 3 , and it presents Schlafli symbols equal to (3 2 4 2 5 2 )(3 4 4 4 5 4 6 3 ). In the infrared spectra, characteristic bands were observed at 1615 and 1459 cm −1 for 1 , at 1615 and 1264 cm −1 for 2 and at 1592 and 1260 cm −1 for 3 arising from the anti-symmetric and symmetric stretching modes of the carboxyl group (COO − ), respectively. The difference between these frequencies suggests that the metal coordination mode in the complexes is monodentate, which agrees well with the X-ray diffraction data.