Coordination Polymers of Copper(II) and Zinc(II) with 1-ethyl-1H-imidazole Incorporating Maleato or Malonato and Study of their Spectroscopic and Thermal Properties
Néné Oumy Khairy Lo
Laboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal.
Waly Diallo *
Laboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal.
Aîssatou Aliou Gaye
Laboratoire de Chimie de Coordination Organique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal.
Dame Sèye
Laboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal.
Bocar Traoré
Laboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal.
Nikolay Tumanov
Département de Chimie, Université de Namur, Rue de Bruxelles 61 – B-5000 Namur, Belgique.
Johan Wouters
Département de Chimie, Université de Namur, Rue de Bruxelles 61 – B-5000 Namur, Belgique.
Mamadou Sidibé
Laboratoire de Chimie Minérale et Analytique, Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal.
*Author to whom correspondence should be addressed.
Abstract
Polymer carboxylates coordination complexes formulated as [Cu(malea)(1-Etim)2]n (1) and [Zn(malon)(1-Etim)2]n (2) (malea = maleato, malon = malonato and 1-Etim = 1-ethyl-1H-imidazole) were prepared from maleic acid and malonic acid in the presence of 2-ethylimidazole as co-ligand. The complexes were characterized by elemental analysis, UV-visible and FTIR spectroscopies, thermogravimetry analysis (TGA), differential scanning calorimetry (DSC) analysis and X-ray diffraction. Complex 1 crystallizes in the tetragonal system space group I41cd with a = 16.0188 (14) Å, c = 26.1287 (4) Å, V = 6704.67(13) Å3 and Z= 16 whereas 2 crystallizes in the monoclinic system space group P21/n with a = 7.2539(2) Å, b = 25.1372(7) Å, c = 9.0422(3) Å, b = 111.8405(8) °, V = 1530.43 (8) Å3 and Z= 4. In complex 1, the copper (II) is situated in a N2O3 site, and its coordination sphere is best described as strongly distorted square pyramidal. The Cu(II) ion is linked to two nitrogen atom from two 1-ethyl-1H-imidazole molecules and one oxygen atom from a maleate dianion. The coordination sphere is completed by two oxygen atoms from a maleate group of a neighboring complex molecule. In complex 2, the Zn(II) center is coordinated by two nitrogen atom from two 1-ethyl-1H-imidazole molecules and one oxygen atom from malonate dianion. The fourth position is occupied by an oxygen atom of a maleate unit of a neighboring complex molecule. The environment around Zn(II) is described as distorted tetrahedral geometry. For both complexes, adjacent polymers chains are linked together by numerous intermolecular hydrogen bonds C—H···O, leading to a 3D network structure. Thermogravimetric analysis of the complexes was carried out at 25–700 °C and showed that the complex 1 decomposes in the temperature range 138-438 °C while complex 2 decomposes between 118 and 415 °C.
Keywords: Maleic acid, malonic acid, imidazole, coordination polymer, copper (II), zinc (II), X-ray