Synthesis, structure and magnetic properties of cobalt(II) and copper(II) coordination polymers assembled by phthalate and 4-methylimidazole

Abstract

New coordination polymers [M(Pht)(4-MeIm) 2 (H 2 O)] n (M=Co (1), Cu (2); Pht 2À =dianion of o-phthalic acid; 4-MeIm=4-methylimidazole) have been synthesized and characterized by IR spectroscopy, X-ray crystallography, thermogravimetric analysis and magnetic measurements. The crystal structures of 1 and 2 are isostructural and consist of [M(4-MeIm) 2 (H 2 O)] building units linked in infinite 1D helical chains by 1,6-bridging phthalate ions which also act as chelating ligands through two O atoms from one carboxylate group in the case of 1. In complex 1, each Co(II) atom adopts a distorted octahedral N 2 O 4 geometry being coordinated by two N atoms from two 4-MeIm, three O atoms of two phthalate residues and one O atom of a water molecule, whereas the square-pyramidal N 2 O 3 coordination of the Cu(II) atom in 2 includes two N atoms of N-containing ligands, two O atoms of two carboxylate groups from different Pht, and a water molecule. An additional strong O-H?O hydrogen bond between a carboxylate group of the phthalate ligand and a coordinated water molecule join the 1D helical chains to form a 2D network in both compounds. The thermal dependences of the magnetic susceptibilities of the polymeric helical Co(II) chain compound 1 were simulated within the temperature range 20-300 K as a single ion case, whereas for the Cu(II) compound 2, the simulations between 25 and 300 K, were made for a linear chain using the Bonner-Fisher approximation. Modelling the experimental data of compound 1 with MAGPACK resulted in: g ¼ 2:6; |D|=62 cm À1. Calculations using the Bonner-Fisher approximation gave the following result for compound 2: g ¼ 2:18; J ¼ 20:4 cm À1 .

From Mono‐ and Dinuclear to Polynuclear Cobalt(II) and Cobalt(III) Coordination Compounds Based on o‐Phthalic Acid and 2,2'‐Bipyridine: Synthesis, Crystal Structures, and Properties

“…The former (2a) is isostructural with the analogous Zn complex [14] and also consists of a centrosymmetric dinuclear [(bpy) 2 [10][11][12][13][14][15] It should be noted that the coordinated carboxylate group of the Pht residue in 2a is almost coplanar with the aromatic ring − the dihedral angle between them is 10.2(1)°; for the second carboxyl group this angle is equal to 74.1(1)°. The two mononuclear structural units consisting of one metal ion, two bpy molecules, and one residue of o-phthalic acid are linked by a very short symmetric O···H···O hydrogen bond of 2.447(3) Å between the carboxylate oxygen atoms O(1) and O(1A) into a dimer.…”

“…The Co-O(3) and Co-O(4) bond lengths for the bidentate carboxylate group are similar [2.196(5) and 2.181(5) Å], and that is a rather surprising result in light of the 1,3-chelating function of the Pht ligand. [11,14,15] There is a principal difference in the dihedral angles between the planes of the coordinated carboxylate group and the aromatic ring in compounds 5 and 4. In the former, this angle is equal to 61.5°, whereas in the latter the coordinated carboxylate group lies almost in the plane of the aromatic ring (the dihedral angle is 8°).…”

“…The neighboring Co···Co distance is 5.546(1) Å, slightly shorter than the Zn···Zn distance in [Zn(Pht)(bpy)(H 2 O)] n (5.633 Å) [33] and much shorter than that in the helix of [Co(Pht)-(4-MeIm) 2 ] n [6.247(1) Å]. [15] The adjacent complexes within the chain are joined additionally through two O-H···O hydrogen bonds between the coordinated water molecule and carboxylate oxygen atoms O(2) and O(4) of 2.570(8) and 2.760(8) Å, respectively. The chains are held together by van der Waals interactions ( Figure 13).…”

“…[19] Recently, we have also described the synthesis and structural characterization of cobalt(ii) phthalate coordination polymers with derivatives of imidazole, for example 1-methylimidazole (1-MeIm), [3] 2-methylimidazole (2-MeIm), [12] and 4-methylimidazole (4-MeIm). [15] In this paper we report on the synthesis, characterization, and crystal structures of three types of new cobalt(ii) and cobalt(iii) compounds with o-phthalic acid and 2,2Ј-bipyridine (bpy), namely the mononuclear cobalt(iii) and cobalt(ii) complexes [Co(CO 3 (5).…”

Self-assembly of a 1D helical manganese coordination polymer and a tetranuclear lanthanum complex with 1,10-phenanthroline and 3,5-dinitrosalicylato dianion

“…The Mn atoms are joined together with bridging carboxylate groups of 3,5-dinitrosalicylic acid ligands forming left-and right-handed helical chains in 1D (single-stranded) with a 2 1 -helix ( Fig. 2) similar to [Co(Pht)(4-MeIm) 2 (H 2 O)] n (Pht = dianionofo-phthalicacid; 4-MeIm = 4-methylimidazole) [35] and Zn(l-S,S-S 2 CN(H)CO 2 Et)(l-O,S-S 2 CN(H)CO 2 Et) [36]. In (1), Mn atom exhibits five coordination while in the similar Co polymer the hexa coordination was found [30].…”