Synthesis, Crystal Structure, and Spectroscopic Characterization of trans-Bis[(μ-1,3-bis(4-pyridyl)propane)(μ-(3-thiopheneacetate-O))(3-thiopheneacetate-O)]dicopper(II), {[Cu₂(O₂CCH₂C₄H₃S)₄μ-(BPP)₂]}_n:  From a Dinuclear Paddle-Wheel Copper(II) Unit to a 2-D Coordination Polymer Involving Monatomic Carboxylate Bridges

Abstract

From the reaction between a dinuclear paddle-wheel carboxylate, namely [Cu2mu-(O2CCH2C4H3S)4] (1), and the flexible ligand 1,3-bis(4-pyridyl)propane (BPP) a neutral 2-D coordination polymer [[Cu2(O2CCH2C4H3S)4mu-(BPP)2]]n (2) was obtained. Compounds 1 and 2 were characterized by means of elemental analysis, thermal analysis (TG/DSC), vibrational spectroscopy, and electron paramagnetic resonance (EPR). The crystal structure of 2 reveals that each Cu(II) is coordinated by two nitrogen atoms from different BPP ligands and two 3-thiopheneacetate groups within a distorted square planar geometry in a trans-[N, N, O, O] arrangement. The BPP ligand adopts a TG conformation bridging two copper centers giving rise to a 1-D sinusoidal polymeric chain along the crystallographic c axis. Adjacent 1-D chains are extended into a 2-D coordination network through pairs of monatomic carboxylate bridges in direction of the b axis. This bridging mode affords centrosymmetric dimeric units Cu2O2, and therefore, the copper ions are involved in a CuN2O2O' chromophore displaying a (4 + 1) square pyramidal coordination in the resultant 2-D polymeric network. The polycrystalline X-band EPR spectrum of 2 at room temperature is characteristic of a triplet state with nonnegligible zero-field splitting in agreement with the crystal structure. Crystal data for 2: monoclinic, space group P2(1)/c, a = 9.4253(10) A, b = 10.9373(10) A, c = 23.6378(10) A, beta = 98.733(4) degrees, Z = 2.

Chain Compounds Based on Paddle-wheel Copper(II) Carboxylate Bearing Four Nitroxide Radicals

“…The medium band at around 1009-1074 cm −1 can be assigned as the pyridine ring-breathing modes, suggesting the presence of the pyridine-containing linking ligands in the compounds 3-6 and 9-12 [30]. It is known that the shift of the pyridine ring vibrational band (ν (CC/CN)) to the higher energy side is indicative of the coordination of the pyridine nitrogen atom to metal ion [31][32][33]. The corresponding vibration of free 4,4 -bpy, bpe, bpel, and pds could be observed as a strong band at 1597, 1596, 1596, and 1574 cm −1 , respectively.…”

New Bioactive Heteroleptic Copper(II) Carboxylates: Structure, Enzymatic and DNA-Binding Studies

“…Each monomer in crystal lattice is linked to another monomer through hydrogen bonds which arises between uncoordinated O2 and O4 atoms of carboxylate moiety and hydrogen atoms of phenanthroline rings with distance of 2.57 Å. In addition to this, Cl atoms also participate in intermolecular hydrogen bonding with near- (7) 91.79(7) O1-Cu1-O1 i 76.52 (6) 77.68(7) N1-Cu1-O1 i 93.91 (7) 95.41(7) N2-Cu1-O1 i 113.54 (7) 102.99 (7) Symmetry codes: i = 2 -x, -y, -z for 1; i = -x, 2 -y, 1 -z for 2.…”

“…[1][2][3][4] A number of bioactive metal carboxylates have also been reported to date. 5,6 Inevitable relationship between chemical reactions naturally carried out within the human body, pharmacology and medicine has lead the scientists to design new bioactive materials in the form of potent drugs for therapeutic intervention in treatment of many life threatening diseases. Metal charge, interactions with ligands, structure and bonding, Lewis acid character, partially filled d-shell and its redox activity defines its suitability for biological systems.…”

Polynuclear paddle-wheel copper(II) propionate with di-2-pyridylamine or 1,10-phenanthroline: Preparation, characterization and X-ray structure

“…Dimeric and polynuclear copper(II) carboxylates have received great attention in the studies of exchangecoupling interactions between adjacent metal centers, as well as for their special bioactive and biocatalytic functions [1][2][3][4][5][6][7]. In addition, carboxylate anions exhibit a versatile coordination behavior displaying distinct bonding modes toward metal cations, such as monodentate and chelate, as well as g 1 :g 1 :l bridging ligands in syn,syn, syn,anti, and anti,anti conformations.…”

“…A large number of paddle-wheel type dimeric copper(II) carboxylate adducts, [Cu 2 (RCO 2 ) 4 L 2 ], where L is an apical ligand with an oxygen or a nitrogen atom, have been reported in an effect to clarify the factors influencing the magnitude of the intramolecular magnetic exchange interaction which occurs between two Cu(II) ions of a paddlewheel moiety in these compounds [1,[8][9][10]. The polynuclear copper(II) carboxylates were found to exhibit three classes of local paddle-wheel structure: (A) stepped polymeric structure with the second lone pair is donated to a metal ion of another paddle-wheel unit [8]; (B) stepped without additional ligands with polymeric structures can also be obtained by means of ligands which are able to bridge between dinuclear units [9]; (C) the bridging ligand coordinates axially to a Cu ion and at the same time interacts with a carboxylate oxygen atom of another paddle-wheel unit [10].…”