Two cadmium(II) fluorous coordination compounds tuned by different bipyridines

Abstract

Fluorine is the most electronegative element and can be used as an excellent hydrogen-bond acceptor. Fluorous coordination compounds exhibit several advantageous properties, such as enhanced high thermal and oxidative stability, low polarity, weak intermolecular interactions and a small surface tension compared to hydrocarbons. C-H...F-C interactions, although weak, play a significant role in regulating the arrangement of the organic molecules in the crystalline state and stabilizing the secondary structure. Two cadmium(II) fluorous coordination compounds formed from 2,2'-bipyridine, 4,4'-bipyridine and pentafluorobenzoate ligands, namely catena-poly[[aqua(2,2'-bipyridine-κN,N')(2,3,4,5,6-pentafluorobenzoato-κO)cadmium(II)]-μ-2,3,4,5,6-pentafluorobenzoato-κO:O'], [Cd(CFO)(CHN)(HO)], (1), and catena-poly[[diaquabis(2,3,4,5,6-pentafluorobenzoato-κO)cadmium(II)]-μ-4,4'-bipyridine-κN:N'], [Cd(CFO)(CHN)(HO)], (2), have been synthesized solvothermally and structurally characterized. Compound (1) shows a one-dimensional chain structure composed of Cd-O coordination bonds and is stabilized by π-π stacking and O-H...O hydrogen-bond interactions. Compound (2) displays a one-dimensional linear chain structure formed by Cd-N coordination interactions involving the 4,4'-bipyridine ligand. Adjacent one-dimensional chains are extended into two-dimensional sheets by O-H...O hydrogen bonds between the coordinated water molecules and adjacent carboxylate groups. Moreover, the chains are further linked by C-H...F-C interactions to afford a three-dimensional network. In both structures, hydrogen bonding involving the coordinated water molecules is a primary driving force in the formation of the supramolecular structures.

Molecular and Polymer Ln2M2 (Ln = Eu, Gd, Tb, Dy; M = Zn, Cd) Complexes with Pentafluorobenzoate Anions: The Role of Temperature and Stacking Effects in the Structure; Magnetic and Luminescent Properties

“…A similar bonding of mononuclear fragments accompanied by the mutual orientation of aromatic rings was previously observed for cadmium pentafluorobenzoate complexes [Cd(H 2 O)(bpy)(pfb) 2 ] n (where bpy-2,2 -bipyridine) [32], [Cd(phen)(pfb) 2 ] n [55], and [Eu 2 (H 2 O) 2 Cd(etpy)(pfb) 8 ] n (where etpy-3-ethinylpyridine) [28]. As we have already noted, we were unable to isolate the pure phase of molecular complex V or its analogs comprising other lanthanides.…”

“…A special role in the formation of complexes with anions of fluorinated carboxylic acids and aromatic N-donor ligands is played by π-π interactions between the aromatic fragments of heteroligans, which additionally stabilize the crystal structure [27][28][29]. Additionally, fluorinated carboxylic acids are involved in the formation of C-H...F and C...F, F...F contacts, which also affect the stability of the crystal packing of the complexes [5,[30][31][32]. These intra-and intermolecular interactions can positively affect the luminescent properties of the resulting complexes [33][34][35].…”

Influence of the Arene/Perfluoroarene Ratio on the Structure and Non-Covalent Interactions in Crystals of Cd(II), Cd(II)-Tb(III) and Cu(II) Compounds

“…One of the most common π-deficient ligands is the anion of pentafluorobenzoic acid. We have previously shown that non-covalent interactions of the π•••π type can contribute to the stabilization of coordination polymers at compositions typical for molecular complexes in the case of cadmium complexes with pentafluorobenzoic acid anions and chelating N-donor ligands [10][11][12][13]. In such structures, the aromatic π-saturated and π-unsaturated fragments that are oriented parallel to each other enter into π•••π interactions and form a stacked packing.…”