New Coordination Polymers Based On Transition Metal Squarates And Pyrazine Ligands

2003 ◽  
Vol 58 (1) ◽  
pp. 52-58 ◽  
Author(s):  
Christian Näther ◽  
Jan Greve ◽  
Inke Jeß
Keyword(s):  
Hydrogen Bonding ◽  
Transition Metal ◽  
Coordination Polymers ◽  
Hydrothermal Reaction ◽  
Squaric Acid ◽  
Water Molecules ◽  
Complex Behaviour ◽  
Metal Atoms ◽  
Linear Chains ◽  
Distorted Octahedra

Abstract Three new coordination polymers have been prepared by hydrothermal reaction of squaric acid, pyrazine and the metal halides FeCl2 · 4H2O, CoBr2 and NiBr2. In their crystal structures the metal atoms are coordinated by four water molecules and two pyrazine ligands within slightly distorted octahedra. The pyrazine ligands connect the metal atoms via μ-N,N’-coordination to linear chains which are connected via hydrogen bonding. The squarate dianions are not coordinated to the metal atoms and are located between the chains. The thermal behaviour of all compounds was investigated using TG-DTA-MS measurements. A complex behaviour for all compounds is found and the decomposition temperatures increase from Fe to Ni. From these investigations there are no hints for the occurrence of stoichiometric intermediate compounds.

scholarly journals Synthesis, Structural Characterization and Ligand-Enhanced Photo-Induced Color-Changing Behavior of Two Hydrogen-Bonded Ho(III)-Squarate Supramolecular Compounds

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1369 ◽  
Author(s):  
Wang ◽  
Ke ◽  
Feng ◽  
Ho ◽  
Chang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Uv Light ◽  
Squaric Acid ◽  
Water Molecules ◽  
Light Illumination ◽  
Supramolecular Architecture ◽  
Bridging Ligands ◽  
Coordination Modes ◽  
Oxygen Atoms ◽  
Hydrogen Bonded

Two coordination polymers (CPs) with chemical formulas, [Ho2(C4O4)2(C2O4)(H2O)8]·4H2O (1) and [Ho(C4O4)1.5(H2O)3] (2), (C4O42− = dianion of squaric acid, C2O42− = oxalate), have been synthesized and their structures were determined by single-crystal X-ray diffractometer (XRD). In compound 1, the coordination environment of Ho(III) ion is eight-coordinate bonded to eight oxygen atoms from two squarate, one oxalate ligands and four water molecules. The squarates and oxalates both act as bridging ligands with 1,2-bis-monodentate and bis-chelating coordination modes, respectively, connecting the Ho(III) ions to form a one-dimensional (1D) ladder-like framework. Adjacent ladders are interlinked via O–HO hydrogen bonding interaction to form a hydrogen-bonded two-dimensional (2D) layered framework and then arranged orderly in an AAA manner to construct its three-dimensional (3D) supramolecular architecture. In compound 2, the coordination geometry of Ho(III) is square-antiprismatic eight coordinate bonded to eight oxygen atoms from five squarate ligands and three water molecules. The squarates act as bridging ligands with two coordination modes, 1,2,3-trismonodentate and 1,2-bis-monodentate, connecting the Ho(III) ions to form a 2D bi-layered framework. Adjacent 2D frameworks are then parallel stacked in an AAA manner to construct its 3D supramolecular architecture. Hydrogen bonding interactions between the squarate ligands and coordinated water molecules in 1 and 2 both play important roles on the construction of their 3D supramolecular assembly. Compounds 1 and 2 both show remarkable ligand-enhanced photo-induced color-changing behavior, with their pink crystals immediately turning to yellow crystals under UV light illumination.

Transition Metal Squarates, II On the Structure of Cubic (MC4O4·2H2O)3CH3COOH·H2O(M=Zn2+,Ni2+)[1]

1986 ◽  
Vol 41 (11) ◽  
pp. 1329-1332 ◽  
Author(s):  
Armin Weiss ◽  
Eugen Riegler ◽  
Christian Robl
Keyword(s):  
Hydrogen Bonding ◽  
Transition Metal ◽  
Metal Ions ◽  
Water Molecules ◽  
Framework Structure ◽  
Space Group ◽  
3 Dimensional ◽  
Monodentate Ligands ◽  
Oxygen Atoms

Abstract The isotypic compounds (MC4O4·2 H2O)3·CH3COOH·H2O(M=Zn2+,Ni2+) crystallize in the cubic space group Pn3n. The 3-dimensional framework structure contains cavities, which may be filled with CH3COOH · H2O . The metal ions are coordinated almost octahedrally by two water molecules and four oxygen atoms of four C4O42- dianions. Thus the squarate dianions act as fourfold monodentate ligands. Strong hydrogen bonding between H2O and C4O42- has to be assumed.

Coordination polymers built from metal tripyrrin units

2008 ◽  
Vol 12 (12) ◽  
pp. 1242-1249 ◽  
Author(s):  
Martin Bröring
Keyword(s):  
Hydrogen Bonding ◽  
Coordination Chemistry ◽  
Transition Metal ◽  
Metal Ions ◽  
Coordination Polymers ◽  
Transition Metal Ions ◽  
Bridging Ligands ◽  
Secondary Interactions ◽  
Coordination Bonds ◽  
Linear Coordination

This account summarizes recent advances in the coordination chemistry of tripyrrins and related ligands with a special emphasis on the structural chemistry of coordination polymers with such ligands. The tripyrrin ligand is unique in supporting the formation of 1D- and 3D-supramolecular structures from pentacoordinate transition metal ions due to an effective blockage of their sixth coordination site. Linear coordination polymers have been observed with a multitude of bidentate and tridentate bridging ligands like trifluoroacetate, azide, thio- and selenocyanate, and higher order pseudohalides. Homo- and heterodimetallic species have been obtained by the use of cyanometallates and could be characterized structurally in two cases. Besides the covalent coordination bonds, several secondary interactions like hydrogen bonding and π-stacking were found to support these coordination polymers and are demonstrated to allow the preparation of species with functionalized inner surfaces.

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