Syntheses, structures and properties of silver(I) complexes constructed from nitrogenous aromatic heterocyclic carboxylic acids and N-donor ligands

Four new coordination complexes with silver(I) ions and nitrogenous aromatic heterocyclic carboxylic ligands, namely [AB(4)(Pac)(Phen)(4)]center dot 8H(2)O (1), {[AB(4)(Pztc)(bPe)(3)] center dot 5H(2)O}(n) (2), [Ag-4(Hmptc)(2)(4,4'-bPY)(3)] center dot 4.5H(2)O (3), and [Ag-2(H(2)mPtc)(2)(2,2'-bPY)(2)] (4) (H(4)Pztc = pyrazine-2,3,5,6-tetracarboxylic acid, H(3)mptc = 6-methyl2,3,5-pyridine-tricarboxylic acid, phen = 1,10-phenanthroline, bpe = trans-1,2-bis(4-pyridyl)ethylene, 4,4'bpy = 4,4'-bipyridine, 2,2'-bpy = 2,2'-bipyridine), have been synthesized by the self-assembly reactions and characterized by X-ray diffraction single crystal structure analysis, elemental analysis, IR, PXRD, fluorescence and thermal analysis. In I, four crystallographically independent silver(l) atoms are found to coordinate with only one pztc(4-) ligand. Complex 2 is a 2D grid structure. Complexes 3 and 4 are extended from OD to 2D or 1D by the Ag center dot center dot center dot O interactions. (C) 2014 Elsevier B.V. All rights reserved.

Syntheses, structures and properties of cobalt and manganese complexes based on pyridine-2,3,5,6-tetracarboxylic acid

Chi Wai Cheung, Hong-Ling Gao, Weijin Wang

Two new complexes based on pyridine-2,3,5,6-tetracarboxylic acid(H(4)pdtc) as ligand, {[Co-2(pdtc)(H2O)(4)]center dot H2O}(n) (1) and {Mn-2(pdtc)(H2O)(4)}(n) (2), have been obtained by hydrothermal syntheses and characterized by IR, elemental analysis, X-ray diffraction single crystal structure analysis, PXRD, thermal gravimetric analysis, and magnetic measurements. Complex 1 is 3D coordination polymer and complex 2 belongs to 2D grid structure by covalent bonds. In 1 and 2, the metal ions show antiferromagnetic interactions. (C) 2015 Elsevier B.V. All rights reserved.

Elsevier Science Bv2015

Biologically derived metal organic frameworks

Samantha Lynn Anderson, Kyriakos Stylianou

Metal organic frameworks (MOFs) are extended structures composed of a network of organic ligands and metal ions or clusters connected to each other via coordination bonds. The numerous choices of organic ligands and metal coordination geometries have led to the construction of porous MOFs with various compositions, network topologies, pore sizes and shapes and they possess high surface areas and low densities. The structures of MOFs can be tailor-tuned in such a way that any desired ligand or/and metal ion can be incorporated; this has given to researchers the advantage of designing MOFs for a targeted application. Within this review, we overview recent examples of a sub-class of MOFs namely biologically derived MOFs (bio-MOFs), made of multifunctional and commercially available biologically derived ligands (bio-ligands) such as: amino acids, peptides, nucleobases and saccharides and focus on their coordination chemistry with a variety of metals. Central to this review are four tables detailing the coordination modes of bio-ligands to metals, along with a visual representation of the bio-MOF that is subsequently formed. Through the detailed analysis of these structures, we highlight the structural impact of these ligands on the structure, and their contribution to the MOF properties and applications. Finally, we showcase the potential of bio-MOFs in several research areas such as CO2 capture, separation, catalysis, drug delivery and sensing. (C) 2017 Elsevier B.V. All rights reserved.

Elsevier2017

Structure, dynamics and catalytic activity of ruthenium(II)-arene phosphine complexes

This thesis encompasses work on the coordination chemistry and catalytic activity of half sandwich ruthenium(II)-arene phosphine complexes. The investigation of phosphine dissociation and association reactions of these complexes represents the unifying theme of this study and, in addition to providing fundamental insights into the coordination chemistry of these compounds, allowed structure-activity relationships to be made and assisted in the development of new synthetic procedures. The thesis is organised into three parts according to the type of phosphine ligand investigated. The dissociation characteristics and catalytic activity of bis-phosphine complexes are presented in Chapter 2. The former properties were established by kinetic studies of ligand exchange and gasphase fragmentation analysis by tandem mass spectrometry, and helped to rationalise trends in the observed catalytic activity for the hydrogenation of styrene to ethylbenzene. The more active complexes were also shown to be chemoselective catalysts for the hydrogenation of aldehydes in the presence of olefinic bonds. Mechanistic studies were carried out in order to rationalise the preferential hydrogenation of aldehydes, which is consequently suggested to proceed via an ionic outer-sphere mechanism. Chapter 3 describes investigations on the coordination chemistry of ruthenium(II)-arene complexes containing diphosphine ligands. Complexes containing κ1-coordinated diphosphine ligands, with or without triphenylphosphine as a co-ligand, were prepared or characterised as the corresponding borane adducts. Mechanistic studies, including determination of enthalpies, entropies and, in two cases, volumes of activation, for the chelation reactions of the isolated κ1-diphosphine complexes were undertaken. The coordination chemistry of a chiral diphosphine, (R)-BINAPO, was also investigated; the synthesis of complexes containing this ligand in a range of coordination modes was achieved. The final chapter concerns the reactivity and catalytic activity of ruthenium(II) complexes containing (PPh2CH2)3CMe (triphos). Investigations of the catalytic activity of ruthenium(II)-arene complexes containing the κ2-coordinated triphos ligand were carried out together with pertinent reactivity studies and comparisons to structural analogues, which helped rationalise the observed activities. The reactivity and catalytic chemistry of one of the structural analogues, a ruthenium(II)-acetate κ3-triphos complex, was also investigated in detail as it proved to be a highly active catalyst for the hydrogenation of 1-alkenes.

EPFL2007

Structure, dynamics and catalytic activity of ruthenium(II)-arene phosphine complexes

EPFL2007