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Calix[4]arenes are versatile ligands capable of forming a wide range of cluster motifs when reacted with 3d, 4for 3d/4fmetal ions. Synthetic modification at the calix[4]arene methylene bridge offers a unique opportunity to explore cluster formation with these alternative building blocks. Here, we present the synthesis of a range of bis-calix[4]arenes that are tethered by alkyl chains, as well as exploratory structural studies into cluster-forming reactions. Single crystals were formed in four cases, and from the X-ray structures elucidated it is possible to conclude that sufficiently long alkyl tethers allow for the formation of established cluster topologies without disruption to the core coordination chemistry. Synthetic modification at the calix[4]arene methylene bridge offers a unique opportunity to synthesise alternative supramolecular building blocks. This paper describes the synthesis of a range of alkyl-tethered bis-calix[4]arenes, as well as exploratory structural studies into polymetallic cluster formation. [ABSTRACT FROM AUTHOR]

The life and career of polymath and polyglot Christian Klixbüll Jørgensen, who contributed to inorganic chemistry, coordination chemistry, physical chemistry and spectroscopy over a period of more than four decades, are briefly discussed. [ABSTRACT FROM AUTHOR]

The reaction between the binuclear cobalt complex, [Co2(Et2dtc)5]+, and Me2pipdt and Ph2pipdt ligands has provided almost quantitatively the cobalt tris-chelate heteroleptic complexes [Co(Et2dtc)2(R2pipdt)]BF4 (1 and 2). The molecular structure of 2 shows the metal in a distorted octahedral geometry. The nature of the bonding in these complexes has been elucidated with the support of DFT TD-DFT calculations. Both chelating S,S donors work as weak-field ligands. The comparison of the chemical reactivity for the homoleptic dithiocarbamate complex [Co(Et2dtc)3] and the heteroleptic [Co(Et2dtc)2(Ph2pipdt)]+ derivative shows that the global softness σ is significantly higher in [Co(Et2dtc)2(Ph2pipdt)]+ than in the homoleptic dithiocarbamate complex, due to a reduction of nephelauxetic effect induced by the dithioxamide ligand. The kinetics for the reaction between the reagents in CH2Cl2 has been followed spectrophotometrically as a function of temperature in pseudo-first order conditions with respect to R2pipdt ligands. Kinetic results further support a reaction mechanism involving a one-end reversible dissociation of the [Co2(Et2dtc)5]+ dimer forming a reactive cobalt(III)dithiocarbamato center susceptible to attack by nucleophiles. The effectiveness and versatility of the above reaction is an easy and clean method to provide heteroleptic-dithiocarbamates with a variety of suitable ligands of interest for applicative purposes. [ABSTRACT FROM AUTHOR]

The life and career of Fred Basolo (1920-2007), dean of American coordination chemistry, 1983 President of the American Chemical Society, and contributor to inorganic chemistry, coordination chemistry, physical chemistry, and chemical education over a span of more than half a century, are discussed in this obituary-tribute. [ABSTRACT FROM AUTHOR]

The extraction of ruthenium by tri-n-butyl phosphate (TBP) is an issue for the PUREX process. The addition of 50 mM of 2,2ʹ-bipyridine (BIPY) reveals that ruthenium can be maintained in 3 M HNO3 aqueous solution after heating at 90°C for 4 hours. The Ru-BIPY complex was characterized using UV-Visible and Raman spectroscopies, and single crystal X-Ray diffraction. These technics are in agreement with a 1:2 complex formation in HNO3 medium. The selectivity toward uranium was studied by solvent extraction experiments: the BIPY ligand is still able to maintain ruthenium in the aqueous phase whereas uranium is still extracted. [ABSTRACT FROM AUTHOR]

A fresh look back at the chemistry of Bi3+ spanning solid state structural studies, aqueous biphasic separations, and a chromatographic purification of 213 Bi in support of its clinical use in targeted radiotherapy reveals the foundational importance of coordination chemistry and understanding the preferences exhibited by both the metal center and the ligand(s). Select structural studies of the nitrate and halide salts of Bi3+ complexes with the cyclic crown ethers and acyclic polyethylene glycols (PEGs) are reviewed, and the structure of [BiCl3(cis-anti-cis-dicyclohexano-18-crown-6)] is reported and compared to related structures. Liquid/liquid distribution studies emphasizing Bi3+ partitioning in PEG-based aqueous biphasic systems are presented and show that the distribution ratios using halide anions as extractants increase in the expected order: F- < Cl- < Br- < I-. Building on an understanding of the Bi-directed coordination chemistry in halide containing systems, the rationale for a chromatographic purification of 213 Bi is discussed, as are the performance data showing a 96% recovery of chemically and radionuclidically pure 213 Bi in just 0.25 mL of a strip solution that is directly compatible with binding to carboxylate-based biolocalization agents. The importance of coordination chemistry and an interdisciplinary scientific approach are highlighted, as are select future opportunities in targeted radiotherapy. [ABSTRACT FROM AUTHOR]

Two multi-component crystal structures comprising a carboxylic acid-functionalized imidazolium zwitterion, a p-sulfonatocalix[4]arene anion and aquated metal ion (Na+ or Y3+) with or without an auxiliary component (the 3-methoxyphenyl-triphenylphosphonium cation) are reported. The carboxylic acid-functionalized imidazolium ion binds either as a monodentate or a bidentate ligand depending on the nature of the metal ions, and a bi-layer arrangement prevails in the extended structure regardless of the type of metal ion employed or presence/lack of auxiliary component. [ABSTRACT FROM AUTHOR]

The coordination behavior of the tridentate alkoxy ligand 6,6'-(((2-hydroxyethyl)azanediyl)bis(methylene)) bis(2,4-di-tert-butylphenol) (termed H3-AM-DBP2) with group 4 metal alkoxides ([M(OR)4]) in a 1:1 ratio was previously found to generate [(ONep)Ti(κ 4 (O,O',O",N)-AM-DBP2)] and [(OR)Zr(κ4 (μ-O,O',O",N)-AM-DBP2)]2 (M = Zr, Hf). Additional studies revealed that increasing the stoichiometric ratio to 1:2 H3-AM-DBP2:[M(OR)4] led to the isolation of [(ONep)Ti(κ4 (μ-O,O',O",N)-AM-DBP2)(μ-ONep)Ti(ONep)3] (1)•tol, [(OBu t)Zr(κ4 (μ-O,O',O",N)-AM-DBP2)(μ-OBu t)Zr(OBu t)3] (2) and [(OBu t)Hf(κ4 (μ-O,O',O",N)-AM-DBP2)(μ-OBu t)Hf(OBu t)3] (3). The asymmetric dinuclear complexes of 1-3 resemble the chelation of a [M(OR)4] moiety to a "(OR)M(κ4 (O,O',O",N)-AM-DBP2)" fragment. The metal complexed by the AM-DBP2 ligand has a pseudo octahedral geometry while the other metal adopts an intermediate trigonal bipyramidal (TBP-5)/square base pyramidal (SBP-5) geometry for 1 but a distorted SBP-5 for both 2 and 3. The structure and properties of 1-3 were analyzed by computational modeling and fully characterized by standard analytical methods. [ABSTRACT FROM AUTHOR]

Calix[4]arenes are extremely versatile ligands that are capable of supporting the formation of a wide variety of polymetallic clusters of paramagnetic metal ions. One can exert influence over cluster formation through alteration of the calix[4]arene framework and subsequent ‘expansion’ of the lower-rim polyphenolic binding site. The present contribution investigates cluster formation with calix[4]arenes substituted at all four methylene bridge positions with furan moieties. Two known cluster types have been isolated with this ligand, the structures of which lend insight into factors that may ultimately preclude the formation of mixed-metal species. [ABSTRACT FROM AUTHOR]

The complex [NbOF3(Ipr)]2,1, was afforded in crystalline form by reaction of NbF5with the bulky NHC ligand 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) in toluene by slow contact with moisture air. The molecular structure of1was ascertained by X-ray diffraction, providing the first example of a dinuclear NbOF3derivative and also a rare case of niobium compound with a monodentate NHC. A DFT investigation has shown that the Nb–C bond consists of a weak NHC to Nbσdonation, reinforced by an electrostatic contribution presumably favored by the presence of the ancillary fluoride ligands. The computed enthalpy for the dissociation of one Ipr from1isca.36 kcal mol−1. The presence of bulky 2,6-diisopropylphenyl substituents on the carbene ligand has negligible influence on the Nb–C bond, as highlighted by DFT analyses on simplified models. [ABSTRACT FROM AUTHOR]

The reaction of copper(II) perchlorate with the hydrochloride salt of 3,6,9,15-tetra-azabicyclo[9.3.1]penta-deca-1,11,13-triene (L1) in acetonitrile forms two macrocyclic complexes that can be characterized: [L1CuIICl][ClO4] (1) and [L1CuIICl]2[CuCl4] (2). The structural, electronic, and redox properties of these complexes were studied using spectroscopy (EPR and UV–visible) and electrochemistry. In addition, the solid-state structure of1was obtained using X-ray diffraction. The copper(II) is five-coordinate ligated by four N-atoms of the macrocycle and a chloride atom. EPR studies of1both in DMF and aqueous solution indicate the presence of a single copper(II) species. In contrast, EPR studies of2performed in frozen DMF and in the solid-state reveal the presence of two spectroscopically distinct copper(II) complexes assigned as [L1CuIICl]+and [CuIICl4]2−. Lastly, electrochemical studies demonstrate that both [L1CuIICl]+and [CuIICl4]2−are redox active. Specifically, the [L1CuIICl]+undergoes a quasi-reversible Cu(II)/(I) redox reaction in the absence of excess chloride. In the presence of chloride, however, the chemical irreversibility of this couple becomes evident at concentrations of chloride that exceed 50 mM. As a result, the presence of chloride from the chemical equilibrium of this latter species impedes the reversibility of the reduction of [L1CuIICl]+to [L1CuICl]0. [ABSTRACT FROM AUTHOR]

There have been some notable developments in several areas of inorganic pharmaceuticals that have potentially far-reaching importance for future medical applications and research. One significant development in the field of oncology and hematology is the application of copper complexes. Copper ions play an important role in biological systems, and without their catalytic presence in trace or ultra trace amounts many essential co-factors for biochemical reactions would not take place. Copper is an essential component of several endogenous antioxidant enzymes. Copper affects the transcription of multiple defense and repair genes to protect against metal-induced pathologies. Copper creates stable complexes with a wide variety of organic molecules that can provide required biological affinity and therapeutical activity suitable for targeting specific locations in the body (when using radioactive copper isotopes,60Cu,61Cu,62Cu,64Cu,67Cu), as well as non-radioactive copper. The aim of this review is a critical evaluation of copper complexes used for therapy or diagnosis of various diseases in oncology from 2000 to the present. [ABSTRACT FROM AUTHOR]

A series of β-diketone hydrazone derivatives has been synthesized through condensation of β-diketone with aromatic aldehydes followed by reaction with phenylhydrazine. The structures of the ligands and intermediates are well defined through elemental and spectroscopic analyses. These hydrazones are potential ligands toward lanthanide metal ions. New complexes of trivalent scandium, yttrium, lanthanum, and cerium have been synthesized. The composition of these complexes is discussed on the basis of elemental analyses, infrared (IR) spectroscopy, magnetic moments and thermal analyses. The ligands are supposed to be bidentate with the two-sp2 nitrogen atoms. The prepared (1:1) metal:ligand complexes were screened for antibacterial and antifungal properties and have exhibited potential activity. Scandium(III) complexes are more active toward bacterium, yeast, and fungi. [ABSTRACT FROM AUTHOR]

Reactions of 2-, 3- and 4-aminobenzoic acids with alkaline earth metals in the presence of 1,10-phenanthroline (phen) have been investigated. Compounds [Ca(2-aba)2(phen)2(OH2)2] (1), [Ca(3-aba)2(phen)(OH2)3](phen)(H2O) (2) and [Ca(4-aba)(phen) (OH2)4](4-aba)(phen) (3) were synthesized from the corresponding metal precursors and 1,10-phenanthroline. The synthesis of [Sr(2-aba)2(phen)2(OH2)2] (4), [Sr(3-aba)2(phen)2(OH2)] (5), [Sr (4-aba)(phen)(OH2)4](4-aba)(phen) (6), [Ba(2-aba)2(phen)2(OH2)2], (7), [Ba(3-aba)2(phen)2(OH2)4] (8), and [Ba(4-aba)(phen)2(OH2)3] (4-aba)(H2O) (9) were accomplished from corresponding metal carbonates and aminobenzoic acids. The single crystal X-ray diffraction studies show that the complexes exist as discrete monomeric units held together by hydrogen bonding. The 2-aminobenzoate complexes 1, 4, and 7 are found to be isostructural where the metal ions are eight coordinated. The 4-aminobenzoate complexes 3, 6, and 9 exist as ion pairs. Carboxylate ligand prefers to bind the metal in a monodentate mode in most of these complexes. The molecules interact in the solid state via nonbonding interactions like hydrogen bonds and π-π stacking. [ABSTRACT FROM AUTHOR]

Reddish-orange single crystals of hexaamminecobalt(III) chloride selenate trihydrate, [Co(NH 3 ) 6 ]ClSeO 4 · 3H 2 O, have been prepared by reacting aqueous solutions of hexaamminecobalt(III) chloride and potassium selenate in a 1 : 1 molar ratio. The salt was characterized by elemental analyses, thermogravimetry, magnetic moment and spectroscopic studies (IR, electronic). A single crystal X-ray structure determination revealed that the title complex salt crystallizes in the orthorhombic space group Pnma with a = 18.230(2), b = 8.591(2), c = 8.593(2) Å, V = 1345.9(4) Å 3 , Z = 4, R = 0.0400 and R w = 0.0980. In the salt the network of hydrogen bonds between the hexaamminecobalt(III) cation, water molecule, chloride and oxygen atoms of the selenate ion represents the second sphere coordination and also suggests that [Co(NH 3 ) 6 ] 3+ may be used as an anion receptor for the selenate ion. [ABSTRACT FROM AUTHOR]

The structural and tautomeric peculiarities, as well as physical/chemical properties of transition metal complexes with o -quinones are reviewed. Synthetic routes for obtaining these complexes starting from different sources (elemental metals, metal carbonyls, salts, and metal complexes) are described and tabulated. The free-radical properties of metal- o -quinone complexes are discussed. [ABSTRACT FROM AUTHOR]