Investigation of the Coordination Behavior of P4S3 towards CuBr

The formation of coordination polymers from copper(I) bromide and P₄S₃, a potentially tetradentate P‐donor bridging ligand, was studied. Whereas (P₄S₃)₃(CuBr)₇ ( 1 ) formed in excellent yield, (P₄S₃)(CuBr)₃ ( 2 ) and (P₄S₃)(CuBr) ( 3 ) crystallized as mixtures. The new compounds were characterized by X‐ray crystallography and solid‐state ³¹P MAS NMR spectroscopy. The structure of 1 consists of a 3D network of cylindrical (CuBr)_n columns, castellated (CuBr)_n chains and diatomic CuBr units. These building blocks are linked by tetradentate P₄S₃ molecules. The structure of 2 comprises undulated (CuBr)_n layers, which are intra‐ and interlayer linked by tridentate P₄S₃ molecules. Compound 3 is a one‐dimensional polymer composed of four‐membered Cu₂Br₂ rings, which are bridged by the P₃ bases of two P₄S₃ molecules.     

Sustainable and Selective Modern Methods of Noble Metal Recycling

Noble metals exhibit broad arrange of applications in industry and several aspects of human life which are becoming more and more prevalent in modern times. Due to their limited sources and constantly and consistently expanding demand, recycling of secondary and waste materials must accompany the traditional mineral extractions. This Minireview covers the most recent solvometallurgical developments in regeneration of Pd, Pt, Rh, Ru, Ir, Os, Ag and Au with emphasis on sustainability and selectivity. Processing—by selective oxidative dissolution, reductive precipitation, solvent extraction, co-precipitation, membrane transfer and trapping to solid media—of eligible multi-metal substrates for recycling from waste printed circuit boards to end-of-life automotive catalysts are discussed. Outlook for possible future direction for noble metal recycling is proposed with emphasis on sustainable approaches.     

Two Coordination Networks Built from p‐Sulfonatothiacalix[4]arene Tetranuclear Clusters

Two coordination compounds based on p‐sulfonatothiacalix[4]arene (TCAS) were synthesized by hydrothermal reactions of TCAS with M²⁺ cations (M = Cu for 1 , M = Co for 2 ) in the presence of [PhCH₂N(CH₃)₃]⁺. Single‐crystal X‐ray analyses revealed that both compounds, 1 and 2 , are isomorphous and crystallize in the same space group . The tetranuclear cluster units are connected into layer networks through complicated hydrogen‐bonding and π–π interactions. The results of thermogravimetric measurements demonstrate that 1 and 2 have the high thermal stabilities.     

Novel Cyanide Coordination Models in Layer-Type Hydrated Double Salts of AgCN and AgF

The edge-bridged triangular cluster [Ag₃(μ-CN)₃(H₂O)₃] (left in picture) and the pseudo-cubane moiety [Ag₃F(H₂O)₃] with an unoccupied Ag position (right in picture)—both hitherto unknown—are found in two new layer-type double salts of AgCN and AgF that display novel types of cyanide coordination modes.     

Phosphorylated Calixarenes in Design of Receptors for Metal Cations and Organic Molecules

A series of calix[4,6]arenes functionalized with phosphinoxyde, diphosphindioxyde, and carbamoylphosphinoxide groups, which possess high binding ability to metal cations or protodonative organic molecules and are linked to the wide rim of macrocyclic skeleton by different spacers, has been synthesized.     

Self-Assembly of Lamellar and Expanded Lamellar Coordination Networks

Structural similarity with clay-type minerals is apparent in the self-assembled layered coordination network [{Ag( 1 )(MeCN)₂}_∞][BF₄]_∞, which is stabilized by a lamellar chelate effect (section of structure shown on the right). The interlayer region is expandable through the use of larger ligands such as PhCN. The void space is occupied by one PhCN molecule per repeat unit.     

Metal Complexes of Sulfur Ylides: Coordination Chemsistry,Preparative Organic Chemistry,and Biochemistry

In recent years both acyclic and cyclic sulfur ylides have proved to be interesting and versatile ligands in preparative organometallic chemistry. In addition to paralleling the coordination chemistry of their phosphorus analogues, sulfur ylide complexes show specific structural and chemical features; they are becoming more important in preparative inorganic and organic chemistry, and may also be biochemically relevant as methylene transfer agents. Recent studies of the complexes of the ylidic λ⁴-thiabenzenes and λ⁶-thiabenzene 1-oxides have frequently demonstrated unexpected and novel reactions, and thereby enriched the chemistry both of ylides and of carbonylmetals.     

The Crystal Chemistry of Copper Oxometalates

Up to three or four years ago oxocuprates were a class of chemical compounds no more remarkable than countless others. Then, as a result of the euphoria surrounding the high-temperature oxide superconductors and the discovery that copper plays an essential role in these materials, there was a world-wide awakening of interest in copper-containing oxide compounds. The number of scientists engaged in the synthesis and structure determination of copper oxometalates has grown from just a few to very many. As superconductivity is inseparably connected with the structure of the solid state, there has been a spontaneous awakening of interest in the role of copper in the crystal chemistry of solid materials, leading to new research projects on this aspect of oxocuprates. Most of the work published so far on the interesting chemistry of this group of compounds has related to individual compounds. New aids in describing complex solid state structures are now available through the development of methods that give three-dimensional displays of crystal structures using computer graphics terminals, as this review illustrates for the example of the oxocuprates.     

The Coordination Chemistry of Multidentate Isocyanide Ligands

In spite of the excellent ligation properties of isocyanides, until a few years ago there was only a small number of known multidentate ligands of this type. One of the reasons for this lack of interest, when compared to monodentate isocyanides, was the linear arrangement of the M? C?N? R group, which usually inhibits the formation of mononuclear chelate complexes and leads to the formation of multinuclear or polymeric metal complexes. In these, the multidentate ligand acts in a monodentate fashion towards each metal atom. Only recently has a series of polyisocyanides with large ligand backbones been synthesized successfully. Bidentate isocyanides can bridge two metal atoms or react to give chelates with only one metal center. Tripodal ligands form mono- or binuclear complexes, in which the largest organometallic rings observed to date occur (up to 36 atoms). This class of ligands promises to be interesting for the synthesis of stable, diagnostically important technetium complexes of the type [Tc(CNR) ₆ ]⁺. There also appear to be applications for tripodal isocyanides in catalysis. A facial, chiral Cr(CNR^*)₃ unit might be able to catalyze the hydrogenation or isomerization of prochiral double bonds. It is even possible to bind triisocyanides with suitable backbones to carbonyl trimetal clusters, thereby stabilizing them, or making selective cluster formation possible. Coordinated isocyanides can be transformed readily into carbene ligands, which, in the future, could lead to complexes with polycarbene ligation.     

Self-Assembled Three-Dimensional Coordination Polymers with Unusual Ligand-Unsupported Ag−Ag Bonds: Syntheses,Structures, and Luminescent Properties

A staggered arrangement like that of the hydrogen atoms in ethane is exhibited by the six phenol groups about each pair of silver atoms in the self-assembled three-dimensional coordination networks [Ag₂(H₂L)₃]_nX_2n (H₂L=N,N′-bis(salicylidene)-1,4-diaminobutane; X⁻=NO₃⁻ or ClO₄⁻); the former is depicted (for clarity the H₂L ligands are represented by long rods and the Ag atoms by hatched circles). These solids contain short ligand-unsupported metal–metal bonds and display intense blue photoluminescence at room temperature.     

Multi‐dimensional Copper(II) Coordination Polymers via Self‐assembly Induced by Sodium Ions

Two novel copper(II) coordination polymers, [CuNa₂(Hnta)₂]_n ( 1 ) and {[CuNa₂(pht)₂(H₂O)]·H₂O}_n ( 2 ) (H₃nta = nitrilotriacetate acid, H₂pht = o‐phthalic acid), have been synthesized and characterized.The sodium ions play an important role in the formation of the multi‐dimensional structures. The X‐ray structure of [CuNa₂(Hnta)₂]_n ( 1 ) is three‐dimensionally cross‐linked with building blocks [Cu(Hnta)₂]^2—connected by three sodium ions. The structure of {[CuNa₂(pht)₂(H₂O)]·H₂O}_n ( 2 ) can be described as pht units connected by Na ions via Na—O bonds to form chains, which are linked by Cu^II ions to make a 2D network. The IR spectra and thermal properties are also reported.     

Methoxide Coordination at the Pocket of [CuIITpCum,Me] and a Simple Model for the Cu Center of Galactose Oxidase

An unusually negative oxidation potential is found for the tyrosine residue in the center of fungal galactose oxidase. The complex [Cu(Tp^Cum,Me){O(MeS)C₆H₄}] (see picture on the right; Tp^Cum,Me=hydrotris(pyrazolyl)borate) offers insight into the mode of (cysteinyl-tyrosine) coordination to the copper center, and the reason for the low oxidation potential.     

Synthesis of N-Methyl-2-Thioimidazole Resin and Its Complex Behavior for Noble Metal Ions

The functional group capacity and the percentage of functional group conversion of crosslinked polystyrene resin bearing N-methyl-2-thioimidazole (MTIR) synthesized under optimum conditions are as high as 4.08 mmol/g resin and 96.0%, respectively. The apparent activation energies of sorption of MTIR for Au(III) and Pt(IV) are 13.1 and 13.4 kJ/mol, respectively. The sorption behavior of MTIR for Au(III), Pt(IV), and Pd(II) obeys the Freundlich and Langmuir isotherms. The sorption capacities of MTIR for Au(III), Pt(IV), and Pd(II) are as high as 4.33, 2.12, and 2.33 mmol/g resin, respectively. Au(III), Pt(IV), and Pd(II) adsorbed on MTIR can be eluted quantitatively by the eluant. The resin can be regenerated easily and reused without an obvious decrease in the sorption capacity for Au(III) and Pd(II). The resin has high sorption selectivity for noble metal ions. Au(III) can be separated quantitatively in the presence of high concentrations of Cu²⁺, Fe³⁺, Ni²⁺, and Mn²⁺. The recovery of platinum from the spent industrial catalysts is 98.6% by MTIR. The preconcentration and separation of palladium and platinum from the anode deposits of electrolysis of crude copper have been investigated. The resin may have potential industrial uses.     

A Series of Transition Metal Coordination Polymers Bearing 1,4‐Phenylenediacetate

The reactions of transition metal salts or hydroxide with 1,4‐phenylenediacetic acid (H₂PDA) in the presence of ancillary ligands 4,4′‐bipyridine (4,4′‐bpy) or imidazole (Im) produced five coordination polymers with the empirical formula [M(PDA)(4,4′‐bpy)(H₂O)₂]_n [M = Mn ( 1 ), Ni ( 2 )], [Cu(PDA)(4,4′‐bpy)]_n · 2nH₂O ( 3 ), [Ni(PDA)(Im)₂(H₂O)₂]_n · nH₂O ( 4 ), and [Cu(PDA)(Im)₂]_n · 2nH₂O ( 5 ). Their structures were determined by single‐crystal X‐ray diffraction analyses. The isomorphous 1 and 2 present a two‐dimensional sheet constructed by two kinds of one‐dimensional chains of –Ni^II–PDA^2––Ni^II– and –Ni^II–4,4′‐bpy–Ni^II–. Compound 3 features dinuclear subunits, which are further connected by two PDA^2– ligands and two 4,4′‐bpy ligands along (001) and (011) directions, respectively, to build a two‐dimensional sheet with the topology (4².6⁷.8)(4².6) different from those of 1 and 2 . Both 4 and 5 show one‐dimensional chain structure. The difference of compound 4 and 5 is that the two carboxylato groups of PDA^2– in 4 adopt monodentate coordination modes, whereas the two carboxylato groups of PDA^2– in 5 chelate to the metal ions. Magnetic susceptibility data of 1 were measured. Magnetically, 1 presents a one‐dimensional chain with a weak antiferromagnetic interaction (J =–0.064 cm^–1) between the intrachain Mn^II atoms mediated by 4,4′‐bpy.     

The Pentazadienide Ion as a Ligand in Metal Complexes

The pentazadienide ion is a surprisingly versatile ligand. The planar, zigzag N₅ chain can utilize its atoms N1, N3, and N5 to complex one, two, or three metal atoms in a monodentate or bidentate fashion. Of particular interest is the ligand's ability to promote short metal-metal contacts in complexes with d¹⁰ metal ions.     

Reactivity of cationic decamethylmetallocene complexes towards ketones

Reaction of decamethylmetallocene cations [Cp∗₂M]⁺ (M = Sc, Ti, V) with acetone and benzophenone resulted in the formation of the corresponding acetone adducts [Cp∗₂M(OCMe₂)_n]⁺ (M = Sc, n = 2; M = Ti, n = 1; M = V, n = 1) and benzophenone adducts [Cp∗₂M(OCPh)]⁺. The stoichiometry of these adducts is determined by both the electronic configuration of the metal center as well as steric pressure imparted by the large Cp∗-ligands. In addition, the M-O-C angle is controlled by the number of free valence orbitals of the Cp∗₂M unit.     

[B(O–C6H4–CN)4]– based Silver and Copper Coordination Polymers

A series of new coordination polymers bearing the [B(O–C₆H₄–CN)₄]^– anion was synthesized. Two new, one dimensional coordination frameworks of the type M[B(O–C₆H₄–CN)₄] (M = Ag, Cu) were obtained by salt metathesis. The reactivity towards organic Lewis‐bases was studied. The reaction with bidentate ligands yielded two dimensional networks with the general formula [M(L)][B(O–C₆H₄–CN)₄] {L = 2,2′‐bipyridine, 4,4′‐bipyridine, 1,2‐bis(pyridyl)ethane, 1,4‐diazabicyclo[2.2.2]octane}. The synthesis, properties and single crystal structure are reported.     

Coordination properties of axially unfixed chiral dipyridine ligands towards metal and ammonium ions

New chiral dipyridine ligands with an axially unfixed 1,1′-biphenyl bridge were prepared via homocoupling of bromophenyl pyridines. The conformeric ratios of the free ligands in solution and their coordination properties towards metal ions were studied by NMR spectroscopy. X-Ray crystallography of the silver(I) and copper(I) complexes showed 1:1 metal to ligand complexes and S planar chirality. Interestingly, the biphenyl ligands show a 1:2 stepwise binding towards most ammonium ions tested with strong fluorescence enhancement, but a selectively 1:1 binding towards l-ornithine methyl ester hydrochloride with no fluorescence enhancement.