Chalcogenide centred gold complexes

Chalcogenide-centred gold complexes are an important class of compounds in which a central chalcogen is surrounded by several gold atoms or gold and other metals. They have special characteristics such as unusual geometries, electron deficiency and properties such as luminescence or non-linear optical properties. The best known species are the trinuclear [E(AuPR(3))(3)](+), 'oxonium' type species, that have high synthetic applicability, not only in other chalcogen-centred species, but in many other organometallic derivatives. The aurophilic interactions play an important role in the stability, preference for a particular geometry and luminescence properties in this type of derivatives (critical review, 117 references).     

Incorporation of organometallic Ru complexes into apo-ferritin cage

Spherical protein cages such as an iron storage protein, ferritin, have great potential as nanometer-scale capsules to assemble and store metal ions and complexes. We report herein the synthesis of a composite of an apo-ferritin cage and Ru(p-cymene) complexes. Ru complexes were efficiently incorporated into the ferritin cavity without degradation of its cage structure. X-Ray crystallography revealed that the Ru complexes were immobilized on the interior surface of the cage mainly by the coordination of histidine residues.     

Synthesis and characterization of mixed-valent manganese phosphonate cage complexes

The reaction of phenylphosphonic acid (PhPO(3)H(2)) with the mixed-valent basic oxo-centered manganese triangle [Mn(3)O(O(2)CCMe(3))(6)(py)(3)] (1; where py=pyridine) in the presence of a suitable base gives four different manganese clusters depending on the identity of the base. The syntheses and structural characterization of [Mn(18)(mu(3)-O)(8)(PhPO(3))(14)(O(2)CCMe(3))(12)(py)(6)(H(2)O)(2)] (2), [Mn(7)(mu(3)-O)(3)(O(3)PPh)(3)(O(2)CCMe(3))(8)(py)(3)] (3), [Mn(9)Na(mu(3)-O)(4)(mu(4)-O)(2)(O(3)PPh)(2)(O(2)CCMe(3))(12)(H(2)O)(2)(H(2)O)(0.67)(Py)(0.33)] (4), and [Mn(13)(mu(3)-O)(8)(OMe)(8)(O(3)PPh)(4)(O(2)CCMe(3))(10)] (5) are described. Complexes 4 and 5 are homovalent Mn(III) cages, while 2 and 3 contain divalent, trivalent, and/or tetravalent ions. All the manganese centers are valence-localized, the octahedral Mn(III) sites being recognizable by marked Jahn-Teller distortions. The magnetic properties of compounds 2-5 have been investigated in the polycrystalline state by magnetic susceptibility and high-field magnetization measurements, which reveal that spin ground states vary from 0< or =S > or =8. AC susceptibility measurements performed on 4 and 5, in the 1.6-10.0 K ranges show the presence of out of AC susceptibility signal (chi(M)') for 4, and an effective energy barrier (U(eff)) for the re-orientation of the magnetization is found to be 17 K, but for 5, the chi(M)' maximum is found to be below 1.5 K.     

Nickel complexes of chlorophyll derivatives

Nickel complexes of certain phorbine and amide derivatives of chlorophyll a were synthesized. Most of the chlorophyll a derivatives studied form nickel complexes when boiled in toluene with an equimolar amount of nickel acetylacetonate in high yield. The yields of the nickel complexes of the chlorophyll derivatives are determined by the stability of the starting ligand under the reaction conditions.     

Encapsulation of cationic ruthenium complexes into a chiral self-assembled cage

A chiral supramolecular assembly encapsulates the two cationic ruthenium sandwich complexes [CpRu(eta(6)-C(6)H(6))](+) and [CpRu(p-cymene)](+). The host-guest complexes K(11)[CpRu(eta(6)-C(6)H(6)) subset Ga(4)L(6)] (2) and K(11)[CpRu(p-cymene) subset Ga(4)L(6)] (3) were characterized by one- and two-dimensional NMR techniques as well as by electrospray mass spectrometry. Encapsulation of the prochiral complex [CpRu(p-cymene)](+) by the chiral host renders enantiotopic protons diastereotopic as evidenced by (1)H NMR spectroscopy.     

Chalcogenide derivatives of 1,2,5-triphenyl-1H-phosphole: structure and photophysical properties

Chalcogenide derivatives of triphenylphosphole (oxide (1), sulfide (2) and selenide (3)) were synthesized and characterized by X-ray diffraction studies. Intermolecular interactions were observed in the bulk molecular packing in terms of hydrogen bonding for 1 or π–π stacking for 3. One of the useful applications of the chalcogenide derivatives of triphenylphosphole has been demonstrated utilizing the photophysical properties of 1 to detect aromatic nitro compounds through fluorescence quenching.     

A push-and-pull model for allosteric anion binding in cage complexes

A series of electronic structure calculations has been carried out on an artificial anion binding host. The compound with four Pd(ii) cations and a total of eight bis-monodentate pyridyl ligands forms by self-assembly an interpenetrated double cage with three binding pockets. Through the use of a simple push-and-pull model connecting the potentials of the different sites, we are able to explain the allosteric effect observed in anion binding. Two factors seem to be particularly significant in the latter, namely the flatness of the potential in each binding pocket as well as the length of the ligand. Our results are found to be in excellent agreement with the experimentally observed structures.     

Survey of Chalcogenide Superconductors

The thread that runs through all research in the field of superconductivity is new physics through discovery of new materials. The knowledge of superconducting materials has become voluminous and complex. The comprehensive review of the superconducting materials is of particular importance. The main purpose of this report is to present the results of classification for chalcogenide superconductors. Superconducting critical temperature T_c, crystal-structure type and the references proper to these compounds are summarized. Brief survey of the superconductivity in chalcogen elements is also given. Furthermore, as representative sulfide and selenide, superconducting characteristics of CuRh₂S₄ and CuRh₂Se₄ will be shown.This revised version was published online in November 2005 with corrections to the Cover Date.     

Penta- and hexaruthenium carbonyl 'raft' complexes supported by monocarborane cage ligands

Reaction between [PPh4][closo-4-CB8H9] and [Ru3(CO)12] in refluxing toluene affords the unprecedented hexaruthenium metallacarborane salt [PPh4][2,3,7-{Ru(CO)3}-2,6,11-{Ru(CO)3}-7,11,12-{Ru(CO)3}-3,6,12-(micro-H)3-2,2,7,7,11,11-(CO)6-closo-2,7,11,1-Ru3CB8H6] (1a), which contains a planar Ru6 'raft' supported by a {CB8} monocarborane cluster. Addition of [CuCl(PPh3)]4 and Tl[PF6] to a CH2Cl2 solution of 1a results in simple cation replacement, forming the analogous [Cu(PPh3)3]+ salt (1b). The phenyl-substituted monocarborane [NEt4][6-Ph-nido-6-CB9H11] reacts with [Ru3(CO)12] in refluxing 1,2-dimethoxyethane to afford the pentaruthenium cluster species [N(PPh3)2][2,3,7-{Ru(CO)3}-3,4,8-{Ru(CO)3}-7,8-(micro-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H6] (2), after addition of [N(PPh3)2]Cl. Treatment of 2 with [CuCl(PPh3)]4 and Tl[PF6] in CH2Cl2 forms the zwitterionic complex [10,12-{exo-Cu(PPh3)2}-2,3,7-{Ru(CO)3}-3,4,8-{Ru(CO)3}-7,8,10,12-(micro-H)4-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H4] (3). Substitution of CO by PPh3 with concomitant cation replacement occurs on introduction of [AuCl(PPh3)], Tl[PF6], and PPh3 to a CH2Cl2 solution of 2, forming [Au(PPh3)2][2,3,7-{Ru(CO)2PPh3}-3,4,8-{Ru(CO)2PPh3}-7,8-(micro-H)2-1-Ph-2,2,3,3,4,4-(CO)6-hypercloso-2,3,4,1-Ru3CB8H6] (4). Crystallographic studies confirmed the cluster architectures in 1b, 2, and 3.     

Noncovalent trapping and stabilization of dinuclear ruthenium complexes within a coordination cage

A dinuclear ruthenium complex, [(η(5)-indenyl)Ru(CO)(2)](2), was noncovalently enclathrated within a self-assembled coordination cage. In the cavity, rapid cis-trans isomerization and ligand exchange between the terminal and bridging carbonyls were suppressed, and only the carbonyl-bridged cis configuration was observed by X-ray crystallographic analysis.     

Self‐assembly of anion‐binding supramolecular cage complexes

Three tetradentate ligands, in which two bidentate pyrazolyl–pyridine binding sites are connected by an aromatic spacer unit, have been used to prepare adamantoid tetrahedral cages of the form [Co₄L₆(X)][X]₇ (where X is a uninegative, noncoordinating counterion such as perchlorate, tetrafluoroborate, or hexafluorophosphate). In these complexes an approximately tetrahedral array of metal ions occurs, with a bridging ligand spanning each of the six edges of this tetrahedron; each metal ion is accordingly six coordinate and the cages can have either T or C₃ symmetry, depending on the ligand. The central cavity of each cage is occupied by an anion. In the cases where the anion is a good fit for the central cavity, it is tightly bound (no exchange in solution with external anions) and acts as a template for assembly of the cage, with a mixture of Co(II) and the bridging ligand in the correct proportions not assembling into the Co₄L₆ cage until the templating anion is added. With a longer bridging ligand, the central cavity is too large to encapsulate the anion completely, and accordingly the encapsulated anion can exchange freely with external anions; this behavior can be “frozen out” in the NMR spectra at low temperatures. The host–guest chemistry of the cage complexes is therefore strongly dependent on the size of the central cavity. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:567–573, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10101     

Stacked platinum complexes of the magnus' salt type inside a coordination cage

Neatly wrapped up: alternately stacked square-planar platinum(II) complexes inside a dinuclear coordination cage were prepared to give a discrete and soluble Pt(5) -array of the Magnus' salt type. Characterization of the complex in solution was complemented by an X-ray crystal structure of {[Pt(pyridine)(4)]? [PtCl(4)](2) @Cage}; this structure showed the linear, pentanuclear array within the cages and their circular packing into a hollow tubular superstructure.     

99mTc complexes of 1,3-propanedithiol derivatives

The labelling of 1,3-n alkylpropanedithiols and of 15-/1,3-dimercapto 2-propyl/ pentadecanoic acid by^99mTc has been performed by an exchange reaction with the hexachlorotechnetate ion^99mTcCl ₆ ^2– and by reduction of^99mTcO ₄ ^– with Sn/II/ in the presence of the ligand. The biological distribution of the exotechnetium complexes obtained by the latter method in mouse does not reveal a high tropism of these labelling compounds in relation to a particular tissue.     

Metal complexes of some 5-nitrosopyrimidine derivatives

M(ADNU) ₂ complexes [whereM=Cu(II), Ni(II), Pd(II) and Pt(II); HADNU=6-amino-1,3-dimethyl-5-nitroso-uracil], Co(ADNU)₃·5H₂O, Pt(ADNU)₂Cl₂·0.5H₂O, Pd(ADU)₂ and Pt(ADU)₂Cl₂ (where HADU=1,3-dimethyl violuric acid) have been synthesized and characterized by elemental analysis, IR, magnetic measurements and thermal analysis (TG and DSC). All the isolated complexes of formulasM(ADNU)₂ orM(ADU)₂ show a square planar geometry, whereas the others are octahedral. Both ligands coordinate in bidentate form through the nitrogen and oxygen atoms of the 5-nitroso and 6-oxide groups.

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Metall-Komplexe einiger 5-Nitrosopyrimidine

Zusammenfassung Komplexe des TypesM(ADNU)₂ [M=Cu(II), Ni(II), Pd(II), Pt(II); HADNU=6-Amino-1,3-dimethyl-5-nitroso-uracil], Co(ADNU)₃·5H₂O, Pt(ADNU)₂Cl₂·0.5H₂O, Pd(ADU)₂ und Pt(ADU)₂Cl₂ (mit HADU=1,3-dimethylviolursäure) wurden synthetisiert und mittels Elementaranalysen, IR, magnetischen Messungen und Thermoanalyse (TG und DSC) charakterisiert. Alle isolierten Komplexe der allgemeinen FormelnM(ADNU)₂ oderM(ADU)₂ waren von quadratisch planarer Geometrie, während die anderen sich als octaedrisch erwiesen. Beide Liganden komplexieren zweizähnig über die Stickstoff- und Sauerstoffatome der 5-Nitroso- und 6-Oxo-Gruppen.

     

Iridium nitrosyl complexes of 2-aminophenol derivatives

Summary The synthesis and characterisation of products obtained by the interaction between [Ir(NO)(MeCN)₂(PPh₃)₂]²⁺ and 2-aminophenol derivatives are reported. Tetracoordinate d⁸complexes of the type Ir(NO)(2-ap)(PPh₃) and pentacoordinate d complexes₆of the type [Ir(2-ap)(PPh₃)₃]⁺ where 2-ap=2-aminophenol, 2-amino-4-nitrophenol, 2-amino-5-methylphenol, 2-3-aminonaphthol and 2-amino-4-methylphenol are obtained. The Ir(NO)(PPh₃)₃ complex is always present as a byproduct. Physical properties, i.r. spectra and conductivity data of the complexes are tabulated. Reaction schemes for the formation of the three complexes are proposed and discussed.     

Charge-transfer complexes of phenylephrine with nitrobenzene derivatives

The molecular charge-transfer complexes of phenylephrine with picric acid and m-dinitrobenzene have been studied and investigated by IR, 1H NMR electronic spectra in organic solvents and buffer solutions, respectively. Simple and selective methods are proposed for the determination of phenylephrine hydrochloride in bulk form and in tablets. The two methods are based on the formation of charge-transfer complexes between drug base as a n-donor (D) and picric acid, m-dinitrobenzene as pi-acceptor (A). The products exhibit absorption maxima at 497 and 560 nm in acetonitrile for picric acid and m-dinitrobenzene, respectively. The coloured product exhibits an absorption maximum at 650 nm in dioxane. The sensitive kinetic methods for the determination phynylephrine hydrochloride are described. The method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time at 20 min.     

Control of the coordination structure of organometallic palladium complexes in an apo-ferritin cage

We report the preparation of organometallic Pd(allyl) dinuclear complexes in protein cages of apo-Fr by reactions with [Pd(allyl)Cl]2 (allyl = eta3-C3H5). One of the dinuclear complexes is converted to a trinuclear complex by replacing a Pd-coordinated His residue to an Ala residue. These results suggest that multinuclear metal complexes with various coordination structures could be prepared by the deletion or introduction of His, Cys, and Glu at appropriate positions on protein surface.