Gold Fragments Research Articles

Synthesis and crystal structures of the gold–carbaborane complexes [9-exo-{Au(PPh3)}-9-(µ-H)-10-endo-{Au(PPh3)}7,8-Me2-nido-7,8-C2B9H8] and [10-exo-{Au2(PPh3)2}-10-endo-{Au(PPh3)}-7,8-Me2-nido-7,8-C2B9H8

Treatment of the salt [NEt4][10-endo-{Au(PPh3)}-7,8-Me2-nido-7,8-C2B9H9] with [AuCl(PPh3)] in CH2Cl2 afforded the digold complex [9-exo-{Au(PPh3)}-9-(µ– H)-10-endo-{Au(PPh3)}-7,8-Me2-nido-7,8-C2B9H8]. Deprotonation of the latter with NaH in tetrahydrofuran followed by addition of [AuCl(PPh3)] gave the trigold compound [10-exo-{Au2(PPh3)2}-10-endo-{Au(PPh3)}-7.8-Me2-nido-7,8-C2B9H9]. The crystal structures of the new compounds have been determined by X-ray diffraction. In the digold species one Au(PPh3) group is endo-bound to the nido-C2B9 cage, primarily through a connectivity [Au–B 2.28(1)A] with the boron atom which is in the β-site with respect to the two carbons in the open [graphic omitted] face. There is a weaker attachment [Au–B 2.37(1)A] to one of the α-boron atoms, while the other α-BH unit forms a three-centre two-electron B–H⇀Au bond with the second Au(PPh3) group [Au–B 2.28(1), Au–µ– H 1.9(1)A]. The latter gold fragment lies exo with respect to the open face of the carbaborane cage, with an Au–Au separation of 2.875(1)A. The structure of the trigold complex is formally related to that of its digold precursor by replacement of the µ–H atom in the latter by an Au(PPh3) moiety. This results in the molecule having an essentially isosceles triangle of gold atoms [Au–Au 2.691(1), 2.922(1), 3.010(1)A], asymmetrically bridged by the β-boron [Au–B 2.192(9), 2.227(7), 2.307(8)A] of the open [graphic omitted] face of the C2B9 cage. The NMR data (1H, 13C –{1H}, 31P –{1H} and 11B –{1H}) of the compounds are reported and discussed.

Localized argyria with chrysiasis caused by implanted acupuncture needles: Distribution and chemical forms of silver and gold in cutaneous tissue by electron microscopy and x-ray microanalysis

A case of localized argyria with chrysiasis caused by implanted acupuncture needles in a 41-year-old Japanese woman was studied by electron microscopy and x-ray microanalysis. Large amounts of silver granules with selenium and sulfur were detected around eccrine secretory cells in much greater amounts than around ductal cells. Many granules were also observed along the outer edge of the basement membrane but never within cells or intercellular spaces. The granules were also present around blood vessels, lymphatics and nerve fibers, and in elastic fibers. Small numbers of gold fragments were also seen, mostly within macrophages. These results suggest that silver deposits extracellularly as selenide and sulfide, whereas free gold is found intracellularly.

The GSI projectile fragment separator (FRS): a versatile magnetic system for relativistic heavy ions

The projectile fragment separator FRS designed for research and applied studies with relativistic heavy ions was installed at GSI as a part of the new high-energy SIS/ESR accelerator facility. This high-resolution forward spectrometer has been successfully used in first atomic and nuclear physics experiments using neon, argon, krypton, xenon, and gold beams in the energy range from 500 to 2000 MeV/u. For the first time relativistic xenon and gold fragments have been isotopically separated. In this contribution we describe first experiments characterizing the performance of this spectrometer.

Notes. Synthesis and nuclear magnetic resonance spectroscopy of the platinum–gold clusters [Pt(AuPPh3){P(CH2CH2PPh2)3}]+and [Pt(AuPPh3){N(CH2CH2PPh2)3}]+

The platinum–gold cluster complexes [Pt(AuPPh3){P(CH2CH2PPh2)3}]+ and [Pt(AuPPh3){N(CH2CH2PPh2)3}]+ were obtained by treatment of [PtH{P(CH2CH2PPh2)3}]+ or [PtH{N(CH2CH2PPh2)3}]+ with [AuCl(PPh3)], isolated as BPh4– salts, and characterized by 31P and 195Pt NMR spectroscopy. They contain five-co-ordinate platinum and two-co-ordinate gold fragments.

ChemInform Abstract: A Route to Trinuclear Platinum‐Gold Clusters.

AbstractThe addition of electrophilic gold fragments to (I) gives new A‐frame cluster complexes such as (III) and (IX).

Synthesis and characterization of gold adducts of [M(tppme)(P3)][M = Co, Rh, or Ir; tppme = 1,1,1-tris(diphenylphosphinomethyl)ethane]. X-Ray crystal structures of [Au{M(tppme)(P3)}2]PF6(M = Co, Rh, or Ir)

Treatment of a dichloromethane solution of [M(tppme)(P3)][M = Co, Rh, or Ir; tppme = 1,1,1-tris(diphenylphosphinomethyl)ethane] with the complexes [AuCl(PR3)](R = Me or Ph) and [Au2Cl2{Ph2P(CH2)nPPh2}](n= 1 or 2) in the presence of TlPF6 invariably affords the compounds [Au{M(tppme)(P3)}2] PF6·solvent (M = Co, Rh, or Ir). X-Ray crystallographic analyses of the three isomorphous compounds showed that the gold atom is bound to two pairs of phosphorus atoms belonging to the P3 units of two [M(tppme)(P3)] fragments; the gold atom has a co-ordination geometry intermediate between tetrahedral and square planar. The unexpected elimination of the phosphane ligand from the gold fragments and the lengthening of the P–P bonds in which insertion of gold occurs are indicative of significant interaction between the gold atom and the MP3 clusters.

A route to trinuclear platinum–gold clusters

New A-frame cluster complexes have been prepared by addition of electrophilic gold fragments to the Pt—Pt bond of [Pt2Cl2(μ-ppm)2], dppm = Ph2PCH2PPh2. For example, [AuCl(SMe2)] gave [Pt2Cl2((μ-AuCl)((μ-dppm)2] and [Au(NO3) (PPh3)] gave [Pt2Cl2(μ-AuPPh3)(μ-dppm)2]NO3. The complexes [(CH2)n(PPh2AuBF4)2] reacted with [Pt2Cl2(μ-dppm)2] to give [Pt2Cl2(μ-AuPPh2(CH2)nPPh2AuCl)(μ-dppm)2]BF4 when n = 1 or 2, but the bridged bis(A-frame) cluster complex [{Pt2Cl2(μ-dppm)2(μ-AuPPh2CH2)}2CH2](BF4)2 when n = 3. In contrast, CuCl reacted with [Pt2Cl2(μ-dppm)2] to give [Pt2Cl(CuCl2)(μ-dppm)2]. Attempts to synthesize A-frame clusters containing Pt2Ag, Pt2Cu, Pd2Au, or PdPtAu units were unsuccessful, and it is concluded that these units are considerably weaker than the analogous 3-center 2-electron bond of the Pt2Au unit. The AuCl unit is displaced from [Pt2Cl2(μ-AuCl)(μ-dppm)2] on reaction with diazomethane, with formation of [Pt2Cl2(μ-CH2)(μ-dppm)2]. Keywords: platinum, gold, cluster, copper, silver.

Distinctive chemo- and stereo-selective reactions of [Fe(CO) 2Cp] + and [AuPPh 3+ with the anionic thioketene complex, [W(CO) 5&[;C(OEt)(Ph)C(Ph)=C=S&];] −. Crystal structures of Z-[W(CO) 5&[;C(SFe[CO] 2Cp)C(Ph)=C(OEt)Ph&];] and E-[W(CO) 5&[;S=C(AuPPh 3)C(Ph)=C(OEt)Ph&];

Reaction of the unusual thioketone adduct [W(CO) 5&[;C(OEt)(Ph)C(Ph)=C=S&];]Li with [Fe(CO) 2CpI] gives two binuclear tungsten iron complex isomers of composition [W(CO) 5&[;C(SFe[CO] 2Cp)C(Ph)=C(OEt)Ph&];] that differ only in the position of the iron substituent at the extremely short C(carbene)S bond. Crystallization affords only the isomer in which the metal atoms are oriented trans, as is shown by the X-ray crystal structure. Both isomers have a Z configuration about the C=C double bond. Treatment of the same adduct with [AuC/PPh 3] affords a binuclear compound in which the tungsten and gold atoms are linked by a thione group. This conversion is also stereo-selective with regard to the alkene bond and only the E isomer is formed. The structure of the product [W(CO) 5&[;S=C(AuPPh 3)C(Ph)=C(OEt)(Ph)&];] was determined by X-ray diffraction. Comparison of structural features with the related thioaldehyde complex, E-[W(CO) 5&[;S=CHC(Ph)=C(Ph)(OEt)&];] reveals the significant electron-withdrawing effect of the gold fragment.

ChemInform Abstract: New AuPt2 A‐Frame Cluster Complexes.

AbstractAddition of corresponding gold fragments to the Pt‐Pt bond of the complex (I) leads to the formation of the cationic complex (IIa) or the neutral complex (IIIa).

Übergangsmetall-Carben-Komplexe, CXXXVII Darstellung zweikerniger Gold(I)-Biscarben-Komplexe durch Carbenübertragungen von Wolfram auf Gold

The binuclear tungsten(0) biscarbene complexes3 and4 react with tetrachloroauric acid (stochiometric ratio 1 : 2) to give the corresponding gold(I) complexes5 and6 involving the transfer of biscarbene ligands from two tungsten to two gold fragments. Preparation and spectroscopic data are described.

The Sutton Hoo Ship-Burial. II. The Gold Ornaments

Ost of the gold ornaments represent the very splendid outer harness of a princely apparel, doubtless the sword-belt and baldrick, and also a purse and the straps on which it was slung. From the point of view of sheer weight of gold, the chief find was a huge and heavy buckle, inlaid with niello ; but the harness included twentyeight other pieces, all richly jewelled with garnets and, in some instances, blue and white mosaic glass. We must remember too that the sword has a jewelled gold hilt and two hemi-spherical bosses of gold, jewelled with garnet and blue glass, on the sheath (PLATE IX). There are also a number of minor fragments of gold, including one or two unornamented strap-mounts, two jewelled filigree strips of great delicacy, and a tiny mount of gold foil in the form of an animal. The excavators also found various ornamental fittings of wood or a similar material that were plated with gold.