Diphosphinomethanide/Phosphoniumbismethylide: A Novel Ligand Combination for Transition Metals

Abstract

4 +R-,FCHz 0 R3P=CH-SiHzCH3 -[R~P-CHZ-S~HZ-CH~] C1' -[R~PCH,ICIThe [(methylsilyl)methyl]phosphonium salt thus formed is transformed by transylidation with further ~l i d e '~' into the [(methylsilyl)methylene]phosphorane end product. Since this reaction with H3SiCH2Cl can take place twice (until complete silylation of the ylide function), Me3P-CH2 and Et3P-CH2 respectively afford the bis(sily1)methylenephosphoranes ( I ) and (2) in almost quantitative yields. With Et3P=CHCH3 the reaction must terminate at the stage of the monosilyl compound (3).3 RsP=CHz + 2 H3SiCH2C1 --+ 2 Et3P=CHCH3 + H3SiCHzC1 --+

Ein sechskerniger Gold(I)‐Komplex: [{(Ph3PAu)2C(PPh2AuPPh2)}2](ClO4)2

“…Da die Torsion um die C-S-Bindung mit der Aquilibrierung der unterschiedlichen Fluroatome verkniipft ist, kann diese Fragestellung rnit der "F-NMR-Spektroskopie qualitativ beantwortet werden"]. [1,5]-sigmatrope H-Umlagerung leicht ineinander umwandelbar sind, nehmen wir an, da13 das Mengenverhaltnis 8a:Sb:Scvon 60:40:0 auchdas relative Stabilitatsverhaltnis widerspiegelt. 8 a, b haben die typi-…”

Synthesis and structural characterization of binuclear gold(I) complexes derived from two new A-frame ligands

“…The move from the methylene to the vinylidene analogue (dppm to vdpp) turned out to have little structural consequences. As shown in a preceding report,18 the mo-(14) Schmidbaur, H.; Mandl, J. R.; Richter, W.; Bejenke, V.; Frank A.; Huttner, G. Chem. Ber.…”

“…One metal thereby is functioning as an activating neighboring group for the second metal center through reversible transannular interactions.1 These effects are quite pronounced also in a number of gold(I) complexes of dppm-type ligands2'5 (A), or, e.g., related 1,3-difunctional phosphinobis(methylide) metallacycles (C).6'11 Oxidation with equivalent quantities of halogen leads to some of the very few species with gold in the oxidation state +11 containing an Au-Au bond.5,8'11 With dihalomethane, stepwise oxidative addition takes place leading eventually to methylene bridging between Au(III) centers.12,13 For the gold(I) complexes of type A-C, X-ray structure data,2,3,6,14 UV/vis spectra,15 and 197Au Móssbauer re-sults4,5'16 have indicated that Au-Au interactions are not negligible, since, e.g., the two metal atoms have even shorter interatomic distances than the dimensions imposed by the ligand bite. The nature of this interaction has been the subject of very recent discussions, as experimental evidence is rapidly increasing not only for the limited field of A-frame complexes.17 (4) Schmidbaur, H.; Wohlleben, A.; Wagner, F.; van de Vondel, D. F.; van der Helen, G. P. Chem. Ber.…”

Bi-, tetra-, and poly-nuclear complexes of gold(I) and silver(I) with bis(diphenylphosphino)-methanide or -amide acting as six-electron donors

“…Instrumentation and general experimental techniques were as described earlier. 9 , 2 5 The yields, melting points, conductivities, and analyses are listed in the Table ).-To a solution of [AuCI(CH,PPh,)] (0.203 g, 0.4 mmol) in acetone (30 cm3) was added Ph2PCH2PPh, (0.154 g, 0.4 mmol). The solution turned yellow and a yellow precipitate was formed.…”