Tetrakis(acetonitrile)copper(I) hexafluorophosphate catalyzed coumarin synthesis via pechmann condensation under solvent‐free condition

Tetrakis(acetonitrile)copper(I) hexafluorophosphate ( Cu(CH₃CN)₄PF₆) is used as an efficient catalyst in the Pechmann condensation reaction of phenols with ethyl acetoacetate leading to the formation of coumarin derivatives in excellent yields under solvent free conditions at ambient temperature. The method is simple, solvent‐free and gives excellent yields in a short reaction time. J. Heterocyclic Chem.,(2011).     

Synthesis and Crystal Structure of Tetrakis(dimethyl sulfoxide)copper(II) Hexafluorosilicate

A new complex of composition [Cu(DMSO)₄SiF₆] (I), where DMSO is dimethyl sulfoxide (CH₃)₂SO, has been prepared and characterized by X-ray diffraction. Crystals I are triclinic, space group P\(\bar 1\), Z = 2, a = 10.1772(4) Å, b = 10.3061(5) Å, c = 10.6071(5) Å, V = 1003.94 Å3, ρ_calc = 1.714 g/cm³.     

Blue Tetrakis(diisopropylamino)-cyclo-tetraborane and Yellow Tetrakis(tetramethylpiperidino)tetrabora-tetrahedrane

The colored boranes closo- 1 and cyclo- 2 are obtained upon dehalogenation of sterically hindered diaminodichlorodiborane(4) 3 . The TMP groups of 1 cause the formation of a tetrahedrane, whereas in 2 the diisopropylamino substituents stabilize the bent four-membered ring. TMP=2,2,6,6-tetramethylpiperidino.     

Dinuclear copper(I) and copper(I)/silver(I) complexes with condensed dithiolato ligands

The Cu(III) complex Pr 4N[Cu{S 2C=( t-Bu-fy)} 2] ( 1) ( t-Bu-fy = 2,7-di- tert-butylfluoren-9-ylidene) reacts with [Cu(PR 3) 4]ClO 4 in 1:1 molar ratio in MeCN to give the dinuclear complexes [Cu 2{[SC=( t-Bu-fy)] 2S}(PR 3) n ] [ n = 2, R = Ph ( 2a); n = 3, R = To ( 3b); To = p-tolyl]. The analogue of 2a with R = To ( 2b) can be obtained from the reaction of 3b with 1/8 equiv of S 8. Compound 2b establishes a thioketene-exchange equilibrium in solution leading to the formation of [Cu 4{S 2C=( t-Bu-fy)} 2(PTo 3) 4] ( 4b) and [Cu 2{[SC=( t-Bu-fy)] 3S}(PTo 3) 2] ( 5b). Solid mixtures of 4b and 5b in varying proportions can be obtained when the precipitation of 2b is attempted using MeCN. The reactions of 1 with AgClO 4 and PPh 3, PTo 3 or PCy 3 in 1:1:4 molar ratio in MeCN afford the heterodinuclear complexes [AgCu{[SC=( t-Bu-fy)] 2S}(PR 3) 3] [R = Ph ( 6a), To ( 6b), Cy ( 6c)]. Complex 6c dissociates PCy 3 in solution to give the bis(phosphine) derivative [AgCu{[SC=( t-Bu-fy)] 2S}(PCy 3) 2] ( 7c), which undergoes the exchange of [M(PCy 3)] (+) units in CD 2Cl 2 solution to give small amounts of [Cu 2{[SC=( t-Bu-fy)] 2S}(PCy 3) 2] ( 2c) and [Ag 2{[SC=( t-Bu-fy)] 2S}(PCy 3) 2] ( 8c). Complexes 6a and b participate in a series of successive equilibria in solution, involving the dissociation of phosphine ligands and the exchange of [M(PCy 3)] (+) units to give 2a or 3b and the corresponding disilver derivatives [Ag 2{[SC=( t-Bu-fy)] 2S}(PR 3) 2] [R = Ph ( 8a), To ( 8b)], followed by thioketene-exchange reactions to give [AgCu{[SC=( t-Bu-fy)] 3S}(PR 3) 2] [R = Ph ( 9a), To ( 9b)]. Complexes 9a and b can be directly prepared from the reactions of 1 with AgClO 4 and PPh 3 or PTo 3 in 1:1:3 molar ratio in THF. The crystal structures of 3b, 6b, 6c, 7c, and 9a have been solved by single-crystal X-ray diffraction studies and, in the cases of 7c and 9a, reveal the formation of short Ag...Cu metallophilic contacts of 2.8157(4) and 2.9606(6) A, respectively.     

Tetrakis(trimethylsilyl)tetrahedrane

Tetrakis(trimethylsilyl)tetrahedrane 3 has been synthesized upon irradiation of tetrakis(trimethylsilyl)cyclobutadiene 8, which can be prepared either by thermal nitrogen elimination from trimethylsilyl[1,2,3-tris(trimethylsilyl)-2-cycloprop-1-enyl]diazomethane 7 or by mild oxidation of cyclobutadiene dianion 9 with 1,2-dibromoethane. The structural characterization of tetrahedrane 3 has been achieved by X-ray crystallography. The surprising thermal stability of 3 - which is stable up to 300 degrees C - is discussed.