Tetraalkyl Hydroxymethylene-bisphosphonate and Dialkyl 1-Diphenylphosphinoyl-1-hydroxy-ethylphosphonate Derivatives by the Pudovik Reaction and Their Rearranged Products

The reaction of diethyl α-oxoethylphosphonate and diethyl oxobenzylphosphonate with diethyl phosphite, dimethyl phosphite, and diphenylphosphine oxide affords, depending on the substrates and conditions (nature and quantity of the amine catalyst, temperature, and solvent), the Pudovik adduct and/or the corresponding >P(O)–CH–O–P(O)< product formed by rearrangement. The nature of the substituent on the central carbon atom (a methyl or phenyl group) influences the inclination for the rearrangement. The asymmetric products (either adducts or rearranged species) with different P(O)Y functions (Y = RO or Ph) exhibit interesting NMR features.

Complexes of Dichlorogermylene with Phosphine/Sulfoxide-Supported Carbone as Ligand

Due to their remarkable electronic features, recent years have witnessed the emergence of carbones L2C, which consist in two donating L ligands coordinating a central carbon atom bearing two lone pairs. In this context, the phosphine/sulfoxide-supported carbone 4 exhibits a strong nucleophilic character, and here, we describe its ability to coordinate dichlorogermylene. Two original stable coordination complexes were obtained and fully characterized in solution and in the solid state by NMR spectroscopy and X-ray diffraction analysis, respectively. At 60 °C, in the presence of 4, the Ge(II)-complex 5 undergoes a slow isomerization that transforms the bis-ylide ligand into an yldiide.

Persistent, highly localized, and tunable [4]helicene radicals

We report a series of tunable and persistent [4]-helicene neutral radicals by chemical reduction of the [4]-helicenium cation analogue. EPR spectroscopy and DFT calculations indicate that the unpaired electron is localized at the central carbon atom.

Crystal structures of [IrCl2(NHCHPh)((dppm)(C(N2dppm))-κ3 P,C,P′)]Cl·5.5MeCN and [IrI(NHCHPh)(((dppm)C(N2))-κ2 P,C)(dppm-κ2 P,P′)]I(I3)·0.5I2·MeOH·0.5CH2Cl2: triazene fragmentation in a PCN pincer iridium complex

The structure of [IrCl2(C58H51N3P4)]Cl·5.5CH3CN or [IrCl2(NHCHPh)(((dppm)C(N2dppm))-κ 3P,C,P)]Cl·5.5CH3CN [3, dppm = bis(diphenylphosphino)methane; systematic name: dichlorido(1,1,3,3,7,7,9,9-octaphenyl-4,5-diaza-1,3λ5,7λ4,9-tetraphosphanona-3,5-dien-6-yl-κ2 P 1,P 9)(phenylmethanimine-κN)iridium(III) chloride acetonitrile hemihendecasolvate], resulting from an oxygen-mediated cleavage of a triazeneylidenephosphorane ligand producing a diazomethylenephosphorane and a nitrene moiety, which in turn rearrange via a Staudinger reaction and a 1,2-hydride shift to the first title complex, involves a six-coordinate IrIII complex cation coordinated by a facial PCP pincer ligand, a benzaldimine and two chlorido ligands. The pincer system features a five- and a seven-membered ring, with the central divalent carbon of the PCP pincer ligand being connected to a phosphine and a diazophosphorane. The chlorido ligands are positioned trans to the central carbon atom and to the phosphorus donor of the seven-membered ring of the pincer system, respectively. A chloride ion serves as counter-ion for the monocationic complex. The structure of [IrI(C26H22N2P2)(C26H22P2)(C6H7N)]I(I3)·0.5I2·CH3OH·0.5CH2Cl2 or [IrI(NHCHPh)((dppm)C(N2)-κ 2P,C)(dppm-κ 2P,P′)]I(I3)·0.5I2·CH3OH·0.5CH2Cl2 {4, systematic name: (4-diazo-1,1,3,3,-tetraphenyl-1,3λ4-diphosphabutan-4-yl-κP 1)iodido[methylenebis(diphenylphosphine)-κ2 P,P′](phenylmethanimine-κN)iridium(III) iodide–triiodide–dichloromethane–iodine–methanol (2/2/1/1/2)}, accessed via treatment of the triazeneylidenephosphorane complex [Ir((BnN3)C(dppm)-κ 3P,C,N)(dppm-κ 2P,P′)]Cl with hydroiodic acid, consists of a dicationic six-coordinate IrIII complex, coordinated by a bidentate diazomethylenephosphorane, a benzaldimine, a chelating dppm moiety and an iodido ligand. The phosphorus atoms of the chelating dppm are trans to the central carbon atom of the diazomethylenephosphorane and the iodide ligand, respectively. Both an iodide and a triiodide moiety function as counter-ions. The acetonitrile solvent molecules in 3 are severely disordered in position and occupation. In 4, the I3 − anion is positionally disordered (ratio roughly 1:1), as is the I− anion with a ratio of 9:1. The dichloromethane solvent molecule lies near a twofold rotation axis (disorder) and was refined with an occupancy of 0.5. Another disorder occurs for the solvent methanol with a 1:1 ratio.

Homopropargyl alcohol 5,5-diphenylpent-2-yne-1,5-diol

In the title compound, C17H16O2, the central carbon atom has a distorted tetrahedral geometry [spread of angles = 105.71 (8)–112.75 (9)°] for its bonds to a homopropargylic but-2-yn-1-ol moiety, a hydroxy group and two phenyl substituents. In the crystal, O—H...O hydrogen-bonding interactions link the molecules into [001] chains and C—H...π(ring) contacts consolidate the packing.

Homopropargyl alcohol 1,1-diphenylbut-3-yn-1-ol

The asymmetric unit of the title compound, C16H14O, contains one molecule with a central carbon atom having a distorted tetrahedral geometry made of a propargylic fragment, a hydroxy group and two aromatic rings. Directional interactions such as unusual O—H...π contacts are observed between the molecules in the crystal.

Crystal structure of 1,3-bis[(E)-benzylideneamino]propan-2-ol

In the title compound, C17H18N2O, the central carbon atom with the OH substituent and one of the (E)-benzylideneamino substituents are disordered over two sets of sites with occupancies of 0.851 (4) and 0.149 (4). The relative positions of the two disorder components is equivalent to a rotation of approximately 60° about the C—N single bond. In the crystal, the molecules are held together by O—H...N hydrogen bonds, forming simpleC(5) chains along theb-axis direction. In addition, pairs of the chains are further aggregated by weak C—H...π interactions.

Sc3CH@C80: selective 13C enrichment of the central carbon atom

The use 13CH4 methane or the synthesis of Sc3CH@C80 enables enhanced 13C enrichment of the carbon atom in the endohedral cluster.