Search Results

You are looking at 1 - 10 of 13 items

  • Author: Dietrich Gudat x
Clear All Modify Search


Ba2In crystallizes in the orthorhombic Ca2In structure type (Pnma (No. 62), a = 809.73(3) pm, b = 591.34(2) pm, c = 1093.90(4) pm, V = 532.79 cm3, Z = 4, R 1 = 0.028, wR 2 = 0.054). The structure can be rationalized as a hexagonal closed packing of In with occupation of all octahedral and trigonal bipyramidal holes by bariäum. A second modification as indicated in the available phase diagram could not be obtained. The presence of minor hydrogen impurities was revealed by chemical analysis and 1H NMR spectroscopy and is discussed in terms of hydride formation.

The reactions of 1,1-diamino-2,2-diphenyl-substituted diphosphines featuring various degrees of P-P bond polarization with different alkynes were investigated. All diphosphines reacted with alkynes carrying one or two electron withdrawing carboxylic ester moieties under cleavage of the P-P bond and stereospecific phosphinyl-phosphination at the triple bond to give unsymmetrical ethane-1,2- bisphosphines. Several of the products were further converted into chelate complexes upon reaction with group-10 metal dihalides. All isolated compounds were characterized by analytical and spectroscopic data, and several of the new ligands and complexes by single-crystal X-ray diffraction studies.

Reaction of chiral N-heterocyclic chlorophosphines with lithium diphenylphosphide or of achiral N-heterocyclic chlorophosphines with optically active lithium menthyl phosphide produces chiral N-heterocyclic diphosphines which can be utilized in subsequent diphosphination reactions with activated alkenes or alkynes. The reaction with alkynes proceeds stereospecifically to produce Zethylene- 1,2-bisphosphines which are readily converted to nickel(II) or palladium(II) complexes. Reactions with alkenes are synthetically less useful as the addition proceeds without any chiral induction at the newly formed stereocenters to yield inseparable mixtures of diastereomeric products. The molecular structures of chiral Z-ethylene-1,2-bisphosphine complexes and of a chiral N-heterocyclic chlorophosphine have been determined by single-crystal X-ray diffraction

Single crystals of the lanthanide(III) thiophosphates(V) with the composition M[PS4] (M = La-Nd, Sm, Gd-Er) are formed within seven days at 950 °C by oxidation of the lanthanide metals and red phosphorus with sulfur (molar ratio: 1 : 1 : 4) in evacuated silica tubes without using any flux to avoid the entrapment of e. g. alkali metal cations. Their crystal structure (tetragonal, I41/acd, Z = 16; e. g. La[PS4]: a = 1098,97(5); c = 1953,26(9) pm and Er[PS4]: a = 1062,41(5); c = 1892,38(9) pm for the borderline representatives discussed here) is built up by a distorted cubic closest packing of discrete [PS4]3− tetrahedra (d(P5+-S2−) = 203 - 204 pm; ∢(S-P-S) = 107 - 116°) where the M3+ cations are situated in one half of the tetrahedral interstices, the same way as S2− in the Pt2+ arrangement of the cooperite-type PtS structure. Therefore an eightfold sulfur coordination for both crystallographically independent M3+ cations results in the shape of a trigonal dodecahedron. The 31P-MAS-NMR spectra of La[PS4], Nd[PS4], Gd[PS4], and Er[PS4] are reported and discussed

Bis-triphenylphosphonio-isophosphindolide salts 1[X] react with Cu(I)-halides CuX to give isolable products of composition [(1)Cu2X3 ]. X-ray crystal structure analyses confirmed that for X = Br, Cl dinuclear complexes [(μ-1 )(μ-X)Cu2X2] with μ2, η1(P)-bridging cations 1 are formed, while for X = I a solid phase containing a salt (1)2[Cu4I6] and a complex [(1)2Cu4I6] with a terminal η1(P)-coordinated ligand 1 was obtained. The bonding parameters in the two types of complexes suggest that l i s a hybrid between a phosphenium cation and a phospholide anion whose π-system is less nucleophilic than the phosphorus lone-pair.31P NMR studies revealed that in solution in all cases binuclear complexes [(1)Cu2X3] are in dynamic equilibrium with small amounts of mononuclear species and free 1. The same equilibria were detected in the system 1[OTf]/CuOTf. NMR studies of ligand exchange reactions indicated that the stability of complexes [(1)Cu2X3 ] increases in the order X = OTf < I < Br, Cl, and titration of [(1)Cu2Br3] with Et4NBr allowed to determine the equilibrium constant of the complex formation reaction.