R. Wolf

Bicyclophosphoranes Containing Macrocycles

Abstract Pentacovalent Phosphorus containing Macrocycles, 1,2,7 have been obtained by a general method applicable to all α-ω diols.

ENANTIOSPECIFIC SYNTHESIS OF PENTACOORDINATED PHOSPHORUS COMPOUNDS X-RAYS DIFFRACTION STRUCTURE AND REACTION MECHANISM

Abstract It is shown that the synthesis of the optically active spirophosphorane 5 is enantiospecific. The structure and the configuration of the enantiomeric pure diastereoisomer, given by the reaction, has been established by X-rays diffraction. A mechanism accounting for the stereospecificity is proposed. The same selectivity has been observed for three other compounds.

Determination of thermodynamic and kinetic parameters for equilibria between two diastereoisomers by a polarimetric temperature-jump method. The application to five- and six-co-ordinate phosphorus compounds

The usefulness of a polarimetric temperature-jump method for the determination of thermodynamic and kinetic parameters for equilibrium reactions between optically active compounds has been demonstrated for five- and six-co-ordinated phosphorus compounds. Even when the equilibrium constant (Ke) for the reaction cannot be accurately determined, it is shown that, with an approximate value of Ke at one temperature, the dependence of Ke on temperature (ΔH⊖ and ΔS⊖) can be accurately determined using the above method.

Phosphocations with co-ordination number 2 and 3 : phosphenium–iminophosphonium bisphosphocations

New phosphocations containing phosphorus with co-ordination number 2 and 3 and deriving from Cl–P–NR2 AlCl4- have been obtained: chloroiminophosphonium compounds (2) and the bisphosphocations (phosphenium–iminophosphoniums)(3).

Complexe 1/1 entre le chlorodiethylamino phenyl iminophosphorane et le trichlorure d'aluminum. Determination structurale

The crystal and molecular structure of the title compound (Cl)(Et2N)2P = Ν — Ph AICI3 has been determined from X ray data by a direct method. The two nitrogen atoms (Ni and N3) are planar, the other one (N2) is pyramidal coordinated with the lone pair anti with respect to the Ρ — Cl bond. The Ρ—Ν bonds are of equal length with a mean of 1.60 Â. The ethyl groups are all twisted in opposite directions. Comparison of structural data with the ones of four tetracoordinated phosphorus compounds (2—5) allow us to assign a zwitterionic structure for complex 1, the positive charge being delocalized into the N3P molecular skeleton.

Synthesis, structures and coordination behaviour of [As(NR)3]3− trianions

Re-examination of the X-ray structure of the imido As(III) complex previously formulated as [{As(NtBu)3}2Li6]·benzene (1·benzene) indicates that the disorder within the [{As(NtBu)3}2Li6] cage can be better explained by the molecular formulae [{As(NtBu)3}2Li6]·[LiNHtBu]6 or [{As(NtBu)3}Li3·(tBuNHLi)3]. The syntheses and X-ray structures of the new complexes [{As(N(2-MeO-C6H4)3)}2Li6·2TMEDA] (3) and [As{N(2-py)}3·LiN(2-py)·3thf]2·2thf (4·2thf), containing [As(NR)3]3− anions, are reported. Attempts to prepare the heteroleptic trianion [As(NCy)2(NCH2Ph)]3−via reaction of the arsazane dimer [CyNHAs(μ-NCy)]2 (5) with PhCH2NHLi (1 ∶ 6 equivalents) led to the unexpected formation of Zintl compounds containing the As73− anion. The X-ray structure of [As7Li3·3(CyNH2)·3thf] 6 is also reported.

New Phosphenium Cations and Bis-phosphocations via Condensation between Chlorophosphines or Chlorophospheniums and Trimethylsilyl Derivatives

Abstract New phosphenium cations of general formula R2N-P+-X, with a variety of X group (-N=P+R2, -N=PR3, -C°N, -C=N=S, OR) are synthesized using trimethylsilyl derivatives as reagents.

Three identical bidentate ligands complexed with penta- and hexa-co-ordinate phosphorus: stereospecificity of the PV→ PVI transformation

The substitution of bidentate ligands for chlorine, in benzene solution, for phosphorus pentachloride, leads to the equilibrated phosphoranes (4)⇌(5). Because of its insolubility the bridged bispentaoxyphosphorane (4a) has been isolated. The addition of a weak base (dimethylformamide) in this system shows the existence of the (5)⇌(6) equilibrium. A stereospecific transformation PV→ PVI is obtained by the addition of an optically active strong base, (–)-brucine.

Bicyclic phosphanes: synthesis, stereochemistry, and conformation

From the new family of 2,8-dioxa-5-aza-1-phosphaIIIbicyclo[3.3.0]octanes (bicyclic phosphanes)(1)–(5), three derivatives (3)–(5) were studied by synthesis, oligomerization, and n.m.r. spectroscopy. Conformational analysis shows that the five-membered rings take on an envelope conformation. The orientation of the folds is known for the majority of the compounds. Comparison of stereochemical data between phosphanes (2)–(4) and the corresponding 1-phenyl-2,8-dioxa-5-aza-1-phosphaVbicyclo[3.3.0]octanes (bicyclic phosphoranes)(7a)–(9a) underlines the conformational consequences due to the change of hybridization of the nitrogen and phosphorus atoms.

Bicyclic phosphanes. Part 2. Spontaneous dimerization of a constrained bicyclic phosphane. The crystal and molecular structure of a tricyclic compound containing the dioxadiazadiphosphecine ring

The dimerization of 3,3,7,7-tetramethyl-2,8-dioxa-5-aza-1-phosphaIIIbicyclo[3.3.0]octane (1) leads to octahydro-2,2,6,6,10,10,14,14-octamethylbis-1,2,3-oxazaphospholo[2,3-b:2′,3′-g]-1,6,3,8,2,7-dioxadiazadiphosphecine (2), a tricyclic compound with sixteen atoms around the periphery. The preparation, identification, and the X-ray structure are described. A pathway for the formation of the dimer is suggested by the trans-position of the two phosphorus Ione pairs.