Reaction of Methylene Bridged Diphosphines R2P-CH2-PRH AND RHP-CH2-PRH (R [dbnd] Me,Pri, But,CH2-Ph) with Transition Metal Carbonyls

Abstract

The PH-functional methylene bridged diphosphines R₂P-CH₂-PRH and RHP-CH₂-PHR have been synthesized using Cl₂P-CH₂-PCl₂ as a starting material. On reaction with Fe₂(CO)₉ oxidative addition and cleavage of the P-C-P-skeleton occur yielding cluster compounds, e. g. (CO)₉Fe₃(RR 'P-CH₂-PR)H (R [dbnd] Me, Prⁱ, Bu^t, CH₂-Ph, R' [dbnd] R or H) or (CO)₉Fe₃(μ₃PR)(μ₂PMeR)H.     

Solution Structure and Reactions of Lithium-Organophosphido Complexes

Abstract

Transition metal carbonyl complexes of phosphine (PH₃), primary and secondary phosphines may be deprotonated with methyllithium to give the lithiated derivatives (I, II) which were shown to be useful intermediates in template synthesis of unusual phosphorus ligands [1].     

Trends in Ring-Opening Metathesis Polymerization

Abstract

Several transition metal alkylidene complexes are first discussed as catalysts for the ring-opening metathesis reaction. A new ruthenium catalyst with a slightly enhanced reaction rate is introduced. The stereochemistry and kinetics of the catalysts are investigated with different norbornene derivatives. Then it is shown that MgCl₂ alone is a good heterogeneous catalyst for the ring-opening polymerization (ROMP) of norbornene compounds. This is the first catalyst which does not need activation by a transition metal compound or another organometallic cocatalyst. Applications of the ROMP reaction for the synthesis of polymer specialities covering conjugated liquid crystals and optically active polymers are shown. Poly(cyclopentadienylene vinylene) and sidechain liquid crystal polymers are discussed in more detail. Finally, the synthesis of liquid crystalline elastomers by incorporation of bifunctional monomers during the ROMP reaction is described. It is shown that this kind of polymer can be used for the fabrication of optically anisotropic materials.     

Purity and homotopy theory of coalgebras

We construct a combinatorical monoidal model category on simplicial flat cocommutative coalgebras over a Prüfer domain. The cofibrations are the morphisms which are pure as module maps.     

Multivariate Markov-switching ARMA processes with regularly varying noise

The tail behaviour of stationary R^d-valued Markov-switching ARMA (MS-ARMA) processes driven by a regularly varying noise is analysed. It is shown that under appropriate summability conditions the MS-ARMA process is again regularly varying as a sequence. Moreover, it is established that these summability conditions are satisfied if the sum of the norms of the autoregressive parameters is less than one for all possible values of the parameter chain, which leads to feasible sufficient conditions.Our results complement in particular those of Saporta [Tail of the stationary solution of the stochastic equation Y_n+1=a_nY_n+b_n with Markovian coefficients, Stochastic Process. Appl. 115 (2005) 1954-1978.] where regularly varying tails of one-dimensional MS-AR(1) processes coming from consecutive large values of the parameter chain were studied.     

Moments of charge distributions in the reaction92Mo+92Mo at 14.7 MeV/u

First and second moments of primary charge distributions were determined as a function of the total kinetic energy loss in the reaction⁹²Mo+⁹²Mo at an incident energy of 14.7 MeV/u. Up to energy losses of 200 MeV no significant drift of the first moments is observed. The second moments are in agreement with predictions of a stochastic model derived at lower bombarding energies.