Phosphine Coordination Research Articles

Silver(I) diethylphosphite ? Bonding mode and phosphine co-ordination compounds ? a31P NMR study

Silver(I) complexes with the P/O ambidentate phosphito- and phosphinito-ligands are shown to adopt P-bonded structures in solution by means of31P n.m.r. spectroscopy.1J(Ag, P) of AgP(O)(OEt)2 represents the largest one bond silverphosphorus coupling constant reported so far. AgP(O)(OEt)2 forms co-ordination complexes of the stoichiometry [Ag{P(O)(OEt)2}(PBu 3 n )n], n=1, 2 or 3 which were characterized by31P n.m.r. spectroscopy.

ChemInform Abstract: THERMAL STABILITY OF ALKYLCOPPER(I) COMPLEXES COORDINATED WITH TERTIARY PHOSPHINES

AbstractDie Kinetik und der Mechanismus der Thermolyse der Titelkomplexe (I) und (II) werden im festen Zustand und in Toluol untersucht zur Klärung der Rolle der tert.‐ Phosphine bei der Stabilisierung der Alkyl‐Cu(I)‐Komplexe.

Thermal Stability of Alkylcopper(I) Complexes Coordinated with Tertiary Phosphines

Abstract Thermolysis of isolated alkylcopper(I) complexes having tertiary phosphine ligand(s) RCuLn (R=CH3, C2H5, n-C3H7, i-C4H9) in the solid state and in toluene has been studied in order to clarify the role of the tertiary phosphine ligand in stabilizing the alkylcopper(I) complexes. The distribution of the thermolysis products shows that the thermolysis of the alkylcopper complexes having ethyl or longer alkyl chain proceeds through a β-elimination mechanism. The rate of the thermolysis obeys the first order rate law, −d[RCuLn]/dt=k[RCuLn]. The activation parameters of the thermolysis were obtained from the temperature dependence of k and a compensation effect between ΔH\eweq and ΔS\eweq was demonstrated. The activation energy Ea of the thermolysis of RCu(PPh3)2 increases in the order of R=C2H5<n-C3H7<i-C4H9. Coordination of electron-donating tertiary phosphine decreases Ea and a linear relationship between ν(Cu–CH3) frequencies and Ea for thermolysis of the methylcopper complexes was observed. Addition of PPh3 into the toluene solutions of CH3Cu(PPh3)2(diethyl ether)0.5 and C2H5Cu(PPh3)2 causes some retardation of the thermolysis. The major role of the tertiary phosphine ligand in stabilizing the alkylcopper complexes is proposed to strengthen the Cu–C bond by changing the electronic state of copper atom. An energetic consideration based on Chatt and Shaw’s theory is given in order to account for the results concerning the stabilities of the alkylcopper complexes. Photolysis of the alkylcopper complexes takes a quite different decomposition pathway producing mainly RH from RCuLn.

PHOSPHORUS-31 MAGNETIC RESONANCE SPECTRA OF TERTIARY PHOSPHINE COMPLEXES OF IRIDIUM(III) CHLORIDE

Abstract Phosphorus-31 chemical shifts are reported for eleven compounds of the type mer-[Ir(Ph n R3-m P)3Cl3] where R is alkyl and n is 0, 1, or 2. The occurrence of two peaks in the ratio of 2:1 in the phosphorus-31 magnetic resonance spectra confirms the meridional stereochemistry for the compounds. The chemical shift upon coordination is upfield from the free ligand, which is somewhat unusual for tertiary phosphine coordination compounds. Some proton magnetic resonance spectra and electronic spectra are also reported.

A localized orbital interpretation of ESCA chemical shifts on phosphine co-ordination

Measured differences in the binding energies of the phosphorous and chlorine core electrons in PCl3 and POCl3 are interpreted in terms of the nature of the P–O bond using the results of localized orbital calculations

Reaction of Butadiene with Ethylene. IV. Synthesis of 1,4-Hexadiene by a Cobaltous Chloride-Ditertiary Phosphine Complex and an Organoaluminum Compound Catalyst

Abstract A new catalyst consisting of a cobaltous chloride-ditertiary phosphine complex and an organoaluminum compound was found to be effective for the selective preparation of 1, 4-hexadiene by the reaction of butadiene with ethylene. The effects of the reaction variables on the activity and on the selectivity in 1, 4-hexadiene formation were studied. It is considered that a coordination of the ditertiary phosphine on the catalytically activated intermediate is essential for the selective catalysis. A reaction mechanism is proposed which involves an activated hydrido-cobalt complex as intermediate.