Tertiary phosphines electronic properties

Scheme 5 shows a group of alkynylgold(i) complexes for which the studies focused on the UV-VIS electronic absorption and emission properties. Most of these compounds are of the type [(L)AuC=CR], for which the methods of synthesis have been summarized above. The products were found to show phosphorescence in various polymorphs and crystal forms of solvates. Although there are no metallophilic interactions discernible in the crystal between most of the monomers due to the steric effect of the large tertiary phosphines, there is nevertheless strong excitonic coupling based on other weak interactions, which depend on the organization of the molecules in the crystal.105,106... 

Dihalobis(tertiary phosphine)nickel(II), [NiX2(PR3)2], may be either square planar or pseudotetrahedral spedes depending on the steric and electronic properties of the phosphine and, in a few cases, on the nature of the halide. 

Halogen-bridged platinum(II) complexes of the tertiary phosphines, arsines, etc., were then unknown and they had properties well worth studying for comparison with those of their palladium analogs. Also, they could be oxidized to platinum(IV)-bridged species, and these showed marked instability compared with their platinum(II) analogs. This led me to speculate that the electrons in the [Pg.7]

When tris-o-tolylphosphine was used as ligand the main product (Equation 13) was formed in ca. 84% yield by GC area analysis. No correlation of regioselectivity with electronic or steric properties was found for several different tertiary phosphines. The final step consisting of cis p-hydrogen elimination leading to the E product occurs stereoselectively because only one of the two possible conformations leading to elimination is favoured. 

The rhodium complexes are more resistant towards oxidative addition than their iridium counterparts and this is believed to be linked to steric crowding, especially when employing bulky tertiary phosphine ligands. Work by Wilkinson explored several aspects of the steric and electronic properties of the rhodium(i) analogues, but definite crystal structural confirmation of the reaction... 

Tertiary phosphine analogs have been prepared from [Rh(NO)2Cl],i. Nitrosyltris(phosphorus trifluoride)rhodium has been prepared from both rhodium(—I) and rhodium(I) complexes (equations 294-296). Their physical properties are listed in Table 90. The triphenylphosphine complex is quite reactive (Scheme 42). Both electronic and P NMR spectrometry show the equilibrium constant for the reaction (297) to be of the order of 10 moldm in dichloromethane, benzene or THF, so the reactivity of the complex cannot arise from the facile loss of a triphenylphosphine ligand. The invariance of the line width of the doublet at — 48.8 p.p.m. ( J(Rh-P) = 175 Hz) with solvent suggests that the species is unsolvated. This lack of dissociation makes the preparation of the bis(triphenylphosphine) complex to appear erroneous. ... 

Chromium(I) complexes, 702 alkyl isocyanides, 704-709 aryl isocyanides, 704-709 2,2 -bipyridyl, 709 electrochemistry, 713 electronic spectra, 712 ESR spectra, 712 IR spectra, 712 magnetic properties, 710 synthesis, 709 cyanides, 703 fluorophosphine, 716 isocyanides crystallography, 708 electrochemistry, 709 spectroscopy, 708 synthesis, 707 1,10-phenanthroline, 709 electrochemistry, 713 electronic spectra, 712 ESR spectra, 712 IR spectra, 712 magnetic properties, 710 synthesis, 709 tertiary phosphines dinitrogen, 713 tris(bipyridyl)... 

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