Phosphines tetradentate tertiary

NaCN and the tetradentate tertiary phosphine tris(o-diphenylphosphinophenyl)phos-phine (QP) give the neutral complex Fe(CN)2(QP) . ... 

Nb and Ta derivatives are hard acids and then-complexes with P- or As-donors are limited. Tertiary phosphines, especially PMes, have been widely used to stabilize low-valent derivatives. C-H activation reactions, promoted by the formation of thermodynamically stable Ta-H, Ta-C, and Ta=C bonds have resulted in metallacycles based on unusual anionic phosphorus donors. Nucleophilic Ta phosphinidene complexes could be stabilized by a tripodal tetradentate [NN3] amido ligand. The terminal PR ligand reacts smoothly with aldehydes, providing a general synthesis of phosphaalkenes RP=C(H)R and act thus as a phospha-Wittig reactant see Phosphorus Organophosphorus Chemistry). 

The tetradentate ligand (114) was prepared in high yield (96%) by HSiCl3 reduction of the corresponding tetra(tertiary)phosphine oxide.230... 

Complexes of the Q series are defined by their structure belonging to the [Tc P2L] complexes, with polydentate Schiff bases stabilized at the +3 oxidation state by a tertiary phosphine ligand (Deutsch et al. 1987). In fact, Tc(V)OC1-l-oxo complexes are easily reduced by a two-electron process to Tc(III). The final Tc(III) compound (Fig. 2.1.18) has an octahedral configuration with the two trans phosphines on the apexes and the tetradentate Schiff base on the equatorial plane (Jurisson et al. 1984). Tc-Q12 has a positive charge, the two hydroxyl groups being deprotonated. The Tc complex has been prepared in two steps, with an intermediate Tc(V)-oxo complex (Abrams et al. 1982). 

Several technetium(IIl) complexes containing both tetradentate Schiff-base and monodentate tertiary phosphine ligands have been synthesized. [Tcj(acac)2enj (PPh3)2 was obtained by reaction of [TcOCU] with H2(acac)2cn and PPh 3 in methanol ... 

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