Perfluormethyl‐Element‐Liganden. XIX. Koordinationsfähigkeit von Liganden des Typs Me_nP(CF₃)_3−n (n = 0–3)

Abstract

Zur Ableitung von Informationen über die Ligandeneigenschaften der Phosphane MenP(CF3)3−n (n = 0–3; Me = CH3) werden die bei der Synthese der BX3‐Addukte (X = H, Hal, Me) und der Komplexe M(CO)5L bzw. M(CO)4L2 gewonnenen Erkenntnisse und spektroskopischen Daten (IR, NMR) kritisch ausgewertet und mit den Bindungsmodellen von DOBSON u. Mitarb. [9] sowie BARBEAU u. Mitarb. [10] verglichen. Die Ergebnisse stützen die Beschreibung der MP‐Bindung als Kombination aus σ‐Donor‐ und π‐Akzeptoranteil.

Strategies for the synthesis of chiral, bidentate bis(perfluoroorganyl)phosphane ligands

“…(4) as has been established for the trifluoromethoxide anion [24]. (4) In terms of molecular orbital theory, this effect can be described as an electron donation from the phosphorus lone pair orbitals to s * -orbitals of C-F bonds. This activation of the C-F bonds could favor the decomposition of the dissolved compound, however in the solid state bis(trifluoromethyl)phosphanide salts exhibit a remarkable thermal stability.…”

“…Non-fluorinated diorganylphosphinous derivatives appear as phosphane oxides [8]. (1) Viewing the traditional phosphorus(III)-transition metal bond, [9] the strong p-acidity and weak s-basicity of perfluoroorganylphosphanes means, that the electron deficiency at the phosphorus atom will be transferred to the metal atom in the case of corresponding perfluoroorganylphosphane transition metal complexes [10,11]. This behavior indicates why perfluoroorganylphosphane ligands can be compared roughly with carbonyl and trifluorophosphane ligands.…”

“…The group electronegativity of a trifluoromethyl group for example exceeds the electronegativity of a chlorine atom [2]. Therefore perfluoroorganylphosphanes exhibit higher ionization energies [3] and reduced Lewis basicities [4] in comparison with their nonfluorinated counterparts. The high Lewis acidities [5] of perfluoroorganylphosphane derivatives are depicted by the readily addition of nucleophilic groups forming phosphoranides, PR 4 À [6].…”

“…Therefore perfluoroorganylphosphanes exhibit higher ionization energies [3] and reduced Lewis basicities [4] in comparison with their nonfluorinated counterparts. The high Lewis acidities [5] of perfluoroorganylphosphane derivatives are depicted by the readily addition of nucleophilic groups forming phosphoranides, PR 4 À [6]. The bonding of two CF 3 groups to a phosphorus atom effects a drastically decreased basicity, i.e.…”

Synthesis of the First Chiral Bidendate Bis(trifluoromethyl)phosphane Ligand through Stabilization of the Bis(trifluoromethyl)phosphanide Anion in the Presence of Acetone

“…The weak s basicity of trifluoromethyl-substituted phosphanes [5] causes these ligands to exhibit a lower trans effect than the nonfluorinated phosphane derivatives. This results in a shortening of the PtÀCl bond trans to the trifluoromethyl-substituted phosphorus atom of around 6 pm relative to the PtÀCl bond trans-coordinated with respect to the Ph 2 P moiety.…”