Photoelectron spectra of group V compounds. IX [1]. The relative perfluoroalkyl substituent effect

Pentafluoroethylated Compounds of Silicon, Germanium and Tin

“…Above at emperature of À40 8Ct he decomposition of excess LiC 2 F 5 to insolubleL iF and volatile tetrafluoroethylene facilitates its removal. The treatment of the Lewis acidic inorganic element chlorides SiCl 4 ,G eCl 4 and SnCl 4 with LiC 2 F 5 reveals element-specific reactivity patterns (Scheme 2). [18][19][20] While in the reactionw ith GeCl 4 the anticipatedf ormation of Ge(C 2 F 5 ) 4 becomes apparent, the increased Lewis acidity of SnCl 4 results in the precipitation of its diethyl ether complex followed by an unselective formation of various pentafluoroethyltinc ompounds.…”

“…Only in the case of GeCl 4 pentafluoroethylation with an excess of LiC 2 F 5 selectively furnished the homoleptic Ge(C 2 F 5 ) 4 (Scheme 10). [19] For SiCl 4 and SnCl 4 modified synthetic protocols are required to avoid the formation of mixtures of hypervalent or fluoride-bridged complexes.T he synthesis of Si(C 2 F 5 ) 4 excludes the introduction of C 2 F 5 groups via organometallic reagents due to the pronounced fluorophilicity of the final product. Therefore, direct fluorination of Si(C 2 F 5 ) 3 Et was utilized to build up the fourth C 2 F 5 substituent, whereby Si(C 2 F 5 ) 4 is obtained as ac olorless liquid with ar emarkable thermals tability compared to trifluoromethyl derivatives.…”

“…Inorganic perfluoroalkylated compounds exhibit in general remarkable properties with respect to non‐fluorinated derivatives due to the strong electron‐withdrawing character of these substituents . A quantum chemical study of trimethylphosphane and tris(trifluoromethyl)phosphane reveals the effects which are accompanied by the fluorination of the methyl groups.…”

“…[3] Inorganic perfluoroalkylated compoundse xhibit in general remarkable properties with respectt on on-fluorinated derivatives due to the strong electron-withdrawing character of these substituents. [4] Aq uantum chemical study of trimethylphosphane and tris(trifluoromethyl)phosphane reveals the effects which are accompanied by the fluorination of the methyl groups.The ionization energy IP v as well as the electron affinity EA v are lowered. This correlates with as tabilization of the HOMO and LUMO and is accompanied by ad ecreased nucleo-philicity of the lone pair and an increased Lewis acidity ( Figure 1).…”

Fluoroalkoxy-derivatives of trivalent phosphorus: synthesis and reactivity

“…simple and planar molecules, almost fully reproduce the photoelectron spectra of hydrocarbon analogues, although they are displaced towards higher ionisation potentials (IP). However, the effect of the perfluoroalkyl substituent, postulated 24 and defined as a shift towards higher IP (without changes in the sequence, energy differences, and symmetry type of the MO for the n and a MO of the central atom) when alkyl groups are replaced by perfluoroalkyl groups, is not a general rule for fluorinated molecules, because it requires a correspondence between the nature of the MO and the energies and symmetries of the fluorinated and hydrocarbon analogues. This is possible only subject to the condition of the complete localisation of the orbitals np on the fluorine atoms, which in its turn conflicts with the nature of the photoelectron spectra.…”