Pentakis(.eta.1-phosphinine)iron: Synthesis, Structure, and Mode of Formation

Abstract

In order to elucidate the preferred mode of coordination-( ) or ij6(«•)-we have reacted phosphinine (C5H5P) with the open ferrocene (2,4-Me2-7/5-C5Hj)2Fe. The product, pentakis(7i*-phosphinine)iron (1), was subjected to X-ray structural analysis: 1 crystallizes in the space group P2/n with the cell parameters a = 16.010

Aromatic heterocycles XII. Semiempirical PM3 study of Diels-Alder cycloaddition reaction of substituted phosphabenzenes

“…Special attention was paid to the charges of the centers of reactions: the carbon atom at position 4 and the phosphorus atom in order to establish the stronger [1], [4] dipole; this is more important in the case of polarisable dienophiles. From Table 3 we observed that the alkyl substituents decrease the energy of reaction.…”

“…In consequence the results of PM3 calculation, except some values for ethyl derivatives, are in agreement with the experimental data and the electronic e®ects of substituents. Atomic charges listed in Table 5 emphasized that the electron withdrawing group phenyl decreases the atomic charge at C4, while electron releasing groups methyl, ethyl, isopropyl, and tert-butyl increase the atomic charge at C4, thus the [1], [4] dipole is strengthen by alkyl groups and consequently the reactions energy of these compounds are lower. The positive charge of the phosphorus atom increases in the case of phenyl substituted phosphabenzenes in position 2,4 and 6.…”

Synthesis, Solid-State Structure, and Electronic Nature of a Phosphinine-Stabilizedtriangulo Palladium Cluster

“…Phosphinines themselves, and in some cases metal complexes thereof, have been the subjects of previous theoretical studies. [13,14] A recent example is the ab initio calculations of the homoleptic tris-(2,2'-biphosphinine) complex of tungsten with six h 1 (s) bonds. [20] Theoretical calculations have also been reported for the Pd 3 core, [21±23] but not yet for ligand-stabilized triangulo Pd 3 clusters.…”

“…[16] Phosphinines are known to have significant aromatic character; the lowest unoccupied molecular orbital (p*) of the parent compound PC 5 H 5 has a relatively high localization at phosphorus that suggests a high p-acceptor capacity. [13,14] The in-plane lone electron pair corresponds to the third highest occupied level at about À 10.0 eV, which can be compared with À 10.6 eV known for PH 3 . This implies pronounced s-donor properties.…”

“…Phosphorus-containing heterocycles such as phosphinines (formerly called l 3 -phosphorines or phosphabenzenes) are also capable of forming complexes with transition metal complexes; [13] a h 1 (s) or a h 6 (p) coordination mode is the most common. [13,14] Early examples are the chromium complexes 2 and 3, respectively. [15] In addition, other types of coordination have been reported.…”