Synthesis, Structure, Electrochemistry, and Spectroelectrochemistry of Hypervalent Phosphorus(V) Octaethylporphyrins and Theoretical Analysis of the Nature of the PO Bond in P(OEP)(CH₂CH₃)(O)

Abstract

A variety of phosphorus(V) octaethylporphyrin derivatives of the type [P(OEP)(X)(Y)](+)Z(-) (OEP: octaethylporphyrin) (X = CH(3), CH(2)CH(3), C(6)H(5), F; Y = CH(3), CH(2)CH(3), OH, OCH(3), OCH(2)CH(3), On-Pr, Oi-Pr, Osec-Bu, NHBu, NEt(2), Cl, F, O(-); Z = ClO(4), PF(6)) were prepared. X-ray crystallographic analysis of eleven compounds reveals that the degree of ruffling of the porphyrin core becomes greater and the average P-N bond distance becomes shorter as the axial ligands become more electronegative. Therefore, the electronic effect of the axial substituents plays a major role in determining the degree of ruffling although the steric effect of the substituents plays some role. A comparison of the (1)H NMR chemical shifts for the series of [P(OEP)(CH(2)CH(3))(Y)](+)Z(-) complexes with those of the corresponding arsenic porphyrins, which possess a planar core, indicates a much smaller ring current effect of the porphyrin core in the severely ruffled phosphorus porphyrins. The electrochemistry, spectroelectrochemistry and ESR spectroscopy of the singly reduced compounds are also discussed. The OH protons of [P(OEP)(X)(OH)](+) are acidic enough to generate P(OEP)(X)(O) by treatment with aq dilute NaOH. X-ray analysis of P(OEP)(CH(2)CH(3))(O) reveals that the PO bond length is very short (1.475(7) A) and is comparable to that in triphenylphosphine oxide (1.483 A). The features of the quite unique hexacoordinate hypervalent compounds are investigated by density functional calculation of a model (Por)P(CH(2)CH(3))(O) and (Por)P(F)(O) (Por: unsubstituted porphyrin).

Synthesis of meta-methoxyphenyl substituted tetraazaporphyrin and corrolazine phosphorus(V) complexes

“…Synthesis of tetraazaporphyrin and corrolazine phosphorus(V) complexes. 16] so that the number of axial ligands of 1 and 4 can be determined (2 and 1, respectively). The MS spectra also supported their coordination number.…”

Phosphorus(V) tetrapyrazinocorrolazines — first corrolazine derivatives with fused heterocyclic rings

“…In the case of P V octaphenylcorrolazine the molecular ion of [(Ph 8 CA) P=OH + ] with m/z = 954 is accompanied by more intense [M+Na] + peak at m/z = 976. Since in both cases the elemental analysis indicated the presence of additional water molecule, the compounds obtained from water can be formulated either as hydrates [32], and cationic hydroxyphosphorus(V) complexes of corroles [31], tertbutylphenyl substituted corrolazine [20] and tetrabenzocorrolazine [13]. Since for the P V complex of octaphenylcorrolazine the resonance of the P atom in the 31 P NMR spectrum is observed at -112.7 ppm and the position of the new band appearing in its IR spectrum at 1213 cm -1 (Fig.…”

New Trends in Hexacoordinated Phosphorus Chemistry

“…Akiba investigated the electrochemical behavior of a variety of phosphorus octaethylporphyrin derivatives; all compounds showing a single reversible oxidation wave [91]. The absolute difference in potential between the first ringcentered oxidation and reduction varies from 2.19 to 2.36 V in dichloromethane.…”