Effect of Phosphorus Substitution in the Cyclopentadienyl Ring of Ferrocene: Combined Mössbauer Spectroscopy and DFT Studies

Abstract

A series of phosphaferrocenes with different numbers of phosphorus atoms and phenyl groups in the cyclopentadienyl ring were successfully synthesized and studied by Mössbauer spectroscopy. Revealed Mössbauer hyperfine parameters are in line with density functional theory (DFT) calculations. It was found that substitution of CH-units by phosphorus atoms in the cyclopentadienyl ring affects the population of the molecular orbitals related to iron. These changes influence on Mössbauer hyperfine parameters, especially on the quadrupole splitting values. Intermolecular vibrations were analyzed in terms of the Debye model of solids based on the temperature dependence of Mössbauer absorption. The characteristic lattice Debye temperatures and the intermolecular force constants were calculated for each studied sample.

Access to 1,2,3-triphospholide ligands by reduction of di-tert-butyldiphosphatetrahedrane

“…4). As reported for related complexes, 23,29,33 the 31 P and 13 C NMR resonances are shifted to lower frequency. The 1 J PP coupling constants ( 11 : 1 J AX = 397.1 Hz, 12 : 1 J AX = 393.4 Hz) are smaller compared to the signals of anionic 3 ( 1 J AX = 465.6 Hz, vide supra ).…”

“…These findings echo the results of earlier investigations where A and t BuCP have formed isomeric reaction products. 12 The synthesis of [Cp*M(η 5 -1,2,3-P 3 C 2 t Bu 2 )] ( 11 , M = Fe; 12 , M = Ru) from the isolated potassium salt 3 complements earlier studies, 29,33 demonstrating the potential of 3 for transition metal coordination. Furthermore, reactions of 3 with [Cp 2 Fe][BAr 4 F ] and [H(Et 2 O) 2 BAr 4 F ] resulted in oxidation and dimerisation, forming the hexaphosphane t Bu 4 C 4 P 6 ( 13 ).…”

“…Even though several 1,2,3-triphospholide salts were reported, the number of isolated 1,2,3-triphospholyl complexes is limited. 22–25,29,33 To test the utility of the newly synthesized triphospholide salts, we investigated the synthesis of triphosphaferrocenes using 3 (which was selected among 1–5 due to the superior isolated yield). 29,33 Dropwise addition of 3 to [Cp*FeCl(tmeda)] (tmeda = tetramethylethylene-1,2-diamine) afforded the complex [Cp*Fe(η 5 -1,2,3-P 3 C 2 t Bu 2 )] ( 11 , Scheme 2a), which was identified by its AA′X spin system with resonances at 116.3 ppm and at −17.8 ppm in the 31 P{ 1 H} NMR spectrum in C 6 D 6 .…”