Inorganic Ferrocene Analogue [Fe(P₄)₂]^2–

Abstract

Inorganic metallocene derivatives containing only cyclo-P n ligands have been targeted for more than 20 years, but their syntheses have never been achieved by pursuing the conventional route of using P 4 phosphorus except for the generation of [Ti(η 5 -P 5 ) 2 ] 2− . Herein, we report a facile one-step method for the synthesis of the homoleptic iron complex [Fe(P 4 ) 2 ] 2− by the Zintl-phase-type precursor KP. 31 P NMR analyses indicate that upon dissolving the KP phase in ethylenediamine P 4 2− was generated only in the presence of 2,2,2-crypt. The amounts of cation-sequestering agents, the type of iron precursor, and their consuming ratio have a decisive impact on the yield of [Fe(P 4 ) 2 ] 2− . Both the Fe II and the Fe III precursors can oxidize P 4 2− to give a concomitant product [(P 7 )Fe(P 4 )] 3− , which can be partially inhibited by the addition of potassium to produce relatively pure crystalline [K(2,2,2crypt)] 2 [Fe(P 4 ) 2 ].

Synthesis, Structure, and Electrochemical Properties of 2,3,4,5-Tetraphenyl-1-Monophosphaferrocene Derivatives

“…Among the various heterometallocenes reported to date, monophosphaferrocenes are by far the most investigated [ 2 , 3 , 4 ]. Recently, a facile one-step method for the synthesis of “fully inorganic” ferrocene analogue was reported and [Fe(P 4 ) 2 ] 2− represents the closest all-phosphorus derivatives of iron to ferrocene [Fe(η 5 -C 5 H 5 ) 2 ] so far [ 5 ]. Phosphaferrocenes are commonly regarded as phosphorus ligands with weaker σ-donor properties than classical tertiary phosphines and stronger π-acceptor ability similar to that of phosphites P(OR) 3 [ 6 ].…”

“…The first is the reaction between P-phenyl-phosphole and [CpFe(CO) 2 ] 2 at high temperatures, which was developed by the Mathey workgroup in 1977 [ 21 , 22 ]. The phosphaferrocenes obtained through this route have a tendency to be contaminated by the 2-phenylated derivative appearing through the thermal [ 1 , 5 ]-sigmatropic shift of the P-phenyl substituent onto the phosphole ring. Therefore, this procedure provides a desired product with low yields [ 23 ].…”

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

“…The most intriguing feature of these complexes is the presence of energetically and sterically accessible lone pairs at each heteroatom. Among the various heteroelement derivatives reported to date, phosphaferrocenes are by far the most investigated. − The introduction of a phosphorus atom into the ferrocene backbone allows access to novel supramolecular complexes and coordination polymers of multidimensional topology with mixed σ/π coordination modes, which are not typical for the classical ferrocene species. − Additionally, monophosphaferrocenes − and pentaphosphaferrocenes have been applied in asymmetric homogeneous catalysis and synthesis of asymmetric phosphines, revealing the practical value of phosphaferrocenes. A better understanding of how the replacement of CH-units by phosphorus atoms affects the properties of ferrocene will lead to the effective design of new systems.…”

Ferrocene-based P-chiral amidophosphinate: stereoselective synthesis and X-ray structural study

“…Ferrocene, a "privileged" scaffold for chiral ligands and catalysts, plays an outstanding role in asymmetric organic synthesis both in academia and industry. 1 The ferrocene 2 and phosphaferrocene moieties [3][4][5] have played a significant role as a backbone in phosphine ligands due to steric bulkiness and planar chirality, easy accessibility and derivatization as well as their stability. In recent decades, an amazing number and variety of chiral ferrocene ligands have been used in asymmetric catalysis.…”