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A Kinetically Stabilized Ferrocenyl Diphosphene: Synthesis, Structure, Properties, and Redox Behavior
Author(s) -
Nagahora Noriyoshi,
Sasamori Takahiro,
Takeda Nobuhiro,
Tokitoh Norihiro
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400577
Subject(s) - chemistry , trimethylsilyl , bond length , crystallography , dihedral angle , moiety , homo/lumo , double bond , redox , atomic orbital , molecular orbital , yield (engineering) , stereochemistry , crystal structure , medicinal chemistry , molecule , hydrogen bond , inorganic chemistry , polymer chemistry , organic chemistry , physics , materials science , quantum mechanics , metallurgy , electron
A new, stable ferrocenyl diphosphene [Tbt‐PP‐Fc] ( 1 ) (Tbt=2,4,6‐tris[bis(trimethylsilyl)methyl]phenyl, Fc = ferrocenyl) was synthesized by the dehydrochlorination reaction of the corresponding diphosphane, [Tbt‐P(H)‐P(Cl)‐Fc] ( 8 ), with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in good yield. Diphosphene 1 is very stable in the solid state and also in solution. In the 31 P NMR spectrum (C 6 D 6 ), diphosphene 1 showed a low‐fielded AB quartet at δ 501.7 and 479.5 ppm with the coupling constant 1 J PP =546 Hz, which is characteristic of an unsymmetrically substituted trans ‐diphosphene. The molecular structure of 1 was established by X‐ray crystallographic analysis, which showed a trans ‐diphosphene with a C‐P‐P‐C torsion angle of 177.86(17)°. The phosphorusphosphorus bond length of 1 [2.0285(15) Å] which is considerably shorter than the typical PP single‐bond lengths (ca. 2.22–2.24 Å) and within the range of reported PP double‐bond lengths (1.985–2.051 Å) for diaryl diphosphenes, evidenced the PP double‐bond character of 1 in the solid state. In addition, the cyclic voltammograms of 1 showed reversible reduction and oxidation couples at −1.95 and +0.34 V versus SCE, respectively. The electrochemical results for 1 were reasonably supported by the DFT calculations, which suggested that the LUMO and HOMO orbitals should be mainly π* orbital of the diphosphene moiety and d orbitals of the iron( II ) atom, respectively.