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• 32843-50-8 (η5-Cp)FeBr(dppe) 

Relevant academic research and scientific papers

Paramagnetisches BF4, eine gemischtvalente metallorganische Verbindung

The red closed-shell diamagnetic complex (CO)5Cr-CN-Fe(dppe)Cp (1) is obtained from Na and Cp(dppe)FeBr.Oxidation with BF4 converts it into the dark brown paramagnetic title compound 2.The crystal structure of 2, featuring a close to linear Cr-C-N-Fe arrangement, shows no unusual molecular details related to the odd-electron nature of the complex.Spectroscopic data of 2, including a strong IT band at 1130 nm, indicate that 2 is a heterometallic mixed valence complex of class II with a high degree of delocalization.Key words: Chromium; Iron; Carbonyl; Paramagnetism; Phosphorus

Synthesis, redox chemistry, and mixed-valence phenomena of cyanide-bridged dinuclear organometallic complexes

21 new organometallic complexes of the type M-CN-M′ containing the building blocks M, M' = (CO)5Cr, (CO)5Mo, (CO)5W, Cp(CO)2Mn, Cp(CO)2Fe, Cp(CO)(CN)Fe, Cp(dppe)Fe, Cp(PPh3)2Ru, Cp(PPh3)Ni, and (PPh3)2Ag were obtained from the reagents M-CN and M-X (X = leaving group). Among them are five pairs of linkage isomers M-CN-M′/M-NC-M′. Structure determinations of (CO)sCr-CN-M′ with M′ = Fe(dppe)Cp, Ni(PPh3)Cp, Ag(PPh3)2 and of (CO)5Cr-NC-Fe(dppe)Cp have proved their identity and the linkage isomerism. Systematic variations of the v(CN) and v(CO) IR bands allow an assessment of the relative electron pair acceptor strengths of the building blocks M and M' and a reliable identification of the individual linkage isomers. All dinuclear complexes are redox-active, showing at least one reversible oxidation. The redox potentials are characteristically dependent upon the nature of the building blocks M and M′ and upon the orientation of the cyanide link (CN vs. NC). 6 oxidized complexes of the type [M-CN-Fe(dppe)Cp]+ were prepared chemically and isolated as PF6 or BF4 salts. The molecular structure of [(CO)sCr-CN-Fe(dppe)Cp]BF4 is not significantly different from those of the corresponding neutral Cr-CN-Fe or Cr-NC-Fe complexes. Upon oxidation the v(CN) band of the complexes shifts to lower wavenumbers and becomes much more intense. The oxidized complexes show the paramagnetism due to one unpaired electron. They give rise to very intense metal-to-metal charge-transfer bands in the near infrared region whose postion was found to be characteristically dependent on solvent polarity for [{CO)sCr-CN-Fe(dppe)Cp]BF4. A semiquantitative treatment of the optical and electrochemical measurements shows that the electron delocalization and metal-metal interaction in the oxidized dinuclear complexes is significant and that they belong to the class-II mixed-valence systems. VCH Verlagsgesellschaft mbH,.