Organometallic iron (II) hydrazines and hydrazones - Syntheses, characterisations and the X-ray crystal structures of [Fe(η⁵-Cp)(η⁶-C₆H₅NHNH ₂)]⁺PF₆^- and [Fe(η⁵ -Cp)(η⁶-p-MeC₆H₄NHN=CMe₂)] ⁺PF₆^-

The three new organometallic hydrazines [Fe(η⁵-Cp)(η⁶-RC₆H₄NHNH ₂)]⁺PF₆^-, Cp=C₅H₅, R=H, [1]⁺PF₆^-; m-Me, [2]⁺PF₆^-; p-MeO, [3]⁺PF₆^-, were synthesised and characterised. They were obtained in CH₂Cl₂ by reaction of the hydrazine monohydrate, NH₂NH₂·H₂O, with the corresponding precursors [Fe(η⁵-Cp)(η⁶-RC₆H₄Cl)] ⁺PF₆^-. Similarly to free conventional organic hydrazines, the organometallic hydrazines [1]⁺PF₆^- and [3]⁺PF₆^- react with acetone affording hydrazones formulated as [Fe(η⁵-Cp)(η⁶-RC₆H ₄NHN=CMe₂)]⁺PF₆^-, R=H, [6]⁺PF₆^-; p-MeO, [7]⁺PF₆^-. Likewise, the two other organometallic hydrazones containing the substituent groups R=0-Cl, [8]⁺PF₆^- and p-Me, [9]⁺PF₆^- were also obtained from their parent hydrazine precursors [4]⁺PF₆^- and [5]⁺PF₆^-, respectively. All the new compounds were characterised by elemental analysis and IR, UV - vis, ¹H- and ¹³C-NMR spectroscopy. The crystalline and molecular structures of [1]⁺PF₆^- and [9]⁺PF₆^- were determined by single crystal X-ray crystallographic analysis. Both structures show a cyclohexadienyl-like character at the coordinated C₆ ring of the phenylhydrazine and the p-methylphenylhydrazone with a folding angle of 6.0(5) and 7.1(6)°, respectively.