Synthesis, characterisation and reactivity of hydrazine complexes of iron(II)

Hydrazine complexes [Fe((RNHNH2)-N-t)((RCN)-C-2)L-4][BPh4](2) 1-3 and [FeH((RNHNH2)-N-1)L-4]BPh4 4 [R-1=H, Me, Ph, 4-MeC6H4, 4-ClC6H4, 4-O2NC6H4 or Me2NNH2; R-2 = 4-MeC6H4, Me or Ph; L = P(OEt)(3), P(OMe)(3) or PPh(OEt)(2)] were prepared by reacting nitrile complexes [Fe((RCN)-C-2)(2)L-4][BPh4](2) and [FeH((RCN)-C-2-)L-4]BPh4 with an excess of the appropriate hydrazine. Their formulation and geometry in solution were established by infrared and H-1 and P-31 NMR spectroscopy. Amidrazone derivatives [Fe{eta(2)-NH=C(R-2)(NRNH2)-N-1} L-4][BPh4](2) [R-2 = 4-MeC6H4, Me or Ph; R-1 = H or Me; L = P(OEt)(3) or P(OMe)(3)] were obtained by allowing nitrilehydrazine complexes to react in solution and their formation, involving a nucleophilic attack of the hydrazine on the cyanide carbon atom of the (RCN)-C-2 ligand, is also discussed. Reaction of the arylhydrazine complexes 1-4 with Pb(O2CMe)(4) at -30 degrees C in CH2Cl2 resulted in selective oxidation of the arylhydrazine ligand affording the aryldiazene [Fe((RN)-N-1=NH)((RCN)-C-2)L-4]-[BPh4](2) and [FeH((RN)-N-1=NH)L-4]BPh4 10 [R-1 = aryl;; L = P(OEt)(3) pr P(OMe)(3)] derivatives. Treatment of the arylhydrazine [Fe((RNHNH2)-N-1)((RCN)-C-2){P(OEt)(3)}(4)][BPh4](2) 1 (R-1 = Ph or 4-MeC6H4) with an excess of NEt3,resulted in a complicated reaction giving the five-co-ordinate aryldiazenido derivatives [Fe((RN2)-N-1){P(OEt)(3)}(4)]BPh4.