Preparation of diazoalkane complexes of iron(ii)

Abstract

Diazoalkane complexes [Fe(η⁵-C₅H₅)(N₂CAr1Ar2)(P–P)]BPh₄ (1, 2) [P–P = Ph₂PCH₂CH₂PPh₂ (dppe) (1), Ph₂PCH₂CH₂CH₂PPh₂ (dppp) (2); Ar1 = Ar2 = Ph (a); Ar1 = Ph, Ar2 = p-tolyl (b); Ar1Ar2 = C₁₂H₈ (c)] were prepared by allowing chloro compounds FeCl(η⁵-C₅H₅)(P–P) to react with diazoalkane in the presence of NaBPh₄. Phosphine complex [Fe(η⁵-C₅H₅)(dppe)(κ¹-PPh₂CH₂CH₂PPh₂)]BPh₄ (3) was also prepared. Treatment of diazoalkane complexes 1, 2 with acrylonitrile afforded 3H-pyrazole derivatives (4, 5), as well as a small amount of nitrile complex [Fe(η⁵-C₅H₅)(κ¹-NCC(H)CH₂)(P–P)]BPh₄ (6). The complexes were characterised spectroscopically (IR, NMR) and by X-ray crystal structure determination of [Fe(η⁵-C₅H₅){N₂C(C₁₂H₈)}(dppe)]BPh₄ (1c).