Preparation of diazoalkane complexes of iron(II)

Diazoalkane complexes [Fe(eta(5)-C5H5)(N(2)CAr1Ar2)(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(eta(5)-C5H5)(P-P) to react with diazoalkane in the presence of NaBPh4. Phosphine complex [Fe(eta(5)-C5H5)(dppe)(kappa(1)-PPh2CH2CH2PPh2)]BPh4 (3) was also prepared. Treatment of diazoalkane complexes 1, 2 with acrylonitrile afforded 3H-pyrazole derivatives [Fe(eta(5)- C5H5)-{N=NC(Ar1Ar2)(CH(CN)CH2}(P-P)]BPh4 (4, 5), as well as a small amount of nitrile complex [Fe(eta(5)-C5H5)(kappa(1)-NCC(H)]= CH2)(P-P)]BPh4 (6). The complexes were characterised spectroscopically (IR, NMR) and by X-ray crystal structure determination of [Fe(eta(5)-C5H5){N2C(C12H8)}(dppe)]BPh4 (1c).