SYNTHESIS OF THE 1,2,3,4-TETRAMETHYLFULVENE-BRIDGED DIIRON COMPLEX (ETA-1 ETA-5-CH2C5ME4)FE2(CO)6 AND ITS REACTIONS WITH PHOSPHINES

1,2,3,4-Tetramethylfulvene was prepared by hydride abstraction from pe ntamethylcyclopentadienyl anion and was converted to the fulvene-bridg ed dinuclear complex (eta1:eta5-CH2C5Me4)Fe2(CO)6 by treatment with Fe 2(CO)9. Reaction of this complex with phosphine L (L = PMe3, PPh3, PH2 PCH2PPh2, or PPh2H) caused replacement of a CO ligand with L to provid e (eta1:eta5-CH2C5Me4)Fe2(CO)5L in high yield. The structure of (eta1: eta5-CH2C5Me4)Fe2(CO)5(Ph2PCH2PPh2) was determined by X-ray crystal st ructure analysis: C4OH36Fe2O5P2, monoclinic, P2(1)/a; a = 20.334(5) an gstrom, b = 10.978(2) angstrom, c = 18.525(5) angstrom, beta = 116.17( 2)-degrees, V = 3711.2(4) angstrom3, Z = 4. When Ph2P(CH2)2PPh2 Was us ed as L, each of the phosphorus atoms made a bond to a diiron unit to give the tetranuclear complex [(eta1:eta5-CH2C5Me4)Fe2(CO)5]2(mu-L). T he PPh2H complex (eta1:eta5-CH2CrMe4)Fe2(CO)5(PPh2H) rearranged in hot benzene to a new phosphido-bridged dinuclear complex, (C5Me5)Fe2(CO)4 (mu-CO)(mu-PPh2).