SYNTHESIS AND REACTIVITY OF [(C2F5)2PCH2CH2P(C2F5)2]FE(CO)3

Reaction of (C2F5)2PCH2CH2P(C2F5)2 (1) with (benzylideneacetone)Fe(CO)3 gives [(C2F5)2PCH2CH2P-(C2F5)2]Fe(CO)3 ((dfepe)Fe(CO)3 (2)) in 59% yield. Photosubstitution of CO by L yields (dfepe)Fe(CO)2L (L = THF, P(OCH3)3, C2H4). The ethylene complex has been characterized by single-crystal X-ray analysis (C14H8F20FeO2P2, monoclinic, P2(1)/c, a = 10.806 (5) angstrom, b = 14.069 (5) angstrom, c = 15.415 (3) angstrom, beta = 101.61 (2)-degrees, V = 2295.4 (14) angstrom 3, and Z = 4) and shows an unusually short carbon-carbon double bond (1.362 (7) angstrom) indicating weak pi-back-bonding. Photolysis of 2 under 1 atm of acetylene yields the cyclopentadienone complex (eta(4)-C5H4O)Fe(CO)(dfepe) while irradiation in the presence of butadiene yields (eta(4)-C4H6)Fe-(CO)(dfepe). Three styrene complexes (eta(6)-C8H8)Fe(CO)(dfepe), (eta(2)-C8H8)Fe(CO)2(dfepe), and (eta(4)-C8H8)Fe(CO)(dfepe) were isolated when 2 was photolyzed in the presence of styrene. The structure of the eta(4)-styrene complex was verified by a single-crystal X-ray analysis (C19H12F20FeOP2, triclinic, P1BAR, a = 8.7382 (16) angstrom, b = 10.789 (3) angstrom, c = 15.652 (6) angstrom, alpha = 87.382 (16)-degrees, beta = 101.61 (2)-degrees, gamma = 73.857 (17)-degrees, V = 1262.9 (6) angstrom 3, and Z = 2). The eta(4)-styrene complex can be used as an efficient (dfepe)Fe(CO)-transfer agent. Photolysis of 2 under 1 atm of H-2 gave the fluxional cis-dihydride complex (dfepe)(CO)2Fe(H)2 (17). Attempted oxidative addition of Et3SiH to photogenerated (dfepe)Fe(CO)2 gave dihydride complex 17 and (Et3Si)2O. Photolysis of 2 in alkane solvents at temperatures from -50 to +25-degrees-C gave no evidence for oxidative addition adducts.