PREPARATION OF TRICARBONYL(ETA-4-VINYLKETENE)IRON(0) COMPLEXES FROM TRICARBONYL(ETA-4-VINYL KETONE)IRON(0) COMPLEXES AND THEIR SUBSEQUENT CONVERSION TO TRICARBONYL(ETA-4-VINYLKETENIMINE)IRON(0) COMPLEXES

Reaction of tricarbonyl(eta-4-vinyl ketone)iron(0) complexes (CO)3(PhCH = CHC(R) = O)Fe(0) (R = Me, 1; Bu(n), 3; Bu(t), 5; Ph, 7) with organolithium reagents under an atmosphere of carbon monoxide gave products that were identified as tricarbonyl"(eta-4-vinylketene)"iron(0) complexes (CO)3(PhCH = CHC(R) = C = O)Fe(0) (R = Me, 2; Bu(n), 4; Bu(t), 6; Ph, 8) based on a crystal structure analysis of 2. Complex 2 crystallizes in space group P2(1)/c with a = 13.998 (6) angstrom, b = 7.955 (5) angstrom, c = 12.935 (5) angstrom, beta = 113.04 (3)-degrees, and Z = 4. A reaction pathway that postulates the intermediacy of a tricarbonyl (eta-3-vinylcarbene)iron(0) complex, 20, is discussed. Heating the tricarbonyl(eta-4-vinylketene)iron(0) complexes 6 and 2 with either tert-butyl, cyclohexyl, or 2,6-xylyl isocyanide at 80-degrees-C gave tricarbonyl "(eta-4-vinylketenimine)"iron(0) complexes (CO)3(PhCH = CHC(R1) = C = NR2)Fe(0) (R1 = R2 = Bu(t), 23; R1 = Me, R2 = Bu(t), 24; R1 = Me, R2 = C6H11, 25; R1 = Me, R2 = (2,6-Me2)C6H3, 26) via intermediate dicarbonyl(isocyanide) (eta-4-vinylketene)iron(0) complexes. The intermediacy of tricarbonyl(isocyanide)(eta-1-vinylcarbene)iron(0) complexes in this reaction is proposed.