Abstract
CpFe(CO) 2 (η 1 -pentadienyl) (1) and the corresponding η 1 -2,4-hexadien-1-yl (3) undergo [4 + 2] cycloaddition with tetracyanoethylene and maleic anhydride to give the adducts CpFe(CO) 2 CH 2 CHC(CN) 2 C-(CN) 2 CH 2 CH=CH 2 (2) and CpFe(CO) 2 CH 2 CHCHCOOCOCHCHRCH=CH (R = H (4), CH 3 (5)) in moderate yields. Reflux of PPh 3 with 4 and 5 gave the acyl compounds in two diastereoisomers with good yields. Complex 1 undergoes insertion with alkynes dimethyl acetylenedicarboxylate and hexafluoro-2-butyne. The insertion products have been fully characterized by means of appropriate physical methods. The molecular structures of 2, 4, and 5 have been characterized by an X-ray diffraction study. Crystallographic data for 2: space group Pca2 1 ; a = 13.174 (2) Å, b = 10.601 (2) Å, c = 12.315 (3) Å; Z = 4; R F = 4.3, R wF = 3.0. For 4: space group P2 1 2 1 2 1 ; a = 8.167 (1) Å, b = 10.006 (2) Å, c = 17.700 (4) Å; Z = 4; R F = 2.7, R wF = 3.0. For 5: P2 1 /c, a = 9.197 (2) Å, b = 12.498 (3) Å, c = 13.622 (2) Å, β = 90.79 (2)°; Z = 4; R F = 3.2, R wF = 2.6. © 1988 American Chemical Society.