Abstract
The reaction between CpFe(CO) 2 Na and methyl-4-chloro-2-butenoate in tetrahydrofuran at -78°C gives CpFe(CO) 2 (η 1 -CH 2 CHCHCOOCH 3 ) (1). Photolysis of 1 in ether at -20°C yields {A figure is presented} (2). Attempts to prepare the corresponding η 5 -oxapentadienyl from 2 by thermolysis or photolytic activation were unsuccessful. Photolysis of 2 in the presence of the phosphine ligands R 3 P (R 3 P PMe 3 , P(OCH 3 ) 3 gives {A figure is presented} (PR 3 PMe 3 (3), P(OCH 3 ) 3 (4)). The molecular structure of 2 has been determined by an X-ray diffraction study. Crystallographic data: space group P2 1 /c, a 8.034(2), b 9.430(3), c 14.058(4)Å, β 94.42(2)°, Z = 4, R 3.49%, R w 4.05%. © 1989.