“…Thus, it appears that the dppm acts in 5 as a chelating ligand after replacement of a further CO group at Fe(1). The 31 P-{ 1 H} NMR spectrum of 5 contains doublets at d 34.95 and 12.75; the absence of a highfield signal similar to that at d À25.9 in the corresponding spectrum of 4, combined with the dramatic lowering of the 2 J P-P (1), Fe-P 2.305(2) and 2.310(2), Fe1-CCF 3 2.012(6) and 2.013(6), Fe2-CCF 3 1.956 (7) and 1.960 (7), Fe3-CCF 3 1.942 (7) and 1.964 (7), Fe1-CO 1.762 (8)-1.795(8), l 3 -Fe1-CO 2.108(6) and 2.098 (7), l 3 -Fe2-CO 2.070(6) and 2.059 (7), l 3 -Fe3-CO 1.924 (7) and 1.940 (8), Fe1-C8 2.352 (7) and 2.357 (7), Fe2-C8 1.801(8) and 1.814 (7) and C2-C3 1.418(9) and 1.419 (9). 10% Probability ellipsoids are shown.…”