Heptafluorocycloocta-1,3,5,7-tetraenyl, Hexaf luoroc ycloocta-1 ,3,5 ,I-tetraenedi y I, Heptafluorotricyclo[ 4.2 .O .02i5]octa-3,7-dienyI, and Hexaf luorotricyclo[ 4.2.0. 02*5]octa-3,7-dienediyl Transition-Metal Compounds. Crystal and Molecular Structures of[ Fe( q-C5R5) (q'-heptafluorocycloocta-I ,3,5,7-tetraenyl) (CO),](1 q,5q)-hexafluorocycloocta-1,3,5,7-tetraenedlyl)], and [ Mn( (3~)-heptafluorotricyclo[ 4.2.0 .02i5]octa-3,7-dienyI) (CO),] Cyclooct at et raenes. Synthesis of (R = H, Me), [[Fe(rl-C~Ha)(Co)212(I.Lz-Octafluorocyclooctatetraene (OFCOT; 1) reacts with various transition-metal carbonyl anions to yield the 7'-heptafluorocyclooctatetraenyl complexes [M(q'-CJ?,)] (M = Mn(C0)5 (7), Re(CO)5 (161, Fe(C&5)(CO), (171, Fe(CsMeS)(CO), (24), Ru(CsH5)(CO), (27)), which in most cases are in dynamic equilibrium with small amounts of their heptafluorobicyclo[4.2.0]octatrienyl valence isomers 12,18,25, and 28, respectively. The formation of the bicyclic complex 18 has been shown to occur via initial formation of 17 and subsequent isomerization. The conformational dynamics of the fluorinated rings in these complexes have been examined. In all cases ring inversion with concomitant bond shift isomerization is slow on the NMR time scale. In complex 17 ring inversion has been shown to be slow on the NMR time scale. Complex 17 reacts with EPh3 (E = P, As) to yield the complexes [Fe(CsH6)(q'-C,F,)(CO)(EPhB)] (E = P (291, As (30)) as diastereoisomeric pairs that can be separated and that do not interconvert at room temperature. Kinetic investigations of the conversion of one diastereomer of 30 into the other have yielded the activation parameters E, = 23.0(*0.9) kcal mol-', In A = 26.1 (f1.4), AG* = 24.4 (h0.3) kcal mol-', pH' = 22.4 (f0.9) kcal mol-', and A S = -6.6 (f1.8) eu; these have been shown to represent minimum values for the inversion of the fluorinated ring. Comparison of the AG* value for 30 with that for ring inversion of a hydrocarbon analogue indicates that fluorination of the ring increases PG' for this process by 27.1 kcal mol-'. The fluorinated ring in the monosubstituted complex 17 reacts with a further 1 equiv of [Fe(CsHJ(CO),]-to yield the disubstituted ring compound 22. The valence isomer of OFCOT anti-perfluorotricyclo-[4.2.0.02,5]octa-3,7-diene (9) reacts with metal carbonyl anions to afford the mono-and disubstituted compounds 13, 19,20, and 21. An unusual transformation of the 7'-heptafluorocyclooctatetraenyl ligand to the pentafluorobenzocyclobutenone ligand has been shown to occur during chromatography. Single-crystals X-ray diffraction studies of complexes 17,24,22, and 13 have been carried out. X-ray data were collected on a Syntex P21 autodiffractometer at -110 "C, and structures were refined by the full-matrix least-squares method. For 17, a = 21.390 (5) A, b = 7.507 (1) A, c = 18.767 ( 5 ) A, 0 = 108.63 (2)O, monoclinic, C2/c, Z = 8, R = 0.053, and R, = 0.050 for 2660 reflections with F, 2 40(F,,). For 24, a = 15.307 (4) A, b = 13.952 (3) A, c = 9.058 (2) A, /3 = 92.01 (2)O, monoclinic, P2...
