REDUCTIVE DIMERIZATION OF [MO(C6F5)(CO)2(ETA-C7H7)] - SYNTHESIS AND CHARACTERIZATION OF THE BITROPYL COMPLEX [(MO(C6F5)(CO)2)2(ETA-6-ETA'6-C14H14)]2-

The complex [Mo(C6F5)(CO)2(eta-C7H7)] 1 can be reduced either chemical ly or electrochemically (E(pc) = -2.07 V vs. ferrocenium-ferrocene) by one electron to produce the bitropyl (bicycloheptatrienyl) complex [{ Mo(C6F5) (CO)2}2(eta6:eta'6-C14H14)]2- 2(2)-. The sodium salt produced by Na(Hg) reduction of 1 in tetrahydrofuran is extremely air sensitiv e, but replacement of the Na+ cations with [N(PPh3)2]+ yields a much m ore stable salt. With either counter ion, the complex 22 exists in sol ution as a mixture of three isomers: endo-endo; endo-exo; and exo-exo. The complex has been fully characterized by IR, H-1 and C-13 NMR spec troscopy, elemental analysis and a crystal structure of the endo-endo isomer of the [N(PPh3)2]+ salt. Oxidation of the bitropyl complex rapi dly cleaves the bridging C-C bond and returns complex 1.