Synthesis of co-ordinated trans-1.2-di(cycloheptatrienyl)ethylene, a new cyclo-octatetraene dimer, and the X-ray crystal structure of an intermediate bis-phosphonium salt [Fe2(CO)6{η4,η′4-C16H16(PPh3)2}][PF6]2

Abstract

The dication (1) obtained from tricarbonyl (η⁴-cyclo-octatetraene) iron and PPh₃ afford the bis-phosphonium salt (6), X-ray structural studies on which reveal both phosphorus atoms attached to one of the C₇-rings; reduction of (6) with Na[BH₄] gives (7), a complex of the cyclo-octatetraene dimer, trans-1, 2-di(cycloheptatrienyl)ethylene.