Versatile coordination modes and transformations of the cyclooctatriene ligand in Ru(C8H10)L-3 (L = tertiary phosphine)

Reaction of Ru(eta(4)-C8H12)(eta(6)-C8H10) (1) or Ru(eta(4)-C8H11)(2) (2) w ith tertiary phosphines gives Ru(eta(4)-C8H12)L-3 [L = PMe3 (4a), PMe2Ph (4 b), PEt3 (4c), PEt2Ph (4d), P(n-Bu)(3) (4e)]. The cyclooctatriene moiety in 4a oxidatively adds to the ruthenium, giving RU(6-eta(1):1-3-eta(3)-C8H10) L-3 [L = PMe3 (3a), PMe2Ph (3b)]. Complexes 4c-e dissociate one phosphine l igand in solution, affording the (hydrido)ruthenium complexes RuH(eta(5)-C8 H9)L-2 [L = PEt3 (5c), PEt2Ph (5d), P(n-Bu)(3) (5e)]. Whereas prolonged hea ting of 4c at 70 degrees C caused disproportionation of the eta(4)-C8H10 mo iety giving a mixture of the cyclooctatetraene complex Ru(eta(4)-C8H8)(PEt3 )(3) (6) and RuH(eta(5)-C8H11)(PEt3)(2) (7), heating of 1 with PEt3, 4c, or 4d in the presence of 1,5-C8H12 at 70 degrees C gave Ru(eta(4)-bicyclo[4.2 .0]octst-2,4-diene)L-3 [L = PEt3 (8a), L = PEt2Ph (8b)]. The molecular stru ctures of 3b, 4c, 6, and 8b have been established by X-ray structure analys is.