COMPLEXATION OF 1,4,5,8,9,10-HEXAHYDROANTHRACENE (HHA) TO IRON OR RUTHENIUM - A BIS(DIENE)DIIRON HHA GEOMETRY, HYDROAROMATIC RUTHENIUM COMPOUNDS RELATED TO RU(ETA-6-THA)CL2(DMSO) (THA = 1,4,9,10-TETRAHYDROANTHRACENE - DMSO = DIMETHYL-SULFOXIDE), AND RU3(CO)12-CATALYZED HHA REARRANGEMENTS

The nonconjugated tetraene 1,4,5,8,9,10-hexahydroanthracene (HHA; I) reacts with Fe(CO)5 to afford mono- and bis(tricarbonyliron) derivatives 1 and 2, in which the hydrocarbon fragment is bound to iron as a eta4-diene (respectively tricarbonyl((1,10,11,12-eta4)-tricyclo[4.4.0.0(3,8)]tetradeca1(10),3(8),5,11-tetraene) iron (1) and anti-hexacarbonyl((8,3,4,5-eta4:1,10,11,12-eta4)-tricyclo[8.4.0.0.3,8]tetrade ca-1(10),3(8),4,11-tetraene) diiron (2)). Complex 2, which crystallizes in the space group P2(1)/c (a = 11.0617(7) angstrom, b = 12.239(2) angstrom, c = 6.9928(5) angstrom, beta = 105.82(6)-degrees, V = 910.9(9) angstrom3, Z = 2), has been characterized by using X-ray diffraction, establishing the anti disposition of the two Fe(CO)3 groups. Compounds 1 and 2 have been further characterized by using C-13 NMR spectroscopy. In the presence of Ru3(CO)12, HHA is converted catalytically to other anthracenes, mainly by isomerization. With hydrated ruthenium(III) chloride, HHA binds to Ru as a eta6-arene (i.e. 1,4,9,10-tetrahydroanthracene (THA; II), via aromatization in one terminal ring), as is illustrated in the crystal structure of the product Ru(eta6-THA)Cl2(L) (4, L = DMSO; space group P2(1)/n, a = 10.821(3) angstrom, b = 12.472(4) angstrom, c = 12.738(4) angstrom, beta = 107.63(7)-degrees, V = 1638(2) angstrom3, Z = 4), from which facile displacement of DMSO may be accomplished to give 6 (L = Me2pzH, pzH = pyrazole), 7 (L = PPh3), 8 (L = P(OEt)3), 9 (L = PMePh2), and 10(L = PCy3, Cy = cyclohexyl). The H-1 and C-13 NMR spectra of compounds 7-10 show different and shielding of H6,7 of the THA ligand attributable to ring current effects due to the proximity of the PPh3 ligand and identify selective coupling of C8a,10a to the P-31 nucleus in 7, i.e. consistent with the existence of an energy minimum during eta6-THA rotation.