Heteronuclear iron-ruthenium complexes containing bridging allenyl and allenylcarbonyl ligands

Article abstract of DOI:10.1021/om00017a066

Reactions of Cp(CO)₂RuCH₂C≡CPh (1) with Fe₂(CO)₉ yield one or more of the products (CO)₃Fe(μ-η³:η²-C(O)C(Ph)=C=CH ₂)Ru(CO)Cp (2), (CO)₃Fe(μ₂-CO)RuCp(μ₂-CO)Fe(CO) ₃(μ₃-η¹-CCH=CHPh) (3), (CO)₃FeRu(CO)CpFe(CO)₃(μ₃-η ¹:η¹:η³-CCHCHPh) (4), (CO)₃FeFe-(CO)₃Ru(CO)Cp(μ₃-η ¹:η²:η²-C(Ph)=C=CH₂) (5), and (CO)₃FeFe(CO)₃Ru(CO)Cp(μ₃-η ¹:η²:η²-CH=C=CHPh) (6), depending on solvent, relative amounts of the reactants, and reaction time and temperature. The novel binuclear metal μ-allenylcarbonyl complex 2 is best prepared in THF at 0°C, whereas the capped trinuclear metal clusters 3 and 4 are obtained, along with 2, in diethyl ether at reflux. The trinuclear metal μ₃-η¹:η²:η²-allenyl products 5 and 6 result from the reaction of 1 with a large excess of Fe₂(CO)₉ in hexane at reflux. In the formation of 3, 4, and 6, a methylene hydrogen shift occurs within the C₃H₂Ph ligand. Reaction of 1 with Ru₃(CO)₁₂ in hexane at reflux affords (CO)₃RuRu(CO)₃Ru(CO)Cp(μ₃-η ¹:η²:η²-C(Ph)=C=CH₂) (7), which is structurally analogous to 5. Complex 2 undergoes monosubstitution at iron with each of PPh₃ and Ph₂PCH₂PPh₂ (dppm) at room temperature to yield 8 and 9, respectively. Thermolysis of (η¹-dppm)(CO)₂Fe(μ-η³:η ²-C(O)C(Ph)=C=CH₂)Ru(CO)Cp (9) affords disubstituted, dppm-bridged (CO)₂Fe(μ-η³:η²-C(O)C(Ph)=C=CH ₂)(μ-dppm)RuCp (10). Reaction of 5 with PPh₃ in hexane at reflux furnishes a monosubstitution product with Fe - PPh₃ bonding. All complexes were characterized by a combination of elemental analysis, mass spectrometry, and IR and ¹H, ¹³C, and ³¹P NMR spectroscopy. The structures of 2, 5, and 6 were determined by X-ray diffraction analysis. 2: monoclinic, P2₁/c, a = 7.037(5) A?, b = 17.20(1) A?, c = 29.69(2) A?, β = 95.58(5)°, Z = 8, R = 0.065, R_w = 0.074; 5: monoclinic, P2₁/c, a = 8.068(3) A?, b = 15.333(4) A?, c = 16.849(3) A?, β = 95.11(1)°, Z = 4, R = 0.037, R_w = 0.042; 6: monoclinic, P2₁/c, a = 8.999(4) A?, b = 12.914(6) A?, c = 36.15(1) A?, β = 93.46(2)°, Z = 8, R = 0.057, R_w = 0.075.