Reaction of ( η1-allenyl)dicarbonyl( η5-cyclopentadienyl)ruthenium with nonacarbonyldiiron: synthesis and characterization of iron-ruthenium mixed-metal products

Abstract

Reaction of Cp(CO) 2RuCHCCH 2 with Fe 2(CO) 9 in hexane at reflux affords four iron-ruthenium products: Cp(CO) 2 Ru(μ 3-η 1,η 2,η 3- C(O)CHCCH 2) Fe 2( CO) 6( 3), CO) 3 Fe(μ 2- CO) RuCp(μ 2- CO) Fe( CO) 3(μ 3-η 1- CCHCH 2) ( 4), Cp(CO) 2Ru( μ 4- η 1, η 3, η 3 η 1-CH 2CCHC(CH)CH 2)(CO) 3FeFe(CO) 2( μ 2-CO) Ru(CO)Cp ( 5) and (CO) 3FeRu(CO)CpFe(CO) 3( μ 3- η 1, η 1, η 3-CCHCH 2) ( 6), which were isolated and characterized. Complex 3 reacts with PPh 3 to yield the monosubstitution derivative Cp(CO) 2Ru( μ 3- η 1, η 3, η 3-C(O)-CHCCH 2)Fe 2(CO) 5(PPh 3) ( 10); both 3 and 10 were characterized spectroscopically and are thought to contain a Ru-bonded allenylcarbonyl ligand, which is attached to Fe 2(CO) 5L (L=CO,PPh 3) through the oxygen atom and the two CC double bonds. The trinuclear 4 is structurally analogous to the previously prepared (C.E. Shuchart, A. Wojcicki, M. Calligaris, P. Faleschini and G. Nardin, Organometallics, 13 (1994) 1999), from Cp(CO) 2RuCH 2CCPh and Fe 2(CO) 9, (CO) 3Fe( μ 2-CO)RuCp( μ 2-CO)Fe(CO) 3( μ 3- η 1-CCHCHPh) ( 1) and contains a μ 3- η 1-CCHCH 2 ligand capping an Fe 2Ru metal core. In solution, 4 and 1 undergo partial conversion to 6 and (CO) 3FeRu(CO)CpFe(CO) 3( μ 3- η 1, η 1, η 3-CCHCHPh) ( 2), respectively, in which the CCHCHR (R = H, Ph) ligand bridges the Fe 2Ru triangle in a μ 3- η 1, η 1, η 3 mode. Complexes 6 and 2 also equilibrate to mixtures of 6 and 4 and of 2 and 1, respectively, upon storage in solution. 1 reacts with 2 equiv. of PEt 3 in the presence of Me 3NO to afford the disubstituted (CO)(PEt 3) 2Fe( μ 2-CO)RuCp( μ 2-CO)Fe(CO) 3( μ 3- η 1-CCHCHPh) (4 bd9), in which the bridging CCHCHPh ligand retains its μ 3- η 1 bonding mode. In contrast, reactions of 1 and 4 with PPh 3 yield (CO) 2(PPh 3)Fe( μ 2-CO)RuCp( μ 2-CO)Fe(CO) 3( μ 3- η 1, η 1, η 3-CCHCHPh) ( 8) and (CO) 2(PPh 3)Fe( μ 2-CO)RuCp( μ 2-CO)Fe(CO) 3( μ 3- η 1, η 1, η 3-CCHCH 2) ( 7), respectively, which contain μ 3- η 1, η 1, η 3-CCHCHR ( R= H, Ph). The tetranuclear Fe 2Ru 2 complex 5 results from the coupling of two FeRu allenyl or related species between a terminal and a central carbon atom of their C 3 fragments. The structures of 4 and 8 (as 8·0.5CH 2Cl 2) were determined by X-ray diffraction analysis. 4: monoclinic, P2 1/n, a = 9.038(1) A ̊ , b = 15.062(6) A ̊ , c = 13.485(4) A ̊ , β = 99.16(1)°, Z = 4, R = 2.8%, R w = 2.9% ; 8·0.5CH 2Cl 2: monoclinic, C2/c, a = 39.851(9) A ̊ , b = 9.319(2) A ̊ , c = 21.156(5) A ̊ , β = 112.91(2)°, Z = 8, R = 4.02%, R w = 4.81% .