CARBON NITROGEN CLEAVAGE AND CARBON CARBON COUPLING PROCESSES IN THE REACTIONS OF RU3(CO)12 WITH TERTIARY-AMINES

The reactions of triethylamine and ethyldiisopropylamine with Ru3(CO)12 promoted by Fe2(CO)4(P-(C6H5)­)2(µ-SCH2CH3)2 at 70 °C have been studied. In addition to the previously reported major product (µ-H)(µ3-η2-CH3C═NCH2CH3)RU3(CO)9 (1), the three other triruthenium products formed, (μ-H)(μ3-η3-CH2CH═NCH2CH3)Ru3(CO)9 (2), (µ-H)(µ3-η3-CH3CC(H)C═N(CH2CH3)2)Ru3(CO)9 (3), and (μ-H)(µ3-η3-(CH3CH2)2N═C(H)C(H)CCH2)Ru3(CO)9 (4), have been characterized by spectroscopic methods and in the case of 3 and 4 by solid-state structural investigations. Compounds 1 and 2 are structural isomers, both of which have undergone alkyl cleavage, while 3 and 4 result from C–C coupling of a C2 fragment to a (C2H4)N(CH2CH3)2 fragment. In the reaction of the bulkier ethyldiisopropylamine under the same conditions as above, only two trirutheniumamine products are formed, (μ-H)2(μ3-η2-HCC═N(CH-(CH3)2)2Ru3(CO)9 (5) and (µ-H)(µ3-η2-CC═N(CH(CH3)2)2Ru3(CO)9 (6), which were characterized by solid-state structural investigations and spectroscopic methods. It was found that 5 converts cleanly to 6 on heating, while the isomeric 1 and 2 or 3 and 4 do not interconvert. Variable-temperature 1H and 13C NMR studies revealed that the organic ligand in 3 and 4 exists in solution as two and four isomers, respectively. Mechanistic schemes are proposed that rationalize the formation of 1 and 2 versus 3 and 4 and tentatively explain why the bulkier amine does not undergo any C–N bond cleavage. Compound 3 crystallizes in the P1 space group with a = 10.967 (3) Å, b = 14.052 (4) Å, c = 8.148 (2) Å, α = 102.95 (2)°; β = 110.74 (2)°, and γ = 97.32 (3)°. Least-squares refinement based on 3358 observed reflections gave a final R value of 0.043 (Rw = 0.054). Compound 4 crystallizes in the monoclinic space group P21/c with a = 12.223 (3) Å, b = 8.347 (1) Å, c = 21.787 (5) Å, and β = 92.93 (2)°. Least-squares refinement of 4585 observed reflections gave a final agreement factor of R = 0.041 (Rw = 0.045). Compound 5 crystallizes in the orthorhombic space group P212121 with a = 15.444 (2) Å, b = 16.693 (2) Å, and c = 9.027 (1) Å. Least-squares refinement of 3706 observed reflections gave a final agreement factor of R = 0.037 (Rw = 0.039). Compound 6 crystallizes in the orthorhombic space group Pnma with a = 19.466 (4) Å, b = 14.610 (2) Å, and c = 8.167 (1) Å. Least-squares refinement of 3224 observed reflections gave a final agreement factor of R = 0.035 (Rw = 0.042). © 1990, American Chemical Society. All rights reserved.