676255-77-9Relevant academic research and scientific papers
Synthesis and reactivity of μ-butadienyl diruthenium cations
Dennett, James N.L.,Knox, Selby A.R.,Charmant, Jonathan P.H.,Gillon, Amy L.,Orpen, A. Guy
, p. 29 - 40 (2003)
Propargyl alcohols HC≡CCR2OH (R=H, Me or Ph) react with [Ru2(CO)(MeCN)(μ-CO)(μ-CH2)(η-C 5H5)2] (2) to form the allylidene complexes [Ru2(CO)(μ-CO){μ-η1,η3-C(CR 2OH)CH=CH2}(η-C5H5) 2] (4a, R=H; 4b, R=Me; 4c, R=Ph). Treatment of complexes 4a-c with HBF4 removes the hydroxide group as water, giving the 2-butadienyl complexes [Ru2(CO)(μ-CO)(μ-η2,η 3-CR2=CCH=CH2)(η-C5H 5)2][BF4] (5a, R=H; 5b, R=Me; 5c, R=Ph). The reactivity of 5a-c towards nucleophiles and bases is described. With hydride, 5a-c undergo nucleophilic attack at the C(R2) carbon to give the allylidene complexes [Ru2(CO)(μ-CO){μ-η1, η3-C(CR2H)CH=CH2}(η-C5H 5)2] (6a, R=H; 7, R=Me; 11, R=Ph) and, in the case of 5c, the butadiene complex [Ru2(CO)2(μ-η 2,η2-CPh2=CHCH=CH2)(η-C 5H5)2] (12) and the allene complex [Ru 2(CO)2(μ-η2,η2-CPh 2=C=CHMe)(η-C5H5)2] (13), formally due to attack at the μ-C and CH2 carbons, respectively. The complexes 5a-c react with methyl lithium to undergo nucleophilic attack predominantly at the C(R2) carbon, giving methylated allylidene complexes [Ru2(CO)(μ-CO){μ-η1,η 3-C(CR2Me)CH=CH2}(η-C5H 5)2] (6b, R=Me; 9, R=Me; 14, R=Ph). With 5b and 5c methyl lithium also acts as a base, abstracting protons to give the novel divinylcarbene complex [Ru2(CO)(μ-CO){μ-η 1,η3-C(CMe=CH2)CH=CH2}(η- C5H5)2] (8) and the μ-butatriene complex [Ru2(CO)2(μ-η2,η2- CPh2=C=C=CH2)(η-C5H5) 2] (15), respectively. Complexes 8 and 15 are formed exclusively by treating 5b and 5c, respectively, with diazabicyclo[5.4.0]undec-7-ene (DBU). Complexes 8 and 9 were also prepared in good yield by reaction of complex 2 with 2-methyl-1-buten-3-yne {CH2=C(Me)C≡CH} and t-butylacetylene, respectively. Treatment of complex 8 with HBF4 resulted in protonation at each of the methylene groups, affording 5b and isomeric [Ru2(CO)(μ-CO){μ-η2,η 3-CH(Me)=CC(Me)=CH2}(η-C5H 5)2][BF4] (10). The structures of 5b, 5c and 8 were established by X-ray diffraction.
