98838-13-2Relevant academic research and scientific papers
Reactions of HC≡CCO2Et with (np3)CoH and (np3)Ni [np3 = N(CH2CH2PPh2)3]. Crystal structures of the alkenyl complexes [(np3)CoC(CO2Et)=CH2]BPh 4·0.5THF and [(np3)NiCH=CHC(O)OEt]BPh4
Bianchini, Claudio,Innocenti, Paolo,Masi, Dante,Meli, Andrea,Sabat, Michal
, p. 72 - 78 (2008/10/08)
The hydride (np3)CoH (1) [np3 = N(CH2CH2PPh2)3] reacts with HC≡CCO2Et to yield the σ-alkenyl complex (np3)CoC(CO2Et)=CH2 (2) by insertion of the alkyne molecule into the Co-H bond. Addition of NaBPh4 in n-butyl alcohol to a tetrahydrofuran solution of 2 gives the Co(II) derivative [(np3)CoC-(CO2Et)=CH2]BPh 4·0.5THF (3). The crystal structure of 3 has been determined by standard X-ray methods. The compound crystallizes in the triclinic space group P1 with a = 17.937 (6) A?, b = 15.188 (5) A?, c = 12.916 (4) A7ring;, α = 87.00 (2)°, β = 101.37 (2)°, γ = 110.44 (2)°, and Z = 2. The structure was refined to an R factor of 0.088 (Rw = 0.087) using 3180 reflections with I > 3σ(I). The [(np3)CoC(CO2Et)=CH2]+ cation adopts the gem conformation with a Co-C distance of 1.91 (2) A?. Reaction of HC≡CCO2Et with the Ni(0) complex (np3)Ni (4) followed by NaBPh4 addition gives the β-carbethoxyvinyl complex [(np3)NiCH=CHC(O)-OEt]BPh4 (5), the structure of which has been established by an X-ray analysis. Compound 5 crystallizes in the monoclinic space group P21/a with a = 26.696 (7) A?, b = 14.729 (4) A?, c = 16.203 (4) A?, β = 105.50 (2)°, and Z = 4. The structure was refined to an R factor of 0.079 (Rw = 0.085) for 4933 reflections with I > 3σ(I). The β-carbethoxyvinyl group in the [(np3)NiCH=CHC(O)OEt]+ cation is chelated to Ni by its carbonyl oxygen atom and β-carbon atom forming a five-membered ring. The Ni-C and Ni-O bond distances are 1.878 (7) and 2.229 (5) A?, respectively. The reaction mechanisms for the formation of the σ-alkenyl complexes 2, 3, and 5 are briefly discussed.
