1398388-76-5Relevant academic research and scientific papers
Reactions of 7,7,8,8-tetracyanoquinodimethane with poly-ynyl ruthenium and iron complexes
Bruce, Michael I.,Burgun, Alexandre,Grelaud, Guillaume,Lapinte, Claude,Parker, Christian R.,Roisnel, Thierry,Skelton, Brian W.,Zaitseva, Natasha N.
, p. 6623 - 6634 (2012/11/13)
The reaction of tetracyanoquinodimethane (TCNQ) with Ru(C≡CC≡ CH)(dppe)Cp* (5) at the outer (from Ru) C≡C triple bond gives η1-(butadienyl)ethynyl Ru{C≡CC[CH=C(CN)2]=C 6H4=C(CN)2}(dppe)Cp (8), which reacts with a second equivalent of diynyl-Ru complex to give {Ru(dppe)Cp*}{C≡CC[= C6H4=C(CN)2]CH=CHC[=C(CN)2] C≡C}{Ru(dppe)Cp*} (9). The Ph-substituted complexes M{C≡CC≡CPh}(dppe)Cp* (M = Fe 6-Fe, Ru 6-Ru) and Ru{(C≡C)3Ph}(PPh3)2Cp (7) react with TCNQ to give the η1-(butadienyl)ethynyls M{C≡CC[CPh=C(CN) 2]=C6H4=C(CN)2}(dppe)Cp (10-Fe, 10-Ru) and Ru{C≡CC[C(C≡CPh)=C(CN)2]=C6H 4=C(CN)2}(PPh3)2Cp (11), respectively. Single-crystal X-ray diffraction molecular structure determinations for 8-11 have been carried out. In the Fe series, we suggest that the initial step of the mechanism involves electron transfer to form the [TCNQ]-? salt of the diynyl-iron cation, followed by C-C bond formation to give a zwitterionic intermediate. Isolated products can be rationalized by further reaction involving [2 + 2]-cycloaddition of one of the C=C(CN)2 groups of TCNQ to a C≡C triple bond of the metal poly-ynyl complex and a subsequent ring-opening reaction of the resulting (unobserved) cyclobutenyl intermediate. On the basis of X-ray diffraction data, redox potential determinations, and 57Fe Moessbauer and UV-vis spectroscopies, the electronic structures of the new compounds contain significant contributions from polarized mesomers involving charge transfer from the electron-rich metal-ligand fragment to the cyanocarbon ligand via the conjugated unsaturated carbon linker.
