180400-79-7Relevant academic research and scientific papers
Synthesis and crystal structure of novel 1,3-heterobinuclear complexes with an unusual cyclic C4R3 bridging ligand
Fischer, Helmut,Leroux, Frédéric,Roth, Gerhard,Stumpf, Rüdiger
, p. 3723 - 3731 (1996)
Pentacarbonyl(dimethylvinylidene)chromium, [(CO)5Cr=C=CMe2] (1), reacts with the alkynyl complexes [Cp(CO)2FeC≡CR] (4a-e; R = nBu (a), Me (b), Ph (c), C6H4NO2-P (d), COOMe (e)), [Cp(CO){P(OMe)3}FeC≡CnBu] (6), [Cp(CO){PPh3}FeC≡CnBu] (8), and [Cp-(PEt3)NiC=CnBu] (19) by cycloaddition of the C≡C bond of the alkynyl complexes to the C=C bond of 1 to give [(CO)5Cr-C-CR-C(CMe2)-Fe(CO)2Cp] (5a-e), [(CO)5Cr-C-C-(nBu)-C(CMe2)-Fe(CO){P(OMe) 3}Cp] (7), [(CO)5Cr-C-C(nBu)-C(CMe2)-Fe(CO)-{PPh 3}Cp] (9), and [(CO)5Cr-C-C(nBu)-C(CMe2)-Ni(PEt 3)Cp] (20), respectively. The analogous reaction of [(CO)5Cr=C=C(CH2)5] (2) with 4a and 6 affords complexes with a spirocyclic bridging ligand: [(CO)5Cr-C-C(nBu)-C{C(CH2) 5}-Fe(CO)2Cp] (10) and [(CO)5Cr-C-C(nBu)-C{C(CH2) 5}-Fe(CO){P(OMe)3}Cp] (11). Cycloaddition of 4a to [(CO)5Cr=C=CPh2] (3) yields [(CO)5Cr-C-C(nBu)-C(CPh2)-Fe(CO)2Cp] (12). The spectroscopic data of these novel 1,3-heterobinuclear complexes indicate the delocalized π-system Cr-C-C-C-M (M = Fe, Ni). X-ray structural analyses of the compounds 5e, 10, and 11 reveal a butterfly conformation. The puckering angle of the four-membered ring is 160.0° (5e), 143.9° (10), and 144.9° (11). Both C(sp2)-C(sp2) bonds are almost equal in length. All complexes exhibit negative solvatochromic behavior. The extent of the solvatochromic effect is strongly influenced by the substituents at C-2 and C-4 of the ring.
