Coupling reactions of ynamines. Syntheses, structural characterization and electrochemistry of some nido and closo ferracyclopentadiene complexes

Article abstract of DOI:10.1016/0022-328X(92)80193-2

The reaction of > (1) with ynamines RC<*>CNEt2 (R = Me, C3H5, or CH2Ph) at 20 deg C yielded dinuclear ferracyclopentadiene complexes > (R = Me (2), R = CH2Ph (3), R = C3H5 (4)).Complex 5, >, was obtained directly from the reaction of C3H5C<*>CNEt2 with .All complexes were characterized by a combination of microanalytical and spectroscopic techniques.The molecular structure of 4 was determined X-ray crystallographically: triclinic, P<*>, a = 8.820(2) Angstroem, b = 9.261(2) Angstroem, c = 18.470(2) Angstroem, α = 89.40(1) deg, β = 81.81(1) deg, γ = 70.23(2) deg, R_w = 0.0406 for 2580 reflections.The nido complexes 4 and 5 transformed to the closo tripledecker compounds > (R = Ph (6); R = C3H5 (7)) by an excess of in refluxing hexane.Both complexes were characterized by IR, 1H NMR, mass spectra and chemical analysis.The X-ray structure of 6 was carried out: monoclinic, P2₁/c, a = 14.900(3), b = 11.149(2), c = 18.453(4) Angstroem, β = 91.14(2) deg, R_w = 0.0414 for 2304 reflections.Only one isomer could be isolated for the nido compounds.The nido-closo transformation did not modify the coupling within the butadiene moiety.Electrochemistry of the nido and closo complexes is reported.The closo compounds showed two reversible one-electron reduction waves whereas the nido species were completely irreversibly reduced.