Hydrazinocarben-Metallkomplexe - Synthese aus Allenylidenkomplexen und Hydrazinen, Umlagerung und Cyclisierung

Article abstract of DOI:10.1016/0022-328X(94)05187-G

The diarylallenylidene pentacarbonyl complexes (CO)5M=C=C=C(C6H4NMe2-p)2 (M = W (1), Cr (2)) add 1,2-disubstituted hydrazines RHN-HNR to form alkenyl hydrazino carbene complexes (CO)5M=C(C(H)=C(C6H4NMe2-p)2)NR-N(H)R (M = W, R = Bn (3b), ⁱPr (3c), ^cHex (3d); M = Cr, R = Me (4a), ⁱPr (4b)) in good yield. 3c and 4b are formed selectively as E-conformers (E arrangement of N_βHR and (CO)5M with respect to the C(carbene)-N_α bond).In contrast, all other derivatives of 3 and 4 are obtained as a mixture of E/Z-isomers.On heating, E-3a and E-3b rearrange to give the acrylamidine complexes (CO)5WNR=C(NHR)C(H)=C(C6H4NMe2-p)2 (R = Me (5a), Bn (5b)).The structure of complex 5b was established by X-ray analysis.Acid-catalyzed, the alkenyl hydrazino carbene complexes E-3a, E-3b and 3c are transformed by intramolecular cyclization into the pyrazolidinylidene complexes (R = Me (6a), Bn (6b), ⁱPr (6c)). Keywords: Alkenylhydrazinocarbene complexes; X-ray structure analysis; Rearrangement; Chromium; Tungsten