Diarylallenylidene(pentacarbonyl)-chromium and-tungsten complexes, (CO)sM=C=C=CR 2 (M = W (1), Cr (2», react with amines, imines and hydrazines by addition of the nitrogen nucleophile to the C" allenylidene atom. With NEt3 the adduct formation is reversible. With secondary and primary amines, imines and hydrazines, the initially formed N-ylide complexes react readily further to give carbene, azetidinylidene and nitrile complexes, respectively. For example the reaction of (a) 1 and 2 with HNEt2 or HzNPh gives alkenyl(amino}carbene complexes, (CO)sM=C[C(H)=CR z ] NR z (3-5); (b) of 1 and 2 with HN=CR'2 gives alkenyl(al-kylideneamino}carbene complexes, (CO)sM=C[C(H)=CR z ] [N=CR z ] (6,7); (c) of 1 with CPr)N=C(Ph)H the azetidinylidene complex 9; (d) of 1 with 1,2-disubstituted hydrazines such as H(Me)NN(R)H (R = Me, Ph) alkenyl(hydrazino)carbene complexes, (CO)sW=C[C(H)=CR 2 ] [N(Me)N(R)H] (11) and (e) of 1 with H z NNR 1 R 2 (R 1 = R2 = H, Me; Rl = H, R2 = Ph) alkenyl(amino)carbene complexes (13) and/or acrylnitrile complexes, (CO)sW[N = C-C(H)=CR 2 ] (12). The structures of representative examples of 6, 11 and 12 were established by X-ray analyses. Zusammenfassung Diarylallenyliden(pentacarbonyl)chrom-und-wolfram-Komplexe, (CO)sM=C=C=CR 2 (M = W (1), Cr (2», reagieren mit Aminen, Iminen and Hydrazinen unter Addition des Stickstoffnukleophils an das C,,-A1lenylidenatom. Die Adduktbildung ist mit NEt3 reversibel. Mit sekundaren und primaren Aminen, Iminen und Hydrazinen reagieren die zunachst gebildeten N-Ylidkomplexe rasch weiter zu Carben-, Azetidinyliden-bzw. Nitril-Komplexen. So erhalt man z. B. bei der Reaktion von (a) 1 und 2 mit HNEt2 oder H 2 NPh Alkenyl(amino}carben-Komplexe, (CO)sM=C[C(H)=CR 2 ]NR z (3-5); (b) von 1 und 2 mit HN=CR z A1kenyl(al-kylidenamino}carben-Komplexe, (CO)sM=C[C(H)=CR 2 ] [N=CR z ] (6, 7); (c) von 1 mit (ipr)N=C(Ph)H den Azetidinyliden-Komplex 9; (d) von 1 mit 1,2-disubstituierten Hydrazinen wie H(Me)NN(R)H (R = Me, Ph) Alkenyl(hydrazino)carben-Komplexe, (CO)s W=C-[C(H)=CR 2 ] [NMeN(R)H] (11); und (e) von 1 mit H2NNRIR2 (R 1 = R2 = H, Me; Rl = H, R2 = Ph) A1kenyl(amino)carben-Komplexe (13) und/oder Acrylnitril-Komplexe, (CO)sW[N=C-C(H)=CR 2 ] (12). Die Strukturen reprasentativer Beispiele von 6, 11 und 12 wurden durch Riintgenstrukturanalysen gesichert.

The reaction of the diarylallenylidene complexes [(CO)5MCCC(C6H4R-p)2] (M = Cr (1), W (2); R = H (a), Me (b), OMe (c), NMe2 (d)) with the ynamines MeC⋮CNEt2 and PhC⋮CNEt2 affords two products:  alkenylallenylidene (3, 5) and cyclobutenylidene complexes (4, 6). The alkenylallenylidene complexes [(CO)5MCCC(NEt2)C(R‘)C(C6H4R-p)2] (R‘ = Me, M = Cr (3), W (5), R = H (a), Me (b), OMe (c), NMe2 (d); R‘ = Ph, M = Cr (3), R = OMe (e), NMe2 (f)) are formed via cycloaddition of the C⋮C bond of the ynamine to the C2C3 bond of 1 and 2, respectively, and subsequent cycloreversion. The cyclobutenylidene = Me, M = Cr (4), W (6), R = H (a), Me (b), OMe (c), NMe2 (d); R‘ = Ph, M = Cr (4), R = OMe (e), NMe2 (f)) are formed by cycloaddition of the ynamines to the C1C2 bond of 1 and 2. The compounds 3, 4a−c, 5, and 6a−c are stable at room temperature. In contrast, 4d−f and 6d decompose on contact with air, light, or silica. Complex 3d was characterized by an X-ray structural analysis. The product ratios 3/4 and 5/6 strongly depend on the solvent and the substitution pattern of both the allenylidene complexes 1 and 2 and the ynamine. In general, decreasing polarity of the solvent increasingly favors formation of cyclobutenylidene complexes. The solvent dependence indicates that the transition state for the formation of 4 and 6 is significantly less polar than that for the formation of 3 and 5. The ratios 3/4 and 5/6 increase in the series a < b < c < d. Kinetic measurements of the reaction of 1c,d with the ynamines MeC⋮CNEt2 and PhC⋮CNEt2 reveal that the complex pairs 3,4 and 5,6 are formed in parallel pathways with an associative rate-determining step for each. The reactions follow second-order kinetics, first-order in the concentrations of the allenylidene complexes 1,2 and of the ynamines. The activation enthalpies ΔH ⧧ are small, and the activation entropies ΔS ⧧ are strongly negative. ΔS ⧧ is more negative for the formation of the alkenylallenylidene complexes than for the formation of the cyclobutenylidene complexes.

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