Hydrazinocarben-Metallkomplexe—synthese aus allenylidenkomplexen und hydrazinen, umlagerung und cyclisierung

doi:10.1016/0022-328X(94)05187-G

Journal of Organometallic Chemistry

Volume 490, Issues 1–2, 22 March 1995, Pages 229-237

https://doi.org/10.1016/0022-328X(94)05187-G Get rights and content

Abstract

The diarylallenylidene pentacarbonyl complexes (CO)₅M=C=C=C(C₆H₄NMe₂-p)₂ (M = W (1), Cr (2)) add 1,2,-disubstituted hydrazines RNH-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)₅W-NR=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)).

Zusammenfassung

Die Diarylallenyliden(pentacarbonyl)komplexe (CO)₅M=C=C=C(C₆H₄NMe₂-p)₂ (M = W (1), Cr (2)) addieren 1,2-disbustituierte Hydrazine RNH-HNR in guten Ausbeuten zu Alkenylhydrazinocarbenkomplexen (CO)₅M=C(C(H)=C(C₆H₄NMe₂p)₂) NR-N(H)R (M = W, R = Bn (3b), ⁱPr (3c), ^cHex (3d); M = Cr, R =Me(4a), ⁱPr (4b)). 3c und 4b entstehen hierbei selektiv in der E-Konformation (E-Anordnung von N_βHR und (CO)₅M bezülich der C(Carben)-N_α-Bindung). Alle anderen Derivate von 3 und 4 werden dagegen als E/Z-Isomerengemisch gebildet. E-3a und E-3b lagern sich beim Erwärmen in die Acrylamidinkomplexe (CO)₅W-NR=C(NHR)C(H)=C(C₆H₄NMe₂-p)₂ (R = Me (5a), Bn (5b)) um. Die Struktur von 5b wurde anhand einer Röntgenstrukturanalyse gesichert. Säurekatalysiert cyclisieren die Alkenylhydrazinocarbenkomplexe E-3a, E-3b und 3c zu den Pyrazolidinylidenkomplexen

(R = Me (6b), ⁱPr (6c)).

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The reaction of pentacarbonyl(pyrazolin-3-ylidene)chromium complexes,
(2a–c) (R = Ph (a), C₆H₄NMe₂-4 (b); (C₅H₄)FeCp (c)), with [AuCl(SMe₂)], H[AuCl₄], [PdCl₂(NCPh)₂] and [PtCl₂(NCPh)₂] gives, by transfer of the heterocyclic carbene ligand, new chloro pyrazolin-3-ylidene complexes of gold(I) and gold(III), dichloro bis(pyrazolin-3-ylidene) palladium and dichloro bis(pyrazolin-3-ylidene) platinum in high yield. The chloride ligand in
(Fc = (C₅H₄)FeCp) is readily displaced by trifluoroacetate. The analogous substitution of iodide for the chloride ligands in
(M = Pd, Pt) give the corresponding diiodo complexes although in a much slower reaction. In contrast, the reaction of silver trifluoroacetate with
affords a binuclear Pd–Ag complex containing two pyrazolin-3-ylidene and three trifluoroacetate ligands two of whom occupy bridging positions between Pd and Ag. The reactions of the pyrazolidin-3-ylidene complex
(R = C₆H₄NMe₂-4) with [AuCl(SMe₂)] and [PdCl₂(NCPh)₂] yield chloro pyrazolidin-3-ylidene gold and dichloro bis(pyrazolidin-3-ylidene) palladium complexes. The related dichloro bis(tetrahydropyrimidin-4-ylidene) palladium complex is formed in the reaction of
with the palladium complex [PdCl₂(NCPh)₂]. The solid-state structures of several of these heterocyclic carbene complexes including the structure of the binuclear Pd–Ag complex are established by X-ray structure analyses.
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Heterocyclic carbene complexes are accessible from π-donor-substituted allenylidene complexes, [(CO)₅CrCCC(NMe₂)Ph] (1) and [(CO)₅CrCCC(O-endo-Bornyl)OEt] (4), and various dinucleophiles by 1,2,3-diheterocyclization. The reaction of 1 with 1,2-dimethylhydrazine gives the 1,2-dimethylpyrazolylidene complex
(2) in high yield in addition to small amounts of the α,β-unsaturated carbene complex [(CO)₅CrC(NMe₂)–C(H)C(NMe₂)Ph] (3). The analogous reaction of 4 with 1,2-dimethylhydrazine affords the 1,2-dimethylpyrazolylidene complex
(5) and, via displacement of the C_γ-bound ethoxy substituent, the hydrazinoallenylidene complex [(CO)₅CrCCC(O-endo-Bornyl){NMe-N(H)Me}] (6). Treatment of 6 with catalytic amounts of acids induces cyclization to 5. On addition of 1,1-dimethylhydrazine to 1 the zwitterionic pyrazolium-5-ylidene complex
(7) is formed. The reaction of 1 with 1,2-diaminocyclohexane affords a octahydro-benzo[1,4]diazepinylidene complex (10) and, via intermolecular substitution, a binuclear bisallenylidene complex (11). Thiazepinylidene complexes (12–14), containing 7-membered N/S-heterocyclic carbene ligands, are formed highly selectively in the reaction of 1 with 2-aminoethanethiol or related cysteine derivatives by a substitution/cyclization sequence. The analogous reaction of 1 with homocysteine methylester yields a thiazocanylidene complex (15). All new heterocyclic carbene ligands are strong donors exhibiting σ-donor/π-acceptor ratios similar to those of the known imidazolylidene complexes. On photolysis of 2 and 12 in the presence of triphenylphosphine, the corresponding cis-carbene tetracarbonyl triphenylphosphine complexes (16 and 17) are formed. The solid state structure of complexes 2, 7, 14, 15, and 16 is established by X-ray structural analysis.
A convenient route to six-membered heterocyclic carbene complexes: Reactions of aminoallenylidene complexes with 1,3-bidentate nucleophiles
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Pentacarbonyl dimethylamino(methoxy)allenylidene complexes of chromium and tungsten, [(CO)₅MCCC(NMe₂)OMe] (M = Cr (1a), W (1b)), react with 1,3-bidentate nucleophiles such as amidines and guanidine, H₂N–C(NH)R (R = Ph, C₆H₄NH₂-4, C₆H₄NO₂-3, NH₂), by displacing the methoxy substituent to give exclusively dimethylamino(imino)-allenylidene complexes, [(CO)₅MCCC{NC(NH₂)R}NMe₂] (2a–5a, 2b). Treatment of the chromium complexes 2a–5a with catalytic amounts of hydrochloric acid or HBF₄ gives rise to an intramolecular cyclization. Addition of the terminal NH₂ substituent to the C_α–C_β bond of the allenylidene chain affords pyrimidinylidene complexes 6–9 in high yield. In contrast to the chromium complexes 2a–5a, the corresponding tungsten complex 2b could not be induced to cyclize due to the lower electrophilicity of the α-carbon atom in 2b. The dimethylamino(phenyl)allenylidene complex [(CO)₅CrCCC(NMe₂)Ph] (10) reacts with benzamidine or guanidine similarly to 1a. However, the second reaction step – cyclization to give pyrimidinylidene complexes – proceeds much faster. Therefore, the formation of an imino(phenyl)allenylidene complex as an intermediate is established only by IR spectroscopy. The analogous reaction of 10 with 3-amino-5-methylpyrazole affords, via a formal [3+3]-cycloaddition, a pyrazolo[1,5a]pyrimidinylidene complex 13. Compound 13 is obtained as two isomers differing in the relative position of the N-bound proton (1H or 4H). The related reaction of 10 with thioacetamide yields a thiazinylidene complex and additionally an alkenyl(amino)carbene complex.
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Pentacarbonyl dimethylamino(methoxy)allenylidene tungsten, [(CO)₅WCCC(OMe)NMe₂] (1b), reacts with one equivalent of primary amines, H₂NR, by selectively replacing the methoxy group to give dimethylamino(amino)allenylidene complexes, [(CO)₅WCCC(NHR)NMe₂]. When the amine is used in excess both terminal groups, OMe as well as NMe₂, are replaced by the primary amino group giving [(CO)₅WCCC(NHR)₂ ]. The NHR substituent in these complexes may be modified by deprotonation with LDA followed by alkylation. The replacement of the methoxy group in 1b by a secondary amino group, NR₂, can be achieved by a stepwise process. Addition of Li[NR₂] to the C_γ atom of 1b affords an alkynyl tungstate. Subsequent OMe⁻ elimination induced by TMS-Cl/SiO₂ yields the allenylidene complexes [(CO)₅WCCC(NR₂)NMe₂]. When bidentate diamines are used instead of monoamines both substituents, OMe and NMe₂, are replaced and allenylidene complexes are formed in which C_γ constitutes part of a 5-, 6-, or 7-membered heterocycle. The reaction of [(CO)₅CrCCC(OMe)NMe₂] (1a) with diethylene triamine affords an allenylidene complex with a heterocyclic endgroup carrying a dangling CH₂CH₂NH₂ substituent. All reactions follow a strict regioselective attack of the nucleophile at C_γ and proceed with good to excellent yields. The addition of N–H to the C_αC_β bond is not observed. By applying either one of these routes nearly any substitution pattern in bis(amino)allenylidene complex can be realized.

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Regular paperHydrazinocarben-Metallkomplexe—synthese aus allenylidenkomplexen und hydrazinen, umlagerung und cyclisierung

Abstract

Zusammenfassung

Chem. Ber.

J. Organomet. Chem.

Organometallics

Z. Naturforsch., Teil B

Angew. Chem.

Angew. Chem., Int. Edn, Engl.

Angew. Chem.

Angew. Chem. Int. Edn. Engl.

Angew. Chem.

Angew. Chem., Int. Edn. Engl.

Chem. Rev.

Z. Naturforsch., Teil B

J. Organomet. Chem.

Organometallics

J. Organomet. Chem.

Regular paper
Hydrazinocarben-Metallkomplexe—synthese aus allenylidenkomplexen und hydrazinen, umlagerung und cyclisierung