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Amino-substituted butatrienes : Unusual η<sup>1</sup> ligands formed by an unusual reaction

Amino-substituted butatrienes : Unusual η1 ligands formed by an unusual reaction

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REICHMANN, Bernhard, Matthias DREXLER, Bernhard WEIBERT, Normen SZESNI, Tobias STRITTMATTER, Helmut FISCHER, 2011. Amino-substituted butatrienes : Unusual η1 ligands formed by an unusual reaction. In: Organometallics. 30(5), pp. 1215-1223. ISSN 0276-7333

@article{Reichmann2011Amino-19739, title={Amino-substituted butatrienes : Unusual η1 ligands formed by an unusual reaction}, year={2011}, doi={10.1021/om101163j}, number={5}, volume={30}, issn={0276-7333}, journal={Organometallics}, pages={1215--1223}, author={Reichmann, Bernhard and Drexler, Matthias and Weibert, Bernhard and Szesni, Normen and Strittmatter, Tobias and Fischer, Helmut} }

Strittmatter, Tobias Reichmann, Bernhard The reaction of the bis(amino)allenylidene complex [(CO)<sub>5</sub>W═C═C═C(NMe<sub>2</sub>)<sub>2</sub>] with diethyldiazomethane yields two products, a cyclic carbene complex (2) by 1,2-addition of Et<sub>2</sub>C−N<sub>2</sub> to the C<sub>α</sub>−C<sub>β</sub> bond of the allenylidene ligand and the η<sup>1</sup>-butatriene complex [(CO)<sub>5</sub>W{C[C(NMe<sub>2</sub>)<sub>2</sub>]═C═CEt<sub>2</sub>}] (3). Complex 2 slowly eliminates N<sub>2</sub> and rearranges into 3. In contrast, only η<sup>1</sup>-butatriene complexes, [(CO)<sub>5</sub>M{C[C(NMe<sub>2</sub>)XR]═C═C(R′)<sub>2</sub>}], are isolated from the reaction of diazoalkanes (R′)<sub>2</sub>C−N<sub>2</sub> (R′ = Me, Et, <sup>n</sup>Pr) with alkoxy(amino)allenylidene complexes [(CO)<sub>5</sub>M═C═C═C(NMe<sub>2</sub>)OR] (M = Cr, W; R = Me, Et, (−)-menthyl) or with the (alkylthio)(amino)allenylidene complex [(CO)<sub>5</sub>W═C═C═C(NMe<sub>2</sub>)S<sup>n</sup>Pr]. These new η<sup>1</sup>-butatriene complexes are related to C<sub>α</sub> phosphine adducts of allenylidene complexes such as [(CO)<sub>5</sub>W{C(PMe<sub>3</sub>)═C═C(NMe<sub>2</sub>)Ph}] (17) and might be regarded as C<sub>α</sub> carbene adducts. However, the PMe<sub>3</sub> substituent in 17 is not replaced when 17 is treated with an N-heterocyclic carbene. Vice versa, the “carbene” substituent “C(NMe<sub>2</sub>)OEt” in the η<sup>1</sup>-butatriene complex [(CO)<sub>5</sub>Cr{C[C(NMe<sub>2</sub>)OEt]═C═CEt<sub>2</sub>}] is not replaceable by PMe<sub>3</sub>. Free N-heterocyclic carbenes do not add to the C<sub>α</sub> atom of the allenylidene complex [(CO)<sub>5</sub>W═C═C═C(C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-p)<sub>2</sub>] but instead to the C<sub>γ</sub> atom, giving the dipolar neutral alkynyl complexes [(CO)<sub>5</sub>W−C≡CC(C<sub>6</sub>H<sub>4</sub>NMe<sub>2</sub>-p)<sub>2</sub>L] (L = SIMe, SIMes). DFT calculations on the reaction mechanism indicate that a cyclic carbene complex and two isomeric η<sup>2</sup>-butatriene complexes are intermediates in the reaction pathway to form η<sup>1</sup>-butatriene complexes. The structure of two representative examples of η<sup>1</sup>-butatriene complexes and of one C<sub>γ</sub> carbene adduct has been established by X-ray structure analyses. Strittmatter, Tobias Fischer, Helmut eng Fischer, Helmut Amino-substituted butatrienes : Unusual η<sup>1</sup> ligands formed by an unusual reaction Drexler, Matthias Weibert, Bernhard Szesni, Normen Publ. in: Organometallics ; 30 (2011), 5. - pp. 1215-1223 2011 2012-10-31T23:25:04Z 2012-07-20T19:17:52Z Weibert, Bernhard deposit-license Szesni, Normen Reichmann, Bernhard Drexler, Matthias

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