Phosphorus‐Stabilized Titanium Carbene Complexes: Synthesis,Reactivity and DFT Studies |
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| Authors: | Mathieu Lafage Dr. Hadrien Heuclin Dr. Xavier‐Frédéric Le Goff Dr. Nathalie Saffon‐Merceron Dr. Nicolas Mézailles |
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| Affiliation: | 1. Laboratoire “Hétérochimie Fondamentale et Appliquée”, Université Paul Sabatier, CNRS UMR 5069, 31062 Toulouse Cedex (France);2. Laboratoire “Hétéroéléments et coordination” Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France);3. Institut de Chimie de Toulouse ICT‐FR2599, Université Paul Sabatier, 31062 Toulouse Cedex (France) |
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| Abstract: | The synthesis of two novel titanium carbene complexes from the bis(thiophosphinoyl)methanediide geminal dianion 1 (SCS2?) is described. Dianion 1 reacts cleanly with 0.5 equivalents of [TiCl4(thf)2] to afford the bis‐carbene complex [(SCS)2Ti] ( 2 ) in 86 % yield. The mono‐carbene complex [(SCS)TiCl2(thf)] ( 3 ) can also be obtained by using an excess of [TiCl4(thf)2]. The structures of 2 and 3 are confirmed by X‐ray crystallography. A strong nucleophilic reactivity towards various electrophiles (ketones and aldehydes) is observed. The reaction of 3 with N,N′‐dicyclohexylcarbodiimide (DCC) and phenyl isocyanate leads to the formation of two novel diphosphinoketenimines 8 a and 8 b . The bis‐titanium guanidinate complex 9 is trapped as the by‐product of the reaction with DCC. The X‐ray crystal structures of 8 a and 9 are presented. The mechanism of the reaction between complex 3 and DCC is rationalized by DFT studies. |
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| Keywords: | carbene ligands density functional calculations geminal dianions reaction mechanisms titanium |
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