Choosing between Ti(II) and Ti(III): selective reduction of titanocene dichloride by elemental lanthanides
Guillaume Bousrez1,2, Dominique Harakat1, Sylviane Chevreux1,3
1Université de Reims Champagne Ardenne, CNRS UMR 7312, ICMR, URCATech, 51100 Reims, France.
Abstract:
The reduction of titanocene dichloride Cp2TiCl2 with lanthanide metals has led to the discovery of a surprising lanthanide effect: while with most lanthanides, a divalent [Cp2Ti] equivalent was obtained, the use of samarium or ytterbium only led to the reduction to trivalent [Cp2TiCl]-type complexes, including the structurally characterized heterobimetallic complex [Cp2Ti(μ-Cl)2SmCl2(THF)3]. These results were corroborated by reactivity studies (alkyne coupling and radical reactions), EPR spectroscopy and electrospray mass spectrometry, providing new insights into the reduction chemistry of lanthanide metals.
Related Concept Videos
Redox Titration: Other Oxidizing and Reducing Agents
Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation...
Acid Halides to Alcohols: LiAlH4 Reduction
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia
When dissolved in liquid ammonia, an alkali metal,...
Masking and Demasking Agents
There are many masking agents, such as cyanide, fluoride, triethanolamine, thiourea, and 2,3-bis(sulfanyl)propan-1-ol (formerly 2,3-dimercapto-1-propanol), with the masking agent chosen based on...
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction


