Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2021 Dec 20;27(71):17751-17760.
doi: 10.1002/chem.202102855. Epub 2021 Oct 15.

Take a "Snapshot" of New Syntheses, Reactions, and Characterizations from Unusual Unsaturated Ring Strained Group 4 Metallacycles

Uwe Rosenthal  1
Affiliations
Review

Take a "Snapshot" of New Syntheses, Reactions, and Characterizations from Unusual Unsaturated Ring Strained Group 4 Metallacycles

Uwe Rosenthal. Chemistry. .

Abstract

Recently published syntheses, reactions and characterizations of unusual unsaturated ring strained Group 4 metallocene metallacycles like metalla-cyclocumulenes, -cycloallenes and -cycloalkynes with different ring size are updated for the last three years. There exist for some of these metallacycles, depending on the ring size, 7-, 5- and 4-membered compounds. The new results for these metallacycles are summarized here and considered in addition to the former published results. Additionally, several compounds of this type were now characterized by new reactions. For a better understanding of these compounds, some spectroscopical methods as well as theoretical calculations were published. Despite of these all-C-metallacycles, only in some cases the syntheses and reactions for the corresponding hetero-metallacycles were published too. Examples for these metallaheterocyclic compounds will not be considered in this article. All these unusual ring strained compounds have a great potential for a lot of interesting synthetic applications in the future. Additionally, they are very interesting from the theoretical point of view.

Keywords: group 4 metals; organic syntheses; organometallic compounds; theoretical investigations; unusual metallacycles.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Examples for metalla‐cyclocumulenes, ‐cycloallenes and ‐cycloalkynes with different ring size.
Scheme 2
Scheme 2
Different mesomeric descriptions of 7‐membered metalla‐cyclocumulenes.
Scheme 3
Scheme 3
Equilibrium for dissociation and association of 7‐membered metalla‐cyclocumulenes.
Scheme 4
Scheme 4
Reactions of the 7‐membered metalla‐cyclocumulenes with benzophenone and acenaphthenequinone.
Scheme 5
Scheme 5
Reactions of the 7‐membered metalla‐cyclocumulenes with HCl.
Scheme 6
Scheme 6
Reduction of Cp’2ZrCl2 (Cp’=Cp and Cp*) by magnesium in the presence of H(Me3SiC≡C)C=C(SiMe3)−C(SiMe3)=C(C≡CSiMe3)H or H(Me3SiC≡C)C=C(SiMe3)−C(SiMe3)=C=C=C(SiMe3)H to different zirconabicycles.
Scheme 7
Scheme 7
Formation and reaction of a zirconocene [4]radialene of zirconocene.
Scheme 8
Scheme 8
Formation of 1‐metalla‐cyclopenta‐2,3‐dienes
Scheme 9
Scheme 9
Reactions of 5‐membered metalla‐cycloallene compounds with ketones and nitriles.
Scheme 10
Scheme 10
Reactions of 5‐membered metalla‐cycloallene compounds with carboxylate esters and isocyanates.
Scheme 11
Scheme 11
Insertion of ketones and reaction of the formed intermediates via transmetallation by copper salts with a subsequent addition of allyl halides to allylated products.
Scheme 12
Scheme 12
Reaction of rac‐(ebthi)TiCl2 with Li2(Me3Si−C=C=C−SiMe3) to rac‐(ebthi)Ti[−C(SiMe3)=C=C(SiMe3)−] (rac‐ebthi=rac‐1,2‐ethylene‐1,1’‐bis(η5‐tetrahydroindenyl)).
Scheme 13
Scheme 13
Twofold C−H activation of the propargylic positions of 3‐hexyne and the formation of a titanacyclopentyne.
Scheme 14
Scheme 14
Mesomeric description for 4‐membered titanacycloallenes unsaturated and ring strained four membered MC3.
Scheme 15
Scheme 15
Bonding situation of rac‐(ebthi)Ti[η2‐C(SiMe3)=C=C(SiMe3)−] as a singlet biradical of Ti(III) coupled with a monoanionic allene radical.
See this image and copyright information in PMC

References

    1. Selected Reviews:
    1. Ohff A., Pulst S., Lefeber C., Peulecke N., Arndt P., Burlakov V. V., Rosenthal U., Synlett 1996, 111–118;
    1. Rosenthal U., Burlakov V. V., Arndt P., Baumann W., Spannenberg A., Organometallics 2005, 24, 456–471;
    1. Rosenthal U., Burlakov V. V., Bach M. A., Beweries T., Chem. Soc. Rev. 2007, 36, 689–820; - PubMed
    1. Rosenthal U., Angew. Chem. 2008, 120, 5196–5199;
    2. Angew. Chem. Int. Ed. 2008, 47, 5118–5121; - PubMed

LinkOut - more resources