Synthetic access to half-sandwich manganese C4 cumulenic complexes

Koushik Venkatesan, Olivier Blacque, Thomas Fox, Montserrat Alfonso, Helmut W. Schmalle, Heinz Berke*

*Corresponding author for this work

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The vinylalkynyl complexes Mn(C5H4R′) (R″2PCH2CH2PR″2)(=C= CSnPh3C≡CSnPh3) (5, 6) were obtained in good yields by treatment of Mn(C5H4R′)(η6- cycloheptatriene) (R′ = H (1a), Me (1b)) with 1 equiv of Ph 3SnC≡CC≡CSnPh3 and R″2PCH2CH2PR″2 (R″ = CH3 (dmpe), C2H5 (depe)). The theoretically characterized (DFT) C4 cumulenic species Mn(C5H 4R′)(R″2PCH2CH 2PR″2){=C=C=C=C(SnPh3)2} (7, 8) were obtained by photolysis of the tinsubstituted vinylalkynyl complexes 5 and 6. Subsequently 7 and 8 could be converted into the parent cumulenic species Mn(C5H4R′)(R″2PCH 2CH2PR″2){=C=C=C=C(H)2} (9, 10) by reacting complexes 7 and 8 with TBAF (5% H2O) at -40 °C. The difference in the thermodynamic stabilities between the complexes 7 and 8 and complexes 9 and 10 was traced by DFT calculations using Mn(C 5H5)(dHpe){=C=C=C=C(SnMe3)2} (4-H) and Mn(C5H5)(dHpe){=C=C=C=CH2} (9-H) as model complexes. Treatment of the vinylalkynyl complex with an excess of MeOH led to the formation of a dinuclear complex with a C8 chain between two manganese centers. The cumulenic complexes and the vinylalkynyl complexes were characterized by NMR and vibrational spectroscopy and elemental analyses. An X-ray diffraction study has been performed on complex 4b.

Original languageEnglish
Pages (from-to)4661-4671
Number of pages11
JournalOrganometallics
Volume23
Issue number20
DOIs
Publication statusPublished - 27 Sep 2004
Externally publishedYes

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