A heterobimetallic complex featuring a Ti-Co multiple bond and its application to the reductive coupling of ketones to alkenes

• Published in: Chemical science (Cambridge) Vol. 6; no. 3; pp. 2044 - 2049
• Main Authors: Wu, Bing, Bezpalko, Mark W, Foxman, Bruce M, Thomas, Christine M
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 01-03-2015
• Subjects: Alkenes; Bimetals; Bonding; Cobalt; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ketones; Ligands; MATERIALS SCIENCE; Titanium; Transition metals
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c4sc03772c

To explore metal-metal multiple bonds between first row transition metals, Ti/Co complexes supported by two phosphinoamide ligands have been synthesized and characterized. The Ti metalloligand Cl
Ti(XylNP
Pr
)
(
) was treated with CoI
under reducing conditions, permitting isolation of the Ti/Co complex [(μ-Cl)Ti(XylNP
Pr
)
CoI]
(
). One electron reduction of complex
affords ClTi(XylNP
Pr
)
CoPMe
(
), which features a metal-metal triple bond and an unprecedentedly short Ti-Co distance of 2.0236(9) Å. This complex is shown to promote the McMurry coupling reaction of aryl ketones into alkenes, with concomitant formation of the tetranuclear complex [Ti(μ
-O)(NXylP
Pr
)
CoI]
(
). A cooperative mechanism involving bimetallic C[double bond, length as m-dash]O bond activation and a cobalt carbene intermediate is proposed.