Application of Trianionic Pincer Ligands to Reactions Involving Group VI Alkylidynes, Metal-Metal Multiple Bonds, and Group IV Amides
Abstract
In an effort to isolate a pincer-support tungsten alkylidyne, several new tungsten alkylidenes and a ditungsten compound have been isolated, supported by the previously reported OCO3- pincer ligand [3,3 -di-tert-butyl-2,2 -di-(hydroxy-kappaO)-1,1 :3 ,1 -terphenyl-2 -yl-kappaC2 ] (tBuOCO 1). When the tBuOCO ligand precursor is treated with W(OAr)2(CH2(CH3)3)- (aC(CH3)3) (OAr= 2,6-diisopropylphenoxide) in benzene, the alkylidene complex [tBuOCO]- W(=CH(CH3)3)(O-2,6-iPr2-C6H3) (3) results and was characterized by a combination of one and two dimensional NMR spectroscopy, single-crystal X-ray crystallography, and combustion analysis. To aid in the final abstraction, W(CH2(CH3)3)3(aC(CH3)3) was next combined with 1, but the reaction resulted in a complicated mixture of products. From this mixture, two closely related structural isomers of the form {[tBuOCO](CH3)3CCH=}W( -tBuOCHO)W- {=CHC(CH3)3[tBuOCO]} (4 and 5) were isolated. This bridged, dinuclear complex was analyzed by single-crystal X-ray crystallography. Finally, the reaction of (NMe2)3WaW(NMe2)3 with two equivalents of 1 results first in [tBuOCHO](NMe2)WaW(NMe2)[tBuOCHO] (7) and after prolonged heating, [tBuOCHO]W(mu-NMe2)2(mu-O)W[tBuOCHO] (8). These complexes were analyzed by a combination of NMR spectroscopy, single-crystal X-ray crystallography, and combustion analysis. The exact mechanism of formation for 8 is not yet know, but it potentially represents a rare example of the oxidative addition of water to an early transition metal.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2008
- Accession Number
- ADA486094
Entities
People
- Andrew J Peloquin
Organizations
- University of Florida