Octahedral metal carbonyls. XLV. Kinetics and mechanism of ligand exchange in tungsten carbonyl complexes containing chelating ligands bonding through nitrogen
✍ Scribed by Gerard R. Dobson; Ahmad Moradi-Araghi
- Book ID
- 104137670
- Publisher
- Elsevier Science
- Year
- 1978
- Tongue
- English
- Weight
- 638 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0020-1693
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✦ Synopsis
The kinetics and mechanism of the reaction of (tmen)W(CO), (tmen = N,N,N',N'-tetramethylethylenediamine) and (tmpa)W(COj4 (tmpa = N,N,N', N'-tetramethyl-1,3diaminopropane) with phosphines and phosphites (L) to afford L,W(CO), products have been investigated in detail. For both substrates, rate data support a mechanism involving two competing paths, one involving unimolecular, reversible ringopening, the other a concerted process involving an interchange of L and one end of the bidentate chelating ligand; the former path predominates. The results are compared to studies of analogous systems containing chelating sulfur ligands. Intermediates of the type cis-(?,'-tmpa)(L)W(CO), (I, = bicvclic phosphite) were identified. The nature o,f five-coordinate intermediates ,formed via ring-opening in (tmpaj-W(CO), was also studied. (Tmpa) W(CO), is a useful intermediate for the synthesis of (diolefin)W(C0)4 complexes; thus (norbornadiene) W(CO), was prepared in reasonable yield through reaction of (tmpa) W(CO), with norbornadiene in hydrocarbon solvent under mild conditions.