Syntheses of molybdenum(II) and molybdenum(IV) complexes bearing tethered homoallylic phosphines

Citation
Cw. Rodrigues et al., Syntheses of molybdenum(II) and molybdenum(IV) complexes bearing tethered homoallylic phosphines, ORGANOMETAL, 20(9), 2001, pp. 1825-1831
Citations number
40
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
ORGANOMETALLICS
ISSN journal
0276-7333 → ACNP
Volume
20
Issue
9
Year of publication
2001
Pages
1825 - 1831
Database
ISI
SICI code
0276-7333(20010430)20:9<1825:SOMAMC>2.0.ZU;2-L
Abstract
Photolysis of [CpMo(CO)(3)Cl] in the presence of 2-(1-propenyl)phenyldiphen ylphosphane (PP, cis/trans mixture) yields the complex [CpMo(CO)Cl(PP)], 2, with an olefin ligand tethered to a phosphorus donor atom. A trans configu ration of the substituents at the olefinic unit is thermodynamically prefer red, so that the corresponding complex 2(t) can be isolated in isomerically pure form under certain conditions. However, the cis-olefin complex 2(e) h as been characterized in its mixture with 2(t), too. Treatment of 2(t) with HNMe2 leads to the intramolecular elimination of HCl under formation of th e compound [CpMo(CO)(CH2-CHCHC6H4PPh2)], 3, bearing a chelating pi -allyl/P Ph2 ligand. When a CH2Cl2 solution of 3 is photolyzed in the presence of N2 O, the CO ligand is replaced by two chloride ligands, i.e., the Mo center i s oxidized to the oxidation state +IV. The resulting complex [CpMoCl2(CH2-C HCHC6H4PPh2)], 4, is one of the rare examples, where a soft allyl ligand is bound to a metal center in a comparatively high oxidation state. However, probably due to the chelate effect, the Mo-allyl bond is remarkably stable. All compounds 2-4 have been investigated by means of single-crystal X-ray diffraction, and their crystal structures are discussed.