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Synthesis and Reactions of Complexes of 1,3-Bis(diphenylphosphino)-2-methylallyl with Molybdenum or Tungsten Tetracarbonyls

DOI: 10.1039/DT9910003303

Source and publish data:

Journal of the Chemical Society, Dalton Transactions p. 3303 - 3310 (1991)

Update date:2022-08-05

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Authors:

Shaw, Bernard L.Shaw, Bernard L.

Vessey, Jonathan D.Vessey, Jonathan D.

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Article abstract of DOI:10.1039/DT9910003303

Treatment of molybdenum or tungsten hexacarbonyls with the diphosphine CH2=C(CH2PPh2)2 gives complexes (CO)4> (M = Mo, 3a; or W, 3b).Either of these complexes with sodium ethoxide in boiling ethanol exhibits prototropic rearrangement to give (CO)4> (M = Mo, 4a; or W, 4b).Treatment of either complexes 3 or 4 with strong bases such as methyllithium, lithium 2,2,6,6-tetramethylpiperidide or lithium bis(trimethylsilyl)amide gave bright orange solutions of the symmetrical 1,3-bis(diphenylphosphino)-2-methylallylmetal tetracarbonyl anions (CO)4>- 5.The molybdenum complex 5a, when treated with D2O, gave 6, which was shown to be a monodeuterio-complex by 2H, 1H and 13C NMR spectroscopy.Both the 31P-<1H> and the 13C-<1H> NMR spectra of this compound showed secondary isotope effects and the 13C-<1H> spectrum showed that there was no plane of symmetry, whereas with the corresponding perhydro complex 4a, there is such a plane (going through the Mo and the two P).The carbanions 5 react with electrophiles such as MeI, SiMe3Cl, EtI, allyl bromide, PhCH2Br or PPh2Cl to give substitution products (R'= Me, 7; SiMe3, 8; Et, 9; CH2=CHCH2, 10; CH2Ph, 11, or PPh2, 13); these complexes were fully characterised.Treatment of 7a (M = Mo) with LiMe and then an equivalent amount of methanol, followed by more LiMe and methanol, gave the isomerised product 12.When a solution of complex 13a (M = Mo) was heated in toluene the tricarbonyl (CO)3> 14a, in which all three phosphoruses are co-ordinated, was formed; similarly the corrsponding tungsten complex 13b, when heated in decane gave (CO)3> 14b.Proton, 2H, 13C and 31P NMR data, infrared <ν(C<*>O)> and some mass spectral data are given and discussed.

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Products guided by the article

Product name:Mo((C6H5)2PCHC(CH3)CH(P(C6H5)2)P(C6H5)2)(CO)4

Cas No:138896-99-8

138896-99-8

R&D Labs maybe for 138896-99-8

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