Phosphorane, carbene complex

The isolation of the first carbene complex of a phosphorane has been reported recently (50). Perphosphoranide (75) was formed in... 

Another attractive route to the synthesis of highly reactive tungsten carbene complexes involves alkylidene transfer from phosphoranes. Arylimido tungsten... 

Thermolysis of ()) -cyclopentadienyl)bis(neopentyl)(tri-methylphosphine)vanadium(I) (82) in the presence of 1,2-bis(dimethylphosphuio)ethane leads to the formation of the Schrock-type see Schrock-type Carbene Complexes) alkylidene vanadium complex (83), which is supported by X-ray crystallographic analysis (Scheme 45). " The imido vanadium complex (84) is converted to the corresponding alkylidene complex (86) on treatment with ben-zylidene(triphenyl)phosphorane (85) via substitution of the phosphine ligand (Scheme 46). ... 

Phosphinidene carbene (6.472) and phosphorane carbene (6.473) complexes are known [8,9]. 

Photochemical Reactions with Alkoxychromium Carbene Complexes. Photolysis of chromium alkoxycarbene complexes in the presence of tosylmethylene phosphorane [or ester stabilized ylides such as (methoxycarbonylmethylene)-triphenylphosphorane] under an atmosphere of carbon monoxide produced aflenes. Such reactive allenes (EWG at C1 and electron donating group at C3) hydrolyzed to give y-keto-a. -unsaturated sulfones with. stereoselectivity (eq 6). ... 

A related three-coordinate dicarbonyl-carbene complex can be obtained by reaction of Ni(CO)4 with the carbodi-phosphorane double ylide Ph3=C=PPh3. The reaction of Ni(GO)4 with Ph3=C=PPh3 in toluene gives the tricarbonyl complex Ni G(PPh3)2 (CO)3, but in THF solvent the deep red 16-electron three-coordinate complex Ni G(PPh3)2 (GO)2 was obtained. Both the three- and four-coordinate compounds Ni G(PPh3)2 (GO) , n = Z, 3) were structurally characterized by X-ray diffraction. ... 

Interest has again continued in studies of the generation and reactivity of phosphinidene species (RP ), phosphorus analogues of carbenes, and this area has been reviewed. A review has also appeared of the use of terminal phosphinidene complexes in the formation of phosphorus-element bonds. Further studies of phosphanylidene-a -phosphoranes, RP = PR3, (regarded as phosphine-complexed phosphinidenes, i.e., ArP -PRs), have shown that the species Me3P=PAr (Ar = Mes or 2,6-Mes2C6H3) are good vehicles for the delivery of the terminal phosphinidene moiety ArP to zirconium and vanadium sites. Terminal phosphinidene complexes of cobalt, ruthenium, rhodium and osmium, and iridium, have also been... 

Geminally dimetallated gold-copper complexes derived from carbodi-phosphoranes and phosphinidene-carbene adducts have been prepared... 

The reaction can be envisioned as proceeding via nucleophilic attack by the phosphorane carbon atom on the electron-deficient carbene carbon atom to form a betaine-like intermediate (XXVI) which subsequently fragments to form an enol-ether complex and free triphenylphosphine which then react to give the observed products (see Scheme 14). The observation of (CO)s-WP(CgH4CH3)3 in the product mixture when the reaction was carried out in the presence of P(CeH4CH3)3 supports this mechanism. 

The reaction of phosphoranes with alkylmethoxycarbene complexes fails to produce vinyl ethers owing to abstraction of a proton from the carbon alpha to the carbene carbon atom. However, the less basic diazoalkanes react... 

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