Phosphorus reaction with carbene complexes

Alkoxide anion abstraction by a Lewis acid from phosphorus ligand on a transition metal is one of the most useful methods to prepare cationic phosphenium complexes. It has been reported that OR anion abstraction from an alkoxyalkyl ligand, C(OR)R2, on a transition metal complex leads to the formation of a cationic carbene complex.39-42 It is similarly expected that OR anion abstraction from an alkoxysilyl ligand, Si(OR)R2, would cause the formation of a cationic silylene complex. Therefore, increased attention has been focused on the reaction with a Lewis acid of transition metal complexes bearing both alkoxyalkyl and phosphite ligands and of complexes bearing both alkoxysilyl and phosphite ligands. 

Reaction of (l-alkynyl)carbene complexes with nitrogen- or phosphorus-containing compounds makes available a large variety of products. Among these are (enamino)carbene and ( enphosphino )carbene complexes, both of which have been widely used for the generation of organic products. 

An aminophosphinidene complex Cp Os(CO)2 PCl(N-Tr2) was prepared by reaction of [Cp Os(CO)2] with Tr2NPCl2. As with Fischer carbenes (see Fischer-type Carbene Complexes), the nitrogen group stabilizes the electron-deficient phosphorus atom of the phosphinidene ligand. Based on a crystal structure of the ruthenium analog, there is likely... 

Recently, the formation of the first carbene complex of a phosphorus(V) center was reported. The direct reaction of carbene (1) (R = Mes, R = H) with phenyltetrafluo-rophosphorane (equation 12) results in the formation of perphosphoranide (107) in quantitative yield. An X-ray structural determination showed that the phosphoms center in (107) adopts an octahedral geometry with a long P C(carbene) bond length (P C(carbene) 1.91 A cf. P-C(phenyl) 1.84A). The P resonance in (93,94) and (96) are at a substantially higher field than the value in (107), which is expected and reflects the change from a two-coordinate to a six-coordinate P center. 

The reactions of P-halophospha-alkenes with carbenes provide a new route to 1-chloro-lH-phosphirines (181). Such compounds are highly reactive, and a study of nucleophilic displacement reactions at phosphorus has been facilitated by preparation of the related P-W(CO)5 complexes.The first pentacoordinate systems derived from phosphirenes, (182), have been formed in the reactions of P-halo- or P-cyano-phosphirenes with tetrachloro-o-quinone. Evidence has been presented for the rearrangement of P-chlorophosphirenium ions (183) to the vinylphosphenium ions (184)... 

A large variety of codimerization reactions under the catalytic action of copper complexes is known. Usually, these reactions proceed via carbene intermediates and provide substituted ethenylcyclopropanes. Most of the catalysts for these reactions consist of copper(I) chloride and a phosphorus ligand, such as triphenylphosphane or triphenyl phosphite. Under the influence of these catalysts, carbenes are presumably formed from various substituted cyclopropenes at temperatures ranging from —40 to - -20°C, and these carbenes can be trapped by reaction with alkenes. ... 

An efficient approach to a new family of highly functionalised phosphorus analogues of a-trifluoromethyl-substituted phenylalanine (492) and its homologues via Ru-catalysed intermolecular ene-yne metathesis has been developed. Thus, cross-metathesis of a-allynyl-a-trifluoromethyl-ot-aminophosphonates (489) with alkenes (490) catalysed by a second-generation Grubbs carbene complex (493) afforded corresponding aminophosphonates (491) with 1,3-diene backbone. Finally, one-pot Diels-Alder reaction-aromatisation step gave desired products (492) (Scheme 146). ... 

Reductive dehalogenation at phosphorus on HCCP can be performed by sodium metal in the presence of a hindered carbene donor ligand (IPr). This reaction was followed by P NMR that revealed a single complex with two differing phosphorus electronic environments, which suggested differing oxidation states [P(III) and P(V)], Scheme 2. Reaction of the complex with... 

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