THE REACTION OF TERMINAL PHOSPHINIDENE COMPLEXES WITH ELECTRON-RICH ALKYNES: A NEW APPROACH TO THE PHOSPHOLE RING

Abstract

The reaction of electron-rich alkynes such as ethoxyacetylene or propynyldiethylamine with a transient terminal phosphinidene complex such as [PhP?W(CO)₅] directly yields the corresponding phosphole complexes via a formal [2 + 2 + I] cycloaddition involving two molecules of alkyne and one phosphorus center.     

Formation,Detection, and Reactions of Phosphinidenes (Phosphanediyls)

Formation and detection of phosphinidenes (R? P?:) in the decomposition of cyclophosphanes and in the reaction of dichlorophosphanes with metals are considered critically. Only in the thermolysis of pentaphenylcyclopentaphosphane can phenylphosphinidene be detected with certainty by pyrolysis-mass spectroscopy. “Trapping reactions” such as “insertion” into S? S or As? As bonds, and addition reactions with 1,2-diketones, 1,3-dienes, or alkynes can also be interpreted without the assumption of free phosphinidenes. The pyrolysis products of cyclophosphanes add to 1,3-dienes and alkynes, yielding five- and six-membered heterocycles that contain one to three phosphorus atoms.     

The Development of a Carbene-like Chemistry with Terminal Phosphinidene Complexes

When compared to the chemistry of other well-known electron-deficient species such as carbenes, silylenes, and nitrenes, the chemistry of phosphinidenes RP: is extremely underdeveloped. A critical survey of the literature indicates that this state of affairs probably reflects both an inadequate access to these species and an intrinsic lack of reactivity. Theoretical calculations suggest that it is possible to boost the electrophilicity and to stabilize the singlest state of phosphinidenes by complexation with transition-metal moieties such as M(CO)₅ (M?Cr, Mo, W). The corresponding terminal phosphinidene complexes [RP?M(CO)₅] show a rich and varied chemistry which often parallels the chemistry of singlet carbenes. Phosphinidene complexes are presently easily accessible through thermal decomposition of 7-phosphanorbornadiene complexes, but their stabilization remains a challenge to be met.     

Reactivity of electrophilic terminal phosphinidene complexes toward phosphorus ylides

Stabilised phosphorus ylides react with transient terminal phosphinidene complexes [RP---W(CO)₅] (R=Ph, Me) to give products resulting from a formal insertion of P into a C---H bond via an initial nucleophilic attack of the ylidic carbon.     

Activation of P4 and P2 by Transition Metal Complexes at Room Temperature

The first complex with P ₂ as an eight-electron donor diphosphinidene ligand is 1 , which forms at room temperature from [Cp*(OC)₂Re]₂ and P₄ (Cp*=C₅Me₅). The by-product of this reaction, which has a Re₂P₂ butterfly structure, reacts with [W(CO)₅(thf)] at room temperature to give two multinuclear complexes—one with a ReWP₂ tetrahedrane framework and 2 , whose six atoms Re₂P₂W₂ form a plane and in which the P₂ ligand of the butterfly complex is converted into two µ-P ligands.     

Fluorinated Heterobutadienes/Trimethylphosphine: A Reactivity Study

The reactions of fluorinated heterobutadienes F 2 C=X--C(R)=Y (X = N, CH; Y = O, N-Mes; R = Ph, t-Bu), A-D , with the PMe 3 were studied. In any case, a different reaction pathway was observed, depending on the specific nature of A-D . These reactions lead to some novel organophosphorus species, including P-ylides and u 5 -azaphosphinines. u 5 -phospholenes, as observed with phosphites, for example, were not observed, but with phosphinidine (P--Ph), the heterobutadienes B and C form u 3 -oxazaphospholenes. Therein the complex (Me 3 P) 3 Ni[cyclo-P(Ph)OC(Ph)NC(CF 3 ) 2 ] was obtained and structurally characterized.     

Frustrated Lewis Pair Adduct of Atomic P(−1) as a Source of Phosphinidenes (PR), Diphosphorus (P2), and Indium Phosphide

We report phosphinidenes (PR) stabilized by an intramolecular frustrated Lewis pair (FLP) chelate. These adducts include the parent phosphinidene, PH, which is accessed via thermolysis of coordinated HPCO. The reported FLP-PH species acts as a springboard to other phosphorus-containing compounds, such as FLP-adducts of diphosphorus (P₂) and InP₃. Our new adducts participate in thermal- or light-induced phosphinidene elimination (of both PH and PR, R=organic group), transfer P₂ units to an organic substrate, and yield the useful semiconductor InP at only 110 °C from solution.