Synthesis and P–P cleavage reactions of [P(X)X′]2; X-ray structures of [Co{P(X)X′}(CO)3] and P4[P(X)X′]2[X = N(SiMe3)2, X′ = NPri2]

Bezombes, Jean-Philippe; Hitchcock, Peter B.; Läppert, Michael F.; Nycz, Jacek E.

doi:10.1039/b315793h

Cited by 105 publications

(73 citation statements)

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“…[22] The reaction described here displays close anal- Communications ogies to the recently reported "non-oxidative" insertion of a metal atom into the PÀC bond of a phosphenium-carbene adduct. [23] Remarkably, unlike tetraaminodiphosphanes that may easily decay into two phosphanyl radicals, [24] 5 a,b fail to react with P 4 under addition to a PÀP bond even in boiling toluene; possibly, this may indicate a certain complementary nature of reactions involving radical (R 2 P··PR 2 ) or ionic (R 2 P + À PR 2 ) activation of a PÀP bond.…”

Section: (5 B)mentioning

confidence: 96%

Diphosphanes with Polarized and Highly Reactive PP Bonds

2004

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Single bonds are described in the valence-bond (VB) model in terms of resonance between covalent and ionic canonical structures (Scheme 1).[1] Whereas the covalent canonical structure is dominant for homoatomic bonds (AÀB), the weight of the appropriately polarized ionic canonical structure prevails for heteroatomic bonds with a large electronegativity difference (cA ! cB). As a result, this leads to a lower covalent bond order and a substantial bond polarityWe reported in 2000 on the hydride reactivity of 2-hydridodiazaphospholenes 1, and interpreted this behavior as a consequence of a polarization P d+ ÀH dÀ of the PÀH bond that can be explained in terms of a hyperconjugation between the six p electrons in the C 2 N 2 moiety and the s*(PÀH) orbital. [2] In the frame of the VB model, this indicates that ionic canonical structures contribute, regardless of the low electronegativity difference (c AR (H) 2.2, c AR (P) 2.06), significantly to the bonding. The cause of this effect lies in the high cation stability of the diazaphospholenium fragment which yields an energetic stabilization of canonical structures such as 1'' and 1''', and provides, for example, the driving force for the increased tendency towards dissociation of P-halogeno-1,3,2-diazaphospholenes.[3] Following this principle, a combination of a diazaphospholenium with a stable anionic phosphanide fragment should likewise render the polarization of the homoatomic PÀP bond of a diphosphane feasible. Herein we describe the synthesis and characterization of such derivatives, and the unusual reactivity of the PÀP bond resulting from the polarization will be demonstrated.First attempts at the synthesis of P-phosphanyldiazaphospholenes were made starting from lithium diphenylphosphanide (2) or lithium tetraethyl phospholide (3), [4] whose high anion stability offer particularly suitable conditions for a dipolar polarization of the PÀP bond. The reaction of 2 or 3 with an equivalent of the P-chlorodiazaphospholene 4 in THF yielded cleanly the target compounds 5 a,b, which were isolated after workup as yellow, crystalline solids that are sensitive to hydrolysis and were characterized by means of spectroscopic and analytical studies (Scheme 2).Whereas the spectroscopic data are not very unusual, [5] Xray crystal structural studies [6] furnished clear evidence for a weakening of the PÀP bond that is expected as the result of an increased weight of ionic canonical structures such as 5'''. The P1ÀP2 bond length in 5 a (2.334(1) , Figure 1) is substantially longer than typical PÀP distances in diphosphanes (2.217 AE 0.08 [8] ) and exceeds even the distances in the sterically overcrowded [{(Me 3 Si) 2 CH} 2 P] 2 (2.310 ), [9] which dissociates easily under homolytic cleavage of the PÀP bond to give two radicals, and in the 1,1-diaminodiphosphane (iPr 2 N) 2 PÀPPh 2 (2.250 ), [10] for which, owing to the significantly lower cation stability of (iPr 2 N) 2 P + as compared to a diazaphospholenium cation, [3] a less pronounced dipolar polarization of the PÀP bond is expe...

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Section: (5 B)mentioning

confidence: 96%

Diphosphanes with Polarized and Highly Reactive PP Bonds

2004

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“…Sr cov = 2.22 ), [36] although the bonds to P1a (2.150(2) ) are somewhat shortened owing to bond polarization. [25,26,32,[37][38][39][40][41] No close contacts are found between anion and cation. [36] Ad istorted tetrahedral coordination environment is found for P1a, which can be compared to tetracoordinate Pa toms in cyclic phosphinohalophosphonium ions or bicyclic Te rP 4 Me·B(C 6 F 5 ) 3 (Ter = 2,6-dimesitylphenyl).…”

Section: Angewandte Communicationsmentioning

confidence: 99%

Low‐Temperature Isolation of the Bicyclic Phosphinophosphonium Salt [Mes*₂P₄Cl][GaCl₄]

et al. 2015

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The reaction of [ClP(μ-PMes*)]2 (1) with the Lewis acid GaCl3 yielded a hitherto unknown tetraphosphabicyclo[1.1.0]butan-2-ium salt, [Mes*P4(Cl)Mes*][GaCl4] (3[GaCl4]), which incorporates a positively charged phosphonium center within its bicyclic P4 scaffold. The formation of the title compound was studied by means of low-temperature NMR experiments. This led to the identification of an intermediate cyclotetraphosphenium cation, which was trapped by reaction with dimethylbutadiene (dmb). All of the compounds were fully characterized by experimental and computational methods.

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“…It should be mentioned that Lappert et al have reported the synthesis of four coordinated Co( i ) tricarbonyl, [{(Me 3 Si) 2 N}( i Pr 2 N)P]Co(CO) 3 , by the reaction of the in situ generated phosphinyl radical [{(Me 3 Si) 2 N}( i Pr 2 N)P]˙ with Co 2 (CO) 8 . 17 This cobalt( i ) phosphido complex also adopts tetrahedral coordination geometry, as shown by X-ray diffraction analysis. Thus, complex 3 can be considered analogous to Lappert's cobalt( i ) phosphido complex minus one electron.…”

Section: Introductionmentioning

confidence: 83%

Persistent four-coordinate iron-centered radical stabilized by π-donation

et al. 2016

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Synthesis and P–P cleavage reactions of [P(X)X′]₂; X-ray structures of [Co{P(X)X′}(CO)₃] and P₄[P(X)X′]₂[X = N(SiMe₃)₂, X′ = NPrⁱ₂]

Cited by 105 publications

References 14 publications

Diphosphanes with Polarized and Highly Reactive PP Bonds

Diphosphanes with Polarized and Highly Reactive PP Bonds

Low‐Temperature Isolation of the Bicyclic Phosphinophosphonium Salt [Mes*₂P₄Cl][GaCl₄]

Persistent four-coordinate iron-centered radical stabilized by π-donation

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Synthesis and P–P cleavage reactions of [P(X)X′]2; X-ray structures of [Co{P(X)X′}(CO)3] and P4[P(X)X′]2[X = N(SiMe3)2, X′ = NPri2]

Cited by 105 publications

References 14 publications

Diphosphanes with Polarized and Highly Reactive PP Bonds

Diphosphanes with Polarized and Highly Reactive PP Bonds

Low‐Temperature Isolation of the Bicyclic Phosphinophosphonium Salt [Mes*2P4Cl][GaCl4]

Persistent four-coordinate iron-centered radical stabilized by π-donation

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Synthesis and P–P cleavage reactions of [P(X)X′]₂; X-ray structures of [Co{P(X)X′}(CO)₃] and P₄[P(X)X′]₂[X = N(SiMe₃)₂, X′ = NPrⁱ₂]

Low‐Temperature Isolation of the Bicyclic Phosphinophosphonium Salt [Mes*₂P₄Cl][GaCl₄]