Valenzisomerisierung eines 1,3-Diphosphacyclobutan-2,4-diyls: photochemischer Ringschluß zum 2,4-Diphosphabicyclo[1.1.0]butan und dessen thermische Ringöffnung zumgauche-1,4-Diphosphabutadien

Niecke, Edgar; Fuchs, André; Nieger, Martin

doi:10.1002/(sici)1521-3757(19991018)111:20<3213::aid-ange3213>3.0.co;2-l

Cited by 65 publications

(3 citation statements)

References 21 publications

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“…The X-ray crystal structure of the exo isomer revealed two different triclinic polymorphs with Z = 2 and Z = 6, respectively, and very similar molecular structures. Polymorph I shows a folding angle (113.27(10)8) and a transannular bond length (1.510 (2) ) that are similar to those of exo-3 a. Heating of isolated 3 b (exo + endo, 4:1) in toluene at 50 8C for 60 h gave the favored phosphacyclobutene cis-5 b, indicating that valence isomerization of the novel 2-phosphabicyclo-[1.1.0]butanes is indeed directed by the bridgehead substituents (3 b 50 8C; 3 a 130 8C).…”

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confidence: 99%

Valence Isomerization of 2‐Phosphabicyclo[1.1.0]butanes

et al. 2005

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The unique electronic properties of the strained bicyclo-[1.1.0]butanes [1] are enhanced by the heteroatoms in the molecular frame. Illustrative is the bond-stretch isomerization of the P 2 C 2 and P 2 B 2 bicycles.[2] However, very few systems are known with a single heteroatom, [3] probably because of their high reactivity, which is only moderated when the heteroatom occupies a bridgehead position as in the 1-aza derivatives. [4] The increased reactivity of the hetero systems is due to the valence isomerization to which the bicyclo[1.1.0]butanes are prone. We now report on the first 2-phospha derivatives.The carbene-like phosphinidene Ph-P = W(CO) 5 [5] was generated in situ by cheletropic elimination from 1 at 110 8C in toluene and then allowed to react with cyclopropene 2 a [6] (Scheme 1). This led to the desired W(CO) 5 -complexed 2-phosphabicyclo[1.1.0]butanes exo-3 a (d 31 P = À85.1 ppm) and endo-3 a (d 31 P = À36.7 ppm) [7] in a 10:9 ratio, which were isolated in 69 % yield as colorless solids. The remarkably

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confidence: 99%

Valence Isomerization of 2‐Phosphabicyclo[1.1.0]butanes

et al. 2005

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“…Illustrative is the bond-stretch isomerization of the P 2 C 2 and P 2 B 2 bicycles. [2] However, very few systems are known with a single heteroatom, [3] probably because of their high reactivity, which is only moderated when the heteroatom occupies a bridgehead position as in the 1-aza derivatives. [4] The increased reactivity of the hetero systems is due to the valence isomerization to which the bicyclo[1.1.0]butanes are prone.…”

mentioning

confidence: 99%

Valence Isomerization of 2‐Phosphabicyclo[1.1.0]butanes

et al. 2005

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The unique electronic properties of the strained bicyclo-[1.1.0]butanes [1] are enhanced by the heteroatoms in the molecular frame. Illustrative is the bond-stretch isomerization of the P 2 C 2 and P 2 B 2 bicycles. [2] However, very few systems are known with a single heteroatom, [3] probably because of their high reactivity, which is only moderated when the heteroatom occupies a bridgehead position as in the 1-aza derivatives. [4] The increased reactivity of the hetero systems is due to the valence isomerization to which the bicyclo[1.1.0]butanes are prone. We now report on the first 2-phospha derivatives.The carbene-like phosphinidene Ph-P = W(CO) 5 [5] was generated in situ by cheletropic elimination from 1 at 110 8C in toluene and then allowed to react with cyclopropene 2 a [6] (Scheme 1). This led to the desired W(CO) 5 -complexed 2-phosphabicyclo[1.1.0]butanes exo-3 a (d 31 P = À85.1 ppm) and endo-3 a (d 31 P = À36.7 ppm) [7] in a 10:9 ratio, which were isolated in 69 % yield as colorless solids. The remarkably

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“…However, little is known about the phosphorus-containing analogues [19][20][21][22]. In our ongoing research on small strained organophosphorus ring systems, we became interested in the yet unknown 2-phospha-4-silabicyclo[1.1.0]butanes, whose occurrence we reported as a reactive intermediate recently [23,24].…”

Section: 3mentioning

confidence: 95%

Valence isomerization of 2-phospha-4-silabicyclo[1.1.0]butane:a high-level ab initio study

Slootweg¹,

Ehlers²,

Lammertsma³

Highlights in Computational Chemistry II

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The rearrangements for 2-phospha-4-silabicyclo[1.1.0]butane, analogous to the valence isomerization of the hydrocarbons bicyclobutane, 1,3-butadiene, and cyclobutene, were studied at the (U)QCISD(T)/6-311+G**//(U)QCISD/6-31G* level of theory. The monocyclic 1,2-dihydro-1,2-phosphasiletes are shown to be the thermodynamically preferred product, in contrast to the isomerization of the hydrocarbons, which favors the 1,3-butadiene structure. Furthermore, an unprecedented direct isomerization pathway to the 1,2-dihydro-1,2-phosphasiletes was identified. This pathway is competitive with the isomerization via the open-chain butadienes and becomes favorable when electron-donating substituents are present on silicon.

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Valenzisomerisierung eines 1,3-Diphosphacyclobutan-2,4-diyls: photochemischer Ringschluß zum 2,4-Diphosphabicyclo[1.1.0]butan und dessen thermische Ringöffnung zumgauche-1,4-Diphosphabutadien

Cited by 65 publications

References 21 publications

Valence Isomerization of 2‐Phosphabicyclo[1.1.0]butanes

Valence Isomerization of 2‐Phosphabicyclo[1.1.0]butanes

Valence Isomerization of 2‐Phosphabicyclo[1.1.0]butanes

Valence isomerization of 2-phospha-4-silabicyclo[1.1.0]butane:a high-level ab initio study

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