P6tBu4—The First 1,1′‐Bicyclotriphosphane

Baudler, M.; Makowka, B.

doi:10.1002/anie.198409871

Cited by 13 publications

(5 citation statements)

References 14 publications

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“…Approximate values for δ P and J PP can be estimated by simple examination of the experimental spectrum [19] ; starting from these values the spectrum can be solved by iterative fitting [20] (Figure 4). The 31 P-NMR data of 12 parallel, to a large degree, those of tBu 2 P 3 ϪP 3 tBu 2 [16] . The chemical shifts of the phosphorus nuclei appear at high field [δ(P-1) ϭ Ϫ142.6, δ(P-2) ϭ Ϫ194.8, δ(P-3) ϭ Ϫ210.8], as is generally found for δ 31 P in cyclotriphosphanes [23] [24] .…”

Section: (1a)mentioning

confidence: 67%

“…In accord with this is also the sequence of magnitudes of 1 J P1P2 (Ϫ284.7 Hz) and 1 J P1P3 (Ϫ174.9 Hz) [22] . Obviously, like tBu 2 P 3 ϪP 3 tBu 2 [16] , 12 also forms the sterically J P2P2Ј (7.6 Hz) and 3 J P3P3Ј (0.4 Hz) are found to have the reverse order of magnitude. This difference, as well as the clearly more negative coupling constant 3 J P2P3Ј (Ϫ14.1 Hz) observed for 12, is presumably caused by a larger population of the rotamers with a wider torsion angle P-2,P-1,P-1Ј,P-2Ј.…”

Section: (1a)mentioning

confidence: 91%

“…Unfortunately, the compounds 11Ϫ13 (see Scheme 4) have not so far been isolated in their pure state; however, their structures, as shown by the formula, can be proved unambiguously from their 31 P-NMR spectra (see below). The 31 P-NMR data of phosphorus compounds of type 11 (tBu 2 P 3 H [15] ), 12 (P 6 tBu 4 [16] ), and 13 (P 6 tBu 4 [17] , P 6 Cp* 4 [18] ), which were already known, were also quite helpful for this purpose. Other isomers of the cyclophosphanes 11Ϫ13 could not be spectroscopically detected using NMR.…”

Section: (1a)mentioning

confidence: 98%

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The Triphosphide (tBu3Si)2P3Na: Formation, X-ray and Ab initio Structure Analyses, Protonation and Oxidation to Triphosphane (tBu3Si)2P3H and Hexaphosphanes (tBu3Si)4P6⋆

Wibeŕg¹,

Wörner²,

Lerner³

et al. 1998

Eur. J. Inorg. Chem.

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Section: (1a)mentioning

confidence: 67%

Section: (1a)mentioning

confidence: 91%

Section: (1a)mentioning

confidence: 98%

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The Triphosphide (tBu3Si)2P3Na: Formation, X-ray and Ab initio Structure Analyses, Protonation and Oxidation to Triphosphane (tBu3Si)2P3H and Hexaphosphanes (tBu3Si)4P6⋆

Wibeŕg¹,

Wörner²,

Lerner³

et al. 1998

Eur. J. Inorg. Chem.

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“…[19] The reaction pathway represents in essence a reversal of the dechlorostannylation that has been established as a smooth synthetic route to oligophosphanes, [20] and may be regarded to provide an experimental clue for a comparatively low P À P bond energy in 5 a. Analogous reactions to those for 5 a were also observed for 5 b.…”

Section: (5 B)mentioning

confidence: 88%

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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“…The use of 1 as a cyclo-(P4 17 The number of bis-cyclooligophosphanes and bicyclic compounds obtained in pure form is still small, 27,[52][53][54][55][56][57][58][59][60] and to the best of our knowledge only six structurally characterised compounds are known to date, namely P6R4 (R = t Bu, Cp), 52,58 {cyclo-(P5 t Bu4}2, 17 {cyclo-(P4 t Bu3)P t Bu}2, 17 {cyclo-(P4 t Bu3)}2 61 and its pentalane analogue 25 .…”

Section: Reactivity Of 1: Synthesis Of Neutral Oligophosphanesmentioning

confidence: 99%