- Remarkable Differences in the Reactivities of the (E)- and (Z)-Isomers of a Phospha-alkene
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The (E)- and (Z)-isomers of the phospha-alkene, But(Me3SiO)C=PSiMe3, show markedly different reactivities towards heat and molecular oxygen.
- Barron, Andrew R.,Cowley, Alan H.,Hall, Stephen W.
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- The osmium-silicon triple bond: Synthesis, characterization, and reactivity of an osmium silylyne complex
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The first silylyne complex of a metal beyond group 6, [Cp*( iPr3P)(H)Os≡Si(Trip)][HB(C6F 5)3], was prepared by a new synthetic route involving hydride abstraction from silicon. NMR and DFT computation
- Hayes, Paul G.,Xu, Zhenggang,Beddie, Chad,Keith, Jason M.,Hall, Michael B.,Tilley, T. Don
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supporting information
p. 11780 - 11783
(2013/09/02)
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- Differing reactivities of PCMe and PCBut towards a triphosphabenzene and a tetraphosphabarrelene: Synthesis of new phosphaalkyne pentamers (P5C5MenBut5-n, n = 0, 1 or 2)
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The reaction of excess PCMe with the triphosphabenzene, 1,3,5-P 3C3But3, yields a phosphaalkyne pentamer, P5C5Me2But3, which displays a pentaphosphaisolumibullvalene core structure. Its treatment with [W(CO)5(THF)] gives a complex of this cage, [{W(CO) 5}2(-η1:η1-P 5C5Me2But3)], which has been structurally characterised. In contrast, the previously reported reaction of PCBut with 1,3,5-P3C3But 3, affords, in addition to the known tetraphosphabarrelene, 1,3,5,7-P4C4But4, a new phosphaalkyne pentamer (P5C5But5), which has a partially unsaturated "open cage" core. Although PCBu t does not react with 1,3,5,7-P4C4Bu t4, the reaction of PCMe with the tetraphosphabarrelene is shown to give a mixture of products. Treatment of these with [W(CO) 5(THF)] leads to the isolation of the tungsten carbonyl complex, [{W(CO)5}{W(CO)4}(-η1:η4- P5C5MeBut4)], which has been structurally characterised. This study suggests that PCMe has a significantly greater reactivity towards cycloadditions than its bulkier counterpart, PCBut. The Royal Society of Chemistry 2007.
- Jones, Cameron,Schulten, Christian,Stasch, Andreas
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p. 1929 - 1933
(2008/02/03)
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- Phosphaalkynes from acid chlorides via P for O(CI) metathesis: A recyclable niobium phosphide (P3-) reagent that effects C-P triple-bond formation
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Reported herein is a new, metathetical P for O(Cl) exchange mediated by an anionic niobium phosphide complex that furnished phosphaalkynes (RC≡P) from acid chlorides (RC(O)Cl) under mild conditions. The niobaziridine hydride complex, Nb(H)(tBu(H)C=NAr)(N[Np]Ar)2 (1, Np = neopentyl, Ar = 3,5-Me2C6H3), has been shown previously to react with elemental phosphorus (P4), affording the μ-diphosphide complex, (μ2:η2,η2-P2)[Nb(N[Np]Ar)3]2, (2), which can be subsequently reduced by sodium amalgam to the anonic, terminal phosphide complex, [Na][PNb(N[Np]Ar)3] (3). It is now shown that treatment of 3 with either pivaloyl (t-BuC(O)Cl) or 1-adamantoyl (1-AdC(O)Cl) chloride provides the thermally unstable niobacyles, (t-BuC(O)P)Nb(N[Np]Ar)3 (4-t-Bu) and (1-AdC(O)P)Nb(N[Np]Ar)3 (4-1-Ad), which are intermediates along the pathway to ejection of the known phosphaalkynes t-BuC≡P (5-t-Bu) and 1-AdC≡P(5-1-Ad). Phosphaalkyne ejection from 4-t-Bu and 4-1-Ad proceeds with formation of the niobium(V) oxo complex ONb(N[Np]Ar)3 (6) as a stable byproduct. Preliminary kinetic measurements for fragmentation of 4-t-Bu to 5-t-Bu and 6 in C6D6 solution are consistent with a first-order process, yielding the thermodynamic parameters ΔH? = 24.9 ± 1.4 kcal mol-1 and ΔS? = 2.4 ± 4.3 cal mol-1 K-1 over the temperature range 308-338 K. Separation of volatile 5-t-Bu from 6 after thermolysis has been readily achieved by vacuum transfer in yields of 90%. Pure 6 is recovered after vacuum transfer and can be treated with 1.0 equiv of triflic anhydride (Tf2O, Tf = O2SCF3) to afford the bistriflate complex, Nb(OTf)2(N[Np]Ar)3 (7), in high yield. Complex 7 provides direct access to 1 upon reduction with magnesium anthracene, thus completing a cycle of element activation, small-molecule generation via metathetical P-atom transfer, and deoxygenative recycling of the final niobium(V) oxo product. Copyright
- Figueroa, Joshua S.,Cummins, Christopher C.
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p. 13916 - 13917
(2007/10/03)
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- Lewis acid mediated spirocyclotrimerization of phosphaalkynes -key step for the selective and of triphospfaa dewar benzenes
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In the presence of Lewis acidic derivatives of group 13 elements, phosphaalkynes 7 undergo spirocvclotrimerization with incorporation of the corresponding Lewis acids to form 10a-f. Scope and limitations of this novel cyclooligomerization process are examined. Starting from the spirocyclotrirner 10a reaction with the Lewis base dimethyl sulfoxide, we have in hand for the first time a method for the selective genera-tion of two isomeric triphospha Dewar benzene derivatives (18, 19). Both can be trapped efficiently by further reaction with the phosphaalkyne to furnish the two novel phosphaalkyne cyclotetramers 20 and 21, both still possessing a phosphorus-carbon double bond, In the case of 21, further functionalization of the phosphaalkene unit is possible by [3 + 2] cycloaddition with a nitrile oxide (→ 23). VCH Veriagsgesellschafi mbH, 1996.
- Breit, Bernhard,Regitz, Manfred
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p. 489 - 494
(2007/10/03)
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- DIPHENYLBORYLDIPIVALOYLPHOSPHIDE - THE FIRST EXAMPLE OF BORYLATED 2-PHOSPHA-1,3-DIONATE
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C-Trimethylsiloxy substituted phosphaalkene 1 reacts exothermically with diphenylchloroborane.The expected spontaneous 1,3-elimination of trimethylsiloxydiphenylborane took place to give phosphaalkyne 3 in 1-2percent yield only.The symmetrization of intermediately formed C-diphenylboroxysubstituted phosphaalkene 2 into (diphenylboryl)dipivaloylphosphide 4 was found to be the main way of the reaction.
- Ionkin, A. S.,Chertanova, L. F.,Arbuzov, B. A.
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p. 133 - 136
(2007/10/02)
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- Phosphaalkine - Synthesen, Reaktionen, Koordinationsverhalten
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Organophosphorverbindungen werden auf zweierlei Art in der Synthesechemie eingesetzt: Entweder dienen sie als Hilfsreagentien wie etwa bei der Wittig-Reaktion, oder sie werden selbst in die Zielmolekuele eingebaut.Gerade das zweite Anwendungsfeld hat sich durch die Herstellung niederkoordinierter Phosphorverbindungen in den letzten Jahren enorm erweitert.Zu den niederkoordinierten Phosphorverbindungen zaehlen auch Phosphaalkine, die im Mittelpunkt dieses Beitrags stehen und viel Interesse sowohl bei Organikern als auch bei Anorganikern gefunden haben.Der Einbau der PC-R-Einheit in Heterocyclen, in Phosphaarene und deren Valenzisomere sowie in polycyclische Verbindungen, die Verwendung als neue Ligandensysteme in der Komplexchemie und schliesslich die Cyclooligomerisierung mit Organometallreagentien belegen dies auf eindrucksvolle Weise.Phosphaalkine haben bezueglich ihrer Reaktivitaet wenig mit Nitrilen gemeinsam, zeigen aber um so mehr Verwandtschaft mit den isoelektronischen Alkinen.
- Regitz, Manfred,Binger, Paul
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p. 1541 - 1565
(2007/10/02)
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- Phosphorus Compounds with Unusual Coordination, 19. - 1,2,4-Diazaphospholes by Cycloaddition of Diazo Compounds onto a Stable Phosphaalkyne
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Diazomethyl compounds (2a-h) add regiospecifically onto the phosphaalkyne 1 to the adducts 3 which isomerize by spontaneous H-shift to the 1,2,4-diazaphospholes 4a-h.Onty at the reaction 2i+1 the H-shift is suppressed in favour of a trimethylsilyl migration (->6i).Also at the addition of α-diazo ketones 7a-e onto 1 the primary adducts 8 cannot be isolated as they isomerize by fast acyl-shift to N-acceptor-substituted diazaphospholes (9a-e).In the case of 7a-c parallel to that formation of isomers (11a-c) can be demonstrated.The corresponding reaction sequence of the phosphaalkyne 1 with cyclic α-diazo ketones (12, 14, 16, 18) makes easily accessible annelated representatives of the same structural type (13, 15, 17, 19).Phosphoryl group migrations are responsible for the formation of phosphorylated 1,2,4-diazaphospholes (24-c) at the reaction 1+20a-c.N-Acyl and -phosphoryl groups of the rearranged cycloadducts are easily solvolysed (9a-e -> 4b,c,j,k; 24a-c -> 4b,c; 13 -> 25).
- Roesch, Wolfgang,Hees, Udo,Regitz, Manfred
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p. 1645 - 1652
(2007/10/02)
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- Acyl- and Alkylidenephosphines, XV. 2,2-Dimethylpropylidynephosphine, a Stable Compound with a Phosphorus Atom of Coordination Number 1
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In the presence of small amounts of solid sodium hydroxide, -trimethylsilylphosphine reacts at +20 deg C to give hexamethyldisiloxane and 2,2-dimethylpropylidynephosphine (2).In contrast to similar alkylidynephosphines this compound is stable at room temperature.The IR and mass spectrum are discussed, and 1H, 13C and 31P NMR spectral data are given. - Keywords: Alkylidynephosphines, 2,2-Dimethylpropylidynephosphine, P-C Triple Bond
- Becker, Gerd,Gresser, Gudrun,Uhl, Werner
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