Synthesis and Structure of Tetraorganoguanidinyl-Substituted Phosphorus-Halogen Compounds and of Tris-N-(N′,n′,n″,n″-Tetramethyl) Guanidinyl-Phosphonium Salts

Münchenberg, Jochen; Thönnessen, Holger; Jones, Peter G.; Schmutzler, Reinhard

doi:10.1080/10426509708044198

Cited by 22 publications

(8 citation statements)

References 18 publications

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“…We have found that PCl 5 reacts exothermically with an excess of TMG in methylene chloride, toluene, or chlorobenzene at −30 °C to give (tmg) 3 PCl + Cl - (see also ref b) as the only phosphorus-containing product ( 31 P NMR: −17.1 ppm). This salt is a key precursor for preparation of the HCl or HBF 4 salts of (tmg) 3 PNH and (tmg) 3 PN-Et, which were synthesized by passing ammonia through or adding ethylamine/triethylamine (1:1 mixture) to the chlorobenzene (methylene chloride) solution of (tmg) 3 PCl + Cl - , respectively (monitored by means of 31 P NMR, eq 10): The tert -butylimino-tris(tetramethylguanidino)phosphazene·HCl salt, a precursor to tert -butylimino-tris(tetramethylguanidino)phosphazene, was synthesized by the Kirsanov method (eq 11): …”

Section: Resultsmentioning

confidence: 94%

“…Depending on the ratio of the reactants and the steric hindrance of the amine, either tris(alkylamino)chlorophosphonium chloride or tetrakis(alkylamino)phosphonium chloride was synthesized. It has been shown that the reaction of PCl 5 with tetramethyl- N -trimethylsilylguanidine afforded bis(tetramethylguanido)dichlorophosphonium chloride . In a more recent publication, a possibility to generate tris(guanidino)chlorophosphonium chloride in 60% yield from Me 3 Si−TMG was mentioned, but no characterization data for the compound were given …”

Section: Resultsmentioning

confidence: 99%

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Guanidinophosphazenes: Design, Synthesis, and Basicity in THF and in the Gas Phase

et al. 2005

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A principle for creating a new generation of nonionic superbases is presented. It is based on attachment of tetraalkylguanidino, 1,3-dimethylimidazolidine-2-imino, or bis(tetraalkylguanidino)carbimino groups to the phosphorus atom of the iminophosphorane group using tetramethylguanidine or easily available 1,3-dimethylimidazolidine-2-imine. Seven new nonionic superbasic phosphazene bases, tetramethylguanidino-substituted at the P atom, have been synthesized. Their base strengths are established in tetrahydrofuran (THF) solution by means of spectrophotometric titration and compared with those of eight reference superbases designed specially for this study, P2- and P4-iminophosphoranes. The gas-phase basicities of several guanidino- and N',N',N'',N''-tetramethylguanidino (tmg)-substituted phosphazenes and their cyclic analogues are calculated, and the crystal structures of (tmg)3P=N-t-Bu and (tmg)3P=N-t-Bu x HBF4 are determined. The enormous basicity-increasing effect of this principle is experimentally verified for the tetramethylguanidino groups in the THF medium: the basicity increase when moving from (dma)3P=N-t-Bu (pKalpha = 18.9) to (tmg)3P=N-t-Bu (pKalpha = 29.1) is 10 orders of magnitude. A significantly larger basicity increase (up to 20 powers of 10) is expected (based on the high-level density functional theory calculations) to accompany the similar gas-phase transfer between the (dma)3P=NH and (tmg)3P=NH bases. Far stronger basicities still are expected when, in the latter two compounds, all three dimethylamino (or tetramethylguanidino) fragments are replaced by methylated triguanide fragments, (tmg)2C=N-. The gas-phase basicity (around 300-310 kcal/mol) of the resulting base, [(tmg)2C=N-]3P=NH, having only one phosphorus atom, is predicted to exceed the basicity of (dma)3P=NH by more than 40 powers of 10 and to surpass also the basicity of the widely used commercial [(dma)3P=N]3P=N-t-Bu (t-BuP4) superbase.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Guanidinophosphazenes: Design, Synthesis, and Basicity in THF and in the Gas Phase

et al. 2005

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“…by more than 12 kcal/mol [24] . Schmutzler and co‐workers attempted to synthesize P(tmg) 3 via several reaction pathways, noting that the phosphine should possess extraordinary basicity [25–28] . Although they succeeded in isolating the P‐protonated form, the free phosphine P(tmg) 3 could not be liberated.…”

Section: Introductionmentioning

confidence: 99%

“… [24] Schmutzler and co‐workers attempted to synthesize P(tmg) 3 via several reaction pathways, noting that the phosphine should possess extraordinary basicity. [ 25 , 26 , 27 , 28 ] Although they succeeded in isolating the P‐protonated form, the free phosphine P(tmg) 3 could not be liberated. In further studies, the same group prepared a series of phosphines with one and two tmg substituents and investigated their ligand properties.…”

Section: Introductionmentioning

confidence: 99%

Tris(tetramethylguanidinyl)phosphine: The Simplest Non‐ionic Phosphorus Superbase and Strongly Donating Phosphine Ligand

Buß

Röthel

Werra

et al. 2021

Chemistry A European J

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We report the synthesis and properties of the much sought-after tris(1,1,3,3-tetramethylguanidinyl) phosphine P(tmg) 3 , a crystalline, superbasic phosphine accessible through a short and scalable procedure from the cheap and commercially available bulk chemicals 1,1,3,3-tetramethylguanidine, tris(dimethylamino)-phosphine and phosphorus trichloride. The new phosphine exhibits exceptional electron donor properties and readily forms transition metal complexes with gold(I), palladium(II) and rhodium(I) precursors. The formation of zwitterionic Lewis base adducts with carbon dioxide and sulfur dioxide was explored. In addition, the complete series of phosphine chalcogenides was prepared from the reaction of P(tmg) 3 with N 2 O and the elemental chalcogens.

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“…[12] Schmutzler et al attempted to synthesize ap otentially very basic tris(tetramethylguanidino)phosphine.They were able to isolate the P-protonated form, but deprotonation leads to disintegration of this PR 3 derivative. [13] In 2017 Dielmann et al solved the problem of guanidine degradation by using related aromatically stabilized imidazolin-2-ylidenamino substituents to access the very interesting class of electron-rich imidazolin-2-ylidenaminophosphine (IAP) ligands with their high basicity as well as outstanding Tolman electronic parameters (TEPs) and large cone angles. [14] Here we report that Schwesingersp hosphazenes,t he currently strongest known non-ionic superbases,s urprisingly become even more basic, when formally the nitrene tBuN unit at the P V imine is reductively eliminated.…”

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confidence: 99%

Phosphazenyl Phosphines: The Most Electron‐Rich Uncharged Phosphorus Brønsted and Lewis Bases

2019

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It was discovered that phosphazenyl phosphines (PAPs) can be stronger P-superbases than the corresponding Schwesinger type phosphazene N-superbases.Asimple synthetic access to this class of PR 3 derivatives including their homologization is described. XRD structures,proton affinities (PA), and gas-phase basicities (GB) as well as calculated and experimental pK BH þ values in THF are presented. In contrast to their N-basic counterparts,P APs are also privileged ligands in transition metal chemistry.I nf act, they are currently the strongest unchargedP-donors known, exceeding classical and more recently discovered ligands such as PtBu 3 and imidazolin-2-ylidenaminophosphines (IAPs) with respect to their low Tolman electronic parameters (TEPs) and large cone angles.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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Synthesis and Structure of Tetraorganoguanidinyl-Substituted Phosphorus-Halogen Compounds and of Tris-N-(N′,n′,n″,n″-Tetramethyl) Guanidinyl-Phosphonium Salts

Cited by 22 publications

References 18 publications

Guanidinophosphazenes: Design, Synthesis, and Basicity in THF and in the Gas Phase

Guanidinophosphazenes: Design, Synthesis, and Basicity in THF and in the Gas Phase

Tris(tetramethylguanidinyl)phosphine: The Simplest Non‐ionic Phosphorus Superbase and Strongly Donating Phosphine Ligand

Phosphazenyl Phosphines: The Most Electron‐Rich Uncharged Phosphorus Brønsted and Lewis Bases

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