Synthesis and Structure of K+[iPrNCP]-, a 1-Aza-3λ3-phospha-3-allenide

Becker, Gerd; Brombach, H.; Horner, Stephen Thomas; Niecke, Edgar; Schwarz, W.; Streubel, Rainer; Würthwein, Ernst‐Ulrich

doi:10.1021/ic048162+

Cited by 25 publications

(21 citation statements)

References 49 publications

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“…While phosphaalkynes (RCP) have been known for some time,1–3 the terminal MCP has only been reported as a transient species 4. 5 Other C‐functionalized XCP compounds (X=R 3 Si,6 R 2 N,7, 8 RO,8 F,9 Cl,10), anionic species [XCP] − (X=R 3 B,11 RN,8 O,12 S13), and the cationic phosphonio phosphaalkyne [R 3 PCP] + ,14 have been synthesized, but the vast majority of reports deal with tert ‐butyl,15 adamantyl,16 2,4,6‐trimethylphenyl17 and 2,4,6‐tri‐ tert ‐butylphenyl18 phosphaalkynes. Recently, we devised a very simple method for accessing the kinetically stable crystalline triphenylmethyl (trityl)‐substituted phosphaalkyne, Ph 3 CCP ( 1 ), which allowed for the economical metal‐promoted synthesis of phosphorus heterocycles.…”

Section: Methodsmentioning

confidence: 99%

Making the True “CP” Ligand

et al. 2006

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The quest for cyaphide, the phosphorus equivalent of cyanide, has been a continuous struggle for many years. Potential applications arising from the use of C P as a bridging ligand between two metals, the incorporation of CP into coordination polymers and new materials, and the basic synthetic challenges of making C P have provided inspiration for decades. While phosphaalkynes (R À C P) have been known for some time, [1][2][3] the terminal MÀCP has only been reported as a transient species. [4,5] Other C-functionalized XÀCP compounds (X = R 3 Si, [6] R 2 N, [7,8] RO, [8] F, [9] Cl, [10] ), anionic species [XÀCP] À (X = R 3 B, [11] RN, [8] O, [12] S [13] ), and the cationic phosphonio phosphaalkyne [R 3 P À C P] + , [14] have been synthesized, but the vast majority of reports deal with tert-butyl, [15] adamantyl, [16] 2,4,6-trimethylphenyl [17] and 2,4,6-tri-tert-butylphenyl [18] phosphaalkynes. Recently, we devised a very simple method for accessing the kinetically stable crystalline triphenylmethyl (trityl)-substituted phosphaalkyne, Ph 3 CC P (1), which allowed for the economical metal-promoted synthesis of phosphorus heterocycles. However, our ultimate goal and incentive for synthesizing the trityl-substituted phosphaalkyne was to find an adequate leaving group that would lead us to cyaphide. [19] Treatment of 1 or its complexes [MH(dppe) 2 (Ph 3 C-CP)]OTf (M = Fe or Ru; dppe = bis(1,2-diphenylphosphinoethane); OTf = trifluoromethanesulfonate) with nucleophiles (Nu) did not furnish the desired cyaphide, C P À , or its complexes [Eq. (1); electrophile (E) = C].Therefore, we reasoned that silicon would be more susceptible to nucleophilic attack (E = Si) and applied an analogous synthetic procedure to access the higher homologue Ph 3 SiCP (3).Conversion of Ph 3 SiCH 2 Cl into the Grignard reagent followed by treatment with PCl 3 produced the silyl-substituted alkyl phosphonous dichloride, Ph 3 SiCH 2 PCl 2 (2), in over 87 % yield (Scheme 1). Employing 2.2 equiv of DABCO (1,8-diazabicyclo[2.2.2]octane) effected the dehydrohalogenation reaction, and 2 was fully transformed into the triphenylsilyl-substituted phosphaalkyne 3. The reaction occurred at ambient temperature and in multiple solvents in less than one hour. (In contrast, the reaction of DABCO with Ph 3 CCH 2 PCl 2 to furnish Ph 3 CC P required a 10-fold excess of base, elevated temperatures, and proceeded best in acetonitrile.[19] ) While DABCO alone was effective for the conversion of 2 into 3, we saw rapid decomposition of this new phosphaalkyne, which was dependent on the solvent. Qualitatively, the rate of decomposition of 3 followed the order Et 2 O % toluene < THF ! CH 3 CN. Suspecting that DABCO-HCl was acting as a soluble source of chloride anion in the more polar solvents that then attacked silicon to produce Ph 3 SiCl and the CP anion, which is seemingly unstable under the reaction conditions, we added AgOTf to the reaction mixture. When a solution of 2 in toluene was pretreated with 2.2 equiv of AgOTf for 5 min followed by addition of 2.2 equi...

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Section: Methodsmentioning

confidence: 99%

Making the True “CP” Ligand

et al. 2006

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“…Sodium phosphaethynolate [Na(OCP)] is an efficient and easily accessible building block and has been successfully employed in the synthesis of metal complexes and various organophosphorus compounds, especially heterocycles . Some selected examples are shown in Scheme .…”

Section: Introductionmentioning

confidence: 99%

“…[39,40] The highlyr eactive 1,2,5-azadiphosphole ADP8 has only been observeda sanintermediate in the synthesis of aza-tetraphosphaquadricyclanes, [41] but has been structurally characterizeda s al igand in an iridium complex. [35] Sodium phosphaethynolate [Na(OCP)] [42,43] is an efficient and easily accessible buildingb lock and has been successfully employedi nt he synthesis of metal complexes [44][45][46] and various organophosphorus compounds, especially heterocycles. [47][48][49][50][51] Some selectede xamples are shown in Scheme 2.…”

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confidence: 99%

A Convenient Synthesis of 1,2,4‐ and 1,3,4‐Azadiphospholes

Suter

Benkő

2016

Chemistry A European J

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A new synthetic route to functionalized neutral and anionic azadiphospholes from easily accessible starting materials is described. Equimolar reaction of Na(OCP) and N-(2,6-dimethylphenyl)pivalimidoyl chloride 2 a cleanly affords the imidoxy-functionalized 1,2,4-azadiphosphole 3 a. Using Na(OCP) and imidoyl chloride in a 2:1 ratio leads to an anionic four-membered ring Na[4 a], which has been structurally characterized. During 16 h at room temperature, Na[4 a] rearranges to the anionic 1,3,4-azadiphospholide Na[5 a] with release of carbon monoxide. Applying the more sterically demanding N-(2,6-diisopropylphenyl)pivalimidoyl chloride allows isolation of the 1,3,4-azadiphospholide Na[5 b] in good yield (>70 %). Possible mechanisms leading to the new isomeric azadiphospholides have been investigated with the aid of high-level composite calculations.

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“…In a first series of experiments Mes*PPMe 3 ( 1a ) 14 was dissolved in C 6 D 6 , and an excess of CN t Bu ( 2a ) was added ( Scheme 2 ). 20 Within 16 h at room temperature, two new signals were observed in the 31 P{ 1 H} NMR spectrum at −62.6 and −103.8 ppm, respectively, along with mostly unreacted starting materials.…”

Section: Resultsmentioning

confidence: 99%

“… 13 A trimethylstannyl substitution at the phosphorus centre in 1,3-phosphaazaallenes was achieved by reacting the potassium 1,3-azaphosphaallenide K[iPrNCP] with ClSnMe 3 in a salt metathesis reaction, thus revealing another access to this substance class. 14 The most recent examples of 1,3-phosphaazaallenes were synthesized by Bertrand et al in coupling reactions of (phosphino)phosphinidenes with isocyanides. 15 Moreover, Scheschkewitz et al showed that a phosphasilene with a mobile NMe 2 -functionality on the phosphorus atom undergoes an NMe 2 -shift in the reaction with CN t Bu to give a P-silyl-substituted 1,3-phosphaazaallene.…”

Section: Introductionmentioning

confidence: 99%