Phosphaethynolate

Last updated

The phosphaethynolate anion , also referred to as PCO, is the phosphorus-containing analogue of the cyanate anion with the chemical formula [PCO]− or [OCP]−. [1] The anion has a linear geometry and is commonly isolated as a salt. When used as a ligand, the phosphaethynolate anion is ambidentate in nature meaning it forms complexes by coordinating via either the phosphorus or oxygen atoms. [1] [2] [3] This versatile character of the anion has allowed it to be incorporated into many transition metal and actinide complexes but now the focus of the research around phosphaethynolate has turned to utilising the anion as a synthetic building block to organophosphanes. [3] [4]

Contents

Synthesis

The first reported synthesis and characterisation of phosphaethynolate came from Becker et al. in 1992. [5] They were able to isolate the anion as a lithium salt (in 87% yield) by reacting lithium bis(trimethylsilyl)phosphide with dimethyl carbonate (see Scheme 1). [5] [6] The x-ray crystallographic analysis of the anion determined the P−C bond length to be 1.555  Å (indicative of a phosphorus-carbon triple bond) and the C−O bond length to be 1.198 Å. [7] Similar studies were performed on derivatives of this structure and the results indicated that dimerisation to form a four-membered Li ring is favoured by this molecule. [5]

.mw-parser-output .vanchor>:target~.vanchor-text{background-color:#b1d2ff} Scheme 1: Becker's synthesis of the lithium salt of PCO from 1992. Becker et al. synthesis of PCO.png
Scheme 1: Becker's synthesis of the lithium salt of PCO from 1992.

Ten years later, in 2002, Westerhausen et al. published the use of Becker's method to make a family of alkaline earth metal salts of PCO (see Scheme 2); this work involved the synthesis of the magnesium, calcium, strontium and barium bis-phosphaethynolates. [5] [8] Like the salts previously reported by Becker, the alkali-earth metal analogues were unstable to moisture and air and thus were required to be stored at low temperatures (around −20 °C) in dimethoxyethane solutions. [5] [6] [8]

Scheme 2: Westerhausen's synthesis of the alkaline earth salts of PCO from 2002. Westerhausen et al. synthesis of PCO.png
Scheme 2: Westerhausen's synthesis of the alkaline earth salts of PCO from 2002.

It was not until 2011 that the first stable salt of the phosphaethynolate anion was reported by Grutzmacher and co-workers (see Scheme 3). [9] They managed to isolate the compound as a brown solid in 28% yield. [9] The structure of the stable sodium salt, formed by carbonylation of sodium phosphide, contains bridging PCO units in contrast to the terminal anions found in the previously reported structures. [9] The authors noted that this sodium salt could be handled in air as well as water without major decomposition; this emphasises the significance of the accompanying counter cation in stabilisation of PCO. [6] [9]

Scheme 3: Grutzmacher's synthesis of the sodium salt of PCO from 2011. Grutzmaker et al. synthesis of PCO.png
Scheme 3: Grutzmacher's synthesis of the sodium salt of PCO from 2011.

Direct carbonylation was a method also employed by Goicoechea in 2013 in order to synthesis a phosphaethynolate anion stabilised by a potassium cation sequestered in 18-crown-6 (see Scheme 4). [10] This method required the carbonylation of solutions of K3P7 at 150 °C and produced by-products that were readily separated during aqueous work ups. The use of aqueous work ups reflects the high stability of the salt in water. [6] [10] This method afforded the PCO anion in reasonable yields around 43%. Characterisation of the compound involved infra-red spectroscopy; the band indicative of the P≡C triple bond stretch was observed at 1730  cm−1 . [10]

Scheme 4: Goicoechea's synthesis of the potassium stabilised salt of PCO from 2013. Goicoechea et al. synthesis of PCO.png
Scheme 4: Goicoechea's synthesis of the potassium stabilised salt of PCO from 2013.

Ambidentate nature of the anion

Figure 1: The different resonance forms of the NCO and PCO anions. The values were calculated with B3LYP functional and aug-cc-pVTZ basis set using NBO/NRT analysis in GAMESS. The resonance forms (and weights) of the NCO and PCO anions.png
Figure 1: The different resonance forms of the NCO and PCO anions. The values were calculated with B3LYP functional and aug-cc-pVTZ basis set using NBO/NRT analysis in GAMESS.

The phosphaethynolate anion is the heavier isoelectronic congener of the cyanate anion. It has been shown that it behaves in a similar way to its lighter analogue, as an ambidentate nucleophile. [3] This ambidentate character of the anion means that it is able to bind via both the phosphorus and oxygen atoms depending on the nature of the centre being coordinated. [3]

Computational studies carried out on the anion such as Natural Bond Orbital (NBO) and Natural Resonance Theory (NRT) analyses can go part way to explain why PCO can react in such a manner (Figure 1). [11] The two dominant resonance forms of the phosphaethynolate anion localise negative charge on either the phosphorus or oxygen atoms meaning both are sites of nucleophilicity. [11] The same applies for the cyanate anion hence why PCO is observed to have similar pseudo-halogenic behaviour. [3] [12]

Attack by oxygen

Figure 2: Reactions of the PCO anion which depict its ambidentate nature. The ambidentate nature of the PCO anion.png
Figure 2: Reactions of the PCO anion which depict its ambidentate nature.

Coordination via the oxygen atom is favoured by hard, highly electropositive centres. [6] This is due to the fact that oxygen is a more electronegative atom and thus prefers to bind via more ionic interactions. [6] Examples of this type of coordination were presented in the work of Arnold et al. from 2015. [2] The group found that actinide complexes of PCO involving uranium and thorium both coordinated through the oxygen. This is the result of the contracted nature of the actinide orbitals which makes the metal centres more 'core-like' thus favouring ionic interactions. [2]

Attack by phosphorus

On the other hand, softer, more polarisable centres prefer to coordinate in a more covalent manner through the phosphorus atom. [6] Examples of this include complexes accommodating a neutral or sparsely charged transition metal centre. [12] [13] The first example of this nature of PCO binding was published by Grutzmacher and co-workers in 2012. [12] The group's studies used a Re(I) complex and the analysis of its bonding parameters and electronic structure showed that the phosphaethynolate anion coordinated in a bent fashion. [12] This suggested the Re(I) – P bond possessed a highly covalent character thus the complex would be best described as a metallaphosphaketene. [12] It wasn't until four years later that a second example of this coordination nature of PCO was identified. This time it came in the form of a W(0) pentacarbonyl complex produced by the Goicoechea group. [13]

Figure 3: The HOMO and LUMO of the PCO anion; surfaces calculated with the B3LYP functional and aug-cc-pVTZ basis set using Molden and GAMESS. From left to right, the atoms are P, C and O. The HOMO and LUMO of the PCO anion.png
Figure 3: The HOMO and LUMO of the PCO anion; surfaces calculated with the B3LYP functional and aug-cc-pVTZ basis set using Molden and GAMESS. From left to right, the atoms are P, C and O.

Rearrangement of coordination character

There is one particular reaction studied by Grutzmacher et al. that exhibits the rearrangement of coordination character of PCO. [3] Initially when reacting the anion with triorganyl silicon compounds, it binds via the oxygen forming the kinetic oxyphosphaalkyne product. [3] The thermodynamic silyl phosphaketene product is generated when the kinetic product rearranges to allow PCO to coordinate through phosphorus. [3]

The formation of the kinetic product is charged controlled and thus explains why it is formed by oxygen coordination. [3] The oxygen atom favours a larger degree of ionic interactions as a result of its greater electronegativity. Contrastingly, the thermodynamic product of the reaction is generated under orbital control. [3] This comes in the form of phosphorus coordination as the largest contribution in the HOMO of the anion resides on the phosphorus atom; this is clearly visible in Figure 3. [3] [11] [14]

Reactivity of the anion

Extensive studies involving the phosphaethynolate anion have shown that it can react in a variety of ways. It has documented use in cycloadditions, as a phosphorus transfer agent, a synthetic building block and as pseudo halide ligands (as described above).

Phosphorus transfer agents

In these types of reactions, CO is released as the phosphaethynolate anion acts as either a mild nucleophilic source of phosphorus or a Brønsted base. Examples of these types of reactions involving PCO include work conducted by Grutzmacher and Goicoechea. [15] [16]

In 2014, Grutzmacher et al. reported that an imidazolium salt would react with the phosphaethynolate anion to produce a phosphinidine carbene adduct. [1] [15] Computational mechanistic studies were conducted on this reaction using density functional theory at the B3LYP/6-31+G* level. [15] The results of these investigations suggested that the lowest energy and therefore most likely pathway involves PCO acting as a Brønsted base initially deprotonating the acidic imidazolium cation to generate the intermediate phosphaketene, HPCO. [1] [15] [17] The highly unstable protonated PCO remains hydrogen bonded to the newly produced N-heterocylic carbene prior to rearrangement and formation of the observed product. [6] [15] In this case, PCO does not act as a mild nucleophile due to the augmented stability of the starting imidazolium cation. [15]

On the other hand, in the work published by Goicoechea and co-workers in 2015, the phosphaethynolate anion can be seen to act as a source of nucleophilic phosphide (P−). [16] The anion was seen to add across the Si=Si double bond of cyclotrisilene thus introducing a phosphorus vertex into its scaffold (after undergoing decarbonylation). [16]

Figure 4: The different reaction pathways of the PCO anion. Reactivity of the PCO anion.png
Figure 4: The different reaction pathways of the PCO anion.

Cycloaddition Reagents

After synthesising the potassium salt of the phosphaethynolate anion in 2013, Goicoechea et al. began to look into the potential of PCO towards cycloadditions. [10] They found that the anion could react in a [2+2] fashion with a diphenyl ketene to produce the first isolatable example of a four-membered monoanionic phosphorus containing heterocycle. [1] [10] They employed the same method to test other unsaturated substrates such as carbodiimides and found that the likelihood of cyclisation heavily relies on the nature of the substituents on the unsaturated substrate. [10]

Cycloaddition reactions involving the phosphaethynolate anion have also been shown by Grutzmacher and co-workers to be a viable synthetic route to other heterocycles. [18] One simple example is the reaction between the NaPCO and an α-pyrone. This reaction yields the sodium phosphinin-2-olate salt which is stable to both air and moisture. [1] [18]

Synthetic building blocks

A large part of the research involving PCO is now looking into utilising the anion as a synthetic building block to derive phosphorus containing analogues of small molecules.

The first major breakthrough in this area came from Goicoechea et al. in 2013; they published the reaction between the PCO anion and ammonium salts which yielded the phosphorus containing analogue of urea in which phosphorus replaces a nitrogen atom. [4] The group predict that this heavier congener could have applications in new materials, anion sensing and coordination chemistry. [4]

Goicoechea and co-workers were also able to isolate the heavily sought after phosphorus containing analogue of isocyanic acid, HPCO, in 2017. [17] This molecule is thought to be a crucial intermediate in a lot of reactions involving PCO (including P-transfer to an imidazolium cation). [6] [17]

Moreover, the most recent addition to this class of small molecules is the phosphorus containing analogue of N,N-dimethylformamide. [19] This work in which the phosphorus again replaces a nitrogen atom was published in 2018 by Stephan and co-workers. [19] Generating acylphosphines in this manner is considered a much milder route than other current strategies that require multi-step syntheses involving toxic, volatile and pyrophoric reagents. [19]

Other analogues

The other analogues of the phosphaethynolate anion all obey the general formulae E-C-X and are made by varying E and X. When changing either atom, unique trends amongst the different analogues become apparent.

Figure 5: The different resonance forms and weights of the different ECX analogues. The values were calculated with B3LYP functional and aug-cc-pVTZ basis set using NBO/NRT analysis in GAMESS. Resonance forms of the NCO, PCO and AsCO anions.png
Figure 5: The different resonance forms and weights of the different ECX analogues. The values were calculated with B3LYP functional and aug-cc-pVTZ basis set using NBO/NRT analysis in GAMESS.

Varying E

As 'E' is varied by descending group 15, there is a clear shift in the weights of the resonance structures towards the phosphaketene analogue (Figure 5). [11] This reflects the decrease in effective orbital overlap between E and C which in turn disfavours multiple bond formation. This increasing tendency to form double and not triple E-C bonds is also reflected in calculated E-C bond lengths (Table 1). [14] The data from Table 1 is evidence of E-C bond elongation which correlates with the change from triple to double bond. [7]

Table 1: E-C bond lengths and delocalisation energies of the different ECO analgoues, the values were calculated with B3LYP functional and aug-cc-pVTZ basis set in GAMESS. Bond lengths taken from cited literature. [14]
ECOE−C bond length (Å)Delocalisation energy (kcal/mol)
NCO1.19241.0
PCO1.62744.0
AsCO1.74064.0

In addition, NBO analysis highlights that the greatest electron delocalisation within the anions stems from the donation of an oxygen lone pair into the E−C π antibonding orbital. The energy value associated with this donation is seen to increase down the group (Table 1). This explains the increasing resonance weight towards the ketene like isomer as populating antibonding orbitals usually suggests the breaking of a bond. [11]

The shift towards the ketene isomer will also cause an increase in charge density on the elemental 'E' atom; this makes the elemental atom an increasing source of nucleophilicity (see Figure 5 and Figure 6). [11]

Figure 6: Stacked graph of Laplacian electron density of the PCO anion. Graph plotted in Multiwfn using the results of AIMS analysis from Molden and GAMESS. From left to right, the atoms are P, C and O. The laplacian electron density of the PCO anion.png
Figure 6: Stacked graph of Laplacian electron density of the PCO anion. Graph plotted in Multiwfn using the results of AIMS analysis from Molden and GAMESS. From left to right, the atoms are P, C and O.

Varying X

Figure 7: Contour plot of the Laplacian electron density of the PCO anion. Graph plotted in Multiwfn using the results of AIMS analysis from Molden and GAMESS. From top to bottom, the atoms are O, C and P. PCO laplacian electron density contour plot.png
Figure 7: Contour plot of the Laplacian electron density of the PCO anion. Graph plotted in Multiwfn using the results of AIMS analysis from Molden and GAMESS. From top to bottom, the atoms are O, C and P.
Figure 8: Contour plot of the Laplacian electron density of the PCS anion. Graph plotted in Multiwfn using the results of AIMS analysis from Molden and GAMESS. From top to bottom, the atoms are S, C and P. PCS laplacian electron density contour plot.png
Figure 8: Contour plot of the Laplacian electron density of the PCS anion. Graph plotted in Multiwfn using the results of AIMS analysis from Molden and GAMESS. From top to bottom, the atoms are S, C and P.
Table 2: Resonance weights of the PCX analogues, the values were calculated with B3LYP functional and aug-cc-pVTZ basis set in GAMESS. [11]
PCXResonance 'A' weightResonance 'B' weight
PCO51.5%38.4%
PCS57.9%24.2%

The simplest analogue that can be formed as 'X' is varied is PCS−. This anion was first isolated by Becker et al. by reacting the phosphaethynolate anion with carbon disulphide. [20] Unlike PCO, PCS shows ambidentate nucleophilic tendencies towards the W(0) complex mentioned above. [11]

This is the result of a reduced difference in electronegativity between E and X thus neither atom offers a substantial advantage over the other in terms of providing ionic contributions to bonding. As a result, the average electron density in PCS is spread over the entire anion (Figure 8) whereas in PCO, most electron density is localised on the phosphorus atom (Figure 7) as this is the atom which bonds to form the thermodynamically favourable product. [11]

Related Research Articles

In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are Lewis bases.

<span class="mw-page-title-main">Cyanate</span> Anion with formula OCN and charge –1

The cyanate ion is an anion with the chemical formula OCN−. It is a resonance of three forms: [O−−C≡N] (61%) ↔ [O=C=N−] (30%) ↔ [O+≡C−N2−] (4%).

<span class="mw-page-title-main">Organoboron chemistry</span> Study of compounds containing a boron-carbon bond

Organoboron chemistry or organoborane chemistry studies organoboron compounds, also called organoboranes. These chemical compounds combine boron and carbon; typically, they are organic derivatives of borane (BH3), as in the trialkyl boranes.

<span class="mw-page-title-main">Phosphaalkyne</span>

In chemistry, a phosphaalkyne is an organophosphorus compound containing a triple bond between phosphorus and carbon with the general formula R-C≡P. Phosphaalkynes are the heavier congeners of nitriles, though, due to the similar electronegativities of phosphorus and carbon, possess reactivity patterns reminiscent of alkynes. Due to their high reactivity, phosphaalkynes are not found naturally on earth, but the simplest phosphaalkyne, phosphaethyne (H-C≡P) has been observed in the interstellar medium.

<span class="mw-page-title-main">Persistent carbene</span> Type of carbene demonstrating particular stability

A persistent carbene (also known as stable carbene) is a type of carbene demonstrating particular stability. The best-known examples and by far largest subgroup are the N-heterocyclic carbenes (NHC) (sometimes called Arduengo carbenes), for example diaminocarbenes with the general formula (R2N)2C:, where the four R moieties are typically alkyl and aryl groups. The groups can be linked to give heterocyclic carbenes, such as those derived from imidazole, imidazoline, thiazole or triazole.

In organic chemistry, umpolung or polarity inversion is the chemical modification of a functional group with the aim of the reversal of polarity of that group. This modification allows secondary reactions of this functional group that would otherwise not be possible. The concept was introduced by D. Seebach and E.J. Corey. Polarity analysis during retrosynthetic analysis tells a chemist when umpolung tactics are required to synthesize a target molecule.

Organophosphines are organophosphorus compounds with the formula PRnH3−n, where R is an organic substituent. These compounds can be classified according to the value of n: primary phosphines (n = 1), secondary phosphines (n = 2), tertiary phosphines (n = 3). All adopt pyramidal structures. Organophosphines are generally colorless, lipophilic liquids or solids. The parent of the organophosphines is phosphine (PH3).

The total synthesis of quinine, a naturally-occurring antimalarial drug, was developed over a 150-year period. The development of synthetic quinine is considered a milestone in organic chemistry although it has never been produced industrially as a substitute for natural occurring quinine. The subject has also been attended with some controversy: Gilbert Stork published the first stereoselective total synthesis of quinine in 2001, meanwhile shedding doubt on the earlier claim by Robert Burns Woodward and William Doering in 1944, claiming that the final steps required to convert their last synthetic intermediate, quinotoxine, into quinine would not have worked had Woodward and Doering attempted to perform the experiment. A 2001 editorial published in Chemical & Engineering News sided with Stork, but the controversy was eventually laid to rest once and for all when Williams and coworkers successfully repeated Woodward's proposed conversion of quinotoxine to quinine in 2007.

Thiophosphates (or phosphorothioates, PS) are chemical compounds and anions with the general chemical formula PS
4−xO3−
x (x = 0, 1, 2, or 3) and related derivatives where organic groups are attached to one or more O or S. Thiophosphates feature tetrahedral phosphorus(V) centers.

Methylidynephosphane (phosphaethyne) is a chemical compound which was the first phosphaalkyne compound discovered, containing the unusual C≡P carbon-phosphorus triple bond.

<span class="mw-page-title-main">Cyaphide</span>

Cyaphide, P≡C−, is the phosphorus analogue of cyanide. It is not known as a discrete salt, however in silico measurements reveal that the −1 charge in this ion is located mainly on carbon (0.65), as opposed to phosphorus.

<span class="mw-page-title-main">Nontrigonal pnictogen compounds</span>

Nontrigonal pnictogen compounds refer to tricoordinate trivalent pnictogen compounds that are not of typical trigonal pyramidal molecular geometry. By virtue of their geometric constraint, these compounds exhibit distinct electronic structures and reactivities, which bestow on them potential to provide unique nonmetal platforms for bond cleavage reactions.

Aluminium(I) nucleophiles are a group of inorganic and organometallic nucleophilic compounds containing at least one aluminium metal center in the +1 oxidation state with a lone pair of electrons strongly localized on the aluminium(I) center.

An arsinide, arsanide, dihydridoarsenate(1−) or arsanyl compound is a chemical derivative of arsine, where one hydrogen atom is replaced with a metal or cation. The arsinide ion has formula AsH−2. It can be considered as a ligand with name arsenido or arsanido. Researchers are unenthusiastic about studying arsanyl compounds, because of the toxic chemicals, and their instability. The IUPAC names are arsanide and dihydridoarsenate(1−). For the ligand the name is arsanido. The neutral −AsH2 group is termed arsanyl.

<span class="mw-page-title-main">Carbones</span> Class of molecules

Carbones are a class of molecules containing a carbon atom in the 1D excited state with a formal oxidation state of zero where all four valence electrons exist as unbonded lone pairs. These carbon-based compounds are of the formula CL2 where L is a strongly σ-donating ligand, typically a phosphine (carbodiphosphoranes) or a N-heterocyclic carbene/NHC (carbodicarbenes), that stabilises the central carbon atom through donor-acceptor bonds. Carbones possess high-energy orbitals with both σ- and π-symmetry, making them strong Lewis bases and strong π-backdonor substituents. Carbones possess high proton affinities and are strong nucleophiles which allows them to function as ligands in a variety of main group and transition metal complexes. Carbone-coordinated elements also exhibit a variety of different reactivities and catalyse various organic and main group reactions.  

<span class="mw-page-title-main">Stable phosphorus radicals</span>

Stable and persistent phosphorus radicals are phosphorus-centred radicals that are isolable and can exist for at least short periods of time. Radicals consisting of main group elements are often very reactive and undergo uncontrollable reactions, notably dimerization and polymerization. The common strategies for stabilising these phosphorus radicals usually include the delocalisation of the unpaired electron over a pi system or nearby electronegative atoms, and kinetic stabilisation with bulky ligands. Stable and persistent phosphorus radicals can be classified into three categories: neutral, cationic, and anionic radicals. Each of these classes involve various sub-classes, with neutral phosphorus radicals being the most extensively studied. Phosphorus exists as one isotope 31P (I = 1/2) with large hyperfine couplings relative to other spin active nuclei, making phosphorus radicals particularly attractive for spin-labelling experiments.

Heteroatomic multiple bonding between group 13 and group 15 elements are of great interest in synthetic chemistry due to their isoelectronicity with C-C multiple bonds. Nevertheless, the difference of electronegativity between group 13 and 15 leads to different character of bondings comparing to C-C multiple bonds. Because of the ineffective overlap between p𝝅 orbitals and the inherent lewis acidity/basicity of group 13/15 elements, the synthesis of compounds containing such multiple bonds is challenging and subject to oligomerization. The most common example of compounds with 13/15 group multiple bonds are those with B=N units. The boron-nitrogen-hydride compounds are candidates for hydrogen storage. In contrast, multiple bonding between aluminium and nitrogen Al=N, Gallium and nitrogen (Ga=N), boron and phosphorus (B=P), or boron and arsenic (B=As) are less common.

<span class="mw-page-title-main">Cyaarside</span> Chemical compound

Cyaarside, also called cyarside, is the As≡C− anion. Featuring a triple bond between arsenic and carbon, it is the arsenic analogue of cyanide and cyaphide.

A ketenyl anion contains a C=C=O allene-like functional group, similar to ketene, with a negative charge on either terminal carbon or oxygen atom, forming resonance structures by moving a lone pair of electrons on C-C-O bond. Ketenes have been sources for many organic compounds with its reactivity despite a challenge to isolate them as crystal. Precedent method to obtain this product has been at gas phase or at reactive intermediate, and synthesis of ketene is used be done in extreme conditions. Recently found stabilized ketenyl anions become easier to prepare compared to precedent synthetic procedure. A major feature about stabilized ketene is that it can be prepared from carbon monoxide (CO) reacting with main-group starting materials such as ylides, silylene, and phosphinidene to synthesize and isolate for further steps. As CO becomes a more common carbon source for various type of synthesis, this recent finding about stabilizing ketene with main-group elements opens a variety of synthetic routes to target desired products.

<span class="mw-page-title-main">Aluminylene</span>

Aluminylenes are a sub-class of aluminium(I) compounds that feature singly-coordinated aluminium atoms with a lone pair of electrons. As aluminylenes exhibit two unoccupied orbitals, they are not strictly aluminium analogues of carbenes until stabilized by a Lewis base to form aluminium(I) nucleophiles. The lone pair and two empty orbitals on the aluminium allow for ambiphilic bonding where the aluminylene can act as both an electrophile and a nucleophile. Aluminylenes have also been reported under the names alumylenes and alanediyl.

References

  1. 1 2 3 4 5 6 Quan, Z. J. and Wang, X. C. (2014) 'The 2-phosphaethynolate anion: Convenient synthesis and the reactivity', Organic Chemistry Frontiers. doi:10.1039/c4qo00189c.
  2. 1 2 3 Camp, C., Settineri, N., Lefèvre, J., Jupp, A. R., Goicoechea, J. M., Maron, L. and Arnold, J. (2015) 'Uranium and thorium complexes of the phosphaethynolate ion', Chemical Science. doi: 10.1039/c5sc02150b.
  3. 1 2 3 4 5 6 7 8 9 10 11 Heift, D., Benko, Z. and Grützmacher, H. (2014) 'Is the phosphaethynolate anion, (OCP)-, an ambident nucleophile? A spectroscopic and computational study', Dalton Transactions. doi: 10.1039/c3dt53569j.
  4. 1 2 3 Jupp, A. R., and Goicoechea, J. M. (2013) 'Phosphinecarboxamide: A Phosphorus-Containing Analogue of Urea and Stable Primary Phosphine', J. Am. Chem. Soc.. DOI:10.1021/ja4115693.
  5. 1 2 3 4 5 6 Becker, G., Schwarz, W., Seidler, N. and Westerhausen, M. (1992) 'Acyl‐ und Alkylidenphosphane. XXXIII. Lithoxy‐methylidenphosphan · DME und ‐methylidinphosphan · 2 DME — Synthese und Struktur', ZAAC ‐ Journal of Inorganic and General Chemistry. doi: 10.1002/zaac.19926120113.
  6. 1 2 3 4 5 6 7 8 9 10 11 Grutzmacher, H., and Goicoechea, J. (2018) 'The chemistry of the 2‐phosphaethynolate anion', Angew. Chem. Int. Ed. doi:10.1002/anie.201803888.
  7. 1 2 3 4 Pyykkö, P. (2015) 'Additive covalent radii for single-, double-, and triple-bonded molecules and tetrahedrally bonded crystals: A summary', Journal of Physical Chemistry A. doi: 10.1021/jp5065819.
  8. 1 2 3 Westerhausen, M., Schneiderbauer, S., Piotrowski, H., Suter, M. and Nöth, H. (2002) 'Synthesis of alkaline earth metal bis(2-phosphaethynolates)', Journal of Organometalic Chemistry. doi: 10.1016/S0022-328X(01)01267-0.
  9. 1 2 3 4 5 Puschmann, F. F., Stein, D., Heift, D., Hendriksen, C., Gal, Z. A., Grützmacher, H. F. and Grützmacher, H. (2011) 'Phosphination of carbon monoxide: A simple synthesis of sodium phosphaethynolate (NaOCP)', Angewandte Chemie - International Edition. doi: 10.1002/anie.201102930.
  10. 1 2 3 4 5 6 7 Jupp, A. R. and Goicoechea, J. M. (2013) 'The 2-phosphaethynolate anion: A convenient synthesis and [2+2] cycloaddition chemistry', Angewandte Chemie - International Edition. doi: 10.1002/anie.201305235.
  11. 1 2 3 4 5 6 7 8 9 10 11 12 Hou, G. L., Chen, B., Transue, W. J., Yang, Z., Grützmacher, H., Driess, M., Cummins, C. C., Borden, W. T. and Wang, X. Bin (2017) 'Spectroscopic Characterization, Computational Investigation, and Comparisons of ECX-(E = As, P, and N; X = S and O) Anions', Journal of the American Chemical Society. doi: 10.1021/jacs.7b02984.
  12. 1 2 3 4 5 Alidori, S., Heift, D., Santiso-Quinones, G., Benkå, Z., Grützmacher, H., Caporali, M., Gonsalvi, L., Rossin, A. and Peruzzini, M. (2012) 'Synthesis and characterization of terminal [Re(XCO)(CO) 2(triphos)] (X=N, P): Isocyanate versus phosphaethynolate complexes', Chemistry - A European Journal. doi: 10.1002/chem.201202590.
  13. 1 2 Jupp, A. R., Geeson, M. B., McGrady, J. E. and Goicoechea, J. M. (2016) 'Ambient-Temperature Synthesis of 2-Phosphathioethynolate, PCS-, and the Ligand Properties of ECX-(E = N, P; X = O, S)', European Journal of Inorganic Chemistry. doi: 10.1002/ejic.201501075.
  14. 1 2 3 Lu, Y., Wang, H., Xie, Y., Liu, H. and Schaefer, H. F. (2014) 'The cyanate and 2-phosphaethynolate anion congeners ECO-(E = N, P, As, Sb, Bi): Prelude to experimental characterization', Inorganic Chemistry. doi: 10.1021/ic500780h.
  15. 1 2 3 4 5 6 Tondreau, A. M., Benko, Z., Harmer, J. R. and Grützmacher, H. (2014) 'Sodium phosphaethynolate, Na(OCP), as a “p” transfer reagent for the synthesis of N-heterocyclic carbene supported P3 and PAsP radicals', Chemical Science. doi: 10.1039/c3sc53140f.
  16. 1 2 3 Robinson, T. P., Cowley, M. J., Scheschkewitz, D. and Goicoechea, J. M. (2015) 'Phosphide delivery to a cyclotrisilene', Angewandte Chemie - International Edition. doi: 10.1002/anie.201409908.
  17. 1 2 3 Hinz, A., Labbow, R., Rennick, C., Schulz, A. and Goicoechea, J. M. (2017) 'HPCO—A Phosphorus-Containing Analogue of Isocyanic Acid', Angewandte Chemie - International Edition. doi: 10.1002/anie.201700368.
  18. 1 2 Chen, X., Alidori, S., Puschmann, F. F., Santiso-Quinones, G., Benko, Z., Li, Z., Becker, G., Grützmacher, H. F. and Grützmacher, H. (2014) 'Sodium phosphaethynolate as a building block for heterocycles', Angewandte Chemie - International Edition. doi: 10.1002/anie.201308220.
  19. 1 2 3 Szkop, K., Jupp, A. R., and Stephan, D. W. (2018) 'P,P‑Dimethylformylphosphine: The Phosphorus Analogue of N,N‑Dimethylformamide' J. Am. Chem. Soc. doi:10.1021/jacs.8b09266.
  20. ↑ Tambornino, F., Hinz, A., Köppe, R. and Goicoechea, J. M. (2018) 'A General Synthesis of Phosphorus- and Arsenic-Containing Analogues of the Thio- and Seleno-cyanate Anions', Angewandte Chemie - International Edition. doi: 10.1002/anie.201805348.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.