Phosphagallenes (1 a/1 b) featuring double bonds between phosphorus and gallium were synthesized by reaction of (phosphanyl)phosphaketenes with the gallium carbenoid Ga(Nacnac) (Nacnac=HC[C(Me)N(2,6‐i‐Pr2C6H3)]2). The stability of these species is dependent on the saturation of the phosphanyl moiety. 1 a, which bears an unsaturated phosphanyl ring, rearranges in solution to yield a spirocyclic compound (2) which contains a P=P bond. The saturated variant 1 b is stable even at elevated temperatures. 1 b behaves as a frustrated Lewis pair capable of activation of H2 and forms a 1:1 adduct with CO2.

The reactivity of the phosphanyl‐phosphagallene, [H2C{N(Dipp)}]2PP=Ga(Nacnac) (Nacnac=HC[C(Me)N(Dipp)]2; Dipp=2,6‐iPr2C6H3) towards a series of reagents possessing E−H bonds (primary amines, ammonia, water, phenylacetylene, phenylphosphine, and phenylsilane) is reported. Two contrasting reaction pathways are observed, determined by the polarity of the E−H bonds of the substrates. In the case of protic reagents (δ−E−Hδ+), a frustrated Lewis pair type of mechanism is operational at room temperature, in which the gallium metal centre acts as a Lewis acid and the pendant phosphanyl moiety deprotonates the substrates. Interestingly, at elevated temperatures both NH2iPr and ammonia can react via a second, higher energy, pathway resulting in the hydroamination of the Ga=P bond. By contrast, with hydridic reagents (δ+E−Hδ−), such as phenylsilane, hydroelementation of the Ga=P bond is exclusively observed, in line with the polarisation of the Si−H and Ga=P bonds.

Phosphagallenes (1 a/1 b) featuring double bonds between phosphorus and gallium were synthesized by reaction of (phosphanyl)phosphaketenes with the gallium carbenoid Ga(Nacnac) (Nacnac=HC[C(Me)N(2,6‐i‐Pr2C6H3)]2). The stability of these species is dependent on the saturation of the phosphanyl moiety. 1 a, which bears an unsaturated phosphanyl ring, rearranges in solution to yield a spirocyclic compound (2) which contains a P=P bond. The saturated variant 1 b is stable even at elevated temperatures. 1 b behaves as a frustrated Lewis pair capable of activation of H2 and forms a 1:1 adduct with CO2.

Research on using H-phosphonate diesters to introduce phosphorus functionality into molecules and polymers, some of which have medicinal applications, has recently attracted a lot of attention. Deuterium labelling to yield the corresponding D-phosphonate diesters, although desirable in order to help with the mechanistic elucidation of reactions containing H-phosphonate diesters, has been demonstrated to be a challenge. Deuterium exchange at Hphosphonate diesters using D 2 O, MeOD and ND 2 Bn has shown competitive behavior with hydrolysis, alcoholysis and aminolysis reactions, respectively. This facile substituent exchange for the addition of D 2 O and MeOD can be attributed to the similar energy required to eliminate ROH or H 2 O (ROD or HOD, R = iPr, Et, Me) from a pentavalent P(V) intermediate which is generated from axial delivery of an OD or OR group from D 2 O and MeOD, respectively. The trend in reaction rate for the exchange processes follows the order of R = Me > Et > iPr in (RO) 2 P(O)H and also depends on the nucleophilicity of the incoming group. Attempted synthesis of D-phosphonate diesters directly from PCl 3 and alcohols or via lithiation reactions further demonstrated just how sensitive the H/D-scrambling process is. These results have implications for the general reactivity of H-phosphonate diesters towards water, alcohol, and amines and their potential to selectively undergo substitution at either P-OR or P-H. Moreover, insight into the mechanism(s) of selective deuterium exchange, for example to give D-phosphonate diesters via the direct exchange of D for H, was illuminated through this research. at 101 MHz and are given in parts per million relative to CDCl 3 (δ = 77.0 ppm). Chemical shifts for 31 P NMR spectra are recorded at 161.97 MHz and given relative to external 85% phosphoric acid (δ = 0 ppm). Data are represented as follows: chemical shift, multiplicity (app = apparent, br = broad, s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet), coupling constants in Hertz (Hz), and integration.

The reactivity of the phosphanyl‐phosphagallene, [H2C{N(Dipp)}]2PP=Ga(Nacnac) (Nacnac=HC[C(Me)N(Dipp)]2; Dipp=2,6‐iPr2C6H3) towards a series of reagents possessing E−H bonds (primary amines, ammonia, water, phenylacetylene, phenylphosphine, and phenylsilane) is reported. Two contrasting reaction pathways are observed, determined by the polarity of the E−H bonds of the substrates. In the case of protic reagents (δ−E−Hδ+), a frustrated Lewis pair type of mechanism is operational at room temperature, in which the gallium metal centre acts as a Lewis acid and the pendant phosphanyl moiety deprotonates the substrates. Interestingly, at elevated temperatures both NH2iPr and ammonia can react via a second, higher energy, pathway resulting in the hydroamination of the Ga=P bond. By contrast, with hydridic reagents (δ+E−Hδ−), such as phenylsilane, hydroelementation of the Ga=P bond is exclusively observed, in line with the polarisation of the Si−H and Ga=P bonds.

A series of ammonium monosubstituted H‐phosphonate salts were synthesized by combining H‐phosphonate diesters with amines in the absence of solvent at 80 °C. Variation of the ester substituent and amine produced a range of ionic liquids with low melting points. The products and by‐products were analyzed by spectroscopic and spectrometric techniques in order to get a better mechanistic picture of the dealkylation and formal dearylation observed. For dialkyl H‐phosphonate diesters, (RO)2P(O)H (R=alkyl), the reaction proceeds via direct dealkylation with the reactivity increasing in the order R=iPr<Et<Me corresponding to DFT calculated activation enthalpies of 22.6, 20.8, and 17.9 kcal mol−1. For the diphenyl H‐phosphonate diesters, (PhO)2P(O)H, the dearylation was found to proceed via phenol‐assisted formation of a 5‐coordinate intermediate, (PhO)3PH(OH), from which P(OPh)3 and water were eliminated. The presence of an equivalent of water then facilitated the formation of P(OH)2OPh and the amine, R'NH2, subsequently abstracted a proton from it to yield [(PhO)PH(O)O]‐[R'NH3]+.

Dedicated to Professor Cameron Jones on the occasion of his 60 th birthday.The synthesis of group 10 metal complexes bearing a phosphanyl-phosphinidene ligand, [(H 2 C) 2 (NDipp) 2 ]P=P (Dipp = 2,6-di-iso-propylphenyl), is reported. These compounds can be accessed by the decarbonylation of a phosphanyl-phosphaketene with metal nucleophiles including M(P t Bu 3 ) 2 (M = Pt, Pd) and Ni(COD){[C(NMes)(CH) 2 N] 2 CH 2 }.

In this study, the step‐wise synthesis to a series of higher phosphoramidates was explored, affording compounds containing N−P−N, symmetric and asymmetric P−N−P and P−N−P−N−P linkages. Salt elimination and lithiation strategies were employed to create the new P−N bonds. It was found that the steric bulk and electronic contribution of the substituents on the P(V) centers were important factors to the success of the reactions. The oligomeric phosphoramidates were characterized by multinuclear NMR and IR spectroscopies as well as ESI mass spectrometry. A selection of the synthesized P−N oligomers were evaluated for their antimicrobial activity against E.coli, S.aureus, C.albicans, and A.fumigatus at varying concentrations. The results suggest their potential use as environmentally friendly fire retardants as the minimal inhibitory concentration (MIC) value for all the compounds was found to be >128 μM, indicating that the compounds do not have any detectable antimicrobial activity.