A General Strategy for Increasing the Air Stability of Phosphines Including Primary Phosphines

A general approach for increasing the air-stability of various primary phosphines in the absence of kinetic stabilization is presented that contrasts with previous interpretations, which were limited to specific phosphines. This contribution shows the synthesis of a series of air-stable primary phosphines Fc(CH2 )n PH2 , where n=0,1,2,3; and Fc=ferrocenyl, and their corresponding isolable primary phosphine oxides. It was demonstrated that the ferrocene moiety exerts an antioxidant effect on the primary phosphine group, which is intermolecular, solvent dependent and increases with the electron density on the ferrocene moiety. Furthermore, we demonstrated that the presence of ferrocene in solution also inhibits the oxidation of other secondary and tertiary phosphines in air. Together our findings suggest that quenching of singlet oxygen is the actual reason for the antioxidant effect; this was experimentally confirmed by using other established singlet oxygen quenchers, thus demonstrating a key role of singlet oxygen in the aerobic oxidation of phosphines.

Sustainable Photo- and Electrochemical Transformation of White Phosphorous (P4 ) into P1 Organo-Compounds

Elemental white phosphorous (P4 ) is a crucial feedstock for the entire phosphorus-derived chemical industry, serving as a common precursor for the ultimate preparation of high-grade monophosphorus (P1 ) fine chemicals. However, the corresponding manufacturing processes generally suffer from a deep reliance on hazardous reagents, inputs of immense energy, emissions of toxic pollutants, and the generation of substantial waste, which have negative impacts on the environment. In this context, sustainability and safety concerns provide a consistent impetus for the urgent overall improvement of phosphorus cycles. In this Concept, we present an overview of the most recent growth in photo- and electrochemical synthesis of P1 organo-compounds from P4 , with special emphasis on sustainable features. The key aspects of innovations regarding activation mode and mechanism have been comprehensively analyzed. A preliminary look at the possible future direction of development is also provided.

A Stable Primary Phosphane Oxide and Its Heavier Congeners

(Ferrocenylmethyl)phosphane (1) oxidation with hydrogen peroxide, elemental sulfur and grey selenium produced (ferrocenylmethyl)phosphane oxide 1O, sulfide 1S and selenide 1Se, respectively, as the first isolable primary phosphane chalcogenides lacking steric protection. At elevated temperatures, compound 1O disproportionated into 1 and (ferrocenylmethyl)phosphinic acid. In reactions with [(η⁶ -mes)RuCl₂ ]₂ , 1O underwent tautomerization into a phosphane complex [(η⁶ -mes)RuCl₂ {FcCH₂ PH(OH)-κP}], whereas 1S and 1Se lost their P-bound chalcogen atoms, giving rise to the phosphane complex [(η⁶ -mes)RuCl₂ (FcCH₂ PH₂ -κP)] (Fc=ferrocenyl, mes=mesitylene). No tautomerization was observed in the reaction of 1O with B(C₆ F₅ )₃ , which instead produced a Lewis pair FcCH₂ P(O)H₂ -B(C₆ F₅ )₃ . Phosphane oxide 1O added to C=O bonds of aldehydes and ketones and even to cumulenes PhNCE (E=O and S). However, both PH hydrogens were only employed in the reactions with aldehydes and cyanates.

Recent advances in computational 31 P NMR: Part 1. Chemical shifts

This is the first part of two closely related reviews dealing with the computation of phosphorus-31 nuclear magnetic resonance chemical shifts in a wide series of organophosphorus compounds including complexes, clusters, and bioorganic phosphorus compounds. In particular, the analysis of the accuracy factors, such as substitution effects, solvent effects, vibrational corrections, and relativistic effects, is presented. This review is dedicated to the Full Member of the Russian Academy of Sciences Professor Boris A. Trofimov in view of his invaluable contribution to the field of synthesis, nuclear magnetic resonance, and computation studies of organophosphorus compounds.

PO23- and AsO3-: Pnictogenide Ligands in the Highly Charged Re4 Cluster Anions [{Re4(PO)3(PO2)}(CN)12]8-, [{Re4As2(AsO)2}(CN)12]8-, and [{Re4(AsO)4}(CN)12]8

New tetrahedral anionic rhenium cluster complexes [{Re₄(PO)₃(PO₂)}(CN)₁₂]^8- (1) and [{Re₄As₂(AsO)₂}(CN)₁₂]^8- (2) have been synthesized by the reaction of ReI₃ with NaCN and P_red or KCN and As_gray, respectively. Compound 2 was further oxidized by aqueous H₂O₂ to produce the cluster anion [{Re₄(AsO)₄}(CN)₁₂]^8- (3). The anions contain new pnictogen/oxygen-based ligands, PO₂^3- and AsO^3-, which were stabilized by the coordination to the triangular faces of the tetrahedral Re₄ metallocluster in μ₃-mode. All three compounds were crystallized as either sodium or potassium salts, and their crystal structures were determined by single crystal X-ray diffraction analysis.

Hydrogenation reaction pathways in chemistry of white phosphorus

Approaches for preparation of P–H bond containing derivatives directly from white phosphorus are summarized in this microreview. Transfer hydrogenation of P4 involving the activation and reaction of white phosphorus in the coordination sphere of transition metal complexes is a convenient and powerful route to the hydrogenated compounds. Electrochemical methods have also become popular in modern synthetic chemistry; these provide easy access to highly reactive intermediates, which can be selectively generated in situ and used for subsequent synthetic processes. These electrochemical routes provide efficient and environmentally safe methods for preparation of phosphorus derivatives bearing P–H bond. The mechanisms of the proposed processes and the nature of the intermediates formed in the overall electrochemical process are disclosed. The methods elaborated operate under the principals of “green chemistry” and can be considered as efficient alternatives to some classical pathways.

Coordination chemistry and catalysis with secondary phosphine oxides

Review on synthesis, coordination chemistry and catalysis with secondary phosphine oxides.

Electrochemical methods for synthesis of organoelement compounds and functional materials

The new efficient and environmentally safe methods for preparation of various classes of organic and organoelement compounds, including organonickel sigma-complexes and organophosphorus compounds bearing P–C bonds have been created using the electrochemical methods. The synthetic application of the elaborated techniques towards the process of formation of new carbon-carbon, carbon-metal and carbon-phosphorus bonds are discussed. The mechanisms of the proposed processes and the nature of the formed in the overall electrochemical process intermediates are disclosed. The elaborated methods operated in the principals of “green chemistry” can be considered as an efficient alternative to some classical methods for preparation of active catalysts, biologically active molecules and new polynuclear complexes displaying practically useful properties.

Hydroxylated phosphines as ligands for chalcogenide clusters: self assembly, transformations and stabilization

This contribution is a documentation of recent advances in the chemistry of chalcogenide polynuclear transition metal complexes coordinated with mono- and di-phosphines functionalized with hydroxo groups. A survey of complexes containing tris(hydroxymethyl)phosphine (THP) is presented. The influence of the alkyl chain in bidentate phosphines, bearing the P–(CH2)x–OH arms, is also analyzed. Finally, isolation and structure elucidation of the complexes with HP(OH)2, P(OH)3, As(OH)3, PhP(OH)2, stabilized by coordination to Ni(0) and Pd(0) centers embedded into chalcogenide clusters, is discussed.

Disproportionation of hypophosphite and phosphite

³¹P NMR spectra showing that NaH₂PO₂ first disproportionates to NaH₂PO₃, Na₂HPO₃, Na₂H₂P₂O₅ and Na₄P₂O₇, and finally reacts to yield Na₅P₃O₁₀.

Optically active P5-deltacyclenes: selective oxidation, ligand properties, and a diastereoselective rearrangement reaction

Cage-chiral tetra-tert-butyl-P5-deltacyclene is accessible as a pair of highly enriched enantiomers and . The only secondary phosphorus atom P1 of the cage can be selectively oxidized by reaction with t-BuOOH. The P1-oxo species and , allow the direct determination of their ee values. Oxidation occurs with the complete retention of the optical activity of the compounds. The chiroptical properties of and are strongly dominated by their cage chirality, the oxygen atom does not contribute significantly. Elemental sulfur and selenium oxidize P5 with high preference to yield P5-thio- and P5-seleno-P5-deltacyclenes and of the intact cages again. Longer reaction time and more than stoichiometric amounts of selenium, leads to tri-seleno-P5-tetracycloundecane , a partially opened oxidized rearrangement product. The ligand properties of racemic were determined. Diphosphetane phosphorus atom P2 of is the active donor center to bind a Cr(CO)5 fragment, but a tautomerization of takes place if [(benzene)RuCl2]2 is added. A hydrogen atom migrates from P1 to the oxygen atom to form a phosphinous acid ligand. The lone pair of P1 is regenerated and acts as the active ligand function of the cage in this case. As for , the base n-BuLi induces an efficient cage rearrangement reaction of , where P1 and the neighboring carbon atom C4 containing its t-Bu substituent change places. C4 moves to its new position without breaking the bond with P5, this way forming the novel P1-oxo-P5-norsnoutene cage in a highly diastereoselective process.

First principles optimally tuned range-separated density functional theory for prediction of phosphorus–hydrogen spin–spin coupling constants

The novel optimally tuned range-separated approximations for predicting NMR spin–spin coupling constants are proposed and benchmarked numerically.

A straightforward access to ruthenium-coordinated fluorophosphines from phosphorous oxyacids

For the first time, it has been shown the deoxofluorination of metal-coordinated phosphorous oxyacids is feasible using a safe and environmentally friendly “F” source and affords fluorophosphines in a mild and selective way.

Quantum chemical calculations of31P NMR chemical shifts: scopes and limitations

High level of theory is not necessarily needed to obtain rather accurate predictions of³¹P chemical shifts by GIAO method. For example, the PBE1PBE/6-311G(2d,2p)//PBE1PBE/6-31+G(d) combination allowed to obtain good results for variety of middle-size organophosphorus compounds (M= 200–700 Da).

Evaluation of Approximate Exchange-Correlation Functionals in Predicting One-Bond (31)P-(1)H NMR Indirect Spin-Spin Coupling Constants

This work benchmarks density functional theory, with several different exchange-correlation functionals, for prediction of isotropic one-bond phosphorus-hydrogen NMR spin-spin coupling constants (SSCCs). Our test set consists of experimental SSCCs from 30 diverse molecules representing multiple phosphorus bonding environments. The results suggest the importance of a balance between the choice of correlation functional and the admixture of nonlocal exchange. Overall, standard DFT methods appear to suffice for usefully accurate predictions of (31)P-(1)H SSCCs.

Iodine activation of coordinated white phosphorus: formation and transformation of 1,3-dihydride-2-iodidecyclotetraphosphane

Double stabilization: Previously unknown polyphosphorus compounds are obtained by activation of white phosphorus (P(4)) coordinated between two CpRu(PPh(3))(2) moieties with iodine, and subsequent hydrolysis. The polyphosphorus compounds (P(4) H(2) I, P(4) H(2), P(3) H(5); see scheme, Cp=cyclopentadienyl) are all stabilized by coordination to two ruthenium centers.

Morphology control of cadmium selenide nanocrystals: insights into the roles of di-n-octylphosphine oxide (DOPO) and ucid (DOPA)

Di-n-octylphosphine oxide (DOPO) and di-n-octylphosphinic acid (DOPA), as two of impurities found in commercial tri-n-octylphosphine oxide (TOPO), generate significant differences in the outcomes of CdSe-nanocrystal (NC) syntheses. Using n-tetradecylphosphonic acid (TDPA) as the primary acid additive, quantum dots (QDs) are grown with DOPO added, whereas quantum rods (QRs) are grown in the presence of DOPA. While using oleic acid (OA) as the primary acid additive, QDs are generated and the QDs produced with DOPA exhibit larger sizes and size distributions than those produced with DOPO. (31)P NMR analyses of the reaction mixtures reveal that the majority of the DOPO has been converted into DOPA and di-n-octylphosphine (DOP) with DOP being removed via evacuation over the course of Cd-precursor preparation. The origin of the puzzling differences in the shape control of CdSe NCs in the presence of DOPO and DOPA is elucidated to be the small quantity of DOPO present, which liberates DOP during NC synthesis. In the presence of DOP, regardless of DOPA, the precursor-conversion kinetics and thus the nucleation kinetics are dramatically accelerated, generating a large number of nuclei by consuming a significant amount of CdSe nutrients, favoring QD growth. Similarly, QD growth is favored by the fast nucleation kinetics in the presence of OA, and the broader size distributions of QDs with DOPA are due to a second nucleation event initiated by the more stable Cd-di-n-octylphosphinate component. In contrast, a slow nucleation event results in the growth of QRs in the case of using DOPA and TDPA, where no DOPO or DOP is present. The results, thus, demonstrate the important role of precursor-conversion kinetics in the control of NC morphologies.