Phosphorus chemistry: discoveries and advances

“Ohne Phosphor, Kein Gedanke”¹

If Moleschott's words are true, then this issue, “Phosphorus Chemistry: Discoveries and Advances”, may well be Dalton Transactions' most deep and varied in thought. Dear reader, we present more than 50 new contributions to the diverse field of phosphorus chemistry. This special issue bears out two truths in phosphorus chemistry: it is a microcosm of all science, and interest in this element is perpetual. Phosphorus indeed touches all fields, and within the scope of the journal, aspects of biology, medicine, synthesis, catalysis, materials, and energy are considered in this issue.

Increased research organization in the field is evident from two recent COST Action programs, PhosSciNet and Smart Inorganic Polymers. The chair of both Actions, Evamarie Hey-Hawkins has two contributions (DOI: 10.1039/C5DT02564H and 10.1039/C5DT03374H), and the co-chairs of the respective Actions, Koop Lammertsma (DOI: 10.1039/C5DT03994K) and Muriel Hissler (DOI: 10.1039/C5DT04154F), have each contributed as well. I am also pleased to note that many of the participants in these Actions have contributions in this special edition.

The importance of phosphorus as a finite resource has been highlighted by the International Conference on Sustainable Phosphorus Chemistry (SUSPHOS) series, initiated in 2015. That conference arose from the European Training Network for Sustainable Phosphorus Chemistry, led by Chris Slootweg, who has a contribution in this issue (DOI: 10.1039/C5DT03994K). It is exciting that many key contributors to that innovative training effort have articles in this special edition.

Activity in the area of phosphorus chemistry never wanes. The articles for this issue were assembled in 2015, the year between the 20^th International Conference on Phosphorus Chemistry in Dublin and the impending 21^st ICPC in Kazan. It is a great pleasure to have so many of the invited, keynote, and plenary lecturers from that series of international events participate in this special issue. Of course, achievements in the field of phosphorus chemistry feature prominently in sub-disciplinary venues throughout the largest multinational events. Indeed, I am delighted that two of my co-organizers for the “Advances in Phosphorus Chemistry” symposium at the International Congress of Pacific Basin Societies (Pacifichem), Pak-Hing Leung (DOI: 10.1039/C5DT02049B) and Fumiyuki Ozawa (DOI: 10.1039/C5DT03166D), each have contributions in this edition.

Terrific insight into the field comes from the rich list of Frontier and Perspective contributions. There are Frontier articles on phosphazene polymers from Allcock (DOI: 10.1039/C5DT03887A), dehydrocoupling of P(V) substrates by Han (DOI: 10.1039/C5DT01896J), and stimulus-response behavior in the chromism of organophosphines by Baumgartner (DOI: 10.1039/C5DT02758F). The Perspective articles have an equally diverse range, from E–H bond activation at phosphinidene derivatives by Mathey (DOI: 10.1039/C5DT02532J) to Caminade's contribution on the use of phosphazenes in the synthesis of dendrimers (DOI: 10.1039/C5DT03047A) to the resolution of P-chiral phosphacycles by Keglevich (DOI: 10.1039/C5DT02999F), which reminds us of the late William Knowles's lesson that phosphorus stereochemistry is “where the action is”.

Phosphorus remains a key element in materials chemistry. Long standing interest in important phosphazene systems continues here with a contribution from Allen (DOI: 10.1039/C5DT02762D) on phosphazene–phosphazane rearrangements. One example in the spectrum of applications that polyphosphazenes have realized comes from Carriedo (DOI: 10.1039/C5DT02670A) in a report on their application in Stille couplings.

Phosphine–boranes are, in comparison to phosphazenes, a more emergent material precursor, and a contribution on the dehydrocoupling of this substrate by Kilian (DOI: 10.1039/C5DT02539G) is included. Exploration of electronic, physical, and optical properties of phosphorus materials comes from contributions by Musina (DOI: 10.1039/C5DT03346B) involving luminescent copper compounds supported by phospholane-containing ligands and Matano (DOI: 10.1039/C5DT03362D) on the electronic and optical properties of substituted phospholes. Furthermore, Monge (DOI: 10.1039/C5DT03289J) communicates on the preparation of block copolymers that exhibit thermal sensitivity.

Inorganic rings, particularly those containing phosphorus, are a steadfast area of interest as evidenced by the continued success of the International Symposium on Inorganic Ring Systems meetings. The most recent event in the series, IRIS-14, was hosted by Manfred Scheer, who has a contribution in this issue (DOI: 10.1039/C5DT01750E). Nyulászi and Pietschnig (DOI: 10.1039/C5DT03107A) demonstrate the continued interest in these rings with a study on bridged [3]ferrocenophosphine rings, while Grützmacher (DOI: 10.1039/C5DT03014E) outlines the preparation of cyclophosphines from a parent carbene–phosphinidene, Wright (DOI: 10.1039/C5DT04393J) communicates the preparation of a para-di(phosphazane)benzene, and Chandrasekhar (DOI: 10.1039/C5DT03537F) reports on 1- and 2-D assemblies from phosphazene-based precursors.

The inorganic and synthetic chemistry of phosphorus remains tremendously rich, with new efforts from phosphinium ions to low-valent species continuing to emerge. Burford (DOI: 10.1039/C5DT03116H) reports on unique triphosphorus diphosphonium ions. Streubel (DOI: 10.1039/C5DT03404C) reports on the deoxygenation and rearrangements of oxaphosphirane derivatives. Müller (DOI: 10.1039/C5DT03609G) investigates the reactivity and coordination of phosphinine systems. Pikies (DOI: 10.1039/C5DT03085D) shares developments on the reactivity of a phosphinophosphinidene complex of tungsten. New understanding of P–P bonding comes from Gudat (DOI: 10.1039/C5DT02854J) in a study of the dissociation of diphosphanes.

Interest in the construction of inorganic and organometallic compounds around P_n building blocks remains intense, as evidenced by contributions from Schulz (DOI: 10.1039/C5DT02757H, a HOT article!), using P_n in the synthesis of tetraphosphanes, Goicoechea (DOI: 10.1039/C5DT02380G), applying P₇ in the preparation of anionic clusters with a group 14 element, and Weigand (DOI: 10.1039/C5DT01512J), in which P_n units are key parts in spirocyclic cage compounds.

Frustrated Lewis pair (FLP) chemistry has become an explosive topic—the subject of a recent themed collection in Dalton—and phosphines are often key components in these systems. Kehr and Erker (DOI: 10.1039/C5DT03055B) report on a synthesis of phospholes obtained via FLP-mediated carboration, and Uhl (DOI: 10.1039/C5DT02825F) describes a masked aluminum–phosphorus FLP in the form of a new Al,P-heterocycle.

The preparation of even seemingly simple phosphorus derivatives remains a challenge and is fertile ground for new discoveries. Crossley (DOI: 10.1039/C5DT03558A) reports on the formation of a phosphinoallene during the study of preparative routes to propargyl phosphanes. The oxidative dephosphonylation of aminophosphonic acids is reported by Drabowicz (DOI: 10.1039/C5DT03083H), and Macdonald (DOI: 10.1039/C5DT03019F) shares a new preparative route to phosphamethine cyanines from simple precursors.

Organophosphines have been pivotal ligands in transition-metal chemistry. A report from Thomas (DOI: 10.1039/C5DT03549J) describes new nickel derivatives supported by phosphenium pincer ligands, and Auffrant (DOI: 10.1039/C5DT02789F, a HOT article!) reports on a phosphine–iminophosphorane pincer complex of palladium. Boeré (DOI: 10.1039/C5DT03393D) investigates phosphaalkene chemistry through the coordination of phosphaamidines to metals. Heinicke (DOI: 10.1039/C5DT04073F) reports a family of d⁸ metal compounds supported by new 3H-1,3-azaphospholo-pyridine ligands. López Ortiz (DOI: 10.1039/C5DT02860D) demonstrates a concise preparation of P-stereogenic phosphinic amides, which have been coordinated to zinc. Caporali and Peruzzini (DOI: 10.1039/C5DT04624F) report the deoxofluorination of phosphorous oxyacids coordinated to ruthenium. Latypov and co-workers (DOI: 10.1039/C5DT02604K) continue work on their nickel system by investigating its intramolecular reactivity.

The legacy of phosphorus supporting metal catalysis continues here in the form of rhodium hydrogenation catalysis from Fontaine (DOI: 10.1039/C5DT03109E), palladium-catalyzed Suzuki reactions from Biffis (DOI: 10.1039/C5DT02250A), chromium-catalyzed ethylene oligomerization by Pringle (DOI: 10.1039/C5DT04394H), and a communication on hydroarylation catalysts by Alcarazo (DOI: 10.1039/C5DT02341F). However, the catalytic activity of phosphorus itself cannot be discounted. Higham (DOI: 10.1039/C5DT04475H) communicates on hydrosilylation catalysis with new phosphonites. Ott (DOI: 10.1039/C5DT03686K) reports a unique phosphanylphosphonate and its reactivity in phospha–Wittig–Horner chemistry. At the same time, the synthesis of phosphorus-containing compounds profits greatly from catalysis. Herein, Han (DOI: 10.1039/C5DT02454D) communicates new iron-catalyzed P–H and C–O bond coupling reactions. Kamer (DOI: 10.1039/C5DT03226A) describes the synthesis of a library of new phosphine–phosphite ligands to support catalysts using a modular, solid-phase approach.

Similarly, phosphines have been key ligands in polymetallic compounds and metal clusters. Mastrorilli (DOI: 10.1039/C5DT02593A) reports on reductive coupling reactions in platinum clusters, Cummins (DOI: 10.1039/C5DT03383G) describes Sn–P and Pb–P rings as bridging ligands in diniobium compounds, and Ruiz (DOI: 10.1039/C5DT01450F) demonstrates P–S bond cleavage in the formation of heterometallic, phosphinidene-bridged compounds.

Finally, it would be remiss of me not to thank the Editorial Board of Dalton for selecting this topic and allowing me the opportunity to guest edit. The mechanics of the issue are the result of the diligent efforts of the editorial team at Dalton, to which I owe great thanks, but I would like highlight Dr Guy Jones for his key role in the initial development of the issue.

It is with great pleasure that I present to you this special issue of Dalton Transactions. I invite you to enjoy it and revel in the thought that so much phosphorus provokes.

References

1. J. Moleschott, Lehre der Nahrungsmittel, Verlag Von Ferdinand Enke, Erlangen, 1850, p. 116.

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