Use of Lawesson's reagent in organic syntheses.

Recent Advances in Organoselenium Chemistry

Using coordination chemistry to develop new routes to semiconductor and other materials

Stereochemistry of lead(II) complexes containing sulfur and selenium donor atom ligands

Lawesson reagent for selenium fans: Phosphorus selenium heterocycles and, in particular, [PhPSe(2)](2) (known as Woollins' reagent) are proving valuable in the synthesis of new heterocycles and for the insertion of selenium into organic substrates. Incorporation of phosphorus and selenium atoms into the products leads to a surprising variety of structures.Phosphorus-selenium ring chemistry has developed to include the synthesis of some exciting new motifs and provided organic chemists with a new reagent, [PhPSe(2)](2), which has become known as Woollins' reagent.

Formation and Reactivity of Phosphorus–Selenium Rings

A new and improved method for the preparation of (PhPSe 2 ) 2 (Woollins reagent (WR), 1) is reported. Reaction of dichlorophenylphosphine with Na 2 Se, (prepared from the reaction of elemental selenium and sodium in liquid ammonia) gives WR with excellent purity, high yield and on a larger scale than was previously possible. Four novel phosphorus-selenium heterocycles, including a spirocyclic heterocycle exhibiting a four-membered P 2 SeC ring. were obtained from the reaction of WR with two reactive substrates (diphenylcyclopropenone and methyl phenylpropiolate). Useful selenocarbonyl and thiocarbonyl compounds were obtained from the reaction of both WR and Lawesson's reagent with diphenylcyclopropenone. All new compounds were characterised spectroscopically and three demonstrative X-ray structures are reported.

A New Synthesis of (PhPSe2)2 (Woollins Reagent) and Its Use in the Synthesis of Novel P–Se Heterocycles

Reaction of An(S)PS2P(S)An with NaOR [R = Me, Et, iPr] gives the non-symmetric phosphonodithioato anions [An(RO)PS2]− which can be complexed to a range of metals. The group 10 metals (Ni, Pd and Pt) adopt square planar ML2 complexes. The zinc and cadmium complexes adopt isostructural dimeric M2L4 structures whilst mercury complexes adopt a subtly different dimeric motif. Two distinctly different lead complexes are reported, one consisting of PbL2 units joined by Pb⋯S interactions to form distinct dimeric pairs, the other being a completely new structural motif for complexes of this type, PbL2 units held together by covalently bonded bridging ligands to form an infinite polymeric chain structure. All new compounds have been characterised spectroscopically and nine demonstrative X-ray structures are reported.

Synthesis and structure of [An(RO)PS2]− complexes

Reaction of Fc(S)PS2P(S)Fc with NaOR [R = Me, iPr] gives the non symmetric phosphonodithioato anions [Fc(RO)PS2]− which can be complexed to a range of metals The square planar NiL2 complexes adopt two distinct configurations, ‘trans’ with the ferrocenyl groups above and below the square plane and ‘cis’ with the ferrocenyl groups on the same side of the square plane There is good evidence that the isomerisation occurs via a cis-ML2(solv)2 intermediate The zinc and cadmium complexes adopt dimeric M2L4 structures whilst the PbL2 complex has a distorted pyramidal structure and forms infinite chains via Pb⋯S interactions All new compounds have been characterised spectroscopically and seven demonstrative X-ray structures are reported

Synthesis and structure of [Fc(RO)PS2]- complexes

Reaction of (PhPSe2)2
				(Woollins reagent) with NaOR (R = Me, Et, iPr) gives the non-symmetric phosphonodiselenoato anions [Ph(RO)PSe2]− which can be complexed to a range of metals. The nickel complex Ni[Ph(MeO)PSe2]2 adopts a square-planar ML2 structure while the cadmium complex Cd[Ph(MeO)PSe2]2 displays a dimeric M2L4 structure. Two different lead complexes are observed, one consisting of PbL2 units joined by Pb⋯Se interactions to form distinct dimeric pairs. The other displays a novel dimeric structure built around a central four-membered Pb2Se2 ring. All new compounds have been characterised spectroscopically (31P, 1H, 13C NMR, IR, mass spectroscopy), by elemental analysis and five demonstrative X-ray structures are reported.

Synthesis and structure of novel [Ph(RO)PSe2]− complexes

Reaction of Fc(S)PS2P(S)Fc with NaOEt gives the non symmetric phosphonodithioato anion [Fc(EtO)PS2]- which can be complexed to a range of metal ions. The group 10 metals (Ni, Pd and Pt) adopt [ML2] complexes with square planar coordination. The first known mercury phosphonodithioate complex is shown to adopt a unique dimeric [M2L4] structure. A new structural motif for lead phosphonodithioate complexes is reported consisting of [PbL2] units joined by Pb···S interactions to form distinct dimeric pairs. All new compounds have been characterized spectroscopically and four demonstrative X-ray structures are reported.



Synthese und Struktur von [Fc(EtO)PS2]--Komplexen



Die Reaktion von Fc(S)PS2P(S)Fc mit NaOEt fuhrt zu dem nichtsymmetrischen Phosphonodithioato-Anion [Fc(EtO)PS2]-, das mit einer Reihe von Metallionen Komplexe bildet. Mit den Gruppe-10-Metallen (Ni, Pd, Pt) entstehen Komplexe [ML2] mit planar-quadratischer Koordination. Der erste bekannte Quecksilber-Phosphonodithioat-Komplex weist eine dimere Struktur [M2L4] auf. Fur den Blei-Phosphonodithioat-Komplex wird ein neues Strukturmotiv beschrieben, dessen [PbL2]-Einheiten uber Pb···S-Wechselwirkungen Paare bildet. Alle neuen Verbindungen wurden spektroskopisch charakterisiert, von vier der Komplexe wurden die Kristallstrukturen ermittelt.

Ian P. Gray

Papers

A New Synthesis of (PhPSe2)2 (Woollins Reagent) and Its Use in the Synthesis of Novel P–Se Heterocycles

Synthesis and structure of [An(RO)PS2]− complexes

Synthesis and structure of [Fc(RO)PS2]- complexes

Synthesis and structure of novel [Ph(RO)PSe2]− complexes

Synthesis and Structure of [Fc(EtO)PS2]‐ Complexes