The Coordination Chemistry of the CF Unit in Fluorocarbons.

In recent years, research in organophosphorus chemistry has mainly focused in designing newer and better phosphorus ligands for synthesizing novel metal complexes with improved catalytic activities. Aminophosphines [tricoordinate phosphorus(III)–nitrogen systems] are considered as versatile compounds owing to the presence of nitrogen centres which, in principle, can influence additional reactivity features. They are quite sensitive to air and moisture due to the presence of polar PN bond(s). In spite of this, research in aminophosphine chemistry is gaining momentum day-by-day and this is due mainly to one reason: their rich behaviour as ligands in metal complex chemistry and subsequently in catalysis. Their role as synthons in inorganic heterocyclic chemistry has also helped produce new types of heterocycles. In this paper, the chemistry of simple acyclic aminophosphines (synthesis, characterization, reactivity and applications) is covered and particular focus is given to their ability to form chalcogenides along with their role played as ligands in coordination chemistry and as synthons in inorganic heterocyclic chemistry. Copyright © 2009 John Wiley & Sons, Ltd.

Aminophosphines: their chemistry and role as ligands and synthons

Fluorinated alcohols and their metal complexes

Arsenic is a potentially essential element for mammals and is abundant in certain marine organisms. Arsenic compounds have been widely used as drugs in the past and were used until recently as growth promoters for some farm animals. Here we review the structures, reactivities and biological and pharmacological activities of arsenic compounds, emphasising both the similarities to and differences from other Group V elements (P, Sb, Bi). There appear to be no crystal structures of As-containing peptides or proteins, and the inhibition of thiol-enzymes by As(III), although widely quoted, is poorly understood. There is much scope for the design of arsenic compounds as drugs, but progress depends on the discovery of new probes for investigating the structural and redox chemistry and biochemistry of arsenic, especially in aqueous media.

The structure and reactivity of arsenic compounds: Biological activity and drug design

Cyclic and Heterocyclic Thiazenes

NaSCN und KOCN reagieren mit Hexafluoraceton (HFA) im Molverhaltnis 1:2 unter Abbau des Anions in einem Schritt zu den Hexafluorpropanimin-Derivaten (CF3)2CNC(CF3)2OM (2a, b) (MNa, K), wahrscheinlich uber (CF3)2CN– als Zwischenstufe. Die Hydrolyse von 2a in Gegenwart wasriger Tetraphenylphosphoniumchlorid-Losung ergibt ein kristallines Hydrat der Zusammensetzung[(CF3)2C(OH)2·(CF3)2C(O)OH]– Ph4P+ (3). Im Kristall liegen dimere Dianionen vor, die uber vier asymmetrische und zwei symmetrische Wasserstoff-Bruckenbindungen verknupft sind. In einer unubersichtlichen Reaktion entsteht bei einem Reaktandenverhaltnis KSCN/HFA von 1:1 die polycylische Bisspiroverbindung 5. Kaliumselenocyanat reagiert mit HFA unter C – Se-Bindungsspaltung und nachfolgender Bildung des CF3-substituierten Oxazolidins 6. Die Rontgenstrukturanalysen von 2a, 3, 5 und 6 werden mitgeteilt.



Reactions of Hexafluoroacetone with Alkali Cyanates



NaSCN and KOCN react with hexafluoroacetone (HFA) in a molar ratio of 1:2 in a one-step reaction to yield the hexafluoropropanimine derivatives (CF3)2CNC(CF3)2OM (2a, b) (MNa, K). (CF3)2CN– is a possible intermediate. Hydrolysis of 2a in aqueous tetraphenylphosphonium chloride solution yields a crystalline hydrate of composition [(CF3)2C(OH)2·(CF3)2C(O)OH]– Ph4P+ (3). In the solid state dimeric dianions are observed, which are connected via four asymmetrical and two symmetrical O H O bonds. Starting with a 1:1 KSCN/HFA stoichiometry the polycyclic bisspiro compound 5 is formed in a complex reaction. In the reaction of potassium selenocyanate with HFA the C–Se bond is cleaved and the CF3-substituted oxazolidine 6 is formed. The X-ray structure analyses of 2a, 3, 5 and 6 are reported.

Reaktionen von Hexafluoraceton mit Alkalicyanaten

Aus den (Disilylamino)phosphanen (Rf)2P – N(SiMe3)2 (Rf CF3, C2F5) und S3N2Cl2 werden unter Abspaltung von Me3SiCl und S8 neue Cyclophosphadithiatriazene der Zusammensetzung (Rf)2PN3S2 (1a, b) erhalten. Als Nebenprodukte treten Phosphanimide (Rf)2P(Cl) NSiMe3 (2a, b) auf. 1a, b bilden mit Norbornadien 1:1-Addukte 3a, b. Die Rontgenstrukturanalyse von 3a (Rf CF3) wird mitgeteilt. Aus 1a bildet sich nach mehrtagigem Stehenlassen eine kristalline Verbindung [(CF3)2PN2S]2 (4), deren Rontgenstrukturbestimmung einen achtgliedrigen Ring mit 1,3-P(CF3)2-Gruppen zeigt.



(Disilylamino)phosphanes (Rf)2P – N(SiMe3)2 – Precursors for PN3S2 Rings



The reactions of the (disilylamino)phosphanes (Rf)2P – N(SiMe3)2 (Rf CF3, C2F5) with S3N2Cl2 lead to new cyclophosphadithiatriazenes of composition (Rf)2PN3S2 (1a, b) with elimination of Me3SiCl and S8. By-products are (Rf)2P(Cl) NSiMe3 (2a, b). Reaction of 1a, b with norbornadiene yields 1:1 adducts 3a, b. The X-ray structure analysis of 3a (Rf CF3) is reported. When 1a is allowed to stand for several days a crystalline compound of composition [(CF3)2PN2S]2 (4) is formed. The X-ray structure analysis shows that 4 contains an eight-membered ring with 1,3-P(CF3)2 groups.

(Disilylamino)phosphane (Rf)2P – N(SiMe3)2 – Bausteine für PN3S2‐Ringe

Hexafluoraceton (HFA) reagiert mit Nitrilen der V. Hauptgruppe, wie CF3P(CN)2 (1), P(CN)3 (2) und Sb(CN)3 (3), unter Spaltung der E CN-Bindungen zu den Verbindungen 4 – 6. Triethylamin katalysiert die unter milden Bedingungen ablaufenden Reaktionen. Ein vollstandig anderer Reaktionstyp wird im Fall des Se(CN)2 beobachtet; hier wird ein Molekul Triethylamin in die entstehende Verbindung 7 eingebaut. As(NCS)3 addiert je zwei Molekule HFA uber die C N-Dreifachbindung zum symmetrischen Trithioarsenit (8). Von 4, 7 und 8 werden die Kristallstrukturen mitgeteilt.



Reactions of Hexafluoroacetone with Nitriles of Main Groups V and VI



Hexafluoroacetone (HFA) reacts with nitriles of group V elements like CF3P(CN)2 (1), P(CN)3 (2), and Sb(CN)3 (3) via E CN bond cleavage to yield compounds 4 – 6. The reactions are catalyzed by triethylamine and proceed under mild conditions. A completely different reactivity is observed for Se(CN)2, where triethylamine is incorporated into the resulting compound 7. As(NCS)3 adds two molecules of HFA per ligand across the C N triple bond forming the symmetric trithioarsenite (8). The crystal structures of 4, 7, and 8 are reported.

Reaktionen von Hexafluoraceton mit Nitrilen der V. und VI. Hauptgruppe

Das vollstandige Manuskript dieser Zuschrift erscheint in: Angew. Chem. Suppl. 1983, 1424. DOI: 10.1002/ange.198314240

Synthese und Struktur eines Makrocyclus mit einem Gerüst aus Arsen‐, Kohlenstoff‐, Sauerstoff‐ und Stickstoffatomen

Two new aminoarsines, (CF3)2AsN(SiMe3)2(1) and CF3As[N(SiMe3)2]2(2), are formed by reaction of (CF3)2AsCl and (CF3)AsCl2 with LiN(SiMe3)2. Chlorination of (1) yields [(CF3)2As(Cl)N(SiMe3)]2(3). On refluxing (3) in n-hexane or n-heptane, the synthesis of trimeric and tetrameric bis(trifluoromethyl)arsazenes, [(CF3)2AsN]3(4) and [(CF3)2AsN]4(5), is accomplished. Pyrolysis of (3) also produced (4) and (5). Crystals of (5) are triclinic, space group P, with a= 991.2(5), b= 1 012.9(6), c= 1 432.8(7) pm, α= 108.21(4), β= 96.03(4), γ= 109.44(4)°, and Z= 2. The structure was solved by direct methods and refined to R 0.069 for 2 183 unique observed diffractometer data. The molecular symmetry approximates to (S4), with a slight alternation in As–N distances [171.6(7) and 173.2(9) pm].

Joachim Lucas

Papers

Reaktionen von Hexafluoraceton mit Alkalicyanaten

(Disilylamino)phosphane (Rf)2P – N(SiMe3)2 – Bausteine für PN3S2‐Ringe

Reaktionen von Hexafluoraceton mit Nitrilen der V. und VI. Hauptgruppe

Synthese und Struktur eines Makrocyclus mit einem Gerüst aus Arsen‐, Kohlenstoff‐, Sauerstoff‐ und Stickstoffatomen

Preparation of trimeric and tetrameric bis(trifluoromethyl)arsazene; X-ray study of [(CF3)2AsN]4