Kai‐Oliver Feldmann

Formation of cationic [RP5Cl](+)-cages via insertion of [RPCl](+)-cations into a P-P bond of the P4 tetrahedron.

Fluorobenzene solutions of RPCl(2) and a Lewis acid such as ECl(3) (E = Al, Ga) in a 1:1 ratio are used as reactive sources of chlorophosphenium cations [RPCl](+), which insert into P-P bonds of dissolved P(4). This general protocol represents a powerful strategy for the synthesis of new cationic chloro-substituted organophosphorus [RP(5)Cl](+)-cages as illustrated by the isolation of several monocations (21a-g(+)) in good to excellent yields. For singular reaction two possible reaction mechanisms are proposed on the basis of quantum chemical calculations. The intriguing NMR spectra and structures of the obtained cationic [RP(5)Cl](+)-cages are discussed. Furthermore, the reactions of dichlorophosphanes and the Lewis acid GaCl(3) in various stoichiometries are investigated to obtain a deeper understanding of the species involved in these reactions. The formation of intermediates such as RPCl(2)·GaCl(3) (14) adducts, dichlorophosphanylchlorophosphonium cations [RPCl(2)-RPCl](+) (16(+)) and [RPCl(2)-RPCl-GaCl(3)](+) (17(+)) in reaction mixtures of RPCl(2) and GaCl(3) in fluorobenzene strongly depends on the basicity of the dichlorophosphane RPCl(2) (R = tBu, Cy, iPr, Et, Me, Ph, C(6)F(5)) and the reaction stoichiometry.

Preparation of Ligand‐Stabilized [P4O4]2+ by Controlled Hydrolysis of a Janus Head Type Diphosphorus Trication

A door to new opportunities: The stepwise hydrolysis of a diphosphorus trication is an efficient method for the preparation of an unusual ligand-stabilized dication that contains a novel cationic [P4O4]2+ framework (see Scheme; gray C, blue N, red O, orange P). This approach demonstrates the potential of the diphosphorus trication as a source for phosphorus building blocks to be used in the construction of novel cationic ring and cluster systems.

Multiple‐Charged P1‐Centered Cations: Perspectives in Synthesis

“p-Block elements play key roles in nearly all fields of chemistry.” Modern p-block chemistry has yielded intriguing compounds featuring fascinating properties and unprecedented bonding motifs. 2] Beyond the discovery of novel compounds, it is necessary to develop applications based on the indepth understanding obtained from fundamental research. The increasing demand for economically and ecologically attractive synthetic methods provides additional impetus for the development of novel reagents for unprecedented chemical transformations. Phosphorus-centered cations were long considered laboratory curiosities. However, a plethora of P-centered cations which show a large variety of bonding motifs involving the phosphorus atom became recently available. Prominent phosphorus-based transformations such as the Wittig, Mitsunobu, Corey–Fuchs, and Michaelis–Arbuzov reactions proceed via monocationic intermediates. Despite their often intriguing properties, the potential of phosphorus cations as powerful reagents in synthesis has largely remained neglected. It therefore seems that an investigation of multiplecharged P1-centered cations as reagents in synthesis is long overdue. Among the multitude of bonding motifs described for multiple-charged P1-centered cations, [5] [L2PCl] 2+ and [L3P] 3+

A versatile protocol for the quantitative and smooth conversion of phosphane oxides into synthetically useful pyrazolylphosphonium salts.

A convenient protocol for the smooth conversion of the resistant P-O bond in phosphane oxides into a reactive P-N bond of synthetically useful pyrazolylphosphonium salts is described. A highly charged, oxophilic, phosphorus-centered trication is employed and the reactions are conducted at room temperature with quantitative yields. The resulting pyrazolylphosphonium cations are valuable synthetic intermediates and are used for the synthesis of a variety of organophosphorus compounds. This represents a new approach towards the transformation of the rather inert phosphoryl group under very mild reaction and workup conditions and aims towards alternatives to existing reduction methods for phosphane oxide functionalization.

P3Se4 (+): A Binary Phosphorus-Selenium Cation

Although a fairly large number of binary group 15/16 element cations have been reported, no example involving phosphorus in combination with a group 16 element has been synthesized and characterized to date. In this contribution is reported the synthesis and structural characterization of the first example of such a cation, namely a nortricyclane-type [P3Se4](+). This cation has been independently discovered by three groups through three different synthetic routes, as described herein. The molecular and electronic structure of the [P3Se4](+) cage and its crystal properties in the solid state have been characterized comprehensively by using X-ray diffraction, Raman, and nuclear magnetic resonance spectroscopies, as well as quantum chemical calculations.