[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.

P-N/P-P bond metathesis for the synthesis of complex polyphosphanes.

A unique hexaphosphane featuring a 2,2'-bi(1,2,3-triphosphacyclopentane) moiety (19) and an ethylene-bridged bis-isotetraphosphane (27(c,m)) were both selectively prepared in efficient one-pot syntheses from easily accessible tris(3,5-dimethyl-1-pyrazolyl)phosphane (14) and 1,2-bis(phenylphosphanyl)ethane (18(c,m)). The formation of 27(c,m) is an example of a highly efficient P-P bond formation via protolysis. In contrast, the formation of 19 comprises P-N/P-P bond metathesis steps.

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.

Access to catenated and branched polyphosphorus ligands and coordination complexes via a tri(pyrazolyl)phosphane.

We report a convenient and smooth protocol for the high-yielding synthesis of a triphosphane and an iso-tetraphosphane from a readily accessible tri(pyrazolyl)phosphane. The products are obtained from a one-pot reaction at room temperature and form complexes with the Fe(CO)(4)-fragment.

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.

Carbene-stabilized phosphorus(III)-centered cations [LPX(2)](+) and [L(2)PX](2+) (L = NHC; X = Cl, CN, N(3)).

A versatile, high-yielding synthesis of NHC-stabilized [PCl(2)](+) and [PCl](2+) phosphorus synthons has been achieved by using an "onio-substituent transfer" reagent. Subsequent functionalization yields access to cationic cyano- and azido-substituted derivatives which represent first examples of a displacement reaction on NHC-stabilized phosphorus(III)-centered cations. The new salts have been fully characterized by NMR spectroscopy and X-ray crystallography.

Synthesis of NHC complexes by template controlled cyclization of beta-functionalized isocyanides.

Starting from complexes of type [Ru(Cp)Cl(P-P)] (P-P = 2PPh3, 3a; P-P = 2PMe3, 3b: P-P = dppe, 3c; P-P = dppp, 3d) isocyanide complexes [Ru(Cp)(P-P)(CNR) 4a-4d (CNR = CN-CH2-CH2N3, 1) and 7a-7d (CN-C6H4-2N3, 2) have been prepared. Reduction of the azido functions of the coordinated isocyanide ligands with Zn/NH4Cl/H2O in methanol leads to coordinated 2-amino functionalized isocyanides which cyclize to yield the complexes with a saturated NH,NH-stabilized NHC ligand 5a-5d or a benzannulated NH,NH-stabilized NHC ligand 8a-8d. The Zn/NH4Cl/H2O reduction method is of general applicability and allowed the generation of complex 11 bearing three saturated NH,NH-stabilized NHC ligands.

Palladium-catalyzed domino C-C/C-N coupling using a norbornene template: synthesis of substituted benzomorpholines, phenoxazines, and dihydrodibenzoxazepines.

A rapid, four-step approach to alkyl- and aryl-substituted benzomorpholines is accomplished by a Pd-catalyzed domino C-C/C-N bond coupling using a norbornene template. Extension to phenoxazines and dihydrodibenzoxazepines is presented.

Template-controlled synthesis of a planar [16]ane-P2C(NHC)2 macrocycle.

Reaction of tetraphosphine platinum(II) complexes with 2-azidoethyl isocyanide 3 in methanol leads to complexes with two trans-coordinated NH,NH-stabilized carbene ligands 6(X)(2). Complexes 6(X)(2) react with phenyldivinylphosphine under substitution of the remaining phosphine ligands followed by an intramolecular hydroamination reaction to produce complex 1(PF(6))(2) with a macrocyclic [16]ane-P(2)C(NHC)(2) ligand.