Pradip K. Bakshi

Das reaktionsverhalten von Cp2MoCl2 gegenüber WF6 und NOBF4 — struktur von [Cp2MoCl2][BF4]

Abstract The oxidation of CpMoCl 2 ( 1 ) with WF 6 or NOBF 4 to yield cationic molybdenum(V) species was estimated on the basis of a simple Born-

Das Reaktionsverhalten von Cp2NbCl2 gegenüber WF6—Struktur von [Cp2NbCl2]4+[WF6]2−[WCl6]2−

The oxidation of Cp2NbCl2 with pure WF6 in SO2 solution yielded the cationic metallocene species [Cp2NbCl2]+[WF6]− essentially in quantitative yield. The same reaction carried out in the presence of either equimolar amounts or a two-fold excess of HCN led to the preparation of the new niobocenium salt [Cp2NbCl2]4+[WF6]2− which was studied by single crystal X-ray diffraction. This compound represents the first example of a structurally characterized metallocene-WF6− complex, and crystallizes in the tetragonal system: space group, P41212(No. 92), a = 11.083(8) A, c = 48.285 (9) A; Z = 8; R = 0.0759, RW = 0.0841. ab]Die Oxidation von Cp2NbCl2 mit reinem WF6 fuhrt in SO2-Losung zur Synthese von [Cp2NbCl2 ]+[WF6]− in nahezu quantitativer Ausbeute. Die analoge Reaktion fuhrt unter Anwesenheit der aquimolaren Menge oder eines zweifachen Uberschusses an HCN zur Ausbildung des Niobocenium-Komplexsalzes [Cp2NbCl2]4+ [WF6]2−[WCl6]2−, von dem eine Rontgenstrukturanalyse angefertigt wurde. Diese Verbindung reprasentiert den ersten structurell charakterisierten Vertreter eines Metallocen-WF6−-Komplexes und kristallisiert im tetragonalen System: Raumgruppe P41212 (Nr. 92), a = 11.083(8) A, c = 48.285(9) A; Z = 8; R = 0.0759, RW = 0.0841. kw]Niobium; X-ray diffraction; Oxidation; Metallocenes

The stability of Carbenic and Alkenic Phosphorus Environments

Abstract The factors responsible for the isolation or identification of (carbenic) phosphenium and (alkenic) tricoordinate phosphonium salts are discussed. Structural features, reactivity and observations of intramolecular rearrangement are presented, which illustrate some of the requirements for stability in each case.

Evidence for anionic protection of phosphenium centres

The new phosphenium salt [P(NPri2)2][BPh4] has been identified in solution and observed to react with chlorinated solvents, including a facile oxidative addition of CH2Cl2 to the cation; in contrast, similar solutions of the [GaCl4]– salt are indefinitely stable indicating that the gallate anion suppresses the reactivity of the cation.

Coordination of neutral ligands to a neutral phosphorus system

Structural characterization of complexes involving neutral ligands (quinuclidine and tetramethylethylenediamine) coordinated to a neutral phosphorus system shows unusually long (> 2.00 A) N → P coordinative bonds; the bidentate ligand links two phosphorus acceptors.

Reactions of trans-2-alkoxy-1-cycloalkyltellurium(IV) trihalides with N-substituted anilines : the X-ray crystal structure of p-N-ethylanilino(trans-2-ethoxy-1-cyclohexyl)tellurium(IV) dibromide

Abstract trans-2-Alkoxy-1-cycloalkyltellurium(IV) trihalides react with N-substituted anilines to give p-N-substituted anilino (trans-2-alkoxy-1-cycloalkyl)tellurium(IV) dihalides. The crystal structure of p-N-ethylanilino(trans-2-ethoxy-1- cyclohexyl)tellurium(IV) dibromide has been determined by X-ray crystallography. Tellurium is four coordinated with pseudo trigonal bipyramidal geometry and an equatorial lone pair of electrons. Single crystals of p- EtHNC6H4(EtOC6H10)TeBr2 are monoclinic with space group P21/c (No. 14), a=9.304(5), b=8.179(2), c=24.932(5) A, β=92.34(4)°, V=1896(1) A3, Dcalc=1.8738 g cm−3 for Z=4. The structure was refined to R=0.0538 (Rw=0.0633).

Reaction of Mes NPC1 with Triphenylcarbenium Tetrafluoroborate

Abstract Reaction of Mes NPC1 with triphenylcarbenium salts (BF4 or PF6) produces a difluorophosphine and not the expected iminophosphenium cation. This compound then undergoes an Arbusov-type rearrangement to generate a difluoro-iminophosphorane.