Reactivity of Sodium Pentaphospholide Na[cyclo-P5] towards C≡E (E=C,N, P) Triple Bonds

A diglyme solution of Na[cyclo-P₅] ( 1 ) reacts with alkynes and isolobal nitriles and phosphaalkynes to afford the otherwise elusive (aza)phospholide anions 2 a – c , 4 a,b , and 6 . The reaction of Na[cyclo-P₅] with alkynes and nitriles was studied by means of DFT methods, which suggested a concerted mechanism for the formation of 2 a and 4 b . The anions 2 a – c , 4 a,b , and 6 coordinate in an η⁵-fashion towards Fe^II to give the sandwich (aza)phosphametallocenes 3 a – c , 5 a,b and 7 in moderate to good yields. The new compounds were characterized by means of multinuclear NMR spectroscopy, single-crystal X-ray diffraction and cyclic voltammetry.     

Ein ungewöhnlicher trimerer Bimetallkomplex mit dem Gerüst [Zr3(μ2-OH)3(μ3-O)Li5] durch Reaktion von Zirconiumorgano- und -hydrido-Komplexen mit Wasser

An Unusual Trimeric Bimetallic Li? Zr Complex with the Backbone [Zr₃(μ₂-OH)₃(μ₃-O)Li₅] by Reaction of Zirconiumorgano and Hydrido Complexes with Water The reaction of compounds of the type [(LZr)(LiH)(L′)]_n and [(LZr)(LiH)(L′)(alkyne)]_n (L: 2,2′-Biphenolato-dianion, L′: thf, Bu₃P, alkyne: Ph? C?C? SiMe₃, CH?CH) with water at 0°C in a thf solution results in the formation of th trimeric bimetallic complex 8 [(L₂Zr)₃(μ₂-OH)₃(μ₃-O)Li₅(thf)₈(H₂O)₅] in 50% yield. The X-ray analysis of 8 shows that a planar six-membered ring Zr₃(μ₂-OH)₃ is formed. In the middle of this ring is a dianionic oxygen atom placed, coordinating to the three L₂Zr centres in a planar μ₃-coordination (bond angles 120,05μ). Five lithium ions stabilize the anionic backbone by bridging the biphenolato chelate ligands, which form seven-membered chelate rings with the atoms. ¹H-, ¹³C-, and ⁷Li-NMR spectra exhibit that the solid state structure remains unchanged in solution (thf).     

Zur Reaktivität von Titanocenkomplexen [Ti(Cp′)2(η2‐Me3SiC≡CSiMe3)] (Cp′ = Cp,Cp*) gegenüber Benzoldicarbonsäuren

On the Reactivity of Titanocene Complexes [Ti(Cp′)₂(η²‐Me₃SiC≡CSiMe₃)] (Cp′ = Cp, Cp*) towards Benzenedicarboxylic Acids Titanocene complexes [Ti(Cp′)₂(BTMSA)] ( 1a , Cp′ = Cp = η⁵‐C₅H₅; 1b , Cp′ = Cp* = η⁵‐C₅Me₅; BTMSA = Me₃SiC≡CSiMe₃) were found to react with iodine and methyl iodide yielding [Ti(Cp′)₂(μ‐I)₂] ( 2a / b ; a refers to Cp′ = Cp and b to Cp′ = Cp*), [Ti(Cp′)₂I₂] ( 3a / b ) and [Ti(Cp′)₂(Me)I] ( 4a / b ), respectively. In contrast to 2a , complex 2b proved to be highly moisture sensitive yielding with cleavage of HCp* [{Ti(Cp*)I}₂(μ‐O)] ( 7 ). The corresponding reactions of 1a / b with p‐cresol and thiophenol resulted in the formation of [Ti(Cp′)₂{O(p‐Tol)}₂] ( 5a / b ) and [Ti(Cp′)₂(SPh)₂] ( 6a / b ), respectively. Reactions of 1a and 1b with 1,n‐benzenedicarboxylic acids (n = 2–4) resulted in the formation of dinuclear titanium(III) complexes of the type [{Ti(Cp′)₂}₂{μ‐1,n‐(O₂C)₂C₆H₄}] (n = 2, 8a / b ; n = 3, 9a / b ; n = 4, 10a / b ). All complexes were fully characterized analytically and spectroscopically. Furthermore, complexes 7 , 8b , 9a ·THF, 10a / b were also be characterized by single‐crystal X‐ray diffraction analyses.     

Electron Transfer in a Supramolecular Associate of a Fullerene Fragment

Herein, we investigate the association of a fullerene fragment, hemifullerene C₃₀H₁₂, with an electron‐donating bowl‐shaped tetrathiafulvalene derivative (truxTTF). UV/Vis titrations and DFT calculations support formation of the supramolecular complex, for which an association constant of log K_a=3.6±0.3 in CHCl₃ at room temperature is calculated. Remarkably, electron transfer from truxTTF to C₃₀H₁₂ to form the fully charge‐separated species takes place upon irradiation of the associate with light, constituting the first example in which a fullerene fragment mimics the electron‐accepting behavior of fullerenes within a supramolecular complex.     

Asymmetric polymerase chain reaction improves streptavidin–biotin based purification of polymerase chain reaction products prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis

Asymmetric polymerase chain reaction (PCR) simplifies the application of biotin–streptavidin based purification formats for PCR products in matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis. The use of an excess of non-biotinylated primer improves the turnover of biotinylated primer. Thereby performance deficiencies caused by non-extended biotinylated primer are eliminated. © 1998 John Wiley & Sons, Ltd.     

Magnesium Complexes Bearing η2-Pyrazolato Ligands

Despite the small size of the magnesium ion , η²-bound pyrazolato ligands are found in complexes 1 – 3 . These complexes provide new insight into the design of volatile Group 2 metal complexes for use in chemical vapor deposition processes.     

Chemie und Aufbau der Wolle

Wool is a fibrous biomaterial with an exceptional multicellular structure and complex chemical composition. This is shown for some selected topics.     

The total ponderomotive force and inhomogeneity indicators

Droplets on outdoor high‐voltage equipment suffer a total ponderomotive force which is non‐vanishing in general. We show that this force can be given as a series of inhomogeneity indicators of the undisturbed electric field in the absence of the droplet. We use 2d and 3d Fourier techniques to prove the series expansion as a relation between the solutions of two Poisson's equations on different domains. The order of magnitude of the terms in the series expansion is discussed. It is found that the expansion converges fast in applicatory cases. The results are applied for droplets on a realistically shaped insulator. Copyright © 2006 John Wiley & Sons, Ltd.