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Co-pyrolysis reactions of B2Br4 with S2Br2 at 350 °C in vacuo yielded the brominated thiaboranes closo-SB5Br5 (1), closo-1-SB9Br9 (2) and closo-SB11Br11 (3), confirmed by high-resolution mass spectrometry, experimental and computational 11B NMR spectroscopy. The strong Brδ+(σ-hole)⋯Brδ−(ring) attraction has been the decisive energy contribution in the crystal of 1. [ABSTRACT FROM AUTHOR]

Two T‐shaped 14‐electron rhodium complexes 2 a and 2 b, "framed" and thus stabilized by PNP pincer ligands have been synthesized. The bis(t‐butyl)phosphine derived PNPtBu‐rhodium complex 2 a was isolated from pentane as the more stable cyclometalated Rh(III) hydrido complex and found to be in equilibrium with the T‐shaped 14e− Rh(I) complex 2 aT which itself could be directly crystallized upon change of the solvent. The cyclometallation is suppressed using an adamantyl substituted PNPAd ligand to give the analogous T‐shaped Rh(I) species 2 b, stabilized through an agostic interaction with one of the adamantyl C−Hs. Depending on the solvent, complex 2 a reacted with ethylene either by π‐coordination (4 a) or C−H activation giving a hydrido‐vinyl Rh(III) species 4 b, both isomers being in equilibrium in solution. Complex 2 b was found to reversibly C−H activate arenes to form the hydrido‐aryl Rh(III) complexes. [ABSTRACT FROM AUTHOR]

Zwei T‐förmige 14‐Elektronen‐Rhodiumkomplexe, 2 a und 2 b, wurden durch PNP‐Pincer Liganden „eingerahmt" und somit stabilisiert. Der Bis(t‐butyl)phosphin‐PNP‐Komplex 2 a wurde als stabilerer cyclometallierter Rh(III)‐hydrido‐Komplex aus Pentan isoliert, welcher sich im thermodynamischen Gleichgewicht mit dem T‐förmigen 14e− Rh(I)‐Komplex 2aT befindet, der selbst, bei Änderung des Lösungsmittels, direkt kristallisiert werden konnte. Die Cyclometallierung wird durch Verwendung des Adamantyl‐substituierten PNPAd‐Liganden unterdrückt, und die analoge T‐förmige Rh(I)‐Spezies 2 b erhalten, die durch eine agostische Wechselwirkung mit einem der Adamantyl‐C−Hs stabilisiert wird. Abhängig vom Lösungsmittel reagierte Komplex 2 a mit Ethylen entweder durch π‐Koordination (4 a) oder C−H‐Aktivierung, unter Bildung einer Hydrido‐Vinyl‐Rh(III)‐Spezies 4 b, wobei sich beide Isomere in Lösung im Gleichgewicht befinden. Komplex 2 b reagiert unter reversibler C−H Aktivierung mit Aromaten, wobei Hydrido‐Aryl‐Rh(III)‐Komplexe gebildet werden. [ABSTRACT FROM AUTHOR]

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An 11‐electron T‐shaped chromium(I) complex was obtained by reduction of a PNP‐supported chromium(II) iodide complex. Its d5 high‐spin electronic structure was characterized employing paramagnetic NMR, EPR, UV/Vis and magnetic measurements (SQUID). The complex readily reacts with conjugated dialkynes to cleave the internal C−C bond, forming the respective acetylide complexes. Varying the alkyne substituents enabled the isolation and characterization of dinuclear dialkynedichromium intermediates which thermally convert to the products. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Six‐vertex closo‐TeB5Cl5 (1) and twelve‐vertex closo‐TeB11Cl11 (2) telluraboranes have been prepared via co‐pyrolysis of B2Cl4 with TeCl4 in vacuo at temperatures between 360 °C and 400 °C. Both compounds are sublimable, off‐white solids, and they have been characterized by one‐ and two‐dimensional 11B NMR and high‐resolution mass spectroscopy. Both ab initio/GIAO/NMR and DFT/ZORA/NMR computations support octahedral and icosahedral geometries for 1 and 2, respectively, as expected due to their closo‐electron counts. The octahedral structure of 1 has been confirmed by single‐crystal X‐ray diffraction on an incommensurately modulated crystal. The corresponding bonding properties have been analyzed in terms of the intrinsic bond orbital (IBO) approach. 1 is the first example of a polyhedral telluraborane with a cluster size smaller than 10 vertices. [ABSTRACT FROM AUTHOR]

Die sechs‐ und zwölfgliedrigen polyedrischen Telluraborane closo‐TeB5Cl5 (1) und closo‐TeB11Cl11 (2) ließen sich ausgehend von einfachen, binären Molekülen in einem Eintopf‐Verfahren durch Co‐pyrolyse von B2Cl4 mit TeCl4 unter Vakuumbedingungen bei Temperaturen zwischen 360 °C und 400 °C herstellen. Die im Vakuum blass‐weiß sublimierbaren Verbindungen wurden mit Hilfe von ein‐ und zweidimensionalen 11B NMR und hochauflösender Massenspektrometrie charakterisiert. Sowohl Ab‐initio/GIAO/NMR‐ als auch DFT/ZORA/NMR‐Rechnungen untermauern die oktaedrischen bzw. ikosaedrischen Geometrien für 1 und 2, wie aufgrund der Anzahl der für closo‐Cluster typischen 2n+2 Gerüstelektronenzahl zu erwarten war. Die oktaedrische Struktur von 1 wurde durch Röntgenbeugung an einem inkommensurabel modulierten Kristall bestätigt. Die jeweilige Bindungssituation wurde mit Hilfe des IBO‐Ansatzes (Intrinsic Bond Orbital) analysiert. Clusterverbindung 1 ist das erste Beispiel für ein polyedrisches Telluraboran mit weniger als 10 Gerüstatomen. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new [PCCP]‐coordinated molybdenum platform comprising a coordinated alkyne was employed for the cleavage of molecular dinitrogen. The coordinated η2‐alkyne was left unaffected during this reduction. DFT calculations suggest that the reaction proceeds via an initially generated terminal N2‐complex, which is converted to a dinuclear μ‐(η1:η1)‐N2‐bridged intermediate prior to N−N bond cleavage. Protonation, alkylation and acylation of the resulting molybdenum nitrido complex led to the corresponding N‐functionalized imido complexes. Upon oxidation of the N‐acylated imido derivative in MeCN, a fumaronitrile fragment was built up via C−C coupling of MeCN to afford a dinuclear molybdenum complex. The key finding that the strong N≡N bond may be cleaved in the presence of a weaker, but spatially constrained C≡C bond contradicts the widespread paradigm that coordinated alkynes are in general more reactive than gaseous N2. [ABSTRACT FROM AUTHOR]