The alkylidyne bridged compounds [(cb)(2)M(mu-CSiMe3)(2)M(cb)(2)] (1a, M = Nb; 1b, M = Ta; cb = carbazole) react thermally with one equivalent of alkynes EtC=CEt and Me3SiC=CH to produce new organometallic derivatives 2 and 3, respectively. The molecular structures of 2 and 3 are shown to consist of non-planar six-membered di-metallacycles originating from insertion of an alkyne unit into one of the alkylidyne bridges of 1. Treatment of 1b with 3,5-di-tert-butyl-2,6-diphenylphenol (ArOH) leads to the mono-phenoxide [(ArO)(cb)Ta(mu-CSiMe3)(2)Ta(cb)(2)] 4. Treatment of 4 with Me3SiC=CH leads to the corresponding metallacycle [(ArO)(cb)Ta(mu-CSiMe3){mu-C(SiMe3)}Ta(cb)(2)] 5. Structural parameters for 2b, 3a, 3b and 5 obtained by X-ray diffraction show delocalization is present with four equivalent M-C and two equivalent C-C distances. The non-planar structure is best described as a twist of the planar [M(mu-C)-M] and [C-C-C] units within the ring. The non-planar structure of 2a and 2b is maintained in solution as evidenced by diastereotopic methylene protons for the CH2CH3 substituents. At elevated temperatures coalescence to a simple A(2)B(3) pattern is observed. From the coalescence temperatures of 328 K for 2b an activation barrier of 16.1(5) kcal mol(-1) can be estimated for the adoption of a planar structure. The insertion of Me3SiC=CH produces a 2.4,6-substitution pattern for 3a, 3b and 5 with the 5-H (beta to two metal centers) being downfield shifted to delta 8.43 (3a), 8.64 (3b) and 9.03 ppm (5). (C) 1998 Elsevier Science Ltd. All rights reserved.

Insertion eines Alkins in eine Metall‐μ‐Alkyli‐din‐Bindung führte zu den sechsgliedrigen Dimetallacyclen 1 und 2 (M = Nb, Ta), bei denen – vor allem im Fall von 2 – spektroskopische und strukturelle Daten für eine Formulierung als Dimetallabenzol‐Derivate sprechen. cbH = Carbazol.magnified image

Der η2‐Iminotitan‐Komplex 1 reagiert mit Azobenzol in Gegenwart von Pyrrolidinopyridin py] unter Ligandenaustausch zum Komplex 2, der sich bei 100°C innerhalb mehrerer Tage in den Phenylimidotitan‐Komplex 3 umwandelt. Die Ti‐N‐Bindung in 3 ist 171.9(3) pm lang, und der Ti‐N‐C‐Winkel beträgt 173.1(3)°. Anders als Imidozirconium‐Verbindungen, die leicht unter C‐H‐Aktivierungen reagieren, ist 3 ein „toter Hund”︁ – selbst bei 110°C keine Reaktion in Benzol! Ar′ = 2,6‐iPr2C6H3, R′ = tBu.magnified image

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and structure of five-coordinate aryl-imido derivatives of zirconium(IV)Robert D. Profilet, Cesar H. Zambrano, Phillip E. Fanwick, John J. Nash, and Ian P. RothwellCite this: Inorg. Chem. 1990, 29, 22, 4362–4364Publication Date (Print):October 1, 1990Publication History Published online1 May 2002Published inissue 1 October 1990https://doi.org/10.1021/ic00347a005RIGHTS & PERMISSIONSArticle Views162Altmetric-Citations53LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (419 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Metal ion complexes of the thiosemicarbazone,4N-cyclohexyl-2-[1-(2-pyridinyl)ethylidene]hydrazinecarbothioamide (HL4CH), have been prepared and spectrally characterised. Both the size of the cyclohexyl-group attached at4N as well as the4N hydrogen affect the stoichiometry and stereochemistry of the isolated complexes. The large cyclohexyl-group evidently causes the isolation of [Fe(HL4CH) (L4CH)H2O](ClO4) instead of the expected [Fe(L4CH)2]ClO4[Co(L4CH)Br] instead of [Co(HL4CH)Br2], and [Ni(L4CH)Br] instead of [Ni(HL4CH)2Br2]. The presence of the hydrogen at4N presumably hinders the deprotonation of HL4CH on complex formation since [Cu(HL4CH)Cl2] was isolated rather than [CuLCl], which occurs when the thiosemicarbazone has4N with two alkyl groups or incorporated in a ring. Further, although we prepared [Ni(L4CH)Br], complexes of this stoichiometry are planar and diamagnetle when4N does not have a hydrogen(s) attached to it rather than tetrahedral and paramagnetic as has been found for the present complex.

A series of cobalt(II), nickel(II) and copper(II) complexes of 2-picolinamineN-oxide, HA, has been prepared. Solids of formula [M(HA)3](BF4)2 (M=cobalt(II) or nickel(II); [Cu(HA)2]X2 (X=BF 4 − , NO 3 − ); [Co(HA)2X2] (X=Cl− or Br−); [Ni(HA)2Cl2] and [Cu(HA)X2] (X=Cl− or Br−] have been isolated and characterized by partial elemental analyses, molar conductivities, magnetic susceptibilities, DSC-TGA, and spectral methods. All complexes were found to be monomeric, and their spectral parameters are compared with those of the metal ion complexes ofN-alkyl-2-picolinamineN-oxides, 2-dialkylaminopyridineN-oxides and 2-picolinamine. The cobalt(II) and nickel(II) halide complexes spectrally show a mixture of octahedral and tetrahedral centres.