Insertion Of Rhodium Research Articles

Rhodium Complexes of a New-Generation Sapphyrin: Unique Structures, Axial Chirality, and Catalysis.

Rhodium insertion into the new 5,10,15,20-tetrakis(trifluoromethyl)sapphyrin was found to be much more facile than for other analogues, owing to NH⋅⋅⋅F hydrogen-bonding interactions that stabilise the pyrrole-inverted structure characteristic of the metallated product. The thus-obtained rhodium(I) complexes have axial chirality, and the enantiomers were resolved. The latter were found to interconvert quite rapidly in a process that involves a tautomerisation-like movement of the metal fragment between the five N atoms. The rhodium sapphyrins were investigated as catalysts for organic synthesis, by studying their carbene-transfer activity in the cyclopropanation of styrene with ethyl diazoacetate and comparing it to that of rhodium corroles.

Templated synthesis of catenanes incorporating Zn(II) or Rh(III)-complexed porphyrins: the coordination chemistry-only approach

Porphyrin-containing [2]catenanes were obtained from relatively simple organic precursors thanks to "coordination chemistry-only". When the central porphyrin metal is Zn2+ the [2]catenanes were assembled in two steps by using Cu(I)–N interactions to assemble acyclic complexes and Zn(II)–N interactions to generate rings. These sophisticated architectures were obtained in excellent yield since the formation of the thermodynamic products is favored over that of kinetic products. This also explains why a perfect fit in terms of distances and angles between the components to assemble leads to highly stable coordination chemistry-assembled species. When a second row metal with an inert coordination sphere, like Rh(III) was chosen as metal centre of the porphyrins, direct metalation of porphyrinic compounds with [Rh(CO)2Cl]2 was not met with success when the bidentate chelate used as connector was metal free. A three-step strategy was used for the synthesis of a tetra-rhodiumporphyrin[2]-catenane: (i) copper(I)-driven entwining of two free-base porphyrin-bearing bidentate chelates followed (ii) by insertion of rhodium in the porphyrin nuclei and finally (iii) cyclisation via formation of N-Rh coordination bonds.

ChemInform Abstract: Insertion of Rhodium into the Carbon-Sulfur Bond of Thiophene. Mechanism of a Model for the Hydrodesulfurization Reaction.

The reaction of (C 5 Me 5 )Rh(PMe 3 )(Ph)H with thiophene leads to the elimination of benzene and oxidative addition of the thiophene C-S bond across the Rh(I) center, giving (C 5 Me 5 )Rh(PMe 3 )(SCH=CHCH=CH). Similar reactions occur with 2-methylthiophene, 3-methylthiophene, 2,5-dimethylthiophene, benzothiophene, and dibenzothiophene. Selectivity studies performed with these complexes are consistent with the coordination of sulfur to rhodium prior to C-S bond cleavage. Reversible reductive elimination of thiophene occurs at ∼80°C. The diene portion of the C-S insertion ligand undergoes a Diels-Alder reaction with dimethyl acetylenedicarboxylate to give dimethyl phthalate as a major product

The dual role of Cu(i) as a protective group and a template in the synthesis of a tetra-rhodium(iii)porphyrin [2]catenane

A new [2]catenane containing four Rh(III) porphyrins has been prepared following a three-step strategy: (i) Cu(I)-driven entwining of two free base porphyrin-bearing bidentate chelates, followed by (ii) insertion of rhodium in the porphyrin nuclei, and finally (iii) cyclisation via the formation of N–Rh coordination bonds. Direct metalation of porphyrinic compounds with [Rh(CO)2Cl]2 was not met with success when the bidentate chelate used as a connector was metal free, thus making the Cu(I) protecting approach very attractive.

Formal Aromatic C−H Insertion for Stereoselective Isoquinolinone Synthesis and Studies on Mechanistic Insights into the C−C Bond Formation

Formal aromatic C-H insertion of rhodium(II) carbenoid was intensively investigated to develop a new methodology and probe its mechanism. Contrasting with the previously proposed direct C-H insertion, the mechanism was revealed to be electrophilic aromatic substitution, which was supported by substituent effects on the aromatic ring and a secondary deuterium kinetic isotope effect. Various isoquinolinones were synthesized intramolecularly via six-membered ring formation with high regio- and diastereoselectivity, while averting the common Buchner-type reaction. Intermolecularly, dirhodium catalyzed formal aromatic C-H insertion on electron-rich aromatics was also achieved.

Photochemical intermolecular C–H and C–F insertion of rhodium into pentafluoroanisole to generate a metallacycle; conversion to a cyclic carbene complex

Irradiation fo [(η5-C5H5)Rh(PMe3)(C2H4)] in pentafluoroanisole generates the metallacycle[(η5-C5H5)Rh(PMe3)[graphic omitted]F4]; reaction of this complex with 1 equiv. of Ph3C + PF6- at 220 K generates [(η5-C5H5)Rh(PMe3)[graphic omitted]F4]PF6.

Chemistry of a cofacial dirhodium diporphyrin: synthesis and reactivity of Rh2DPB

A novel cofacial dirhodium diporphyrin with a metal-metal single bond has been synthesized in two steps from the corresponding free base cofacial porphyrin H[sub 4]DPB. Rhodium insertion and subsequent photolysis yield the cofacial dirhodium diporphyrin Rh[sub 2]DPB. This cofacial dirhodium diporphyrin activates H[sub 2] with the assistance of ancillary ligands which attack the rhodium centers externally, weakening the metal-metal bond. The reaction of the dirhodium diporphyrin with H[sub 2] and CO yields the dirhodium diporphyrin dihydride Rh(H)Rh(H)DPB. The H[sub 2] cleavage reaction seems to occur within the cavity of the cofacial diporphyrin, on the basis of the unusually high T[sub 1] values of the resultant hydrides and the predicted regiospecific bonding pattern of additional, bulky ancillary ligands. This reactivity differs from that of a monomeric rhodium porphyrin system which gives a formyl complex. Phosphines have also been employed in reaction with the dirhodium diporphyrin and H[sub 2], resulting in a different type of hydride complex, seemingly one having three-center two-electron bonds. 25 refs., 8 figs., 1 tab.

Insertion of rhodium into the carbon-sulfur bond of thiophene. Mechanism of a model for the hydrodesulfurization reaction

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInsertion of rhodium into the carbon-sulfur bond of thiophene. Mechanism of a model for the hydrodesulfurization reactionWilliam D. Jones and Lingzhen DongCite this: J. Am. Chem. Soc. 1991, 113, 2, 559–564Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://doi.org/10.1021/ja00002a025RIGHTS & PERMISSIONSArticle Views625Altmetric-Citations128LEARN 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 (720 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Synthesis of metallacyclopentenones by insertion of rhodium into cyclobutenones

La reaction de cyclobutenones avec le complexe Cl Rh (PPh 3 ) 3 donne les complexes (η 2 -vinylcetene) rhodacyclopent-3-en-2-ones. Ces complexes subissent une reaction de substitution de coordinat avec Na Cp. On obtient le complexe(PPh 3 ) 3 1-η 5 -cyclopentadienyl-3,4-diethyl rhodacyclopent-3-en-2-one qui est etudie par diffraction RX. Les benzocyclobutenones reagissent avec ClRh (PPh 3 ) 3 pour donner 2 regioisomeres de rhodaindanones

α-(5,6-Dimethylbenzimidazolyl)rhodibamide and Rhodibinamide, the Rhodium Analogues of Vitamin B12 and Cobinamide

Abstract Monocyano-α-(5,6-dimethylbenzimidazolyl)rhodibamide, dicyano-α-(5,6-dimethylbenzimidazolyl)rhodibamide, and dicyanorhodibinamide have been prepared by insertion of rhodium into the metal-free analogue of vitamin B12 using rhodium carbonyl chloride. The monocyano form of the rhodium analogue of vitamin B12 was also obtained by treatment of the corresponding dicyano form with silver nitrate. The new compounds are characterized by their spectral and electrophoretic properties and their biological activity. While dicyano-α-(5,6-dimethylbenzimidazolyl)rhodibamide is biologically inactive, the corresponding monocyano form is active as antimetabolite to vitamin B12 in suppressing the growth of Lactobacillus leichmanii (ATCC 7830).