Double Metalation Research Articles

Concentration-Dependent Chemo- and Regioselective Metalation of 6,6′-Dibromo-2,2′-bipyridine

A reliable and synthetically useful strategy for the selective single or double metalation of 6,6'-dibromo-2,2'-bipyridine via lithium-halogen exchange is discussed. Experimental conditions for the optimal formylation of the singly and doubly lithiated intermediates are outlined as well as unequivocal X-ray crystallographic evidence for the regiochemistry of a competing deprotonation pathway.

Lithiation of tricarbonylchromium complexes with polyaromatic carbo-and heterocyclic ligands. DFT study

The reactions of tricarbonylchromium complexes of polyaromatic carbo-and heterocyclic derivatives with BunLi was studied by the density functional theory. The kinetic and thermodynamic factors for controlling the direction and selectivity of metallation were calculated for the model biphenylenetricarbonylchromium complex. Both approaches indicate that lithiation occurs exclusively at the aromatic ring bonded to the transition metal, which agrees with experimental data, while the selectivity inside this ring is determined more exactly by the thermodynamic factor. The solvation effects were simulated for the lithium salt of the tricarbonylnaphthalenechromium complex in which the lithium atom is localized in position 1 of the coordinated ring. The simulation showed the stable coordination of the lithium atom with two THF molecules, and the addition of the next THF molecule is thermodynamically unfavorable. The results of calculation of the relative energies for all possible THF-solvated lithium salts of the tricarbonylchromium complexes of biphenyl, naphthalene, biphenylene, and dibenzothiophene indicate that the difference in energies Δ E ≤ 1 kcal mol−1 corresponds to the experimentally observed absence of selectivity, while the difference more than 2.5 kcal mol−1 corresponds to the selectivity of the reaction. No additional coordination of the lithium atom to the free electron pair of the heteroatom was observed for the sulfur-containing dibenzothiophene complex. Similar calculations show that double metallation in the dibenzothiophene complex occurs at positions 1 and 4. The developed approach enables one to predict the direction and selectivity of metallation reactions of transition metal complexes with different arenes.

Molecular and Supramolecular Structures of 1‐Phenyl‐4‐phenylacetyl‐2‐thiosemicarbazide (H2L) and its Complexes with Diphenyllead(IV) Chloride and Acetate

AbstractReaction of 1‐phenyl‐4‐phenylacetyl‐2‐thiosemicarbazide (H2L) with diphenyllead(IV) dichloride and acetate afforded the complexes [PbPh2Cl2(H2L)2] and [PbPh2L]. The ligand and the complexes were characterized by elemental analyses, 1H and 13C NMR spectroscopy and X‐ray crystallography. In the asymmetric unit of crystals of the ligand there are four independent molecules of H2L and four molecules of water, which associate in the lattice as two independent sheets. The complex [PbPh2Cl2(H2L)2]·4MeOH has slightly distorted all‐trans octahedral geometry around the lead atom, and the fact that the ligand is S‐bound rather than O‐bound suggests that PbPh2Cl2 behaves as a “soft” Lewis acid. Hydrogen bonds involving NH groups, Cl atoms and MeOH molecules form a three‐dimensional supramolecular structure. In [PbPh2L]·Me2CO, the L2− anion bridges between two metal centres, binding to one strongly via the N and S atoms and weakly via the O atom, and to the other via the O atom, thus creating polymeric chains along the b axis. The double deprotonation and metallation of H2L induce significant changes in its configuration and lengthen the C‐S and C‐O bonds, suggesting an evolution of the dianion towards a thiol‐enol form.

Efficient Method for the Synthesis of Hetarenoindanones Based on 3‐Arylhetarenes and Their Conversion into Hetarenoindenes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Efficient method for the synthesis of diphosphine ligands with a heteroaryl–aryl bridge

A new efficient method for the synthesis of heteroaryl–aryl diphosphine ligands by direct double metallation of heteroaryl–aryls followed by phosphorylation of the resulting o, o′-dilithium salts is described. A number of new C 1-symmetric diphosphine ligands based on 3-arylheteroaryls, X-heteroaryls (X=N), and diphosphine ligands with a heterocyclic bridge with o-tolyl as the aryl fragment have been synthesized.

Efficient method for the synthesis of hetarenoindanones based on 3-arylhetarenes and their conversion into hetarenoindenes.

A series of hetarenoindanones have been prepared by direct double metalation of the appropriate 3-phenylhetarene with butyllithium in the presence of TMEDA followed by treatment of the resulting dilithium compound with ethyl N,N-dimethylcarbamate. All hetarenoindanones were reduced according to Wolff-Kishner by hydrazine in the presence of KOH to the corresponding hetarenoindenes.

The Superbase‐Mediated Pairwise Substitution of the 2,2′‐ and 6,6′‐Positions in a Biphenyl Derivative

AbstractThe superbasic mixture of butyllithium and potassium tert‐butoxide is powerful enough to enable the double proton abstraction from one ortho and one ortho′ position of 4,4′‐di‐tert‐butylbiphenyl. In this way, a series of functionalized derivatives becomes readily accessible, among them 4,4′‐di‐tert‐butylbiphenyldiyl‐2,2′‐dicarboxylic acid (2a) and 4,4′‐di‐tert‐butylbiphenyl‐2,2′‐diol (2d). The latter compound can be subjected again to a superbase‐promoted double metalation, thus giving rise to 2,2′,6,6′‐tetrasubstituted biphenyl derivatives. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Carbenes. Pincers, Chelates, and Abnormal Binding Modes

AbstractFor Abstract see ChemInform Abstract in Full Text.

Carbenes. Pincers, chelates, and abnormal binding modes

Abstract Routes to pincer and chelate carbene complexes of Pd, Rh, and Ir include double geminal CH activation, metallation, and CH activation. Abnormal binding via imidazole C5 can occur, and ion pairing can strongly influence C2 vs. C5 binding. Prior ligand binding via pyridine N before metallation is not essential. Computational methods are used extensively, for example, to compare N vs. C binding in imidazole. The possibility of C binding by histidine in metalloenzymes is discussed.

Double metallation of a molecular tweezers with chromium and visible light-induced metal transfer into the cavity

cis, exo-2-Phenyl-3-(2- E-phenylethenyl)norbornane reacts with Cr(CO) 6 to give mainly a bis-arene tricarbonylchromium complex. Under the influence of visible light, the latter undergoes conversion from externally to internally arene-bonded chromium carbonyl, with carbonyl displacement by the double bond, to form an η 6,η 2 metal-coordinated complex.

Titanocene complexes of ring-opened dibenzothiophene and related dimercaptobiaryl ligands

This paper describes organotitanium derivatives resulting from the reactions of titanocene dichloride with derivatives of dinenzothiophene (DBT). Lithium cleavage of DBT gives 2,2′-Li(LiS)C 12H 8 which reacts with (C 5H 5) 2TiCl 2 to give the metallacyclic complex (C 5H 5) 2TiSC 12H 8 (1). Two side products were isolated in smaller amounts, the thiolates (C 5H 5) 2Ti(SC 6H 4-2-Ph) 2 (2) and (C 5H 5) 2Ti(SC 6H 4-2-Ph)Cl. DNMR studies showed that 1 and its MeC 5H 4 analog 3 are stereochemically non-rigid as a result of the folding of the organosulfur chelate. The structure of (MeC 5H 4) 2TiSC 12H 8 was verified by single crystal X-ray diffraction; the complex consists of the expected (MeC 5H 4) 2Ti moiety coordinated to the carbon and sulfur of the ring-cleaved DBT. An attempt to generate 2,2′-Li(LiS)C 12H 8 via the double metalation of 2-phenylbenzenethiol with two equivalents of BuLi in the presence of TMEDA, followed by treatment with (C 5H 5) 2TiCl 2, gave the deep green complex (C 5H 5) 2TiS 2C 24H 16 (4). Single crystal X-ray diffraction indicated that 4 is a complex of the 2,2-dimercapto-3,3′-diphenylbiphenyl ligand (2,2′-(LiS) 2-3,3′-Ph 2C 12H 6), resulting from the coupling of two molecules of 1-Ph-2-LiS-3-LiC 6H 3. DNMR studies showed that this complex is stereochemically rigid. The free dithiol was liberated by treatment of 4 with anhydrous HCl. The complex of the unsubstituted 2,2′-dimercaptobiphenyl was prepared by treatment of 2,2′-Li(LiS)C 12H 8 with one equivalent of sulfur followed by quenching the reaction with titanocene dichloride to give (C 5H 5) 2TiS 2C 12H 8 (6). Electrochemical studies show that the Ti IV/III couple is reversible for all new compounds; the reduction potentials are lower for the chelating dithiolates and highest for the C-S chelate complexes 1 and 3.

Synthesis and molecular structure of dicarbaboryl ethenes and an unexpected dimetallated derivative

The first examples of molecules in which carbaborane clusters are linked via a simple CC double bond, and which constitute model compounds for boronated polydiacetylenes, are reported; double metallation of one of these molecules affords a unique closo–pseudocloso bis(carbametallaborane).

Dianions of 4-phenylbut-1-ene. Evidence for complex-induced proximity effects in the double metallation of hydrocarbons

Metallation of 2-methyl-4-phenylbut-1-ene 1 resulted in the formation of a dianion linearly conjugated with the phenyl ring rather than the cross-conjugated dianion often seen in these systems. Examination of the reaction mixtures at varying periods of time revealed that the initial deprotonation was not at the benzylic carbon. Complexation of n-butyllithium–tetramethylethylenediamine (TMEDA) with the aromatic ring of 1(a complex-induced proximity effect, CIPE) enhances the rate of metallation at the carbon β to the aromatic ring and α to the double bond of 1, as demonstrated in competitive metallations of 1 with ethylbenzene and of 1 with hexa-1,5-diene. This is the first report of a complex induced proximity effect in the double metallation of a hydrocarbon in which complexation occurred with the neutral hydrocarbon.

Unusual double palladium(II) cyclometallation in a tweezer-like receptor with stacked arms: synthesis, properties and X-ray structure

Double metallation of L1via aliphatic carbon and amide nitrogen atoms results in the formation of a tweezer-like molecule 1 with a four-membered [graphic omitted] ring and a helical configuration around the metal.

Controlled double metalation of coordinated dppm in manganese(I) complexes. The ligand [(PPh2)2C]2- as a building block in the syntheses of heterometallic species

Controlled double metalation of coordinated dppm in manganese(I) complexes. The ligand [(PPh2)2C]2- as a building block in the syntheses of heterometallic species

Carbene Osmium Complexes by Double Metalation of Alkoxylalkyl‐ and Aminoalkylphosphanes

Carbene Osmium Complexes by Double Metalation of Alkoxylalkyl‐ and Aminoalkylphosphanes

A double intramolecular ring metalation: formation, spectroscopic characterization, and molecular structure of (C5Me3(CH2)2)Ta(H)2(PMe3)2

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA double intramolecular ring metalation: formation, spectroscopic characterization, and molecular structure of (C5Me3(CH2)2)Ta(H)2(PMe3)2Steven T. Carter, William Clegg, Vernon C. Gibson, Terence P. Kee, and Robert D. SannerCite this: Organometallics 1989, 8, 1, 253–255Publication Date (Print):January 1, 1989Publication History Published online1 May 2002Published inissue 1 January 1989https://doi.org/10.1021/om00103a036RIGHTS & PERMISSIONSArticle Views71Altmetric-Citations16LEARN 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 (470 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Double oxidative addition reactions of aldehydes and ketones at triosmium clusters

Cyclohexanone (C 6H 10O) reacts with Os 3(CO) 12 in refluxing decane to give H 2Os 3(μ 3-C 6H 8O)(CO) 9, formed by double metallation (oxidative addition) at an α-CH 2 group of the ketone. Structurally similar products from phenol, phenyl-acetaldehyde or other aldehydes (described earlier) and from cyclohexenone are derived by reaction with Os 3(CO) 12 or H 2Os 3(CO) 10.