The synthesis of N-heterocyclic carbene-diphosphine macrocycles by metal template assisted cyclization reactions has been explored. Attempts to prepare the facial tungsten tricarbonyl precursor complex containing an NH,NH-functionalized carbene and a suitable diphosphine resulted in displacement coordinated isolation corresponding tetracarbonyl [3]. Re(I) chloro bearing ligand [5] can be prepared is for subsequent formation intermediate [H(2)-6]Cl reactive 2-fluoro substituents at...

The carbene derived from (1R,3S)-camphoric acid was used to prepare the borane adduct with Piers' 7. Subsequent hydride abstraction gave borenium cation 8. Adducts 9-BBN and corresponding acid-derived bearing increasingly sterically demanding N-substituents (R = Me 9, Et 10, i-Pr 11) cations 12-14 were also prepared. These not active as catalysts in hydrogenation, although 9-11 shown undergo ring expansion reactions at 50 °C give species 15-17. IBOX-carbene precursors 18 19 amino alcohols...

Azolium precursors to expanded-ring NHCs incorporating a chiral bicyclic skeleton derived from (1R)-camphor with N,N′-dibenzyl or N,N′-dipyridyl substituents have been prepared and used for the synthesis of number metal complexes resultant NHCs. The framework contains two fused rings, one which is seven-membered while other six-membered. Deprotonation (1R,5S)-2,4-dibenzyl-1,8,8-trimethyl-4-aza-2-azoniabicyclo[3.2.1]oct-2-ene hexafluorophosphate, 1a·HPF6, produces solution "free carbene", 1a,...

Abstract A series of well‐defined copper(I) complexes bearing ring‐expanded N‐heterocyclic carbene (NHC) ligands has been applied to the azide–alkyne cycloaddition reaction. The obtained results notably showed that six‐membered NHC outperform well‐established five‐membered ones. [CuI(Mes‐6)] displayed a remarkable catalytic activity while respecting strict criteria for click reactions.

Recent developments in main group chemistry towards the activation and conversion of N2 have lead to revelation that boron can greatly affect these processes. Boron is capable acting both as a borane Lewis acid activate metal-N2 complexes an ambiphilic borylene able free N2. The latter example accepting donating electron density manner reminiscent transition metal systems containing filled empty d-orbitals.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Occurrence of Anhydrides in the Pyrolysis Monocarboxylic Acids1David Davidson and Paul NewmanCite this: J. Am. Chem. Soc. 1952, 74, 6, 1515–1516Publication Date (Print):March 1, 1952Publication History Published online1 May 2002Published inissue 1 March 1952https://pubs.acs.org/doi/10.1021/ja01126a048https://doi.org/10.1021/ja01126a048research-articleACS PublicationsRequest reuse permissionsArticle Views204Altmetric-Citations25LEARN ABOUT THESE...

A series of 12 silver(I)–N-heterocyclic carbene (NHC) complexes were prepared featuring five- (both saturated and unsaturated backbone), six-, seven-membered ring ligand scaffolds. The N-substituents the NHCs diisopropylphenyl in all cases, while anion was varied between bromide, acetate, triflate. evaluated as catalysts spirocyclization 1-(1H-indol-3-yl)-4-phenylbut-3-yn-2-one to give a spirocyclic indolenine product. To our knowledge, it is first time that systematic study has been...

The reactions of propargyl amides, ureas, carbamates, and carbonates with B(C6F5)3 proceed via an intramolecular 5-exo-dig cyclization across the alkyne unit to yield corresponding vinyl borate species. generated sp2 carbocation is stabilized by flanking heteroatoms, allowing for isolation oxazoline intermediates. fate these intermediates strongly dependent upon propargyl-functionalized starting material, carbamates undergoing a ring-opening mechanism (propargyl rearrangement) give cyclic...

Iron(II) templates based on a [(eta(5)-Cp(R))Fe]+ core have been employed for the successful synthesis of 1,4,7-triphosphacyclononane derivatives (9-aneP3R'3) from range appropriately functionalized coordinated diphosphines and monophosphines. 1,2-Diphosphinoethane (1,2-dpe) or (2-phosphinoethyl)phenylphosphine (Phdpe) undergo base-catalyzed Michael-type addition to trivinylphosphine, divinyl(benzyl)phosphine, divinyl(phenyl)phosphine in [(eta(5)-Cp(R))Fe(diphosphine)(monophosphine)]+...

The base-catalyzed cyclization of 1,2-bis(phosphanyl)ethane with trivinylphosphane on a pentamethylcyclopentadienyl iron template results in the high-yield synthesis first triphosphacyclononane derivative containing one vinyl-functionalized and two secondary phosphanes. vinyl is readily hydrogenated alkylated to give tritertiary 1,4,7-triethyltriphosphane macrocycle 1.

A tridentate N^C^N ligand, 1, containing a bicyclic central NHC ring and two flanking pyridyl groups has been coordinated to Rh(I) Ir(I) give complexes of the type [M(κ(3)-1)(1,5-COD)]PF(6) (2 M = Rh; 3 Ir). In contrast our earlier study with this have shown approximate trigonal bipyramidal geometry in solid state exist as an isomeric mixture solution determined by (1)H (13)C NMR spectroscopy. Electrochemical studies revealed that both undergo 1-electron oxidation potential Rh complex 0.1 V...

A diphosphine ligand (1·HPF(6)), which is a potential precursor to PC(NHC)P pincer, with backbone containing two phenylene groups and central bicyclic 4-aza-2-azoniabicyclo[3.2.1]oct-2-ene unit has been synthesised coordinated Pd(II) Pt(II) give trans-[M(κ(2)-P,P'-)Cl(2)]PF(6) where M = Pd (2) or Pt (3a). Single-crystal structure determinations of 2 3a show the complexes be isostructural in trans-spanning fashion amidinium being protonated non-coordinated. react CH(3)I dimers...

The alkoxycarbonyl complexes Pd(Ph2Ppy)2(CO2R)(OAc) where Ph2Ppy is 2-pyridyldiphenylphosphine and R = Me 1, Et 2, i-Pr 3 have been prepared from Pd(OAc)2 in ethanol solution under an atmosphere of CO. Increasing the CO pressure favours formation palladium carbonyl species. In presence 2 mol equivalents CF3CO2H, complex Pd(Ph2Ppy)2(CO2CH3)(CF3CO2) 4 isolated methanol. Pd(Ph2Ppy)2(CO2CH3)Cl 5 has obtained by reaction Pd(Ph2Ppy)2Cl2 with NaOCH3 1 crystallographicaly characterised as trans...

The radical-induced cyclization of 1,2-bis(phosphanyl)ethane and diallylphenylphosphane coordinated to a (pentamethylcyclopentadienyl)iron(II) template gives the first ten-membered triphosphorus macrocycle with three inequivalent phosphorus centers [Eq. (1); AIBN=azobisisobutyronitrile].

An unusual example of diastereoselectivity has been observed in Cu(κ(3)-P,C,P'-1)X complexes where 1 is an asymmetric tridentate ligand containing a bicyclic NHC framework and X halide. When Cl(-), the S(Cu) isomer formed selectively whereas when = I(-) R(Cu) diastereomer preferred.

A series of alkynyl aryl conjugated aldehydes and imines were prepared their adducts with various Lewis acidic boranes have been studied via NMR, absorption, luminescence spectroscopies in solution. The imine-B(C6F5)3 adduct showed remarkable solution stability, was then trialled vapochromism experiments using simple impregnated paper strips to examine the fluorescence responses.

Bicyclic expanded ring carbenes show increased sterics compared to similar monocyclic derivatives. The enhancement is a consequence of an impacting methyl substituent.

The controlled formation of mixed-metal bimetallics was realised through use a

The zerovalent complexes Pd(Ph2Ppy)31 and Pd(Ph2Ppy)2(dba) 2, where Ph2Ppy is diphenyl-2-pyridylphosphine dba = trans,trans-dibenzylideneacetone, have been synthesized characterised. Reactions of 1 with alkynes studied the dimethyl acetylenedicarboxylate complex Pd(Ph2Ppy)2(η2-DMAD) 3, DMAD acetylenedicarboxylate, isolated structurally trans-Pd(Ph2Ppy)2(PhCCH2)X, X CF3CO2−4 or Cl−5, trans-Pd(Ph2Ppy)2{CO(CH3)CCH2}Cl 6 result from oxidative addition phenylacetylene/CF3CO2H,...

The complex [(η5-Me3SiC5H4)Fe(10aneP3-H2,C2H3)]+, where Me3SiC5H4 is trimethylsilylcyclopentadienyl and 10-aneP3-H2,C2H3 1-vinyl-1,4,8-triphosphacyclodecane, has been prepared by the base-catalyzed template cyclization of 1,3-bis(phosphino)propane (1,3-bpp) trivinylphosphine (tvp) at metal center. A related radical-initiated iron-template reaction between 1,2-bis(phosphino)ethane (1,2-bpe) triallylphosphine (tap) gave [(η5-C5Me5)Fe(Me-10aneP3-H2,C3H5)]+, C5Me5...

The ability of alkali metal complexes featuring functionalized BINOL-derived ligands to catalyze ketone hydroboration reactions was explored. reduced products were formed in excellent yields and with variable enantioselectivities dependent upon the nature ligand cation.

The stoichiometric reaction of diphenyl-2-pyridylphosphine (Ph2PC5H4N-2) and palladium(II) acetate afforded the palladium(I) dimer [Pd2(µ-Ph2PC5H4N)2(OAc)2] 1. Attempts to isolate monomer, [Pd(µ-Ph2PC5H4N)2(OAc)2], from 2∶1 stoichiometry reactions (Ph2PC5H4N∶Pd), resulted only in isolation When >3 mole equivalents Ph2PC5H4N were used zerovalent palladium complex [Pd(Ph2PC5H4N)3] was isolated. Other dimers with carboxylic or sulfonic anionic ligands have been prepared by a metathesis...

Palladium(II) and platinum(II) complexes of a chiral pentacyclic phosphine, (1S, 4R, 4aS, 5aR, 6R, 9S, 9aS, 10aR)-4,6,11,11,12,12-hexamethyl-10-phenyl-dodecahydro-1,4:6,9-dimethano-phenoxaphosphinine (phenop), show diverse structures dependent upon the chosen metal-containing starting material reaction conditions. With palladium acetate, P,C-cyclometallated dimeric complex [Pd(μ-κ2-OAc)(μ-κ1-OAc)(κP,κC14-phenop)]2, 4, is obtained through metallation at C(14) methyl to form six-membered...

Nine-membered 1,4,7-triphospha- and triarsamacrocycles with unsaturated benzo-backbones have been prepared using the [CpRFe]+ unit as a template. The cyclisation involves attack of coordinated phosphide (or arsenide) nucleophile at an activated, electrophilic ortho-fluorophenyl substituent on neighbouring pnictide donor. macrocycle assembly is 2 + 1 type where two new chelate rings are formed from appropriately derivatised bidentate monodentate phosphines/arsines. Both [(η5-C5H5)Fe]+...