The geometries and relative stabilities of the singlet and triplet states of phenyl- (Cs), diphenyl- (C2), 1-naphthyl- (Cs), di(1-naphthyl)- (C2), and 9-anthryl-substituted (Cs) carbenes were investigated at the B3LYP/6-311+G(d,p) + ZPVE level of density functional theory. The singlet-triplet energy separations (DeltaEST), 2.7, 2.9, 3.4, 3.7, and 5.7 kcal/mol, respectively, after including an e...

The performance of a set mono- and bimetallic Rh(i) Ir(i) complexes bearing carbene-linker-carbene (CXC) bis-triazolylidene ligands (with X = O, N) coordinated in bridging or chelating fashion was evaluated the hydrothiolation alkynes.

Reaction of CsOH with triazolium salts affords mesoionic compounds containing an exocyclic oxygen; the same product is obtained by reaction of the corresponding Cu(I) triazolylidenes with CsOH and represents an unusual reactivity pattern of N-heterocyclic carbene precursors that has implications for carbene copper-catalyzed reactions.

Porphyrin rhodium(III) complexes accommodate one or two NHC ligands in the apical position, which leads to severe porphyrin distortion and dearomatization. The strain in the bis(carbene) complex induces facile carbene dissociation and the formation of a catalytically active site for alcohol oxidation.

The synthesis and characterisation of a thallium(I) triscarbene complex of the chelating, tripodal carbene ligand 1,3,5-[tris(3-tert-butylimidazol-2-ylideno)methyl]-2,4,6-trimethylbenzene is reported, in which the thallium ion is coordinated by three N-heterocyclic carbene donors in a distorted trigonal planar environment.

In an effort to develop new tripodal N-heterocyclic carbene (NHC) ligands for small molecule activation, two new classes of tripodal NHC ligands TIME and TIMEN have been synthesized. The carbon-anchored tris(carbene) ligand system TIME (R = Me, t-Bu) forms bior polynuclear metal complexes. While the methyl derivative exclusively forms trinuclear 3:2 complexes [(TIME)2M3] 3+ with group 11 metal ...

Phomactins are novel platelet activating factor (PAF) antagonists isolated from the culture of marine fungus Phoma sp.1 Members of the phomactin family share a unique [9.3.1] pentadecane ring system, and their biosynthetic pathway shares a branchpoint with the taxane family of natural products.1,2 Substantial synthetic efforts have been described in the literature toward the synthesis of severa...

The iridium(Ir) (triNHC = tri-N-heterocyclic carbene)-catalyzed transfer hydrogenation of glycerol carbonate (GC) is described in the absence additional hydride sources. reduction provides a sustainable route to produce industrially-valuable formate and lactate with high turnover numbers (TONs). bimetallic Ir(I) involving triNHC carbene ligands exhibits TONs, reaction mechanism, including Ir(tr...

The synthesis of a ruthenium complex containing an N-heterocylic carbene (NHC) and a mesoionic carbene (MIC) is described wherein addition of a Brønsted acid results in protonolysis of the Ru-MIC bond to generate an extremely active metathesis catalyst. Mechanistic studies implicated a rate-determining protonation step in the generation of the metathesis-active species. The activity of the NHC/...

Tungsten complex with a coordinated 2-azidoethyl isocyanide ligand reacts with PMe3 at the azido function to give a complex with a coordinated iminophosphorane which upon hydrolysis of the P=N bond yields a complex with an NH,NH-stabilized N-heterocyclic carbene ligand, 7; alkylation of the carbene ring nitrogen atoms gives a complex with an N,N'-dialkylated imidazolidin-2-ylidene ligand, 8 .