Metal-Induced B–H Activation in Three-Component Reactions: 16-Electron Complex CpCo(S2C2B10H10), Ethyl Diazoacetate, and Alkynes

Tungsten carbonyl σ-complexes with C-thioethers based on 9-Me3N-7,8-C2B9H11

Complexation of tungsten carbonyl moieties with C- and C,C-methylthio-derivatives of charge-compensated nido-carborane.

Reactivity Modes of Cp*M-Type Half-Sandwich Dichalcogenolate Complexes with 2,6-Disubstituted Aryl Azides: The Effects of the Metal Center, Chalcogen, and Ligand Moiety on Product Formation

Cp*M-type half-sandwich dichalcogenolate complexes bearing either carborane or benzene moieties show diverse reactivity patterns toward two selected 2,6-disubstituted aryl azides under thermal or photolytic conditions. The chalcogen (S and Se) has little effect on the formation of final products. However, the effects of both the metal center and the ligand moiety of the metal precursor on the reactions were significant. Compared to iridium precursor Cp*IrS₂C₂B₁₀H₁₀ (1a), rhodium and cobalt analogues (1b: Cp*RhS₂C₂B₁₀H₁₀, 1c: Cp*CoS₂C₂B₁₀H₁₀) demonstrated no reactivity toward aryl azides. The reaction of Cp*IrSe₂C₂B₁₀H₁₀ (1d) with 2,6-Me₂C₆H₃N₃ led to the clean formation of complex 2 with C(sp³)-H activation of one methyl group of the Cp* ligand and loss of N₂ along with the rearrangement of the benzene ring of the original azide ligand, whereas the treatment of Cp*IrS₂C₆H₄ (1e) with 2,6-Me₂C₆H₃N₃ under the same reaction conditions gave a 16-electron half-sandwich complex 5 featuring C-N coupling on one methyl group from the Cp* ligand. When 2-Me-6-NO₂C₆H₃N₃ was employed, the same reaction patterns for forming products (3 and 6) with the nitro group migrating to the para-position versus the original aryl azide were observed. In addition, the reaction with metal precursor 1d generated another product 4 featuring the exchange of nitro and azido groups, while the reaction with 1e afforded another complex 7 with the formation of the N-NO₂ moiety. All new complexes were characterized by spectroscopy methods, and single-crystal X-ray analyses were performed for complexes 2 and 5-7. Furthermore, radical mechanisms for the formation of complexes 2-7 were proposed.

Iridium-induced regioselective B–H and C–H activations at azo-substitutedm-carboranes: facile access to polynuclear complexes

Iridium-induced selective C–H and B(2,3)–H bond activations have been achieved atm-carboranes featuring azobenzene directing groups. A series of mononuclear, dinuclear and trinuclear complexes have been obtained.

Syntheses and crystal structures of [IrIII{C(CHCO2Et)(dppm)2-κ4 P,C,C',P'}ClH]Cl·2.75CH2Cl2 and its derivatives, [IrIII{C(CHCO2Et)(dppm)2-κ4 P,C,C',P'}(CH2CO2Et)Cl]Cl·CH3OH·0.5H2O, [IrIII{C(CHCO2Et)(dppm)2-κ4 P,C,C',P'}Cl2]Cl·CH3OH·2H2O and [IrIII{C(CHCO2Et)(dppm)2-κ4 P,C,C',P'}(CH2CO2Et)(CO)]Cl2·2CH2Cl2·1.5H2O

The common feature of the four iridium(III) salt complexes, (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}(eth-oxy-oxoethanyl-idene)methane-κ4 P,C,C',P')chlorido-hydridoiridium(III) chloride methyl-ene chloride 2.75-solvate (4), (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}(eth-oxy-oxoethanyl-idene)methane-κ4 P,C,C',P')chlorido-(eth-oxy-oxoethanido)iridium(III) chloride-methanol-water (1/1/0.5) (5), (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}(eth-oxy-oxoethanyl-idene)methane-κ4 P,C,C',P')di-chlorido-iridium(III) chloride-methanol-water (1/1/2) (6) and (bis-{[(di-phenyl-phosphan-yl)meth-yl]di-phenyl-phosphanyl-idene}(eth-oxy-oxoethanyl-idene)methane-κ4 P,C,C',P')carbon-yl(eth-oxy-oxoethanide)iridium(III) dichloride-meth-yl-ene chloride-water (1/2/1.5) (7) or in terms of their formulae [Ir(C55H50O2P4)ClH]Cl·2.75CH2Cl2 (4), [Ir(C4H7O2)(C55H50O2P4)Cl]Cl·CH3OH·0.5H2O (5), [Ir(C55H50O2P4)Cl2]Cl·CH3OH·2H2O (6) and [Ir(C4H7O2)(C55H50O2P4)(CO)]Cl2·2CH2Cl2·1.5H2O (7) is a central IrIII atom coordin-ated in a distorted octa-hedral fashion by a PCCP ligand system and two additional residues, such as chlorides, a hydride, a carbonyl or an alkyl unit. Thereby, the PCP pincer ligand system and the residue trans to the carbodi-phospho-rane (CDP) C atom surround the iridium(III) transition metal in the equatorial plane under the formation of two five-membered dissimilar chelate rings [C-CCDP-P (4, 5, 6 and 7) for the first ring: 120.2 (3), 121.9 (5), 111.2 (3) and 121.7 (2) °; for the second ring: 112.1 (3), 113.5 (5), 120.5 (3) and 108.3 (2)°]. A cyclo-propane-like heterocycle is positioned approximately orthogonal (84.21-88.85°) to the equatorial plane, including an alkyl-idene bridge connecting the IrIII atom and the coordinating CDP atom of the PCP subunit. In general, the neutral PCCP ligand system coordinates the metal in a tetra-dentate way via three Lewis acid/base bonds and by an alkyl-idene unit presenting strengthened inter-actions. In all the crystal structures, (disordered) solvent mol-ecules are present in the voids of the packed mol-ecules that inter-act with the positively charged complex and its chloride counter-ion(s) through weak hydrogen bonding.

Regioselective B-H/C-H activation and metal-metal bond formation induced by half-sandwich metals complexes at hydroxy-substituted o-carboranes

A binuclear iridium complex, (Cp2*Ir2(CH2O)C2B10H8) (6), with a unique metal-metal bond has been synthesized and fully characterized. Importantly, this complex is constructed via selective C-H and B(3)-H bond activation on the carborane precursor. Additionally, when the proligand (2-pyridine)(o-carboranyl)methanol ligand was combined with a half-sandwich iridium complex, selective B(6)-H bond activation or metal-carbon bond formation can be induced by the use of different bases. And the rhodium complex constructed from (2-pyridine)(o-carboranyl)methanol ligand containing a metal-carbon bond has been obtained and fully characterized.

B–H functionalization of the monocarba-closo-dodecaborate anion by rhodium and iridium catalysis

The regioselective derivatization of the monocarba-closo-dodecaborate anion via catalytic B–H bond activation is reported.