Synthesis and Catalytic Properties of Novel Ruthenacarboranes Based on nido-[5-Me-7,8-C2B9H10]2− and nido-[5,6-Me2-7,8-C2B9H9]2− Dicarbollide Ligands

Abstract

The effect of methyl substituents in the lower belt of dicarbollide ligands on the redox potential of ruthenacarboranes based thereof, as well as the ability of the metallacarboranes obtained to catalyze radical polymerization with atom transfer were studied. For this purpose, a new approach to the synthesis of closo-ruthenacarboranes based on substituted dicarbollide ligands was developed and six new complexes 3,3-(Ph2P(CH2)4PPh2)-3-H-3-Cl-9-Me-12-X-closo-3,1,2-RuC2B9H9, 3,3,8-(Ph2P(CH2)4PPh-μ-(C6H4-o))-3-Cl-9-Me-12-X-closo-3,1,2-RuC2B9H8 and 3,3,4,8-(Ph2P(CH2)4P-μ-(C6H4-o)2)-3-Cl-9-Me-9-X-closo-3,1,2-RuC2B9H7 (X = H, Me) were synthetized and characterized by single crystal X-ray diffraction, NMR and ESR spectroscopy and MALDI TOF mass-spectrometry. Comparison of the values of the redox potentials of the synthesized ruthenium complexes in 1,2-dichloroethane with the values previously found for the corresponding ruthenacarboranes based on the parent dicarbollide anion showed that the introduction of methyl substituents into the carborane cage led to a decrease in the redox potentials of the complexes, which made them more preferable catalysts for ATRP. Test experiments on the polymerization of MMA showed that the synthesized ruthenacarboranes were effective catalysts for ATRP, the most active being the complex with two methyl groups and two ortho-phenylenecycloboronated fragments.

12-Vertex closo-3,1,2-Ruthenadicarbadodecaboranes with Chelate POP-Ligands: Synthesis, X-ray Study and Electrochemical Properties

“…The results of the performed electrochemical studies show that novel ruthenacarboranes with POP ligands generally similar to the earlier studied compounds based on bis(diphenylphosphino)alkanes [3][4][5][6], thus they should be capable to catalyze polymerization via ATRP mechanism. According to the measured values of potentials, Xantphos-based complexes seem to be the most prospective catalysts.…”

“…The polymerization was conducted in the presence of carbon tetrachloride as initiator. Isopropylamine was added as a reducing agent in accordance with Activators Generated by Electron Transfer (AGET) ATRP concept (Scheme 5) [3]. For precise dosage of initiator and decreasing the viscosity of the media toluene was added.…”

“…Ruthenium complexes with chelate organodiphosphine ligands of the general formula 3,3-(P-P)-3-Cl-closo-3,1,2-RuC 2 B 9 H 11 (P-P = PPh 2 (CH 2 ) n PPh 2 ) are interesting compounds which have found application in catalysis of Atom Transfer Radical Polymerization (ATRP) process [1][2][3]. The analysis of recent publications shows that redox properties of the complex and its catalytic activity dramatically depend on the bite angle of the corresponding diphosphine ligand.…”

Interligand Interactions in Half-Sandwich Nickelacarboranes with Phosphine Ligands: Away from Skeletal Rearrangements

“…Despite its more than 50 year history, the chemistry of nickelacarboranes has received much less development compared to the chemistry of cobalta- and ferracarboranes, which are characterized by the formation of extremely stable bis­(dicarbollide) complexes, − as well as the chemistry of rhoda- and ruthenacarboranes, , which are widely studied as catalysts for various processes. − This is largely due to the increased tendency of nickelacarboranes to skeletal rearrangements, − as well as the often uninformative 11 B NMR spectra of nickelacarboranes, which makes their identification problematic. Certain problems are also associated with the lack of methods for modifying nickel bis­(dicarbollide) and its reduced stability , compared to iron and cobalt bis­(dicarbollides).…”

Synthesis and Structural Characterization of p-Carboranylamidine Derivatives

“…Icosahedral closo-carborane cage compounds of the general composition C 2 B 10 H 12 can be viewed as 3D molecular analogs of benzene [1]. They are of high scientific and technological interest due to a variety of practical applications, e.g., in materials science [2][3][4][5][6][7][8][9][10][11][12][13], homogeneous catalysis [14][15][16][17][18][19][20][21], and medicinal chemistry [22][23][24][25][26][27][28][29]. Moreover, carborane derivatives are widely employed in coordination chemistry and as building blocks in supramolecular, bio-inorganic, and organometallic chemistry [30][31][32][33][34].…”