Ivan D. Grishin

Study of paramagnetic iron and ruthenium metallacarboranes using cyclic voltammetry and matrix-activated laser desorption/ionization time-of-flight spectrometry

The complex investigation of paramagnetic (17-electron) iron and ruthenium closo-metallacarboranes with chelate diphosphine ligands 3,3-(Ph2P(CH)nPPh2)-3-Cl-closo-3,1,2-MC2B9H11 (M = Fe, n = 2, 3; Ru, n = 4), o-phenylenecycloboronated 3-Cl-3,3,8- (n = 3, 4; R = H or Me), and bis(o-cycloboronated) (n = 4, 5) was performed using cyclic voltammetry and matrix-activated laser desorption/ionization time-of-flight (MALDI-TOF) spectrometry. Some diamagnetic iron and ruthenium exo-nido- and commo-complexes were studied using the same methods. A relationship between the redox potentials of the metallacarborane complexes and their stability and transformations under the MALDI-TOF conditions was established.

Amines as activators of the controlled polymer synthesis in the presence of ruthenacarboranes

Using polymerization of a series of acrylic monomers of various structure in the presence of ruthenium complexes as an example, it was shown that introduction of amines into the polymerization system allows to overcome one of the significant drawbacks of the controlled polymer synthesis under the radical initiation conditions, connected with the low rate of the polymerization. The influence of the amine nature on the peculiarities of the controlled polymer synthesis in the presence of ruthenacarboranes has been studied and amine was found to act as a reducing agent converting ruthenium in a complex to the lowest oxidation state and regenerating the true polymerization catalyst.

ATRP catalysed by ruthenacarboranes for successful synthesis of random and block-copolymers based on methacrylic monomers

The poly(methyl methacrylate) - based macroinitiator was successfully chain extended by isobornyl methacrylate, ethyl methacrylate and tert.-butyl methacrylate giving corresponding block-copolymers using catalytic system based on ruthenium carborane complex and isopropylamine. The polymerization proceeded smoothly in accordance with atom transfer radical polymerization mechanism giving polymers with predetermined molecular weights. A random copolymerization of methyl methacrylate, isobornyl methacrylate and tert.-butyl methacrylate was conducted using the same catalytic system. The measured glass transitions of obtained samples indicate dependences between polymer structure, composition and its properties.

Ruthenium carborane complexes: a relationship between the structure, electrochemical properties, and reactivity in catalysis of polymerization processes*

The ruthenacarborane complexes of the exo-nido- and closo-structure, namely, diamagnetic exo-nido-5,6,10-[RuCl(PPh3)2]-5,6,10-(μ-H)3-10-H-7,8-(CH3)2-7,8-C2B9H6, 3,3-[Ph2P(CH2)nPPh2]-3-H-3-Cl-closo-3,1,2-RuC2B9H11 (n = 4, 5), paramagnetic 3,3-[Ph2P(CH2)nPPh2]-3-Cl-closo-3,1,2-RuC2B9H11 (n = 2–5), and their some ortho-phenylenecycloboronated derivatives, were studied by cyclic voltammetry. All chelate closo-complexes are characterized by reversible redox transitions, while the exo-nido-complex is liable to irreversible oxidation. Shortening of the methylene link in the diphosphine ligand of closo-ruthenacarboranes and/or the introduction of ortho-phenylenecycloboronated moieties and methyl substituents to the carbon atoms of the {C2B9} ligand lead to a decrease in the redox potential and electron density redistribution to the metal atom. A comparison of the experimental results on methyl methacrylate polymerization in the presence of the catalytic systems based on the studied metallacarboranes with the data on their electrochemical characteristics suggests that the efficiency of using the ruthenium complexes as catalysts is mainly determined by steric factors.

Synthesis of metallacarborane ruthenium(ii) and ruthenium(iii) complexes with chelate 1,3-bis(diphenylphosphino)propane ligand and their mutual transformation in one-electron redox reactions

The first example of 12-vertex metallapolyhedra, namely, tris-phosphorus-containing closo-metallacarborane ruthenium(II) cluster , was synthesized and structurally studied. A principal possibility of the use of aliphatic amines as one-electron reducing agents converting carborane ruthenium(III) complexes to structurally close ruthenium(II) compounds was experimentally demonstrated.

Efficient methods for the preparation of bromine-containing exo-nido- and closo-ruthenacarborane clusters

An efficient method for the synthesis of bromine-containing exo-nido-clusters of a general formula exo-5,6,10-[Br(Ph3P)2Ru]-5,6,10-(μ-H)3-10-H-7,8-R2-nido-7,8-C2B9H6 (R = H, Me) was developed using the reactions of RuBr2(PPh3)3 with [K][7,8-R2-7,8-nido-C2B9H10]. Replacement of the phosphine ligands in the starting exo-nido-cluster (R = H) with the diphosphine ones afforded a series of diamagnetic (18-electron) closo-bromoruthenacarboranes, 3-Br-3,3-[κ2-Ph2P(CH2)nPPh2]-3-H-closo-3,1,2-RuC2B9H11 (n = 3−5). A mild thermal method of the halide ligands exchange (Cl → Br) upon heating of diamagnetic chlorine-containing complexes 3,3-[κ2-Ph2P(CH2)nPPh2]-3-H-3-Cl-closo-3,1,2-RuC2B9H11 (n = 3−5) with excess of CBr4 in benzene (70–80 °C) was suggested for the synthesis of paramagnetic (17-electron) bromine-containing ruthenacarboranes, 3-Br-3,3-[κ2-Ph2P(CH2)nPPh2]-closo-3,1,2-RuC2B9H11 (n = 3, 4) or 3-Br-3,3,8-[κ2-Ph2(CH2)5PPh]-μ-. Paramagnetic chlorine-containing clusters 3-Cl-3,3-[κ2-Ph2P(CH2)nPPh2]-closo-3,1,2-RuC2B9H11 (n = 2−4) were alternatively used as the starting compounds in the exchange reaction. Complexes with dppp and dppb (dppp is 1,3-bis(diphenylphosphino)propane, dppb is 1,4-bis(diphenylphosphino)butane) were used as examples to study the thermal reactions (toluene, 110 °C) leading in the presence of CBr4 to paramagnetic mono(P-o-phenylene)- and bis(P,P-o-phenylene)cycloboronated clusters, 3-Br-3,3,8-[κ2-Ph2(CH2)nPPh]-μ- and 3-Br-3,3,4,8-[κ2-Ph2(CH2)nP]-μ- (n = 3, 4). The compounds obtained were characterized by NMR spectroscopy (in the case of diamagnetic complexes), ESR spectroscopy and mass spectrometry (in the case of paramagnetic compounds). X-ray diffraction experiments were carried out for two cycloboronated paramagnetic complexes.

Substituted naphtholates of rare earth metals as emissive materials

The synthesis, characterization, photoluminescent (PL) and electroluminescent (EL) behavior of trivalent Sc, Nd, Gd, Er, Tm and Yb complexes with 3-(5-methylbenzoxazol-2-yl)naphthol (L-5Me) and 3-(6-methylbenzoxazol-2-yl)naphthol (L-6Me) ligands are reported. An X-ray analysis of Sc(L-5Me)3, Sc(L-6Me)3 as well as the non-methylated analogue Sc(L)3 has shown the monomeric structure of the complexes whereas the lanthanide naphtholates according to LDI-TOF data are dimers Ln2(L-5Me)6 and Ln2(L-6Me)6. The scandium complexes under photo- and electroexcitation revealed intense ligand-centered luminescence peaked at 522 nm. The PL and EL spectra of Nd, Tm and Yb compounds displayed moderate ligand-centered emission along with narrow bands of corresponding f–f transitions.

Mechanisms of Polymer Polymerization

This chapter is devoted to the observation of general methods of polymer synthesis including radical, ionic, coordination, and metathesis polymerization. The main advantages, possibilities, and drawbacks of each method are discussed. A special emphasis was placed to the modern methods of controlled polymer synthesis leading to well-defined polymers with desired structure, composition and properties. Such methods are considered as a way to the novel polymer materials for various high-tech applications.

Synthesis of a complex additive based on stearyl methacrylate and vinyl acetate for environmentally clean diesel fuel

An additive based on stearyl methacrylate–vinyl acetate copolymer was synthesized by the method of controlled atom transfer radical polymerization. The additive simultaneously improves the low-temperature properties of hydrotreated diesel fuels and enhances their resistance to thermal oxidation to meet the European quality standards. Comparative analysis of the effect exerted on the characteristics of environmentally clean diesel fuel by the synthesized additive and Dodiflow commercial depressor additive was made, and the negative effect of the latter on the thermo oxidative stability of diesel fuel was revealed of the fuel to thermal oxidation was revealed.

Specifics of luminescence of (benzoxazolyl)phenolate and (benzothiazolyl)naphtholate heterometallic Zn, Sc, Nd, Sm, Er, and Yb complexes

Heterometallic complexes Ln(L1)5Zn (Ln = Sc, Sm, Gd) were obtained by the reactions of silylamides Ln[N(SiMe)2]3 with 2-(benzoxazol-2-yl)phenol (HL1) in the presence of diethylzinc. Similar reactions with 3-(benzothiazol-2-yl)-2-naphthol (HL2) led to the formation of complexes Ln(L2)5Zn (Ln = Nd, Er, Gd, Yb). The introduction of the zinc-containing fragments provided a considerable increase of photo- and electroluminescence intensity of the scandium complex.