Alexander F. Smol'yakov

Chiral octahedral complexes of Co(III) as catalysts for asymmetric epoxidation of chalcones under phase transfer conditions

Stereochemically inert and positively charged chiral complexes of Co(III) were shown to catalyze the asymmetric epoxidation of chalcones with H2O2 under phase transfer conditions. The reaction products had enantiomeric purities of up to 55%. It was also shown that complex 1a I− catalyzed the coupling reaction of a resulting epoxide with CO2 (conversion 72%).

Remarkable Structural and Electronic Features of the Complex Formed by Trimeric Copper Pyrazolate with Pentaphosphaferrocene

According to spectroscopic (NMR, IR, UV/Vis) study, the interaction of pentaphosphaferrocene [Cp*Fe(η(5) -P5 )] with trimeric copper pyrazolate [(Cu{3,5-(CF3 )2 Pz})3 ] yields a new compound that is astonishingly stable in solution. Single-crystal X-ray analysis reveals unprecedented structural changes in the interacting molecules and the unique type of coordination [Cp*Fe(μ3 -η(5) :η(2) ,η(2) -P5 ){Cu(3,5-(CF3 )2 Pz)}3 ]. As a result of the 90° macrocycle folding, the copper atoms are able to behave both as a Lewis acid and as a Lewis base in the interaction with the cyclo-P5 ligand.

Role of basic sites of substituted ferrocenes in interaction with the trinuclear 3,5-bis(trifluoromethyl)pyrazolates: thermodynamics and structure of complexes

Formation of complexes of the macrocycles (ML)3, where L = 3,5-(CF3)2Pz = 3,5-bis(trifluoromethyl)pyrazolate, M = Cu and Ag, and the acylferrocenes FcC(O)CH2R (Fc = (C5H5)Fe(C5H4); R = H (1), Ph (2)) was studied by means of variable temperature IR, UV-vis, NMR spectroscopy. The sole site of coordination in solution is the oxygen atom of the CO group. The complex composition (1 : 1) and thermodynamic parameters in hexane solution were determined, the formation constants and the enthalpies decreasing from 1 to 2 and from Ag to the Cu macrocycle. The same coordination site featuring triple coordination of oxygen to all metal atoms of a macrocycle was found in the solid state by single crystal X-ray diffraction. There are no shortened contacts of the metal in the macrocycles with π-electron system of the ferrocenes cyclopentadienyl ligands in all complexes. The complexes of (ML)3 with 1 have 1 : 2 composition and bipyramidal structure whereas 2 forms the 1 : 1 complex with (AgL)3. The latter is packed in the infinite stacks involving additional contacts with Ph groups.

An unusual conversion of paramagnetic [3-Cl-3,3,8-{Ph2P(CH2)nPPh-µ-(C6H4-ortho)}-1,2-(CH3)2-closo-3,1,2-RuIIIC2B9H8] (n=3 and 4) to form the first 18-electron P-phenylene ortho-cycloboronated closo-ruthenacarboranes with a dioxygen ligand.

Treatment of [3-Cl-3,3,8-[Ph2P(CH2)nPPh-µ-(H8] (1, n = 3; 2, n = 4) with an excess of KOH in a 1:1 benzene/methanol mixture at room temperature in air affords new dioxygen closo-ruthenacarborane complexes [3-(η2-O2)-3,3,8-[Ph2P(CH2)nPPh-µ-(H8] (3, n = 3) and (4, n = 4) in 42.5% and 45.8% yield respectively. The structures of dioxygen complexes 3 and 4 were established by single-crystal X-ray diffraction. The IR and multinuclear NMR data [1H, 13C{1H}, 31P{1H} and 11B{1H}] along with 2D HSQC correlation spectra for the new dioxygen closo-ruthenacarboranes are discussed.

Aerobic Co or Cu/NHPI-catalyzed oxidation of hydride siloxanes: synthesis of siloxanols

A highly efficient preparative method for the synthesis of siloxanols based on aerobic Co(OAc)2 or Cu(OAc)2/NHPI-catalyzed oxidation of hydride siloxanes using “green”, commercially available, simple inexpensive reagents and mild reaction conditions has been proposed. This is a general reaction for the synthesis of mono-, oligo- and polymeric siloxanols with various structures (linear, branched and cyclic).

Self-Assembled Ionic Composites of Negatively Charged Zn(salen) Complexes and Triphenylmethane Derived Polycations as Recyclable Catalysts for the Addition of Carbon Dioxide to Epoxides

The design and synthesis of a novel type of self‐assembled ionic composite composed of negatively charged Zn(salen) complexes and triphenylmethane derived polycations is reported. These composites were applied as easily recyclable catalysts for carbon dioxide addition to epoxides. The composites functioned as bifunctional catalysts which could be easily separated and recycled by precipitation from the reaction mixture upon addition of tetrachloromethane. The same batch of the catalyst could be employed for, at least, five runs with its catalytic properties improving as it was reused. A fully heterogeneous system was also prepared by cross‐linking leuco dye with para‐dibromoxylene and adding to it calculated amounts of Zn(salen) complex. The heterogeneous system was catalytically competent in the reaction between styrene oxide and carbon dioxide and its activity also increased on its reuse.

Synthesis and molecular structure of a manganese tricarbonyl complex based on 5,6- nido -C 2 B 8 H 12 carborane

The anionic manganese tricarbonyl complex [1,1,1-(CO)3-isonido-1,2,4-MnC2B8H10]–was synthesized in the form of PPN and tmdaH salts (PPN is bis(triphenylphosphine)iminium, tmda is N,N,N’,N’-tetramethyl-1,8-diaminonaphthalene) by the reaction of the deprotonated form of the medium-size non-icosahedral carborane 5,6-nido-C2B8H12 with Mn(CO)5Br. The structure of the complex [tmdaH][1,1,1-(CO)3-isonido-1,2,4-MnC2B8H10] was deter-mined by X-ray diffraction.

Crystal structure of μ-carbonyl-1:2κ2C:C-carbonyl-1κC-(1η5-cyclo­penta­dien­yl)iodido-2κI-[μ-2-(pyridin-2-yl)ethene-1,1-diyl-1κC1:2κ2N,C1]ironpalladium(Fe—Pd) benzene monosolvate

The title binuclear μ-pyridylvinylidene FePd complex (FePd1) was obtained from Cp(CO)2FeI and 2-ethynylpyridine in diisorpopylamine in the presence of PdCl2