Z. A. Starikova

Synthesis of functional derivatives of the [3,3′-Co(1,2-C2B9H11)2]− anion

Abstract A series of various functional derivatives of the cobalt bis(1,2-dicarbollide) anion [8-XCH2CH2OCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)]− (X=OH, NH2, and CH(NH2)COOH) were prepared by the ring-opening reactions of [8-O(CH2CH2)2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] with different nucleophiles followed by functional group interconversion reactions. Acidic hydrolysis of [8-NCCH2CH2OCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)]− resulted in the shorter-chain alcohol [8-HOCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)]−. Structures of (Bu4N)[8-AcNHC(COOEt)2CH2CH2OCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] and [8-(1-C5H5N)CH2CH2OCH2CH2O-3,3′-Co(1,2-C2B9H10)(1′,2′-C2B9H11)] were determined by the single crystal X-ray diffraction method. Perspectives of application of functionalized cobalt bis(1,2-dicarbolide) derivatives in nuclear medicine are discussed.

Regioselective Fries Rearrangement and Friedel−Crafts Acylation as Efficient Routes to Novel Enantiomerically Enriched ortho-Acylhydroxy[2.2]paracyclophanes

Two useful approaches to ortho-acylhydroxy[2.2]paracyclophanes, starting from 4-hydroxy[2.2]paracyclophane, have been developed. TiCl4-catalyzed Fries rearrangement and direct acylation occur regioselectively (to the ortho position with respect to the hydroxy group), leading to 4-acetyl-5-hydroxy[2.2]paracyclophane (3) and 4-benzoyl-5-hydroxy[2.2]paracyclophane (4) in high to excellent chemical yields. For compound 4, an X-ray investigation has been performed. ortho-Acylhydroxy[2.2]paracyclophanes 3 and 4 have been obtained in enantiomerically enriched forms (ee 92−99%) and the absolute configurations of their enantiomers have been determined.

Novel chiral tridentate Schiff base ligands of the [2.2]paracyclophane series: synthesis and application

The first example of the efficient application of chiral tridentate N,O-[2.2]paracyclophane ligands of the imino type for enantioselective diethylzinc addition to aliphatic and aromatic aldehydes is presented. The enantiomeric excess of the resulted secondary alcohols is up to 93% e.e.

Dicationic triple-decker complexes with a bridging boratabenzene ligand

Abstract New dicationic triple-decker complexes with a bridging boratabenzene ligand [Cp*Fe(μ-η:η-C 5 H 5 BMe)ML]X 2 (ML=CoCp*, 6 (CF 3 SO 3 ) 2 ; RhCp, 7 (BF 4 ) 2 ; IrCp, 8 (CF 3 SO 3 ) 2 ; Ru(η-C 6 H 6 ), 9 (CF 3 SO 3 ) 2 ; Ru(η-C 6 H 3 Me 3 -1,3,5), 10 (CF 3 SO 3 ) 2 ; Ru(η-C 6 Me 6 ), 11 (CF 3 SO 3 ) 2 ) were synthesized by stacking reactions of Cp*Fe(η-C 5 H 5 BMe) ( 2 ) with the corresponding half-sandwich fragments [ML] 2+ . The structure of 10 (CF 3 SO 3 ) 2 was determined by X-ray diffraction study.

Synthesis and structure of rhodium complexes with monoanionic carborane ligand [9-SMe2-7,8-C2B9H10]−

Abstract (Rhodacarborane)halide complexes [(η-9-SMe 2 -7,8-C 2 B 9 H 10 )RhX 2 ] 2 ( 4a : X=Cl; 4b : X=Br; 4c : X=I), which are analogous to [Cp*RhX 2 ] 2 , were synthesized by reaction of (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(cod) (cod=1,5-cyclooctadiene) with HX. Compounds 4 were used to prepare several sandwich and half-sandwich complexes containing (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh fragment. 2e-Ligands destroy the dimeric structure of 4 to give the adducts (η-9-SMe 2 -7,8-C 2 B 9 H 10 )RhLX 2 , exemplified by preparation of (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(CO)I 2 and (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(PPh 3 )Cl 2 . The reaction of 4a with dppe in the presence of TlBF 4 affords the cationic complex [(η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(dppe)Cl]BF 4 ( 7 BF 4 ). Sandwich complexes [(η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(η-C 5 R 5 )]CF 3 SO 3 ( 11a CF 3 SO 3 : R=H; 11b CF 3 SO 3 : R=Me) were obtained by abstracting chloride from 4a by CF 3 SO 3 Ag with subsequent treatment with C 5 R 5 H. Complex 11b PF 6 was prepared by reaction of [Cp*RhCl 2 ] 2 with Na[9-SMe 2 -7,8-C 2 B 9 H 10 ]. Complex (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(η-7,8-C 2 B 9 H 11 ), containing two carborane ligands, was obtained by reaction of 4a with Tl[Tl(η-7,8-C 2 B 9 H 11 )]. Structures of 7 BF 4 and 11b PF 6 were confirmed by X-ray diffraction study.

Iron- and Ruthenium-Containing Triple-Decker Complexes with a Central Pentaphospholyl Ligand − X-ray Structures of [(η-C5H5)Fe(μ-η:η-P5)Ru(η-C5Me5)]PF6 and [(η-C5Me5)Ru(μ-η:η-P5)Ru(η-C5Me5)]PF6

Triple-decker cationic complexes with a central pentaphospholyl (pentaphosphacyclopentadienyl) ligand [Cp*M(μ-η:η-P5)M′(η-C5R5)]+ (3b: M = M′ = Fe, R = Me; 4a: M = Ru, M′ = Fe, R = H; 4b: M = Fe, M′ = Ru, R = H; 4c: M = Fe, M′ = Ru, R = Me; 5a: M = M′ = Ru, R = H; 5b: M = M′ = Ru, R = Me) were synthesized by exploitation of the stacking reactions of pentaphosphametallocenes Cp*M(η-P5) (1: M = Fe; 2: M = Ru) with half-sandwich fragments [(η-C5R5)M′]+. They were isolated as salts with BF4− or PF6− anions, and the structures of 4aPF6 and 5bPF6 were determined by X-ray diffraction. Triple-decker complexes with a central pentaphospholyl ligand are less reactive in nucleophilic degradation reactions than analogous complexes with C4Me4P and Cp* ligands in the bridging position. Only 4a and the previously known analogue 3a (M = M′ = Fe, R = H), containing the CpFe fragment, are nucleophilically destroyed by MeCN and NaI. The electrochemical properties of 2, 3a, 3b, 4a−c, 5a and 5b and the related cobalt-containing complexes [(η-C4Me4)Co(μ-η:η-P5)MCp*]+ (6: M = Fe; 7: M = Ru) were investigated. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

The structure of the crystal solvate of magnesium methoxide with methanol, Mg(OMe)2·3.5MeOH

Abstract The X-ray diffraction study of the crystals deposited from the solution obtained by the reaction of magnesium with methanol allowed the formulation of the product as Mg(OMe)2·3.5MeOH (I). Its structure is built of the residues of four types, namely cubane [Mg4(μ3-OR)4(OR)4(ROH)8] neutral molecules, [Mg4(μ3-OR)4 (OR)2(ROH)10]2+ cations, [(RO)2H]− anions (R = Me) and eight crystallographically independent non-coordinated solvating methanol molecules. All residues are linked into a three-dimensional framework by means of a complicated hydrogen-bonding system. The crystal structure provides the basis for discussion of the possible mechanism of desolvation of I.

Synthesis and derivatization of the 2-amino-closo-decaborate anion [2-B10H9NH3]-

Abstract A novel high-yield method of synthesis of the [2-B10H9NH3]− anion was elaborated. The method proposed includes reaction of the closo-decaborate anion with acetonitrile in the presence of acid, followed by hydrolysis of the formed nitrilium derivative [2-B10H9NCMe]− first to the acetamide derivative [2-B10H9NH2COMe]− and then to the amine. The crystal molecular structure of (Bu4N)[2-B10H9NHC(OH)Me] was determined by single crystal X-ray diffraction method. In the solid state, the acetamide derivative exists in the O-protonated tautomeric form and has a Z-configuration where the NH proton and the OH group are trans around the CN bond. The reaction of the [2-B10H9NH3]− anion with aromatic aldehydes in methanol in the presence of catalytic amounts of alkali gives N-protonated Schiff bases [2-B10H9NHCHR]− (R=C6H5, C6H4-2-OMe, C6H4-4-NHCOMe). Reduction of the Schiff bases with NaBH4 in aqueous methanol gives the corresponding monoalkylamino derivatives [2-B10H9NH2CH2R]− (R=C6H5, C6H4-2-OMe, C6H4-4-NHCOMe). The approach developed can be used in the synthesis of functional derivatives of the closo-decaborate anion for applications in nuclear medicine.

Synthesis and structure of biologically active ferrocenylalkyl polyfluoro benzimidazoles

Abstract The title compounds were synthesized in quantitative yields by interacting α-hydroxyalkyl ferrocenes with polyfluoroalkyl benzimidazoles in an aqueous-organic medium in the presence of HBF4. The resulting diastereomers and enantiomers were resolved using HPLC on silica bonded chiral stationary phases based on chiral cyclodextrins and cyclic antibiotics. The X-ray determination of molecular and crystal structure of 1-ferrocenylmethyl-2-(trifluoromethoxyfluoromethyl)benzimidazole (1) was carried out.

Stereoselective electrochemical transformation of alkylidenecyanoacetates and malonate into (E)-3-substituted-2-cyanocyclopropane-1,1,2-tricarboxylates

Abstract Electrolysis of malonate and alkylidenecyanoacetates in alcohols in the presence of sodium bromide in an undivided cell results in the stereoselective formation of (E)-3-substituted 2-cyanocyclopropane-1,1,2-tricarboxylates in 75–85% yields.