Synthesis and structure of 1,1′-bis(pentafluorophenyl)tetrahydrodigermane

Dehydrogenation of pentafluorophenylgermane in the presence of catalytic amounts of a Wilkinson complex, certain Rh^I ortho-benzosemiquinolate complexes, or (Ph₃P)₄Pt leads to tetrahydrodigermane, C₆F₅H₂GeGeH₂C₆F₅. X-ray analysis has confirmed thetrans-arrangement of the C₆F₅-cycles at the Ge atoms. The Ge-Ge bond length is 2.394(1) Å. The doublet pattern of the band due to the Ge-H bonds (v 2090 and 2104 cm^–1) in the IR spectrum is probably associated with nonequivalence of the hydrogen atoms in the molecule.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 315–318, February, 1994.     

Tin,palladium and platinum derivatives of 1,1′-bis(diphenylphosphine)ferrocene. Crystal and molecular structures of 1,1′- bis-(diphenylphosphine)ferrocenedichloropalladium(II) and of 1,1′-bis(diphenylphosphine)ferrocenedichloroplatinum(II)

Summary Ten derivatives of 1,1-bis(diphenylphosphine)ferrocene (BDPF) are described in this paper. The first three, [BDPF·SnCl₄] (1), [BDPF·MeSnCl₃] (2) and [BDPF·PhSnCl₃] (3), present the two phosphorus atoms of the ligand directly bonded to a Sn centre. Two others, [BDPF-PdCl₂ (4) and [BDPF·PtCl₂] (5), similarly have the ligand BDPF acting as a bidentate species towards a transition metal. The crystal and molecular structures of (4) and (5) are presented here. Two other BDPF complexes were obtained with Pd and Pt, with the transition metals in the zerovalent state, namely [Pd(BDPF)₂] (6) and [Pt(BDPF)₂] (7). Finally, three trimetallic complexes are also described; [BDPF·Pd(-Cl)₂SnCl₂] (8), [BDPF· Pt(-Cl)₂SnCl₂] (9) and [BDPF·PdClSnCl₃] (10).     

Synthesis and applications of (R)- and (S)-7,7′-dimethoxy-2,2′-bis(diphenylphosphino)-1,1′-binaphthalene

The synthesis of (R)- and (S)-7,7′-dimethoxy-2,2′-bis(diphenylphosphino)-1,1′-binaphthalene 5a and 5b is described. The phosphorus atoms in (S)-(−)-5b are shown to be slightly more basic than the phosphorus atoms in (S)-BINAP by comparing the magnitude of the ¹J (³¹P–⁷⁷Se) coupling constant in their respective diselenide derivatives. (S)-(−)-5b behaved similarly to (S)-BINAP in asymmetric Heck reactions.     

Synthesis and structures of 4,5-dimethyl-1,3-bis(pyridin-2-ylmethyl)-1H-imidazolium chloride and 1,1′-bis(pyridin-2-ylmethyl)-2,2′-bis(4,5-dimethylimidazole)

4,5-Dimethyl-1,3-bis(pyridin-2-ylmethyl)-1H-imidazolium chloride (1) was synthesized and characterized by IR and NMR spectroscopy and X-ray diffraction. An attempt to prepare the free tridentate N-heterocyclic carbene pincer ligand by the reaction of 1 with KN(SiMe₃)₂ resulted in the formation of 1,1′-bis(pyridin-2-ylmethyl)-2,2′-bis(4,5-dimethylimidazole) as a product of dimerization of the target carbene followed by the rearrangement accompanied by the elimination of dipyridylethane.

     

Synthesis,resolution and application of 2,2′-bis(di-2-furylphosphino)-1,1′-binaphthalene

A six step synthesis and resolution of (±)-2,2′-bis(di-2-furylphosphino)-1,1′-binaphthalene 4 (TetFuBINAP) is described along with its use in asymmetric inter- and intramolecular Heck reactions.     

Cyclic Voltammetry of 1,1′-bis(Diarylphosphino)metallocenes and Their Complexes with Palladium(II)

Cyclic voltammetry is used to study 1,1-bis(diarylphosphino)metallocenes (PP) [M(⁵-C₅R₄PAr₂)₂] (M = Fe; R = H; Ar = Ph, o-MeOC₆H₄, o-PrOC₆H₄, C₆F₅; M = Fe, R = Me, Ar = Ph; M = Ru, Os; R = H, Ar = Ph) and such Pd(II) complexes with these as neutral dichlorides [(PP)PdCl₂], dication solvates [(PP)Pd(L) _n ]²⁺ (L = H₂O, MeCN), and dication triphenylphosphines containing metal–Pd bond (PP)Pd(PPh₃)]²⁺. The nature of the metallocene metal atom and aryl substituents at phosphor atoms and the formation of a metal–Pd bond affect redox potentials of these compounds. 1,1-bis(Diphenylphosphino)metallocenes [M(⁵-C₅H₄PPh₂)₂] (M = Fe, Ru, Os) feature similar electron-donating properties. Oxidation potentials of Pd(II) complexes can serve as a criterion indicating the formation of a metal–Pd bond.     

Crystallographic and computational study of the structure of copper(II) 2,2′-bis(2-oxidobenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl

The reaction of M(OAc)₂ with 2,2′-bis(2-hydroxybenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl (H₂L1) allows the synthesis of 2,2′-bis(2-oxidobenzylideneamino)-4,4′-dimethyl-1,1′-biphenyl complexes of Cu(II) (CuL1), Co(II) (CoL1) and Ni(II) (NiL1) that were characterized by elemental analysis, FTIR spectroscopy and for CuL1 also by X-ray crystallography verifying a tetradentate binding mode of L1 via an (ONNO) motif of the two phenolic oxygen atoms and two azomethine nitrogen atoms. Recrystallization from a solvent mixture of dichloromethane and methanol promotes the formation of methanol adducts. Different binding modes of the methanol–complex were investigated using density functional theory calculations and binding energies, and thermodynamic data of the interaction are reported. The results show that the favored interaction occurs when the methanol molecule acts as a Lewis acid weakly binding via an O–H···O hydrogen bridge to a phenoxide moiety leading to an elongation of the respective M–O bond.

     

Synthesis of new 4,4′-bis(arylethynyl)benzophenones and 4,4′-bis(arylglyoxalyl)benzophenones based on chloral

4,4-Diiodobenzophenone was obtained by a three-stage synthesis from chloral and iodobenzene. 4,4-Bis(arylethynyl)benzophenones were synthesized by cross-coupling of 4,4-diiodobenzophenone with terminal arylethynes in the presence of a complex Pd catalyst; further oxidation of the products obtained in an iodine/DMSO medium afforded new bis(arylglyoxalyl)benzophenones.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 670–672, March, 1996.     

Synthesis of mono-and 1,1′-bis(3,4,4-trichlorobut-3-enoyl)-ferrocenes and 3,4,4-trichlorobut-3-enoylcymantrene

Friedel-Crafts acylation of ferrocene and cymantrene with 3,4,4-trichlorobut-3-enoyl chloride gave the corresponding trichloroallyl ferrocenyl and cymantrenyl ketones. The reaction with ferrocene involved either one or both cyclopentadienyl fragments, depending on the reactant ratio. The acylation of acetylferrocene with 3,4,4-trichlorobut-3-enoyl chloride afforded 1-acetyl-1′-(3,4,4-trichlorobut-3-enoyl)ferrocene.     

Structuresof 2,2′-bis(dimethylamino)biphenyl and its monohydrobromide)

In the context of ‘proton sponge’ systems, for the conformationally flexible biphenyl 1 the X-ray structure analysis as well as the basicity have been determined. 1 forms monoprotonated salts of which the structure of the hydrobromide 1a·BrX was solved. It contains a ‘proton sponge’-like N⋯H⋯N hydrogen bridge to which the 1000-fold increase of the basicity constant as compared to N,N-dimethylaniline is attributed.     

Synthesis and spectral properties of 3,3′-bis(dipyrrolylmethene)

Bis(2,4,7,8,9-pentamethyldipyrrolylmethene-3-yl)(4′-methoxyphenyl)methane dihydrobromide was synthesized and its spectral properties were studied. It was found that the basicity of the ligand 3,3′-bis-(dipyrrolylmethene) decreases upon insertion of the methoxyphenyl group in the 3,3′-spacer.     

Synthesis of 4,4′-bis(dichloroamino)- and 4,4′-bis(chloroamino)-3,3′-azofurazans,the first representatives of dichloroamino- and chloroaminofurazans

First representatives of dichloroamino- and chloroaminofurazans, viz., 4,4′-bis(dichloroamino)- and 4,4′-bis(chloroamino)-3,3′-azofurazans, were synthesized by the chlorination of 4,4′-diamino-3,3′-azofurazan with sodium hypochlorite in the CH₂Cl₂—H₂O mixture.     

Synthesis and properties of new functionalized poly(imides) based on 1,1-bis(4-aminophenyl)-1-z{4′-bis(4′’-bromophenyl)amino}phenyl-2,2,2-trifluoroethane

A new aromatic diamine, 1,1-bis(4-aminophenyl)-1-{4′-bis(4″-bromophenyl)amino}phenyl-2,2,2-trifluoroethane, is synthesized. Its interaction with various dianhydrides of aromatic carboxylic acids via high-temperature polycondensation yields a number of new functionalized poly(imides) combining high thermal and mechanical characteristics with solubility in organic solvents. The values of T _g vary from 208 to 230°C, and temperatures corresponding to 10% weight loss fall within the intervals 330–370 and 550–660°C (in air and argon, respectively). Spectroelectrochemical characteristics of poly(imides) are studied by cyclic voltammetry and UV-VIS spectrometry. Poly(imides) exhibit high reversible stability of electrochromic properties, and their color changes from colorless (the neutral form) to green (the oxidized form) as the applied potential is varied from 0 to 1.25 V.     

Synthesis and characterization of some ferrocene-containing telluroether ligands: crystal structure of 1,1′-bis(phenyltelluro)ferrocene

A series of five monodentate ferrocene tellurium ligands of the type Fe(C₅H₅)(C₅H₄TeR) and five bidentate 1,1′-disubstituted ferrocene tellurium ligands of the type Fe(C₅H₄TeR)₂ (R = Me, ⁿBu, C₆H₅, p-MeOC₆H₄, p-EtOC₆H₄) has been prepared by the reaction of 1,1′-dilithioferrocene with the appropriate ditellurides R₂Te₂. The ligands have been characterized by their elemental analyses, ¹H and ¹³C NMR spectra, mass spectra and cyclic voltammetry studies. The structure of Fe(C₅H₄TeC₆H₅)₂ has been determined by single-crystal X-ray diffraction study.     

Temperature dependences of the solubility of acetoacetylferrocene and 1,1′-bis(acetoacetyl)ferrocene in water-methanol mixed solvents

The solubility of β-dicarbonyl derivatives of ferrocene (acetoacetylferrocene and 1,1′-bis(acetoacetyl)ferrocene) in water-methanol binary solvents at various temperatures is investigated over a wide range of compositions of the mixed solvent. It is established that the solubility of these substances increases (especially, acetoacetylferrocene) with the temperature and methanol fraction in the solvent. It is concluded that the dissolution of the ferrocene β-diketones is accompanied by positive changes in enthalpy and entropy.     

Synthesis and spectral analysis of alkyl-substituted 3,3′-bis(dipyrrolylmethenes)

Four new alkyl-substituted 3,3′-bis(dipyrrolylmethene) dihydrobromides containing from 4 to 10 alkyl substituents were synthesized. In a highly alkylated ligand of these substances one of the hydrogen atoms of the 3,3′-methylene spacer was substituted with a phenyl group. The compounds obtained were studied by IR, ¹H NMR, electron absorption, and fluorescent spectroscopy. The increased alkylation degree of pyrroles and the introduction of an aryl substituent in the 3,3′-spacer causes a significant high-frequency shift of the N-H stretching vibrations in the IR spectra, an upfield shift of the NH-proton signals in 1H NMR spectra, a decrease in the auxochromic effects of protons on the aromatic system of chromophore in the composition of salts. The red shift of maximum of the strong band in electron absorption spectra and the emission spectra of compounds in DMF, DMSO, C₅H₅N, C₆H₆, and CHCl₃ was established. The salts obtained are stable in benzene and chloroform, while in electron-donor solvents the irreversible processes of solvolytic dissociation of salts to free organic base and HBr take place.     

Constants of keto-enol equilibrium of acetoacetyl- and 1,1′-bis(acetoacetyl)ferrocene in aprotic solvents at 20°

The keto-enol equilibrium of 2 × 10⁻³ M solutions of (acetoacetyl)ferrocene and 1,1′-bis(acetoacetyl)ferrocene was studied by ¹H NMR spectroscopy in a series of aprotic solvents such as DMSO-d ₆, (CD₃)₂CO, CDCl₃, CD₂Cl₂, CCl₄, and C₆D₆ at a temperature of 20°C. It was established that the calculated enolization constants increase with a decrease in the polarity of solvent molecules. The results complement and combine known empirical rules about the effect of the medium on keto-enol equilibria.     

Synthesis,Crystal Structure and Spectroscopic Properties of N,N′-Diphenyl-N,N′-bis(2-fluorophenyl)-1,1′-biphenyl-4,4′-diamine

A fluorinated tetraphenylbenzidine derivative, N,N′-diphenyl-N,N′-bis(2-fluorophenyl)-1,1′-biphenyl-4,4′-diamine (C36H26F2N2, Mr = 524.59) was synthesized via the palladiumcatalyzed Buchwald-Hartwig reaction of N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine with 2-fluoroiodobenzene (yield: 75%) and structurally characterized. It crystallizes in monoclinic, space group P21/n with a = 9.820(7), b = 14.305(11), c = 10.233(8) , β = 108.973(9)o, V = 1359.3(18) 3, Z = 2, Dc = 1.282 g/cm3, μ(MoKα) = 0.084 mm-1, F(000) = 548, S = 1.018, the final R = 0.0439 and wR = 0.0928. It presents a linear centrosymmetric framework constituted by a linkage of biphenyl as a bridge and two fluorinated diphenylamine moieties. The UV-Vis absorption and fluorescence spectra of the title compound were also investigated. This compound emits intense blue fluorescence with a peak wavelength of 406 nm in film.     

2,2′-Bipyridine-6,6′-bis(carbothioamide) metal complexes

Complexes of 2,2-bipyridine-6,6-bis(carbothioamide), obtained with a variety of metal cations, were characterised by microanalyses, molar conductivities and by i.r. and n.m.r. (for diamagnetic compounds) spectra. The iron(II) complex was also characterised by Mössbauer spectroscopy. The spectral data indicate that, in all cases, the ligand coordinates to the metal through one pyridine nitrogen and one sulphur.     

Role of the transition metal complexes of 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) in asymmetric catalysis

Metal complexes of 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) are being used as a chiral catalysts in many organic reactions. This review highlights recent developments on synthesis of metal BINAPs and its application in various organic synthesis. The studies done on the application of metal BINAPs show a unique reactivity, which enables its use in entirely different sets of chemical transformation.