Synthesis of eta1-borazine complexes of palladium and platinum

The eta(1)-borazine complexes trans-[(Cy(3)P)(2)M(Br)(Br(2)B(3)N(3)H(3))] (Cy = cyclohexyl) were prepared by oxidative addition of a B-Br bond of (BrBNH)(3) to [M(PCy(3))(2)] (M = Pd, Pt). Furthermore the platinum compound was converted into the T-shaped cationic complex trans-[(Cy(3)P)(2)Pt(Br(2)B(3)N(3)H(3))][BAr(f)(4)] [Ar(f) = 3,5-(CF(3))(2)C(6)H(3)] by addition of Na[BAr(f)(4)].     

Synthesis of N-acyl-2-pyrrolidinones from the corresponding N-acyl-GABA derivatives

In this work, the synthesis of 1-(pyridine-3-carbonyl)pyrrolidin-2-one ( 1a ) and 1-(2-propyl-1-pentanoyl)pyrrolidin-2-one ( 1b ) by cyclization of the corresponding GABA derivatives, is reported. Two different methods are developed. For the synthesis of 1a , the parent molecule 4-[(pyridine-3-carbonyl)-amino]butanoic acid ( 2a ) is treated first with thionyl chloride and then with triethylamine. The second derivative, 1b , is produced by an intramolecular dehydration of 4-(2-propylpentanoylamino)butanoic acid ( 2b ) using an acid catalyst.     

Synthesis of a (thienylethenyl)benzimidazole platinum acetylide complex

A new platinum acetylide complex based on 6-dialkylaminobenzimidazol-2-yl-vinyl-2-thiophene-5-ylethyne was synthesized in seven steps and 2% overall yield.     

Synthesis of (-)-noviose from 2,3-O-isopropylidene-D-erythronolactol

Noviose is a key synthon for the construction of novobiocin, a clinically useful antitumor agent that has been shown to inhibit both type II topoisomerases and Hsp90. The synthesis of d-noviose from 2,3-O-isopropylidene-d-erythronolactol is described.     

Synthesis and characterization of a Schiff base derived from 2-aminobenzylamine and its Cu(II) complex: electropolymerization of the complex on a platinum electrode

A precursor (H₃A) was synthesized by the mono condensation of 2-aminobenzylamine with salicylaldehyde and then a tetradentade Schiff-base ligand (H₂L) prepared by using H₃A and 3-methoxysalicylaldehyde. The copper(II) complex of this new ligand was prepared and characterized by elemental analysis, electronic absorption, Fourier transform infrared (FT-IR), and magnetic susceptibility. For the ligand, ¹H- and ¹³C-NMR and liquid chromatography mass spectrometry (LC–MS) spectra were obtained. The tetradentate ligand is coordinated to Cu(II) through the phenolic oxygen and azomethine nitrogen. The use of this metal complex in the preparation of a modified electrode is also described. CuL was electropolymerized on a platinum electrode surface in a 0.1 mol dm^?3 solution of lithium perchlorate in acetonitrile by cyclic voltammetry between 0 and 1.6 V versus Ag/Ag⁺. Electrochemical properties of the electroactive polymeric film have been investigated and a surface confined polymerization mechanism was proposed.     

Synthesis of 2-isopropylidenehydrazinylthiazole and its subsequent annelation to the corresponding thiazolo[2,3-c]-s-triazole

An unequivocal synthesis of a new thiazolo[2,3-c]-s-triazole substituted at the C-5 position by a very useful methyl triphenylphosphonium salt has been achieved starting from the corresponding 2-isopropylidenehydrazinylthiazole and formic acid. Ring closure was found to be very easy without isolation of a formylhydrazino intermediate. The thiazole derivative was prepared from isopropylidenethiosemicarbazide and (3-chloro-2-oxo)propyltriphenylphosphonium chloride in a good yield.     

Synthesis and characterization of an iron(II) eta(2)-hydrazine complex

The iron phosphine complex cis-[Fe(DMeOPrPE)2(eta2-N2H4)][BPh4]2 {DMeOPrPE = 1,2-bis[bis(methoxypropyl)phosphino]ethane} was synthesized and structurally characterized. The structure exhibits the first eta2 coordination of hydrazine to iron, which may be relevant to intermediates trapped during nitrogenase turnover. The reaction of I with acid results in the formation of ammonia via a disproportionation reaction.     

Synthesis of a platinum(II) complex of chloroanilic acid

Conclusions A platinum(II) complex of chloroanilic acid was synthesized. This complex is isostructural to the analogous palladium complex and has the formula [Pt(C₆O₄Cl₂)Cl₂]K₂'H₂O.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2123–2124, September, 1986.The authors thank O. N. Krasochka for a preliminary x-ray diffraction analysis of this complex.     

Synthesis of 2-(5-halogeno-2-f uryl)-2,3-dihydroperimidines

By boiling naphthylene-1,8-diamine with 5-halogeno- and 5-nitrofurfural in benzene or xylene, 90–95% yields of the corresponding 2-(5-halogeno-2-furyl)- and 2-(5-nitro-2-furyl)-2, 3-dihydroperimidines have been obtained. The dehydrogenation of 2-(5-bromo-2-furyl)-2, 3-dihydroperimidine with palladium on carbon has given 2-(5-bromo-2-furyl)perimidine. The compounds obtained have been characterized by their UV and IR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1001–1003, July, 1973.     

Synthesis of a platinum(0) ethylene complex by the hydrazine method

Conclusions The (²-ethylene)-bis(triphenylphosphine)platinum(0) complex was obtained by the hydrazine method from (Ph₃P)₂PtCl₂ and ethylene in 2-propanol.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1188–1189, May, 1986.The authors thank P. V. Petrovskii for assistance in this work.     

Synthesis of the first 2,3-dihydro-1,2,3-azadiphosphete complex

Synthesis of the first 2,3-dihydro-1,2,3-azadiphosphete complex was achieved via thermal reaction of a 2H-azaphosphirene complex in o-xylene, whereby a 2,5-dihydro-1,3-diaza-2,5-diphosphinine complex and a further unidentified byproduct were formed; the structure of the title compound was established through an X-ray single-crystal diffraction study.     

Synthesis and characterization of a cationic ruthenium complex featuring an unusual Bis(eta2-BH) monoborane ligand

The reaction of Cp*Ru(P ( i )Pr 3)Cl with MesBH 2 (Mes = 2,4,6-trimethylphenyl), followed by chloride abstraction with LiB(C 6F 5) 4.2.5OEt 2 (LiBF 20), afforded the crystallographically characterized complex [Cp*Ru(P ( i )Pr 3)(BH 2Mes)] (+)B(C 6F 5) 4 (-); notably, this represents the first reported cationic complex to feature an eta (2)-BH monoborane ligand, as well as a rare example of bis(eta (2)-BH) ligation.     

An experimental and DFT computational study of a novel zerovalent tetracarbonyl tungsten complex of 2-(2′-pyridyl)quinoxaline

Synthesis and characterization of the new complex W(CO)₄(2,2′-pq), (1), where 2,2′-pq = 2-(2′-pyridyl)quinoxaline, is presented. The non-symmetric ligand 2,2′-pq belongs to the general class of quinoxalines, which are natural products yielding a rich coordination chemistry. Complex (1) crystallizes in space group P2_1/n with α = 9.601(6) Å, b = 16.735(11) Å, c = 10.315(8) Å, Z = 4 and V = 1616.0(19) Å³. Although its structure resembles those of W(CO)₄(phen) and W(CO)₄(bpy), some distortions that stem from 2,2′-pq’s asymmetry are present. DFT calculations reveal a ground state consisting of HOMO, HOMO − 1 and HOMO − 2, mainly of metal and carbonyl character, while LUMO is diimine oriented. The bonding scheme of (1) is illustrated after its consideration as been consisted by two fragments, namely W(CO)₄ and 2,2′-pq, acting as a donor and acceptor of electron density, respectively. In that scheme, back-bonding interaction of the main core to 2,2′-pq is mainly related to the mixing of HOMO − 2 from W(CO)₄ moiety with LUMO from 2,2′-pq moiety. The performed TDDFT calculations, not only in the gas phase but also combined with the conductor like polarizable continuum model (CPCM), reveal that the lowest in energy highly solvatochromic transition of (1) can be ascribed as a HOMO − 2 → LUMO transition and it is better described as MLCT/LLCT, underlying the CO → diimine contribution. The solvatochromic behaviour of (1) is anticipated by DFT/CPCM calculations and is probed in detail by absorption and NMR spectroscopy. The correlation of the lowest-energy-band maximum to the dipole moment of the corresponding solvents provides overall good linear fits, while the correlation to the dielectric constant affords good linear patterns only after the segregation of the solvents into groups. The ¹H NMR data of 2,2′-pq and (1) reveal an increase of the solvent influence to the chemical shifts of the diimine ligand after its coordination to the metal and suggest two different types of solvent-effects for the complex and the ligand, respectively. The observed proton shifts of (1) are related with the results of the Mülliken population analysis in solvents of different polarity; the transition from CCl₄ to MeOH seems to signify a charge transfer from the axial COs and the central metal to the equatorial COs and the internal nuclei of 2,2′-pq.     

Synthesis of 2-substituted-2,3- dihydro-1,4-dioxino[2,3-b]pyridine derivatives

[reaction--see text] A variety of 2-substituted-2,3-dihydro-1,4-dioxino[2,3-b]pyridines B have been synthesized from the readily available 2-nitro-3-oxiranylmethoxypyridine 1 via a Smiles rearrangement. We demonstrate how variations of reaction conditions affect the product distribution of A and B.     

Synthesis and characterization of a platinum(II) complex with N-acetyl-L-cysteine

Synthesis and spectroscopic studies in the solid-state of a platinum(II) complex with N-acetyl-L-cysteine are described. Elemental analyses are consistent with composition Pt₂(C₅H₈NO₃S)₄ · 3H₂O. Solid-state ¹³C NMR, infrared, and U-Vis spectroscopic results are consistent with coordination of the ligand to platinum(II) through sulfur. Thermal analyses confirmed water in the complex composition. Final residue of the thermal treatment was identified by powder X-ray diffractometry as metallic platinum.     

Unassisted eta2-coordination of polycyclic aromatic hydrocarbons to platinum(II)

The coordination of phenanthrene to the d8 Pt(II) center in (SP-4-2)-[Pt(C6F5)2(CO)(eta2-C14H10)] causes a slight pyramidalization at the metal-bound C atoms (C9 and C10), but no perceptible elongation of the corresponding C-C bond [C(13)-C(14) 132.0(5) vs. 133.8(5) pm in the free ligand].     

Dynamic equilibration of eta 1-carbene and eta 2-alkyne moieties within an alkynylcarbene dimanganese complex

The coordination of an additional [Cp(CO)2Mn] fragment to the alkyne linkage of an alkynylcarbene complex of the type Cp(CO)2Mn=C(R')C identical to CR" yields a highly fluxional molecule, in which the [eta 1-carbene] and [eta 2-alkyne] moieties are seen to exchange rapidly on the NMR time scale.     

C-H bond activation of arenes by a transient eta2-cyclopropene niobium complex

The intermolecular C-H bond activation of benzene occurs under very mild conditions (room temperature) via a rare stereospecific 1,3-H addition on an unsaturated eta2-cyclopropene intermediate generated by a beta-H abstraction of CH4 from TpMe2NbMe(c-C3H5)(MeCCMe) to give TpMe2NbPh(c-C3H5)(MeCCMe).