Transition metal complexes with heterocyclic analogs of fluorene. 1. Synthesis, structures, and haptotropic rearrangements of tricarbonylchromium complexes of dibenzothiophene

The complex formation of dibenzothiophene with chromium carbonyl complexes of the general formula L₃Cr(CO)₃ (L = Py, NH₃, or CO) afforded ⁶-C₁₂H₈SCr(CO)₃ (1). In the presence of tetramethylethylenediamine, complex 1 was selectively metallated with BuLi at position 4 of the coordinated ring to form ⁶-4-LiC₁₂H₈SCr(CO)₃ (2). In decane, the tricarbonylchromium group is reversibly and intramolecularly migrates from the unsubstituted to substituted ring due to the inter-ring haptotropic rearrangement (IRHR) at 130 °C for 100 h. In decane, the rate constant of IRHR was estimated experimentally by ¹H NMR spectroscopy and theoretically by the density functional theory (DFT).     

Tricarbonylchromium complexes with phenalene. Synthesis, structure, and thermal rearrangements

The reaction of phenalene with Cr(CO)₃Py₃/BF₃·OEt₂ afforded a mixture of two isomeric complexes, tricarbonyl(6a,7-9,9a,9b-·⁶-phenalene)chromium (1) and tricarbonyl(3a,6a,9b,4-6-·⁶-phenalene)chromium (2). Deprotonation of the mixture of compounds1 and2 followed by treatment with MeI, BuⁿI, or D₂O gave complexesexo-1-R-1 (3–5: R=Me (3), Buⁿ (4), or D (5)). The molecular geometry of complex3 was established by X-ray structural analysis. Heating of complex5 in toluene or C₆F₆ at 90–110 °C resulted in redistribution of deuterium among positionsexo-1,endo-1, and 3 in the resulting complexes of types1 and2 via sigmatropic shifts of the H _exo and H _endo atoms in the nonaromatic ring as well asvia inter-ring migrations of the tricarbonylchromium group. In the case of3, the methyl label is distributed among positionsexo-1 and3 to form isomeric complexes with similar structures (exo-1-Me-2 (6), 3-Me-2 (7), and 3-Me-1 (8), respectively)via processes analogous to those observed in the case of isomerization of compound5 (except for migration of the H _exo atom). The mechanisms of these rearrangements are discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1863–1880, October, 1997.     

Mononuclear and binuclear tricarbonylchromium complexes of aryl-substituted [2.2]paracyclophanes

The complexation reactions of monoaryl- and diaryl-substituted [2.2]paracyclophanes with (NH₃)₃Cr(CO)₃ have been studied. The aromatic rings of [2.2]paracyclophane are more favorable for coordination than aryl substituents. This leads to the regioselective formation of the corresponding mono- or binuclear tricarbonylchromium complexes. In some cases, the tricarbonylchromium group is coordinated to the aryl ring of the substituent to form (in low yields) the corresponding mononuclear complex or binuclear complexes with both the aromatic ring of paracyclophane and the aryl ring of the substituent involved in coordination. The structure of such complex, namely, [4-(η⁶-2,4,6-trimethylpheny)-11-16-η⁶-[2,2]paracyclophane]bis[tricarbonylchromium(0)] was confirmed by X-ray diffraction study. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 142–150, January, 1998.     

Synthesis,structure, and NMR spectra of a new ferrocenylbenzene tricarbonylchromium complex

Complex 1 (1,2,4-triferrocenylbenzene tricarbonylchromium), possessing four heterometals, has been synthesized efficiently by a new method in one pot. Through detailed study on the NMR chemical shifts of 1 and the ligand 2, the NMR chemical shifts of 1 shift upfield from those of 2. The NMR spectra of 1 have reduced magnetic anisotropy of benzene after Cr(CO)₃ coordination with 2. The ferrocenyl groups have electron donating effect on the central benzene ring of 1.     

Synthesis,molecular structure and biological activity of Niii complexes based on substituted 2-(2-hydroxyphenyl)benzoxazole

New Niⁱⁱ complexes based on the substituted 2-(2-hydroxy-phenyl)benzoxazole have been synthesized from the corresponding ligands and nickel acetate. The crystal structure of bis[2-(1,3-benzoxazol-2-yl-κN)-4,5-dichloro-3-(methoxycarbonyl)phenolate-κO]nickel(ii) has been determined by X-ray diffraction. The new Niⁱⁱ complexes have been screened for their antibacterial, protistocidal and fungistatic activities     

Benzoyl-substituted (η-arene)tricarbonylchromium complexes: Synthesis and structure

Lithiation of chloro- and methoxy-(η⁶-benzene)tricarbonylchromium complexes yielded, after electrophilic quench with a Weinreb amide, the corresponding benzoyl-substituted complexes. One of them has been investigated by an X-ray diffraction study.     

Synthesis and structures of boron complexes of acyl hydroxy coumarins

New boron chelates were synthesized by the reactions of 3-acetyl-4-hydroxycoumarin and 8-acyl-7-hydroxy-4-methylcoumarins with boron trifluoride etherate and hydroxybenzodioxaborole. The structure of 3-acetyl-4-difluoroboryloxycoumarin containing an intramolecular C=O...B coordination bond was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2012–2015, November, 2006.     

Synthesis and photochromic properties of tricarbonylchromium complexes of 2H‐η6‐benzochromenes

Although in the 2H‐chromene (benzopyran) series complexation with tricarbonylchromium, under thermal conditions, is totally regioselective, in the naphthopyran series the same reaction cannot be observed. We show here that with tricarbonyl(trispyridine)chromium as complexing agent, in the presence of Lewis acid, complexation of naphthopyrans can be achieved and is totally regioselective. The complexes formed are photochromic compounds, and their thermal bleaching kinetic constants are reduced as compared with the non‐complexed homologous compound. Copyright © 2000 John Wiley & Sons, Ltd.     

Synthesis,characterizations and crystal structures of new antimony (III) complexes with dithiocarbamate ligands

Eight new antimony (III) complexes containing dithiocarbamate ligands (R₂NCS₂)₂SbBr [R₂NCS₂ = OC₄H₈NCS₂ (1), C₂H₅NC₄H₈NCS₂ (2), Me₂NCS₂ (3), C₄H₈NCS₂ (4)] and (R₂NCS₂)₃Sb[R₂NCS₂ = C₅H₁₀NCS₂ (5), Bz₂NCS₂ (6), Et₂NCS₂ (7), (HOCH₂CH₂)₂NCS₂ (8)] have been synthesized by the reactions of antimony (III) halides with dithiocarbamate ligands in 1:2 or 1:3 stoichiometries. All the complexes have been characterized by elemental analysis, melting point as well as spectral [IR and NMR (¹H and ¹³C)] studies. The crystal structures of complexes 1, 5 and 8 have been determined by X-ray single crystal diffraction, and their electrochemical character has also been studied.     

Synthesis and structure of a new zirconium phosphate with double-stranded chains

The zirconium phosphate [Zr(HPO₄)(PO₄)F₂] · 1.5H₂en was prepared, and its structure was determined by X-ray diffraction analysis.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1897–1901, November, 1994.The work was carried out with financial support from SERC (UK) and the National Foundation of Natural Sciences (China).     

Synthesis,structure and properties of some copper(II) complexes containing an ONO donor Schiff base and substituted imidazole ligands

Five new mixed ligand coper(II) complexes, viz. [Cu(SAA)(H₂O)] (1), [Cu(SAA)(MeImH)] (2), [Cu(SAA)(EtImH)] (3), [Cu(SAA)(BenzImH)] (4) and [Cu(SAA)(MebenzImH)] (5), where SAA = salicylideneanthranilic acid, MeImH = 2-methylimidazole, EtImH = 2-ethylimidazole, BenzImH = benzimidazole, MebenzImH = 2-methylbenzimidazole, have been synthesized and characterized by means of elemental analysis, FAB mass spectrometry, magnetic susceptibility, X-band EPR, electronic spectroscopy, IR and cyclic voltammetry. The frozen solution EPR spectra of the complexes have shown axial features. Single crystal X-ray analysis of 2 and 3 has revealed the presence of a distorted square planar geometry (N₂O₂) in the complexes. The superoxide dismutase (SOD) activity of the present complexes has also been measured and discussed.     

Synthesis and structure of new dinuclear palladium complex containing no bridging ligands

Oxidation of the mononuclear semiquinonediimine complex [(NPh)(NH)C₆H₄]₂Pd with silver trifluoromethanesulfonate afforded the diamagnetic dinuclear dicationic palladium complex {[(NPh)(NH)C₆H₄]₂Pd}₂(O₃SCF₃)₂ with a Pd...Pd distance of 3.267(1) . The complex was structurally characterized, and its spectroscopic and electrochemical properties were studied.     

Synthesis and characterization of some new mononuclear ruthenium complexes containing 4-(un)substituted dipyridylpyrazole ligands

A mononuclear ruthenium complex [Ru(bpy)₂(bpp)](PF₆) (1) and its halogenated and nitro derivatives [Ru(bpy)₂(Xbpp)](PF₆) (bpy = 2,2′-bipyridine; bpp = 3,5-bis(2-pyridyl)pyrazole; X = Cl, 2; X = Br, 3; X = I, 4; X = NO₂, 5) have been synthesized and characterized by ¹H NMR, ¹³C NMR, HRMS, elemental analysis. Complexes 2–5 have been further confirmed by X-ray diffraction. Their UV–Vis and emission spectroscopies, electrochemical measurements and acid–base properties are described. The results presented here reveal that the introduction of Cl, Br, I and NO₂ groups to the coordinated bpp⁻ ligand makes the absorption and emission maxima of the parent complex 1 blue-shifted, the oxidation potential of the Ru^II/Ru^III couple increased and the pK_a value decreased obviously. In addition, significant quenching of the emission by these groups is also observed.     

Synthesis, structures, and magnetic properties of binuclear carboxylate complexes with NiII and NiIII atoms

The reaction of NiCl₂·6H₂O with Me₃CCOOH and KOH taken in a molar ratio of 1:2:2 in water afforded the nonanuclear antiferromagnetic complex Py₂Ni₂(Me₃CCOOH)₂(OOCCMe₃)₂(μ-OOCCMe₃)₂(μ-OH₂), which apparently contains Ni^II and Ni^III atoms. The complex was isolated by extraction with CH₂Cl₂, benzene, or hexane. The reactions of this complex with pyridine bases (pyridine (Py), 3,4-lutidine (Lut), and nicorandil (Nic)) gave the adducts L₄Ni₂(OOCCMe₃)₂(μ-OOCCMe₃)₂(μ-OH) (L=Py, Lut, or Nic, respectively). According to magnetic measurements, intramolecular ferromagnetic exchange interactions in these adducts are complemented by intermolecular antiferromagnetic interactions. Pyrolysis of the pyridine adduct in air or under an inert atmosphere in xylene yielded the antiferromagnetic complex Py₂Ni₂(Me₃CCOOH)₂(OOCCMe₃)₂(μ-OOCCMe₃)₂(μ-OH₂), which contains Ni^II atoms. The structures of all the complexes synthesized were established by X-ray diffraction analysis. The electronic absorption spectra of these compounds are considered. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 725–738, April, 1998.     

Synthesis, characterizations and crystal structures of new organoantimony(V) complexes with various isomers of fluoromethylbenzoate ligands

Six new organoantimony(V) complexes containing various isomers of fluoromethylbenzoate ligands [RC₆H₃COO]₂SbPh₃ and [RC₆H₃COO]SbPh₄ [R = 3-F-4-(CH₃) (1, 4), 4-F-2-(CH₃) (2, 5), 5-F-2-(CH₃) (3, 6)] have been synthesized by the reactions of triphenylantimony(V) dichloride or tetraphenylantimony(V) bromide with various isomers of fluoromethylbenzoate ligands in 1:2 or 1:1 stoichiometries. All the complexes have been characterized by elemental analysis, IR and NMR [¹H, ¹³C and ¹⁹F] studies. The crystal structures of complexes 1, 3, 4, 5 and 6 have been determined by X-ray single crystal diffraction. The structure of complexes show that the five-coordinated antimony(V) atom adopts a distorted trigonal bipyramidal geometry. Furthermore, weak but significant intermolecular C–H···O, C–H···F hydrogen bonds, C–H···pi stacking lead to aggregation and assembly of these complexes into 1D and 2D supramolecular frameworks.     

Synthesis, X-ray structure and anti-corrosion activity of two silver(I) pyrazino complexes

Two new silver(I) pyrazine complexes [Ag₂(ampyz)(NO₃)₂]_n, 1 and {[Ag(2,3-pyzdic)](NO₃)}_n, 2 (where ampyz = aminopyrazine, and 2,3-pyzdic = 2,3-pyrazinedicarboxamide) were synthesized and structurally characterized by X-ray single crystal structure analysis. Complex 1 has a 2D sheet structure through both bridging μ_O,O′-(NO₃) groups and μ_N,N′-pyrazine moieties. A 3D structure with a characteristic (10,3)-d or 10³-utp net is formed through extensive hydrogen bonding. Complex 2 has a 1D chain structure through bridging μ_N,N′-pyrazine moieties. Strong hydrogen bonds further connect these chains to extend the dimensionality to a 3D network structure. The complexes were tested as corrosion inhibitors for mild steel in 0.1 M nitric acid medium using potentiodynamic polarization technique. Both complexes are of mixed type corrosion inhibitors with dominant anodic effect. The inhibition efficiencies are 68% and 50% for complexes 1 and 2, respectively. The inhibition mechanisms of both inhibitors are mainly due to adsorption of the inhibitor molecules on the surface of mild steel. All data were compared and fitted to the kinetic-thermodynamic model. The binding constants K are 3263 and 1147 for complexes 1 and 2, respectively.     

Synthesis and characterization of new platinum(II) phosphinate complexes

The syntheses of platinum(II) complexes of bis(dimethylphosphinylmethylene)amine and bis(aminomethyl)phosphinic acid were investigated. In the case of bis(dimethyl-phosphinylmethylene)amine the reaction with K₂[PtCl₄] yields the potassium amino-trichloroplatinate K[PtCl₃L] (L?=?bis(dimethylphosphinylmethylene)amine), which was characterized by multinuclear (¹H, ¹³C, ³¹P, and ¹⁹⁵Pt) NMR spectroscopy in solution. Bis(aminomethyl)phosphinic acid reacts with K₂[PtCl₄] under strictly controlled pH conditions to give colorless crystals of the cisplatin analog K[PtCl₂L′] (L′?=?bis(aminomethyl)phosphinate). This complex was characterized by multinuclear NMR spectroscopy in solution as well as by single-crystal X-ray diffraction in the solid state. The bis(aminomethyl)phosphinate coordinates to platinum via both amino functions, thus acting as a chelating ligand.     

Tuning haptotropic rearrangements of arene-chromium complexes: steric and electronic effects of phosphorus coligands

(Eta6-arene)tricarbonylchromium 2 was synthesised by [3+2+1] benzannulation of the Fischer carbene complex 1 and converted to the thermodynamically more favorable regioisomer 3 by haptotropic metal migration. Photo-induced ligand-exchange reactions in both regioisomers with triphenylphosphine, triphenylphosphite, trimethylphosphine, and trimethylphosphite afforded dicarbonyl(phosphine or phosphite)arene complexes 4-11. The regioisomers were separated by high-performance liquid chromatography (HPLC), and kinetic analyses of the thermo-induced haptotropic metal shift were performed with regioisomers 4, 6, 8, and 10. The kinetic parameters were compared with those obtained for the parent tricarbonyl complex 2 and were discussed in terms of the steric and electronic properties of the phosphorus ligands by applying a quantitative analysis of ligand effects (QALE). The molecular structures of regioisomeric PPh3 and P(OPh)3 complexes 4/5 and 6/7 as well as of P(OMe)3 complex 10 have been established by single-crystal X-ray analysis.     

Complexes of 1-boraadamantane and its derivatives with 1-azaadamantanes: Synthesis and molecular structure

The reactions of 1-boraadamantane and 2-methyl-, 2-ethyl-, 2,2-dimethyl-, and 3,5-dimethyl-substituted 1-boraadamantanes with their 1-azaadamantane analogs afforded a series of 1:1 adducts, which are stable to atmospheric air and moisture.^IH,¹³C, and³¹B NMR spectra as well as mass spectra of the compounds synthesized were investigated. Only the adduct of 2,2-dimethyl-1-boraadamantane with 2,2-dimethyl-1-azaadamantane readily dissociates into the initial components due to steric hindrances that prevent strong B→N coordination. The structure and geometric parameters of the 1-boraadamantane complex with 3,5-dimethyl 1-azaadamantane were established by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1818–1824, September, 1998.     

Synthesis and properties of 7,7-dichloro-3,4-benzobicyclo[4.1.0]heptane, its tricarbonylchromium complexes, and isomeric 7-chloro-3,4-benzobicyclo[4.1.0]heptanes

The reaction of Cr(CO)₆ with 7,7-dichloro-3,4-benzobicyclo[4.1.0]heptane gave the correspondingexo- andendo-chromium tricarbonyl complexes in a ratio of 4.5:1. The structures of the resulting compounds were established by NMR spectroscopy, mass spectrometry, and X-ray structural analysis. Reduction of dichlorobenzobicycloheptane and its chromium tricarbonyl complexes with LiAlH₄ affordedexo- andendo-7-chloro-3,4-benzobicyclo[4.1.0]heptanes in a 3.5:1 ratio. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 720–724, April, 1998.