Synthesis and atructure of [meso-triarylcorrolato]silver(III)

An efficient meso-triarylcorrole synthesis is detailed, and the formation and spectroscopic properties of their diamagnetic square-planar d(8) Ag(III) complexes are described. The spectroscopic properties of the [corrolato]Ag(III) complexes are contrasted with those of the corresponding [porphyrinato]Ag(II) complexes. The oxidation state of the central metal in the corrolato complexes was inferred from their diamagnetic NMR spectra, from X-ray photoelectron spectroscopy measurements, and by single-crystal X-ray diffractometry of the [meso-tetra-p-tolylcorrolato]silver(III) complex TTCAg(III), as its toluene solvate (crystal data for C(40)H(29)N(4)Ag.C(7)H(8): monoclinic space group C2/c with a = 21.4679(19) A, b = 20.7606(19) A, c = 16.0122(11) A, beta = 93.700(4) degrees, V = 7121.5(10) A(3), Z = 8, R = 0.0453, and R(w) = 0.1131). The conformation of the corrolato ligand in the complex is slightly saddled. The Ag(III) complexes are without precedent in the coordination chemistry of corroles. The Ag(III) complexes underline the ability of meso-triarylcorroles to stabilize higher oxidation states as compared to the corresponding meso-tetraarylporphyrinato complexes.     

Spatial structure and NMR spectra of strained [2.2.2]cyclophanes

The chemical shifts and coupling constants in the NMR spectra of the title compounds are influenced by their strain and the proximity of the aromatic rings. These parameters are studied by density functional theory (DFT) calculations for 1–4 and measured for 3 and 4. We find that, in spite of the strain, the calculations reproduce the experimental values satisfactorily. This finding is of special importance for novel hypothetical molecules like hexahydrosuperphane 5 for their future identification and in searches of hydrocarbons exhibiting unusual NMR parameters. Our results demonstrate the influence of strain on the parameters studied. Most proton and carbon chemical shifts for the molecules under study having nonplanar aromatic rings differ considerably from the corresponding values for the relatively unstrained trimethylbenzenes and ethylbenzene. In addition, the calculated values of the coupling constants through three bonds in most cases do not follow Karplus relation. Copyright © 2009 John Wiley & Sons, Ltd.     

X-ray photoelectron spectra of Rh(III) trifluoroacetate

A study was made of the x-ray photoelectron spectra of Rh(I) and Rh(III) trifluoroacetate complexes. It was shown by using the Cls bond energies of the carboxylate carbon atom as a basis that bridging and monodentate coordination of the trifluoroacetate group could be distinguished with high resolution.Institute of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1549–1551, July, 1992.     

X-ray structure analysis of poly[di-(3,4-dimethylphenoxy)phosphazene]

The crystal structure of oriented poly[di-(3,4-dimethylphenoxy) phosphazene] (PDMP) was determined by x-ray diffraction. Unit-cell parameters were found to be a = 15.85, b = 19.43, and c = 9.85 Å. The unit cell is metrically orthorhombic with monoclinic space group P2₁. There were 48 refinable diffraction spots in the observed reciprocal lattice region, of which 28 were observed and 20 were unobserved. A refined model yielded the following residuals: R^(obs) = 0.162 and 0.138. It was shown that a two-chain unit cell with a [T₃C]₂ (trans, trans, trans, cis, trans, trans, trans, cis) backbone conformation was the correct structure. The dimethylphenoxy side groups were arranged in nearly parallel planes, slightly off-normal to the fiber c axis. The polymer chains are extremely tightly packed and contain close but reasonable steric contacts.     

Computational study of [10]annulene NMR spectra

[reaction: see text] High-level theoretical methods are applied to calculate the 13C NMR chemical shifts of three isomers of [10]annulene. Comparison with experiment clearly shows that the carrier of NMR signals of the so-called B form is the "twist" isomer. The results of this study strongly support predictions of relative energies of mono-trans [10]annulene isomers at the CCSD(T) level, which in turn are in qualitative disagreement with DFT and MP2 calculations.     

Characterization and X-ray crystal structure of butanoylsalophencobalt(III)

The synthesis and characterization of the pentacoordinated butanoylsalophencobalt(III) compound, including X-ray analysis, are described. The chemical shift in the ¹³C-n.m.r. of the carbonyl carbon was determined by means of an HMBC experiment. Collision induced dissociation (CID) and high resolution mass spectrometry were used to establish the fragmentation pattern of the CoC₂₄H₂₁N₂O₃ compound. X-ray diffraction analysis shows the presence of two conformations for the acylsalophen ligand system in the same monocrystal, as well as two different OH–C hydrogen bonds with unusual interactions.     

13C NMR spectra of benzo[b]thiophene and 1-(X-benzo[b]thienyl)ethyl acetate derivatives

Carbon-13 chemical shift assignments are reported for benzo[b]thiophene and 1-(X-benzo[b]thienyl)ethyl acetate derivatives, where X=? CH(OAc)CH₃ substituted at positions 2-7. Substituent chemical shift (SCS) effects for the ethyl acetate group are additive at all positions. A substantial upfield shift was observed at C-3, arising from the peri interaction of H-3 and the 4-ethyl acetate substituent. Carbon-13 relaxation times (T₁) and nuclear Overhauser enhancements (η) have been measured for benzo[b]thiophene and its derivatives, and the contributions of dipolar, T^DD₁, and spin rotation, T^SR₁, relaxation have been determined. Intramolecular dipole–dipole interactions are found to provide by far the most important spin-lattice relaxation mechanism whenever protons are bound directly to the carbons under investigation. Nonprotonated ring carbons are relaxed by both DD and SR mechanisms. Anisotropic motion has an easily observable effect on the DD contribution to T₁, and can form the basis for spectral assignments, as in 1-phenylethyl acetate. Long-range ¹³C? ¹H coupling constants were observed both between ring carbons and between ring carbons with ring side-chain hydrogens. These results have been used for the structure determination of the title compounds.     

Diphenylantimony(III) acetate: spectra and crystal structure

Infrared data suggest that diphenylantimony acetate has a polymeric structure with bridging acetate groups which is partially broken down in carbon tetrachloride solution and completely destroyed in chloroform. The solid state structure has been determined by X-ray crystallography. The compound is triclinic, space group P$\text{1}$, with a 10.61(1), b 13.36(1), c 11.07(1) Å, α 106.9(1), β 116.7(1), γ 93.7(1)° and Z  4. The two independent antimony atoms are linked into polymeric chains by bridging acetate groups and are in pseudo trigonal bipyramidal coordination. The two phenyl groups (mean SbC, 2.155 Å) and the antimony lone pair occupy the equatorial positions while one axial position is occupied by an oxygen of the bonded acetate group (SbO, 2.137 Å).The bridge bonds occupy the second axial position leading to distances of 2.592 and 2.513 Å to Sb(1) and Sb(2).     

Synthesis and X-ray crystal structure of [2-(phosphinomethyl)ferrocenyl]diphenylphosphine

[2-(Phosphinomethyl)ferrocenyl]diphenylphosphine 2, is an air stable primary phosphine bearing a 1,2-disubstituted ferrocene framework, which has been prepared by reduction of the corresponding phosphonate. Confirmation of its structure has been obtained by X-ray single-crystals diffraction analysis. Despite its high stability toward oxidation, phosphine 2 still displays a normal coordinative behaviour toward [(p-cymene)RuCl₂]₂. The expected (p-cymene)RuCl₂(phosphine) complex is formed by coordination of the primary phosphine function, while the conceivably competitive complexation of the PPh₂ group was not observed.     

Synthesis, X-ray crystal structure and fluorescent spectra of novel pyrazolo[1,5-a]pyrazin-4(5H)-one derivatives

A series of fluorescent compounds, containing pyrazolo[1,5-a]pyrazin-4(5H)-one moiety, were designed and synthesized from ethyl 1-(2-oxo-2-phenylethyl)-3-phenyl-1H-pyrazole-5-carboxylates. The structures of the compounds have been confirmed by IR, (1)H NMR, HRMS and X-ray crystal diffraction. The optical properties of the compounds were investigated by UV-vis absorption and fluorescence spectroscopy. The effect of pH on the UV-vis absorption of compound 2a in methanol-H(2)O solutions was studied and interpreted by theory calculation. The pK(a) value of compound 2a was determined by the absorption spectra.     

Heteropolymetallic copper(II)-gold(III) dithiocarbamate [2]catenanes via magic ring synthesis

A rare class of mixed-metal [2]catenane has been assembled via magic ring synthesis of dinuclear copper(II) and gold(III) dithiocarbamate macrocycles.     

13C NMR spectra of tricyclo[4.2.1.02,5]nonanes and tetracyclo[5.4.1.02,6.08,11]dodecanes

The ¹³C NMR spectra of tricyclo[4.2.1.0^2,5]nonanes and tetracyclo[5.4.1.0^2,6.0^8,11]dodecanes and their dimethyl derivatives were measured to demonstrate the four-membered ring annelation effects on the bicyclo[2.2.1]heptane skeleton, and the steric δ-syn effects of the methyl groups attached to the four-membered ring on the bridge carbons in these systems.     

Organothallium compounds XII NMR spectra of some polyfluorophenylthallium (III) compounds

The PMR and ¹⁹F NMR spectra of the complexes R₂TlBr (R = C₆F₅, $\text{o}$-HC₆F₄, $\text{m}$-HC₆F₄, 3,5-H₂C₆F₃, or 3,6-H₂C₆F₃ and R₃Tl(diox) (R = C₆F₅, $\text{m}$-HC₆F₄, or 3,5-H₂C₆F₃; diox = 1,4-dioxan) have been recorded. Proton and fluorine chemical shifts, thallium-proton, thallium-fluorine, fluorine-fluorine, and fluorine-proton coupling constants, and thallium substituent chemical shifts are given and discussed     

NMR spectra and structure of 4,7-dimethylpyridazino[4,5-c]furoxane N,N′-dioxide

Conclusions NMR spectroscopy was used to confirm the structure of 4,7-dimethylpyridazino[4,5]furoxane N,N-dioxide obtained by the oxidation of diacetylfuroxane dioxide by nitrogen tetroxide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2848–2850, December, 1988.     

[4+2]-Cyclodimer of sabinone: formation,crystal structure,and NMR spectra

Oxidation of (+)-sabinol, (1S,3R,5S)-1-isopropyl-4-methylidenebicyclo[3.1.0]hexan-3-ol, by active MnO₂ afforded not the expected sabinone but only its [4+2]-cyclodimer. The molecular structure of the latter was established by X-ray diffraction analysis. The ¹H and ¹³C NMR spectra of this cyclodimer were interpreted using 2D NMR spectroscopy.     

Synthesis,spectra and X-ray crystal structure of a new type of macrocyclic hexanuclear iron(III) cluster

A macrocyclic iron(III) 18-azametallacrown-6 compound, [Fe₆(5-Brashz)₆(H₂O)₆]?·?20H₂O(5-Brashz?=?N-acetyl-(5-bromosalicylhydrazide)), where the pentadentate ligands bridge the metal ions, was synthesized and characterized. Due to the meridional coordination of the ligand to the metal ion, the ligand is not only bridging the ring metal ions using a hydrazide N–N group, but also enforcing the stereochemistry of the metal ions as a propeller shape with alternating Λ/Δ configuration. The disc-shaped hexanuclear cluster is about 14.5?Å in diameter, 16.8?Å in thickness and has a vacant cavity in the center of the cluster.     

X-ray K-absorption spectra of some aminoacid and carbonato complexes of copper(II)

Summary X-ray (K-) absorption edge spectrometric (XAES) investigations of some copper(II) chelates involving amino acids and a carbonato complex have been carried out employing a curved crystal spectrograph. Experimental edgewidths have been used to bear on the number of nearest neighbours around the central metal atom in the complexes in the solid state. Comparisons in respect of the nature of the metal-ligand bond have been made between inferences drawn on the basis of XAES, i.r. and optical spectral data. Average radii of the coordination sphere in the amino acid chelates have been reported using extended fine structure energy separations (Levy's method). In the carbonato complex, the possibility of determining different metal-donor distances within the coordination sphere has been suggested for the first time.