Vibrational spectra of complexes of norbornadiene with transition metals

Russian Chemical Bulletin -     

Mass spectra of arylhydroxyoximes and their complexes with transition metals

The EI mass spectra of several arylhydroxyoximes and of their coordinated complexes with transition metals, Cu, Ni, Co and Fe have been studied using high resolution mass spectrometry, metastable ion measurements and the stable isotopes ¹⁵N, ⁶³Cu and ⁶⁵Cu labelling to elucidate the fragmentation pathways. It has been found that the spectra of all compounds 1–24 except Fe-complex 24 show molecular ions. The relative intensity of molecular ions of the complexes, which contained the same kind of metal and the arylhydroxyoximes with different substituents R , is closely related to the electronegativity of R. In all metal-complexes 9–22 , the main decomposition pathways involve the successive loss of O, NO and then H₂O or LH. In these spectra the fragment ions of non-metal- containing species resulting from the cleavage of the dioxime ligands can be discriminated.     

Norbornadiene complexes of transition metals

Conclusions Correlations were established between the stereochemistry of 2-(-carbinol)norbornadiene complexes of rhodium and their mass spectra.This study is also communication 30 from the series Mass Spectrometry of Transition Metal- Complexes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2701–2703, December, 1982.     

Cobalt-thioalkylazoimidazole complexes: Structures, spectra and redox properties

1-Alkyl-2-{(o-thioalkyl)phenylazo}imidazole (SRaaiNR^/, 1) reacts with Co(ClO₄)₂·6H₂O to form [Co(SRaaiNR^/)₂](ClO₄)₂ (2). The single crystal X-ray structure of one of the complexes of 2 shows a tridentate chelation N(imidazole), N(azo), S(thioether) system. In the structure one of ClO₄⁻ anions shows disorder and forms an (imidazole)C–H···O(ClO₃) interaction leading to a 1-D chain. Co(OAc)₂.4H₂O and SRaaiNR^/ react in the presence of NH₄SCN (1:1:2 mole ratio) in methanol and the complex [Co(SRaaiNR^/)₂(SCN)₂] (3) has been separated. The single crystal X-ray structure determination has established the structure of the complexes in which the ligand SRaaiNR^/ acts in a bidentate N(imidazole), N(azo) chelation mode. A cyclic voltammogram shows a Co(III)/Co(II) oxidative response at 0.6–0.8 V and azo reductions. DFT computation using optimized geometry support the electronic spectral and redox properties of the complexes.     

Structures,raman, infrared and electronic absorption spectra of pyridinium trihalides

Vibrational and electronic absorption spectra of PyHI₃, PyHIBr₂, PyHICl₂, PyHBr₃ and PyHBrCl₂ are presented and explained in terms of the vibrations and electronic transitions, respectively, of the pyridinium and trihalide ions. Two compounds, PyHI₃ and PyHBr₃, show charge transfer bands in the absorption spectra of the solids, and the vibrational spectrum of the PyH⁺ ion in solid PyHBr₃ differs from the normal PyH⁺ spectrum. PyHBr₃ as well as PyHI₃ contains asymmetric trihalide ions in the solid state, as can be concluded from the Raman and infrared spectra.     

Thermodecomposition ofo-benzoquinone complexes of transition metals

Thermodecomposition of 3,5- and 3,6-di-tert-butyl-o-benzoquinone complexes of Cu, Fe, Co, Cr, Mo, and W has been investigated in the solid phase by the thermogravimetric method. The relative stability of a series of complexes has been determined from the temperatures at which their decomposition begins. Detachment of a neutral electron-donor ligand takes place in the first stage. Detachment of ano-quinone ligand and decomposition of theo-benzoquinone formed occur in the next stage. Thermodecomposition of Fe, Co, Cr, Mo, and W complexes gives oxides or carbides, while copper complexes decompose to pure metal.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 327–329, February, 1994.     

Dihydrogen complexes of the transition metals

Summary The binding and activation of dihydrogen by simple transition metal complexes is of fundamental importance in processes as diverse as the homogeneous or heterogeneous hydrogenation of unsaturated organic molecules⁽¹⁾ and understanding how metalloenzymes such as nitrogenase⁽²⁾ and the hydrogenases⁽³⁾ work at the atomic level.Simple consideration of the oxidative-addition of dihydrogen to a coordinatively-unsaturated complex {or its reverse (reductive-elimination)} reveals that the reactions are compelled to proceed via a dihydrogen complex as shown in Equation (1). However until recently it was considered that the dihydrogen complex had only a fleeting existence. Although there had been some reports in the literature such as that by Ashworth and Singleton⁽⁴⁾ that the formally Ru^IV trihydride, [RuH₃(PMe₂Ph₂]⁺ was better formulated as the Ru¹¹ species [RuH(H₂)(PMe₂Ph)₂]⁺, these could not be substantiated. In 1984, though, Kubas showed that the apparently innocuous complex [WH₂(CO)₃(PPr ₃ ⁱ )₂] contained the side-on bonded dihydrogen molecule, established unambiguously by x-ray, and neutron crystallography and spectroscopy⁽⁵⁾. In this highlight the current status of dihydrogen complexes, their structure, identification and in particular their reactivity will be discussed.     

稀土谷胱甘肽配合物红外和Raman光谱研究

谷胱片肽是广泛存在于体内的重要三肽, 在体内主要以还原型(GSH)存在. GSH不但是清除体内过氧化物的还原剂, 而且与某些金属的配合物具有酶活性. 随着稀土的广泛应用, 其生物效应已引起关注. 了解稀土与GSH的配合物结构和性质, 将有利于了解稀土在体内的代谢和作用. 本文合成了十五种稀土与GSH的固体配合物,用IR和Raman光谱研究了配体在配合物中的变化及与稀土的配合位置.     

Structures and conformational behavior of phosphorothioites and their complexes with transition metals obtained from X-ray diffraction analysis

The data on the structures, conformational behavior, and coordination properties of phosphorothioites are summarized. Their complexes with transition metals are characterized by different modes of coordination depending on the nature of the metal atom, the substituents at the sulfur atoms, reaction conditions, and conditions of single-crystal growth. The principal differences in properties of phosphorothioites and their analogs containing the P—O and P—N bonds are analyzed.